F-35 Multirole Joint Strike Fighter

[colay]

Here is the relevant part from the FY2011 IOT&E report (Nov 2011).

That was my understanding as well i.e. it would not support DAS imagery but only display HUD symbology. Still, the BAE rep was explicit it could support the former.

 

[SpudmanWP]

I have no doubt that the helmet itself is capable of displaying some video in the monocle, but that would require more software changes (to convert from one vid format to another) that the program cannot afford (in either time or money).

 

[PeterCrisp]

There seems to quite a lot of alarmist press right now about the carrier variant not being able to land on carries which I must admit would be quite a bad oversight if true. I'm fairly sure the problem will get fixed and that the designers would let a program get this far with such a fundamental design flaw if it was truly unfixable.
Apparently it's a problem with the arrester gear but surely that's a fairly easy fix in the grand scheme of things?

 

[NICO]

There seems to quite a lot of alarmist press right now about the carrier variant not being able to land on carries which I must admit would be quite a bad oversight if true. I'm fairly sure the problem will get fixed and that the designers would let a program get this far with such a fundamental design flaw if it was truly unfixable.
Apparently it's a problem with the arrester gear but surely that's a fairly easy fix in the grand scheme of things?

My understanding is LMT is redesigning the tail hook (changing the shape) and the hold down damper for possible trials in April 2012. Now, if that resolves the problem more or less, than it will be just a minor blip on the radar for the program.

If F35C still fails then we might have a BIG problem since it would appear then that you would have to move the tail hook which would be a major issue. Let's hope it doesn't come to that, it would be really bad in terms on engineering redesign and super bad PR since you already have headlines of USN and RN buying a fighter that can't land on their carriers, that's not the kind of publicity this program needs.

It would be interesting to know what the other US fighters did when they started their arresting trials, did fighters like F4, F8 or F14 have a lot of problems?

 

[LGB]

Yes other aircraft have had issues with the tail hook including the F-4; however, in terms of the F-35 it's not going to be simple to just move it, if they end of having to do that. It's more than a structural redesign but also involves signature management. One certainly hopes they can adjust it within the existing structure. As you say a potential BIG problem.

My understanding is LMT is redesigning the tail hook (changing the shape) and the hold down damper for possible trials in April 2012. Now, if that resolves the problem more or less, than it will be just a minor blip on the radar for the program.

If F35C still fails then we might have a BIG problem since it would appear then that you would have to move the tail hook which would be a major issue. Let's hope it doesn't come to that, it would be really bad in terms on engineering redesign and super bad PR since you already have headlines of USN and RN buying a fighter that can't land on their carriers, that's not the kind of publicity this program needs.

It would be interesting to know what the other US fighters did when they started their arresting trials, did fighters like F4, F8 or F14 have a lot of problems?

 

[Abraham Gubler]

Yes other aircraft have had issues with the tail hook including the F-4; however, in terms of the F-35 it's not going to be simple to just move it, if they end of having to do that. It's more than a structural redesign but also involves signature management. One certainly hopes they can adjust it within the existing structure. As you say a potential BIG problem.

Nope its a minor problem. The F-35C as tested uses a hook point design from the F/A-18 despite having much smaller seperation between the hook and main gear. Solution 1 is move the hook aft. Solution 2 is redesign the hook point so it can trap a wire that hasn't rebounded from the deck. Solution 2 is much easier and achieves the same aim: trapping wires. Guess which one the F-35 project is following?

 

[LGB]

Certainly if they can get it to trap with a hook redesign it's a minor issue. That's yet to be proven however. There are other issues that can pop up with a short hook relative to the distance from the main landing gear. One of course certainly hopes it's a minor issue.

Nope its a minor problem. The F-35C as tested uses a hook point design from the F/A-18 despite having much smaller seperation between the hook and main gear. Solution 1 is move the hook aft. Solution 2 is redesign the hook point so it can trap a wire that hasn't rebounded from the deck. Solution 2 is much easier and achieves the same aim: trapping wires. Guess which one the F-35 project is following?

 

[Marc 1]

Certainly if they can get it to trap with a hook redesign it's a minor issue. That's yet to be proven however. There are other issues that can pop up with a short hook relative to the distance from the main landing gear. One of course certainly hopes it's a minor issue.

Please elaborate on these other issues.

 

[Abraham Gubler]

Certainly if they can get it to trap with a hook redesign it's a minor issue. That's yet to be proven however.

Well not an F-35C which is kind of obvious otherwise they would not be in this problem.

There are other issues that can pop up with a short hook relative to the distance from the main landing gear.

Like what? It actually has a range of advantages assuming you can trap the wire. Like reduced downwards moment if you air trap and lighter structural weight.

 

[ADMk2]

L-M are aware of the issue. They don't think it's as huge a problem as some "experts" are claiming it is.

Design blamed for F-35C tailhook issues - Navy News | News from Afghanistan & Iraq - Navy Times

“The good news is that it’s fairly straight forward and isolated to the hook itself,” said Tom Burbage, Lockheed program manager for the F-35 program. “It doesn’t have secondary effects going into the rest of the airplane.”

