Westland Whirlwind alternative engines?

[wuzak]

However, the death of the Peregrine was part of the death of the double peregrine Vulture. To be fair to the decision makers, concentrating on the Merlin allowed worn out one to be used as raw material for Meteor tank engines when production of new Meteor parts were falling behind.

The Vulture was not a double Peregrine, and both were cancelled at the same time for the same reasons - not enough resources and only one type in production using each of them.

The failings of the Vulture were not the same as the failings of the Peregrine. If they shared any components it was probably only the pistons, maybe the valves and valve springs and possibly the valve rocker arms. The Bore spacings were different (6.1"for the Vulture, 5.625" for the Kestrel/Peregrine), so the blocks were different. The main problems for the Vulture were due to its X-layout and the master and slave rod arrangement - things thathad no effect on the Peregrine.

 

[Shortround6]

I still don't what the failings of the Peregrine were?

Keeping 2 squadrons in combat use 3 years after the engine went out of production doesn't sound like that bad of an engine. If it had been really troublesome you would think the effort of keeping it in service wasn't worth the results.

 

[wuzak]

I still don't what the failings of the Peregrine were?

I think they were having similar coolant sealing problems that plagued the single block/head Merlins until they were replaced by a two piece design.

 

[Edgar Brooks]

I still don't what the failings of the Peregrine were?.

Mostly it was its lack of performance at heights above 20,000'; it fell off, and, above 27,000' was considered quite poor, so much so that, even though it might, under favourable conditions, reach 30,000', the rate of climb over the last 4-5,000' dropped to 500' per minute.
With the 109F already regularly coming over above 22,000', the Whirlwind was viewed as verging on obsolescence, even before the end of 1940.
As early as May, 1940, Bulman said that the Peregrine was built in Derby, and could not be diverted to Crewe or Glasgow; Derby were also building the Vulture, Merlin X, Merlin XX, and the Griffon, and the Peregrine could only be continued at the detriment of those, with each engine costing two Merlins, or by postponing the Griffon, which was due to start in July, 1941.
It was also felt that uprating it to take 100 octane would basically require a new Mark of Peregrine.
It was the conversion to bomb-carrying that kept the Whirlwind in service for so long, but it was pointed out that the Hurricane, using only one engine, carried 50% more cannon ammunition for the same number of guns, and used a readily-available engine, which was also used by other aircraft, while the Peregrine had no other applications.
The Whirlwind also used 50% more materials to perform (fighting) tasks less well than the Spitfire; add in the impending arrival of the Typhoon, which, in 1941, was the great hope for the future, and the Whirlwind had no chance.
70 years on, it's easy to let hearts rule heads, but not when a nation is fighting for its very existence alone (apart from the considerable input from the Commonwealth, and escapees from occupied Europe, of course.)

 

[Shortround6]

The lack of altitude performance was a supercharger problem and one it shared with most other engines of it's time period. Critical altitude of the engine being 1,250ft less than the Merlin III. The Whirlwind as an aircraft was not going to give the altitude performance of the Spitfire using engines of equivalent supercharger performance because of weight and drag. It's altitude performance compared to the Hurricane might be much closer, using superchargers of equivalent supercharger performance.

The Whirlwinds problems are that it got behind in timing and apparently, nobody had the faith in it to push it through in 1938-39-very early 1940. The same rather applies to the Peregrine engines. There is no reason that a Peregrine, if made on equivalent tooling should take as much effort to build as two Merlins. If it was being made in small batches (and it was or in a trickle) without proper jigs and fixtures/tooling that the Merlin had, then I see no reason not to believe that it took much more time/effort to build one Peregrine, but that is not a fault of the basic engine design.
TO use 100 octane to it's fullest extent would certainly require a new mark but then the Merlin went through many marks too, in order to fully use the new fuel/s.

