Advanced Harrier Projects

Martes said:
I actually found something along these lines. Mind - it's from a computer game and absolutely fictional, but - it shows how to combine the 4-exhaust layout with internal weapons bay. (sorry for the nuclear blast in the background, that's the only coherent bottom view I could find)

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You just need two engines, and put the bay between them.
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The problem always was that the USMC was adamant about never buying a STOVL fighter/attack airplane that had to have more than one working engine to hover and land safely. Now, of course, they have F-35B, whose lift fan is a lot more complex than people seem to realize. I would love to see the reliability and safety figures on that, as opposed to those for an outright 2-engine design, remembering that it's not just the lift fan itself but the driveshaft and clutch and gearbox whose failure would also lead to catastrophe just as surely as failures in the actual engine. 1739299509175.png
 
FighterJock said:
Always wondered where Boeing got their idea for the JSF design from. Now I know.
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If you mean X-32, several people in Seattle (including Dennis Muilenburg, future CEO of Boeing) patented the configuration and some of us speculated that this patent was the reason they held on to the ugly and unworkable delta-with-backward-inlet layout for so long. That might not be fair, but being able to say that "I thought up that airplane" is a powerful motivator. (We ran into the same kind of thing on another failed program that had a foundational patent with fatal flaws, but that's a whole other story.) 1739300283073.png
 
Scott Kenny said:
Probably not. The forward nozzles would be in the way of significant blending there. At best, it'd probably be as blended as the XP-67 Moonbat.
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Scott Kenny said:
Probably not. The forward nozzles would be in the way of significant blending there. At best, it'd probably be as blended as the XP-67 Moonbat.


LOL. Sure does!
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And if you want to know all about XP-67, you can read the book that my wife and I wrote on it! Only I'd suggest the e-reader edition rather than a paper copy. On the paper copy the photos and drawings and blueprints are way smaller than we thought they'd be, due to how the publisher arranged the material to fit the format of this general series (which has now been discontinued, by the way.) With the digital edition, though, you can open each illustration and zoom in to get much better detail. Oh, and by the way, we don't get a penny in royalties, it was strictly a work for hire. :)

https://www.ospreypublishing.com/us/mcdonnell-xp67-moonbat-9781472853035/
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stever_sl said:
patented the configuration and some of us speculated that this patent was the reason they held on to the ugly and unworkable delta-with-backward-inlet layout for so long.
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Funny, I always liked this configuration of early X-32. No idea how it flew, but it looks cute :)

What's that marked by 53 there? Looks like rotating exhaust.
 
martinbayer said:
I don't think either of them was (ex) Navy, and as for inhaling, apart from pure ambient air, any other matter is pretty much never a good idea...
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Yes, but there are always accidents of some poor Sailor standing up too close to the inlets and getting taken for a ride.

If the sailor is lucky they drop a flashlight or their helmet comes loose and takes out the engine before they get to the fan. But now that I think about it, the Radar Blocker grid in the X-32's mouth would hopefully stop the sailor from going into the fan.
 
Scott Kenny said:
Yes, but there are always accidents of some poor Sailor standing up too close to the inlets and getting taken for a ride.

If the sailor is lucky they drop a flashlight or their helmet comes loose and takes out the engine before they get to the fan. But now that I think about it, the Radar Blocker grid in the X-32's mouth would hopefully stop the sailor from going into the fan.
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I *honestly* did not have that aspect in mind, but well, then let's consider grids in front of engine air intakes for *every* design (civilian, commercial, military, experimental, whatever) going forward due to FOD risk. I have no skin in this game, so I'm genuinely curious where this discussion might go, but then again, I realize this is definitely off topic, so please, moderators, deal with the mess I just made as you see fit.
 
martinbayer said:
I don't think either of them was (ex) Navy, and as for inhaling, apart from pure ambient air, any other matter is pretty much never a good idea...
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"But ... but... what I'm gonna do in a submarine, with sea men everywhere ?" - The Village People
 
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Martes said:
Funny, I always liked this configuration of early X-32. No idea how it flew, but it looks cute :)

What's that marked by 53 there? Looks like rotating exhaust.
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Yes, 53 is the forward ("cold" flow) vectorable nozzle on each side of the fuselage. And it apparently flew very well despite its appearance, according to the test pilots. I never saw the Government's official comparison though.
 
