F-35 internal fuel, range

Unread postPosted: 12 Oct 2017, 16:02
by mixelflick
As I've become more familiar with it, the F-35 is starting to look like a real winner. Beyond the stealth, sensor fusion and maneuverability though, I'm fascinated with the gas.

So I understand it's 18,000lbs, which is 11,000lbs more than an F-16 and still quite a bit more than the Eagle (13,850), and she has two engines. SU-35 has almost 21,000 but again 2 engines..

So my question is: How they heck did LM get 18,000lbs of gas into such a small airframe? Is every nook and crannie not taken up by sensors packed w/ fuel?

Re: F-35 internal fuel, range

Unread postPosted: 12 Oct 2017, 16:19
by playloud
That's why the F-35 is a little pudgy.

Re: F-35 internal fuel, range

Unread postPosted: 12 Oct 2017, 16:21
by steve2267
playloud wrote:That's why the F-35 is a little pudgy.


That and internal weapons bays for 2K bombs...

Re: F-35 internal fuel, range

Unread postPosted: 12 Oct 2017, 16:23
by steve2267
mixelflick wrote:So my question is: How they heck did LM get 18,000lbs of gas into such a small airframe? Is every nook and crannie not taken up by sensors packed w/ fuel?


More or less...

Joint strike fighter fuel tank layout BAE.gif

Re: F-35 internal fuel, range

Unread postPosted: 12 Oct 2017, 17:13
by sprstdlyscottsmn
mixelflick wrote:So I understand it's 18,000lbs, which is 11,000lbs more than an F-16 and still quite a bit more than the Eagle (13,850), and she has two engines. SU-35 has almost 21,000 but again 2 engines.


can we please drop the "one engine vs two" nonsense?

Fuel flow is TSFC multiplied by Thrust. When in a cruise condition thrust is equal to drag. The factors that will impact range the most are L/D in cruise, fuel fraction, and TSCF.

What makes the F-16 so much more fuel efficient (nm per lb of fuel) than the F-15 is not having one engine, it's a smaller and lower drag airframe. That smaller airframe is due to having one engine, as the smallest plane you could wrap around two of those engines would be an F-15.

Su-27 is a big plane so it has two big engines.

The F-22 is a big plane so it has two big engines.

The F-35 is sized such that two F414s would equal the thrust, but would change the outer mold to be wider at the tail and narrower (top to bottom). A single engine was required by the Marines IIRC (or was it the AF, I can't recall at the moment).

The F-35 will never have the nm/lb that the F-16 has because it is BIGGER! Even with a similar L/D it needs so much more L that it gets that much more D as well. That much more D means more fuel flow. Now, it has so much fuel that it can double the fuel flow of an F-16 and still fly 32% further, and a similar L/D means the F-16 is carrying next to nothing while the F-35 can be carrying full fuel and 5k of weapons without changing L/Dmax (really takes configuration changes to adjust that). In fact, an F-35A with full fuel and 5k internal weapons weighs in at roughly 52,500lb. An F-16 with full fuel and nothing else is roughly 27,000lb. Meaning if they have the SAME L/D (and TSFC) when clean the F-16 will have fuel flows 51% that of the F-35, but it only carries 38% of the fuel, so it only gets 74% of the flight time (range depends on speed at which the L/D being discussed is hit).

The F-35 may have some performance issues that are less than stellar when compared to clean aircraft, but Range isn't one of them.

Re: F-35 internal fuel, range

Unread postPosted: 12 Oct 2017, 17:32
by mixelflick
OK well, I didn't know that. Thought 2 engines means it'd burn more fuel..

In any case, it really looks like the F-35 has some great legs. You always hear about how much gas Flankers carry/great range but you never hear about how much drag there is from lugging a meaningful weapons load around. Their AAM's look to be real draggy, hung off of a draggy airframe.

The F-35 sure is impressive...

Re: F-35 internal fuel, range

Unread postPosted: 12 Oct 2017, 17:48
by zhangmdev
I think that has something to do with F-35 uses fuel as hydraulic fluid and coolant for environment control. A first in fighter jets?

Re: F-35 internal fuel, range

Unread postPosted: 12 Oct 2017, 17:52
by steve2267
zhangmdev wrote:I think that has something to do with F-35 uses fuel as hydraulic fluid and coolant for environment control. A first in fighter jets?


Not sure about hydraulic fluid. All the flight controls use self-contained electrohydraulic actuators -- that is, they are sealed, and have their own hydraulic fluid / own pump etc. It was considered a technical risk at the beginning of the program, but appears to have worked very well. I am unsure if there is even a central hydraulic system for anything, and if so, if it uses fuel for the working fluid. I kind of doubt it... if you burned ALL your fuel, you would no longer have hydraulics. But I may be wrong.

I do believe fuel is used for cooling, though.

Re: F-35 internal fuel, range

Unread postPosted: 12 Oct 2017, 18:17
by neptune
steve2267 wrote:... I kind of doubt it... if you burned ALL your fuel, you would no longer have hydraulics. But I may be wrong.


....if you burn all the fuel, you don't need hydraulics.......OTOH you will arrive at the crash site, first!

....maybe you will alarm when the fuel quantity depletes to the minimum fueldraulic limit???
:)

Re: F-35 internal fuel, range

Unread postPosted: 12 Oct 2017, 18:35
by vanshilar
mixelflick wrote:OK well, I didn't know that. Thought 2 engines means it'd burn more fuel..


Well, it sort of does, but not directly because of the number of engines. Two engines tend to mean a bigger aircraft, which means more weight to move around and more drag, thus more fuel consumed. Or more accurately, a bigger aircraft tends to mean two engines, and a bigger aircraft tends to men more fuel consumed.

The SR-71 also used its fuel as a heat sink, which helped keep the skin relatively cool at Mach 3. "Relatively cool" meaning relative to the amount of heat at Mach 3 speeds.

Re: F-35 internal fuel, range

Unread postPosted: 12 Oct 2017, 18:39
by sprstdlyscottsmn
mixelflick wrote:OK well, I didn't know that. Thought 2 engines means it'd burn more fuel..


I apologize if the post sounded angry. I hate the loss of nonverbal communication in text. I only wanted to pass along the knowledge.

Re: F-35 internal fuel, range

Unread postPosted: 12 Oct 2017, 18:40
by zhangmdev
I searched fueldraulics. Seems it is used only on STOVL version, swiveling the three-bearing nozzle. So it has nothing to do the internal fuel/range. EHA does save a lot of piping.

Re: F-35 internal fuel, range

Unread postPosted: 12 Oct 2017, 18:47
by steve2267
zhangmdev wrote:I searched fueldraulics. Seems it is used only on STOVL version, swiveling the three-bearing nozzle.

Makes sense to use fuel as the working fluid for the swiveling nozzle.

zhangmdev wrote:So it has nothing to do the internal fuel/range. EHA does save a lot of piping.


In addition to saving weight (e.g. the piping you note), it should increase damage tolerance -- if a hit takes out an EHA survo, it is not going to rupture a hydraulic line resulting in loss of an entire hydraulic system. Also, less risk of fire as there is not an entire hydraulic system at risk of burning.

Re: F-35 internal fuel, range

Unread postPosted: 12 Oct 2017, 21:11
by spazsinbad
Thanks 'zhangmdev' and also the fuel storage diagram is no longer correct; 'quicksilver' says fuel is not stored in the tails.

Re: F-35 internal fuel, range

Unread postPosted: 12 Oct 2017, 23:35
by Gums
Salute!

Not so sure about your "analysis", Spurts.

1) I cannot find a F-16 GTOW you mention that only has internal fuel.

2) The two engine discussion is familiar to this old fart. It turns out that you can only pull the throttles back so far and you still have "x" pounds per hour, total. So in our over-powered A-37 we would have about 1500 - 1600 PPH total to maintain a good loiter AoA/speed. If we shut one down and pushed up the single engine we saw about 1300 PPH or so. The motor was running at a better point on the "curve" at a higher rpm.

The Hornet guys I first met said their fuel flow was about like an Eagle!! I discount the higher drag from more skin friction, but you could convince me.

3) I have a problem with asserting F-35 weight requiring lots more lift and associated induced drag. I'll bet that the sucker will come close to the 7 pounds per mile I saw in the Sluf and Viper, and that was total gas from climb to cruise and descent at home. e.g. RTB from 300 miles away using 2100 pounds plus reserve once there. worked every time.

Gums sends...

Re: F-35 internal fuel, range

Unread postPosted: 13 Oct 2017, 00:17
by spazsinbad
'Gums' IIRC the A4G 'rule of thumb' for quick mental gymnastics was 6 pounds per NM range at low altitude at 360 kannots.

Re: F-35 internal fuel, range

Unread postPosted: 13 Oct 2017, 00:36
by count_to_10
neptune wrote:
steve2267 wrote:... I kind of doubt it... if you burned ALL your fuel, you would no longer have hydraulics. But I may be wrong.


....if you burn all the fuel, you don't need hydraulics.......OTOH you will arrive at the crash site, first!

....maybe you will alarm when the fuel quantity depletes to the minimum fueldraulic limit???
:)

Alternately, if you spring a hydraulic leak, you would have the whole fuel tank as a reserve reservoir while you tried to get back to base. All the fuel in the world won't do you much good if you lose your controls.

Re: F-35 internal fuel, range

Unread postPosted: 13 Oct 2017, 00:40
by vanshilar
count_to_10 wrote:Alternately, if you spring a hydraulic leak, you would have the whole fuel tank as a reserve reservoir while you tried to get back to base. All the fuel in the world won't do you much good if you lose your controls.


Heh I guess it might also be nice for emergencies. If you start running low on fuel because of a leak at least they could refuel you on the way. If you start running low on hydraulic fluid I'm not sure what they can do.

Re: F-35 internal fuel, range

Unread postPosted: 13 Oct 2017, 03:23
by spazsinbad
Aaaah 'hydraulics'.... viewtopic.php?f=60&t=19215&p=351271&hilit=hydraulics#p351271

Damage control & testing was undergone years ago where proof obtained how the aircraft is able to fly with various damage bits & pieces. One claim is that it can fly with one tail IIRC - I'll look that up as well "...example, the F-35 can fly with one horizontal tail and one rudder missing..." http://www.aviationpros.com/article/109 ... ke-fighter

More: viewtopic.php?f=58&t=24027&p=307076&hilit=aviationpros#p307076

Good 'LIVE FIRE TEST' info: viewtopic.php?f=54&t=14199&p=221179&hilit=live+fire+test+bahdayton#p221179
&
viewtopic.php?f=22&t=16020&p=204074&hilit=live+fire+test+bahdayton#p204074

Re: F-35 internal fuel, range

Unread postPosted: 13 Oct 2017, 04:08
by sprstdlyscottsmn
Gums wrote:Salute!

Not so sure about your "analysis", Spurts.

1) I cannot find a F-16 GTOW you mention that only has internal fuel.

2) The two engine discussion is familiar to this old fart. It turns out that you can only pull the throttles back so far and you still have "x" pounds per hour, total. So in our over-powered A-37 we would have about 1500 - 1600 PPH total to maintain a good loiter AoA/speed. If we shut one down and pushed up the single engine we saw about 1300 PPH or so. The motor was running at a better point on the "curve" at a higher rpm.

The Hornet guys I first met said their fuel flow was about like an Eagle!! I discount the higher drag from more skin friction, but you could convince me.

3) I have a problem with asserting F-35 weight requiring lots more lift and associated induced drag. I'll bet that the sucker will come close to the 7 pounds per mile I saw in the Sluf and Viper, and that was total gas from climb to cruise and descent at home. e.g. RTB from 300 miles away using 2100 pounds plus reserve once there. worked every time.

Gums sends...

Salute!

My "analysis" was only to mathematically show the things that actually effect fuel burn. I will happily talk about each of your points and how they apply.

1) The HAF Blk 50/52+ -1 lists an empty weight of "about" 20,000lbs with oil, oxygen, unusable fuel, pilot, and tip missile rails with an internal usable fuel load of 7,162lb JP-8 (GE enigne, p.B1-6) giving ~27,000lb.

2)Turbine engines tend to run more efficiently the closer to a design throttle setting. Lower throttle settings will have a higher TSFC (more fuel burn). This is what you were seeing. Speed was the same, so drag was the same (maybe even a little higher with an engine out creating ram drag, unless you just idled it) so thrust was the same, so the improved TSFC for operating the one engine closer to the design point led to reduced fuel burn. Out of curiosity, was that in the manual or was that just a tricked you guys picked up?

2.5) the F404 has a higher TSFC than the F100. The F100 was a marvel in how much thrust it could make and how little fuel it could drink.

3) My actual analysis of Stubbies performance shows a greater L/D than the F-16 when clean. Not so much that it actually has less drag (I think it was on the order of 10-20% more drag), enough that it does not have to "pay" for all the extra weight with drag. I was using terms "even with a similar L/D" and "if they have the same L/D and TSFC" to show that even with pessimistic assumptions the F-35 still handily outranges the F-16. Looking back through my statements though I did not call out that these were pessimistic values. Oops. 7lb/nm comes out to ~.14nm/lb. A quick glance at the HAF -1 shows optimum cruise values not being less than .2nm/lb when clean, so I would buy .14nm/lb with climb and ordnance, no problem. My last Stubby model shows .10nm/lb from startup to approach on a 590nm radius optimum profile strike with two one-ton GPS bombs, landing with nearly 7k remaining in the tanks (can't remember if it was Col. Simms or Dolby Hanche that gave the statements I based that on).

"If the pilot took off with full fuel 2 amraams and 2 2000lbs bombs flew 590nm and came back with a 10 min weapon deployment time they would land with around 7,000-8,000lbs still in the tank."

1,180nm total for 10,500-11,500 of fuel, 0.1124nm/lb to 0.1026nm/lb fuel, heavy out, light back

Like I said, range is not one of Stubbys problems.

Re: F-35 internal fuel, range

Unread postPosted: 13 Oct 2017, 05:36
by steve2267
Gums wrote:
3) I have a problem with asserting F-35 weight requiring lots more lift and associated induced drag. I'll bet that the sucker will come close to the 7 pounds per mile I saw in the Sluf and Viper, and that was total gas from climb to cruise and descent at home. e.g. RTB from 300 miles away using 2100 pounds plus reserve once there. worked every time.

Gums sends...


When a pair of F-35A's flew from Eglin AFB to Oshkosh, the AOPA story had this to say about fuel burn:

F-35 Lightning public debut shows the right stuff
by David Tulis 8 August 2015

For the quick two hour, ten minute jaunt from Florida to AirVenture, each fighter jet burned about 5,000 pounds of fuel at 270 knots. Niemi said typical approach speeds are 150 knots and strictly by a 13-degree angle of attack all the way to the ground. “It’s a real easy plane to fly and it has good powerful [air] brakes. At 100 knots it will sit down pretty good,” he said.

Source: https://www.aopa.org/news-and-media/all ... ight-stuff


The great circle calculator gives 815nm from Eglin AFB to Oshkosh, which serves as a decent 1st order swag on nautical miles flown. 5000lb for 815nm works out to 6.1 lb/nm, just a little under Gums' 7lb/mile swag. (Gums, I presume you meant nautical mile when you said "miles"?)

Re: F-35 internal fuel, range

Unread postPosted: 13 Oct 2017, 05:47
by h-bomb
Gums wrote:Salute!

2) The two engine discussion is familiar to this old fart. It turns out that you can only pull the throttles back so far and you still have "x" pounds per hour, total. So in our over-powered A-37 we would have about 1500 - 1600 PPH total to maintain a good loiter AoA/speed. If we shut one down and pushed up the single engine we saw about 1300 PPH or so. The motor was running at a better point on the "curve" at a higher rpm.

The Hornet guys I first met said their fuel flow was about like an Eagle!! I discount the higher drag from more skin friction, but you could convince me.

Gums sends...


The F404 was originally called the J101 ultra low bypass turbofan. It is part of the F101/F110/F118 family, uses almost the same core as the F110. I wish I could remember who called it a turbojet with a leak. But it is very low bypass 0.34:1, verse the F110's 0.76.

Re: F-35 internal fuel, range

Unread postPosted: 13 Oct 2017, 07:05
by hornetfinn
playloud wrote:That's why the F-35 is a little pudgy.


