F135 engine package upgrades for F-35

All about the Pratt & Whitney F135 and the (cancelled) General Electric/Rolls-Royce F136
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optimist

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Unread post05 Aug 2022, 07:39

quicksilver wrote:“No that is flown at optimal alt and I think speed on ingress/egress? Id need to look that up. it was changed to F-35b/c specs of optimal and why it was increased to 670. Isn't it also a 5% degraded engine?”

You ‘think…’? You ‘need to look that up…’? ‘Isn’t it also…?’

Why don’t you get back to us w references to answers for your own unanswered questions.

Are you ok?
They were 610nm with specified alt and speed. This was changed to optimal and increased to 669nm. The demonstrated performance in 669nm on an A2G mission. I didn't invent the specs of the mission. Why should I have it committed to memory? I'd have to look up the intricate details, like how many minutes circling the airfield before divert. It doesn't change the fact that this is the current spec. Live with it.

It could be worse, the RAAF specs has it listed as 1093km or 590nm
https://www.airforce.gov.au/technology/ ... ifications
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Unread post05 Aug 2022, 08:58

Another consideration is referenced below. Forecast weather at arrival may also vary the 'minimum return fuel' required.
AIR FORCE INSTRUCTION 11-2F-35A, VOLUME 3
7 JUNE 2012 Flying Operations, F-35A OPERATIONS PROCEDURES

“...3.20. Fuel Requirements. page 22
3.20.1. Joker Fuel. Fuel state above BINGO at which separation/bugout/event termination should begin.

3.20.2. Bingo Fuel. A pre-briefed fuel state that allows the aircraft to return to the base of intended landing or alternate, if required, using preplanned recovery parameters and arriving with normal recovery fuel as listed below.

3.20.3. Normal Recovery Fuel. The fuel on initial or at the final approach fix at the base of intended landing or alternate, if required. Fuel quantity will be as established locally or 2,500 pounds, whichever is higher.

3.20.4. Declare the following when it becomes apparent that an aircraft may land at the intended destination or alternate, if required, with:
-------3.20.4.1. Minimum Fuel. 1,800 pounds or less. This is based on 20 minutes reserve at 10,000 feet MSL flying max endurance airspeed (fulfilling AFI 11-202V3 fuel reserve requirements); and,
-------3.20.4.2. Emergency Fuel. 1,200 pounds or less....”

Source: http://www.bits.de/NRANEU/others/END-Ar ... f-35av3(12).pdf (0.5Mb)
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Unread post05 Aug 2022, 10:21

The generic mission doesn't allow for individual base requirements. That may be taken into account, in mission planning.
Going by that, even with divert, they want the plane landing with a min 2,500lb reserve

It was another dead link. I think this is it from 2012
https://www.bits.de/NRANEU/others/END-A ... 812%29.pdf
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Unread post05 Aug 2022, 12:37

The link works for me - just tried it again now (& earlier) so I'll attach it below. I'm not trying to work out anything. I am attempting to ilustrate some of the factors that affect range calculations and giving references to these factors. OK?

I see what the issue is with my first link - somehow the parentheses interfere with the URL:

http://www.bits.de/NRANEU/others/END-Ar ... f-35av3(12 LIKE SO therefore the link needs to look like this:

http://www.bits.de/NRANEU/others/END-Archive/afi11-2f-35av3(12).pdf It won't work when bold but it is this. Copy & paste it. I don't know why the URL breaks at/before the closing parentheses.
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F-35A SOP 2012 USAF afi11-2f-35av3(12) pp78.pdf
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Unread post05 Aug 2022, 14:34

sprstdlyscottsmn wrote:
optimist wrote:now is 670nm

ehh, that is very conservative. I don't have the quote on me but it's been stated that (paraphrased) "If an F-35 takes off on a strike mission and flies 670nm, spends ten minutes over the target area, and returns to base, the pilot will still have 7,000-8,000lb of fuel on board."

I double checked the quote and I misremembered the range.

"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. "

Something to keep in mind is that the spec is a minimum achieved. A "not less than under these conditions"

Edit - the math on this extrapolates to an average .1026nm/lb for the 7,000lb remaining value, and this would only get better as more fuel is burned. with "Normal Recovery Fuel" of 2500lb listed above that leaves 4,500lb for additional transit. at 0.1026nm/lb that is an extra 231nm each way, or 821nm total.

As for the "they switched to optimum and it went to 669nm" I have never seen anything to suggest that is the case. If you have something then by all means share, because from what I am seeing, and all reports of pilots and FAC/JTAC I am seeing is that it might very well range 669nm, then have forty-five minutes to an hour to play. 821-669=152nm saved each way for 304nm total. That's about half an hour at cruise speeds, plus the "10 minutes" already baked into the previous statement.

