The F-35 No Holds Barred topic

[sferrin]

Fo' real? I'm curious to know if they are stressed for the same load factors, and the relative TOGW figures. You can strengthen a lot of structures and get more wing for the weight of a lift fan, swiveling nozzle, roll post, added doors.

If you have something better than "na-uhhh" I'm all ears. I won't be holding my breath though.

 

[uk 75]

This has been a fascinating thread.

As a complete layman I read all with great interest. The exciting thing is that we do not know yet whether the JSF is going to turn into a Phantom (truly great and a massive success), an F111 (remarkable if used in the right variant, rubbish otherwise), or a complete lemon which sucks up vital funds that could have been used for more effective platforms.

I think we still have a few years to go before the verdict comes in....

UK 75

 

[chuck4]

That misses the point. The requirements for the f-35c had relatively little impact on the design and configuration of F-35A. the particular requirements of f-35c mainly resulted in features unique to f-35c.


Not so with f-35b requirements. The very layout of every f-35 is dictated by the requirements of f-35b. What's worse is much of the delay in f-35 program wasn't because f-35a or c. They would have done fine in the first iteration. The delay was caused by f-35b not being able to meet its requirements. So f-35b had to be substantially modified, and to keep up the pretense that trying to meet the 400 plane f-35b requirement with a run that consist mainly of 2000+ f-35a wasn't a mistake, f-35a was REDESIGNED so it retains commonality with parts that had to be changed to meet f-35b requirements.

Exactly how different do you think the JSF would have been without the STOVL requirement? It would still have one engine (as per the largest customer's demand). It would also still have the same LO requirements along with the requisite demands for internal weapons and fuel.

And not to be too cynical here, but a non-STOVL JSF would probably still be just as behind schedule and over ebudget.

Without VTOL requirement, the main engine would have been placed conventionally, that is behind the main structural bulkhead that carries the landing gear and one of the main wing spars like every other modern jet fighter. But the VTOL requirement demand the engine nozzles be placed close to the center of gravity. So the engine is place much further forward than is usual. This makes it necessary to split a single weapon bay into two, at expense of added weight to all three versions. The need to recess the exhaust forward also rules out axial symmetric thrust vectoring in all three versions. The need to cut structural members to accommodate the down swiveling of exhaust nozzle forced the adaptation of what is effectively a twin boom tail configuration, with structurally inefficient and therefore heavy.


All this forced thetargeted performance of f-35a and c be lower than necessary.


But even so the VTOL version was overweight late into pre development stage, when production was already scheduled to begin. The other two version at the time can meet their requirements with existing weight. But to save weight and retain commonality the bomb bays for all three version had to be redesigen and made smaller, delaying all three versions. That still wasnZ't enough. Addition structural changes were needed. Again, commonality demanded all three fighter versions change, thus delaying the project still more.

 

[TaiidanTomcat]

I don't think its much of a stretch to say that if you took 1/3 of the program away it would go faster. Like taking 8 miles off a marathon. Personal best!

Heres the thing with the B. It was a requirement. Its really that simple. You know what would have made the F-22 easier? 200 pages of requirements instead of 300 pages.

The UK is one of the leading JSF partners, and they had a STVOL requirement. The Italians who also contribute a lot of money also have a STOVL requirement. You want to know how to move an apartment fast? Leave all the heavy crap at your old place. No TVs, Couches, Beds, Sofas, chairs, tables, but thats not really an option is it? How far do you get in life when you do the easy 66 percent and then quit? D student forever.

The Naval Variant may start having problems too, after they get the tailhook squared away and start crash landing it onto some decks. If it encounters problems do we cancel that too? Should the JSF consist of just the A version because that's the "easiest?"

So it really doesn't phase me when people say "You know the B really messed things up" did it? It was one third of the program, based on importance to allied fleets, it will be even more than just one third. Its not a race, its about getting it right and meeting the requirements. Moreover the redesign paid dividends in the form of a lighter aircraft overall. ITs a shame the JSF got lighter and better I know.

