Bristol Siddeley Turbofans?

I would just like to thank everybody who has thus far taken part in this thread, everybody has raised some very interesting points and provided allot of excellent information, so thank you all very much!

(Why no turbofan for TSR.2?) Timing.

Turbojet BE.10 and (later term, turbofan) E.113 originated 1946 for (to be V-Craft). EE’s bid used their (in house) Napier engine; Avro took Bristol and won with (to be) B.Ol.100. EE/Napier sold their scheme to RR, where Griffith cared for it as RB80. Priority to 1950 went on making any Avon work. RB80 was then selected for Valiant B.2, the intended prime production version. Cancelled. Conway retained funding for V.1000(VC7), which died in 1955, but was then bid for Mk.2 Victor/Vulcan, winning one, and for DC-8/40, 707-400, VC10.

Spec for (to be)TSR.2 derives from 1957, when DH Gyron and Ol.200 had higher bench mileage than Conway. RR punted genus Medway, a turbofan of many cousins. Industry was told this would be the last big project, we had excess design capacity, kindly merge. Bristol + (HSAL) ASM were willing to do so around an even bigger B.Ol. RR looked about them, at Napier and DH, and said nah! – just take Medway. At this time BS.53 was a weird experiment. PCB had been filed away after RR acquired W.2/700 (M.52’s engine): it was resurrected for a big BS.53 in 1961, when we also decided to do the SST with France. A modest variant of B.Ol.22R justified them ceding lead to the Rosbifs; any novel type, such as a turbofan for endurance/economy, would admit SNECMA to, at least, equality.

Bit odd by then for the T-S-R type to be thrust on geriatric metallurgy/dynamics. Even odder to be defined by a steam room for valves. Hence the 1961 draft ASR built around quad/electric signalling that eventually became Tornado.

Interesting points, especially about the Avon. It was in fact technology from Armstrong-Siddeley that helped make the Avon what it was(is). Again from my own experiences and what I have read about the Conway with reheat it would have been quite a challenge to make it a reliable and stable engine.
The restrictions in service for the Victor attest to the poor working line of the lp compressor. RR did a series of strain tests in the mid eighties after which stringent operating limitations were promulgated. The Conway had always been a little too much for the intake dimensions so uprating it with the zero stage only made it worse.

Turbo Fan or Turbojet ? – If your considering the Turbine Entry Temperatures (TET) which were achieved in the 1950’s-60’s and you have a mission profile which demanded a high supersonic cruise for an extended period then you needed high mass flow, all of which is at high exhaust velocity, so your best bet is a a turbojet…….. but now you’re highly constrained to a very small design point , and if you slow down your range becomes very poor due to high fuel consumption. If you needed short term supersonic dash, transonic cruise, and long range then you need a reheated Turbofan.

Remember Concorde could supercruise at M2 without reheat, whilst TU 144 with Kuznetsov NK144 turbofan could not supercruise above M1.4 (ish). Concorde (& TSR2) just would not have achieved the M2 payload/range cruise requirements with reheated Conways. As the TET increased in the 70’s so did the achievable mass flow to exhaust velocity ratio. Hence the M2 Supercriuse turbofan became viable. However as the payload/range figures of the Concorde against the Tu144 with the Kuznetsov NK321 broadly indicate at each aircraft design point the overall efficiencies are pretty similar….. But what you gain from the Turbofan is more flexibility for lower speed range.

Any way back to the original thread. I like the story in on of the RR Heritage Trust brilliant rag “Sleeve Valve Notes” that describes an approach by NASA in the very early seventies for a version of Pegasus, without the thrust vectoring kit, as a Turbofan to power the aerodynamic proof vehicle of the Space Shuttle, what was to become the unpowered “Enterprise”.

(Why no turbofan for TSR.2?) Timing.

Turbojet BE.10 and (later term, turbofan) E.113 originated 1946 for (to be V-Craft). EE’s bid used their (in house) Napier engine; Avro took Bristol and won with (to be) B.Ol.100. EE/Napier sold their scheme to RR, where Griffith cared for it as RB80. Priority to 1950 went on making any Avon work. RB80 was then selected for Valiant B.2, the intended prime production version. Cancelled. Conway retained funding for V.1000(VC7), which died in 1955, but was then bid for Mk.2 Victor/Vulcan, winning one, and for DC-8/40, 707-400, VC10.