Archibald said:
I always felt P.1216 was the logical end of P.1154 developments.
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There was this image around the thread (I can't find the exact post, but I certainly downloaded it from somewhere around here):
That shows (probably) the most "modern" configuration of the aircraft with this engine. I suppose the weapon bays are located a bit after the secondary nozzles and open (mostly) sideways. Could it work at all? Would they have to be extended? Especially with what you say about PCB temperatures? Is it landing gear in those tail consoles? Or fuel? And what is known about this image, was it just a Rolls Royce illustration, or one of existing concepts?
 

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Martes said:
There was this image around the thread (I can't find the exact post, but I certainly downloaded it from somewhere around here):

That shows (probably) the most "modern" configuration of the aircraft with this engine. I suppose the weapon bays are located a bit after the secondary nozzles and open (mostly) sideways. Could it work at all? Would they have to be extended? Especially with what you say about PCB temperatures? Is it landing gear in those tail consoles? Or fuel? And what is known about this image, was it just a Rolls Royce illustration, or one of existing concepts?
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No, the weapon bays would need to be out of the PCB flow. It might work if the bays were between the canards and the main.
 

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Archibald said:
Wait, is that a variant or an evolution of P.1216 ?
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It is not related at all. Just PR artwork to show three nozzles by Rolls, with pods in just the right place to be burned off, the very thing the P1216 was to avoid. It's a shame Frank Mason put it in his Hawker Putnam. Complete mistake.
 
Ok thanks. I see the point. After the three nozzles breakthrough, there were good reasons why the rear fuselage was split into twin booms, away from the PCB nozzle in the middle.
 
zen said:
I always felt this would make better CTOL design than a STOVL one.
Which is to say a single fixed nozzle out the back, rather than the three poster vectored nozzles.
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Straight-through Pegasus would have been roughly 28-30klbs of thrust at military power. Then you can stick an afterburner on it and kick it up to probably 55klbs.
 
Scott Kenny said:
Straight-through Pegasus would have been roughly 28-30klbs of thrust at military power. Then you can stick an afterburner on it and kick it up to probably 55klbs.
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More like 45. F135 is 28/45; a multiple of 1.5-1.6 for afterburner is pretty standard and 55 would be close to double.
 
An example straight through Pegasus is RB.431 with ~16klbf dry and 28klbf wet. A later Pegasus variant probably higher thrust with greater mass flow and turbine and reheat temperatures.

RB.431 was a physically big engine, but relatively cheap as there wasn't that much "advanced" technology in it compared to the likes of RB 199 derivatives.

Reheat thrust augmentation ratio depends on bypass ratio. Higher BPR means higher augmentation in reheat. So ~1.8x for RB.199 and RB.431 with higher BPRs than traditional fighter engines
 
red admiral said:
An example straight through Pegasus is RB.431 with ~16klbf dry and 28klbf wet. A later Pegasus variant probably higher thrust with greater mass flow and turbine and reheat temperatures.
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Reduced size, surely.

Pegasus Mk107 is pushing 23,500lbs thrust, with the bends in the gas flow. So removing the bends alone should get you up to 28-30klbs. Yes, a thrust multiplier of 1.96 to get to 55klbs from 28 is high, but not unreasonable when 60% of the airflow comes out the cold nozzles (I'm struggling to find a bypass ratio given).
 
Scott Kenny said:
Reduced size, surely.
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Earlier Pegasus variant than Mk 107, but mostly the thrust increases in VTOL don't translate to a typical max dry rating e.g. overspeeding the fan, water injection. A more typical max dry rating for the later Pegasus is still around 16klbf for Up and Away flight.