"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. "

This is more Max Endurance than Max Range based on the speed involved "According to Col. Rob Simms at the US embassy in Oslo the F-35s optimal cruise is around 32000 feet and 0.75 mach where it burns about 4600 pph. Simplified this gives about 4 hours of fuel or 1600+ nm effective range (3000+ km) on internal fuel -- still with a 2500 pound internal tactical loadout."

Further edit

From Reddit; a USAF GCI (Sandy88) talking with some other guys about working with different jets: https://www.reddit.com/r/hoggit/comment ... ets_super/

fringeaggressor wrote:
It's also substantially draggier than the A/C, mitigating most of the raw effectiveness of that additional fuel in a dash. You can hang bags, but then you're just compounding the problem.
Everybody's got a gas problem in BVR. Only player who doesn't is the Raptor.

Sandy88 wrote:
Lol I wish that last part were true. Bolts are much better by comparison.

Scotty1992 wrote:
What is a Bolt? What aircraft has the best legs in your experience?

Sandy88 wrote:
Bolt is what we've been dubbing the F-35, I know the USAF Weapons School has been rolling with Puma but I'm not sold. Anyway, if you want longevity get you a global hawk or MQ-9 those bad boys can stick around for 24 hours but if your strictly talking air-to-air fast movers the Bolt takes it by a mile. I was blown away by the Bolts loiter times when I first worked with them it really is an amazing jet. I'm pretty sure the -35 will end up being called the Puma my unit just uses Bolt for now.

MOAR EDIT!

Briefing Australian journalists at Lockheed Martin's Fort Worth facility on 2 February, Jerry Mazanowski, senior manager of air systems in the company's strategic studies group, compared the air-to-air performance of the F-35 with that of the Eurofighter, Dassault Rafale, Saab Gripen, Boeing F/A-18 Super Hornet and Sukhoi Su-30MKI. He said that in a typical combat configuration carrying four internally stored AIM-120 Advanced Medium-Range Air-to-Air Missiles (AMRAAMs), the F-35 was marginally faster than the Su-30MKI carrying eight beyond-visual-range (BVR) missiles and no external fuel tanks; and that it was faster than the Eurofighter, Gripen C, Rafale and F/A-18 carrying four BVR and two WVR missiles and a single external fuel tank (two in the Eurofighter's case).

Discussing maximum mission radius, Mazanowski presented an air-to-air mission profile in which all the aircraft took off with a weapon load, remained at high altitude and returned after about a minute of combat. All but the F-35 and Su-30MKI were carrying three external fuel tanks.
Under this scenario, the Rafale had a maximum mission radius of 896 n miles, the F/A-18 816 n miles, the F-35 751 n miles, the Eurofighter 747 n miles, the Su-30MKI 728 n miles and the Gripen 502 n miles.

According to Mazanowski, the JSF joint programme office required the modelling to assume an F- 35 engine at the end of its life with 5 per cent fuel degradation and a 2 per cent reduction in thrust.


Norwegian test pilot comparing F-35 to F-16 in combat config - ""Combat radius" for the F-35 is between 30% and 70% longer than we get with the F-16! "

‘High-g maneuvering is fun, but having high fuel capacity and the ability to carry lots of stores is great too. During the weeks when we were flying BFM we also needed to drop a GBU-12 [laser-guided bomb] on the China Lake weapons range. Back in our F-16 days we’d have had to choose, since there is no way you can BFM with a bomb on your wing, let alone having the fuel to fly both missions in a single sortie. With the F-35, however, this isn’t much of an issue. On one of the sorties, my colleague, Maj Pascal ‘Smiley’ Smaal, decided he would fly BFM and still have enough fuel to go to the range afterwards and drop his weapon. During the debrief, the adversary pilot told us he was confused as to why we went to the range after the fight. When ‘Smiley’ told him that he was carrying an inert GBU-12 the entire time and that he then dropped it afterwards during a test event, the silence on the other end of the line was 'golden’..."
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Unread post05 Aug 2022, 15:25

Thanks for that post, Spurts. Pure gold, IMO.

If 821nm can be achieved with a 2500lb fuel "reserve", then if the Israeli's have achieved a modest, or even small range increase... then Tehran, Fordow, and Natanz could all be within range. Special shapes aside, the limitation would seem to be the lack of a GBU-28 capability, which may not be enough anyway.

With an F135 EPE (EEP?) all these should easily be within range. An ACE upgrade, these destinations should easily be within range of the IAF.

Then there is Finland / Poland into Bear country.

The western Pacific situation improves, but that's still a LOT of water to cross.
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 post05 Aug 2022, 15:55

“Thanks for that post, Spurts. Pure gold, IMO.”