I prefer "curvy"... :P

Re: F-35 internal fuel, range

Unread postPosted: 13 Oct 2017, 07:17
by hornetfinn
mixelflick wrote:In any case, it really looks like the F-35 has some great legs. You always hear about how much gas Flankers carry/great range but you never hear about how much drag there is from lugging a meaningful weapons load around. Their AAM's look to be real draggy, hung off of a draggy airframe.

The F-35 sure is impressive...


It sure is... F-35A

1. Has similar dimensions to F-16
2. Has about 2.5 times the internal fuel of F-16 or 80% of internal fuel volume of Strike Eagle with CFTs
3. Can carry 5,000 lbs of weapons internally
4. Carries advanced targeting pod, insane amount of avionics systems and extensive EW capabilities internally
5. Can do Mach 1.6, 9G and 50 degree AoA maneuvers while carrying all of the above
6. Is the stealthiest fighter jet in existence according to everybody in the know

Re: F-35 internal fuel, range

Unread postPosted: 13 Oct 2017, 13:45
by steve2267
hornetfinn wrote:It sure is... F-35A

1. Has similar dimensions to F-16
2. Has about 2.5 times the internal fuel of F-16 or 80% of internal fuel volume of Strike Eagle with CFTs
3. Can carry 5,000 lbs of weapons internally
4. Carries advanced targeting pod, insane amount of avionics systems and extensive EW capabilities internally
5. Can do Mach 1.6, 9G and 50 degree AoA maneuvers while carrying all of the above
6. Is the stealthiest fighter jet in existence according to everybody in the know


Is it commonly accepted that the F-35A has a lower RCS than the F-22? Or are we discussing "total signature" to include visual + thermal? Regarding RCS, the last number I saw cited (or stated) for the F-22 was 0.0001 m^2, or the "size of a marble." Are you stating the F-35 comes in less than that number (or have read statements by "people in the know" stating or implying that to be the case)?

Re: F-35 internal fuel, range

Unread postPosted: 13 Oct 2017, 14:03
by hornetfinn
steve2267 wrote:
hornetfinn wrote:It sure is... F-35A

1. Has similar dimensions to F-16
2. Has about 2.5 times the internal fuel of F-16 or 80% of internal fuel volume of Strike Eagle with CFTs
3. Can carry 5,000 lbs of weapons internally
4. Carries advanced targeting pod, insane amount of avionics systems and extensive EW capabilities internally
5. Can do Mach 1.6, 9G and 50 degree AoA maneuvers while carrying all of the above
6. Is the stealthiest fighter jet in existence according to everybody in the know


Is it commonly accepted that the F-35A has a lower RCS than the F-22? Or are we discussing "total signature" to include visual + thermal? Regarding RCS, the last number I saw cited (or stated) for the F-22 was 0.0001 m^2, or the "size of a marble." Are you stating the F-35 comes in less than that number (or have read statements by "people in the know" stating or implying that to be the case)?


According to General Mike Hostage it is:

https://breakingdefense.com/2014/06/gen ... -starts/3/

The F-35’s cross section is much smaller than the F-22’s, but that does not mean, Hostage concedes, that the F-35 is necessarily superior to the F-22 when we go to war.


According to LM:
https://www.f35.com/about/capabilities/stealth
The stealth capabilities in the F-35 are unprecedented in military aviation.

Re: F-35 internal fuel, range

Unread postPosted: 13 Oct 2017, 14:18
by playloud
hornetfinn wrote:According to General Mike Hostage it is:

https://breakingdefense.com/2014/06/gen ... -starts/3/

The F-35’s cross section is much smaller than the F-22’s, but that does not mean, Hostage concedes, that the F-35 is necessarily superior to the F-22 when we go to war.


According to LM:
https://www.f35.com/about/capabilities/stealth
The stealth capabilities in the F-35 are unprecedented in military aviation.

General Bogdan also concurred...

http://www.airforcemag.com/MagazineArch ... roach.aspx
"I would say that General Hostage … is accurate in his statement about the simple stealthiness of the F-35 [with regard] to other airplanes," Bogdan said in the interview. The statement was accurate for radar cross section, as measured in decibels, and range of detectability, he said, and he scoffed at the notion that anyone can tell how stealthy an aircraft is just by looking at it.

Re: F-35 internal fuel, range

Unread postPosted: 13 Oct 2017, 15:34
by Gums
Salute!

THNX for the update, Spurts.

Gross weight? Spurts 1, Gums 0.5 I'm too old and forgot about all the weight increase as the Viper porked up over last 30 years, heh heh. Remember, I cut my teeth on the original "lightweight fighter" !!!!!

Single engine cruise? It was a standard procedure for the A-37 for at least first 6 or 7 years. We used it mostly to loiter, so I would cross my fingers and shut one down in the middle of the night over the Trail and wait for Covey or Blindbat to find a truck convoy. We hardly ever cruised to the tgt on one motor due to ordnance drag. I flew twice from Colorado to Louisiana with only two drop tanks - over 700 n.m. We had to switch motors after a half an hour or so to keep the lubrication where it was supposed to be.

Optimum engine rpm? Yep, Spurts. We're in the zone on that. Even at idle, the J85 was still using 300 - 400 pph.

I, too, saw the "leaky turbojet" comment back in 1974 or so. It was an interview in AvWeek, best I recall. I just think the Hornet was/is too draggy. Even with the pylons on the sluf, both it and the Viper were amazing descending at 300 kias and using only 500 pph. We would pull back to idle 100 miles out, 35,000 ft and put the flight path marker on the homebase TD box. We would soon get to 300 kias and maybe a bit higher.

Gums sends....

Re: F-35 internal fuel, range

Unread postPosted: 15 Oct 2017, 19:07
by 010137
Gums wrote:Salute!

Not so sure about your "analysis", Spurts.

1) I cannot find a F-16 GTOW you mention that only has internal fuel.

2) The two engine discussion is familiar to this old fart. It turns out that you can only pull the throttles back so far and you still have "x" pounds per hour, total. So in our over-powered A-37 we would have about 1500 - 1600 PPH total to maintain a good loiter AoA/speed. If we shut one down and pushed up the single engine we saw about 1300 PPH or so. The motor was running at a better point on the "curve" at a higher rpm.

The Hornet guys I first met said their fuel flow was about like an Eagle!! I discount the higher drag from more skin friction, but you could convince me.

3) I have a problem with asserting F-35 weight requiring lots more lift and associated induced drag. I'll bet that the sucker will come close to the 7 pounds per mile I saw in the Sluf and Viper, and that was total gas from climb to cruise and descent at home. e.g. RTB from 300 miles away using 2100 pounds plus reserve once there. worked every time.

Gums sends...


Fuel flow is measured in lbs/min in this aircraft. Normally 20's - mid 30k cruising .8-.92M you're burning between 85-100 lbs/min; generally figure 100 for planning but we will beat that a lot. FADEC seems to keep fuel flow pretty constant in a lot of different situations. Max endurance will generally stabilize around 85lbs/min 250-280kts. Unlike a lot of other a/c, you don't buy nearly as much during an idle descent as it seems to take a lot of fuel to keep this gigantic engine turning, around 50lbs/min.

For reference, two tanked F-18 max endurance with pylons you figure 4800 lbs/hour fuel burn. Goes up quickly with speed increase.

Re: F-35 internal fuel, range

Unread postPosted: 15 Oct 2017, 20:58
by count_to_10
010137 wrote:
Gums wrote:Salute!

Not so sure about your "analysis", Spurts.

1) I cannot find a F-16 GTOW you mention that only has internal fuel.

2) The two engine discussion is familiar to this old fart. It turns out that you can only pull the throttles back so far and you still have "x" pounds per hour, total. So in our over-powered A-37 we would have about 1500 - 1600 PPH total to maintain a good loiter AoA/speed. If we shut one down and pushed up the single engine we saw about 1300 PPH or so. The motor was running at a better point on the "curve" at a higher rpm.

The Hornet guys I first met said their fuel flow was about like an Eagle!! I discount the higher drag from more skin friction, but you could convince me.

3) I have a problem with asserting F-35 weight requiring lots more lift and associated induced drag. I'll bet that the sucker will come close to the 7 pounds per mile I saw in the Sluf and Viper, and that was total gas from climb to cruise and descent at home. e.g. RTB from 300 miles away using 2100 pounds plus reserve once there. worked every time.

Gums sends...


Fuel flow is measured in lbs/min in this aircraft. Normally 20's - mid 30k cruising .8-.92M you're burning between 85-100 lbs/min; generally figure 100 for planning but we will beat that a lot. FADEC seems to keep fuel flow pretty constant in a lot of different situations. Max endurance will generally stabilize around 85lbs/min 250-280kts. Unlike a lot of other a/c, you don't buy nearly as much during an idle descent as it seems to take a lot of fuel to keep this gigantic engine turning, around 50lbs/min.

For reference, two tanked F-18 max endurance with pylons you figure 4800 lbs/hour fuel burn. Goes up quickly with speed increase.

These are the considerations that got me wondering if it was possible to power the compressor by sending only a small fraction of the combuster air through the turbine, while the fuel burned in the rest of the air is varied to control thrust.

viewtopic.php?f=38&t=53008

Re: F-35 internal fuel, range

Unread postPosted: 15 Oct 2017, 21:05
by Gums
Salute!

@010 Need a better callsign, man.

With ppm versus pph, are we talking about the Stubby or the Bug?

Either one it's depressing. My trusty J-57 back in the 60's burned about 3,000 pph, or 50 ppm, I guess. That was a basic cruise or loiter, although I managed to get that down to 2,200 pph or so if I was smooth at best AoA.

In the Deuce, the fuel flow was for one motor, but in the VooDoo you could almost double it but normally about 5,000 pph. Later in life I wondered about shutting down a motor in the VooDoo, as we could maintain 1.15M at 49,000 ft with one in mil and the other at min burner. But A-37 was so overpowered it was an easy decision to shut one down.

Then I flew the Sluf and Viper. We cruised at 2,000 pph ( 33 ppm ? ) , 35K and 0.8M in the Sluf or 0.9M in the Viper or so when RTB with only pylons and missiles on 1 and 9. Maybe a centerline tank.

Re: F-35 internal fuel, range

Unread postPosted: 15 Oct 2017, 21:48
by 010137
Gums wrote:Salute!

@010 Need a better callsign, man.

With ppm versus pph, are we talking about the Stubby or the Bug?

Either one it's depressing. My trusty J-57 back in the 60's burned about 3,000 pph, or 50 ppm, I guess. That was a basic cruise or loiter, although I managed to get that down to 2,200 pph or so if I was smooth at best AoA.

In the Deuce, the fuel flow was for one motor, but in the VooDoo you could almost double it but normally about 5,000 pph. Later in life I wondered about shutting down a motor in the VooDoo, as we could maintain 1.15M at 49,000 ft with one in mil and the other at min burner. But A-37 was so overpowered it was an easy decision to shut one down.

Then I flew the Sluf and Viper. We cruised at 2,000 pph ( 33 ppm ? ) , 35K and 0.8M in the Sluf or 0.9M in the Viper or so when RTB with only pylons and missiles on 1 and 9. Maybe a centerline tank.


Ppm is for the f-35. Pph displayed for the hornet. You would be amazed at the ppm burned in blower... 90ppm at .85m (or 10.5 lbs/nm) is pretty awesome for a motor that produces 40k thrust, especially with how much internal gas we have.

Re: F-35 internal fuel, range

Unread postPosted: 16 Oct 2017, 07:12
by geforcerfx
010137 wrote:
Ppm is for the f-35. Pph displayed for the hornet. You would be amazed at the ppm burned in blower... 90ppm at .85m (or 10.5 lbs/nm) is pretty awesome for a motor that produces 40k thrust, especially with how much internal gas we have.


Is that with internal GBU's? what F-35 variant?

Re: F-35 internal fuel, range

Unread postPosted: 16 Oct 2017, 15:23
by 010137
geforcerfx wrote:
010137 wrote:
Ppm is for the f-35. Pph displayed for the hornet. You would be amazed at the ppm burned in blower... 90ppm at .85m (or 10.5 lbs/nm) is pretty awesome for a motor that produces 40k thrust, especially with how much internal gas we have.


Is that with internal GBU's? what F-35 variant?


Yes, w ord. B model, but they’re all about the same.

Re: F-35 internal fuel, range

Unread postPosted: 16 Oct 2017, 19:06
by geforcerfx
010137 wrote:
Yes, w ord. B model, but they’re all about the same.


Thanks for answering. The Air Force had a stat posted saying at 30k and .7 (or .75) they burn around 4000 PPH. Your burning around 5400pph going .85, would that small reduction in speed really reduce consumption that much?

Re: F-35 internal fuel, range

Unread postPosted: 16 Oct 2017, 22:28
by johnwill
No surprise. The drag at 0.85 is about 50% greater than at 0.70.

Re: F-35 internal fuel, range

Unread postPosted: 16 Oct 2017, 23:21
by geforcerfx
johnwill wrote:No surprise. The drag at 0.85 is about 50% greater than at 0.70.


transonic is that bad? I had read like 30%

Re: F-35 internal fuel, range

Unread postPosted: 16 Oct 2017, 23:36
by viper12
I think johnwill simply meant that drag is roughly proportional to the square of speed in this region, since (0.85/0.7)^2 = 1.47.

Re: F-35 internal fuel, range

Unread postPosted: 17 Oct 2017, 02:00
by sprstdlyscottsmn
geforcerfx wrote: The Air Force had a stat posted saying at 30k and .7 (or .75) they burn around 4000 PPH.


Specifically it was .75M, 32,000ft, 4,600pph (76.7ppm), with 2500lb tactical loadout internal.

Re: F-35 internal fuel, range

Unread postPosted: 17 Oct 2017, 02:24
by Dragon029
I think he's talking about this one:

Image

Mach 0.75, 40kft, no payload specified, 593 gal/hr (= 4032.4pph = 67.21ppm)

Re: F-35 internal fuel, range

Unread postPosted: 17 Oct 2017, 03:22
by viper12
5 gal/hr for the Predator ! :shock:

Even with the relatively small Cessna 172P, our instructors told us to use the conservative 10 gal/hr fuel consumption, and we didn't fly above 100 kt IAS !

Re: F-35 internal fuel, range

Unread postPosted: 17 Oct 2017, 04:44
by sprstdlyscottsmn
Dragon029 wrote:I think he's talking about this one:

Image

Mach 0.75, 40kft, no payload specified, 593 gal/hr (= 4032.4pph = 67.21ppm)

Ooh, more data, excellent.

Re: F-35 internal fuel, range

Unread postPosted: 17 Oct 2017, 04:51
by popcorn
Have therr been any credible reports discussing the F-35 range where it's explicitly stated it's got empty bays? I 've always assumed a full internal ordnance load.

Re: F-35 internal fuel, range

Unread postPosted: 17 Oct 2017, 05:16
by Dragon029
Not that I'm aware of; even on a slide describing a surveillance mission they have a payload of 2x AIM-120s and 2x GBU-12s:

Image

(Just note that this was from something like 2012, so I'm not sure how accurate those performance figures are - if they're based off the SAR performance estimates though then they'll be even higher).

Re: F-35 internal fuel, range

Unread postPosted: 17 Oct 2017, 05:36
by optimist
also the altitude is varying between 5-25k. We don't know time at any altitude or the speed, to give a the breakdown of the mission requirements that give the range.

Re: F-35 internal fuel, range

Unread postPosted: 17 Oct 2017, 06:05
by geforcerfx
yup that's it, thanks dragon couldn't find it in my "F-35" folder need to spend a night and organize that folder a bit. If advent technology engine turns out to be as amazing as they are hyping it then the F-35's will have a 50,000lb thrust engine (afterburner) that can cruise at .75 and only sip 3200lbs of fuel, freaking insane. That's a 1,000nmi combat radius upgrade right there, not to mention the insane increase to the already (very?) healthy subsonic acceleration.

Re: F-35 internal fuel, range

Unread postPosted: 17 Oct 2017, 06:10
by Dragon029

Re: F-35 internal fuel, range

Unread postPosted: 17 Jan 2018, 18:10
by mixelflick
sprstdlyscottsmn wrote:
mixelflick wrote:OK well, I didn't know that. Thought 2 engines means it'd burn more fuel..


I apologize if the post sounded angry. I hate the loss of nonverbal communication in text. I only wanted to pass along the knowledge.


Yeah it came off that way, LOL. But it's all good. I learned a great deal given your explanation and that's why we come here! I'm just a guy who loves planes. Was my dream to be a fighter pilot (but bad, bad stigmatisms). I wanted to fly the F-15 and still love that jet. When I found out a Viper had the same/better legs, I was shocked.

