Advanced Harrier Projects

[Boomerang503]

Proposed. PCB and a 33,000+ Pegasus. No hardware.

A model at most.

 

[stever_sl]

Not finding one in a quick search, what I am remembering was a harrier with "saggy tits" for the PCB nozzles with US markings on it. I'm assuming it was a singular test or demonstration type.

PCB nozzles on this were located much lower on the airframe than the cold nozzles. Where the standard Harrier cold nozzles are up in the "wingpits", the PCB nozzles were rotated down to about 30-45deg below horizontal axis of the engine/airframe, well clear of the wings and fuselage sides.

I'm very familiar with the P.1154 design with PCB, and that's why we needed an alternative for Harrier 21, just too much cross-sectional area in the middle of the aircraft causing unmanageable transonic drag rise, and no way to reduce the area there. About that AV-8C, I do know of an AV-8B that was modified with wingtip AIM-9s and zero-scarf rear (hot) nozzles, but that was a bit after I'd moved on from the group. I think the one you're referencing was a Harrier GR.1, XV798, that did some PCB work and is in the museum at Kemble now, with those nozzles still installed as far as I know.

 

[Zoo Tycoon]

I'm very familiar with the P.1154 design with PCB, and that's why we needed an alternative for Harrier 21, just too much cross-sectional area in the middle of the aircraft causing unmanageable transonic drag rise, and no way to reduce the area there. About that AV-8C, I do know of an AV-8B that was modified with wingtip AIM-9s and zero-scarf rear (hot) nozzles, but that was a bit after I'd moved on from the group. I think the one you're referencing was a Harrier GR.1, XV798, that did some PCB work and is in the museum at Kemble now, with those nozzles still installed as far as I know.

About Oct 1987 I was a member the Tandem fan team at RR Patchway. There were three other teams working simultaneously on;- PCB, Remote Augmented Lift (RALS), and ejector lift. I remember there were quite open concept comparative reviews every few months. At one of these, PCB got absolutely hammered on safety grounds, principally the critical need to maintain stable combustion in multiple places within the engine. Statistics were presented on existing engine afterburner light up reliability with the inference that given a failure for just one zone to light, would be loss of aircraft (Catastrophic). This was so bad it implied an unsustainable fleet. Although it was presented as requirement for improvement, many said anything up to a couple of years later, that it was a factor in the PCB rejection. I certainly concur that it was also said that it was not well suited to a supersonic aircraft architecture, ground erosion and hot gas recirculation.

During my time at RR , RALS was bleed air driven. Tandem fan expired in about 1990, ejector lift a bit earlier. The step change occurred quite quickly when RALS (shaft) was studied which killed off PCB once and for all.

 

[Mike Pryce]

About Oct 1987 I was a member the Tandem fan team at RR Patchway. There were three other teams working simultaneously on;- PCB, Remote Augmented Lift (RALS), and ejector lift. I remember there were quite open concept comparative reviews every few months. At one of these, PCB got absolutely hammered on safety grounds, principally the critical need to maintain stable combustion in multiple places within the engine. Statistics were presented on existing engine afterburner light up reliability with the inference that given a failure for just one zone to light, would be loss of aircraft (Catastrophic). This was so bad it implied an unsustainable fleet. Although it was presented as requirement for improvement, many said anything up to a couple of years later, that it was a factor in the PCB rejection. I certainly concur that it was also said that it was not well suited for supersonic flight aircraft architecture, ground erosion and hot gas recirculation.

During my time at RR , RALS was bleed air driven. Tandem fan expired in about 1990, ejector lift a bit earlier. The step change occurred quite quickly when RALS (shaft) was studied which killed off PCB once and for all.

Was that due to the newer PCB 'swirl' burners in place of the colanders? Ian Clapham and others did a lot to make the colanders work on the PCB Harrier rig and NGTE seemed happy in the end.

There was also a tandem fan variant with PCB for the BAe P1222. Know any more?

 

[Zoo Tycoon]

Was that due to the newer PCB 'swirl' burners in place of the colanders? Ian Clapham and others did a lot to make the colanders work on the PCB Harrier rig and NGTE seemed happy in the end.

There was also a tandem fan variant with PCB for the BAe P1222. Know any more?

All the Tandem fan work we did was cold front nozzle aimed at pre JAST studies. I briefly saw several aircraft concept architecture but can’t recall the designation… details of these were shared sparingly with the engine team especially the more junior members.

Whilst I was aware of quite an activity on PCB combustion it wasn’t my specialty on the project so didn’t pick much detail. Two years previously I briefly worked in the combustion technology group but so long ago I can’t recall a single name. There wasn’t any PCB work going on at that time in that group ;- we were trying to figure out why “Larrbruch Carbon” was burning out RB199 vaporisers.

 

[stever_sl]

Was this an actual demonstrator or a proposed demonstrator?

A GR.1 demonstrator was actually built and flown, nothing on the US side though, beyond the artwork and model.

