Alternate history: Boeing won JSF

[helmutkohl]

Boeing and Lockheed beat out McDs, GD, and some other companies to become the two finalists for JSF.

Boeing went with a somewhat more conventional engine arrangement, but an unconventional shape
Lockheed was opposite and chose a more novel engine arrangement, but had a shape more similar to the F-22

In the end the Lockheed version was chosen.

However in this alternate history, the Boeing design was chosen.
With Boeing winning the JSF competition, how different do you think the following would be

1. Development into a production version. the X-35 took some time to mature into the F-35, and even as the F-35 people are still critical of it today. Would the X-35 be better or worse? One thing known is that the X-35 would have changed to a new design towards a conventional delta and tail over the all delta version. Although supposedly the delta wing was quite advance
2. Influence on other designs. the F-35 really popularized the DSI inlet and helped cement the basic F-22 shape as the "standard" for 5th gen aircraft. But would this change had the Boeing design won? Would the Korean and Chinese planes look the way they do today or would they end up being more similar to the X-32?
3. Would it affect exports or would the market be roughly the same?
4. How would it affect other procurement? Would the F-22 keep going on in order to keep Lockheed busy with orders? the US is often about balancing its major aviation companies, Boeing, Lockmart, and NG. would a Boeing win influence the trainer decision for example?

 

[SteveO]

I always wanted the F-32 to win and in my ideal fantasy world the F-32 would have been cheaper through increased commonality between the 3 variants. The STOVL variant would have kept the 2000 pound bomb bay capability due to the chunkier design having more internal volume. I also like to think that although the direct lift system wasn't as capable as the F-35 lift fan it would have been more than adequate for STOVL carrier operations and good for STOL on land (and cheaper too!). Maybe the simpler lines of the F-32 would have been a benefit when it came to low observable maintenance?

Reality is a let down

 

[Richard N]

Considering the major malfunctions Boeing has had since they were defeated in the JSF Competition, I do not see how they could possibly have made a success of the X-32. Their three most public failures being the 737 Max, KC-767, and Starliner along with the CEO leaving under the 737 Max cloud. Terrible examples of "Wrong Stuff".

 

[overscan (PaulMM)]

A better chance of different outcome success would be to not eliminate the McDonnell-Douglas / Northrop / BAE Systems design.

 

[Archibald]

Perhaps the early variant that had a lift-fan like the F-35 but driven by the engine hot gases, rather than a shaft. Ryan XV-5A rather than F-35, kind of. But they failed to make it work.

The later variant that lost had lift jets and was hopeless (from memory).

 

[Richard N]

Something I heard discussed about the F-35's fan drive shaft is that it could be used to run a generator to make large quantities of electric power for future weapons.

 

[Archibald]

I remember that, too - there were talks about lasers.

 

[Colonial-Marine]

Perhaps the early variant that had a lift-fan like the F-35 but driven by the engine hot gases, rather than a shaft. Ryan XV-5A rather than F-35, kind of. But they failed to make it work.

The later variant that lost had lift jets and was hopeless (from memory).

Why do you say it was hopeless? Supposedly the lift jet solution wasn't exactly popular, probably due to the heat concerns, but I don't see why it couldn't work. The rest of the design looked promising, at least from the outside. McDonnell Douglas may not have been in their prime anymore but Northrop was on the team and certainly had a good understanding of low RCS design.

I'd have to go with the theory that Boeing was selected as the "low risk" STOVL method as it essientally functioned the same as the Harrier did. Of course the Harrier was much lighter and less capable. In retrospect it might seem that they were trying to achieve too much with that method.

 

[Richard N]

The lift jet solution was not popular because it couldn't do the job! The X-32B's VTOL performance was so marginal that it couldn't perform at Edward's hot and high location so they had to take it across the country to PAX River at sea level to have dense enough air for the engine to have enough performance to lift the B with many parts stripped off to save enough weight just to get off the ground vertically. The Boeing team had people with the most VTOL jet experience in the world and wound up with an airplane that could only VTOL at sea level with parts missing. That is an indication that lift jet had reached the peak of its evolution.

