F-35 internal fuel, range

Discuss the F-35 Lightning II
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Corsair1963

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Unread post05 Feb 2020, 07:05

eagle3000 wrote:
mozza wrote:Rafale has 2 sort of EFT the 2000L ones and the supersonics ones (1250L) he can fly with CFT too but no one ordered it (1150L).


True. Note: even though the fat 2000 l tanks are called subsonic tanks, they're good for Mach 1.4.



Yeah, and how long could they fly at Mach 1.4 in that configuration???
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hornetfinn

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Unread post05 Feb 2020, 09:56

I think it's pretty clear that in any realistic air-to-ground configuration is superior to pretty much all other fighter jets.

Best case for F-35 is the 2x2,000lb weapons or 8xSDB/Spear 3, targeting pod and 2 BVR missile. Here F-35 has very long range, very high performance which most 4th gen fighters would struggle to compete with even in air-to-air loadout and without factoring in the massive SA advantage F-35 has. In similar loadout I think all 4th gen fighters are pretty much subsonic and have restricted AoA and available Gs. According to this: https://www.flightglobal.com/flight-tes ... 47.article

The DFCS is a "g" demand system with +9.0g/29° angle of attack (AoA) limit in air-to-air mode and +5.5g/20° AoA limit in both of the two air-to-ground/heavy stores modes (ST1 and ST2) to cater for forward or aft centre of gravity. The aircraft continuously "recognises" the load it carries, but indicates and leaves the final DFCS mode selection to the pilot. Minus g limit in all modes is -3.2.


I bet all 4th gen fighters have this kind of limitations when loaded for air-to-ground. When they are +5-6Gs and 20° AoA limited, F-35 can do 7-9Gs and 50° AoA and go to Mach 1.6. That is massive difference there when it comes to survivability for example.

When carrying heavy air-to-ground load all 4th gen fighters maybe save F-15E and Su-30MKI have to choose between range and payload due to having to carry big and heavy EFTs. F-35 carries 3 large EFT worth of fuel internally while being able to carry a lot of heavy weapons. It can carry about 3 times as many heavy weapons as most 4th gen fighters in realistic air-to-ground loadouts (bombs/missiles, 3 EFTs and targeting pod at least).

In pure air-to-air configurations 4th gen fighters are a lot more competitive when it comes to range, performance and maneuverability. Of course they are not competitive when it comes to stealth and SA. But even then there are not many fighters which can do 9Gs, 50° AoA and have similar acceleration to F-35 while having mission radius of 750+ nm. Of course with EFTs punched out, some fighters have about equal performance and maneuverability. I can think of only Su-35 which can possibly do all that equally well. SH has quite large thrust disadvantage.
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hornetfinn

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Unread post05 Feb 2020, 11:09

marsavian wrote:Exactly Spurts. I didn't think I was saying anything too controversial using LM's own numbers even though it goes against widely held popular belief. F-35 have similar thrust/weight when fully loaded in fuel for Air to Air as well as actual values in the same ballpark. I assumed similar lift and subsonic fuel consumption so the only real unknown that would affect range/fuel would be the drag of the clean F-35 vs the drag of Typhoon with 3 EFTs, both being their fully loaded fuel configuration, and LM say that Typhoon in this EFT configuration can match the clean F-35 range with slightly less fuel which is telling me that their drag in these configurations are similar. Further validation can be derived from the fact that Typhoon with 3 EFT can hit Mach 1.8 which again is in clean F-35 ballpark numbers.


You have to remember that F-35A range is with 5 percent fuel degradation and a 2 percent reduction in thrust. So the stated range for F-35A should be quite easily exceeded in real life. I don't know how much this will affect range, but I bet it's something like 10 percent or so. Thrust reduction will likely affect range quite a bit more than just 2 percent.

Another thing is that weight affects spesific range per amount of fuel. From F-16 manual it seems that weight difference between F-35 and EF Typhoon with 3 slim EFTs means about 10 percent difference in spesific range per pound of fuel. Of course it also affects takeoff and climb at least as much. What I mean is that F-35 will need more thrust and thus fuel to overcome the heavier weight.

So I think F-35A has somewhat lower drag than EF Typhoon with 3 EFTs, IMO, the max speed is not necessarily a good indicator as air intake design and artificial limits affect the top speed figures. Without EFTs, I think EF Typhoon definitely has lower drag though. It's still definitely a beast even with 3 bags.
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marsavian

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Unread post05 Feb 2020, 12:03

Hornetfinn, 12+% increase in F-35 combat radius would be 850nm+ when the most LM are currently claiming for F-35 in A-A mode is 760nm. Remember also the surplus weight of the 3 EFT shells and their pylons when comparing weights. Also the F-35 has 4-6% more thrust on a more modern higher bypass (0.57 vs 0.4) F-135 engine compared to two EJ200 as well as F-35 having 12% more fuel than Typhoon with 3 EFTs. I still stick to my original statement as Typhoon is matching F-35 radius with less fuel, barely less weight and less efficient less powerful twin engines.
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hornetfinn

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Unread post05 Feb 2020, 12:36

marsavian wrote:Hornetfinn, 12+% increase in F-35 combat radius would be 850nm+ when the most LM are currently claiming for F-35 in A-A mode is 760nm. Remember also the surplus weight of the 3 EFT shells and their pylons when comparing weights. Also the F-35 has 6% more thrust on a more modern higher bypass (0.57 vs 0.4) F-135 engine than two EJ200 as well as F-35 having 12% more fuel than Typhoon with 3 EFTs. I still stick to my original statement as Typhoon is matching F-35 radius with less fuel, barely less weight and less efficient twin engines.


