Was the Vulture as bad history tells us?

[wuzak]

The following ratings are on either 87 octane (DTD 230) or 100 octane (RDE/F/100) fuel. These also appear to be the reduced limits as the design engine speed was 3,200rpm).

Take-Off: 1,800hp @ 3,200rpm, +6psi boost. 3 Minute/1,000ft limit.

Maximum Power: Limit 5 minutes
MS: 1,845hp @ 3,000rpm, +6psi boost, 5,000ft.
FS: 1,710hp @ 3,000rpm, +6psi boost, 15,000ft.

Maximum Power: Limit 30 minutes
MS: 1,700bhp, 2,850rpm, +6lb boost
FS: 1,455bhp, 2,850rpm, +6lb boost

Maximum (rich mixture) Cruise:
MS: 1,480bhp, 2,600rpm, +5lb boost
FS: 1,290bhp, 2,600rpm, +5lb boost

Maximum (rich mixture) Cruise:
MS: 2,600rpm, +2lb boost
FS: 2,600rpm, +2lb boost

Data comes from Air Publication 1801A: The Vulture II and IV Aero-Engines (December 1940) and correspondance with RRHT (the document I have has maximum power and take-off power, but only the limitations for the rest).

Dry Weight is 2,450lb including: "ignition system with bonding and screening, carburettors and induction systems, engine driven fuel pump, coolant pumps and oil pumps, coolant outlet pipes, hand-turning gear, two-speed supercharger with controls and necessary pipe work, also drive for auxiliary gear box, but excluding aircscrew hub, exhaust manifolds or stub pipes, air intakes, connections from coolant inlets and outlets, connections from oil and fuel pumps, oil and coolant."

 

[wuzak]

Some more details:

Bore: 5.0in (127mm)
Stroke: 5.5in (139.7mm)
Capacity: 2,592ci (42.5l)

Length overall: 87.625in (2225.675mm)
Width overall: 35.8in (909.32mm)
Height overall: 42.175in. (1071.245mm)

Bore Spacing: 6.1in (154.94mm)

[For Reference:
Kestrel/Peregrine: 5.625in (142.875mm)
Merlin: 6.075in (154.305mm)
Griffon: 6.9in (175.26mm)]

Supercharger ratios:
MS: 5.5:1
FS: 7.3:1

Reduction Gear Ratio: 0.35:1

The Cylinder banks were number A and B top, C and D bottom, the cylinders in each bank numbered from 1 (at the airscrew end) to 6.

The firing order was
1A, 3D, 2C, 6B, 3A, 5D
1C, 4B, 5A, 6D, 3C, 2B
6A, 4D, 5C, 1B, 4A, 2D
6C, 3B, 2A, 1D, 4C, 5B

Fuel consumption:
At Maximum Take-off: 162UKG/hr

At Maximum Climbing Conditions:
MS: 142.5UKG/hr
FS: 134.5UKG/hr

At maximum cruising power (rich mixture):
MS: 0.61pt/hp/hr (0.07625UKG/hp/hr ~0.549lb/hp/hr)
FS: 0.66pt/hp/hr (0.0825UKG/hp/hr ~0.594lb/hp/hr)

At economical cruising (weak mixture):
MS: 0.53pt/hp/hr (0.06625UKG/hp/hr ~0.477lb/hp/hr)
FS: 0.58pt/hp/hr (0.0725UKG/hp/hr ~0.522lb/hp/hr)

(lb/hp/hr figures based on 7.2lb/UKG.)

Oil Consumption at cruising conditions: 10-20 pints per hour (1.25-2.5 UKG/h)

Oil Temperatures:
Minimum for "opening up": 15°C
Maximum for continuous cruising: 90°C
Maximum for climbing: 90°C
Emergency Maximum (5 minute limit): 95°C
Valve Timing:
Inlet Opens 24° before TDC
Inlet Closes 60° after BDC
Exhaust Opens 64° before BDC
Exhaust Closes 20° before TDC

Coolant Temperature Limits:
Minimum for take-off: 60°C
Maximum for Cruising: 100°C
Maximum for 30 minutes emergency, climbing and level flight: 120°C

 

[Aozora]

Excellent information - deserves two rashers of bacon! The dry weight of the Vulture has long been a mystery.

I have Robert Kirby's book on the Manchester, which goes into some detail regarding the development and problems with the Vulture - one of the main problems centered around the badly designed "starfish" connecting rod design. Will dig it out and do some scans.

BTW: Is the Vulture manual generally available?