But the F-35 being what it is, it impresses me more every day. A jet capable of carrying 5,000lbs mixed air to air/ground load, ridiculous SA/sensors, mach 1.6 dash speed AND 9g capable carrying that load. And oh, Lockheed threw in an invisibility switch. To add to all this, it has great legs.

I think when it's all said and done she'll have an F-15 like reputation, she'll be that dominant.

Re: F-35 internal fuel, range

Unread postPosted: 17 Jan 2018, 18:42
by mixelflick
hornetfinn wrote:
mixelflick wrote:In any case, it really looks like the F-35 has some great legs. You always hear about how much gas Flankers carry/great range but you never hear about how much drag there is from lugging a meaningful weapons load around. Their AAM's look to be real draggy, hung off of a draggy airframe.

The F-35 sure is impressive...


It sure is... F-35A

1. Has similar dimensions to F-16
2. Has about 2.5 times the internal fuel of F-16 or 80% of internal fuel volume of Strike Eagle with CFTs
3. Can carry 5,000 lbs of weapons internally
4. Carries advanced targeting pod, insane amount of avionics systems and extensive EW capabilities internally
5. Can do Mach 1.6, 9G and 50 degree AoA maneuvers while carrying all of the above
6. Is the stealthiest fighter jet in existence according to everybody in the know


Someone really needs to make a graphic reflecting these points, asking - can your fighter do this?

I thought I saw one here, but can't recall where. In any case, this was a great summary. It really illustrates the magnitude of what Lockheed has accomplished. This ain't the F-111...

Re: F-35 internal fuel, range

Unread postPosted: 17 Jan 2018, 19:49
by Dragon029
While this thread is revived, could someone help me find the source article where it was stated that F-35s participating had twice the combat endurance of F-15Cs during training exercises?

IIRC they specifically talked about F-15s going out on vuls, coming back to refuel, going again and coming back again while F-35s stuck around the entire time, with reference to the F-35's being force multipliers / seeing things that the 4th gens didn't.

Re: F-35 internal fuel, range

Unread postPosted: 17 Jan 2018, 20:37
by sprstdlyscottsmn
that would be a nice one to add to the collection of quotes.

Re: F-35 internal fuel, range

Unread postPosted: 17 Jan 2018, 20:56
by steve2267
Pretty sure I already quoted it. Nope... I didn't. I know the quote of which you speak. I'll see if I can find it.

ETA: My google-fu is weak today. I recall the interview. I want to say the F-35 pilot was a Lt Col or Col, possibly from Hill AFB. I also want to say the article was around the time frame of the F-35 turkey shoot up there in Michigan last year or in 2016.

Maybe the F-16.net WayBack Machine will find it when Spaz reads this thread...

Re: F-35 internal fuel, range

Unread postPosted: 17 Jan 2018, 21:25
by operaaperta
Hi Dragon,

The quote you are looking for is near the end of this video

https://m.youtube.com/watch?feature=you ... TgDTC8_PM0

Re: F-35 internal fuel, range

Unread postPosted: 17 Jan 2018, 21:35
by spazsinbad
:devil: She's got legs & knows how to use 'em.... ZZ TOP... :doh:
Q: "How's the range of the aircraft from an operator perspective?"

CAP: [Lt. Col. Scott “Cap” Gunn USAF] "I think people that say it doesn't have the range are someone that probably looks at a single-engine aircraft and think so it's just an F-16. It aint an F-16.

I fly on a regular basis two training stories worth of training that I would do in an F-15C model with two external tanks on it. So I would go up go out and do one offensive push where we do basically one offensive strike into the area and out and hey I'm bingo I've got to go home on fuel with the F-15C.

In the F-35 I'll go out and do two of those without any problem and one of the things that we found out in the exercise up in Wisconsin, was after we were done firing our weapons after we were done getting everybody into and out of the combat area, if we wanted to go on to keep fighting at that point they would ask us to stick around because of all the sensors we could provide and the data link we could provide to help the 4th gen aircraft who still had missiles on board. We still had fuel and the sensors to be able to provide that information form.

So it's got legs, it's got really long legs." viewtopic.php?f=22&t=52482&p=355916&hilit=Gunn#p355916


Re: F-35 internal fuel, range

Unread postPosted: 18 Jan 2018, 05:44
by Dragon029
Cheers guys, I've added it to my archive:

https://www.reddit.com/r/Dragon029/wiki/kinematics

Re: F-35 internal fuel, range

Unread postPosted: 20 Jan 2018, 10:24
by element1loop
So is a glut of Alled tanking capacity emerging in a decade or so? Has this F-35 madness touched off yet another airpower calamity?

What a lemon. :wtf:

Re: F-35 internal fuel, range

Unread postPosted: 20 Jan 2018, 16:16
by mixelflick
Better range (much better) than an F-15C with wing tanks? Fantastic..

I bet it out-ranges most Flankers, given their draggy airframes. It carries a ton of gas, but if I'm not mistaken range is strongly correlated to lift/drag index.

Re: F-35 internal fuel, range

Unread postPosted: 20 Jan 2018, 20:05
by viper12
mixelflick wrote:It carries a ton of gas, but if I'm not mistaken range is strongly correlated to lift/drag index.


Range is correlated to this ratio, but it's only proportional in a cruise/climb ; it still appears in the equation for a constant altitude : https://en.wikipedia.org/wiki/Range_(aeronautics)#Jet_propulsion

Re: F-35 internal fuel, range

Unread postPosted: 21 Jan 2018, 02:41
by element1loop
Does anyone remember the link to the LM article detailing a 5.7 hour cross-country range/endurance flight test/ verification? (obviously requiring a landing with the 2,500 lb reserve intact)

Re: F-35 internal fuel, range

Unread postPosted: 21 Jan 2018, 03:08
by spazsinbad
I bin lookin' but interrupted search to post this - again - for this thread. First found by 'SWP' many moons ago now - in Oz:
"...Mr Burbage: We have 16 key performance parameters on this airplane. Half are logistics and sustainment-related, half are aeroperformance-related and one or two are in classified areas. We have an oversight body called the Joint Requirements Oversight Council, the JROC, that looks at those requirements every year and makes decisions on them—'Are we going to meet them, are we not going to meet them? If we are not going to meet them, what is the impact of that?' We have one this year which was the range of the Air Force airplane which had a specific set of ground rules associated with how that range is calculated which is not similar to either of the other two airplanes. The airplane flies a large part of its mission at a non-optimised altitude in the original calculation. The JROC agreed to change the ground rules to fly that airplane as the other two were flown and, when that happened, the airplane had excess margin to the range requirement. For any performance-related requirements, we artificially penalise the engine by five per cent fuel flow and two per cent thrust. Those margins are given back as we mature the design and get more and more solid on exactly what it is going to do. They are there for conservative estimation up front. We have not taken back any of those margins yet so, when those margins are taken back, the airplane will continue to be well in excess of its basic requirement. The airplane is meeting all of the other requirements today...." 20 March 2012 Australian Federal Parliament F-35 Inquiry viewtopic.php?f=58&t=18916&p=220218&hilit=cross+country+test#p220218

Bin Lookin' at the OLD LM Flight Test Updates - this example is NOT what is required but use it as 'reference' for lookin'.
"...18 December 2009: USMC Pilot Completes Longest Duration Flight
US Marine Corps pilot Maj. Joseph Bachmann completes the longest flight on an F-35 to date during the fifteenth flight of BF-2. The 3.7-hour mission, which includes aerial refueling, is in preparation for the ferry flight that will take the aircraft directly from Fort Worth, Texas, to Patuxent River, Maryland...." http://www.codeonemagazine.com/f35_arti ... item_id=11

:mrgreen: Here we go - here we go - here we go (it is bleedin' hot here upside down in these parts & no aircon...) :doh:
"...17 December 2013: Longest Flight Duration
Lockheed Martin test pilot Paul Hattendorf was at the controls of F-35A AF-7 for a 5.2-hour mission systems test flight from Edwards AFB, California. The flight, which also marked 500 hours for AF-7, was the longest test mission to date for the F-35 program. Coincidentally, Lockheed Martin test pilot David Nelson completed a 5.2-hour mission on the same day in F-35A AF-3...." [Did it ARF? Air ReFuel? Did it land back at Edwards AFB?] http://www.codeonemagazine.com/article.html?item_id=136

And AGAIN & AGAIN & AGAIN...
"...25 February 2014: Longest Flights To Date
Two F-35 pilots broke the single flight F-35 duration record during the first AMRAAM launch at White Sands Missile Range, New Mexico. Air Force Maj. Mark Massaro flying BF-18 and Air Force Maj. Andrew Rollins flying AF-6 completed the round trip from Edwards AFB to the range in 5.7 hours. The previous duration record was 5.1 hours...."
http://www.codeonemagazine.com/article.html?item_id=136

Re: F-35 internal fuel, range

Unread postPosted: 21 Jan 2018, 03:47
by element1loop
Maybe this helps, from memory it was in LM's flight testing summaries section ... about mid to late 2016, if I remember correctly.

Edit

Just saw your reply spaz, close, not quite it, there was a later 5.6 hr and a few months later, a 5.7 hr test. Definitely a few years later than 2013.

Re: F-35 internal fuel, range

Unread postPosted: 21 Jan 2018, 03:53
by alloycowboy
"Non optimized" meaning they were flying the F-35 at low altitude on deck where the fuel burn is high like it was a Eurofighter Typhoon or something. Instead of fly the F-35 at optimum altitude where the Prat and Whitney F-135 jet engine is the most efficient and relying on the Low Obeservable technology of the airframe to reduce radar return.

Re: F-35 internal fuel, range

Unread postPosted: 21 Jan 2018, 03:53
by spazsinbad
element1loop wrote:Maybe this helps, from memory it was in LM's flight testing summaries section ... about mid to late 2016, if I remember correctly.

No worries - LOOK BACK AT EDIT on previous page - My method is to post then edit post edit at same place - bad - I know.

Repeated here because who looks back? Who reads articles? Questions Questions Questions....
"...25 February 2014: Longest Flights To Date
Two F-35 pilots broke the single flight F-35 duration record during the first AMRAAM launch at White Sands Missile Range, New Mexico. Air Force Maj. Mark Massaro flying BF-18 and Air Force Maj. Andrew Rollins flying AF-6 completed the round trip from Edwards AFB to the range in 5.7 hours. The previous duration record was 5.1 hours...."
http://www.codeonemagazine.com/article.html?item_id=136

Re: F-35 internal fuel, range

Unread postPosted: 21 Jan 2018, 04:06
by element1loop
See my edit above spaz, cheers.

Re: F-35 internal fuel, range

Unread postPosted: 21 Jan 2018, 04:21
by element1loop
spazsinbad wrote:
element1loop wrote:Maybe this helps, from memory it was in LM's flight testing summaries section ... about mid to late 2016, if I remember correctly.

No worries - LOOK BACK AT EDIT on previous page - My method is to post then edit post edit at same place - bad - I know.

Repeated here because who looks back? Who reads articles? Questions Questions Questions....
"...25 February 2014: Longest Flights To Date
Two F-35 pilots broke the single flight F-35 duration record during the first AMRAAM launch at White Sands Missile Range, New Mexico. Air Force Maj. Mark Massaro flying BF-18 and Air Force Maj. Andrew Rollins flying AF-6 completed the round trip from Edwards AFB to the range in 5.7 hours. The previous duration record was 5.1 hours...."
http://www.codeonemagazine.com/article.html?item_id=136



Awesome work! Thank you. :salute:

Re: F-35 internal fuel, range

Unread postPosted: 21 Jan 2018, 04:31
by element1loop
However, there actually is a single aircraft flight test in about 2016 that made the 5.6 and 5.7 results. A formal test.

Re: F-35 internal fuel, range

Unread postPosted: 21 Jan 2018, 04:35
by spazsinbad
That F-35 test is probably in the F-35 SAR report for that year (on later) - do we assume it is unrefueled/ARFed? Report could be in bigwig text submission to US Congress about F-35 progress? Dec 2015 SAR is here [they are dated weird]:

https://fas.org/man/eprint/F35-sar-2016.pdf (0.6Mb) ["As of FY 2017 President's Budget" BUT DEC 2015 - ffsake I give up]

There are other reports such as - DOT&E Annual Reports - that was what I was thinking might contain such information....

Re: F-35 internal fuel, range

Unread postPosted: 21 Jan 2018, 04:49
by element1loop
spazsinbad wrote:That F-35 test is probably in the F-35 SAR report for that year (on later) - do we assume it is unrefueled/ARFed? Report could be in bigwig text submission to US Congress about F-35 progress? Dec 2015 SAR is here [they are dated weird]:

https://fas.org/man/eprint/F35-sar-2016.pdf (0.6Mb) ["As of FY 2017 President's Budget" BUT DEC 2015 - ffsake I give up]


I definitely read it on the LM site, in an LM article linked to a test summary. I have it ... But on a drive that died in April 2017. .... Doh!

Edit - unrefuelled endurance test, cross country, something like Seattle to a southern state. I remember it was not a direct track.

Re: F-35 internal fuel, range

Unread postPosted: 21 Jan 2018, 05:24
by steve2267
You are claiming, then, a max endurance fuel burn of 2800lb/hr when nominal cruise is on the order of 5000-5300lb/hr.

Re: F-35 internal fuel, range

Unread postPosted: 21 Jan 2018, 06:12
by element1loop
steve2267 wrote:You are claiming, then, a max endurance fuel burn of 2800lb/hr when nominal cruise is on the order of 5000-5300lb/hr.


Now don't go being a schmartie, ask yourself, what exactly constitutes your pseudo-defined "nominal cruise" rate?

What weight?
What altitude?
What ISA conditions, at alt?
Most of all, EXACTLY what TAS?

You don't know.

Spurts can speak on those, and relate it to best endurance speed, and implicatons, if he wishes. Not me, I don't burrow that deep, and I'm absolutely sure that you don't.

I claim nothing, except the 5.7 hr unrefuelled endurance test result, sans condiions, sans best endurance speed, or track distance.

And nor are you, as you can't actually put subsubstance to what is this "nominal cruise speed" flow rate, and the conditions of it, let alone define how or why you adopted that nebulous fuel flow for it, that is little more than imaginitive invention.

Re: F-35 internal fuel, range

Unread postPosted: 21 Jan 2018, 06:34
by spazsinbad
element1loop wrote:
spazsinbad wrote:That F-35 test is probably in the F-35 SAR report for that year (on later) - do we assume it is unrefueled/ARFed? Report could be in bigwig text submission to US Congress about F-35 progress? Dec 2015 SAR is here [they are dated weird]:

https://fas.org/man/eprint/F35-sar-2016.pdf (0.6Mb) ["As of FY 2017 President's Budget" BUT DEC 2015 - ffsake I give up]


I definitely read it on the LM site, in an LM article linked to a test summary. I have it ... But on a drive that died in April 2017. .... Doh!

Edit - unrefuelled endurance test, cross country, something like Seattle to a southern state. I remember it was not a direct track.

Vaguely (& I stress VAGUE) I recall some 'cross-country tests before the first Atlantic Crossing which did not happen because of the 'take-off fire at Eglin AFB' which was in 23 Jun 2014. Perhaps further flights cross-country done later?

Re: F-35 internal fuel, range

Unread postPosted: 21 Jan 2018, 06:51
by Dragon029
I don't believe that the 5.7 hour flight or such was unrefueled; we've heard here before that an F-35B burns about 85ppm at max endurance - even if we assume that could drop to 75ppm for the A model, that still leaves a max endurance of a little over 4 hours, with zero fuel reserve and assuming that the tanks are initially topped off at altitude.

Re: F-35 internal fuel, range

Unread postPosted: 21 Jan 2018, 07:07
by element1loop
spazsinbad wrote:
element1loop wrote:
spazsinbad wrote:That F-35 test is probably in the F-35 SAR report for that year (on later) - do we assume it is unrefueled/ARFed? Report could be in bigwig text submission to US Congress about F-35 progress? Dec 2015 SAR is here [they are dated weird]:

https://fas.org/man/eprint/F35-sar-2016.pdf (0.6Mb) ["As of FY 2017 President's Budget" BUT DEC 2015 - ffsake I give up]


I definitely read it on the LM site, in an LM article linked to a test summary. I have it ... But on a drive that died in April 2017. .... Doh!