Moreover, the rest of the design of the tailhook system, which include the doors and bay that conceal the device and other ancillary hardware, is sound, Burbage said.

“What we are trying to do is make sure that we got the actual design of the hook is optimized so that it in fact repeatedly picks up the wire as long the airplane puts itself in position to do that,” he said.

A preliminary review has already been completed and was done in conjunction with the Naval Air Systems Command and F-35 Joint Program Office.

Burbage said the hook system is already being modified in accordance with the new test data.

“We’re modifying the hook to accommodate what we found so far in test,” Burbage said. “The new parts, we expect to have them back in the next couple of months.”

Tests with the newly modified tailhook should start at Lakehurst, N.J, in the second quarter of this year, Burbage said.

 

[colay]

.. meanwhile the engineers go quietly about their work finding solutions to the problems.

Lockheed Touts Fix for F-35 Fuel Dump | Gannett Government Media | defensenews.com

Lockheed Touts Fix for F-35 Fuel Dump

By DAVE MAJUMDAR | Comments

Jan. 18, 2012


Lockheed Martin has found a way to fix the F-35 Lightning II’s fuel dump system, eliminating a potential fire hazard, a top company official said

“We expect to have that configuration change back in the test airplane early this year,” said Tom Burbage, Lockheed’s Joint Strike Fighter program manager. “The permanent modification that will go into all the production airplanes will be tested by the second quarter of this year.”

The current test aircraft fleet has an interim solution installed, Burbage said.

 

[Air Force Brat]

Jan. 18, 2012


Lockheed Martin has found a way to fix the F-35 Lightning II’s fuel dump system, eliminating a potential fire hazard, a top company official said

They have also suggested the buffeting has been improved by some changes to the flight control system and may require some beefing up of the verticle stabilisers to resolve, they will know more once they get back into the windtunnel with it.

 

[Haavarla]

From my untrained eyes, i always found those verticals stabz on the F-35 to be tin as in fragile..
Anyways, if 'beefing up' means ticker stabz, does it also means more weight?

 

[ADMk2]

From my untrained eyes, i always found those verticals stabz on the F-35 to be tin as in fragile..
Anyways, if 'beefing up' means ticker stabz, does it also means more weight?

It may do, however they have an aggressive weight management plan, that continually looks at ways of reducing weight on the aircraft. It may be that as one hand giveth, the other takes away...

 

[colay]

It may do, however they have an aggressive weight management plan, that continually looks at ways of reducing weight on the aircraft. It may be that as one hand giveth, the other takes away...

Or they could also look at squeezing more power from the engine. The F135 seems to have a significant potential for increased thrust.

 

[Haavarla]

It may do, however they have an aggressive weight management plan, that continually looks at ways of reducing weight on the aircraft. It may be that as one hand giveth, the other takes away...

I thought the weight reduction managment program was much earlier in the design and development phase, and one might believe that right now the F-35 design was somewhat finelized, bar some minor issues(tail hook etc) lately?

If they will have to enlargen both the tail hook, wheel brakes and the verticals stabz this late in the program, it does not sound like an weight reduction are in work, rather otherway around..
Anyway, lets wait and see how it looks like when it goes IOC.

 

[Haavarla]

Or they could also look at squeezing more power from the engine. The F135 seems to have a significant potential for increased thrust.

As do most multiple other engines, but then again it all comes down to TBO.
No thrust increase, if the wtbo decrease.

To put any given operational jet engine through a deep modernization program has to do with funding on the table or not.

 

[colay]

As do most multiple other engines, but then again it all comes down to TBO.
No thrust increase, if the wtbo decrease.

To put any given operational jet engine through a deep modernization program has to do with funding on the table or not.

I don't think the F135 is going to remain static in its present configuration. It's going to have a long production run and is bound to see improvement in both generated thrust and durability as with previous engine deeigns. It still has a lot of room for growth.

 

[jack412]

My guess is that the f-35 will be like the shornet, they keep offering engine upgrades and the forces say they are fine with what they have, other than the already planned block 6-7 engine improvement
although it wasn't elaborated on, it was said there was a reason the KPP is max speed ~M1.6 and the engine was ~40,000lb installed

 

[Air Force Brat]

My guess is that the f-35 will be like the shornet, they keep offering engine upgrades and the forces say they are fine with what they have, other than the already planned block 6-7 engine improvement
although it wasn't elaborated on, it was said there was a reason the KPP is max speed ~M1.6 and the engine was ~40,000lb installed

Thats quite likely true, when you increase output , you by necessity increase fuel consumption and heat, however if the past is any indicator, weight will increase as will thrust. Some of the stress cracking is likely from previous weight reductions, but from experience, all aircraft crack here and there whether from usage or just poor fitment to begin with, or overstress from rough landings over g etc, etc. Just isolating some of these areas of concern should hasten the solutions or fixs, sometimes these are as simple as avoiding certain power settings or operation in certain configurations and that may be what happens in regards to the buffeting since they stated it could cause premature fatique.:daz