It was an advantage for LM to have started with a clean sheet that made them look at the problems of lift jet and solve those along with looking at new ways to increase VTOL performance beyond what the Harrier had done. LM's lift fan innovation improved VTOL performance by greatly increasing and cooling the air mass directed at the ground. A side benefit of the column of air drawn into the lift fan was a ram air effect into the auxiliary air intakes that increased engine performance during VTOL. This air was cool and free of exhaust gas recirculation that is a known problem of Harriers.

The X-35B with its lift fan went on to do the first VTOL supersonic flight. The X-32B could barely get off the ground.

 

[Mike OTDP]

I know that some of the people involved were convinced that the Boeing design was, in fact, superior. I don't have a dog in that fight. WRT the sensor problems, both companies went with the same radar/sensor vendors...Northrop-Grumman. A company that has a very long track record of software issues.

The real joker in the deck would have been separating out the USAF, USMC/UK, and Navy airframes into entirely separate programs. Common powerplant and avionics. Which in a modern tactical jet are around 75% of the total cost, possibly more. This isn't 1950, the airframe is almost trivial compared to the total program.

Now, as to the ripple effect...whoever won JSF was likely to be out of the running for a lot of other contracts. I could easily see Lockheed getting another 80-160 F-22s as a consolation prize, followed by a much better shot at the USAF trainer contract. And they would have a lock on the P-3 replacement program.

 

[helmutkohl]

I know that some of the people involved were convinced that the Boeing design was, in fact, superior. I don't have a dog in that fight. WRT the sensor problems, both companies went with the same radar/sensor vendors...Northrop-Grumman. A company that has a very long track record of software issues.

The real joker in the deck would have been separating out the USAF, USMC/UK, and Navy airframes into entirely separate programs. Common powerplant and avionics. Which in a modern tactical jet are around 75% of the total cost, possibly more. This isn't 1950, the airframe is almost trivial compared to the total program.

Now, as to the ripple effect...whoever won JSF was likely to be out of the running for a lot of other contracts. I could easily see Lockheed getting another 80-160 F-22s as a consolation prize, followed by a much better shot at the USAF trainer contract. And they would have a lock on the P-3 replacement program.

Yeah I wonder if the Navy, marines and USAF could choose separately.. would they all choose the X-35? or would they choose differently?

in the last competition, the USAF chose the YF-16 which became the F-16. the Navy ended up choosing the loser, the YF-17 and modified it into the F-18.

At the same time, I've also read that it was the Navy, whose last minute requirement changes, is what screwed over the Boeing X-32 entry.
the Navy wanted more agility and a lighter air frame at the last minute. So Boeing had to change their design from a pure delta to a delta-tail configuration, which made it lighter and more agile. But the contest did not allow Boeing enough time to finish that design.

I wonder if the delta-tail design would have addressed the vtol concerns that Richard pointed out earlier

 

[Mike OTDP]

At the same time, I've also read that it was the Navy, whose last minute requirement changes, is what screwed over the Boeing X-32 entry.
the Navy wanted more agility and a lighter air frame at the last minute. So Boeing had to change their design from a pure delta to a delta-tail configuration, which made it lighter and more agile. But the contest did not allow Boeing enough time to finish that design.

You have to remember that the three services had very different needs. The USAF wanted an F-16 sprinkled with Tarnhelm filings, to make it stealthy. The USMC wanted an F-18 sprinkled with pixie dust, to make it STOVL. The Navy wanted a high-end strike fighter...but was told to shut up and take whatever the Air Force and Marines came up with.

 

[gtg947h]

The lift jet solution was not popular because it couldn't do the job! The X-32B's VTOL performance was so marginal that it couldn't perform at Edward's hot and high location so they had to take it across the country to PAX River at sea level to have dense enough air for the engine to have enough performance to lift the B with many parts stripped off to save enough weight just to get off the ground vertically.

