F-35 internal fuel, range

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sprstdlyscottsmn

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Unread post11 Apr 2021, 13:40

steve2267 wrote:
Scaling on thrust again, and neglecting increased thermodynamic and aerodynamic efficiencies, such a fuel burn suggests the F135 burns around 2700lb/hr in RTB cruise. Do you buy that Spurts?

I am seeing ~3200 for max End at low fuel and ~3600 for max Range. The F135 has a large power draw so it always has a high fuel burn. I know someone on the boards a while ago said 75-100ppm were common in cruise and it was still near 50ppm at idle.
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Unread post11 Apr 2021, 15:46

steve2267 wrote:I stand to be corrected. I found this post by Gums a little ways back in this thread:

Gums wrote:...

This new guy looks fantastic, with more gas internal than the law should allow. I would like us to have a F-35 driver tell us the fuel flow at normal cruise and 25,000 to 30,000 feet. The Sluf and Viper were about the same, with Viper maybe a bit better. On RTB we both burned about 1,500 lb/hr at .8M and 30,000 feet. I cannot recall our burn going in, but it was much higher.

...


With only two 'winders and a pair of 370gal tanks, the cross-country F-16A magical loads vehicle woulda been similar to a Viper returning home. Maybe gas burn is higher than 1500lb/hr at first cuz of the extra weight, but this would have put total fuel burn on the order of 7k lb, so another 5k in reserve? So maybe not as tight on gas as I had guessed. Which makes sense -- you'd hate to lose your loads test aircraft because of (or during) a PR demo.

Scaling on thrust again, and neglecting increased thermodynamic and aerodynamic efficiencies, such a fuel burn suggests the F135 burns around 2700lb/hr in RTB cruise. Do you buy that Spurts?

There's a link that's been posted on a number of occasions, that offers some insight on burn rates. Back in 2015, Col. Chris Niemi and Maj. Nash Vickers flew from Eglin, FL to Osh Kosh, WI for the EAA AirVenture show. It was a ~900 mile flight, that took 2hrs 14 minutes, and they used 5,000lbs of fuel.
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steve2267

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Unread post11 Apr 2021, 18:32

wrightwing wrote:Scaling on thrust again, and neglecting increased thermodynamic and aerodynamic efficiencies, such a fuel burn suggests the F135 burns around 2700lb/hr in RTB cruise. Do you buy that Spurts?

There's a link that's been posted on a number of occasions, that offers some insight on burn rates. Back in 2015, Col. Chris Niemi and Maj. Nash Vickers flew from Eglin, FL to Osh Kosh, WI for the EAA AirVenture show. It was a ~900 mile flight, that took 2hrs 14 minutes, and they used 5,000lbs of fuel.[/quote]

I remember that story, but was too lazy to go dig it out. Thanks for posting that again. That works out to about 2,222 lb/hr!

A lot of this could be speed related too, could it not? Do you recall if the story stated a cruise speed? I could buy a leisurely fuel flow rate in the 2200-2700lb/hr region (if those AirVenture numbers are accurate -- they don't jive with Spurts figures) around 0.8M, but if they are flying missions / training for ingress / egress up around 0.9M, drag will be increasing a lot as they approach sonic, so fuel rates could easily be pushed up towards the figures Spurts is showing. Anyone filed a FOI for the dang Dash One yet? :drool:

Eglin to Oshkosh, straight line is 815nm. @ 0.8M flight time is only 1:46. @0.7M, flight time is 2:02, toss in routing / climb/descent / traffic factors and I could buy 2:14 flight time. So maybe those guys were on a much more leisurely cruise up to OSH?
KELG-KOSH@0.7M.PNG

More to the point of the above vignette... KEDW -> KADW is 2.4x the distance from KVPS-KOSH, so it would seem F-35A's could easily fly Edwards to Andrews nonstop, burning 12,100lbs and landing with 6,100lb fuel remaining. It's landing with nearly as much gas as the Viper has internal. :shock:
Take an F-16, stir in A-7, dollop of F-117, gob of F-22, dash of F/A-18, sprinkle with AV-8B, stir well + bake. Whaddya get? F-35.
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Unread post11 Apr 2021, 18:56

steve2267 wrote:

There's a link that's been posted on a number of occasions, that offers some insight on burn rates. Back in 2015, Col. Chris Niemi and Maj. Nash Vickers flew from Eglin, FL to Osh Kosh, WI for the EAA AirVenture show. It was a ~900 mile flight, that took 2hrs 14 minutes, and they used 5,000lbs of fuel.

