The F-35 No Holds Barred topic

[SOC]

UCAVs are worth ----all in air to air missions, where the Super Hornet is already weak.

Noooooo...in WVR combat, certainly. But an LO UCAV equipped with a secure, LOS datalink could be a very interesting BVR shooter, taking targeting data from an external source like AEGIS or Hawkeye.

 

[Sundog]

UCAVs are worth ----all in air to air missions, where the Super Hornet is already weak.

Noooooo...in WVR combat, certainly. But an LO UCAV equipped with a secure, LOS datalink could be a very interesting BVR shooter, taking targeting data from an external source like AEGIS or Hawkeye.

My friend and I were thinking the same thing. An unmanned missileer concept. With the expected "loiter" capability of a production X-47, they could be very useful as a stand-off defense platform for a carrier task group.

 

[sferrin]

UCAVs are worth ----all in air to air missions, where the Super Hornet is already weak.

Noooooo...in WVR combat, certainly. But an LO UCAV equipped with a secure, LOS datalink could be a very interesting BVR shooter, taking targeting data from an external source like AEGIS or Hawkeye.

True. In fact that could be a pretty nasty surprise, but it'd still be a niche role for it.

 

[mz]

What about the sudden stall problem at high alpha, have you heard anything about that as mentioned in the article I posted above? From the article;

Quote
One source suggests that JSF may be running into high-angle-of-attack handling problems including “abrupt stall.” Lockheed Martin says that tests have allowed the designers to prevent such a problem “by incorporating design elements and developing fallback options, should the phenomenon appear during flight testing.”

Early F-35Cs will have spoilers on the outboard wing panels as risk mitigation during flight testing. F-18E/F and T-45 both experienced wing drop during flight testing and both platforms were subsequently fixed. If no problems are found in flight testing then the spoilers will be removed for production. This has nothing to do with F-35A or B.

The "Plain Hornets" have a lot of washout because of a flexy wing, to prevent control reversal by flexing or outer wing stall. Super Hornet went for less washout because it had a more rigid wing but then I guess this stall problem might give control reversals by stalling the outer wing.
I wonder if this has something to do with it.
I know next to nothing on this specific issue, I admit, just wondering out loud. Perhaps they went for too optimistic washout in F-35C, with the high amount of taper and all, that would explain why you would want little washout and would suffer from tip stalls.

 

[SOC]

True. In fact that could be a pretty nasty surprise, but it'd still be a niche role for it.

No more a niche role than the fleet air defense taksing of an F-14. It'd be the same basic mission, just done semi-autonomously with a very sneaky platform. Makes great sense over the straits of Taiwan, you can upload more ABM rounds into the AEGIS ships for BMD and anti-ASBM capability, while using the UCAVs as the main long-range A/A defense for the carrier group. Basically use them as bulk AMRAAM-D/JDRADM shooters.

 

[sferrin]

True. In fact that could be a pretty nasty surprise, but it'd still be a niche role for it.

No more a niche role than the fleet air defense taksing of an F-14.

Except that an F-14 could do CAP during the day. It could do WVR combat, and escort aircraft away from the battle group. I don't know how scared a Bear bomber crew would be of an unmanned aircraft flying off their wing.

 

[SOC]

The BEAR crew will have to think twice because this time they won't know where the shooter is. A BVR-shooting UCAV could still perform CAP to a degree, it depends on the systems involved.

 

[sferrin]

The BEAR crew will have to think twice because this time they won't know where the shooter is. A BVR-shooting UCAV could still perform CAP to a degree, it depends on the systems involved.

And then the link goes down. . .

 

[SOC]

Or your manned fighter could have an FCS failure. Next? You can always set the UCAV in wartime to operate in an IFF interrogation mode autonomously if the link fails. Anything not squawking gets shot at. Same principle as setting PATRIOT batteries to "auto-fire" mode. Look, it isn't an ideal solution, but it'd be far better than what they have now, if and when the JSF falls on its face.