It is what it is. The F-35B is reality. You can argue all day as to whether it should have been included in the JSF requirement, but ONCE IT WAS, it was going to happen as obligated by requirements. Requirements are requirements, not suggestions.

Also 503SGT there have been grumblings in the Navy about canceling the C variant and letting the B variant live, I think its very near sited on the USN's part but its "Boeing's Navy" And naval aviation is culturally convinced that airplanes never flew over water until someone invented twin engines. ;D The other thing I have noticed to is that Naval Aviation is beyond reproach. You can't question it anywhere. It doesn't matter how expensive, inefficient, or risk-averse it is.

 

[chuck4]

No issue with having to answer o foreign contributors for the VTOL feature if we were smart enough not to have included the VTOL feature in the first place. In any case, joint programs in which multiple partners contributed, but which had to cancelled due to key partner pulling out, is quite common and shouldn't fluster the Italians, who had several such experiences in the last few decades.

 

[AeroFranz]

The penalty associated with carrier suitability is difficult to asses on an apples to apples basis because you rarely start with the same aircraft and same requirements as a land counterpart. However, there are some generalizations that you can make based on historical trends.
The picture is from SAWE paper 2330, it is a little bit dated since it's from 1996 but still benefits from about 85 years of naval aviation experience. It was presented by Frank O'Brimski of the conceptual design division NAVAIRSYSCOM.
Anyway, for carrier aircraft designed from scratch (not land based derivatives), the sum of navy specific requirements tends to drive airframe weight up 15%. You also end up with lower load factors to try to mitigate the penalty (as posted by 503rdsgt; thanks for finding that). The fact that the B-model has an even lower normal factor than the C should tell you something about how desperate the designers were to keep structural weight down, an intrinsic problems with VTOL where you are not going anywhere unless T/W > 1.2. It also tells you that commonality is out the door, since it makes no sense to lower your load factor unless you have lighter, customized bulkheads for your specific model.
Anyway, I welcome weight figures that show that the VTOL specific components add less than 15% to the airframe weight. This will still be an imperfect comparison, but for now it's the best I can think of to compare the two versions.

 

[SpudmanWP]

Eglin AFB has logged it's 300th sortie on the 21st, less than a month after it's 200th (Aug 27th).

http://www.flightglobal.com/blogs/the-dewline/2012/09/33rd-fw-flies-300th-f-35-sorti.html

 

[TaiidanTomcat]

No issue with having to answer o foreign contributors for the VTOL feature if we were smart enough not to have included the VTOL feature in the first place.

IT was also a USMC requirement.

Chuck I am sorry to say, but you are not the first person to think the VSTOL requirement should have been separate, but Its not and will never be, so I don't know why we are going on about it. You know the F-22 would have been cheaper if we bought 400 of them. We could station them in "Shouldville," in the valley of "if only" Right next to the tower of "coulda, shoulda woulda"

A separate "No VSTOL" JSF belongs in the "what if the YF-23" were selected type threads. ITs fun to ponder, but it isn't reality.

This topic has been covered, the horse is beaten, its dog meat, its glue. Bill Sweetman has even gone so far as to say cancel the B and the Marine Corps period, Im sure he would also include the Royal and Italian navy in there if you give him the time. So he not only wants to abolish the B but disband all forces associated with it, along with all the people who had a hand in the entire JSF program, along with the aircraft itself. He's a bit dramatic, and you won't top him.

In any case, joint programs in which multiple partners contributed, but which had to cancelled due to key partner pulling out, is quite common and shouldn't fluster the Italians, who had several such experiences in the last few decades.

So its ok to screw em? awesome.

 

[SpudmanWP]

The original F-35A requirement was for two 1k JDAMS. The 2k JDAM requirement was only for the F-35C.

After the SDD contract was awarded, it was discovered that they could save a lot of time & money by going all 2K due to the small difference in size from the 1k to the 2k.

Their mistake was to also apply that logic to the B and the B had to go back to the 1k during SWAT.