Spec for (to be)TSR.2 derives from 1957, when DH Gyron and Ol.200 had higher bench mileage than Conway. RR punted genus Medway, a turbofan of many cousins. Industry was told this would be the last big project, we had excess design capacity, kindly merge. Bristol + (HSAL) ASM were willing to do so around an even bigger B.Ol. RR looked about them, at Napier and DH, and said nah! – just take Medway. At this time BS.53 was a weird experiment. PCB had been filed away after RR acquired W.2/700 (M.52’s engine): it was resurrected for a big BS.53 in 1961, when we also decided to do the SST with France. A modest variant of B.Ol.22R justified them ceding lead to the Rosbifs; any novel type, such as a turbofan for endurance/economy, would admit SNECMA to, at least, equality.

Bit odd by then for the T-S-R type to be thrust on geriatric metallurgy/dynamics. Even odder to be defined by a steam room for valves. Hence the 1961 draft ASR built around quad/electric signalling that eventually became Tornado.

The Conway comes across as an engine that never quite lived up to expectations. The BS.100 was always intended for supersonic flight so it might have been a good option? An interesting side note, the BS.100 was at one time the most powerful jet engine in the western world!:eek:

The Conway was a big and powerful engine and could run virtually forever (see the East African Airways VC10s). However when they uprated it in the Victor it started to show that it had reached it’s limits unless you were prepared to rework an awful lot of the engine. I suppose in that respect it didn’t live up to expectations, it wasn’t a big seller and had few applications.

Nailed it…according to Bill Gunston’s history of Rolls-Royce engines, RR designed and built a reheat installation for a Conway in January 1959 as potential TFX engine for the US.
It was put together in a week (!) and at first gave a boost of 27.3%, rising to 47.5% a few days later.

Indeed, you are right, I’ve managed to find some info. There were a couple of proposals, one for the Republic F105 and one for the Avro(C) Arrow.
They used an Avon reheat pipe (2000 K) to lash up a test unit.
They had problems with light up and lp compressor surge, also the mixing of the air streams caused alot of trouble.I think the general idea was that there were better engines around.

Nailed it…according to Bill Gunston’s history of Rolls-Royce engines, RR designed and built a reheat installation for a Conway in January 1959 as potential TFX engine for the US.
It was put together in a week (!) and at first gave a boost of 27.3%, rising to 47.5% a few days later.

Maybe it was a case of “2nd best tomorrow”, the Olympus was I think better developed at the time. Why did they then choose the Olympus for Concorde?
It must have had some merit above the Conway. Having seen the insides of the Conway I think there would have been a fair amount of rework needed to get it to work reliably at continuous supersonic speeds.

The Conway comes across as an engine that never quite lived up to expectations. The BS.100 was always intended for supersonic flight so it might have been a good option? An interesting side note, the BS.100 was at one time the most powerful jet engine in the western world!:eek:

I know that the Conway was suggested for the P.1121 so maybe there was an after burning version that made it at least to the paper stage?:confused: Surely a turbofan would have been a better option for TSR-2? If it was entirely critical that a BS engine be used for the TSR-2 then why not a straight through BS.100?:confused:

Maybe it was a case of “2nd best tomorrow”, the Olympus was I think better developed at the time. Why did they then choose the Olympus for Concorde?
It must have had some merit above the Conway. Having seen the insides of the Conway I think there would have been a fair amount of rework needed to get it to work reliably at continuous supersonic speeds.

I don’t have the reference source at my fingertips, but I’m 99 per cent sure RR did bench-test a reheated Conway at some time. Never flew it though.

As far as I know it wasn’t done at Derby.

I don’t have the reference source at my fingertips, but I’m 99 per cent sure RR did bench-test a reheated Conway at some time. Never flew it though.

I don’t think that RR had a reheated Conway, I’ve never read anything about one. I do know that RR did design a con-di silencer nozzle complete with reverse thrust for the Olympus. This was at a time when BS was still independant. Further, the uprated Conway (201 series Victor) was not the most reliable engine around. it did suffer from a number of compressor failures (zero stage) in service. That would have made the marrying of a reheat unit more difficult and expensive to do.

I know that the Conway was suggested for the P.1121 so maybe there was an after burning version that made it at least to the paper stage?:confused: Surely a turbofan would have been a better option for TSR-2? If it was entirely critical that a BS engine be used for the TSR-2 then why not a straight through BS.100?:confused:

IIRC, BAC wanted a Rolls-Royce engine for TSR.2 but were told they had to use the Olympus.

