I am not aware of many aircraft were fuel played a structural part of an aircraft. Though the SR-71 did use is fuel as a form of coolant at high speeds. Cooling the extremely hot surface of the Blackbird was structurally important. Maybe thats where the idea about that kind of information came from?
F-35 First Flight Comments...
- Thread starter Kurt Plummer
- Start date
Oh yeah, I am aware of this technique for supersonic aircraft such as the SR-71. But what worries me, and I am not an active flyboy, is that there was so much weight shedding on the F-35 that Lockmart had to leave out portions of heat shielding in the engine bay on the 35, which in turn lead to the fuel being used as a heat sink in the engine bay. I am kicking myself for not bookmarking the interview with the general involved with the F-35, but he said that structural damage can occur to the 35 if there is not enough fuel to act as a heat sink (not just at supersonic speeds, but at subsonic speeds due to the incredible heat generated by the engine). Considering that the Navy version will be landing on minimal fuel loads... and considering that there are the occasional missed landings and go arounds, if this is true, then combined with the already thin skins on the 35, we're buying a flimsy aircraft (it would seem).
I'm not one to beat a dead horse since I can't relocate the article, but this gravely worries me about this aircraft since it's "destined" to be the backbone of the US's air combat aircraft.
It seems like we're (the US) is buying an el'cheapo plane due to the Marines and the Brits requirements. I'm old enough and aware of military aviation enough to remember the fabulous aircraft from the 50's and 60's that never made it into production, and what I see and hear about the F-35 makes me shake my head and wonder what ever happened the US militaries abilities to design fighter planes.
Of course much about the 35 is still "secret" but what I can actually see and determine from what is known about it, it really makes me wonder.
God I hope we really didn't screw the pooch with this plane!!
Grand Danois
Entertainer
I wouldn't worry so much. Considering it is a multinational 276 billion $ project, this is something that surely has been brought to attention and already been de-risked at this stage.
The development is not without oversight and engineers and project management would be aware if there was any problem.
But would be very interesting if you could provide something that corrobate what you say.
The development is not without oversight and engineers and project management would be aware if there was any problem.
But would be very interesting if you could provide something that corrobate what you say.
I've looked for that article that quoted the AF general, but can't re-locate it.
Believe me, if I can find it, I will post it!!
BTW, just because it's a $300 billion US dollar program does not mean that all the bugs have been worked out.
KP was right right about the diminishing orders, I believe. After the Iraq/terror war, I wouldn't be surprised to see the orders shrinking down to 500+ airframes for the AF and hence seeing the price/airframe rise to levels of the F-22.
I am not a huge fan of the F-22, but I'd prefer to see the F-35 cancelled and tooling for the F-22 doubled and the AF building up something like 700 airframes and ordering new F-15 Strike Eagles to replace the F-35 bomber mission. Like Kurt said, the F-35 (w/o stealth) is neither a good fighter nor a good bomber (based on a2g load outs). Sure the F-35 has incredible sensor fusion for the pilots and most likely fantastic hands-free flying abilities, but I've got to wonder how well this plane is going to be in the air-to-air missions considering how heavy it is. I am not even certain if the F-35 can launch its internal aam's at supersonic speeds which I think should be a capability incorporated into every new fighter since the F-22.
Can anyone answer this question (and I am not AF but an engineer/scientist/pilot): What ever happened to Boyd's "energy-fighting" equations with the US aerospace industry? Have they all been forgetten about? It just seems that the F-35 is so heavy (even with its big PW) that its simply not going to be able to be a good fighter in the "knife fight" situations.
Another question that I can't figure out: Why are the export countries so keen on the F-35 export version since it will have less LO, and no supercruise capabilities as does the Typhoon?
My apologies for perhaps asking "dumb" questions, but I am very curious about this whole JSF program (I'm *just* a civilian who works on theoretical stuff by the way).
Well, here is all that I could find. But this is not the original article that I read regarding the F-35's heat loads:
"The cooling issue is important. One of the F-35's biggest selling points is its ability to escape radar and other enemy detection systems. Heat is one of the ways that enemies can track an aircraft. The JSF circulates fuel to cool some of its internal components. But near the end of a mission, fuel runs low. The heat signature can become more apparent and, without a coolant, the components can also wear down more quickly. "It can have an impact on the life of the equipment," Heinz said. By identifying the problem now, designers and engineers can develop alternatives, he said." -- per, David Heinz.
The original article that I read specifically stated that structural components on the airframe could be degraded if the F-35 flies without sufficient fuel to cool critical aiframe components. I know that weight is a huge issue with the F-35 due to the Marines and Brits version of the aircraft, but it seems like bad engineering to rely on fuel to keep the airframe cool enough to not suffer from heat fatigue. Being a pilot myself, I know that there are times when sometimes fuel levels to drop lower than desired. If that's true about what I read, then the F-35 (sometimes) is going to suffer from heat fatigue since you can't always keep the tanks at desired levels -- especially with the carrier birds since they typically land with as little fuel as needed for one or two go arounds if they miss the wires.
