Shortround6
Major General
The British were also fooling with the Warwick bomber, first flight 13 August 1939 and by the time the engine situation was figured out it had helped them decide that twin heavies were not the way to go.
Was the Vulture as bad history tells us?
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To get back on this:
DB was giving +-3% tolerance on the DB 603, dry weight. So my statement of 'usually less than 1%' is way off.
DB was giving +-3% tolerance on the DB 603, dry weight. So my statement of 'usually less than 1%' is way off.
Yes, the Warwick was something of an orphan and after B.12/36 and P.13/36 the firms that had demonstrated an interest in B.1/35 ceased design work, except Vickers, where Pierson wished to continue with it. At this time, the Wellington had not been tested and since HP and Armstrong Whitworth were dropping B.1/35, the immediate heavy bomber needs of the RAF would have to be met by the Wellington. The Warwick's design was protracted since work was concentrated on the Wellington. It was very much a relic from yesteryear since it couldn't compete with the four engined heavies by 1942, when it entered production; the needs of B.1/35 were obsolete and overtaken by wartime experience.
Definitely, Tomo. You don't even need to examine the figures, just look at the performance and load carrying capability of the Lancaster compared to the Manchester.
A fighter engine doesn't work nearly as hard as a bomber engine. In a fighter, five or six minutes after takeoff you're up to altitude, and throttled back to cruise power. In a bomber, its a longgg grind up to altitude, with the engines working hard all the way up. Fighters in 40/41 carried maybe a couple of hours of fuel, bombers fly a lot longer mission profile. Much of the higher reliability in the Tornado might have been the lighter workload on the engine compared to the Manchester.
That is all I think I know.
- Thread starter
- #25
wuzak
Captain
Some information/claims by Robert Kirby, Avro Manchester:
I have seen the con-rod design as a forthcoming fix, but not for the crankcase which was, in any case, already split.
A couple options here:
Kirby also says that the material chosen for the con-rod bolts was "high Brinell" (ie hard) and low ductile material. The latter means that the material is not very "stretchy" and breaks quite suddenly.
I find that difficult to believe as I would have imagined that the bolt material would have been any different to other Rolls-Royce products.
[The rod design shown above was, IIRC, the second design. The first design had only 2 bolts, the two halves being joined on one side by the wrist pin for one of the rods, the halves pivoting around and being clamped by 2 bolts on the opposite side.]
The big difference, of course, was that there were two bolt lengths, shorter than Rolls-Royce would have typically used.
The author also states that there was some confusion as to the tension that should be applied to the bolts. That some were, in fact, over-tightened, and that the official tension figure was reduced at some point.
There had been miscalculations in the rod bolt design, and as such they were structurally on the limit at the reduced rpm limit of 2850rpm.
Bearing issues had been resolved with revised material specifications (and the dowels in the blocks to prevent movement and main bearing failure).
The balance pipe solution to the overheating/fire issue was resolved but took some time to retrofit to aircraft in the field. This is most likely due to higher priorities afforded the Merlin and Griffon in the BoB and the year after.
I have seen the con-rod design as a forthcoming fix, but not for the crankcase which was, in any case, already split.
A couple options here:
- The new crankcase revised how the halves joined together. IIRC the crankcase was held together using diagonal bolts, and a fix for the movement of the halves was to insert dowels.
- The updated design was to use paired fork and blade rods, necessarily offsetting two of the cylinder blocks.
Kirby also says that the material chosen for the con-rod bolts was "high Brinell" (ie hard) and low ductile material. The latter means that the material is not very "stretchy" and breaks quite suddenly.
I find that difficult to believe as I would have imagined that the bolt material would have been any different to other Rolls-Royce products.
[The rod design shown above was, IIRC, the second design. The first design had only 2 bolts, the two halves being joined on one side by the wrist pin for one of the rods, the halves pivoting around and being clamped by 2 bolts on the opposite side.]