 

[sferrin]

Or your manned fighter could have an FCS failure. Next?

A bit more likely that a signal gets jammed than a redundant FCS fails. Besides, the UCAV has the FCS issue as well.

You can always set the UCAV in wartime to operate in an IFF interrogation mode autonomously if the link fails. Anything not squawking gets shot at. Same principle as setting PATRIOT batteries to "auto-fire" mode. Look, it isn't an ideal solution, but it'd be far better than what they have now, if and when the JSF falls on its face.

I don't disagree that as an ancillary mission having it just because it's already there (like mounting NCADEs on strike F-16s) is not a bad idea. Banking on it is another thing altogether IMO.

 

[Woody]

Look, it (UCAVs for CAP) isn't an ideal solution, but it'd be far better than what they have now, if and when the JSF falls on its face.

...like the idea from the point of view of persistence, given the Rand Taiwan report but given certain persons efforts to hack Google, it's probable the same people would try to hack UCAVs. See below.

http://www.secretprojects.co.uk/forum/index.php/topic,2353.0.html

http://www.rand.org/pubs/monographs/2009/RAND_MG888.pdf

http://www.bbc.co.uk/blogs/thereporters/maggieshiels/2010/01/the_google_v_china_face_off.html

 

[Steve Pace]

In the meantime, on 2-2-10, Jon Beesley flight tested BF-3 - the 5th SDD F-35 to fly.

 

[Avimimus]

I don't know how scared a Bear bomber crew would be of an unmanned aircraft flying off their wing.

I'd be pretty scared if I were in the crew - The chances for accidental collision with a UAV are probably much higher.

 

[sferrin]

I don't know how scared a Bear bomber crew would be of an unmanned aircraft flying off their wing.

I'd be pretty scared if I were in the crew - The chances for accidental collision with a UAV are probably much higher.

Well, yeah maybe. On the other hand it'd be a lot easier to aim a turret at it and pop a few rounds in it. :-\

 

[LowObservable]

It's not just that the F-35 has developmental squawks. That's to be expected.

The problem is that it's a highly concurrent program. At this point in the F-22 flight test program, Congress was even holding out on LRIP, and they had to order two PRTVs (production representative test vehicles) to keep the line open. We're about to buy LRIP-5 of the F-35.

But that's OK (the program keeps saying) because modeling and simulation are so much better and flight testing is "validation, not discovery".

Result: the emergence of familiar problems undermines the whole rationale behind the way the program is being run.

 

[Vpanoptes]

I noted from todays AvWeek article by Amy Butler re (in part): the
F-35B: “ there is no immediate impact on either the U.K.’s ongoing participation in JSF or our future plans to acquire JSF.” This official also expresses confidence in the posture taken by the Defense Dept. and says “the measures already planned ensure the JSF program will deliver within the revised cost estimates . . . . The immediate impact is limited to the U.S. JSF, not the U.K. Joint Combat Aircraft [or the] planned timescales.” Questions/comments:

Even parsing typical MOD/DOD multispeak, how can this be interpreted?

1) Are the Brits fated/committed to go down with the F-35B ship,
regardless of cost? At what point does a stiff upper lip restrict the
intake of O2 necessary for proper brain function?
2) Have they made only a partial committment (w/exit option)to 50, er...
42, er... 36 a/c as costs continue to increase and schedules (likely)
slip (again?)
3) Or are they (as history has demonstrated repeatedly) really very
clever ("I have a cunning plan..."), having cut some sort of contingency
deal with the USN for a slice of the X-47 pie? Could this even operate
off the QE sans catapults? ???

Answers/Comments?

 

[red admiral]

So far the UK has committed to buy three SDD F-35B aircraft, that's it. Lot's of options are being talked about for actual production aircraft; mostly which aircraft (STOVL or CV) and how many. I don't know when an announcement will be made, probably put off until the SDR later in the year. Mostly likely option seems to be around 50 STOVL during the late 2010s/early 2020s and probably not getting around to buying any more.