Anyways, I am not involved with the F-35 in any way, so this could be pie in the sky talk from someone who may or may not know all the ins and outs of the F-35s heat management systems.
"The cooling issue is important. One of the F-35's biggest selling points is its ability to escape radar and other enemy detection systems. Heat is one of the ways that enemies can track an aircraft. The JSF circulates fuel to cool some of its internal components. But near the end of a mission, fuel runs low. The heat signature can become more apparent and, without a coolant, the components can also wear down more quickly. "It can have an impact on the life of the equipment," Heinz said. By identifying the problem now, designers and engineers can develop alternatives, he said." -- per, David Heinz.
The original article that I read specifically stated that structural components on the airframe could be degraded if the F-35 flies without sufficient fuel to cool critical aiframe components. I know that weight is a huge issue with the F-35 due to the Marines and Brits version of the aircraft, but it seems like bad engineering to rely on fuel to keep the airframe cool enough to not suffer from heat fatigue. Being a pilot myself, I know that there are times when sometimes fuel levels to drop lower than desired. If that's true about what I read, then the F-35 (sometimes) is going to suffer from heat fatigue since you can't always keep the tanks at desired levels -- especially with the carrier birds since they typically land with as little fuel as needed for one or two go arounds if they miss the wires.
Anyways, I am not involved with the F-35 in any way, so this could be pie in the sky talk from someone who may or may not know all the ins and outs of the F-35s heat management systems.
Grand Danois
Entertainer
First of all, I am not especially knowledgeable on this issue either, but I'll sure give my opinion. 
Thank you for the quote. Where is it from?
I can't really be fussed about what he says.
1) At the end of a mission is where signature management is least in demand.
2) Wear and tear under these circumstances would then be an issue at some level in all stealth aircraft, and it apparently isn't.
3) If there are these heat fatigue issues, then it is something that takes flight hours off the airframe - just like air combat and other abuse does.
You're right that all bugs have not been worked out. However, if there was such a critical issue still around at this stage I would be surprised. Mind you, the weight issue on the F-35B was "roughly" handled before the SDD. And it seems to be the major issue around.
Numbers for the partner nations are 710+ alone. I doubt this number will go down much. Then there are the USAF/USN/USMC plus export orders. As the projected development costs for the F-35 is roughly the same as for the F-22, then the F-35 would have to be ordered in something like 250 copies in order to cost the same as an F-22. Not very likely. The JSF will have a 3000++ producton run.
The planes ability as a fighter will be fine. It is said to handle like an F-16. Anyway, what kills the enemy today is BVR and HOBS/HMCS missiles combined with SA, stealth and netcentrics. Boyds knife-fights died with this. And cheap manned Riccioni fighters won't take the fight to an enemy expeditionary style, and survive, not today.
There are no export countries so far. There are partner nations, however. And they're are in it because the F-35 offers a superior fighter with enough stealth (they need it), because of political reasons (allied to the US), and industrial reasons.
Where did you get this no supercruise on the JSF/EF from? And does it need it? Discombobulated...
Thank you for the quote. Where is it from?
I can't really be fussed about what he says.
1) At the end of a mission is where signature management is least in demand.
2) Wear and tear under these circumstances would then be an issue at some level in all stealth aircraft, and it apparently isn't.
3) If there are these heat fatigue issues, then it is something that takes flight hours off the airframe - just like air combat and other abuse does.
You're right that all bugs have not been worked out. However, if there was such a critical issue still around at this stage I would be surprised. Mind you, the weight issue on the F-35B was "roughly" handled before the SDD. And it seems to be the major issue around.
Numbers for the partner nations are 710+ alone. I doubt this number will go down much. Then there are the USAF/USN/USMC plus export orders. As the projected development costs for the F-35 is roughly the same as for the F-22, then the F-35 would have to be ordered in something like 250 copies in order to cost the same as an F-22. Not very likely. The JSF will have a 3000++ producton run.
The planes ability as a fighter will be fine. It is said to handle like an F-16. Anyway, what kills the enemy today is BVR and HOBS/HMCS missiles combined with SA, stealth and netcentrics. Boyds knife-fights died with this. And cheap manned Riccioni fighters won't take the fight to an enemy expeditionary style, and survive, not today.
There are no export countries so far. There are partner nations, however. And they're are in it because the F-35 offers a superior fighter with enough stealth (they need it), because of political reasons (allied to the US), and industrial reasons.
Where did you get this no supercruise on the JSF/EF from? And does it need it? Discombobulated...