There are at least 3 sources I have found that mention 100 octane fuel in the Peregrine. Unfortunately Lumsden's book, while giving boost levels and RPM for the Peregrine for both 87 and 100 octane fuel doesn't give most of the corresponding power outputs. It does give 880 hp for take off using 9lbs boost though and gives 9lbs boost as the limit at 3000rpm at altitude not given and power not given, also 9lbs boost at 2850rpm for climb or 1/2 hour rating. The 1945 edition of "Aircraft engines of the World" 765hp at 3000rpm at 43.7in (6.75lbs? boost). 960hp/3000rpm at 12,000ft, military and 860hp/2850rpm at 13,500ft. manifold pressure not given. These would seem to be consistent with 775hp rating for take off at 6/75lbs in other books and the 880hp at 15,000ft rating using 6-6.75lbs boost.
Just like the Merlin III, there is no gain in performance at altitude to be had using 100 octane fuel without a new supercharger. But like the Merlin III, it appears that a new mark of engine was not needed in order to get some performance boost form 100 octane fuel. The Hurricane got a new supercharger in the fall of 1940 in order to try to keep in competitive as a fighter. The Spitfire had a new supercharger in service by the Spring of 1941.

The Hurricane carried 50% more ammo because the Whirlwind was never changed to belt feed guns. There were at least 2 if not 3 different four 20mm gun arrangements tried on Whirlwinds using belt feeds but none were approved for use (refit?) as the plane was either out of production or already canceled. The belt feed Whirlwinds carried approximately 33% more ammo than the Hurricane as well it should seeing as how it had several hundred more horsepower.

In the long run stopping the Whirlwind and the Peregrine were the right things to do but there seems to be a bit of a smokescreen as to exactly why and when.

 

[wuzak]

I think that, when it all comes down to it, Rolls-ROyce didn't feel they had the time or resources to develop the myriad engine designs it had at the start of the war. While the Peregrine's problems may have been solved relatively quickly the thought may have been that it was of limited usefulness as the Merlin was available and already been used in many types. Then there was the push to increase the performance of the Merlin - how much would that have been affected if there was aparallel program on the Peregrine as well as the Griffon? Or would the Griffon program have suffered?

On the supercharger issue, I wonder if the Peregrine could have used the Merlin 61 supercharger - or would it be too big?

I would think an rpm increase would be necessary - the Vulture was designed for 3200rpm, though the Peregrine, with the same stroke, had a maximum of 3000rpm.

 

[Edgar Brooks]

The lack of altitude performance was a supercharger problem and one it shared with most other engines of it's time period. Critical altitude of the engine being 1,250ft less than the Merlin III. The Whirlwind as an aircraft was not going to give the altitude performance of the Spitfire using engines of equivalent supercharger performance because of weight and drag. It's altitude performance compared to the Hurricane might be much closer, using superchargers of equivalent supercharger performance..

But it wasn't altitude performance that was needed; Dowding said that he might be glad of all the Whirlwinds that he could get, because, in 1940, it was the only aircraft that had the firepower to deal with tanks, in the event of the expected invasion. He kept the Whirlwinds out of the BoB, for that reason, and because there were only a few serviceable airframes. When the threat of invasion receded, the Hurricane (which had been planned to end in May, 1941) was found to be capable, with the Merlin XX, of doing anything that the Whirlwind could do.

The Whirlwinds problems are that it got behind in timing and apparently, nobody had the faith in it to push it through in 1938-39-very early 1940.

A lot of that was due to the then-held idea that twin engined fighters needed counter-rotating engines, which, at that time, meant totally different components (the Hornet made use of an extra gear, in the train, to achieve this post-war, but that wasn't feasible, then.) The prototype Whirlwind had this feature, but it was found to be a false premise, so was dropped, leaving R-R to produce just the single type of engine, but already delayed.

There is no reason that a Peregrine, if made on equivalent tooling should take as much effort to build as two Merlins. If it was being made in small batches (and it was or in a trickle) without proper jigs and fixtures/tooling that the Merlin had, then I see no reason not to believe that it took much more time/effort to build one Peregrine, but that is not a fault of the basic engine design.

This is going to sound slightly rude, but isn't meant to; you're saying that, in 2012, you have a better idea of Rolls-Royce's capacity than the then-management, which is a fairly dangerous statement to make. R-R were already trying to get Ford to build their engines, and eventually needed Packard to build thousands of Merlins, starting with the 28 (a Packard version of the XX.)

TO use 100 octane to it's fullest extent would certainly require a new mark but then the Merlin went through many marks too, in order to fully use the new fuel/s.

But the Merlin had many uses, while the Peregrine had only one, which was an obsolete airframe.