Looks like a brute-force way of puhing a first generation Harrier through the sound barrier. Basic issue was the Pegasus big fan needed big round intakes not exactly adapted to supersonic flight. This project desperately tries to go around this major issue. Was it realistic ? no idea. There are good reasons the P.1154 and P.1216 no longer looked like Harriers...

I was being a pest in the Advanced AV-8 and V/STOL Group at the time, pushing for supersonic performance while literally everyone else was "proving" to me that a fighter could and should be subsonic, which just shows how deeply ingrained the Harrier's limitations had become in people's minds. In the end, to shut me up, the head of our Aero group did a whole series of performance calculations based on the AV-8B's geometry, ignoring the extra mess that PCB nozzles would create with cross-sectional area at the mid-fuselage, and arbitrarily adding more and more thrust. In other words, all the benefits of PCB without any of the liabilities. He proved that you could double and even triple the thrust but the basic airframe was so pudgy that you just couldn't break through the transonic drag rise. You'd need a much thinner wing and narrower fuselage to have any chance at all. The AV-8B's supercritical wing had become its major advantage (it's hard to remember those days) because it was all-composite, rare back then. Thinning it down would take away volume from its integral fuel tank, while adding PCB or any other form of afterburning would suggest that you needed more fuel, not less. The so-called "Big Wing" variant had been looked at in the UK as well as in St Louis and while it might have gained back the tank volume, it was too wide to be compatible with LPH/LHA/LHD elevators and hangar deck spaces, without adding the weight and complexity (and potential loss of fuel volume again) of a wingfold system. So there wasn't going to be any PCB-equipped Harrier variant, but then Rolls Royce came up with a repackaged Pegasus engine core that changed everything about the mid-fuselage geometry, and we were off on what became the Harrier 21.

 

[stever_sl]

This looks to be the Model 4629 (as I recall it) which was what the Model 279-3 allegedly evolved into, although in fact the latter was just abandoned. I remember being amused at the traditional "evolution tree" that the ASTOVL group had put together, with top view sketches showing how the Model 279 had been gradually modified and refined in minor ways until suddenly the completely different 4629 was just tacked on at the end. The message I got was "we spent a lot of time and money trying to make the canard/delta configuration work, then realized that a traditional wing/tail design was better, so that's what we have now, at the last minute and representing relatively minimal analysis and risk reduction." Somewhere I have a photo of part of the ASTOVL engineering and design team in St Louis sitting around our big conference table. I'll see if I can find it, it has a painting of that airplane on an easel behind us.

I looked everywhere but couldn't find that photo, then today, out of the clear blue, a former coworker sent me an email and attached that exact photo to it. The resolution isn't great here, but this is the photo of our ASTOVL study team at one moment in time, with the Model 4629 on the easel. I'm the 3rd standing guy to the right of the painting, the one with the beard. 37 years ago - good heavens!

 

[Mike Pryce]

Great photo. Thanks for sharing. How long had the 4629 design been going by that point? I know in 86 the UK-UK study from St Louis was expected to be the 279-3, at least on this side of the pond. There was some dismay at the 4629 being counted as vectored thrust with it's 'cactus' layout.

 

[Archibald]

Amazing memories. This forum membership is getting more and more awesome with each passing day.

 

[stever_sl]

Great photo. Thanks for sharing. How long had the 4629 design been going by that point? I know in 86 the UK-UK study from St Louis was expected to be the 279-3, at least on this side of the pond. There was some dismay at the 4629 being counted as vectored thrust with it's 'cactus' layout.

At the time when 279-3 was about to be junked and replaced with 4629, I was still on the Advanced AV-8 and V/STOL team, working with Harrier 21, so I don't know all the issues involved with early incarnations of ASTOVL. Once MDC's corporate geniuses decided to halt H21 in favor of ASTOVL, not knowing that the latter was nothing more than a cover program for behind-the-scenes work between DARPA and Lockheed on the shaft-driven lift fan technologies, I migrated over to ASTOVL myself and worked in their Systems Engineering section on Risk Management. By then the configuration had definitely changed.

 

[Zoo Tycoon]

At the time when 279-3 was about to be junked and replaced with 4629, I was still on the Advanced AV-8 and V/STOL team, working with Harrier 21, so I don't know all the issues involved with early incarnations of ASTOVL. Once MDC's corporate geniuses decided to halt H21 in favor of ASTOVL, not knowing that the latter was nothing more than a cover program for behind-the-scenes work between DARPA and Lockheed on the shaft-driven lift fan technologies, I migrated over to ASTOVL myself and worked in their Systems Engineering section on Risk Management. By then the configuration had definitely changed.

Hi Steve
Where did the shaft driven lift fan (RALS to us) originally come from? In the RR engine trade study at Patchway we were very much focused on bleed air powered lift fans;- there quite a few drawn up with coaxial turbines, tip turbines, geared turbines etc. I remember the shaft concept just appearing, taking centre stage and dominating very quickly. It was just about the time that I left RR for my next adventure. Years later a colleague from that time mentioned the break through was the realisation that carbon wheel brake technology could be used in a clutch which could attenuate the power off take.

Please tell more…