Ding Ding... you got it
A
Aussie Digger
Guest
LM is manufacturing this aircraft. (The manufacturer of th F-16 series as well). The F-35A is being designed with an aicraft performance/agility level equal to that of the F-16/F-18 series fighters with an internal fuel load similar to that of an F-15, plus it has an unbelievable sensor fusion capability AND a good level of stealth. Perhaps not equivalent to that of the F-22, but FAR better than anything else available to the partner nations.
The Air force personnel of the RAF, RAAF, Israel, the Netherlands, Canada, Italy, Turkey, Norway and Singapore, (not to mentioned USAF/USN/USMC) are not stupid people. If the JSF did not offer a significant performance advantage over existing teen series fighters and existing Euro designs, these countries WOULD not have signed up for it and invested heavily in the SDD program.
Here is how Lockheed Martin describes the F-35A's performance:
The F-35A for the U.S. Air Force matches or exceeds F-16 performance levels and goes several steps beyond with stealth, increased range on internal fuel, and advanced avionics. Operational effectiveness, supportability, and survivability are greatly enhanced as a result.
F-35A
- Like the F-16, the F-35A has an internal gun and a refueling receptacle on top of the fuselage behind the canopy.
- Unlike the U.S. Air Force F-16, the aircraft is stealthy, enabling first-look, first-shot capability. It also has an internal laser designator and infrared sensors.
- Maneuverability characteristics are similar to those of the F-16, with comparable instantaneous and sustained 'High-G" performance.
- The F-35A's range and payload are greatly improved as well.
- The aircraft meets or exceeds all of the known service guidelines for flight performance.
http://www.lockheedmartin.com/wms/findPage.do?dsp=fec&ci=15144&rsbci=12969&fti=0&ti=0&sc=400
Isn't it common knowledge that the F-35 does not supercruise, where as the Typhoon does? The 35's wing layouts and air intakes don't appear to be designed for cruising around 1.6 mach. Sure I'll buy into that maybe when the 35 isn't stocked up on 18 thousand pounds of fuel that it may be capable of low mach speeds (M1-1.2) w/o afterburner. But as everyone who's flown a combat aircraft knows, "Speed is life." When the 35 is flying into hostile airspace with its 2 2k pounders, its going in subsonic allowing for more time to aquire, track, and fire upon the aircraft. (where as the F-22 has its all out blistering speed and better all around LO to better serve as a tactical strike bomber). To me it just seems that the F-35 was designed for cost rather than performance. I've been around long enough to remember near Mach 3.0 fighters from the 60's.... It just seems like the F-35 is something between an F-117 and a Super_A-7 and not a true fighter. With only a handful of F-22s, its obvious to me a retired AF general (with an impressive flying resume) that I am friends with, that we don't *really* need the F-35 as much as we need more F-22s.Where did you get this no supercruise on the JSF/EF from? And does it need it? Discombobulated...
I just hope this 300 billion dollar gamble pays off and we dont end up wasting billions to have the Pentagon pull a "Comanche" or an "A-12" on the program.
(Which is quite possible depending on how the flight test program proceeds).
A
Aussie Digger
Guest
The Typhoon has demonstrated a "short" period of supersonic flying without the use of an afterburner, but so did the original British "Lightning" back in the day. Typhoon has done this in a clean configuration to the best of my knowledge and has not done it with a representative operational warload, nor on a "sustained" basis.
I find it interesting that a "super cruising" capability is SO important that only 1 operational fighter aircraft in history has been able to demonstrate it on a sustained basis, (the F-22) which is of course made ALSO by Lockheed Martin.
No other aircraft or projected aircraft for any US air arm is slated to possess the capability, yet this is only regarded as being a problem for the F-35 series.
It's likely "opponents" the SU-27/30 series or perhaps Mirage series fighters can't supercruise either, but apparently it's a terrible shortcoming in the F-35...
Grand Danois
Entertainer
I think I have read somewhere that the F-35 actually will have operational supercruise ie reasonably beyond the transonic regime. But that would take someone in the know to evaluate such a statement. Anyhow, IIRC supercruise is not something that has been promised for the F-35, but is an added bonus if it happens. It is not so important that just about every other fighter has it.
Btw, I read your supercruise remark as if neither plane had supercruise. Hence my befuddlement.
As to the F-22 as a strike fighter, well, there are a number of threads on this forum discussing this subject. You may find that it is perhaps not that useful at all.
Cheers
Last edited:
Here's a question that I have not seen any asnwer too, maybe someone else who is more familiar with this can answer: Can the F-35 launch its internal AAMs while @ supersonic speeds? With the little knowledge that I have on weapons bays it does not appear to be able to do so since to the best of my knowledge there are no spoilers in those bays.
Grand Danois
Entertainer
The F-35 is not an air dominance fighter, you know that. Tell me, is it supposed to be able to launch at supersonic speeds?