 

[tomo pauk]

The take-off power is suspiciously low - 1800 HP @ 3200 rpm? Lumsden gives the same values, though.
Otherwise, the power at low altitudes is comparable with single stage R-2800, while above 14000 ft it does give more power. The exhaust thrust is also greater, for mid-war installations. The weight penalty is somewhat greater than for the R-2800, with cooling system of the Vulture adding another ~500 lbs? The single stage R-2800 was at 2300-2400 lbs, dry.
The max continuous power for the 1-stage R-2800 'B' was 1600 and 1450 HP, in 1st and second gear respectively; A series was at 1500 and 1450 HP. The B series will also give 200 HP more for take off vs. Vulture.
The contemporary Sabre, on +7 lbs boost, was giving a bit more power down low, but it was certainly not a more reliable powerplant than Vulture.
Germans have endured the rough time with BMW 801 on their fighters, but it seems the 801A (on the Do-217) have had less problems, because it was not cleared for Notleistung (being a 'bomber' engine)? The max T.O. ('Start') power of 1560 PS is not that great, either. The Jumo 222 was plagued with problems, the DB 603 is both late and have had own reliability problems initially.
The Soviets have had the AM-38, 1600 CV for take off, but only 1 supercharger speed, set for low level (~4800 ft rated altitude). A bit less weight and problems, but also less power, especially above 10000 ft.

The data card of Mancherster, with powers you state is dated at 7th August 1941. Do we know when the power restriction took place, and on what power ratings?

 

[fastmongrel]

Always intruiged me that the marks I to IV had so much trouble but the mark V in the Hawker Tornado didnt seem to have any trouble or none that I have come across. Is it possible the V was a hand built prototype and that the engine was fine when hand built but it was when put into production that problems appeared.

 

[wuzak]

Always intruiged me that the marks I to IV had so much trouble but the mark V in the Hawker Tornado didnt seem to have any trouble or none that I have come across. Is it possible the V was a hand built prototype and that the engine was fine when hand built but it was when put into production that problems appeared.

I think that the difference was that it was about the right power for the airframe it was powering, while the Manchester was a seriously large aircraft.

The IV and V were the fighter engines, and both were fitted to the Tornado as far as I am aware. The V seems to have been cleared for +9psi boost as well, giving extra power.

 

[wuzak]

BTW: Is the Vulture manual generally available?

It is available from the National Archives of the UK.

Bad Request

The NA code is AIR 10/2699

The Vulture II and IV Aero-Engines | The National Archives

You can get them to copy the document (either paper or digital copy), but that is expensive. Or you could use a professional researcher, which is cheaper.

 

[Shortround6]

The take-off power of 1800hp doesn't seem out of line for 87 octane fuel. Throttle is part shut to limit boost to 6lbs at take-off. Something was going on if there was no increase in power with 100 octane fuel? Just the ability to run on it?
Even the Mercury and Pegasus picked up a bit of power with 100 octane.

A 1944 edition of Wilkinson's "Aircraft Engines of the World" gives take-off power of 2010hp at 3000rpm at 48.2in (9lbs) on 100 octane for the Vulture II but is not a primary source and is several years too late. Dry weight is the same though.
A 1942 edition of "Jane's" gives few details as the engine was still 'restricted' at the time.

 

[wuzak]

The take-off power is suspiciously low - 1800 HP @ 3200 rpm? Lumsden gives the same values, though.

I suspect that because of the mechanical issues extra boost couldn't be used. It is slightly less than maximum power, with the additional 200rpm slightly compensating for the throttling of the carburettor.

The take-off power is suspiciously low - 1800 HP @ 3200 rpm? Lumsden gives the same values, though.
Otherwise, the power at low altitudes is comparable with single stage R-2800, while above 14000 ft it does give more power. The exhaust thrust is also greater, for mid-war installations. The weight penalty is somewhat greater than for the R-2800, with cooling system of the Vulture adding another ~500 lbs? The single stage R-2800 was at 2300-2400 lbs, dry.

Bear in mind that these ratings were for both 87 octane and 100 octane fuel - suggesting that no real benefit (power wise) was gained using the latter. I don't think the R-2800 was ever rated with 87 octane fuel.

The weight of the Vulture would have been reduced in later versions by replacing the reduction gear with a planetary reduction gear system. A svaing of aroun 100-200lbs was expected.

Interestingly there was a tolerance of ±2.5% on the dry weight. Seems rather a lot.

The max continuous power for the 1-stage R-2800 'B' was 1600 and 1450 HP, in 1st and second gear respectively; A series was at 1500 and 1450 HP. The B series will also give 200 HP more for take off vs. Vulture.