I don’t think that RR had a reheated Conway, I’ve never read anything about one. I do know that RR did design a con-di silencer nozzle complete with reverse thrust for the Olympus. This was at a time when BS was still independant. Further, the uprated Conway (201 series Victor) was not the most reliable engine around. it did suffer from a number of compressor failures (zero stage) in service. That would have made the marrying of a reheat unit more difficult and expensive to do.

There were a number of proposals for engines following that route – some of the HS1202 fighter proposals in the 70s offered the RB431, which was in essence a straight through Pegasus with reheat

IIRC, BAC wanted a Rolls-Royce engine for TSR.2 but were told they had to use the Olympus.

With SNECMA, their mate on B.Ol.593, Patchway was doing M.45. In due course, infused by Derby fighter propulsors, that led to RB199.

Collaboration pre-occupied people in those days. For (to be) FIAT/Dornier G.91 US had funded Orpheus. In 1957 Bristol part-funded its growth (US MWDP put up 75%), to add a fan, and swivels (funded by Rockefeller), as BS.53. In 1962, grown, + plenum chamber burning, that became BS.100 as an NGTE research orphan: no Brit, leastways RN, wanted single-engined supersonic V/STOL. RR pitched reheated Twin Spey (deflected, not vectored, to by-pass Wibault’s patent) to (a NATO Requirement, and to Joint RN/RAF Reqt. to be) P.1154. W.Germany part-funded RR liftjets and RB153/193 deflected propulsors for (P.1154 equivalents). They also helped to fund grunt into Pegasus, with MAN work-share, for Evaluation Sqdn. Kestrel, and for Do.31 transport. In order to pool UK’s scarce flair on big, hot posteriors MoA imposed work-sharing RR/BSEL on RB153/193/BS.100.

In 1963 RN won its heart’s desire – F-4K. MoA felt reheat-Spey, for a very tight McDonnell production schedule, was all RR could handle, so rejected Twin Spey for P.1154/(RAF/NATO). BS.100 could also ease BSEL’s pain if, as presumed, B.Ol.22R expired. RR was parlous, with just a dribble of Lightning Avons and 2 small carrier-loads of wet and dry Speys. Neither German verticality nor Freddie Laker buying 10 Spey/1-11 would keep wolves at bay. BSEL talked with Pratt on JT9D, and with SNECMA for (draft ASR, to be) AFVG on adapting (VFW.614) M.45H. Was this the new Spey, to fund takeover of Derby?

7 April,1965: BSEL is unbusy. B.Ol.593 survives but talk of 300 Concorde sales is known to be puff. Because BAC leads Dassault on AFVG, SNECMA leads BSEL on M.45G. 1966: BSEL ramps up JT9D talks, which RR must kill to grasp MinTech Launch Aid for (RB207/)RB211. Flushed with Saudi Avons, Allison TF41, Speys everywhere, inc, reheated in F-111K, RR buys BSEL and makes Patchway its military centre to clear Derby for very big fans. When M.Dassault kills AFVG in mid-1967, RR puts (to be RB199) there. In 1970 RR+(MAN)MTU see off a Pratt bid by well-pricing it; BAC/MBB+vendors do the same: Tornado secures Patchway’s future for 30 years.

Could it just be a question of lack of a suitable application in the first half of the 60s to make the exercise worthwhile? Conway-engined 707s and DC-8s hardly sold like hot cakes, and BSE had enough on their plate with the vectored thrust Pegasus and the various Olympuses anyway.
I presume RR must also have pondered the idea, but its ten-tonne fan studies eventually went into the V2500 a few years later.
Anyone else know better?

That could be it. But I have always been intrigued as to why the Olympus got such a lot of applications. Surely something like the Conway or a straight through BS.100 would be better for the TSR-2 than the Olympus?:confused:

Could it just be a question of lack of a suitable application in the first half of the 60s to make the exercise worthwhile? Conway-engined 707s and DC-8s hardly sold like hot cakes, and BSE had enough on their plate with the vectored thrust Pegasus and the various Olympuses anyway.
I presume RR must also have pondered the idea, but its ten-tonne fan studies eventually went into the V2500 a few years later.
Anyone else know better?

Because it became Rolls Royce and RR already had a wide selection of turbofans?

BS was not taken over by RR until 1966, the BS.100 was cancelled in 1965. I have yet to find any reference to any efforts to expand the BR Turbofan family (not even proposals) from the period prior to the merger. Surely there must have been some consideration to the possibility of straight through BS.100’s and Pegasus’s??:confused:

Because it became Rolls Royce and RR already had a wide selection of turbofans?