Btw, the Typhoon can be upgraded with the EJ230 wich should take it safely past transonic with AAM's and CFT's ie useful config.
That does strike me as odd that everyone against the F-35 whines about it not having super-cruise when it is SUPPOSED to be a budget aircraft. Nobody expects the F-16 to be as fast or have the endurance of the F-15 so why all the complaints on the Lightning?
Grand Danois
Entertainer
That is because the F-22 is the über fighter to obsess about, and the F-35 is the evil competition that stole all the money from the 1000 aircraft strong F-22 fleet. Despite 300-400 will probably do for air dominance.
But as the multirole striker, the F-35 will do it more efficiently at less than half the cost. It will have enough stealth, maneuverability etc. than the competition out there, so you tell me what's going on.
I think everyone who supports a 1000 F-22s thinks they can be everywhere at once and carry weapons on pylons and still be invisible.
A few of points on the Typhoon: -
1) At present there is no commitment to develop the EJ230, it remains an option/possibility.
2) EF regard the 4 X AMRAMM/Meteor + 2 X ASRAMM + centre tank as the standard clean configuration.
3) The design goal is for “super-cruise” in the a.m. clean configuration.
4) In this context “super-cruise” means transitioning from sub-sonic to super-sonic speeds without recourse to reheat.
5) The expansion of the Typhoon performance envelope has been carried out on several platforms and has been carried i.a.w. modern spiral development principles. (i.e. push the envelope a little, move onto another area while the data is being check, and again to something else before, pushing again in the original area.). As we have been using the latest telemetry it has been possible to make several incremental steps in an area during a single flight. However, flight trials always precedes slowly one, step at a time.
6) As you imply Grand Danois, quite correctly the transonic region can be problematic and for most aircraft is not a regime of flight where one would wish to dally (with the possible exception of the Buccaneer). The development of the engine and the engine management system, flight control system and weapons integration have been carried out on different platforms and to a degree sometimes we had to wait for so aspects of the spiralling development process to catch-up. (I was mainly involved with the integration of the radar and avionics; and have been off that project for five years, but I do have friends engaged in the continuing program). Each trial flight is planned to the last detail and a set of cards is produced detailing exactly what may be attempted on each flight (if each incremental step in successful), plus a few alternatives if some of the earlier work is inconclusive. The “cards” can also be viewed on the displays in the glass cockpit, but the test pilot always has a card copy for his kneepad. Test team on the ground also have access to the top level cards, but can drill down the tree to much greater levels of detail that allow them to monitor the real-time data to confirm or otherwise advise if the scheduled trial should continue. I expect it will be much the same for the F-35 flight trials starting this week.
After a few glitches, the development of the Typhoon flight control system went well. (Crashes will the Grippen and VF-22), ensured that EF2000 FCS was fully developed before flight.
Fast flights on the EF2000 were not carried out until the EJ200 had been sufficiently evaluated. Fast flights with the EJ200 were not carried out until the FCS on the EF2000 had been sufficiently evaluated (chicken and the egg).
The first attempts at super-sonic flight were preceded by bursts of reheat well below Mach 1 and cut short well before the transonic region. For the first series of super-sonic tests the aircraft was completely clean and reheat was engaged from well below Mach 1 to allow the aircraft to accelerate rapidly and punch through into super-sonic flight.
After the anticipated performance of the aircraft at super-sonic speed had been confirmed, more gradual transitions were attempted; still with reheat: then just using dry thrust.
The process has been repeated many times, with different load-outs. The evolution is to push up the load and take a run at it will reheat and then try with just dry thrust.
I know that using the EF definition of “clean” has been proven with a very short boost during the transition into super-sonic flight, and that this was maintained for “tens of minutes”, using just dry thrust alone.
Early next year I would expect the Typhoon to transition into super-sonic speed without reheat and with the full “clean” load.
Back to the F-35.
With just internal stores I would be very surprised if any of the variants could not punch through Mach 1 on dry power, and super-cruise.
Chris
Grand Danois
Entertainer
Thank you Chris. Enjoyed reading that.
It appears to me that there is still a good way to go before the EF has expanded its envelope to its full potential.
'Tens of minutes' in EF 'clean' config is more than I would have expected there was fuel for. Very impressive.
Btw, That was the reason why I mentioned the CFT's and the EJ230. To have some margin in my argument. To have enough fuel and be able to leave the transonic flow regime entirely for efficient flight.
Cheers
It appears to me that there is still a good way to go before the EF has expanded its envelope to its full potential.
'Tens of minutes' in EF 'clean' config is more than I would have expected there was fuel for. Very impressive.
Btw, That was the reason why I mentioned the CFT's and the EJ230. To have some margin in my argument. To have enough fuel and be able to leave the transonic flow regime entirely for efficient flight.
Cheers