 

[shedofdread]

As I said before, 'dont sell the Harriers'. Oh, and I'll believe HMS Unlikely and HMS Improbable when I see them both under steam.... Though it can be quite easily argued we need them.

However, getting back to the issue of flight testing. I work for a small company in the aerospace / defence sector and we have software that accurately models flight behaviour so why did this apparent tip stall issue catch out two of the biggest primes? I will freely conceed, however, that I haven't heard the whole story ref that one so...

S

 

[sferrin]

As I said before, 'dont sell the Harriers'. Oh, and I'll believe HMS Unlikely and HMS Improbable when I see them both under steam.... Though it can be quite easily argued we need them.

However, getting back to the issue of flight testing. I work for a small company in the aerospace / defence sector and we have software that accurately models flight behaviour so why did this apparent tip stall issue catch out two of the biggest primes? I will freely conceed, however, that I haven't heard the whole story ref that one so...

S

What are you talking about? Where has it been reported that the F-35 has a tip stall problem?

 

[Trident]

It's not just that the F-35 has developmental squawks. That's to be expected.

The problem is that it's a highly concurrent program. At this point in the F-22 flight test program, Congress was even holding out on LRIP, and they had to order two PRTVs (production representative test vehicles) to keep the line open. We're about to buy LRIP-5 of the F-35.

But that's OK (the program keeps saying) because modeling and simulation are so much better and flight testing is "validation, not discovery".

Result: the emergence of familiar problems undermines the whole rationale behind the way the program is being run.

Agree, it's a highly ambitious project so a little more margin for error would probably not have gone amiss.

 

[shedofdread]

As I said before, 'dont sell the Harriers'. Oh, and I'll believe HMS Unlikely and HMS Improbable when I see them both under steam.... Though it can be quite easily argued we need them.

However, getting back to the issue of flight testing. I work for a small company in the aerospace / defence sector and we have software that accurately models flight behaviour so why did this apparent tip stall issue catch out two of the biggest primes? I will freely conceed, however, that I haven't heard the whole story ref that one so...

S

What are you talking about? Where has it been reported that the F-35 has a tip stall problem?

In the light of re-reading (and not whilst 'working'), I'd like to retract my comments re tip stalls (potential transonic wing drop is a different matter that should still have spotted). However, I'll never be a fan of the general concept / layout of the Yak 41 or the F35.

I know this is slightly off topic but it's my understanding that there was a L/O P1216 variant proposed. Surely that would have been better than all this mucking about with geared lift fans? Oh, and don't forget, no 'viffing' in an F35.

Once again, I'd like to appologise for getting 'my wires crossed'.

Regards,

S

 

[fightingirish]

In the meantime, on 2-2-10, Jon Beesley flight tested BF-3 - the 5th SDD F-35 to fly.

Video: http://www.youtube.com/watch?v=ZTIWJnSKYrk

 

[Ian33]

That is noisy beyond belief! goodness me - that sounds like its got three engines tucked in there not one! Nice to see it getting some air time though.

 

[sferrin]

That is noisy beyond belief! goodness me - that sounds like its got three engines tucked in there not one! Nice to see it getting some air time though.

I take it you've never heard an F-4, or F-105.

 

[bobbymike]

As a proponent of a strong national defense I want the US to have massive technology superiority. But it is easy to forget how incredibly complex the F-35 program is, we should almost look at it as three separate aircraft all being produced at once. I pray for every airman, sailor and soldier on the ground that this aircraft will eventually protect.

I am often reminded of a "complexity" problem the US would experience trying to build SDI. Critics said the defense system would require "over one million lines of software code" and no program that complex could ever work. Well fast forward and I think I remember reading somewhere (please feel free to correct me) that the F-35 program has or will have over 20 million lines of code.

 

[sferrin]

As a proponent of a strong national defense I want the US to have massive technology superiority. But it is easy to forget how incredibly complex the F-35 program is, we should almost look at it as three separate aircraft all being produced at once. I pray for every airman, sailor and soldier on the ground that this aircraft will eventually protect.