The 2k ability gives you the ability to carry internal JSOW, JSM, SDB, etc that you would lose if you limited it to 1k. This also is a likely reason that they went all 2k.

btw, The B is 1.5k internal, not 1k, which is why it can still do the SDB.

 

[sferrin]

So its ok to screw em? awesome.

Yeah the UK was real happy when we cancelled Skybolt.

 

[1st503rdSGT]

Without VTOL requirement...

This language is for 13 year-olds who think they know everything about the F-35 from video-games http://www.youtube.com/watch?v=OmTyDZRhSUg ; you obviously know better. Try getting the nomenclature right before you go on.

As for the technical changes you mentioned, I think you're getting things mixed up with the X-32. The F-35's engine is still pretty much at the back where it's supposed to be; but if that's not enough for you, consider that much of your argument is still irrelevant given advances in flight control, which make it possible to fly a brick if one wants.

In any case, I find all this crying about what could have been rather ironic. During the cold war, pundits were constantly moaning about the teen-series of fighters NOT having STOVL capability. : I suppose the professional complainers will always find something.

 

[John21]

The 2k ability gives you the ability to carry internal JSOW, JSM, SDB, etc that you would lose if you limited it to 1k. This also is a likely reason that they went all 2k.

btw, The B is 1.5k internal, not 1k, which is why it can still do the SDB.

Shouldn't it have been able to carry SDB anyway, be it at 1k, 1.5k or 2k since they are only a bit over 250 pounds a piece?

 

[SpudmanWP]

A fully loaded BRU-61 is 1460 lbs and is 143" long while the GBU-32 is 1031 lbs and 120" long.


http://www.cobham.com/media/58974/bru-61a-900-071-0209.pdf

 

[SlowMan]

The original F-35A requirement was for two 1k JDAMS. The 2k JDAM requirement was only for the F-35C.

All F-35 models should have stayed at 1,000 lbs JDAMs, as the 2,000 lbs required widening of the airframe that triggered the weight increase. Which in turn forced a thrust increase and more fuel capacity to power the thirstier engine, which increased the weight again.

Had Lockheed started with F-35B(They started with F-35A as basis for all three models) then convert finished F-35B into A and C, the JSF program wouldn't have turned into such a mess.

 

[SpudmanWP]

All F-35 models should have stayed at 1,000 lbs JDAMs, as the 2,000 lbs required widening of the airframe....You are mistaken.

The diameter difference between a 1 k JDAM and a 2k JDAM is 4 inches (the GP one, not the bunker buster which is only an inch) and the fin-span difference is 6 inches (before you say it, that is not a total of 10 inches).

http://www.designation-systems.net/dusrm/app5/jdam.html

You also lose a LOT of capability by going with a 1k bay (as mentioned above).

Had Lockheed started with F-35B(They started with F-35A as basis for all three models) then convert finished F-35B into A and C, the JSF program wouldn't have turned into such a mess.

This method would have taken much longer than the current schedule. It would have also cost more to keep current F-16/18s flying due to having to wait for the B to finish development.

 

[SlowMan]

The diameter difference between a 1 k JDAM and a 2k JDAM is 4 inches (the GP one, not the bunker buster which is only an inch) and the fin-span difference is 6 inches

An airframe fuselage width difference of 12 inches PLUS the structural reinforcement needed to support almost 1 ton of additional weapons weight translates into a weight difference of about 1 ton. Not to mention that a lower drag narrow F-35 with a less thirsty engine could fly longer on same fuel, or need a smaller fuel tank to fly the same distance.

Compare the X-35 to the F-35, and the F-35 is a much wider, taller aircraft. With the X-32, what you saw was what you were going to get, complete with internal weapons bays.

This method would have taken much longer than the current schedule.

The current schedule was impossible to achieve to begin with.

It would have also cost more to keep current F-16/18s flying due to having to wait for the B to finish development.

Which is what happened anyway with the concurrency development. A 20 year development cycle was unavoidable whether they decided to develop sequentially or concurrently, only that the sequential development model would have been much cheaper by not repeating engineering errors three times over.