Edit - unrefuelled endurance test, cross country, something like Seattle to a southern state. I remember it was not a direct track.

Vaguely (& I stress VAGUE) I recall some 'cross-country tests before the first Atlantic Crossing which did not happen because of the 'take-off fire at Eglin AFB' which was in 23 Jun 2014. Perhaps further flights cross-country done later?


I'll see if i can locate it this week, the tests happened, and were unrefueled endurance. I was quite astounded when I read it.

Re: F-35 internal fuel, range

Unread postPosted: 21 Jan 2018, 07:20
by spazsinbad
How 'bout this one - but refueling....: viewtopic.php?f=22&t=28905&p=346380&hilit=Atlantic+test+endurance#p346380
"On June 29, 2016, a group of F-35Bs landed in the UK... [Royal Air Force Sqn Ldr Hugh Nichols, & USMC Col Richard Rusnok & Maj. Jack Cronan, all from VMFAT-501 at Marine Corps Air Station Beaufort, South Carolina] ...They also practiced their flight across the Atlantic Ocean through endurance flights of five hours, including a refueling exercise...." https://www.f35.com/in-depth/detail/beh ... -riat-2016

Re: F-35 internal fuel, range

Unread postPosted: 21 Jan 2018, 07:30
by element1loop
Dragon029 wrote:I don't believe that the 5.7 hour flight or such was unrefueled; we've heard here before that an F-35B burns about 85ppm at max endurance - even if we assume that could drop to 75ppm for the A model, that still leaves a max endurance of a little over 4 hours, with zero fuel reserve and assuming that the tanks are initially topped off at altitude.


I would not be so sure dragon, that B may be describing the flow rate at indicated best endurance speed, but was the jet at the best specific fuel consumption altitude when doing it?

The difference between most efficient alt and conditions can be greater than 100% of that reported rate with a turbine.

Right?

I presume you are current or recent RAAF pilot. So is that not correct?

What I know is, what I read, as detailed above.

Now would formal testing not optimise all parameters and conditions for that 5.6 and 5.7? Is that what two tests are attempting to do?



I'll try to locate the page from my other 'puter during week, on phone now.

Re: F-35 internal fuel, range

Unread postPosted: 21 Jan 2018, 07:31
by steve2267
Yeah, I was wrong. 0.85M burning 5400pph (90ppm) with internal ordnance. No altitude was mentioned; 30's at standard ISA conditions would seem reasonable from everything I've seen written / discussed.

sprstdlyscottsmn wrote:Specifically it was .75M, 32,000ft, 4,600pph (76.7ppm), with 2500lb tactical loadout internal.


0.75M seems more like a max endurance airspeed. I suppose max endurance might be as low as 0.6M? But if the Bee burns around 4600pph @ 0.75M... a max endurance fuel burn of 2800pph (ish) would be phenomenal. If you can document it, I'm sure Spurts would be interested.

Re: F-35 internal fuel, range

Unread postPosted: 21 Jan 2018, 07:34
by element1loop
spazsinbad wrote:How 'bout this one - but refueling....: viewtopic.php?f=22&t=28905&p=346380&hilit=Atlantic+test+endurance#p346380
"On June 29, 2016, a group of F-35Bs landed in the UK... [Royal Air Force Sqn Ldr Hugh Nichols, & USMC Col Richard Rusnok & Maj. Jack Cronan, all from VMFAT-501 at Marine Corps Air Station Beaufort, South Carolina] ...They also practiced their flight across the Atlantic Ocean through endurance flights of five hours, including a refueling exercise...." https://www.f35.com/in-depth/detail/beh ... -riat-2016


Nah, it was a formal test program CONUS endurance test.

Re: F-35 internal fuel, range

Unread postPosted: 21 Jan 2018, 07:58
by element1loop
steve2267 wrote:Yeah, I was wrong. 0.85M burning 5400pph (90ppm) with internal ordnance. No altitude was mentioned; 30's at standard ISA conditions would seem reasonable from everything I've seen written / discussed.

sprstdlyscottsmn wrote:Specifically it was .75M, 32,000ft, 4,600pph (76.7ppm), with 2500lb tactical loadout internal.


0.75M seems more like a max endurance airspeed. I suppose max endurance might be as low as 0.6M? But if the Bee burns around 4600pph @ 0.75M... a max endurance fuel burn of 2800pph (ish) would be phenomenal. If you can document it, I'm sure Spurts would be interested.


For context, in civil high bypass turbines (airliners or business jets) 32,000 ft is typically the highest fuel flow rate (most inefficient alt for best endurance in FLs) but instead it is the best speed alt.

However, the lowest flow rate and best endurance speed, is usually between 40 and 45 k ft, and even higher for lear or concord.

So 32 k ft is the worst possible alt for rate efficency (spec consump) for those engines.

Now correct me if I am wrong, but the F-135 is a high bypass design, with an AB,l lmited by design to sub Mach 1.6?

I do not see why 32k would not also be the most inefficient flight level alt for F-135 endurance speed, as well.

Try 50k ft.

Re: F-35 internal fuel, range

Unread postPosted: 21 Jan 2018, 07:59
by spazsinbad
And this by the AmiableButler: viewtopic.php?f=22&t=15455&p=269752&hilit=Atlantic+Yuma#p269752
F-35B set to make international debut at RIAT, Farnborough
16 Apr 2014 Amy Butler

"...But the programme has been preparing for the extended trip across the Atlantic. On 25 February, a joint sortie by AF-6 and BF-18 – F-35A and B models, respectively – completed a 5.7h mission.... [Yeahbut nobut yeahbut - ARF?]

Source: http://www.flightglobal.com/news/articl ... gh-398334/

Re: F-35 internal fuel, range

Unread postPosted: 21 Jan 2018, 08:34
by element1loop
spazsinbad wrote:And this by the AmiableButler: viewtopic.php?f=22&t=15455&p=269752&hilit=Atlantic+Yuma#p269752
F-35B set to make international debut at RIAT, Farnborough
16 Apr 2014 Amy Butler

"...But the programme has been preparing for the extended trip across the Atlantic. On 25 February, a joint sortie by AF-6 and BF-18 – F-35A and B models, respectively – completed a 5.7h mission.... [Yeahbut nobut yeahbut - ARF?]

Source: http://www.flightglobal.com/news/articl ... gh-398334/


Best endurance speed is not only a speed, it is the most efficient speed, at the most burn efficent altitude, for the prevailing ISA conditions, and weight.

Can't have one, and not the other, and call it meaningful.

It consists of correct speed AND correct altitude.

If you have just one, you have not got best endurance data, at all.

This would not be news to pilots in here, but I'm sure it is to most article writers.

So I seriouly doubt a transit flight was at either the optimal speed or optimal altitude for max endurance.

It was a transit with an exercise scheduled.

Nothing more.

An actual test program fight will have gotten clearence to track at correct altitude and correct TAS, and the track they wanted.

HUGE difference.

Re: F-35 internal fuel, range

Unread postPosted: 21 Jan 2018, 08:45
by spazsinbad
Perhaps if you can give more clues for this 'F-35 test flight for endurance' may be found. We only get close - but no cigar.

URL will find all F-35 'flight test updates' at LM CODE ONE: http://www.codeonemagazine.com/articles ... ategory=24

Re: F-35 internal fuel, range

Unread postPosted: 21 Jan 2018, 09:44
by element1loop
spazsinbad wrote:Perhaps if you can give more clues for this 'F-35 test flight for endurance' may be found. We only get close - but no cigar.

URL will find all F-35 'flight test updates' at LM CODE ONE: http://www.codeonemagazine.com/articles ... ategory=24


As I remember (for what that's worth) I read it around very early 2017, while reading over testing progress updates, from mid and late 2016.

Presumably these were part of the final post production tests to solidify data for certification purposes, and before 3i install, or Marines IOC.

But that's the period I intend to search this week.

Re: F-35 internal fuel, range

Unread postPosted: 21 Jan 2018, 13:09
by optimist
A lot of this stuff seems to be mandatory speed and alt test sets. wasn't there a test change, where the f-35 was allowed to fly at an efficient alt, to get the mission over a KPP threshold limit.

The other question to ask, if if they really want the true numbers released? Or are they going to make stuff up?

Re: F-35 internal fuel, range

Unread postPosted: 21 Jan 2018, 13:53
by element1loop
optimist wrote:A lot of this stuff seems to be mandatory speed and alt test sets. wasn't there a test change, where the f-35 was allowed to fly at an efficient alt, to get the mission over a KPP threshold limit.

The other question to ask, if if they really want the true numbers released? Or are they going to make stuff up?


Spaz requoted that process a page or so back, earlier today.

As for second guessing data, well, the program is remarkably open to scrutiny.

What I do know is that turbofans are fuel guzzlers (but fast) at FL310 thru FL330.

So any data or model-analysis of 'endurance', in that FL range, will provide the opposite end of the endurance fuel-sipping spectrum, in terms of reported fuel-flow rate.

So what do we really know, if alt is not given?

Which is why I found the LM reported unrefuelled endurance of 5.7 hrs quite an astonishing insight.

That is one very efficient engine (when flown within it's efficiency sweet-spot).

Re: F-35 internal fuel, range

Unread postPosted: 21 Jan 2018, 14:52
by optimist
Ok thanks I missed that. It was a good example of alt and the individual aircraft's sweet spot, affecting range.

I'm not trying to get outside the group on this, I don't mind either way. I'm sure there would be better data on the trip, than the few lines.
Unless it was specifically stated, It's unusual to run planes to be on the low side in fuel. Normally on ocean crossings. They fly with a tanker, taking constant sips. On a path, so as always to be in range of a divert field. Maintaining enough fuel to divert. It might have been a 5.7hr flight, but It probably wasn't on one tank.

Re: F-35 internal fuel, range

Unread postPosted: 21 Jan 2018, 15:57
by steve2267
element1loop wrote:What I do know is that turbofans are fuel guzzlers (but fast) at FL310 thru FL330.


Wow. I did not know this. So you are saying that a turbofan "guzzles" fuel between 31000 and 33000 ft? But not, say, at 28,000 or at 37,000? And that a turbofan burns the least amount of fuel at around 45,000? So there is actually a peak in fuel burn right in that 31-33000 altitude ban. Huh. I never would have guessed.

Can you explain why this is?

Regarding bypass ratio, the F135 has a higher bypass ratio for fighter-type aircraft, but it is certainly not considered a high bypass ratio gas turbine ala commercial aircraft engines. It may very well be the highest bypass ratio yet flown in a tactical combat aircraft, but that is an educated guess on my part.

Re: F-35 internal fuel, range

Unread postPosted: 21 Jan 2018, 21:24
by spazsinbad
A regular 'approximately five hour flight' for the F-35s seems to be from Eglin AFB, Florida to Edwards AFB, California. Perhaps flights to/from were made for this ENDURANCE TEST FLIGHT WITHOUT AERIAL REFUELLING? I woke up to guess.

Re: F-35 internal fuel, range

Unread postPosted: 21 Jan 2018, 22:53
by optimist
spazsinbad wrote:A regular 'approximately five hour flight' for the F-35s seems to be from Eglin AFB, Florida to Edwards AFB, California. Perhaps flights to/from were made for this ENDURANCE TEST FLIGHT WITHOUT AERIAL REFUELLING? I woke up to guess.

They could have do that on one tank, as there would have been numerous divert fields on the way. It's the ocean crossings, like when we go to flags. Or when the SH were delivered. There were stories at the time.

Re: F-35 internal fuel, range

Unread postPosted: 21 Jan 2018, 23:21
by element1loop
spazsinbad wrote:A regular 'approximately five hour flight' for the F-35s seems to be from Eglin AFB, Florida to Edwards AFB, California. Perhaps flights to/from were made for this ENDURANCE TEST FLIGHT WITHOUT AERIAL REFUELLING? I woke up to guess.


Good try. That would make sense, east to west, but I would be very surprised if they did not track at near ceiling to get above most of the headwind to shorten track distance, and thus allow use of a higher transit speed.

Re: F-35 internal fuel, range

Unread postPosted: 21 Jan 2018, 23:55
by quicksilver
The endurance flight in 2014 was a pre-translant requirement for the movement to the UK for RIAT/Farn (which was eventually cancelled in the wake of the F-35A fire on takeoff at Eglin). I've forgotten what drove the requirement but it was not formal DT flight test activity. IIRC it was also flown at or near planned translant transit speeds and altitudes and utilized AAR at some point in the flight. How do we know this? Because an F-35B cannot stay aloft for that amount of time without it.

Bar napkin analysis says start with ~13,5K# of JP; as a wag, let's subtract 1.5K# for min fuel on deck, and another 1.3K# for start, taxi and takeoff; that leaves 10.7K# of JP to play with. If we are super crazy, and grossly generous (and in error) let's say the jet will burn on average 3K#/hr;that's a 3.6ish hr sortie duration. We believe (from the sum of public reports) that FF at typical military altitudes and profiles for transoeanic movement will be somewhere in the 4.5K-5.5.K#/hr, but let's split the difference and say 5K#/hr. That's a 2.1hr sortie duration.

So, what is the debate about?

Re: F-35 internal fuel, range

Unread postPosted: 22 Jan 2018, 01:32
by element1loop
steve2267 wrote:
element1loop wrote:What I do know is that turbofans are fuel guzzlers (but fast) at FL310 thru FL330.


Wow. I did not know this. So you are saying that a turbofan "guzzles" fuel between 31000 and 33000 ft? But not, say, at 28,000 or at 37,000? And that a turbofan burns the least amount of fuel at around 45,000? So there is actually a peak in fuel burn right in that 31-33000 altitude ban. Huh. I never would have guessed.

Can you explain why this is?

Regarding bypass ratio, the F135 has a higher bypass ratio for fighter-type aircraft, but it is certainly not considered a high bypass ratio gas turbine ala commercial aircraft engines. It may very well be the highest bypass ratio yet flown in a tactical combat aircraft, but that is an educated guess on my part.


It's complicated, and I'm no expert, so I will keep it simple.

I'm referring to Flight Levels operation, above 29k ft.

Fuel flow rate is highly variable when you maintain speed, but change altitude.

It follows a typical flow curve in modern efficient high-bypass turbofans.

Their maximum speed, and also max flow rate typically occurs around the FL320 area, +/- 2k ft.

At around their ceiling, they're slowest, but burn as little as half the fuel.

The burn is much more economical and (ignoring head or tail winds) provides MUCH better range, and endurance peformance , than at at FL320.

So as much as about 40% more range, but at about 75 to 100 kt lower speed.

Or about 20% lower speed, and 20% longer transit time, maximising range by about 40%, over what you get at FL320.

Pilots like speed, fighter pilots especially, so rarely pay attention to efficient flight regimes, or probably even know how to maximise endurance (and loiter speed is different again, typically at lower alt).

Who wants to fly at 375 kt at 45 k ft, in an F-35, when you could do 550 kts at a lower alt (and use 40% more fuel)?

You don't pay the fuel bill!

So you go fast. And other reasons.

But actual endurance requires low speed and flight near to ceilings, to reduce drag, which reduces fuel burn required to overcome the lower drag and maintain constant speed, that is safely above a high-speed stall, which rises with alt rise (and thus defines the ceiling level).

Drag increases non-linearly with linear rise in speed.

So reducing speed makes drag plumet, thus fuel requirement plumets to, and you need less oxygen to combust.

There is a point where small wings in thin air becomes unstable, producing high speed stall. So you can't go too high, nor too slow, without coming unstuck.

But 50 k ft is also oxygen poor, so the jet needs enough speed to get enough oxygen into inlets, to still burn that lower fuel rate demand, allowed via lower drag, due thinner air.

There is a sweet spot for all jets. Where internal engine efficency design optimisations, and available oxygen (air speed), and thinness of air on airframe (altitude), coincide for best endurance.

And another set for best range speed for it's alt.

They do not coincide.

If you don't know these, and "fly by the numbers", you will never achieve best endurance, or the best range.

Fighter pilots tend to want to do neither much.

(If you want to free up operational budgets, just make your pilots use the most efficient speed and alt ... like auto pilots do for airliners ... yes, they will hate you ... Bad).

At FL320 oxygen is comparsively rich, so you can shove more fuel in and still burn it all, and thus overcome the drag of denser more humid air, thus go much faster, and this coincides with best-speed altitude. Your jet goes like a scalded cat ... IF ... the engine was optimised to operate there (thus F-15C out accel F-16C at plus 30 k ft).