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Unread post05 Aug 2022, 19:56

I haven't peaked into this thread in awhile.
Did we ever do the numbers on if the 30% increase in thrust would allow for supercruise?
They increased range is nice but more kinematics is also a great bonus.
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Unread post05 Aug 2022, 20:35

jessmo112 wrote:Did we ever do the numbers on if the 30% increase in thrust would allow for supercruise?
They increased range is nice but more kinematics is also a great bonus.


Who's "we"?

Where'd you put those CFD results and Wind Tunnel test data? Gonna need a little more than just "30% increase in thrust" statement on engine performance, dontchyathink?

"but more kinematics..." don't you get it yet? We're not in Kansas anymore Toto... 4th gen thinking is going to get you dead.
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 post05 Aug 2022, 22:41

steve2267 wrote:
jessmo112 wrote:Did we ever do the numbers on if the 30% increase in thrust would allow for supercruise?
They increased range is nice but more kinematics is also a great bonus.


Who's "we"?

Where'd you put those CFD results and Wind Tunnel test data? Gonna need a little more than just "30% increase in thrust" statement on engine performance, dontchyathink?

"but more kinematics..." don't you get it yet? We're not in Kansas anymore Toto... 4th gen thinking is going to get you dead.


Your preaching to the choir. In all for 5th gen thinking,
Stealth sensos ect, but Chinese doctrine likely borrows from old soviet doctrine. Old soviet doctrine would use 100 bombers to attack 1 carrier battle group.
In such a scenario where your defending against saturation attacks. Dash, magazine depth, and time on station are just as important as VLO.
You might want to jump the bombers as far away as possible. I actually saw a war game ,( it might have been dcs not sure) where the Chinese allowed all of the scrambled fighters to use up anraams. And then the fighters qued SM-6. After the SM-6s were exhausted the CVN and escorts were hit with land based ballistic missiles. The SCS is going to be about dash persistence and magazine depth.
My point is that being able to go supersonic, and throw a missile farther with no reheat might be important on defense.
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Unread post05 Aug 2022, 22:54

jess, as we’ve recently discussed around here, the simple statement ‘30% increase in thrust’ leaves many questions unanswered that would be necessary (along with other data we don’t have) to estimate whether or not such a desirement (supercruise) would be obtainable. It is unlikely that a blanket improvement in thrust would apply across the entire operating envelope of the jet, and (as steve suggests) we don’t have the aero data necessary to understand the magnitude of improvement that might be attained in a given part of the envelope.

Can we make some assumptions? Sure, spurts has already done so. Perhaps he might answer your question.
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Unread post06 Aug 2022, 01:32

sprstdlyscottsmn wrote:I double checked the quote and I misremembered the range.

"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. "

Something to keep in mind is that the spec is a minimum achieved. A "not less than under these conditions"


I have no reason to question the pilot about the remaining 7-8,000lb of fuel. However the standard mission includes a dog fight with AB, a holding pattern over an airfield for a specified time and a divert to another airfield. As spaz shows, on final approach with 2.500lb remaining. I still have no reason to question the official 669nm, as the standard mission spec for the F-35A. The F-35C gets an extra nm at 670nm
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Unread post06 Aug 2022, 01:43

Mass Flow Rate.

I'm not a motorhead, so I don't know for sure... but to first principles, to increase thrust by 30%, you could either increase the acceleration of the same mass flow rate, mdot, by 30%, or you could increase mdot by 30% with the same acceleration, or some mix therein. Increasing acceleration by 30% suggests a lot more heat, and the F135 is already operating at gas turbine record temps. But increasing mdot by 30%? Can the intakes handle that? We had this discussion briefly once before. F-35 was designed way back in the 90's and early 2000's... was AETP even a wet dream back then? Did the aero gurus @ LM design in a 30% margin for increased mdot? I could see them, maybe, allowing for an increase of about 10%. Engineers seem to like +5% or +10% increments. They're not shooting for the moon, then. P&W reportedly had run the F135 up to some insane thrust level of 52,000lbf, if I recall correctly... (but longevity / durability dropped a lot). So P&W may have been able to give some mdot "margins" to the LM guys as to what the F135 might do in a future growth model (e.g. EEP).

Will the F-35 supercruise with +30% thrust? At face value, sure, I'll say it oughta be able to maintain 1.2 Mach at (increased) mil thrust. But that sure is a swag. But next someone will ask... do you think it could supercruise at M1.3? or M1.4? Or... "how far could it supercruise?" I mean... :bang: :bang: :bang:
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 post06 Aug 2022, 01:46

Sure. The spec I referenced has no dogfight and no loiter accounted for. The statements are not exclusive.
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Unread post06 Aug 2022, 02:29

All the range and whatever stuff is all good however THE ENGINE SUB-FORUM has more: viewtopic.php?f=56&t=57064&p=471247&hilit=Publicly#p471247
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