The JSF program should have started with F-35B, then convert finished F-35B into A and C. If they realized during the course of development that the F-35B was going to be unfeasible, then they should have dropped the vertical landing requirement and made it a STOL aircraft by fitting it with canards and a thrust vectoring engine instead.

 

[1st503rdSGT]

With the X-32, what you saw was what you were going to get

Did you really just write that?

What we saw.

What we were gonna get

The JSF program should have started with F-35B, then convert finished F-35B into A and C. If they realized during the course of development that the F-35B was going to be unfeasible, then they should have dropped the vertical landing requirement and made it a STOL aircraft by fitting it with canards and a thrust vectoring engine instead.

Right, because that would have been so much easier than what they actually did. BTW, did any of the services mention desire for STOL? Ever?

 

[SlowMan]

What we were gonna get

That is just the addition of horizontal tails worth 500 kg in additional weight.

Right, because that would have been so much easier than what they actually did. BTW, did any of the services mention desire for STOL? Ever?

The Royal Navy paid Lockheed to explore SRVL flight mode for its F-35B, so yes the Royal Navy would have lived with STOL only if the QE class could handle it.

Not sure if the USMC would accepted such an arrangement as the LHDs in their current form maybe too short for STOL operation. But buying a new set of 330 m long LHDs maybe cheaper than trying to make the F-35B's STOVL work.

But an STOL F-35 with canards and a thrust vectoring engine would work on 330 m long ships no doubt.

 

[TaiidanTomcat]

With the X-32, what you saw was what you were going to get

Did you really just write that?

Wasn't Boeing already talking about the redesigned tail before they even made their first flight in the X-32 as well? It was just too late to change the prototype at that stage.

 

[SpudmanWP]

1. The B would have been limited to 1.5k, not 1k due to SDB requirements, so the increase was only 33% (1.5k --> 2k), not 100% (1k --> 2k).

The bays (and their 2k loads) did not make the F-35 any wider than was already planned.

Take a look at the X-35 which did not have ANY bays.

and compare that to the F-35

Another 3-view of the proposed F-32:

 

[TaiidanTomcat]

That is just the addition of horizontal tails worth 500 kg in additional weight.

Other than that major redesign before it was even past the prototype stage though, it was just perfect. Thats why it won.

lame problems like an an additional 500 KG mean nothing when you are already having to strip parts to hover too, Amiright?

 

[1st503rdSGT]

What we were gonna get

That is just the addition of horizontal tails worth 500 kg in additional weight.

"Just?"

Right, because that would have been so much easier than what they actually did. BTW, did any of the services mention desire for STOL? Ever?

The Royal Navy paid Lockheed to explore SRVL flight mode for its F-35B, so yes the Royal Navy would have lived with STOL only if the QE class could handle it.

Not sure if the USMC would accepted such an arrangement as the LHDs in their current form maybe too short for STOL operation. But buying a new set of 330 m long LHDs maybe cheaper than trying to make the F-35B's STOVL work.

But an STOL F-35 with canards and a thrust vectoring engine would work on 330 m long ships no doubt.

In other words, not really.

 

[SlowMan]

Take a look at the X-35 which did not have ANY bays.

Which was really an unfair comparison because X-32 did have two.

and compare that to the F-35

I will give you a much better width comparison of X-35 vs F-35.

Actual X-35C at Patuxent Air Museum

F-35B

You can tell F-35 is a much fatter jet relative to X-35 due to the inclusion of weapons bay and additional fuel tanks.

 

[1st503rdSGT]

You can tell F-35 is a much fatter jet...

Oh, God. :

Mmm, sleek!

 

[SpudmanWP]

You can tell F-35 is a much fatter jet relative to X-35 due to the inclusion of weapons bay and additional fuel tanks.

When making comparisons, you might want to try similar camera angles and lenses so that you do not accidently obscure the facts.. oh wait, nevermind

 

[TaiidanTomcat]

Its just refreshing to hear the F-35A blamed for once

 

[SlowMan]

When making comparisons, you might want to try similar camera angles

Same frontal aspect shot at the human eye height.