So engine optimisation and aircraft shape has a huge impact on high alt endurance.

We don't know what alt the F-35 is optimised for.

Big wings are great for thin air at a lower endurance speed.

The stubbie does not have that.

But a short wing equates to even lower drag, and higher cruise and endurance speed.

But higher cruise speed actually overcomes the disadvantage (higher stall speed) of a smaller wing, at high altitude (some what).

But an extremely clean shape does the same, also. Thus further increasing cruise and endurance speeds at high alt, thus probably totally negating the downsides of the smaller wing.

And further, the wing area and body lift were maximised for F-35, thus making it able to really perform at very high altitude (predictably much better than any teen fighter can).

So we can expect an unprecidented high cruise, plus very high endurance speed, near top of envelope.

Thus best endurance speed should exhibit outstanding (unheard of) range pertormance, also.

In short, it's a good jet.

Actual endurance time, endurance speed, and endurance track-distance range, will ALL predictably re-write what strikefighters can do.

Contrary to popular opinion.

In theory.

Re: F-35 internal fuel, range

Unread postPosted: 22 Jan 2018, 01:42
by element1loop
quicksilver wrote:So, what is the debate about?


Test results of actual observed baseline max endurance, at non-typical military altitudes and profiles. :mrgreen:


btw, officially, reserves are 2.5 k lb.

Re: F-35 internal fuel, range

Unread postPosted: 22 Jan 2018, 02:46
by quicksilver
1) "It's complicated..."

No, it's not.

2) "I'm no expert..."

Clearly, not about military tacair. So, recommend you stick to stuff you know.

3) "Pilots like speed, fighter pilots especially, so rarely pay attention to efficient flight regimes, or probably even know how to maximise endurance (and loiter speed is different again, typically at lower alt)."

See #2.

4) "If you don't know these, and "fly by the numbers", you will never achieve best endurance, or the best range."

True. But, of course, military mission profiles are widely variable and highly circumstantial. Best endurance or best range are not always the goal of training, nor in many real-world circumstances, practical. When practical, they are routine. Such knowledge is part of primary flight training academics 101 -- the instructional curriculum in Primary at any military flight school. It is reinforced in the strike pipeline if one gets jets, and in-detail in the curriculum for whatever TMS one is selected to fly in the operating forces. You think the guys who are flying 4 hour transits to from their assigned CAPs on the other side of the planet dont know what max endurance or max range alphas are for their jets (at whatever altitude they are assigned)? How about Naval Aviators 'on the ladder' for their 'C' time? See #2 and #3.

5) "Fighter pilots tend to want to do neither much."
Do you base this observation any first-hand experience, or is this just more rectal semantics? See #2, #3 and #4.

Re: F-35 internal fuel, range

Unread postPosted: 22 Jan 2018, 02:48
by quicksilver
element1loop wrote:
quicksilver wrote:So, what is the debate about?


Test results of actual observed baseline max endurance, at non-typical military altitudes and profiles. :mrgreen:


btw, officially, reserves are 2.5 k lb.


For which variant and which service in which countries?

Re: F-35 internal fuel, range

Unread postPosted: 22 Jan 2018, 04:01
by spazsinbad
I'm with 'QS' - no need for 'fighter pilot' derogatory comments. Naval Pilots especially know some range/endurance numbers for their aircraft by being quizzed every morning about their NATOPS. I was initially trained by RAAF and they have similar quizzes at morning briefing. You BETCHA pilots know their aircraft - if they don't they don't get to fly in it.

Attached PDF of three pages shows BINGO Fuel Endurance/Range for the TA-4J/TA-4F (two different engines) PILOT PCL.

Re: F-35 internal fuel, range

Unread postPosted: 22 Jan 2018, 15:45
by steve2267
element1loop wrote:
steve2267 wrote:
element1loop wrote:What I do know is that turbofans are fuel guzzlers (but fast) at FL310 thru FL330.


Wow. I did not know this. So you are saying that a turbofan "guzzles" fuel between 31000 and 33000 ft? But not, say, at 28,000 or at 37,000? And that a turbofan burns the least amount of fuel at around 45,000? So there is actually a peak in fuel burn right in that 31-33000 altitude ban. Huh. I never would have guessed.

Can you explain why this is?

Regarding bypass ratio, the F135 has a higher bypass ratio for fighter-type aircraft, but it is certainly not considered a high bypass ratio gas turbine ala commercial aircraft engines. It may very well be the highest bypass ratio yet flown in a tactical combat aircraft, but that is an educated guess on my part.


It's complicated, and I'm no expert, so I will keep it simple.

I'm referring to Flight Levels operation, above 29k ft.

Fuel flow rate is highly variable when you maintain speed, but change altitude.

It follows a typical flow curve in modern efficient high-bypass turbofans.

Their maximum speed, and also max flow rate typically occurs around the FL320 area, +/- 2k ft.

At around their ceiling, they're slowest, but burn as little as half the fuel.

The burn is much more economical and (ignoring head or tail winds) provides MUCH better range, and endurance peformance , than at at FL320.

So as much as about 40% more range, but at about 75 to 100 kt lower speed.

Or about 20% lower speed, and 20% longer transit time, maximising range by about 40%, over what you get at FL320.

Pilots like speed, fighter pilots especially, so rarely pay attention to efficient flight regimes, or probably even know how to maximise endurance (and loiter speed is different again, typically at lower alt).

Who wants to fly at 375 kt at 45 k ft, in an F-35, when you could do 550 kts at a lower alt (and use 40% more fuel)?

You don't pay the fuel bill!

So you go fast. And other reasons.

But actual endurance requires low speed and flight near to ceilings, to reduce drag, which reduces fuel burn required to overcome the lower drag and maintain constant speed, that is safely above a high-speed stall, which rises with alt rise (and thus defines the ceiling level).

Drag increases non-linearly with linear rise in speed.

So reducing speed makes drag plumet, thus fuel requirement plumets to, and you need less oxygen to combust.

There is a point where small wings in thin air becomes unstable, producing high speed stall. So you can't go too high, nor too slow, without coming unstuck.

But 50 k ft is also oxygen poor, so the jet needs enough speed to get enough oxygen into inlets, to still burn that lower fuel rate demand, allowed via lower drag, due thinner air.

There is a sweet spot for all jets. Where internal engine efficency design optimisations, and available oxygen (air speed), and thinness of air on airframe (altitude), coincide for best endurance.

And another set for best range speed for it's alt.

They do not coincide.

If you don't know these, and "fly by the numbers", you will never achieve best endurance, or the best range.

Fighter pilots tend to want to do neither much.

(If you want to free up operational budgets, just make your pilots use the most efficient speed and alt ... like auto pilots do for airliners ... yes, they will hate you ... Bad).

At FL320 oxygen is comparsively rich, so you can shove more fuel in and still burn it all, and thus overcome the drag of denser more humid air, thus go much faster, and this coincides with best-speed altitude. Your jet goes like a scalded cat ... IF ... the engine was optimised to operate there (thus F-15C out accel F-16C at plus 30 k ft).

So engine optimisation and aircraft shape has a huge impact on high alt endurance.

We don't know what alt the F-35 is optimised for.

Big wings are great for thin air at a lower endurance speed.

The stubbie does not have that.

But a short wing equates to even lower drag, and higher cruise and endurance speed.

But higher cruise speed actually overcomes the disadvantage (higher stall speed) of a smaller wing, at high altitude (some what).

But an extremely clean shape does the same, also. Thus further increasing cruise and endurance speeds at high alt, thus probably totally negating the downsides of the smaller wing.

And further, the wing area and body lift were maximised for F-35, thus making it able to really perform at very high altitude (predictably much better than any teen fighter can).

So we can expect an unprecidented high cruise, plus very high endurance speed, near top of envelope.

Thus best endurance speed should exhibit outstanding (unheard of) range pertormance, also.

In short, it's a good jet.

Actual endurance time, endurance speed, and endurance track-distance range, will ALL predictably re-write what strikefighters can do.

Contrary to popular opinion.

In theory.


(Since people can edit (or delete) their posts, quoted above for all posterity.)

Thank you for your explanation.

When you resorted to name calling and insulting, belittling comments to some of my other posts, I wondered if you really know of what you write. IMO, this last posts clinches it for me: you know just enough to be dangerous.

Re: F-35 internal fuel, range

Unread postPosted: 22 Jan 2018, 21:36
by usafr
Hey Guys! :-)

"Who wants to fly at 375 kt at 45 k ft, in an F-35, when you could do 550 kts at a lower alt (and use 40% more fuel)?"

No one in this debate seems to be aware of the difference between 1. Indicated Air Speed (IAS) and 2. True Air Speed (TAS).

I only say this because no one has mentioned either one, despite many opportunities to do so.

IAS (and drag) decreases with altitude (because air "thins" with altitude = few air molecules per fixed volume ).

If thrust is added to maintain constant TAS and AOA is increased to maintain lift (to keep Jet in the air, duh) as Jet climbs then, IAS will continue to decline until wing stalls or the engine runs out of additional thrust to overcome drag.

Airplanes display IAS in cockpit and on HMD because IAS is an indicator of how the jet will behave "in the air it is in."

TAS is important to determine "how far the Jet will fly over the ground", +/- wind.

Any debate about "range, endurance, etc" is uninformed if it does not first understand delta IAS v TAS.

Respectfully,

David Austin
Software Developer
AOA Simulations
F-35B Lightning II for X-Plane Flight Simulator

Re: F-35 internal fuel, range

Unread postPosted: 24 Jan 2018, 06:00
by element1loop
steve2267 wrote: (Since people can edit (or delete) their posts, quoted above for all posterity.)

Thank you for your explanation.

When you resorted to name calling and insulting, belittling comments to some of my other posts, I wondered if you really know of what you write. IMO, this last posts clinches it for me: you know just enough to be dangerous.



You asked for an explanation of why high-bypass turbines characteristically have a higher fuel-flow rate between FL310 and FL330, than at other altitudes.

For the purposes of the reply, and in the context of the question you've asked, the answer is entirely correct.

I'm quite satisfied that what I've written explains it sufficiently to answer you're question.

The more salient question is, why didn't you know any of this?

I take a low view of your comments in particular, simply because they are so consistently low-brow. Lift you're game when commenting - the onus is on you.

But if you want to prance around and talk rubbish, than that's what's being "preserved" here ... for all posteria.

Re: F-35 internal fuel, range

Unread postPosted: 24 Jan 2018, 06:03
by element1loop
usafr wrote:Hey Guys! :-)

"Who wants to fly at 375 kt at 45 k ft, in an F-35, when you could do 550 kts at a lower alt (and use 40% more fuel)?"

No one in this debate seems to be aware of the difference between 1. Indicated Air Speed (IAS) and 2. True Air Speed (TAS).

I only say this because no one has mentioned either one, despite many opportunities to do so.

IAS (and drag) decreases with altitude (because air "thins" with altitude = few air molecules per fixed volume ).

If thrust is added to maintain constant TAS and AOA is increased to maintain lift (to keep Jet in the air, duh) as Jet climbs then, IAS will continue to decline until wing stalls or the engine runs out of additional thrust to overcome drag.

Airplanes display IAS in cockpit and on HMD because IAS is an indicator of how the jet will behave "in the air it is in."

TAS is important to determine "how far the Jet will fly over the ground", +/- wind.

Any debate about "range, endurance, etc" is uninformed if it does not first understand delta IAS v TAS.

Respectfully,

David Austin
Software Developer
AOA Simulations
F-35B Lightning II for X-Plane Flight Simulator


You weighed-in with superfluous BS without even reading the prior discussion.

I wrote this earlier:

See link
viewtopic.php?p=386342&sid=02241efe8346150b527a17711315076b#p386342

"What weight?
What altitude?
What ISA conditions, at alt?
Most of all, EXACTLY what TAS?"


Yet another unctuous person who pretends to have some contrived nit-picking 'point' to critique ... but actually doesn't.

Re: F-35 internal fuel, range

Unread postPosted: 25 Jan 2018, 01:07
by spazsinbad
I'll guess this report is a GOOD REASON why internal fuel/range/endurance is important - even the F-35A gets scratched.
FY 17 DOD PROGRAMS [DOT&E] F-35 Joint Strike Fighter (JSF)
Pub Jan 2018 for 2017 DOT&E

"F-35B and F-35C Air Refueling Restrictions page numbered 58 (physical page 28)
-- Both variants use an air refueling probe which is designed with an intentional weak link to protect the probe. The probe tips are breaking too often, resulting in squadrons imposing restrictions on air refueling. The program is still investigating this problem."

Source: http://www.dote.osd.mil/pub/reports/FY2 ... f35jsf.pdf (0.5Mb)

Re: F-35 internal fuel, range

Unread postPosted: 25 Jan 2018, 05:59
by optimist
The pilots here will be able to say. I've heard it is hard work on the pilot flying a ceiling alt, it's not comfortable on the body. There would be an equivalent canopy pressure chart, to see what they are meaning.

Re: F-35 internal fuel, range

Unread postPosted: 25 Jan 2018, 06:59
by spazsinbad
optimist wrote:The pilots here will be able to say. I've heard it is hard work on the pilot flying a ceiling alt, it's not comfortable on the body. There would be an equivalent canopy pressure chart, to see what they are meaning.

I'll bite but from the peanut gallery (with the manky monkey pilots). Flying fighter jets is not comfortable for anyone most likely and as I have not flown every fighter jet there has been or be to come -whatever- that is just my generalization eh.

To me, reading how the F-35 'flies itself' so the pilot can concentrate on his 'tea & biscuits' strategizing watching over the BIG PICTURE, not having to maneuver harshly most of the time, then with that mythical 'paper bag' over me head I can get along in me pjs & slippers nicely - thank you. :mrgreen: With that out of the way I'll attempt to address your question (but why?).

Yes there is a service ceiling which will be at/below the cabin altitude that requires no pressure suit. Probably there are minor differences in the altitude / cabin altitude differential and a canny pilot should keep an eye on the cabin alt to ensure no hypoxilating is evident or similar UPE. Depending on what one has eaten then there should be no problems at high cabin alts - beware the beans & greens because theys mean farts. However if flying on your lonesome who cares.

Probably most miljets take a long time to get to their service ceilings but of course I generalize. Why go there except on a full test flight schedule? I can recall the ONLY time I EVER took an A4G 'as high as it could go' was ONCE returning from a long navigation flight, climbing out from low level at Broken Hill on direct route to NAS Nowra. Sadly my chase wingman instructor pilot had a generator failure thus popping the RAT, Ram Air Turbine emergency generator and he fell out of the sky consequently. We were above 40,000 feet but with plenty of gas (because he was an instructor USN LEUT) he decided to hot foot it back to Nowra TOOT SWEET because we had been in the air for a very long time indeed. (I'd have to check my logbook for details.) I decided to continue as per flight plan so that the fuel figures could be checked (I forget now).


Re: F-35 internal fuel, range

Unread postPosted: 25 Jan 2018, 08:16
by spazsinbad
I remembered a not so memorable test flight as a sprog midshipman sitting in the right hand Observer seat of the Sea Venom FAW Mk53 with the Squadron AEO (Air Engineer Officer) who years earlier had joined the RAN FAA from another Fleet Air Arm but had little flying time in our neck o the woods. For myself at that time I had only a few Venom hours (with several hundred Vampire hours) and it was for 'safety' that I went along on behest of our VC-724 Senior Pilot (XO).

Being a test flight of the pressurization system amongst other components we went up towards the service ceiling (what that is I would have to look up) however with a minimal swept wing and more power than a dual Vampire we climbed up fairly quickly. BTW the right hand seat has NO FLIGHT CONTROLS whatsoever (Observer looked in a hooded radar screen).

Well the canopy seal failed at some high height (exactly how high I forget now) but it was HIGH indeed. The AEO being of a mechanical bent or HYPOXIC wanted to 'check out the system' (how he would do that beats me). Meanwhile I just SCREAMED at him to get down below 10,000 feet NOW! I was a middie and he an LCDR but I was not 'taking it anymore'. Perhaps I could have leaned over after loosening my straps to push the control column forward but there is a time of useful consciousness at work here. Whatever. Thank goodness my intrepid pilote decided it was a good idea to get down fast and we did. SIGH of Relief and we more or less moseyed back to NAS Nowra (with me telling the SP "never again").