I think the “lift jet” being referred to earlier was another proposal (McDD?) that actually had a Soviet-style lift jet (a small separate engine in about the same place as the F-35 lift fan). I think that one lost out due to temperature concerns or something.

But I’d agree, the X-32 was doomed by its STOVL performance. The lift fan was a high risk/high reward calculated gamble by Lockheed, and it paid off.


Ah, found a reference: https://www.flightglobal.com/mdc-to-pick-jast-lift-engine/15444.article

 

[Archibald]

I think the “lift jet” being referred to earlier was another proposal (McDD?) that actually had a Soviet-style lift jet (a small separate engine in about the same place as the F-35 lift fan). I think that one lost out due to temperature concerns or something.

Yes, my point exactly. There were three JSF proposals: the Lockheed one that won, the ugly Boeing that reached prototype level, and a third one by MDD-BAe that was killed at paper level.

That last one started with a lift-fan like the F-35, except driven by engine hot gases (XV-5A style) rather than Bevilacqua smart trick of a shaft.

Could have been an interesting alternative to the F-35 being rather similar and unlike the Boeing one, a clean break from the Harrier.

Alas, MDD was unable to make this system work and they replaced their fan with a Yak freestyle pair of lift jets. In turn, this set the project back by 20 years, to Convair 200 and this was unacceptable to JSF, and thus MDD was kicked out.

 

[uk 75]

It is interesting that the UK spent a long time in the 70s trying to combine its Jaguar and Harrier replacement aircraft into one design.
Eventually we gave up and the long path to the CTOL Typhoon began.
I wonder what would have happened if the USAF and USN had insisted on a CTOL only design and told the Marines to buy it to replace their F18s and quietly walk away from.VSTOL.
I suspect the result would have been a world beater like the F4.

 

[Archibald]

There are many interesting "branchings" past 1969 and Harrier Mk.1 IOC with the RAF.
- Convair 200 in place of Rockwell XFV-12 circa 1972
- AV-16, same time, same place, 1972 or later, it died only circa 1975
- Big Wing Harrier / Sea Harrier and no AV-8B (1975-1977)
- Hawker P.1216 for DARPA ASTOVL circa 1983 (and no F-35 down the road)

 

[red admiral]

LM played a blinder on X-35 by making a subscale aeroplane without things like weapon bays, and putting a full scale engine in it. No wonder it's STOVL performance was good.

This doesn't mean that X-32 was a better answer though.

Or that Shaft Driven Lift Fan is the best answer. The best answer depends on the requirements set. By having limited kinematic performance requirements lift fan is a better answer than direct lift, but if these requirements were higher then direct lift would be competitive, as it is the higher fall out kinematic performance doesn't earn any benefit.

Still, it's pretty unclear that you can get a good configuration design with direct lift, fully convoluted intakes, and large internal weapon bays. Everything is a trade off.

 

[BLACK_MAMBA]

The lift jet solution was not popular because it couldn't do the job! The X-32B's VTOL performance was so marginal that it couldn't perform at Edward's hot and high location so they had to take it across the country to PAX River at sea level to have dense enough air for the engine to have enough performance to lift the B with many parts stripped off to save enough weight just to get off the ground vertically. The Boeing team had people with the most VTOL jet experience in the world and wound up with an airplane that could only VTOL at sea level with parts missing. That is an indication that lift jet had reached the peak of its evolution.

It was an advantage for LM to have started with a clean sheet that made them look at the problems of lift jet and solve those along with looking at new ways to increase VTOL performance beyond what the Harrier had done. LM's lift fan innovation improved VTOL performance by greatly increasing and cooling the air mass directed at the ground. A side benefit of the column of air drawn into the lift fan was a ram air effect into the auxiliary air intakes that increased engine performance during VTOL. This air was cool and free of exhaust gas recirculation that is a known problem of Harriers.

The X-35B with its lift fan went on to do the first VTOL supersonic flight. The X-32B could barely get off the ground.

Others have already mentioned the intended production design from Boeing was going to have a lighter structure than the prototype. It should also be mentioned Boeing gambled on an advanced material (the name of which I can't recall) to build the wing essentially with a single skin. This failed so they had to make use of more conventional but heavier methods.