I did remember the surplus weight of 3 EFTs and the pylons. EF Typhoon is still almost 15 percent lighter than F-35. Those slim EFTs don't weigh that much after all. LM has also been very conservative with their published figures regarding F-35. When those range figures were published, they stated F-35A empty weight to be 30,000lb and thrust to be 40,000 lb. We know that it has more thrust than that and is lighter. AFAIK, they still use that 5 percent fuel degradation and 2 percent thrust loss in their figures for F-35 and not for the EF Typhoon or other fighters. That alone has to have fairly significant effect on range.

So I don't think Typhoon is matching F-35A range even with 3 EFTs in real life even in air-to-air loadout. Load both with bombs and targeting pod and it's not even close.
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eagle3000

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Unread post05 Feb 2020, 20:58

optimist wrote:With the 3 tanks 2x 2k bombs and 2 BVR missiles and pods? I assume it will need the largest tanks it can carry, to get near the range. I think it would be subsonic.


No probably not. It just means the "subsonic" tanks are cleared for 1.4 Mach.
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eagle3000

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Unread post05 Feb 2020, 21:05

sprstdlyscottsmn wrote:Is this wrong then?


Yes. Look at the date (1998), it's completely outdated.
Some weapons on that chart are not even in sevice anymore.
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Unread post05 Feb 2020, 22:21

eagle3000 wrote:
sprstdlyscottsmn wrote:Is this wrong then?


Yes. Look at the date (1998), it's completely outdated.
Some weapons on that chart are not even in sevice anymore.

You're right, I didn't even see that. So the 3000L centerline tank is like the old 426 gal drop tanks for the F-35, appeared on old loadout charts but never materialized.
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mozza

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Unread post05 Feb 2020, 23:01

Yeah it's old, at this time maybe they planned a 3000L EFT but i never saw it, the magic AAM is retired since long time too.
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optimist

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Unread post06 Feb 2020, 00:56

eagle3000 wrote:
optimist wrote:With the 3 tanks 2x 2k bombs and 2 BVR missiles and pods? I assume it will need the largest tanks it can carry, to get near the range. I think it would be subsonic.


No probably not. It just means the "subsonic" tanks are cleared for 1.4 Mach.

I think something got lost in the translation. I meant even though that tank is cleared for M1.4. The Rafale may not be able to go supersonic with a 3 tanks and 2x 2k bombs and pods.
It would also probably would need the largest tank to get the range.
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mozza

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Unread post06 Feb 2020, 02:13

I don't know about the 2000L EFT but the Rafale can reach at least M1.7 with 3 supersonic EFT and 2 Mica and he can supercruise with 4 AAM and a belly 1250L EFT.
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Corsair1963

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Unread post06 Feb 2020, 03:32

mozza wrote:I don't know about the 2000L EFT but the Rafale can reach at least M1.7 with 3 supersonic EFT and 2 Mica and he can supercruise with 4 AAM and a belly 1250L EFT.



Reaching that speed is very different than maintaining that speed. Just like in "theory" the F-15 has a Top Speed of Mach 2.5 but never reach those speeds under Real World Conditions.
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marsavian

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Unread post06 Feb 2020, 04:20

Corsair1963 wrote:
mozza wrote:I don't know about the 2000L EFT but the Rafale can reach at least M1.7 with 3 supersonic EFT and 2 Mica and he can supercruise with 4 AAM and a belly 1250L EFT.


Reaching that speed is very different than maintaining that speed. Just like in "theory" the F-15 has a Top Speed of Mach 2.5 but never reach those speeds under Real World Conditions.


We discuss this all the time like you keep saying but you just keep ignoring the answers you don't like ...

viewtopic.php?p=434220#p434220

Mr. Christian Worning (Typhoon test pilot):

I have done above Mach 1.6 for a total of 15 minutes with three tanks on, but that was with heavy manoeuvring in between.
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Corsair1963

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Unread post06 Feb 2020, 05:00

marsavian wrote:
Mr. Christian Worning (Typhoon test pilot):

I have done above Mach 1.6 for a total of 15 minutes with three tanks on, but that was with heavy manoeuvring in between.



Sorry, 15 minutes is pretty short. Plus, that statement is very vague??? What was the armament and how long was the "heavy maneuvering". :roll:

That said, for a 4th Generation Fighter the Typhoon likely has the best Supersonic Performance with external stores. Yet, hardly means it could compete with a clean F-35.

As a matter of fact Billie Flynn has said the "contrary" and he is a former TYPHOON TEST PILOT!
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optimist

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Unread post06 Feb 2020, 05:37

marsavian wrote:
Corsair1963 wrote:
mozza wrote:I don't know about the 2000L EFT but the Rafale can reach at least M1.7 with 3 supersonic EFT and 2 Mica and he can supercruise with 4 AAM and a belly 1250L EFT.


Reaching that speed is very different than maintaining that speed. Just like in "theory" the F-15 has a Top Speed of Mach 2.5 but never reach those speeds under Real World Conditions.


We discuss this all the time like you keep saying but you just keep ignoring the answers you don't like ...

viewtopic.php?p=434220#p434220

Mr. Christian Worning (Typhoon test pilot):

I have done above Mach 1.6 for a total of 15 minutes with three tanks on, but that was with heavy manoeuvring in between.

So he exceeded the cleared speed of M1.4 and is he still allowed to fly? Here in australia he would be benched. Again there is no mention of 2x 2,000. Staying on the same page may not be an option, but let's at least try to stay in the same book.
We are talking about the base f-35 mission range, a ground strike with dogfighting on the way home, with a require amount in reserve..
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