There are at least 3 sources I have found that mention 100 octane fuel in the Peregrine. Unfortunately Lumsden's book, while giving boost levels and RPM for the Peregrine for both 87 and 100 octane fuel doesn't give most of the corresponding power outputs. It does give 880 hp for take off using 9lbs boost though and gives 9lbs boost as the limit at 3000rpm at altitude not given and power not given, also 9lbs boost at 2850rpm for climb or 1/2 hour rating. The 1945 edition of "Aircraft engines of the World" 765hp at 3000rpm at 43.7in (6.75lbs? boost). 960hp/3000rpm at 12,000ft, military and 860hp/2850rpm at 13,500ft. manifold pressure not given. These would seem to be consistent with 775hp rating for take off at 6/75lbs in other books and the 880hp at 15,000ft rating using 6-6.75lbs boost.

The Peregrine could use 100, at higher boost levels, but only in short bursts, measured in seconds, which damaged the engine.

In the long run stopping the Whirlwind and the Peregrine were the right things to do but there seems to be a bit of a smokescreen as to exactly why and when

These conspiracy theories are all very fine, but fall down on one fundamental point; Westland built just over 100 Whirlwinds, for which no use could be found after 1940 (until it was converted to carry bombs,) but built over 1600 Spitfires and Seafires, and were still invited to tender for (and build) other aircraft. This hardly sounds like an attempt to damage the company, which is what others have alleged. Times without number, I have to point out that files in our National Archives have a minimum closure time of 30 years, so anyone trying to find information, on the Whirlwind story, has had to wait until 1975+; the files are there, I've read them, and the decisions were taken quite openly, with no conspiracies involved.

 

[wuzak]

A lot of that was due to the then-held idea that twin engined fighters needed counter-rotating engines, which, at that time, meant totally different components (the Hornet made use of an extra gear, in the train, to achieve this post-war, but that wasn't feasible, then.)

Why wasn't it feasible then? It was just an idler gear between the two that were alreay there. Surely not beyond Rolls-Royce's ability?

Was it a widely held belief? What other twins were designed with this in mind? Certainly no radial twins had counter-rotating props.

The prototype Whirlwind had this feature, but it was found to be a false premise, so was dropped, leaving R-R to produce just the single type of engine, but already delayed.

So, how was the counter-rotating props achieved? Reversing the engine?

My thought is that the Whirlwind was designed around two same rotating engines, but one was evaluated with counter-rotating props, which was found to make no difference to the pilots.

 

[Edgar Brooks]

Or would the Griffon program have suffered?.

I already noted that R-R said that the programme would probably have to be delayed.

On the supercharger issue, I wonder if the Peregrine could have used the Merlin 61 supercharger - or would it be too big?

The Peregrine had a downdraft carburettor intake, and the 61's blower needed an intercooler, and thus extra radiators, not easy in a small airframe.

I would think an rpm increase would be necessary - the Vulture was designed for 3200rpm, though the Peregrine, with the same stroke, had a maximum of 3000rpm

The Merlin was limited to 3000 rpm, so it's doubtful that would have been possible by any more than a very small %age.

 

[Edgar Brooks]

Why wasn't it feasible then? It was just an idler gear between the two that were alreay there. Surely not beyond Rolls-Royce's ability?
Was it a widely held belief? What other twins were designed with this in mind? Certainly no radial twins had counter-rotating props..

You're using 20:20 hindsight, again. R-R, in 1935, thought it necessary; for their reasons, you'll need to ask Rolls-Royce Heritage Trust. According to the Air Ministry, it was a French theory, prevalent at the time. The Hornet's Merlins used an idler gear, the Peregrines didn't; they were built as "handed" engines, for reasons known to R-R, but not me.

So, how was the counter-rotating props achieved? Reversing the engine?

I've no idea; "handed" doesn't really give us the definitive answer, but I would suspect reversing was the answer.

My thought is that the Whirlwind was designed around two same rotating engines, but one was evaluated with counter-rotating props, which was found to make no difference to the pilots

It was the other way round (pardon the pun); the prototype had handed engines, while the second prototype didn't, and it was then that it was found to make no difference.

 

[wuzak]

I've no idea; "handed" doesn't really give us the definitive answer, but I would suspect reversing was the answer.

Even if the engine was "reversed" Rolls-Royce would still have needed to make at least one extra idler gear - because it was unlikely that they would go to the trouble of making opposite hand superchargers, magnetos, etc.