A lot of things went against Boeing at a very late stage in prototype maturity. Maybe that just indicates how far they were pushing their direct lift concept with only a small performance margin? Regardless I do believe they were not idiots and would not have persued the concept they did if they didn't believe it could work.

 

[Archibald]

Everything is a trade off.

Seconded. Even more with VSTOL - one could even say: everything is a compromise (if not compromised).

 

[asVAL]

Was using the F119 a requirement in the JSF selection? The X-32 imo was massively constrained by using the F119 for powering the bleed air nozzles. Looking at the Harrier which had the front nozzles diverting air from the frontmost fan which meant they had alot of cool air going out of that nozzle. Versus the X-32 which had to deal with hot,low density air from a very turbojet-y F119 which translates to

• Not enough lifting power (hence why the engineers had to remove stuff, like the part of the intake that would've dealth with preventing hot air ingestion)
• Hot air ingestion, see above.

The Harrier OTOH had a compact high-bypass Pegasus that could generate alot of not-as-hot air. And the X-32 had no water injection system but improved turbine techs could've compensated.

If the Boeing engineers had cheated with a, let's say, down scaled F108 or some sort of reheated regional jet turbine (F130 etc). This engine could also be fitted to the A-10 and B-52 fleet granting more commontionality plus the already genius monolithic composite wing.

 

[Richard N]

LM's shaft driven fan solved the hot gas ingestion problem and provided extra cool ram air flow into the engine while the aircraft was performing VTOL. It is unlikely any non-shaft driven fan design could provide those benefits.

Another benefit of LM's shaft driven fan was the possibility of using the shaft drive to run a generator as a high voltage power source for future energy weapons or avionics.

 

[asVAL]

LM's shaft driven fan solved the hot gas ingestion problem

Did they had one in the first place?

and provided extra cool ram air flow into the engine while the aircraft was performing VTOL. It is unlikely any non-shaft driven fan design could provide those benefits.

Given that a fan is a fan a GDLF could provide the same benefits. It didn't work though so SDLF won.

Another benefit of LM's shaft driven fan was the possibility of using the shaft drive to run a generator as a high voltage power source for future energy weapons or avionics.

My understanding is that they would've switched out the lift fan module for a laser turret and use the powered shaft to generate electricity.

However Boeing's tailless delta does have some advantages of its own. Namely the advanced construction. With the notional engine I proposes would be another. But don't mistake that for me advocating for the F-32. I'm more of a lift jet guy.

 

[_Del_]

The lift jet solution was not popular because it couldn't do the job! The X-32B's VTOL performance was so marginal that it couldn't perform at Edward's hot and high location so they had to take it across the country to PAX River at sea level to have dense enough air for the engine to have enough performance to lift the B with many parts stripped off to save enough weight just to get off the ground vertically.

Most all of this is true, but the framing is doing a heavy job holding up your conclusions.
You could as easily disingenuously frame LockMart's effort as being unable to build a working demonstrator with structural space and weight required for an internal weapon bay.
And as many noticed at the time, running behind seemed to work in LM's favour when the design requirements changed late and Boeing was locked in.

I'm not convinced Boeing would have done a better job managing the program, but they would have been hard pressed to do much worse, as it turned out.

 

[donnage99]

One likely outcome I think people can agree on is that if x-35 wasn't chosen we would have more f-22 because of..... politics

 

[Desertfox]

In a world where you end up with 3 completely different air-frames sharing the same engine and avionics, and say the USAF goes with McD, USMC goes with LM, what does the Navy do? What design is closest to what the Navy wanted?

 

[red admiral]

LM's shaft driven fan solved the hot gas ingestion problem and provided extra cool ram air flow into the engine while the aircraft was performing VTOL. It is unlikely any non-shaft driven fan design could provide those benefits.

Its also a function of the other requirements e.g. if the manoeuvre/acceleration requirements for fighter combat were more stressing then the main SDLF benefit disappears because you need higher thrust/weight in combat condition and hence a larger engine, and that higher thrust/weight gets you closer to the hover requirement.