The big difference, of course, was that there were two bolt lengths, shorter than Rolls-Royce would have typically used.
The author also states that there was some confusion as to the tension that should be applied to the bolts. That some were, in fact, over-tightened, and that the official tension figure was reduced at some point.
There had been miscalculations in the rod bolt design, and as such they were structurally on the limit at the reduced rpm limit of 2850rpm.
Bearing issues had been resolved with revised material specifications (and the dowels in the blocks to prevent movement and main bearing failure).
The balance pipe solution to the overheating/fire issue was resolved but took some time to retrofit to aircraft in the field. This is most likely due to higher priorities afforded the Merlin and Griffon in the BoB and the year after.
GregP
Major
Seems to me the Vulture was the ultimate development of the Kestrel ... being composed of two Peregrines mated to each other, and the Peregrine was a development of the Kestrel. The Kestrel seems like it was a reasonably reliable engine, and it is difficult to see how the Vulture could be considered a failure. Since the Kestrel was considered "reliable," it is tough for me to conceive why they could not have expended some effort to find out why the Vulture caught fire and correct the situation. The Peregrine might not have had much military application at 700 - 900 HP, but the Vulture at about twice that DID.
I cannot say there wasn't a market for 1,500 - 1,800 hp engines ... there were plenty of applications, from the B-25 Mitchell to the TBF Avenger to the Handley Page Halifax ... all used engines around 1,800 HP or so and there are PLENTY more on all sides of the war. So, there was no shortage of applications for the engine class.
Still, it seems the Vultures as flown DID have some issues. I see that the development of a simpler engine (the Merlin) might have been seen as more important, but the later Napier Sabre was another 24-cylinder application that DID get debugged and put to good use. They might have had two if they had pursued the Vulture. I fully realize it didn't happen, but the potential for success seems solidly there, yet unpursued.
I cannot say there wasn't a market for 1,500 - 1,800 hp engines ... there were plenty of applications, from the B-25 Mitchell to the TBF Avenger to the Handley Page Halifax ... all used engines around 1,800 HP or so and there are PLENTY more on all sides of the war. So, there was no shortage of applications for the engine class.
Still, it seems the Vultures as flown DID have some issues. I see that the development of a simpler engine (the Merlin) might have been seen as more important, but the later Napier Sabre was another 24-cylinder application that DID get debugged and put to good use. They might have had two if they had pursued the Vulture. I fully realize it didn't happen, but the potential for success seems solidly there, yet unpursued.
- Thread starter
- #28
wuzak
Captain
I got this from the Rolls-Royce Heritage Trust a few years ago:
"No complete engine is known to survive. The RAF Museum has three incomplete engines from crash-sites, none of which is, or ever will be, capable of running. One of these engines is on loan to the Derby & Hucknall Branch of the Rolls-Royce Heritage Trust and is displayed at Hucknall. At least one other exists in Holland."
- Thread starter
- #29
wuzak
Captain
If it flew to the Ruhr and back, carrying as much as 8,000lb of bombs on the outward leg, that must be considered a success!
Blackburn B20 | BAE Systems | International
- Thread starter
- #30
wuzak
Captain
There were several problems, but the main outstanding issue at cancellation was the connecting rods and the bearings.
Rolls-Royce had been working through the issues, but development was suspended during the Battle of Britain so that Rolls-Royce could concentrate on improving Merlin performance. Cancellation came in 1941, so that Rolls-Royce could concentrate on the Merlin and Griffon.
The Peregrine and Exe were also affected by this, and Rolls-Royce wanted to have the Crecy cancelled too, but were told to continue with that.
fastmongrel
1st Sergeant
Seems like the B20 could have been a good plane given time and money to iron out the bugs.
Admiral Beez
Captain
Attachments
Perhaps it was fortunate that it didn't work and wasn't developed. There is no way you can crowbar a Vulture into a P-51 and if you did it would use too much fuel to be a long range escort. Without the switch to mass Merlin production would the Mosquito ever get made?
