WI The Rolls Royce Vulture is a success

wuzak · Aug 13, 2011

Comparative specs of Volkert's high speed bomber and the winning P.13/36 aircraft.

Code:

                 HP HSB             Manchester I          HP HP.56
Span           88'6"/27.0m          90'1"/27.5m         85'0"/25.9m
Length         71'6"/21.8m         68'10"/21.0m         66'6"/20.3m
Wing Area     988ft²/91.9m²       1131ft²/105.2m²      975ft²/90.7m²
Max weight  36,500lb/11,162kg    50,000lb/22,680kg   39,000lb/17,690kmh
Engines        2 x Vulture          2 x vulture         2 x Vulture
Max Speed     380mph/611km/h       265mph/426kmh       320mph/515kmh

The HP.56 would be redesigned as the 4 engined HP.57 Halifax.

Shortround6 · Aug 13, 2011

wuzak said:
This is true. The original concept for twin engined bombers like the Manchester (it was not considered a heavy bomber, but a medium bomber - the Short Stirling and Supermarine 317 were considered heavies) was that the use of two powerful engines would be more efficient due to less drag than four smaller engines. Which is true, but it didn't work out that way - partly because of the problems with the Vulture, and it not being powerful enough for single engine duty.

Compare with the Mosquito. A much smaller and lighter twin, which didn't give much away in power. Single engine performance was more than acceptable.

The Whitley was often referred to as a heavy bomber and the Vickers Warwick first flew with Vultures.

Definitions or classifications changed with time but a 40-50,000lb bomber in 1939/40 was a heavy bomber.

Milosh · Aug 14, 2011

pbfoot said:
What WW2 aircraft was as bad as the Manchester , the reason the Lanc tail shimmied is that iy lacked a locking tail wheel which was common on Brit A/C it saved money , as did other basic items like deicing equipmemt . IIRC there was an issue on prop feathering possibly a lack of a resovoir

He 177, B-29, SB2C, Barracuda for starters

fastmongrel · Aug 14, 2011

pbfoot said:
What WW2 aircraft was as bad as the Manchester

Dozens and dozens of aircraft with a good few that made the Manc seem like a wonder plane.

pbfoot · Aug 14, 2011

fastmongrel said:
Dozens and dozens of aircraft with a good few that made the Manc seem like a wonder plane.

Ok you convinced me it was a wonder aircraft compared to many. And Bader was a wonderful tastician and Harris and Broadhurst liked Colonials . But in all seriousness the aircraft had major flaws can you imagine the prop feathering and unfeathering while carrying a full load it would certainly be disconcerting . The thing had a rubbish Hydraulic system poor engines the list goes on

wuzak · Aug 17, 2011

fastmongrel said:
From the bits and pieces I have read about the Vulture (not a great deal out there) it seems that the RR engineers had worked out the problems, had a solution and werent too far off getting the engine working at full power. According to Bill Gunston World Aero Engines 2nd edition p143 in march 41 the Vulture was rated for takeoff at 2,100 hp using 100 octane and 9lbs of boost (no rpm given).

RRHT gave me the following numbers:

Vulture II - takeoff power 1800hp @ 3200rpm, +6psi boost - max 3 minutes
Vulture IV/V - takeoff power 1955hp @ 3200rpm, +9psi boost - max 3 minutes

They also gave me some operating limits for all marks:
Max climb - 30 minutes at 2850rpm, +6psi boost (also max one engine out for Manchester)
Cruise in auto weak - continuous at 2600rpm, +2psi boost.

fastmongrel · Aug 17, 2011

wuzak said:
RRHT gave me the following numbers:

Vulture II - takeoff power 1800hp @ 3200rpm, +6psi boost - max 3 minutes
Vulture IV/V - takeoff power 1955hp @ 3200rpm, +9psi boost - max 3 minutes

They also gave me some operating limits for all marks:
Max climb - 30 minutes at 2850rpm, +6psi boost (also max one engine out for Manchester)
Cruise in auto weak - continuous at 2600rpm, +2psi boost.

RRHT are the chaps who would know, perhaps the 2,100hp figure given by Gunston was a development engine. Still its obvious that there was a lot of potential in the design and it wasnt as some believe fundamentally flawed.

wuzak · Aug 17, 2011

fastmongrel said:
RRHT are the chaps who would know, perhaps the 2,100hp figure given by Gunston was a development engine. Still its obvious that there was a lot of potential in the design and it wasnt as some believe fundamentally flawed.

The Mks IV and V were described as "fighter" engines, btw. The V was fitted to the Tornado prototype.

wuzak · Aug 23, 2011

From what I can figure, using rudimentary calcs, the 30 minute limit for the Vulture was around 1500-1600hp, and the continuous cruise 1100-1200hp.

wuzak · Sep 12, 2011

Looking at the development of the Merlin makes for an interesting comparison.