I remember that story, but was too lazy to go dig it out. Thanks for posting that again. That works out to about 2,222 lb/hr!

A lot of this could be speed related too, could it not? Do you recall if the story stated a cruise speed? I could buy a leisurely fuel flow rate in the 2200-2700lb/hr region (if those AirVenture numbers are accurate -- they don't jive with Spurts figures) around 0.8M, but if they are flying missions / training for ingress / egress up around 0.9M, drag will be increasing a lot as they approach sonic, so fuel rates could easily be pushed up towards the figures Spurts is showing. Anyone filed a FOI for the dang Dash One yet? :drool:

Eglin to Oshkosh, straight line is 815nm. @ 0.8M flight time is only 1:46. @0.7M, flight time is 2:02, toss in routing / climb/descent / traffic factors and I could buy 2:14 flight time. So maybe those guys were on a much more leisurely cruise up to OSH?
KELG-KOSH@0.7M.PNG

More to the point of the above vignette... KEDW -> KADW is 2.4x the distance from KVPS-KOSH, so it would seem F-35A's could easily fly Edwards to Andrews nonstop, burning 12,100lbs and landing with 6,100lb fuel remaining. It's landing with nearly as much gas as the Viper has internal. :shock:


Now obviously as you add weapons, the burn rate will increase, but that shows a good baseline.
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Unread post11 Apr 2021, 19:48

steve2267 wrote:Scaling on thrust again, and neglecting increased thermodynamic and aerodynamic efficiencies, such a fuel burn suggests the F135 burns around 2700lb/hr in RTB cruise. Do you buy that Spurts?


fuel_burn.png


That would be around 4000 lbs according to my qwick mafs...
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Unread post11 Apr 2021, 20:50

Those early block airplanes weighed in at under 22000 lb. with full internal tanks and tip missiles. That was before the "a pound a day" weight growth (due mostly to added avionics) for several years.
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Unread post11 Apr 2021, 23:07

wrightwing wrote:There's a link that's been posted on a number of occasions, that offers some insight on burn rates. Back in 2015, Col. Chris Niemi and Maj. Nash Vickers flew from Eglin, FL to Osh Kosh, WI for the EAA AirVenture show. It was a ~900 mile flight, that took 2hrs 14 minutes, and they used 5,000lbs of fuel.


Actual quote was "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." Doing the maths, taken at face value is ~2,310pph at 415KGS for 0.18nm/lb including takeoff and climbout.

That is greatly at odds with every other fuel flow figure given

(optimal cruise is around 32,000ft and 0.75M where it burns 4,600pph - Col Simms: this is 0.095nm.lb at 435KTAS)

(If a pilot took off with full fuel, 2 amraams and 2 2,000lb bombs and flew 590nm and came back with a 10 minute weapon deployment time they would land with around 7-8,000lb still in the tank - lost name of source: this is 0.1124 to 0.1026nm/lb round trip)

I think 5000pph is more likely given that the 415KGS includes climbout and decent.
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Unread post12 Apr 2021, 05:43

Silly question, would you not operate an F-35 at 45,000 feet rather than 35,000 feet for better range, fuel efficiency, faster ground speed, and lower radar return?

It seems silly to operate a stealth aircraft like a passenger jet which has to stay below 42,000 feet because the passengers aren't wearing oxygen masks.
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Unread post12 Apr 2021, 05:57

I'll guess the F-35 variant NATOPS/Flight Manuals/Dash Ones are all on computer while navigation profiles are worked out via computer & double checked perhaps by computer which probably makes the profile according to conditions such as weather, armament, other requirements when entered into said computer. Probably one then can have several options according to other issues noted in the brief which of course can be changed in flight or before the flight starts along with ATC clearance required if necessary. Must be great instead of thumbing through old telephone book sized NATOPS manuals.
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Unread post12 Apr 2021, 14:02

I very much interpret the .75M optimum cruise Stat as Max End.
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Unread post12 Apr 2021, 14:57

Salute!

Missed the new stuff on the thread, and great to hear from John-boy. Hope all is well with vaccine crapola. All I had was high pulse rate for a coupla weeks.