One advantage of X-32's direct lift approach was much higher combat T/W - hence easily exceeding the original combat performance requirements. But this additional performance wasn't valued.

The answer isn't an absolute SDLF is "better", it was simply a "better" fit for the JSF requirement.

 

[asVAL]

The key issue is that Boeing had to use an unsuitable engine. Harrier style direct lift means the engine has to supply a lot of cool air. With the Harrier the engineers combined a high bypass turbofan with water injection to increase mass output. Whereas the F119 and even the later F135 while powerful in its own rights could not compare because of the different operating features. A different engine more attuned to providing the direct lift system with cool air... Or design the airframe with a third bypass stream with some bleed air routed from the F119 all feeding mid-body tilting nozzles.

 

[GTX]

Was using the F119 a requirement in the JSF selection?

I don’t believe so. Remember that there was also the GE/RR F136 alongside the P&W F135

 

[GTX]

One thing I would say against the overall thread topic is that if the X-32 was selected as the basis for the JSF, there would still be a group of enthusiasts today complaining that the X-35 should have been chosen with comments along the lines of “ Lockheed should have been selected…look at their U-2, SR-71, F-22….blah, blah, blah…”

 

[Colonial-Marine]

The key issue is that Boeing had to use an unsuitable engine. Harrier style direct lift means the engine has to supply a lot of cool air. With the Harrier the engineers combined a high bypass turbofan with water injection to increase mass output. Whereas the F119 and even the later F135 while powerful in its own rights could not compare because of the different operating features. A different engine more attuned to providing the direct lift system with cool air... Or design the airframe with a third bypass stream with some bleed air routed from the F119 all feeding mid-body tilting nozzles.

Can such an engine hope to allow for the desired speed? There was a lot of interest in plenum chamber burning to make a supersonic Harrier variant, but I'd have to assume it was something of a dead-end since there seemed to have been a loss of interest in the idea as further work was done in ASTOVL and other programs.

I rather think the JSF requirements were simply too much for the direct lift method to provide enough thrust for. You could probably have gotten many of the requirements, but not all of them. You might have to give up VLO stealth and internal weapons carriage, or supersonic performance. Boeing probably did the best they could do with the design all things considered. But it simply wasn't enough and the compromises necessary were much more readily visible.

In terms of basic design outside of STOVL capability I think the McDonnell Douglas/Northrop/BAE design might have been excellent. With the lift jet it could probably do STOVL, but it seems like the USMC (and maybe other potential operators) were very much against the idea of such a separate lift jet. The shaft-driven lift fan was seen as less of difficult to support logistically and better in ways like reducing heat and gas ingestion. Even so preparations need to be made to concrete or ship decking to avoid damage through continuous operation because the F135 is hot and powerful. With an actual lift jet instead of lift fan, the problem would be worse.

What was the reason the gas-driven lift fan didn't work out? I know the prospect of battle damage was a concern but technically wasn't it just not working well enough for some reason?

 

[red admiral]

I don’t believe so. Remember that there was also the GE/RR F136 alongside the P&W F135

Pretty sure the engine was mandated and provided as a separate GFX item even back for X-32/35

 

[Colonial-Marine]

I believe for the demonstration phase use of a modified F119 was indeed mandated. I think there was a general understanding that the engine used by the JSF would be based off the F119, at an early stage it was still considered a variant versus a 'new' engine. The GE F136 was more about having an alternative for industrial considerations. I'm sure GE would say there are all sorts of differences making their engine better, but in practical terms I don't think the pilot would notice any difference. It would probably be even less than what you get if you compare a Block 50 F-16 with a Block 52. The difference between the F135 and say the GE XA100 or P&W XA101 is something much more significant.

I'm not convinced cancelling the F136 was a mistake, but I feel like not going forward with the XA100/101 might be one when you consider the purported improvements and the long career the F-35 will inevitably have based on how long the prior generation of fighters has served.

