F-35 internal fuel, range

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weasel1962

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Unread post26 Jul 2019, 08:45

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.
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Unread post26 Jul 2019, 08:59

'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.
RAN FAA A4G Skyhawk 1970s: https://www.faaaa.asn.au/spazsinbad-a4g/ AND https://www.youtube.com/channel/UCwqC_s6gcCVvG7NOge3qfAQ/
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Unread post26 Jul 2019, 13:45

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
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sprstdlyscottsmn

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Unread post26 Jul 2019, 17:32

looks like the 370s.
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Unread post26 Jul 2019, 20:44

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.
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weasel1962

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Unread post27 Jul 2019, 01:29

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.
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Unread post27 Jul 2019, 22:16

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.
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Unread post28 Jul 2019, 23:23

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.
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Unread post29 Jul 2019, 13:07

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...
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Unread post29 Jul 2019, 15:39

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.
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weasel1962

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Unread post30 Jul 2019, 07:13

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.
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Unread post30 Jul 2019, 15:32

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.
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Unread post30 Jul 2019, 15:48

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.
Accel + Alt + VLO + DAS + MDF + Radial Distance = LIFE . . . Always choose Stealth
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Unread post30 Jul 2019, 16:21

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
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Unread post31 Jul 2019, 02:44

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.
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