Well, I would take the word of the pilots that flew outta here to WI before numbers on a power point slide number. OTOH, my feeling is the 35 has more drag than the Viper in similar config. Secondly, I can check but also seems we had best range somewhere about 0.85 to 0.9 M up at 35 - 40K.

The SLUF and Viper burned about the same at 40K, tho Viper was faster, and that equates to better range. But SLUF had more gas internal. The big tanks did not seem to be all that bad, but the MERS/TERS were very noticeable looking at fuel flow. You must remember that combat ingress is usually at a much higher speed than a cross country profile. For us to do the 400 nm out and back to Hanoi we cruised slow then pushed it up to mil about 100 miles out. Still real slow and the F-4 LORAN buddies with us were nervous as hell, heh heh.

My only experience in the Viper at combat profiles w. as low alt and hauling tanks, 6 x MK-82, a ECM pod and some AIM-9/ACMI doofers on the tips. Could hold 540 kt IAS and was burning about 9,000 lb/hour. Once clear of the threat, slowed up but still burned much more than basic A2A configuration.

If I wanted super range missions for the 35 the first few days, I would revert to the "paper tanks" like those we used in WW2. Real flimsy and cheap, and jett the things maybe 150 miles out, depending on threat radar capabilities.

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Unread post13 Apr 2021, 04:21

Thanks, Gums. Spouse and I had both shots of Pfizer with no reaction at all. She is approaching old age though, turned 80 on April Fool Day. Been married going on 59 years now. Best decision I ever made.
All the best!
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Unread post06 May 2021, 18:52

(The topic of Range is active, so I will try to participate. 8) (challenge))

Topic on the previous page.
When I compare the old Flight Manuals of F-15A and F-16A, F-16A certainly has a better range. :shock: wow
F-15A: Ferry Range 2,083 nm (Fuel 22,838 lbs ----- [(3)600 gal tank])
F-16A: Ferry Range 2,126 nm (Fuel 13,732 lbs ----- [(2)370 gal tank + (1)300 gal tank])
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F-15A Flight Manual.jpg
F-16A Flight Manual.jpg
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Unread post06 May 2021, 18:58

From an article I found during the Finland HX Challenge. 8) (I dig up what i left alone). Mix multiple correlated articles. (Language is Finnish. For translation, I tried using a website called ilovetranslation.com.)
http://www.lentoposti.fi/uutiset/f_35a_ ... taymp_rist
Over the sea, fighter tanks were refuelled after about 5000-6000 pounds of fuel had passed. They wanted to keep the tanks as full as possible.

https://tekniikanmaailma.fi/lehti/4b-20 ... 95828a-500
In addition to weather and air control, there are other programmes during longer migration. Fighters are refuelled about a thousand kilometers apart. The aircraft was complemented by a tanker which was refuelled several times.

Similarly, in a similar article also, written that F-35 fuel was refueled every 1,000 km.
https://www.is.fi/kotimaa/art-2000006402509.html

    Fact
    ・Refueling interval is about 1,000 km.
    ・Refueling is done every 5,000-6,000 lbs of fuel is consumed.
    ・Fuel was always kept full.
So...If I calculate based on these numbers, won't the Range of F-35 be 3,000 to 3,700 km ? 8) (Are my calculations correct?) Or is there a possibility more than that? :roll:

In my opinion and thought, I think it's longer. 8)
The reason I think so is because the this F-35 is constantly carrying a sinkers of Fuel 12,500-13,500 lbs in flight. :doh: (It won't decrease any more. Heavy Dead Weight !)
As it consumes more fuel and becomes lighter, its fuel efficiency should improve and its flight range should increase. 8)

Furthermore, I would focus on "[About] 1,000 km". And, For a fuel consumption of 5,000 lbs. Use x3.7(18,500 lbs divided by 5,000 lbs)
    If it is 1,100 km, it will be 4,070 km.
    If it is 1,200 km, it will be 4,440 km. 8)
    If it is 1,300 km, it will be 4,810 km. :twisted:
    If it is 1,400 km, it will be 5,180 km ! :devil: (Hypertrophy of desire.)
...Well, after all, it's totally unknown and hypothetical, so the my conclusion is that "the [Heavy Dead Weight] F-35's Range, where when fuel doesn't go below 12,500 to 13,500 lbs", is at [least] 3,000 to 3,700 km or [more than]. :roll: (Inequality sign: ">" "+")
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