Left handed V-1710s have the crank rotate in the opposite direction to right handed engines, but the supercharger stil rotates in the same direction.

 

[Edgar Brooks]

Even if the engine was "reversed" Rolls-Royce would still have needed to make at least one extra idler gear - because it was unlikely that they would go to the trouble of making opposite hand superchargers, magnetos, etc..

Rolls-Royce's chief designer doesn't agree with you, and I quote,""For this installation it was decided to hand all the engine components necessary to provide reverse rotation. This was a considerable complication and was abandoned on future engines. This experience led to the use of a special reduction gear for the Merlin engines used in the de Havilland Hornet aircraft in which an idler gear was introduced to obtain reverse rotation of the propeller, leaving other engine components unaltered."

 

[wuzak]

Rolls-Royce's chief designer doesn't agree with you, and I quote,""For this installation it was decided to hand all the engine components necessary to provide reverse rotation. This was a considerable complication and was abandoned on future engines. This experience led to the use of a special reduction gear for the Merlin engines used in the de Havilland Hornet aircraft in which an idler gear was introduced to obtain reverse rotation of the propeller, leaving other engine components unaltered."

Jeez, they must have had plenty of time on their hands at the time....

 

[Edgar Brooks]

Jeez, they must have had plenty of time on their hands at the time....

Plans tenders were made in 1936, with construction of the 1st. prototype started mid-1937, so there was no war on, and still hopes that it wouldn't happen.
Rolls-Royce, before they went bust around 1970, were a byword for perfectionism; we were told, during the 1950s, how a man, touring in Spain, had the back axle of his R-R (dont know the marque) break, so he contacted R-R, who flew two men out to Spain, with a spare axle, which they fitted, allowing the tour to continue. When the man got home, he waited (and waited) for the bill, but received nothing. Eventually he contacted the company, direct, and asked about his bill, to be told,"Sir, Rolls-Royce cars do not break down."

 

[Airframes]

Still true, to an extent, today. Last year (and not the first time seen), I saw a Roll Royce, obviously immobile, being loaded onto a curtain-sided recovery trailer, presumably to be taken to a garage for repair. Once loaded, the curtains were drawn, just as on a large articulated wagon, hiding the entire car from view. Obviously, Rolls Royce did not want one of their 'creations' being seen to have been recovered after breakdown - because Rolls Royce' "do not break down....".

 

[Shortround6]

But it wasn't altitude performance that was needed; Dowding said that he might be glad of all the Whirlwinds that he could get, because, in 1940, it was the only aircraft that had the firepower to deal with tanks, in the event of the expected invasion. He kept the Whirlwinds out of the BoB, for that reason, and because there were only a few serviceable airframes. When the threat of invasion receded, the Hurricane (which had been planned to end in May, 1941) was found to be capable, with the Merlin XX, of doing anything that the Whirlwind could do.

This is part of what I mean about a smoke screen, in your post #24 you talked about the lack of high altitude performance in the fall winter of 1940/41 and the Whirlwinds inability to combat the 109F at 22,000ft and above, no you are saying it was viewed as an anti-tank aircraft and altitude performance was needed just a few months before that. Which is it?

This is going to sound slightly rude, but isn't meant to; you're saying that, in 2012, you have a better idea of Rolls-Royce's capacity than the then-management, which is a fairly dangerous statement to make. R-R were already trying to get Ford to build their engines, and eventually needed Packard to build thousands of Merlins, starting with the 28 (a Packard version of the XX.)

Actually, it sounds a lot rude. Perhaps I didn't say it well but I thought I tried to give an explantion as to why a 1296cu in V-12 engine "cost" twice as much as a 1650cu in V-12 engine when both shared almost the same details (valves per cylinder, over head cams and so on) when it flies in the face of common sense. As an example, say R-R had two machines performing similar operations on connecting rods. One machine is making Merlin rods continuously. the other is making Peregrine rods and Merlin rods in alternating batches. Not only do you loose the production of Merlin rods while making the Peregrine rods but every time the machine is changed over (tool holders, part fixtures/clamps, etc) you loose production of the Merlin rods. Multiply that times the thousands of parts and some of the parts taking dozens of operations and I can understand that every Peregrine could cost the production of two Merlins, but it doesn't mean the Peregrine actual cost ( in money) twice what a Merlin did and it doesn't mean that the Peregrine was actually twice as hard as the Merlin to make. It does speak to the capacity of Rolls-Royce in manufacturing terms.