 

[stever_sl]

From someone who worked on both the MDC/Northrop/BAe JAST and then the Boeing JSF: Their JAST design was doomed from the outset when despite all logic, program management let Northrop decide on the propulsion system concept for VTOL even though only MDC and BAe had actual real-world experience to draw on, and Northrop picked the lift engine. The Marines tried repeatedly to get management to rethink that, saying that they wouldn't buy a multiengine STOVL, but the team's response was to keep doubling down and doing more analyses to "prove" to them that a lift engine gave the lightest, lowest-risk, least-expensive solution. Which it might have done, but that was irrelevant since the prime customer had said that they wouldn't consider such a concept in the first place. So that downselect eliminated their slick-looking offering, MDC got bought by Boeing ("a merger of equals" as they tried to call it) and then came Seattle's idea of a STOVL aircraft. Seattle had never made a jet fighter/attack aircraft before and refused to take much input from MDC people who had. The common refrain was "if you know so much, why did we win a contract for JAST and you didn't?" Their basic design was unworkable, mostly for carrier landing reasons, and it took many months of wasted effort (and $$$) before they grudgingly admitted that a horizontal tail was going to be necessary. That added a disturbing amount of weight, and the basic engine ended up being stretched as far as it possibly could be, but a gap was still left in the amount of thrust that could be gotten for hovering and pure VTOL. A small team of experienced STOVL people was formed in St Louis, and its members were told that the existence of the team wasn't being announced; if anyone found out and asked us about it, we weren't to lie, but we weren't to do any more than confirm that the team existed. The purpose was to find a way to get the excess weight out of the aircraft. It turned out that there was a way, by using a different exhaust nozzle design. That information was then presented to Seattle program mangement and they refused to consider it. Instead, they came up with what they called "lift thrust augmentors" or LTAs, which were little downward-pointing engines in the center body to be used only to add vertical thrust when needed. The customer, having made their abhorrence for multiple VTOL-mode engines crystal clear during JAST, didn't want to have anything to do with LTAs, and so despite many areas of competitive advantage over Lockheed's design, the Boeing design wasn't selected, or so our people were told at the post-award evaluation and scoring briefing. And that's the long and short of it. If MDC and BAe had overruled the lift engine for JAST in favor of a shaft-driven lift fan that was in the initial work for the ASTOVL program, in all likelihood it would have been a dual contract award for Lockheed and MDC with no need to bring in Boeing. If Seattle had accepted the nozzle design mods that the St Louis team came up with, there would have been no need for LTAs and it's interesting to speculate on how JSF would have been decided.

 

[Yellow Palace]

If MDC and BAe had overruled the lift engine for JAST in favor of a shaft-driven lift fan that was in the initial work for the ASTOVL program, in all likelihood it would have been a dual contract award for Lockheed and MDC with no need to bring in Boeing

It's mentioned in one of the JSF threads on here that the original idea for the X-32 programme was to fly a couple of prototype ASTOVL systems. LM had the shaft driven fan, MDD had a gas driven fan, and I think someone else had a third candidate system. The idea was that after testing, there'd be a competitive design phase for a production aircraft (CALF?) using the preferred system.

But when it turned into JAST, LM had exclusivity on the shaft driven fan, and the gas driven fan didn't work. Which left lift engines or vectored thrust for Boeing and MDD/Northrop/BAe to pick from. And as it turned out, the shaft driven fan was a better fit to the requirement.

 

[red admiral]

But when it turned into JAST, LM had exclusivity on the shaft driven fan, and the gas driven fan didn't work.

JSF source selection was effectively fixed from the early 90s DARPA ASTOVL award of SDLF to Lockheed. Everything after is just in the noise really.

 

[Scott Kenny]

It is interesting that the UK spent a long time in the 70s trying to combine its Jaguar and Harrier replacement aircraft into one design.
Eventually we gave up and the long path to the CTOL Typhoon began.
I wonder what would have happened if the USAF and USN had insisted on a CTOL only design and told the Marines to buy it to replace their F18s and quietly walk away from.VSTOL.
I suspect the result would have been a world beater like the F4.