The Merlin II with 87 octane fuel had a maximum power of 1030hp @ 3000rpm and 5500ft altitude.

The Merlin III with 100 octane fuel managed 1310hp @ 3000rpm and 9000ft altitude.

Skip forwarrd to the post war 620 series engines - with two speed two stage compressors.

The Merlin 620 was rated at 1175hp continuous cruising power (I would presume the maximum continuous) at 2650rpm at "medium" altitudes. The maximum emergency power was 1795hp @ 3000rpm, +20psi boost.

Figures from Rolls-Royce Merlin - Wikipedia, the free encyclopedia

So, in 6 or 7 years the Merlin went from a maximum boost of +6psi (+9psi with 100 octane fuel) and 1030hp maximum for short periods to +9psi and 1175hp continuous power.

With a few years' development the 30 minute limit of 2850rpm and +6psi for the Vulture may have become the maximum continuous.

wuzak · Sep 20, 2011

Some more info on the Vulture from the RRHT:

The full throttle heights for the Vulture were 4000ft in Moderate Supercharge (MS) gear and 13,500ft in Full Supercharge (FS) gear.

Vulture II
(MS gear):
Max t/o (SL) - 1800bhp, 3200rpm, 6lb boost, 162gph;
Max climb - 1700bhp, 2850rpm, 6lb boost, 142.5gph;
Max cruise - 1480bhp, 2600rpm, 5lb boost, 0.61 pt/bhp/hr
(FS gear):
Max climb - 1455bhp, 2850rpm, 6lb boost, 134.5gph;
Max cruise - 1290bhp, 2600rpm, 5lb boost, 0.66 pt/bhp/hr

fastmongrel · Sep 20, 2011

Tried drawing a B 29 with Vulture engines using autocad and photoshop but it just wont work probably need tomopauks skills.

I am slowly working on an alternative history of the Boeing Washington in RAF service with the improved turbocharged Vulture engine. So far its Dec 44 No 617 and No 9 squadrons are training with there Stabilised Automatic Bomb Sight equipped Washington Mk1 bombers. Very soon tallboys and Grand Slams are going to be dropping from great heights and doing some very nasty things to German concrete.

wuzak · Sep 20, 2011

I bought a GA drawing of the Vulture from RRHT. Hopefully it arrives soon.

Something like that would give you some better ideas on how to unstall it, I think.

fastmongrel · Sep 20, 2011

I think its more my incompetence with the software thats the problem. Bought a 2nd hand copy of Autocad but no instructions with the disc which doesnt help

wuzak · Sep 20, 2011

Do you have a n autocad file of the B-29 to start with?

wuzak · Sep 20, 2011

What style radiator are you going to use?

A system like the Avro Manchester?

http://www.myhobbylinks.com/images/3V-A19-MANCHESTER.jpg
http://cdn-www.airliners.net/aviation-photos/photos/8/4/9/1681948.jpg

A Chin radiator like the Tornado?
http://www.edcoatescollection.com/ac6/Hawker Tornado.jpg
http://de.valka.cz/files/hawker_tornado.jpg
http://www.airwar.ru/image/idop/fww2/tornado/tornado-7.jpg

Or a more remote installation like the Tornado prototype had originally?
http://s43.radikal.ru/i101/1002/5d/ce87c0108d05.jpg

Perhaps an annualr radiator, similar to what was trailed on the Typhoon
http://www.patricksaviation.com/files/photos/full/16220_11703.jpg
The Hawker Tempest Page

Maybe a German style annualr radiator, like the Fw190D?
http://www.scaleworkshop.com/gallery/images/fw190d9jv44cw_22_old.jpg
http://www.deadlybirds.com.br/pt/alemanha/avioes/fw_view/focke-wulf_fw190-1.jpg

A semi-annular radiator like the Shackleton
http://upload.wikimedia.org/wikipedia/commons/0/03/SAAF-Avro_Shackleton-002.jpg
http://www.airplane-pictures.net/images/uploaded-images/2008-2/24/11030.jpg
http://upload.wikimedia.org/wikipedia/commons/0/00/SAAF-Avro_Shackleton-003.jpg

Could use a radiator location like the inlet for teh intercoolers and turbos on the B-50, which I suppose would be similar to the Manchester.
http://cdn-www.airliners.net/aviation-photos/photos/3/3/9/1162933.jpg
http://www.aviastar.org/pictures/usa/boeing_b-50_1.jpg
http://upload.wikimedia.org/wikipedia/commons/3/38/Boeing_B-50_USAF.jpg

I guess the chin radiator would end up looking like the XB-39
http://www.strange-mecha.com/aircraft/Prototype/xb39.JPG
http://1000aircraftphotos.com/Contributions/Larkins/2972.jpg
http://1000aircraftphotos.com/Contributions/McMahan/3319L.jpg

fastmongrel · Sep 21, 2011

I have been using the cowling and radiator off the Tornado thinking it looks very similar to the Merlin power egg. The theme of my alternative B 29/Washington Mk1 is that the RAF actually ask Boeing to build a big bomber using the ideas of Barnes Wallis in 1940. Boeing had started work on the B29 so offered the RAF a lightly modified B29 with a quick engine change nacelle and RAF radios and other equipment. The RAF orders 500 off the drawing board and with the money Boeing take on more staff in 1940 and start working at full speed to get the Washington flying. The USAAC gets its order in as real life and gets the lions share of production but the B29 rolls off the production line early enough for the RAF to use them for precision daylight bombing in Europe.