What did that fast decompression feel like? Just the same as in the pressure chamber learning at Point Cook during Basic Flying Training. IF we had have stayed up there probably we would have been in LahLahLand fairly quickly like an early RAAF F-A-18A Hornet sprog pilot taking off his oxy mask during a climb to high altitude and never putting it back on as he flew on with wingman radioing with out effect. Pilot/Aircraft crashed somewhere, to be found in a big hole years later.

Re: F-35 internal fuel, range

Unread postPosted: 25 Jan 2018, 15:43
by mixelflick
So I read everything and... she has great range :)

Especially for her size. 18,000 plus pounds of fuel and low drag/great lift in a combat loaded scenario. I still get people on other boards wanting to compare clean Flankers, etc to the F-35's stats. Why is it so hard to get these people to think out of "airshow configuration"?

Re: F-35 internal fuel, range

Unread postPosted: 25 Jan 2018, 18:09
by blindpilot
spazsinbad wrote:...
Yes there is a service ceiling which will be at/below the cabin altitude that requires no pressure suit. Probably there are minor differences in the altitude / cabin altitude differential and a canny pilot should keep an eye on the cabin alt to ensure no hypoxilating is evident or similar UPE. Depending on what one has eaten then there should be no problems at high cabin alts - beware the beans & greens because theys mean farts. However if flying on your lonesome who cares.

Probably most miljets take a long time to get to their service ceilings but of course I generalize. Why go there except on a full test flight schedule? I can recall the ONLY time I EVER took an A4G 'as high as it could go' was ONCE returning from a long navigation flight, climbing out from low level at Broken Hill on direct route to NAS Nowra....


I had a similar opportunity in the Southeast US, where coming home from a T-38 cross country, the weather started going down hill. (as it does in that area) Having a young bride nine months pregnant, I was anxious to get home. Center cleared me "above" whatever was the floor those days (? FL 400?) and I raced to see how fast a thunderstorm can can climb. I made it, but also decided that thunderstorms can climb faster than ANY "go fast jet," and never tried that again. All I ran into was a bit of pressure breathing. FYI fighter jets are good up to about 62,000 feet or so (CO2 poisoning risks on decompress, or some such) without needing a pressure suit. You may just have to forcefully exhale.

FWIW,
BP

Re: F-35 internal fuel, range

Unread postPosted: 25 Apr 2019, 17:12
by doge
F-35B pilot Capt. Tyler "Ditch" Bonnett interview.
From around ~8:00
He says ""C" can fly longer more than an hour more than "B"".
"Fuel 20,000lb vs 13,500lb."

other...
Around ~5:30
There is an footage that seems to be F-35B's cockpit viewpoint. (Cockpit installation camera.)
I was the first to see a video of the F-35 cockpit viewpoint.(maybe.) It's super RARE. 8)

Re: F-35 internal fuel, range

Unread postPosted: 25 Apr 2019, 19:06
by blain
doge wrote:F-35B pilot Capt. Tyler "Ditch" Bonnett interview.
From around ~8:00
He says ""C" can fly longer more than an hour more than "B"".
"Fuel 20,000lb vs 13,500lb."

other...
Around ~5:30
There is an footage that seems to be F-35B's cockpit viewpoint. (Cockpit installation camera.)
I was the first to see a video of the F-35 cockpit viewpoint.(maybe.) It's super RARE. 8)


Hmmm. At some point range and payload is going to matter for the Marines, especially in the Pacific. There is only so many big deck amphibs you will be able to operate off from and defensible islands. I'm surprised there is no one in the Marines advocating for a 50/50 mix of Bs and Cs.

Re: F-35 internal fuel, range

Unread postPosted: 25 Apr 2019, 19:19
by sprstdlyscottsmn
The Marines are already getting Cs to operate from CVNs.

Re: F-35 internal fuel, range

Unread postPosted: 25 Apr 2019, 21:27
by spazsinbad
'blain' said above: "Hmmm. At some point range and payload is going to matter for the Marines, especially in the Pacific. There is only so many big deck amphibs you will be able to operate off from and defensible islands. I'm surprised there is no one in the Marines advocating for a 50/50 mix of Bs and Cs." 'shrdlusilyscottie' :mrgreen: replied and I'll reply:
Tankers Tankers Tankers. Doan forgut Ospreys spraying fuel either on ground or in the air to F-35Bs or did you forgat that?

Re: F-35 internal fuel, range

Unread postPosted: 25 Apr 2019, 22:22
by SpudmanWP
The USMC only wanted the B due to austere basing. They were forced to get the C.

Re: F-35 internal fuel, range

Unread postPosted: 25 Apr 2019, 23:27
by Gums
Salute!

My view is that the Marines had an active Harrier Mafia, so the STOVL version resulted. OTOH, they flew F-4 and F-18 jets all along, so the Cee model helped the overall budget by reducing unit cost.

So far, the Cee looks like a winner, and the Hornet jocks are gonna have orgasms when they see the fuel numbers. And do not be surprised when you see Cee birds with external tanks and refueling stuff for their buddies.

Gums opines....

Re: F-35 internal fuel, range

Unread postPosted: 25 Apr 2019, 23:37
by sprstdlyscottsmn
Legacy Hornet drivers are going to be impressed with the F-35B. F/A-18C only has 10,800 internal. The 13,300 on the F-35B is like a Hornet with a centerline.

The F-35C is like an F-14 with drop tanks.

Re: F-35 internal fuel, range

Unread postPosted: 26 Apr 2019, 01:12
by spazsinbad
'Gums' said above: "...And do not be surprised when you see Cee birds with external tanks and refueling stuff for their buddies." But But But - what about the STINGRAY!? EFTs maybe but BUDDY REFUEL? Don't buy it - only if MQ-25 fails.

Re: F-35 internal fuel, range

Unread postPosted: 26 Apr 2019, 01:49
by crosshairs
sprstdlyscottsmn wrote:Legacy Hornet drivers are going to be impressed with the F-35B. F/A-18C only has 10,800 internal. The 13,300 on the F-35B is like a Hornet with a centerline.

The F-35C is like an F-14 with drop tanks.


Minus the speed, acceleration, altitude, maneuverability, or numbers of aams.

Re: F-35 internal fuel, range

Unread postPosted: 26 Apr 2019, 02:19
by sferrin
crosshairs wrote:
sprstdlyscottsmn wrote:Legacy Hornet drivers are going to be impressed with the F-35B. F/A-18C only has 10,800 internal. The 13,300 on the F-35B is like a Hornet with a centerline.

The F-35C is like an F-14 with drop tanks.


Minus the speed, acceleration, altitude, maneuverability, or numbers of aams.


Are you saying you believe a Tomcat could out maneuver an F-35C? Or carry more AAMs?

Re: F-35 internal fuel, range

Unread postPosted: 26 Apr 2019, 03:51
by eloise
crosshairs wrote:Minus the speed, acceleration, altitude, maneuverability, or numbers of aams.

Speed: F-35 cut off at Mach 1.6, F-14D with F-110GE400 limit at Mach 1.8
F-14D.PNG


Acceleration:
F-35, at least A version can accelerate as good as F-16 in the subsonic regime, F-14 acceleration is significantly worse than F-16 (in the test vs
F-16vsF-35-2.jpg


Number of AAMs
F-35 can carry 4-6 more AAM than TomCat
F-35 can carry ramjet Meteor
f-14-053.jpg

f-35.PNG

missile range estimation 2.JPG

Re: F-35 internal fuel, range

Unread postPosted: 26 Apr 2019, 12:47
by mixelflick
With respect to acceleration, I agree with you about the A being superior. But he was likely referring to F-35C, which we know has inferior acceleration (vs. the A, at least).

I honestly don't feel the top speed is all that different, and suspect the F-35 has been cleared out to something greater than Mach 1.6. Perhaps not too far past that, but perhaps 1.8 to close to 2.0. When the new engines get here, top speed will likely remain the same, but range and acceleration will increase substantially.

Even with the current engine, F-35C is much superior to the F-14, B and D models included. As much as I love that old bird, the F-35C is infinitely more capable and will dramatically improve all aspects of naval tac air. Air to air, air to ground, air to everything. In any of those environments, it will not be seen. Or not seen until it's far too late.

F/A-XX has its work cut out for it. It's going to have to improve upon the F-35C's war fighting capabilities by at least 20%. That's going to be a tall order. I'd bet anything the Navy ditches it and just buys up-rated F-35's...

Re: F-35 internal fuel, range

Unread postPosted: 26 Apr 2019, 15:31
by marsavian
I'd bet anything the Navy ditches it and just buys up-rated F-35's.


Agreed, which sacrifice performance for more range as I can't see a separate product being sanctioned while the F-35 line is open and PCA needs development/producing. Their only real chance for something new is a PCA spinoff.

Re: F-35 internal fuel, range

Unread postPosted: 26 Apr 2019, 18:48
by castlebravo
eloise wrote:
missile range estimation 2.JPG


Where are you getting the missile range estimation graph from? I find it hard to believe that a ramjet missile with the intake sticking out in the breeze is going to decelerate at the same rate as an AIM-120 after the motor is out. I also wonder if they account for intake ram drag when calculating the actual thrust at Mach 5+. If ramjets are that awesome for hypersonic missiles, where are all the Mach 5+ AShCMs, and why is everyone clamoring to build a scramjet missile?

Re: F-35 internal fuel, range

Unread postPosted: 26 Apr 2019, 19:23
by blain
You can either carry a lift fan or you can carry 6,000 lbs more fuel and have a larger weapons bay. I seem to remember the Marines doing alright with F-4s in Vietnam and fighting two major wars in the Middle East with Hornets and Intruders. Wars in which they really didn't STOVL.

Now the focus is China. Some people say it might be good to have fighters with range. The Marines say the F-35Bs gives them the option of operating close to the enemy or behind enemy lines from expeditionary bases. It's not World War II when you are both fighting far from home on islands in the South Pacific where the geography and strategy favors seizing islands and establishing bases. If you want to seize and operate from expeditionary airbases you will likely be doing that in the enemy's back yard. TBH - I'd rather punch and jab from close from the end of the opponent's reach than get close to his face and try to slug it out.

Saddam's military might not notice you have an EAB on his territory, but I wouldn't try that against the Chinese when you likely won't need to. If range in fighters is important then the Marines need an adequate mix of fighters with that element. Three squadrons are not enough. If the Marines split the buy they would end up with 210 Bs and 210 Cs.

Re: F-35 internal fuel, range

Unread postPosted: 27 Apr 2019, 00:09
by marsavian
castlebravo wrote:
eloise wrote:
missile range estimation 2.JPG


Where are you getting the missile range estimation graph from? I find it hard to believe that a ramjet missile with the intake sticking out in the breeze is going to decelerate at the same rate as an AIM-120 after the motor is out. I also wonder if they account for intake ram drag when calculating the actual thrust at Mach 5+. If ramjets are that awesome for hypersonic missiles, where are all the Mach 5+ AShCMs, and why is everyone clamoring to build a scramjet missile?


It's a missile simulation.

viewtopic.php?f=44&t=54426

Specifically,

https://jaesan-aero.blogspot.com/2019/0 ... 3.html?m=1

Re: F-35 internal fuel, range

Unread postPosted: 27 Apr 2019, 04:13
by castlebravo
I can't find any details on how he simulated a VFDR, but I wouldn't be surprised if he just plugged in a higher ISP. Reality is far more complex. Ducted rockets have been used in SAMs since at least the 1960's, and in one case (SA-6/SA-11) we have actually seen an older ducted rocket missile get replaced with a modernized version that uses a plain old solid rocket motor. I suspect the key advantage of Meteor is not higher ISP from it being a ducted rocket, but that it uses a Variable Flow Ducted Rocket that allows it to throttle down when appropriate. Unless the VFDR is actually a form of scramjet where the intake air is not decelerated to subsonic velocity, I just don't see Meteor having 3+ times the performance of AIM-120D in every scenario.

If ducted rockets really were that good, everyone and their mom would be using them for their high-end SAMs, and we would have SM-6 Blk III missiles diving down on targets 500+ nmi away while going Mach 6. In reality, we see the exact opposite. A lot of the oldest SAMs built used air breathing engines, and none of the modern ones do. I call that a clue.

Re: F-35 internal fuel, range

Unread postPosted: 27 Apr 2019, 04:59
by eloise
castlebravo wrote:I can't find any details on how he simulated a VFDR, but I wouldn't be surprised if he just plugged in a higher ISP. Reality is far more complex

http://jaesan-aero.blogspot.com/2019/01 ... on-of.html
https://jaesan-aero.blogspot.com/2019/0 ... on-of.html
http://jaesan-aero.blogspot.com/2018/10 ... art-2.html

castlebravo wrote:I just don't see Meteor having 3+ times the performance of AIM-120D in every scenario.

He put AIM-120C-5 in his graph
Secondly, according to various sources, ramjet missiles can improve range by factors of 3 or more
Image
image_260281.jpg


castlebravo wrote:If ducted rockets really were that good, everyone and their mom would be using them for their high-end SAMs, and we would have SM-6 Blk III missiles diving down on targets 500+ nmi away while going Mach 6. In reality, we see the exact opposite. A lot of the oldest SAMs built used air breathing engines, and none of the modern ones do. I call that a clue.

Solid rocket motor has 2 advantages over ramjet:
- Significantly higher initial acceleration
- Can reach higher altitude because their propulsion don't require air
Surface launched missiles has 2 differences from air-launched missiles
- It is easier to increase their size and weight
- They are more limited by radar horizon.
In short, long range is not as important as acceleration and flight ceiling for SAM, and it is easier to increase their size or add a booster so ramjet is not as important for SAM as they are for AAM.

Re: F-35 internal fuel, range

Unread postPosted: 27 Apr 2019, 10:38
by marsavian
sprstdlyscottsmn can also get high range numbers for Meteor with his missile sim with certain assumed parameters.

viewtopic.php?p=414945#p414945

Re: F-35 internal fuel, range

Unread postPosted: 27 Apr 2019, 13:47
by steve2267
I won’t argue range, but am astonished the Meteor is a 6+ Mach missile — and a ramjet at that! They really are working miracles with CFD these days.


/sarc=off

Re: F-35 internal fuel, range

Unread postPosted: 27 Apr 2019, 14:32
by sprstdlyscottsmn
Yeah, I got max range at min thrust.

Re: F-35 internal fuel, range

Unread postPosted: 28 Apr 2019, 01:25
by Gums
Salute!

Did I miss the thread topic?

Besides, why use old-fashioned missiles ?

I got my megawatt laser powered by the magnetohydrodynamic grid of the small rocket motor on station 6. You know, the doofer that strips off electrons and ions and generates more power you can dream of when I activate it.

And BTW, there's always an optimum pounds per mile versus miles required in the time available for my plane that uses JP fuel and gets the missile or laser to the fight. My Stubbie has plenty, and it sips gas..

Gums sends....

Re: F-35 internal fuel, range

Unread postPosted: 06 Jun 2019, 02:04
by doge
F-35 test pilot Tony "Brick" Wilson made remarks that seemed quite important. 8)
From 7:35~

F-35A on station time 2.5 hours.jpg

The F-35A carries about 18,000 lb of fuel internal compared to when I was flying 4th Gen Fighters.

The Legacy F/A-18 carries a little over 10,000 pounds and the Super Hornet carries a little over twelve thousand pounds internal.

Why is this important? Because, with the single engine in that much fuel onboard my on station time is greater.

If I'm flying a max endurance max range type of profile, I'm able to get to two and a half hours of on station time easily out of this aircraft.

"On-station time is 2.5 hours"!! :shock:

I think this is an important number in relation to the mysterious F-35's range (Clear true numbers[km, nmi] not be released. or Classified.) or radius.
I think "2.5 hours on-station time" is very very long. 8) (It's...Long working hours!! :doh: )

Re: F-35 internal fuel, range

Unread postPosted: 06 Jun 2019, 02:16
by spazsinbad
https://www.youtube.com/embed/hmnkcP-sJHk BEST TO USE: https://www.youtube.com/watch?v=hmnkcP-sJHk

LOOKS like '360 degree video' does not work in IE 11 but does in EDGE! so title & link to click on below & the URL works.

360 VIDEO: F-35 Test Pilot Walkaround https://www.youtube.com/watch?v=hmnkcP-sJHk

Without watching video "what does on station time mean"? Where and WHEN does it start from the carrier? Is it overhead?


Re: F-35 internal fuel, range

Unread postPosted: 06 Jun 2019, 04:08
by Dragon029
It'd be interesting to see what range that'd be at from an airbase; it definitely wouldn't be the combat radius, but would this be doing circuits over an airbase? At a training range 50nmi from an airbase? 100nmi? 200nmi?