Marines would tell USAF to go piss up a rope, and would tell Navy that means Navy needs to attach a carrier group to the amphib group for air support. Navy would quickly come around and tell USAF to go piss up a rope, Marines require VSTOL.

Once the USMC got Harriers, both USMC and USN were sold on the idea of being able to stick half a squadron of planes onto an LHA and let the carriers go be someplace else.

Still, it's pretty unclear that you can get a good configuration design with direct lift, fully convoluted intakes, and large internal weapon bays. Everything is a trade off.

I don't think you can. A direct lift engine and weapons bays are both competing for volume at the CG. At best you'd be looking at an airframe like the P1214/P1216 with the weapons bays in the front of the booms.

 

[Hood]

If YF-22 and X-32 had won, imagine how different and cool all the stealth clones around the world would look today.

 

[asVAL]

Can such an engine hope to allow for the desired speed? There was a lot of interest in plenum chamber burning to make a supersonic Harrier variant, but I'd have to assume it was something of a dead-end since there seemed to have been a loss of interest in the idea as further work was done in ASTOVL and other programs.

Well I think yes. PCB seems to be a solution for direct lift supersonic VSTOL but seems overly complex comparing to SDLF. To clarify, the engine I proposed would be something like a F119 with a smaller core, and higher bypass ratio. So there's a lot of cold air through the bypass duct that would be expelled downward for VSTOL flight and in level flight they would provide cooling, reaction control or just shat straight out of the tailpipe. It's a trade of exhaust velocity (colder air in the burner) for VSTOL thrust. Maybe the old delta would've helped.

What was the reason the gas-driven lift fan didn't work out? I know the prospect of battle damage was a concern but technically wasn't it just not working well enough for some reason?

Well from what I've read on this excellent forum there were some issues namely low reaction speed to throttle change and the weight and size penalty of the air routing. SDLF which is literally just a transfer shaft worked better.

 

[Scott Kenny]

Well I think yes. PCB seems to be a solution for direct lift supersonic VSTOL but seems overly complex comparing to SDLF. To clarify, the engine I proposed would be something like a F119 with a smaller core, and higher bypass ratio. So there's a lot of cold air through the bypass duct that would be expelled downward for VSTOL flight and in level flight they would provide cooling, reaction control or just shat straight out of the tailpipe. It's a trade of exhaust velocity (colder air in the burner) for VSTOL thrust.

Disagree that PCB is overly complex. The shaft driven lift fan requires a clutch and gearbox capable of handling 40,000hp.

While the challenge with PCB is the flame holders in the curves of the plenum chamber.

 

[MadRat]

I never liked winner takes all. F-32 proceeds minus EODAS and EOTS? I think that is a terrible idea. JSF needed to key in subsystems separate from the base airframe to make this alternative feasible. NG simply had a much better big picture design irregardless their airframe choice literally looks nothing like X-35. Same issue with the ATF winner, the F-23 would have been a simpler design to build and maintain, but NG won the competition on the overall big picture design. F-23 with MAW, 2D tvr, and the bombbay innovations that were in F-22 would have not been possible in the winner takes all outcome.

F-32 only makes sense if you scrap F-32B and allow NG to proceed with F-35B as the -B winner and as a competitor against F-32C for future orders. That way USAF and USN end up with F-32A and F-32C, but USMC is able to choose its own JSF offshoot. F-32B was simply a loser by design. It had no chance. But F-32A and F-32C really needed the goodies found in the F-35 program to justify their existence. I know everyone loves supercarriers, but the USN really would have benefitted from distributed airpower in cruisers with STOVL and expanded helicopter hangar packages. Losing a supercarrier is basically losing $100 billion in one swoop, whereas hybrid cruiser carriers would probably be 1/10th of that. The biggest difference is no longer treating carriers as mobile islands for extended operations. That required relinquishing prolonged bombing campaigns to the USAF and a reduced number of supercarriers. Not sure we still aren't headed that route as both supercarriers and LHDs are ill equipped to fight future drone wars.