I am often reminded of a "complexity" problem the US would experience trying to build SDI. Critics said the defense system would require "over one million lines of software code" and no program that complex could ever work. Well fast forward and I think I remember reading somewhere (please feel free to correct me) that the F-35 program has or will have over 20 million lines of code.

Hell, WINDOWS has more than that. Apparently, "there were 20million lines of code in Win2000, 25mil in XP and 50m lines of code in Vista. " No idea on Windows 7.

 

[LowObservable]

Your flight control system has encountered a problem and needs to close. Would you like your next of kin to report this error to Lockheed Martin technical support?

The issue is how much of the software has to be certificated as airworthy and how long that will take.

 

[elmayerle]

Why is the F-35C anchored down? It rolled out months ago.

I've read (At the Ares blogs?) that the F-35C wings may need to be strengthened as it may not be strong enough to handle cats and traps. I know it uses the same spar as the B and C, which is why with the added wingtips it actually has a lower max G load capability. But the only thing I can figure out is the spar was so optimized, that the weight growth caused the spar to exceed the limits or they just screwed it up royally. That's just my opinion based on what I've read. It may just be they're actually still waiting for "flight ready" parts. Whatever the case, LM has created a huge clusterf*ck with the F-35 program. I really think more heads need to roll on this program, than what happened a week or two ago.

*blink**blink* The F-35B and F-35C share common wing spars? I find that difficult to believe since the spars run from one outer surface interface to the other and the 'B and 'C have different contours in the center where the wings and fuselage sections mate up; since the 'B and 'C have, rather different profiles.

 

[Sundog]

*blink**blink* The F-35B and F-35C share common wing spars? I find that difficult to believe since the spars run from one outer surface interface to the other and the 'B and 'C have different contours in the center where the wings and fuselage sections mate up; since the 'B and 'C have, rather different profiles.

That's something I often wondered, but I was lead to believe, in AvWeek I think is where I had read it; yes I know, they don't always get it right, but it was stated that all the aircraft share the same spar and they use extensions for the C-Model. Having done structural engineering, I thought maybe they were over-lapping the spars (Horribly inefficient and just asking for problems) for the extensions.

Or it might have been in Combat Aircraft, which I know to take with somewhat of a grain of salt.

As such, it was reported it has a lower G capability, than the others. So are you saying that the C has a 9G capability? If so, it should have some excellent maneuvering ability, albeit, probably a lower top speed. Also, does the C have bigger wing tanks as well? If it does, the combination of fuel and the higher aspect ratio should give it incredible range, as the fuel fraction of the A model is quite remarkable when compared to other fighters already, at least based on what's been released. Will the Super Hornets be able to keep with them?

 

[Vpanoptes]

Hello -
Relatively new to the site, only a few posts, not in the Aerospace business, just an interested onlooker, please excude my naivete. I have read most of Sweetman's recent stuff on AvWeek, as well as a fair bit of background on the -35, and while a number of questions occur to me, here are three+ I would be interested in hearing some (informed) comment on.

1) Is there any conceivable point (cost-wise, major development problem wise) that could cause the UK to bail on the STOVL version? If so, what would you guess/speculate that to be?

2) I know the above isn't an option for the USMC, having essentially no Plan B and betting the farm on this platform, but what about the -35C model? As above, what are the circumstances (hypothetical) that could/might trigger a major rethink and qualified/limited bailout by the USN?

3) How has the -35A managed to (relatively speaking) avoid a lot of the
bad press that seems to be rapidly increasing on this aircraft?

Thanks for your input

 

[Steve Pace]

An interesting view of BF-01.

 

[Sundog]

That is a cool picture. It would be nice to know how fast he was flying when that was snapped. 120 knots? Cool, none the less. It's first vertical landing is still supposed to happen this month, isn't it? BTW, does anyone besides Evan know what the duct is for above the right intake? Environmental Systems, cooling the electronics?