GregP
Major
To be clear, I was not saying they should have pursued the Vulture to the exclusion of the Merlin, and perhaps there was simply not enough manpower to pursue all the projects.
All I was saying is that there was a solid area of application for an 1,800 hp engine. In the end, I'd rather fly behind a V-12 than a 24-cylinder engine in battle just due to complexity, but the engine as conceived had applications.
All I was saying is that there was a solid area of application for an 1,800 hp engine. In the end, I'd rather fly behind a V-12 than a 24-cylinder engine in battle just due to complexity, but the engine as conceived had applications.
No doubt that if it was sorted to the extent the Merlin and Griffon were then you are talking about bombers with B-29 type performance and fighters as they eventually had with the Tempest and Fury. But they were never even thinking about such planes let alone designing and building them.
GregP
Major
And I don't think the Vulture Henley is all that ugly ...
To me, it looks better than a stock Hurricane ... just thinking about a single-seater with the pic on the screen. I'm thinking of a bubble canopy ... but, that's a "what if" that never happened. But, it's the first time I ever thought of a Vulture-powered Hurricane. Might have to relocate that little scoop in front of the windscreen if you're going to play fighter pilot.
To me, it looks better than a stock Hurricane ... just thinking about a single-seater with the pic on the screen. I'm thinking of a bubble canopy ... but, that's a "what if" that never happened. But, it's the first time I ever thought of a Vulture-powered Hurricane. Might have to relocate that little scoop in front of the windscreen if you're going to play fighter pilot.
Sort out the intake like a P-51A, clean up the lines from engine to tail like a Typhoon/Thunderbolt and make the cooling system like a P-51... It would be a great looking hot rod.
- Thread starter
- #38
wuzak
Captain
The Henley was used as an engine test bed by Rolls-Royce.
There is a great article on the Manchester in an Aircraft Illustrated Extra Number 10 called Bombers of World War II. The article is by J.R. Bushby. He describes flying in it and its flight characteristics on one engine - "Like an aerodynamic brick." He refused to go into the upper turret which was called, the "Botha Turret." He hints that the maximum bomb load was six thousand pounds on a raid to Hamburg in R5830. Due to engine overheating they dropped two one thousand pound bombs. Bushby concludes the article by saying that when flying the Manchester there was always in the back of the mind that something would go wrong.
The problem related to the big end bearing, the bearings at the crank shaft end of the connecting rods. I'm not sure how Rolls Royce did this: it could be a master conrod with the 3 other con rods connecting to it like in a radial or it could be a conrod with 3 con rods forks of wider width or a combination in between. Whatever it was it was said to be extremely complicated.
The other issue engine makers faced was crank shaft vibration. rigidity and harmonics. There was a lot alteration of firing order and crankshaft crank arm angles.
Even the Allison V-13420 had to have the two "V1710" engines displaced by 60 degrees as well as the firing order changed completely.
The approach Allison and to an extent Napier took seems to have been the right one. Allison took the V1710 and engineered a common crankcase that mated two V-1710 together to create the V-3420 with two separate shafts that were then joined by a gearbox. The approach taken by RR (broadly 4 Peregrine banks using a common crankshaft) creates huge problems in engineering the new crankshaft and its bearings and con rods. The approach taken by Daimler Benz with its DB601/DB606 was simply two separate engines clutched into a commo crankshaft. They shared a common central exhaust. This created all sorts of access and gearbox alignment problems as well as an hot exhaust to ignite any leaking oil.
Rolls Royce also had a political problem. Weight growth in the Manchester, caused by the Air Ministry and AVRO, required the vulture to operate at higher power levels for longer periods. Rolls-Royce simply couldn't point the finger back at Air Ministry or AVRO. Rather than a pointless finger pointing exercise and Rolls Royce simply took it on the chin and offered a sensible solution.: 4 merlins