The B series was later in timing than the Vulture. I suspect if Rolls-Royce put the time, money and effort into the Vulture that Pratt Whitney did to update the R-2800 A series into the B series it would be susbtantially more power than the figures here. I have had it confirmed by RRHT that Rolls-Royce had tested the Vulture at 2,500hp before its cancellation. Not sure what conditions that was done under, though. Lumsden states that it was tested at 3,000hp, but RRHT could not confirm that.

The contemporary Sabre, on +7 lbs boost, was giving a bit more power down low, but it was certainly not a more reliable powerplant than Vulture.

The contemporary Sabre was, dare I say it, a hand built and fitted prototype engine. This report is dated December 1940.

Germans have endured the rough time with BMW 801 on their fighters, but it seems the 801A (on the Do-217) have had less problems, because it was not cleared for Notleistung (being a 'bomber' engine)? The max T.O. ('Start') power of 1560 PS is not that great, either. The Jumo 222 was plagued with problems, the DB 603 is both late and have had own reliability problems initially.

I think the biggest success for teh DB 603 and BMW 801 came after the Vulture was cancelled and out of production.

Interesting that you mention the Do 217. It had similarly powerful engines as the Manchester, but was quite a bit smaller and lighter.

The Soviets have had the AM-38, 1600 CV for take off, but only 1 supercharger speed, set for low level (~4800 ft rated altitude). A bit less weight and problems, but also less power, especially above 10000 ft.

Big capacity with low rpms.

The data card of Mancherster, with powers you state is dated at 7th August 1941. Do we know when the power restriction took place, and on what power ratings?

Not sure. The document I was quoting is from December 1940.

 

[wuzak]

The take-off power of 1800hp doesn't seem out of line for 87 octane fuel. Throttle is part shut to limit boost to 6lbs at take-off. Something was going on if there was no increase in power with 100 octane fuel? Just the ability to run on it?
Even the Mercury and Pegasus picked up a bit of power with 100 octane.

A 1944 edition of Wilkinson's "Aircraft Engines of the World" gives take-off power of 2010hp at 3000rpm at 48.2in (9lbs) on 100 octane for the Vulture II but is not a primary source and is several years too late. Dry weight is the same though.
A 1942 edition of "Jane's" gives few details as the engine was still 'restricted' at the time.

My correspondant at RRHT gave the Vulture V's take-off power as 1,955hp @ 3,200rpm, +9psi boost.

 

[wuzak]

Something was going on if there was no increase in power with 100 octane fuel? Just the ability to run on it?
Even the Mercury and Pegasus picked up a bit of power with 100 octane.

Was there additional boost involved?

 

[Shortround6]

Yes, The Mercury was sometimes run at up to 9lb of boost in Blenheims with 100 octane fuel, the outer tanks were filled with 100 octane for take-off and combat with the inner tanks filled with 87 octane for cruise.

The Pegasus went from about a 5.5lb limit to 6.75lb limit which is not a big increase but worth about 60-80hp depending on altitude and supercharger gear, on basically a 1000hp engine.

Neither engine had much in the way of physical changes. The Hercules had a constantly changing amount of finning/cylinder head changes to increase cooling (among other things) which allowed it to make much more power as fuel improved.

 

[tomo pauk]

I suspect that because of the mechanical issues extra boost couldn't be used. It is slightly less than maximum power, with the additional 200rpm slightly compensating for the throttling of the carburettor.

Guess you're right.

Bear in mind that these ratings were for both 87 octane and 100 octane fuel - suggesting that no real benefit (power wise) was gained using the latter. I don't think the R-2800 was ever rated with 87 octane fuel.

100 oct and better for the R-2800; the 87 oct was used in preliminary calculations, design test of the early prototypes and single-cylinders?
Use of 100+ oct should enable it to run on greater boost, and hence the power, should engine withstand it, of course.

The weight of the Vulture would have been reduced in later versions by replacing the reduction gear with a planetary reduction gear system. A svaing of aroun 100-200lbs was expected.

Hmm - why was the original reduction gear so heavy in the 1st place?

Interestingly there was a tolerance of ±2.5% on the dry weight. Seems rather a lot.

Quite a bit, most of the tolerances for single items being far less than 1%?

The B series was later in timing than the Vulture. I suspect if Rolls-Royce put the time, money and effort into the Vulture that Pratt Whitney did to update the R-2800 A series into the B series it would be susbtantially more power than the figures here. I have had it confirmed by RRHT that Rolls-Royce had tested the Vulture at 2,500hp before its cancellation. Not sure what conditions that was done under, though. Lumsden states that it was tested at 3,000hp, but RRHT could not confirm that.