I single out Evan, because he probably knows, but I don't know if he can say.

Edit:
A lot of my questions, at least for the initial tests, are answered here. This is awesome, because you hear the test pilot calling out what he is about to do and see it. On the "Flight 29" video, you can here the chase planes, I'm assuming another F/A-18, bitching Betty call, "Altitude, Altitude." I also never really noticed the forward rake on the fan doors on the belly until watching these videos.

One more thing, looking at the pic from that site of the F-35 with it's missile bays open, does it have to open both doors to fire the AIM-120, or would it just open the door it's attached to to fire it?

 

[Stuka]

The duct is the fuel/air heat exchanger. http://www.codeonemagazine.com/archives/2008/articles/apr_08/f35transition/x-35b_top.html Last paragraph of letter H

BF1 has made 3 STOVL mode short landings this past week after having been snowed in earlier but no pictures or videos have surfaced. They will probably wait until first VL and release a lot of stuff at once. If we can believe what LM said earlier, they are now about 2-3 flights away from VL.

A few recent videos:
http://www.jsf.mil/video/f35test/BF-01_Flight_29.wmv
http://www.jsf.mil/video/f35test/BF-01_Flight_30.wmv
http://www.youtube.com/user/LockheedMartinVideos#p/a/u/0/EuXk9RGPpNM

 

[Sundog]

Here's a great video that shows the operation of the F-35's STOVL mode from the cockpit, which is very cool!

 

[Stuka]

Slow landing at 130 kts.

http://www.youtube.com/watch?v=rbO3Gd0q9aw

 

[Sundog]

That fan door makes for one hell of an airbrake! Cool video.

 

[AeroFranz]

Does anyone know the reasons for switching from the bi-fold lift fan doors to this ram scoop?

From what I know, the ram scoops are great to redirect flow in transition, but they increase blockage in hover. So much so that some aircraft that used them in the past (Yak-38, Mirage III-V...) had longitudinal louvers on the door that could be flipped open in hover.

I'm assuming weight was not the issue because I'm pretty sure the current door is beefy and sees higher loads than the old system.

 

[Sundog]

Does anyone know the reasons for switching from the bi-fold lift fan doors to this ram scoop?

From what I know, the ram scoops are great to redirect flow in transition, but they increase blockage in hover. So much so that some aircraft that used them in the past (Yak-38, Mirage III-V...) had longitudinal louvers on the door that could be flipped open in hover.

I'm assuming weight was not the issue because I'm pretty sure the current door is beefy and sees higher loads than the old system.

If you look at the door on the F-35, it opens all the way near to vertical, unlike the Yak's and Mirage's, which is probably why the F-35's door doesn't require louvers. It can obviously entrain a larger mass flow than those much earlier designs were capable of with their limited max open positions.

 

[AeroFranz]

Thanks Sundog, I didn't know that. As you said yourself, that is unlike any other previous fan inlet design. Interesting.

 

[fightingirish]

Does anyone know the reasons for switching from the bi-fold lift fan doors to this ram scoop?
I'm assuming weight was not the issue because I'm pretty sure the current door is beefy and sees higher loads than the old system.

The new door did actually add weight.

Lift Fan Inlet
The lift fan inlet doors were changed from a bi-fold, side-hinged configuration to a single, aft-hinged door. The change added some weight, but significantly reduced lift fan flow distortion, which increased lift fan performance and operability.

Auxiliary Inlet
The auxiliary inlet provides an additional source for low distortion air for the engine during powered lift operation. When open at slow speeds, about sixty percent of the air at the engine face comes from the auxiliary inlet. The X-35B had a smaller opening with two doors hinged on the centerline of the aircraft. The F-35B has two doors hinged on the outboard sides of the opening. The change improves inlet flow performance. The increased size reflects the largest inlet within the structural constraints of the aircraft.

Click on the photos at the bottom of the following page to view the changes.
Source: http://www.codeonemagazine.com/archives/2008/articles/apr_08/f35transition/index.html