Vulture Engine

[Jenelle Centeno]

TheRolls-Royce Vulture was a British aero engine developed shortly before World War II that was designed and built by Rolls-Royce Limited. The Vulture used the unusual "X-24" configuration, whereby four cylinder blocks derived from the Rolls-Royce Peregrine were joined by a common crankshaft supported by a single crankcase. The engine was originally designed to produce around 1,750 horsepower (1,300 kW) but problems with the Vulture design meant that the engines were derated to around 1,450 to 1,550 hp in service by limiting the maximum rpm.

Although several new aircraft designs had been planned to use the Vulture, work on the engine's design ended in 1941 as Rolls-Royce concentrated on their more successful Merlin design. Another 24-cylinder engine, the Napier Sabre, proved more successful after a lengthy development period.

The supercharged Rolls-Royce Kestrel and its derivative, the Rolls-Royce Peregrine, were fairly standard designs, with two cylinder banks arranged in a V form and with a displacement of 21 litres (1,300 cu in). The Vulture was, in effect, two Peregrines joined by a new crankcase turning a new crankshaft, producing an X engine configuration with a displacement of 42 litres (2,600 cu in). The Vulture used cylinders of the same bore and stroke as the Peregrine, but the cylinder spacing was increased to accommodate a longer crankshaft, necessary for extra main bearings and wider crankpins.[1][2]

The engine suffered from an abbreviated development period because Rolls-Royce suspended Vulture development in 1940 during the Battle of Britain to concentrate on the Merlin, which powered the RAF's two main fighters, the Hawker Hurricane and Supermarine Spitfire, and as a consequence the reliability of the Vulture when it entered service was very poor. Apart from delivering significantly less than the designed power, the Vulture suffered from frequent failures of the connecting rod big end bearings, which was found to be caused by a breakdown in lubrication, and also from heat dissipation problems. Rolls-Royce were initially confident that they could solve the problems, but the company's much smaller Merlin was already nearing the same power level as the Vulture's original specification,[i] in part because of its accelerated development in 1940, and so production of the Vulture was discontinued after only 538 had been built.[3]

The Vulture had been intended to power the Hawker Tornado interceptor but with the cancellation of Vulture development, Hawker abandoned the Tornado and concentrated on the Hawker Typhoon, which was powered by the Napier Sabre. The cancellation caused the abandonment of the Vulture-engined version of the Vickers Warwick bomber. The only aircraft type designed for the Vulture to go into production was the twin-engined Avro Manchester. When the engine reliability problems became clear, the Avro team persuaded the Air Ministry that switching to a four-Merlin version of the Manchester, which had been in development as a contingency, was preferable to retooling Avro factories to make the Handley Page Halifax. The resulting aircraft was initially called the Manchester Mark III and then subsequently renamed Avro Lancaster, going on to great success as the RAF's leading heavy bomber.

I do not recall any mention of dual crankshafts in regard to the Vulture. RR did some work on the H-24 Merlin, and they did build the sleeve-valve Eagle H-24. Both of those engines had dual crankshafts.

Great write up Mr. Pearce. Another case of haste makes waste. Might remind me of the F-35 but the Air Ministry seemed to have better cause for urgency. Considering the Griffon had 36 liters, the Vultures 42.5 liters seems to not justify the extra 12 cylinders and related frontal area. At least it had more capacity than the Sabre. Thank you.

Sean, my understanding is that the F-35 went into production before all the bugs were worked out, and then the manufacturers have had to rebuild and update the already produced planes with the improvements. As for the bore stroke ratio, the advantages of a short stroke in racing engines was already well established. In aircraft engines there was a long established preference for under square engines. This was an international trend. While piston speed was one issue that limited RPM, crank lubrication and other issues were also compelling. I am a great fan of the Sabre, but it may not have been the most cost effective war plane engine. In war, cost is king.

Thanks Pete, I had forgotten about the Scottish one, but I believe you are correct in saying that it is from the B20 prototype. So it sounds as though there are a maximum of three that are 'intact'. Some years ago I saw some evidence (at RR Derby, I think) that a least one Vulture was used to test a contra-prop and I was wondering if any else had heard of this or any other Vulture developments.

Well, the clutch-packs, they look exactly the same shape, and about the same size, as the clutch-packs from a Bristol Hercules engine (ironically, an example of which is next in line in that photograph)! Is it possible that a Rolls-Royce engine was using, or copying, a Bristol supercharger clutch-pack?

I seem to remember seeing an article (with a photo) in the Lincolnshire Echo which described the recovery of two Vulture engines and guess it would have been during the late Seventies or possibly early Eighties. Annoyingly, I don't remember the location of the dig though, or anything else about it.

Over the years I have seen some examples of the RR Vulture 24 cilinder X-engine. One was reasonable having been recovered from soft ground in the northern part of Holland. Ours came from the north sea and looks terrible and another one we only recovered gears and other internals from.

So no engines have survived not even at the Science Museum? The last Manchester was recovered from a quarry by an American team and scrapped. Pics in the book by Mr Kirby. Pity. I know where the wreck of one lies in the IJsselmeer but it is very shallow and not worth to recover for a restoration.

Cees. it is several years since I spoke to Stan Grainger (the chap in question) ,I was given to understand that, that was the only one they had , but that is not to say the only one in existance ,( or that since my conversation with him that they have not aquired another).

there are at least 2 vultures in store with the RAF musuem with a third one on loan to RR. The one on loan and the one that I saw (pretty reasonable condition) were recovered by the RAF in the 70's from a Manchester crash. The other I believe was a sea recovery.

Two Manchester engines are in museums in the north and south of Holland. As I said ours came from the north sea and only just resembles a Vulture with the cilinder barrels and engine mounting being recognisable. The one in the north is very complete and still has its prop mounted. It came from a Manchester which crashed in soft soil.

Of course it would be sacriledge if a museum would only even contemplate such a conversion :eek: . But there are sections still around (Kermit Weeks, Sandtoft etc.) that can be used for such a project. Don't forget the Manchester wasn only the forerunner of the Lanc. It was a type in itself of which high hopes were placed. But it represented a moment in time of Bomber Command that deserves a place. Why having only succesful types on display? It would be boring as that way most museums have similar collections which is to a certain extent already the case (in my very humble opinion).

Given we are discussing engines of Manchesters what other bits of the type still survive? Anything of note or just a few piles of twisted metal? I cant say I have ever seen reference to anything but worth a try!

Mostly twisted wreckage. But I believe the RAF Museum S-for Sugar was originally ordered as a Manchester. So technically she could still be a Manchester that was converted on the production line into a Manchester III AKA Lancaster I.

I have this book in my library and very good it is. The problem with the Vulture was in its big end design, when RR changed it to a design that was derived from radial engine technology the issue went away, but it was too late as the Merlin engined MkIII was already in production and removing the Vulture from the production schedules at RR factories simplified things a lot.

Rolls Royce Vulture The Rolls Royce Vulture.1 If a little is good, then more is better, but such was not the case when Rolls-Royce mated a pair of V12 Kestrel engines with a common crankcase creating a "X-24" cylinder engine. The Vulture was developed shortly before World War II, but the results were very disappointing.

The engine was originally designed to produce around 1,750 horsepower (1,300 kW), but continuing problems with the Vulture design meant that the engines were derated to around 1,450-1,550 hp in service by limiting the maximum running speed.As well as delivering less power than was expecteded, the Vulture suffered from frequent failures of the big end connecting-rod bearings, which was found to be caused by a breakdown in lubrication, and also from other engine heat dissipation problems.

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