Dont know if I have the nerve to make the super Vulture the engine for the US models that might get me sent to Guantanamo Bay

fastmongrel · Sep 21, 2011

Yes I think the work was already done for me but didnt realise. This is almost how I imagined the Washington looking like just a slightly more pronounced chin radiator like a Merlin power egg. Though the Shackleton radiators have got me thinking.

wuzak · Sep 22, 2011

Is it me or are the nacelles of the B-29 and, subsequently, the XB-39 huge?

The lower intake on the B-29 feeds air to the intercoolers, oil coolers and the turbos.

My personal preference would be to have the intake for the radiators closer to the rear - as in the B-50. The scoops would be similar to the P-51 and the B-50, in that there would be a boundary layer separator.

The radiator outlet would probably be to each side of the nacelle, probably involving the turbo and wastegate exhausts too.

As best I can figure from dodgy 3 view drawings is that the nacelle on the Manchester is around 50-52in in diameter. The nacelle on the B-29 is somewhat larger at its maximum, but I think that the bulkhead where the QEC module fits is smaller. The V-3420 is shallower (by about 8 inches), but wider than the Vulture (by 20 inches).

The single stage 2 speed Vulture is 10in longer than the R-3350, but 12in shorter than the V-3420 and 8in shorter than the R-4360. I would consider keepping the 2 speed drive and engaging that if flying above the critical altitude of the turbos. Using a pair of high altitude B-series turbos, as the B-29 did, should give a critical altitude of 30,000ft.

Once the Vulture QEC is designed I would give the turbos over to RR's gas turbine department, which includes Hooker, to see if they could be improved.

Initial testing of the QEC on the newly reliable Vultures in late 1941 give a maximum cruising of 1500hp, max climb of 1700hp and takeoff and war emergency of 2000hp. Testing at t/o rating of 2500hp is complete in mid 1942, this giving a maximum continuous of 1800hp for high speed cruise, and 1400hp for lean cruise. A set of the are then sent to Boeing for installation on the XB-29B (the British/Rolls-Royce version).

Further development of the Vulture has takeoff power up to 2800hp by the time the first production B-29Bs arrive in the UK. After the initial batch the bombers are flown over as B-29As with the Wright engines fitted, which are then replaced by Rolls-Royce with the Vulture QECs and other British equipment fitted. It is late 1944 before enough Washington IIs make it to the UK to form an operational squadron.

wuzak · Sep 22, 2011

Shortround6 said:
When comparing some of these engines, especially for bomber use, you might want to compare the cruise power or 30min/1 hour ratings vs the 5 min or WEP power settings. or take-off power vs WEP settings.

The P&W R-2800 in it's bomber versions single stage two speed supercharger was good for a mere 2000hp for take off but it was good for 1450hp at 13,000ft until the fuel ran out, it wasn't economical or a normal "cruise" setting but the engine would do it.
A Centaurus MK IV was good for 1850hp at 14,250 ft for 30 minutes or so.

While the air-cooled radials didn't have the peak power of the liquid cooled engines the difference between the the take-off power and max continuous and cruise power settings was some what less than the drop in power for the liquid cooled engines.

wuzak said:
Some more info on the Vulture from the RRHT:

The full throttle heights for the Vulture were 4000ft in Moderate Supercharge (MS) gear and 13,500ft in Full Supercharge (FS) gear.

Vulture II
(MS gear):
Max t/o (SL) - 1800bhp, 3200rpm, 6lb boost, 162gph;
Max climb - 1700bhp, 2850rpm, 6lb boost, 142.5gph;
Max cruise - 1480bhp, 2600rpm, 5lb boost, 0.61 pt/bhp/hr
(FS gear):
Max climb - 1455bhp, 2850rpm, 6lb boost, 134.5gph;
Max cruise - 1290bhp, 2600rpm, 5lb boost, 0.66 pt/bhp/hr

So, the Vulture wasn't too far off in its detuned state?

160hp down for max continuous rating at 13,000ft (FTH FS gear 13,500) comapred with an R-2800, and 400hp on 30 minute rating comapred with the Centaurus IV (what year was that, btw?).

WI The Rolls Royce Vulture is a success

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