The B series was started being available Jan 1942 (both single and 2-stage), for more than penny packets. The A series from Jan 1941.
The Vulture have had the prerequisites for a really powerful engine - big displacement, running on high RPM. The 2500-3000 HP potential was realistic, if we only look at 'paper values'. It is still a question of whether the engine was conceived 'right' from the get-go to withstand such great strains while in service use.
It might be an interesting scenario where the Griffon gets cancelled all together, and that resources are used to iron out the Vulture. Single stage versions for Tornado, Firefly and Barracuda, 2-stage versions for Tempest, Sea Fury and Firefly again?

The contemporary Sabre was, dare I say it, a hand built and fitted prototype engine. This report is dated December 1940.

Thanks for the date. BTW, how big a truth is that it took some time to persuade Bristol to help out with sleeves (or production of sleeves?) for the Sabre?

I think the biggest success for teh DB 603 and BMW 801 came after the Vulture was cancelled and out of production.

Indeed.

Interesting that you mention the Do 217. It had similarly powerful engines as the Manchester, but was quite a bit smaller and lighter.

It took some time for the Do-217 to receive the similar power as the Manchester, circa early/mid 1943.

Big capacity with low rpms.

Indeed - a low-risk approach for decently high power.

 

[tomo pauk]

Kindly provided by Neil Stirling, charts for late 1930/early 1940's engines. Give the TO power for the Vulture II at ~1830 HP at 3200 rpm, also clear a bit about the Mercury running on greater boost for TO and at lower altitudes.
link

 

[rinkol]

Nobody has mentioned that DB worked on an engine of similar configuration, the DB 604. This was abandoned in 1942 although, at least on paper, the specifications looked pretty good. Does anyone have any information to add?

Robert

 

[tomo pauk]

Not sure what do you have particularly in mind, but here it goes: bore x stroke 135x135mm, 46.5L, CR = 7.5, to use 87 oct fuel, two-stage supercharger (??, but v. Gersdorff et al say so*), 1080 kg dry, TO power 2500 PS at 3200 RPM, FTH at 5.1 km. See also here; two stage S/C not mentioned, and the FTH looks too low for such anyway.

*by same source, five experimental DB 604 engines were tested on benches and aboard the Ju-52 from 1939, program cancelled in 1942 by RLM

 

[stona]

All 508 production Vultures were designated for use in the Manchester. Given that as early as late 1940 the Air Staff (if not Bomber Command) was viewing the Manchester as nothing more than a stop gap, pending the introduction of the Lancaster and the hopeful re-engineing of the Halifax, it really had no chance.

Credit is due to the engineers who persevered with it and particularly the men of No. 207 Squadron and later No. 97 Squadron who flew the thing early on, but it was all for naught.

The surprising thing is that Rolls Royce didn't officially terminate the Vulture programme until April 1942. If it had been a German project the RLM would still have been financing it at the end of the war

Cheers

Steve

 

[nuuumannn]

Credit is due to the engineers who persevered with it and particularly the men of No. 207 Squadron and later No. 97 Squadron who flew the thing early on, but it was all for naught. The surprising thing is that Rolls Royce didn't officially terminate the Vulture programme until April 1942.

From a glass half empty point of view, you could argue that had the Vulture been a success, then perhaps the Manchester Mk.III might have been later into service and probably not called Lancaster?

I read an interesting excerpt from The Magic of a Name that it was Hives who suggested to Chadwick that replacing the Vulture with the Merlin would have been a better option before the Manchester was put into production.

 

[tomo pauk]

Even if the Vulture was providing reliable 2000 HP, the layout with 4 Merlins has several benefits. Major one being the far less problematic engine-out situation. The take off power would be 5120-5600 HP, even on not too much over-boosted Merlins, vs. 4000 for two Vultures.

 

[stona]

I read an interesting excerpt from The Magic of a Name that it was Hives who suggested to Chadwick that replacing the Vulture with the Merlin would have been a better option before the Manchester was put into production.

I have it from more than one source that Rolls Royce informed Chadwick that the Merlin XX was to be produced as a self contained power plant, suitable for a multi engine aircraft. It might well have been Hives who wrote or spoke to Chadwick. Much of this sort of thing was done personally, casually and unofficially. Chadwick had never given up on the four engine concept, indeed he seems to have been aware all along that it was going to offer the best option for the sort of bombers required by the stream of Air Ministry specifications issued in the late 1930s. Rolls Royce/Hives can't be given credit for that, Chadwick, Dobson and Rowe himself deserve that.

From the moment J.E.Serby, Principal Technical Officer in the Department of the Air Member for Production and Development, made a hand written comment on a copy of the Avro minutes which laid out just how easy it would be to make the Manchester-Lancaster changeover, with the words "Please initiate contract action for 1 prototype" on or about 10th September 1940, both the Manchester and the Vulture were on borrowed time.

Cheers

Steve