If 60% of the flow comes from the cold nozzles then BPR = 0.6 / (1-0.6) = 1.5

The bends in the exhausts don't make a large impact to efficiency/thrust as the pressure gradient is favourable here (+vanes). Whereas bends on the intake side have a much larger impact on efficiency.
 
Martes said:
Funny, I always liked this configuration of early X-32. No idea how it flew, but it looks cute :)
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stever_sl said:
And it apparently flew very well despite its appearance, according to the test pilots. I never saw the Government's official comparison though.
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The USN differed there, as their evaluation said the delta-design wouldn't do well in the turbulent air at the aft end of the flight deck (same thing that helped end the A-12 program).

That is why Boeing proposed the "lengthened aft fuselage with horizontal stabilizers added" version shortly before Lockheed was granted the win.
 
BlackBat242 said:
The USN differed there, as their evaluation said the delta-design wouldn't do well in the turbulent air at the aft end of the flight deck (same thing that helped end the A-12 program).

That is why Boeing proposed the "lengthened aft fuselage with horizontal stabilizers added" version shortly before Lockheed was granted the win.
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The aft fuselage was lengthened and horizontal tails added well before the competition downselect. It was the configuration that we did performance analysis on, and cost, risk, signature, vulnerability, everything. I started on the program about a month after the Boeing/MDC merger and was with it all the way to the catastrophic endgame. It was really hard to get Seattle to accept the horizontal tails but it had to be done, and done relatively quickly, for the reason you mention on the Navy version, among other things. I don't know the exact date when the tails became part of the official configuration, but maybe somebody still has the program history/evolution timeline chart that was put together for one of the managers. If memory serves, the tailless delta configuration was Model 372 which changed to Model 374 once the tails were added, if that helps.
 
stever_sl said:
The aft fuselage was lengthened and horizontal tails added well before the competition downselect. It was the configuration that we did performance analysis on, and cost, risk, signature, vulnerability, everything. I started on the program about a month after the Boeing/MDC merger and was with it all the way to the catastrophic endgame. It was really hard to get Seattle to accept the horizontal tails but it had to be done, and done relatively quickly, for the reason you mention on the Navy version, among other things. I don't know the exact date when the tails became part of the official configuration, but maybe somebody still has the program history/evolution timeline chart that was put together for one of the managers. If memory serves, the tailless delta configuration was Model 372 which changed to Model 374 once the tails were added, if that helps.
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Actually this paper gives the context for a number of changes that were made, including lengthening the fuselage and adding horizontal tails. It dates the studies to 1998, and a figure implies that their incorporation became official very early in 1999. Downselect was in late 2001.
https://archive.aoe.vt.edu/mason/Mason_f/JSFBuescher.pdf
 
stever_sl said:
The aft fuselage was lengthened and horizontal tails added well before the competition downselect. It was the configuration that we did performance analysis on, and cost, risk, signature, vulnerability, everything. I started on the program about a month after the Boeing/MDC merger and was with it all the way to the catastrophic endgame. It was really hard to get Seattle to accept the horizontal tails but it had to be done, and done relatively quickly, for the reason you mention on the Navy version, among other things. I don't know the exact date when the tails became part of the official configuration, but maybe somebody still has the program history/evolution timeline chart that was put together for one of the managers. If memory serves, the tailless delta configuration was Model 372 which changed to Model 374 once the tails were added, if that helps.
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I really wish someone made a model of the "EMD" version... I still have a couple of the Italeri X-32 kits lurking around.
 
From this book.
 

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Scott Kenny said:
I really wish someone made a model of the "EMD" version... I still have a couple of the Italeri X-32 kits lurking around.
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Air Signatures did a 1/72nd scale diecast X-32A (#99138) that, while having all the drawback of metal diecast - deep panel lines, bosses for screws, etc - looks like the X-32A OML unlike the Italeri kit which is marginal even when viewed from six feet. As far as EMD, you are out of luck unless you can pick up a Pacmin solid on evilBay.
 

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