But the Merlin had many uses, while the Peregrine had only one, which was an obsolete airframe.

The Whirlwinds airframe was obsolete when? In 1940? In 1941?

The Peregrine could use 100, at higher boost levels, but only in short bursts, measured in seconds, which damaged the engine.

Care to give a source for this? In Victor Bingham's book on the Whirlwind he copies what I believe are the pilots notes and part of the take of procedure is to run each engine (one at a time) up to 2950/3000rpm and 9lbs of boost to check the supercharger boost limit. If the engine was damaged in in seconds doing this it seems it would be a very foolish thing to do before each and every flight? perhaps the procedure was changed at a later date?

These conspiracy theories are all very fine, but fall down on one fundamental point; Westland built just over 100 Whirlwinds, for which no use could be found after 1940 (until it was converted to carry bombs,) but built over 1600 Spitfires and Seafires, and were still invited to tender for (and build) other aircraft. This hardly sounds like an attempt to damage the company, which is what others have alleged. Times without number, I have to point out that files in our National Archives have a minimum closure time of 30 years, so anyone trying to find information, on the Whirlwind story, has had to wait until 1975+; the files are there, I've read them, and the decisions were taken quite openly, with no conspiracies involved.

I don't think there was a conspiracy, more like a comedy of errors which some people then tried to sweep under the rug. Somebody must have thought the Whirlwind was good for something or they wouldn't have kept it around for as long as they did. Maybe it was the lack of a rear seat limiting it's ability to be turned into a target tug that kept in the front line so long

The Bombs were not added until 1942 and then, as the story goes, at the instigation of the using squadron/s. In any case keeping 2 squadrons around for over a year before getting around to putting the bombs on them certainly doesn't sound like no use.

As I said before, stopping the program was the right decision, it is just that too many of the excuses don't hold water.

 

[wuzak]

The Peregrine had a downdraft carburettor intake, and the 61's blower needed an intercooler, and thus extra radiators, not easy in a small airframe.

I said nothing about the airframe. Just wondering if the Merlin 61 supercharger could have worked on the Peregrine. The 130/131s on the Hornet also had downdraft carbies, so that was certainly possible.

If RR were going to adapt the Merlin 61 supercharger to the Peregrine I dare say t is because they had more roles for it than just the Whirlwind.

The Merlin was limited to 3000 rpm, so it's doubtful that would have been possible by any more than a very small %age.

For the same piston speed as a Merlin at 3000rpm the Peregrine would get nearly 3300rpm (3275rpm in fact).

For an equivalent piston speed to a Griffon 65 the Peregrine would be at 3300rpm.

 

[wuzak]

SR, at the end of the day the Peregrine was a victim of rationalisation. As was the Vulture and the Exe.

 

[tomo pauk]

What benefits, if any, would be achieved by mating with Peregrine and superchargers from Merlin X, or XX? Something akin what was done for Merlin (from Vulture?) or for DB-605 (from 603)?

 

[wuzak]

Ok, here's some numbers for a Peregrine to a hypothetical "RP.17SM" (equivalent to the Merlin's RM.17SM, and using that engine's performance as a basis fo the calculations).

There are three RM.17SM states I based the numbers on:
1. Max tested: 2620hp @ 3150rpm -> 2755kPa BMEP and 16.0m/s piston speed
2. Accidental sprint test: 2380hp @ 3300rpm -> 2389kPa and 16.76m/s.
3. RM.17SM rated power: 2200hp @ 3000rpm -> 2429kPa, 15.24m/s.

Considering the BMEPs with a 3000rpm limit for the Peregrine RP.17SM:
1. 1961hp
2. 1700hp
3. 1729hp

Considering the BMEPs and piston speed:
1: 2246hp @ 3436rpm
2: 2040hp @ 3600rpm
3: 1886hp @ 3273rpm

Of course had Rolls-Royce been developing the Merlin, the Griffon and the Peregrine it is unlikely that the Merlin woudl have got to the RM.17SM stage, let alone the Peregrine getting to "RP.17SM".