Re: F-35 internal fuel, range

Unread postPosted: 06 Jun 2019, 05:03
by spazsinbad
Dragon029 wrote:It'd be interesting to see what range that'd be at from an airbase; it definitely wouldn't be the combat radius, but would this be doing circuits over an airbase? At a training range 50nmi from an airbase? 100nmi? 200nmi?

'Brick' is the FIRST PILOT to arrest aboard a CVN with the F-35C - he was the CO of VX-23 until I guess he retired to be an LM F-35 test pilot. My thinking was 'F-35C from carrier' to be overhead ready to 'buster' out to the bogey but the comment is so NEBULOUS that it becomes irrelevant without context. So we can all 'guess away' to own heart's content. No?

For those unwilling to be '360' here it is in the FLAT EARTH look....

Tony 'Brick' Wilson LM Test Pilot F-35 Explained Walkaround 360 https://www.youtube.com/watch?v=5Xn0asyM_-E

UHoh - not even IE 11 shows the FLAT video now so use the URL.


Re: F-35 internal fuel, range

Unread postPosted: 06 Jun 2019, 09:50
by doge
About the "on-station time", I found thing of F-16V. 8) (It looks like the magazine of the Indian Force.)
http://forceindia.net/feature-report/fi ... xcellence/

http://www.vayuaerospace.in/issue/vayu- ... df#page=90
Unparalleled Mission Reach
The F-16 Block 70 with conformal fuel tanks has a mission radius exceeding 1,700 kilometres (km) in an air-to-air configuration carrying four AMRAAMs, two ASRAAMs and two 370 gallon fuel tanks. This yields a 750 km DCA Combat Air Patrol (CAP) with on-station time of more than two hours.

Even with the addition of targeting systems and two 2,000 pound (lb) class Joint Direct Attack Munitions (JDAMs), the F-16 Block 70 has a mission radius exceeding 1,300 km — 30 per cent greater than that of the F-16’s closest competitor. With the optional 300 gallon centreline tank and two 600 gallon wing tanks, the F-16 Block 70’s advantages are even greater.

F-16V [CFT + 370galEFTx2] Total Fuel About 15,000lb-----------This is Roughly(internal 7,000lb + CFT 3,000lb + 370galx2EFT 5,000lb)

The F-16V's DCA/CAP mission, with fuel about 15,000 lbs, it seems have radius is 750km/on-station time is more than 2 hours.
I hope that F-35A is longer than this F-16... (Because, there are more fuel about 3,000lbs than that! :doh: )(desire 8) )

Re: F-35 internal fuel, range

Unread postPosted: 06 Jun 2019, 14:03
by quicksilver
Did I miss it or did they not provide the radius at which the TOS was calculated? You can take off and orbit home plate and generate boo-coo TOS...

Re: F-35 internal fuel, range

Unread postPosted: 06 Jun 2019, 15:51
by mixelflick
I just love the fact it carries so much gas.

For so long, even big US fighters seemed short legged. The F-15 for example: 13.000 or so lbs of fuel vs. most Flankers, up to 25,000lbs. I realize they have different needs (huge country, not much in the way of tankers), but simply carrying more gas makes more sense to me.

LM did a really good job with the internal fuel it packed into the F-22, and a GREAT job with the 18,000lbs in the F-35A, I think 13,000 in the B and 19,000 in the C. The pilots sure seem to appreciate it..

Re: F-35 internal fuel, range

Unread postPosted: 06 Jun 2019, 16:06
by SpudmanWP
doge wrote:I hope that F-35A is longer than this F-16... (Because, there are more fuel about 3,000lbs than that! :doh: )(desire 8) )
Given that the F-35A has a longer Combat Radius in A2G mode vs an F-16 with CFTs and EFTs (600 gal), the F-35A should also out-range it in A2A, especially considering the F-16 in the above example has 370 gal EFTs.

Trd4pNp[1].jpg

Re: F-35 internal fuel, range

Unread postPosted: 06 Jun 2019, 16:32
by mixelflick
Someone once relayed an anecdote as to gas, range and the gun.

Loosely, they asked F-35B/C drivers which they'd prefer: More gas, or a gun? They almost universally wanted more gas. To me, that speaks volumes.

I guess I would too, flying over the ocean with my airfield always moving!

Re: F-35 internal fuel, range

Unread postPosted: 06 Jun 2019, 18:43
by spazsinbad
quicksilver wrote:Did I miss it or did they not provide the radius at which the TOS was calculated? You can take off and orbit home plate and generate boo-coo TOS...

No details are provided. I'll quote it word for word soon..... My 'overhead mother' was just an example with of course many many many many other scenarios that were not provided, including the first mother. In the video at 7:38 the fuel comparison is mentioned. At 8 minutes in he says: "Why is this (the fuel) important. Because with a single engine and that much fuel (18K lbs) onboard my on-station time is greater. If I'm flying a max endurance max range type of profile I'm going to get two - two and a half hours of on-station time easily out of this aircraft."

Re: F-35 internal fuel, range

Unread postPosted: 06 Jun 2019, 21:50
by vilters
Station: Place where trains depart and arrive
On the station: Is a roof.
So he can sit "on the roof" for 2.5 hrs. :devil:

He never said how far the "station" was form his base, so his 2.5 hrs statement is meaningless info. :bang:
As was my joke above. :devil:

Re: F-35 internal fuel, range

Unread postPosted: 06 Jun 2019, 22:20
by wrightwing
vilters wrote:Station: Place where trains depart and arrive
On the station: Is a roof.
So he can sit "on the roof" for 2.5 hrs. :devil:

He never said how far the "station" was form his base, so his 2.5 hrs statement is meaningless info. :bang:
As was my joke above. :devil:

Well, an F-16 with less fuel and a higher DI has a >2hr station time, at 750km. If we use some deductive reasoning, we can conclude that an F-35A will likely have 2.5hrs on station at >750km.

Re: F-35 internal fuel, range

Unread postPosted: 23 Jul 2019, 10:36
by doge
I dug up. 8)
Looks to me as Morten "Dolby" Hanche has revealed quite specific numbers about the F-35 range. 8) (2 years ago but.)
https://www.regjeringen.no/no/tema/fors ... id2353192/ (The language is Norwegian. I used Google Translate.)

That's over 30% of F-16's range...
How long is the range of the F-16? 8) :devil:
The F-35 has the ability to carry weapons and fuel internally. This contributes to the aircraft getting considerably better range than previous aircraft due to less air resistance. In relation to today's Norwegian F-16, we estimate that the F-35 will have a full 30% more range with corresponding weapons load. This design also ensures that the F-35 can fly at maximum speed of 1.6 times the speed of sound (Mach 1.6) even with internal weapons. Older aircraft often have tanks and weapons hanging on the wing or abdomen, which results in high air resistance. It again means that it is almost impossible to achieve the performance (primarily speed and G-load) that is often stated for the type of aircraft. The F-35, which has both fuel and weapon load inside the fuselage, thus has reduced air resistance and consequently better acceleration and maneuverability than older aircraft with similar weapons load.

Re: F-35 internal fuel, range

Unread postPosted: 23 Jul 2019, 14:45
by jacarlsen
Some 8 years ago we had an operational and test pilot visit us at Kjeller Depot. He showed pictures/video and talked about the bombing carried out in Libya 2011. After the presentation I asked him how this would have gone if Norway had used the F-35. The answer was that now they had flown fuel and loaded F-16's from Crete, tanked on route, bombed, tanked on return and landed Crete. With the F-35 they would have done the same without refueling to and from the target.

Re: F-35 internal fuel, range

Unread postPosted: 24 Jul 2019, 03:37
by johnwill
wrightwing wrote:
vilters wrote:Station: Place where trains depart and arrive
On the station: Is a roof.
So he can sit "on the roof" for 2.5 hrs. :devil:

He never said how far the "station" was form his base, so his 2.5 hrs statement is meaningless info. :bang:
As was my joke above. :devil:

Well, an F-16 with less fuel and a higher DI has a >2hr station time, at 750km. If we use some deductive reasoning, we can conclude that an F-35A will likely have 2.5hrs on station at >750km.


DI from different airplanes cannot be compared. A store with the same incremental drag effect on two different airplanes will have different DI because DI is incremental drag coefficient, which includes reference wing area. Same drag, different wing area, different drag coefficient, different DI.

Re: F-35 internal fuel, range

Unread postPosted: 24 Jul 2019, 04:28
by spazsinbad
mixelflick wrote:Someone once relayed an anecdote as to gas, range and the gun. Loosely, they asked F-35B/C drivers which they'd prefer: More gas, or a gun? They almost universally wanted more gas. To me, that speaks volumes. I guess I would too, flying over the ocean with my airfield always moving!

BUT that is the best part - so good to get home to mother. IF that is done at maximum arrested landing weight of fuel it is even better. In case anyone not aware the carrier is called 'mother' in navy brevity code. Is it called that today? Not sure - I'll check. "Mother - Parent ship" https://en.wikipedia.org/wiki/Multiserv ... ity_code#M

Everyone would LIKE to be back at mother with max gas at CHARLIE TIME. <burp> :devil: "CHARLIE. 1. Land aircraft on ship. 2. The expected landing time on a ship." http://nato.radioscanner.ru/files/artic ... app7e_.pdf (0.25Mb)

Re: F-35 internal fuel, range

Unread postPosted: 24 Jul 2019, 04:48
by weasel1962
Assume 1500nm range. 300+kts cruise speed yields close to 5 hours. Take 1+hr to get to 750km and another 1+ back. 2.5 hours on loiter before tanking should be achievable.

Re: F-35 internal fuel, range

Unread postPosted: 24 Jul 2019, 14:02
by doge
I dug the Range further. 8)
It seems to have been said for three years ago. :doh: (From RIAT16)
https://twitter.com/RAeSTimR/status/751039626232598528
Tim Robinson@RAeSTimR
Editor in Chief of AEROSPACE - the flagship magazine of the Royal Aeronautical Society.
7 Jul 2016
Range of F-35 compared to F-16 is some "30-70% better, depending on mission" says Norwegian MoD spokesman. #RIAT16

Re: F-35 internal fuel, range

Unread postPosted: 24 Jul 2019, 16:10
by ricnunes
doge wrote:That's over 30% of F-16's range...
How long is the range of the F-16? 8) :devil:
The F-35 has the ability to carry weapons and fuel internally. This contributes to the aircraft getting considerably better range than previous aircraft due to less air resistance. In relation to today's Norwegian F-16, we estimate that the F-35 will have a full 30% more range with corresponding weapons load.


By reading Hanche's words, my deduction is that the F-16 (in that case) would absolutely and at least carry two (2) BIG external fuel tanks under the wings (and perhaps even a 3rd fuselage external fuel tank).

Re: F-35 internal fuel, range

Unread postPosted: 26 Jul 2019, 06:08
by weasel1962
Do the Norwegian F-16s operate with 600 gal tanks? If so, the 30% increase is more impressive.

Otherwise internal fuel + 2 x 370 gal + centerline 300 gal tank = ~13500 lbs fuel carried for an F-16A. It would be roughly logical that an F-35 that carries 18,000 lbs of fuel would have ~33% more range when it carries 33% more fuel. If 600gal tanks then that adds 3000lbs.

Re: F-35 internal fuel, range

Unread postPosted: 26 Jul 2019, 06:54
by spazsinbad
"... If 600gal tanks then that adds 3000lbs." 600 US gallons jet fuel weighs approx. 4,000 pounds https://jscalc.io/embed/oyHJrYooUr1wDQPb

An A4G carried either 150 gallon tanks (1,000 lbs) or 300 gallon drop tanks (2,000 lbs of fuel) plus weight of drop tanks.

Re: F-35 internal fuel, range

Unread postPosted: 26 Jul 2019, 08:05
by XanderCrews
blain wrote:You can either carry a lift fan or you can carry 6,000 lbs more fuel and have a larger weapons bay. I seem to remember the Marines doing alright with F-4s in Vietnam and fighting two major wars in the Middle East with Hornets and Intruders. Wars in which they really didn't STOVL.

Now the focus is China. Some people say it might be good to have fighters with range. The Marines say the F-35Bs gives them the option of operating close to the enemy or behind enemy lines from expeditionary bases. It's not World War II when you are both fighting far from home on islands in the South Pacific where the geography and strategy favors seizing islands and establishing bases. If you want to seize and operate from expeditionary airbases you will likely be doing that in the enemy's back yard. TBH - I'd rather punch and jab from close from the end of the opponent's reach than get close to his face and try to slug it out.

Saddam's military might not notice you have an EAB on his territory, but I wouldn't try that against the Chinese when you likely won't need to. If range in fighters is important then the Marines need an adequate mix of fighters with that element. Three squadrons are not enough. If the Marines split the buy they would end up with 210 Bs and 210 Cs.


Image



As usual with this subject you make false assertions based on your presumption and then "debunk" them when they were never true in the first place. If you're interested in details I can lay them out line by line. One of the things I really enjoy about you Blain is in a scenario where a Marine is rescuing a kid from a burning building, an airman is beating his wife, and a sailor is passed out on the lawn, you'd criticize the Marine for not carrying the kid how you think he should.

I'll bottom line this really fast. The USMC, is begrudgingly a part of the US Navy. and like the Navy we put a premium on expeditionary warfare and projecting power from the sea and a half dozen handy other phrases that are used to explain why we matter and how our capabilities are unique and can't be replicated by the alternatives. Anywho, Its just our little way of saying "we hear you whining, and we don't care, thanks anyway."

Re: F-35 internal fuel, range

Unread postPosted: 26 Jul 2019, 08:13
by XanderCrews
Hmmm. At some point range and payload is going to matter for the Marines, especially in the Pacific. There is only so many big deck amphibs you will be able to operate off from and defensible islands. I'm surprised there is no one in the Marines advocating for a 50/50 mix of Bs and Cs.


Im surprised at your surprise. the Marines prefer STOVL because it fits their operational model and based on their actual combat experience, and not what you think (take a bite of that humble pie) they should do. this is whats called a "trade off" wherein one option is preferred at the expense of something else.

If I proposed B-52s for the Navy in lieu of CVNs, or that they should go with a 50/50 mix of CVW/B-52 since B-52s have a larger bay and more range, How much time would you spend explaining why this cannot happen? Would not your time be spent better doing other things? And if you devise a concise explanation, why would you assume he would understand?

The Marines rejected the f-14 in preference for those Hornets, despite the F-18 numbers not being as rosy as some Tomcat numbers, a decision that has been "justified" to say the least. maybe they've earned the benefit of the doubt?

crosshairs wrote:
sprstdlyscottsmn wrote:Legacy Hornet drivers are going to be impressed with the F-35B. F/A-18C only has 10,800 internal. The 13,300 on the F-35B is like a Hornet with a centerline.

The F-35C is like an F-14 with drop tanks.


Minus the speed, acceleration, altitude, maneuverability, or numbers of aams.


you think F-35C can't top 8 AAMS?

Swing and Miss, we already Tomcat guys who have flown F-35C and I got to hear from a test pilot how the F-35C is more maneuverable (and of course much easier to fly, so a nugget won't spend 3 years try to learn how to extract performance from it. A lot of this stuff your'e going to have to take to extremes before the F-14 has advantage, and those extremes are all dangerous for Tomcats and only for test pilots in almost all cases.)

I'm a Tomcat fan, but at one point we have to let the bird designed 50 years ago rest in peace.

Re: F-35 internal fuel, range

Unread postPosted: 26 Jul 2019, 08:45
by weasel1962
spazsinbad wrote:"... If 600gal tanks then that adds 3000lbs." 600 US gallons jet fuel weighs approx. 4,000 pounds https://jscalc.io/embed/oyHJrYooUr1wDQPb

An A4G carried either 150 gallon tanks (1,000 lbs) or 300 gallon drop tanks (2,000 lbs of fuel) plus weight of drop tanks.


The calculations are as follows:

370 gal = 370 * 6.5 = 2405 lbs
600 gal = 600 * 6.5 = 3900 lbs

hence the difference of one tank is 1495 lbs (3900-2405) rounded up to 1500 lbs.

The difference of 2 tank will yield 2 * 1500 lbs = 3000 lbs more fuel.

Hence carrying 2 * 600 gal tanks over 2 * 370 gal tanks will yield 3000 more lbs of fuel.