The F-35 is a much fatter and draggier jet compared to the X-35, accept the fact.

 

[TaiidanTomcat]

When making comparisons, you might want to try similar camera angles

Same frontal aspect shot at the human eye height.

The F-35 is a much fatter and draggier jet compared to the X-35, accept the fact.

you happen to know the difference off hand?

 

[GTX]

A comparison between the X-35 and the F-35 from CodeOne Magazine:










I have seen both 'in the flesh' as well and I love the more pugnacious, purposeful look to the F-35! ;D


Regards,


Greg

 

[Triton]

When will unmanned platforms be able to do the job of the F-35 or supplement the F-35 fleet?

 

[GTX]

When will unmanned platforms be able to do the job of the F-35 or supplement the F-35 fleet?

It depends...define the mission?

 

[SpudmanWP]

Same frontal aspect shot at the human eye height.

The F-35 is a much fatter and draggier jet compared to the X-35, accept the fact.

You still used a deceptive camera shot. You can clearly see this when you look at the cheek areas outboard of the inlets. On your shot of the X-35 the are virtually nonexistent due the the camera angle but can be clearly seen in either my shot or the Code One provided comparison.

 

[1st503rdSGT]

The F-35 is a much fatter...

Hmm, "fat." A *technical* term you keep bringing up. Maybe you should see someone about that.

 

[1st503rdSGT]

When will unmanned platforms be able to do the job of the F-35 or supplement the F-35 fleet?

My guess is that we'll see semiautonomous UCAVs starting to become operational in the mid-late 2030s; that's assuming serious development begins very soon with all the requisite competitions and fly-offs... followed by the usual development-hell for the winner (and we thought the F-35's software was a headache).

 

[GTX]

Hmmm...fat...could you please define that? Maybe the following will be of assistance:

 

[1st503rdSGT]

Hmmm...fat...could you please define that? Maybe the following will be of assistance:

You forgot to put operational payloads on the other fighters.

 

[TaiidanTomcat]

By Alvis 3.1

 

[quellish]

When will unmanned platforms be able to do the job of the F-35 or supplement the F-35 fleet?

When there is money available to build them. Boeing and Lockheed have invested corporate funds into UCAV development, while NG has been working the Navy UCAV program as well as some related efforts of their own. For some roles the technology readiness level is in line with values for low risk procurement. For example, land based SEAD and penetrating strike are well within reach. Carrier based penetrating strike is one of the aims of the Navy program - the Navy hopes to finally have an aircraft capable of filling that need (i.e. the A-12 mission).

 

[LowObservable]

Those split frontal profiles, F-35-versus-others: First, the eye perceives dimensions better than area. Second, we're all used to seeing front views so we have a symmetry bias. (The attached is rough and ready, but doesn't tell quite the same story, does it?) Third, 2-D views of 3-D objects don't tell the full story by a long chalk.

Code One front and side aspect comparisons are helpful.

Note particularly, in the side profile, how the body upper and lower mold lines diverge vertically behind the inlets on the F-35, to a much greater degree than on the X-35. In the front profile, it is clear that the resulting greater depth is sustained across the width of the airplane. If we define "fatter" as "having a greater cross section relative to length" the case is closed.

Now, whether one likes the muscular look or not is a personal matter...

https://www.youtube.com/watch?v=FVY0Hy-D7XE

...but does the airflow at Mach 1 share your opinion?

Now, if anyone can produce evidence that you could have put 2 x 2k bombs in the X-35 OML, I'm all ears.

Of course that isn't conclusive. The CDAs were there to demonstrate traceability to the PWSC, and there were no rules that said that they had to look the same. The assessment criterion was whether the CDAs performed as predicted, because that was supposed to give the customer confidence that the design process was sound and that the proposed design could be built.

Pity that it did not work out that way.

 

[Evil Flower]

What are CDAs and PWSCs?