Having a 70% or more increase in range of the F-35A vs F-16 can easily be achieved by simply comparing the F-35A to a F-16 without any EFTs or one centerline tank. If the F-35A carrying 18k lbs of fuel can achieve 70% more range vs an F-16 carrying 16500 lbs of fuel, I'd say that's impressive.

Re: F-35 internal fuel, range

Unread postPosted: 26 Jul 2019, 08:59
by spazsinbad
'XanderCrews' said: "...[USMC] we hear you whining, and we don't care, thanks anyway."" This had me laughing out loud. I want more grins please. A cursory glance at the acronyms for expeditionary warfare by USMC should put people right eh.

OMG there is a tonne of this stuff on appropriate threads here: viewtopic.php?f=61&t=54445 onesuch

Basic instincts: Resetting USMC core operational mindset

viewtopic.php?f=61&t=52650 F-35B USMC 2017 "not going to stay the same" 2such

Then a series of yearly USMC Aviation Plan PDF threads with muchos commentos added.

Re: F-35 internal fuel, range

Unread postPosted: 26 Jul 2019, 13:45
by pron
weasel1962 wrote:Do the Norwegian F-16s operate with 600 gal tanks? If so, the 30% increase is more impressive.

Otherwise internal fuel + 2 x 370 gal + centerline 300 gal tank = ~13500 lbs fuel carried for an F-16A. It would be roughly logical that an F-35 that carries 18,000 lbs of fuel would have ~33% more range when it carries 33% more fuel. If 600gal tanks then that adds 3000lbs.

You can see the Norwegian F-16 on Souda Bay here, and maybe you see how big the tanks are?

https://www.nrk.no/nordland/f-16-pa-den ... -1-7563573

Re: F-35 internal fuel, range

Unread postPosted: 26 Jul 2019, 17:32
by sprstdlyscottsmn
looks like the 370s.

Re: F-35 internal fuel, range

Unread postPosted: 26 Jul 2019, 20:44
by quicksilver
Back to the TOS question...

While the ‘C’ is a significant addition to the CVW, bar napkin math suggests we should temper our enthusiasm wrt 2.5hrs at ~500nm. If one subtracts fuel on the front end for start, taxi, t/o and climb to altitude, as well as fuel reserves for recovery and on-deck mins, we’re probably talking about 15K#-ish of JP for max range transit to/from and max endur on-station time.

Still very, very impressive number(s) but probably not 2.5@500.

Re: F-35 internal fuel, range

Unread postPosted: 27 Jul 2019, 01:29
by weasel1962
CAP not ideal to be too far from the CVBG. Need to be able to vector to any direction.

Logically, it makes sense to be ~50nm-100nm away max. If the inbound aggressor is in the same direction, its still able to intercept at 500nm going outbound. If the aggressor comes in from the opposite direction, then CAP u-turns to tackle in the opposing direction.

Even if C can do 2.5 hrs TOS, it wont cos CAP won't wait to bingo fuel otherwise there's no ability to intercept. That's where buddy refuel and in near future the huge, huge benefit of MQ-25 comes in. They're going to keep CAP fully fueled and ready to go.

Re: F-35 internal fuel, range

Unread postPosted: 27 Jul 2019, 22:16
by doge
I should have previously posted a range article with the same content at F-16.net, but this newly discovered another article had some new contents added. ; About Link 16 and MADL.
https://www.monch.com/mpg/news/air/4370 ... waffe.html
SENSOR FUSION - THE F-35'S SECRET SAUCE
Details Published: 18 October 2018
As the German Air Force (Luftwaffe) is looking for a replacement for its TORNADO combat aircraft, MONCh had the opportunity to visit the Lockheed Martin Aeronautics factory in Fort Worth, Texas/USA to discover at first-hand what the pros and cons are for the fifth-generation fighter as a candidate. Refreshingly open and transparent in response to some very searching questions, company officials provided some surprising – and thought provoking – information.

“In contemporary integrated air defence environments, it is almost impossible for fourth generation aircraft to prosecute their missions and survive,” Director of F-35 International Business Development, Steve Over, told MONCh.

In a current generation aircraft over 90% of the radar cross-section is a result of the external weapons load and LINK 16. In the case of the F-35, the internal weapons bay removes that issue almost entirely, reducing the radar return to a hostile air defence system and contributing to the aircraft’s very low observable (VLO) characteristics.

Similarly, an F-35 with its internal fuel load of 18,000lbs will have a broadly similar range to an F-16 ‘maxed-out’ with every auxiliary fuel tank it can carry – enhancing mission execution and survivability.

Further adding to stealth, instead of using the LINK 16 datalink, the aircraft's Multifunction Advanced Data Link (MADL) allows for stealthy communication that has a low probability of detection. To complete missions in denied airspace, pilots need a way to share information securely, without revealing their location to enemy forces. The F-35 has incorporated Northrop Grumman’s MADL into its missions systems to provide pilots with the ability to connect with other planes and automatically share situational awareness data between fighter aircraft. The MADL is a high-data-rate, directional communications link that allows for the secure transmission of coordinated tactics and engagement for 5th Generation aircraft operating in high-threat environments. The MADL is one of 27 different waveforms in the F-35’s communication, navigation and identification (CNI) suite.

The aircraft's sensor fusion engine then takes the collected data and combines it into a holistic picture that is fed to the pilot.

Would it therefore not it be sensible to add the F-35, with its sensor fusion capability and the promise of stealth, to the Luftwaffe’s force mix? Admittedly, there are significant political considerations that need to be taken into account when thinking about the commitment to the TYPHOON joint programme: but economics, security of supply and sovereign capability are all issues that can be resolved, not impenetrable obstacles to making an enlightened decision.

Re: F-35 internal fuel, range

Unread postPosted: 28 Jul 2019, 23:23
by spazsinbad
Pardon me if this same info has been posted in THIS thread - it has been posted several times in sub-forums so here goes:
Graphic was first posted by 'SWP' here viewtopic.php?f=58&t=12237&p=245913&hilit=WMcCoy#p245913 but it has a 'photobucket' logo on it now so I'll attach another PDF page grab. My original PDF was downloaded from here but no longer available: (probably available new URL) http://www.dtic.mil/ndia/2012targets/WMcCoy.pdf (3.8Mb)

I see a version of it here for download: http://www.f-16.net/f-16_forum_download-id-17154.html (PDF 3.7Mb)

F-35B & C 'range' pages: http://www.aereo.jor.br/wp-content/uplo ... tation.pdf (4.4Mb)

'doge' earlier for F-35C range: viewtopic.php?f=22&t=28906&p=314291&hilit=Presentation+range+nautical#p314291

NEXT PAGE of the PDF for the F-35B range.

Re: F-35 internal fuel, range

Unread postPosted: 29 Jul 2019, 13:07
by quicksilver
weasel1962 wrote:CAP not ideal to be too far from the CVBG. Need to be able to vector to any direction.

Logically, it makes sense to be ~50nm-100nm away max. If the inbound aggressor is in the same direction, its still able to intercept at 500nm going outbound. If the aggressor comes in from the opposite direction, then CAP u-turns to tackle in the opposing direction.

Even if C can do 2.5 hrs TOS, it wont cos CAP won't wait to bingo fuel otherwise there's no ability to intercept. That's where buddy refuel and in near future the huge, huge benefit of MQ-25 comes in. They're going to keep CAP fully fueled and ready to go.


I wasn’t speaking to CAP considerations, only to the idea (expressed earlier in the thread by yourself and wrightwing) that the jet is capable of ~2.5hrs on station at ~500 miles distant from its launch point — wherever that launch point might be. To wit (and I quote) —

WW — “If we use some deductive reasoning, we can conclude that an F-35A will likely have 2.5hrs on station at >750km.”

1962 — “Assume 1500nm range. 300+kts cruise speed yields close to 5 hours. Take 1+hr to get to 750km and another 1+ back. 2.5 hours on loiter before tanking should be achievable.”

IMNSHO, that notion is demonstrably...generous. But let’s be a little more precise with our numbers. (Bar tender...new napkin please). 750 kilometers is actually very close to 400 nautical miles. That’s about an hour (.8hrs) out and an hour back from a given launch point. We have a general idea how much JP the jet will burn at max range cruise and max endurance Mach numbers at assumed optimum cruise altitudes at or above 30K’. What the discussion didn’t consider is how much fuel it takes
for start, taxi, takeoff and climb to altitude and for recovery, landing and reserves; I’ll be generous and call the front end of that 2K#. Someone else here said fuel reserves are 2.5K; we didn’t get to parse that but let’s use it anyway. That means that from the 19.5ishK# of JP we have at startup, I’m gonna subtract 4.5K# to get to what I have for transit to/from and on-station time. Simple math tells me that’s ~15K#.

So, let’s say 4K (5K/hr times .8hrs) out, and 4K back, and we now have ~7K# to work with on station. Even here at the f-16.net watering hole, I can’t divide 7 by 4.5 (assumed max end fuel burn) and get 2.5. But that’s just my math...

Re: F-35 internal fuel, range

Unread postPosted: 29 Jul 2019, 15:39
by sprstdlyscottsmn
The last simulation I ran on the F-35C for CAP, which included the reserves, ground time, opt cruise, etc came out to just two hours at 400nm. 2.5 hours was achievable at 300nm, That was with my older model, but it involved slightly less napkin-y speed for climbout, transit, and RTB.

Re: F-35 internal fuel, range

Unread postPosted: 30 Jul 2019, 07:13
by weasel1962
Using the attached as a basis.

19,750 lbs internal fuel for C, less 5000 lbs for take off, climb, landing approach and fuel reserve yields 14,750 lbs for mission. At 11.31 lbs per nm, that 14750 lbs translates into roughly 1304 nm. Assuming cruise speed at 320kts, that translates to 4 hours endurance which means 1 hr (320nm) there, 2 hours on station and 1 hr back. Climb and reserve would easily make up the 80nm difference and 30 mins extra (maybe more) if really required. Napkin numbers of course. I suspect loiter speed could stretch endurance but as mentioned, don't think stretching to bingo is a standard procedure.

Re: F-35 internal fuel, range

Unread postPosted: 30 Jul 2019, 15:32
by sprstdlyscottsmn
weasel1962 wrote:Assuming cruise speed at 320kts,

That assumption is not valid. 320kt TAS is way too slow for tactical aircraft max range cruise. 320 is closer to the IAS.

Alt 30,000ft
320KTAS-----494KTAS
200KCAS-----320KCAS
0.543M-------0.838M

Alt 36,000ft
320KTAS-----541KTAS
180KCAS-----320KCAS
0.558M-------0.943M

Alt 40,000ft
320KTAS-----585KTAS
164KCAS-----320KCAS
0.558M-------1.020M

Also, you are using an F-35B chart to infer information about the F-35C. Their climb/cruise/descent profiles will be vastly different due to the wing. Even so, the 1,304nm you are assuming for cruise would be closer to 2.4hr endurance using 320KCAS at 36,000ft.

Best LOITER was given as 32,000ft, 0.75M (438KTAS, 271KCAS), with about 4,600pph in the F-35A with this stated to give a total of 4 hours of fuel. Obviously you don't get to use all 18,400lb of fuel in loiter but as you get lighter you burn less fuel and go up in altitude.

Re: F-35 internal fuel, range

Unread postPosted: 30 Jul 2019, 15:48
by element1loop
sprstdlyscottsmn wrote:Best LOITER was given as 32,000ft, 0.75M (438KTAS, 271KCAS), with about 4,600pph in the F-35A with this stated to give a total of 4 hours of fuel. Obviously you don't get to use all 18,400lb of fuel in loiter but as you get lighter you burn less fuel and go up in altitude.


438 KTAS loiter is not that far away from getting-out-of-Dodge speed for the legacy jets.

Re: F-35 internal fuel, range

Unread postPosted: 30 Jul 2019, 16:21
by outlaw162
438 KTAS loiter is not that far away from getting-out-of-Dodge speed for the legacy jets.


271 KCAS won't get legacy or any generation jet 'out of Dodge' quickly, let alone Kansas.

edit: legacy 'get out of Dodge' speeds were roughly anywhere from 550-750 KCAS depending on type

Re: F-35 internal fuel, range

Unread postPosted: 31 Jul 2019, 02:44
by spazsinbad
OOoohh youse guys are hilarious. I'd reckon 'QS' has a good handle on it all. And it is goodnight from him - with ONE stent.

Re: F-35 internal fuel, range

Unread postPosted: 31 Jul 2019, 13:41
by element1loop
spazsinbad wrote:OOoohh youse guys are hilarious. I'd reckon 'QS' has a good handle on it all. And it is goodnight from him - with ONE stent.


438 KTAS @ 32kft = Mach 0.75

Re: F-35 internal fuel, range

Unread postPosted: 01 Aug 2019, 01:38
by weasel1962
sprstdlyscottsmn wrote:320kt TAS is way too slow for tactical aircraft max range cruise. 320 is closer to the IAS.

Alt 30,000ft
320KTAS-----494KTAS
200KCAS-----320KCAS
0.543M-------0.838M

Alt 36,000ft
320KTAS-----541KTAS
180KCAS-----320KCAS
0.558M-------0.943M

Alt 40,000ft
320KTAS-----585KTAS
164KCAS-----320KCAS
0.558M-------1.020M

Best LOITER was given as 32,000ft, 0.75M (438KTAS, 271KCAS), with about 4,600pph in the F-35A with this stated to give a total of 4 hours of fuel. Obviously you don't get to use all 18,400lb of fuel in loiter but as you get lighter you burn less fuel and go up in altitude.


Absolutely agreed. The question is whether its theoretically possible for the C to have 2.5 hrs (or close to) TOS. Of course it can with the assumptions of higher altitudes with a very low loiter speed for max end. The assumption of 320 kts is of course valid for the question. As already mentioned, its not going to happen in actual ops but that's not the question here.

sprstdlyscottsmn wrote:Also, you are using an F-35B chart to infer information about the F-35C. Their climb/cruise/descent profiles will be vastly different due to the wing. Even so, the 1,304nm you are assuming for cruise would be closer to 2.4hr endurance using 320KCAS at 36,000ft.


No other publicly available chart available. All 3 variants are using the same engine so fuel use rates should roughly be about the same. Agreed wing affects climb and descent rates but difference on range won't be materially far off.

What I like about the chart is it explains the fuel burn rate is based on a training profile for a sortie (minus actual ops). So theoretical max endurance fuel burn rates will probably be a slightly lower consumption figure.

Re: F-35 internal fuel, range

Unread postPosted: 01 Aug 2019, 01:49
by Corsair1963
Anyway you look at it the F-35 has exceptional range for a Tactical Fighter. This will only improve with time. As they're developing even more fuel efficient engines. Including newer models of the F135 plus the ACE Engines. (XA100 and XA101)



Plus, external Fuel Tanks and CFT's.

Re: F-35 internal fuel, range

Unread postPosted: 01 Aug 2019, 03:45
by marauder2048
I tend to think CAP distances will grow beyond the outer defense zone mean of 200 nm
and more towards 300+ nm by virtue of the fact that the escort AAW weapons are no
longer horizon limited and are much, much longer ranged e.g. SM-6 Block IB.

Re: F-35 internal fuel, range

Unread postPosted: 01 Aug 2019, 23:04
by quicksilver
“The question is whether its theoretically possible for the C to have 2.5 hrs (or close to) TOS. Of course it can with the assumptions of higher altitudes with a very low loiter speed for max end.”

Actually, the question was 2.5hrs at what distance from the launch point. We have to assume a TAS icw the #/nm number; assuming 8.5nm/minute (510KTAS) that’s ~96#/min or -5700#/hr. That’s 11.4K# just from to/from ~500nm, leaving 3.3K to burn on station.

If we go to 400nm, we get another ~2K to burn on station, or 5.5K total (1.2hrs).

If we go to 300nm, we get a total of roughly 8K to burn on station (or 1.7hrs).

Re: F-35 internal fuel, range

Unread postPosted: 10 Aug 2019, 09:58
by doge
Greg Ulmer says the F-35 has the best Range of the 4th or 5th gen fighters. 8) Best...!! :shock: (Get bigger and bigger...! :doh: )
Greg Ulmer, vice president and general manager of the F-35 Ligthning II fighter program at Lockheed Martin.
From RIAT 2019 @1:00~
A lot of people talk about the range and payload for the airplane.
The airplane performs exceedingly well in terms of range.
Probably, it has some of the best range in terms of even 4th or 5th gen aircraft.