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Estimating the performance of supercharged piston aero engines


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#51 gruntguru

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Posted 26 September 2011 - 00:25

Griffon Spits were a high performance aircraft, but everyone that flew one said the eary Spit was an infinitely sweeter plane to fly. The Battle of Britain Spitfire was the right machine at the right time. The only problem was Britain's capacity to build them and train pilots to fly them.

I recall one of the military aviation magazines years ago did a feature on "Best Fighter of all time". The Mustang won it (range was the decider) with Spitfire second. Interesting that 1st and 2nd place were both liquid cooled. (Both Merlins of course)

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#52 Vanishing Point

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Posted 26 September 2011 - 01:25

Griffon Spits were a high performance aircraft, but everyone that flew one said the eary Spit was an infinitely sweeter plane to fly. The Battle of Britain Spitfire was the right machine at the right time. The only problem was Britain's capacity to build them and train pilots to fly them.

I recall one of the military aviation magazines years ago did a feature on "Best Fighter of all time". The Mustang won it (range was the decider) with Spitfire second. Interesting that 1st and 2nd place were both liquid cooled. (Both Merlins of course)


But would they have been as keen on the early Spit if they'd have had a Dora 9 on their tail and there's also a lot of similar garbage out there based on the idea that the Hurricane was better than the Spit because it shot down more aircraft (Bombers).Probably only because the Spits were keeping the 109's from getting them :lol: and would any pilot realistically have complained during the invasion of Belgium and France if they'd have had Griffon Spits instead of what they had.

But I wonder if the ones who voted for the Mustang knew the history of this group who chose to keep their Thunderbolts when offered Mustangs.

http://en.wikipedia....h_Fighter_Group

Edited by Vanishing Point, 26 September 2011 - 01:39.


#53 gruntguru

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Posted 26 September 2011 - 01:35

I am sure that a pilots chances of making kills would be better in the Jug due to its higher performance. Likewise his chances of survival.

On the other hand if a Thunderbolt and a Mustang had to "dogfight to the death" which would win? Maybe the Jug due to superior armour? What about a duel to the first "hit". My money would be on the Mustang - and certainly a Spitfire.

#54 Vanishing Point

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Posted 26 September 2011 - 01:55

I am sure that a pilots chances of making kills would be better in the Jug due to its higher performance. Likewise his chances of survival.

On the other hand if a Thunderbolt and a Mustang had to "dogfight to the death" which would win? Maybe the Jug due to superior armour? What about a duel to the first "hit". My money would be on the Mustang - and certainly a Spitfire.


Probably true with a Mk IX or XIV but the T bolt certainly seemed to be a better idea than the 24 cylinder Typhoon/Tempest at higher levels and could still do a good job against ground targets.But the early marks of Spit at the time of the invasion of France and Battle of Britain no chance.Which is the hypothetical point I was making as a what if comparison as to wether Rolls were right to drop the Vulture project to (rightly) concentrate on development of the improved Merlin and the Griffon which unfortunately all came too late to make a difference at the beginning.


#55 Kelpiecross

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Posted 26 September 2011 - 03:33

Probably true with a Mk IX or XIV but the T bolt certainly seemed to be a better idea than the 24 cylinder Typhoon/Tempest at higher levels and could still do a good job against ground targets.But the early marks of Spit at the time of the invasion of France and Battle of Britain no chance.Which is the hypothetical point I was making as a what if comparison as to wether Rolls were right to drop the Vulture project to (rightly) concentrate on development of the improved Merlin and the Griffon which unfortunately all came too late to make a difference at the beginning.


Nobody seems to have mentioned the Mk. VIII Spitfire which is probably the best of the Merlin Spits and maybe the best Spitfire of all.

This whole discussion is very interesting but is relying hugely on hindsight. As GG points out (I think) the RAF was lucky to have something as good as the Spitfire at the time of the BoB. They might have had to rely on Furies and Gladiators.

You could take hypothethising to extremes and suggest that the RAF could have had a jet-powered fighter ready for the BoB.

There is not much point in speculating what could have been.



#56 Wuzak

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Posted 26 September 2011 - 04:23

Nobody seems to have mentioned the Mk. VIII Spitfire which is probably the best of the Merlin Spits and maybe the best Spitfire of all.

This whole discussion is very interesting but is relying hugely on hindsight. As GG points out (I think) the RAF was lucky to have something as good as the Spitfire at the time of the BoB. They might have had to rely on Furies and Gladiators.

You could take hypothethising to extremes and suggest that the RAF could have had a jet-powered fighter ready for the BoB.

There is not much point in speculating what could have been.



Yes, the Mk VIII was the definitive two stage Merlin Spitfire, while the IX was an interim model based on the V. And, IMO, the prettiest of the Spiftires.

In 1940 there is little doubt which the two best fighters were in the world - the Spitfire and the Bf109E.

If the Mustang airframe had been around in time for the Battle of Britain with the less powerful single stage Merlin and lower octane fuel (PN100 introduced 1939/1940) it would not have been as suitable for the task as the Spitfire. Simply because the Spitfire was asked to climb to fighting altitude with a few minutes notice before the enemy arrived. The Jug would have no chance at getting to the altitude required in the time.

#57 Wuzak

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Posted 26 September 2011 - 04:29

Probably true with a Mk IX or XIV but the T bolt certainly seemed to be a better idea than the 24 cylinder Typhoon/Tempest at higher levels and could still do a good job against ground targets.But the early marks of Spit at the time of the invasion of France and Battle of Britain no chance.Which is the hypothetical point I was making as a what if comparison as to wether Rolls were right to drop the Vulture project to (rightly) concentrate on development of the improved Merlin and the Griffon which unfortunately all came too late to make a difference at the beginning.


The Tornado/Typhoon was intended to replace the Spitfire. But with the cancellation of the Vulture and continuing problems with the Sabre, and the very thick wing of the Typhoon causing problems with compressibility, it could not. And as the Spitfire improved with the Merlin the high altitude fighter role was taken, and it was less necessary to develop the Tempest in that way. Napiers had been experimenting with a 3 speed 2 stage supercharger for the Sabre, but this was canned during the English Electric takeover as it was wasting resources better spent on getting production sorted. If the need for a high altitude version had been required it would have been made.



#58 Wuzak

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Posted 26 September 2011 - 04:36

Back to the original topic....

RRHT have provided the power for maximum climb (30 minute limit) and maximum continuous power, so can we estimate the power in the weak cruise condition?

The Vulture had 24 cylinders with a bore of 5in and a stroke of 5.5in.

The Data from previous posts:

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

Because of the issues the Vulture was having with reliability the operating limits for the engine were given as:
Max climb - 30 minutes at 2850rpm, +6psi boost
Cruise in auto weak - continuous at 2600rpm, +2psi boost.



The full throttle heights for the Vulture were 4000ft in Moderate Supercharge (MS) gear and 13,500ft in Full Supercharge (FS) gear. The gear ratios for the supercharger were 5.5 (MS) and 7.3 (FS).

Ratings and fuel consumption figures for teh Vulture II and Merlin XX, using 100 octane fuel, were:

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

Merlin XX
(MS gear):
Max t/o (SL) - 1280bhp, 3000rpm, 12lb boost, 0.64-0.71 pt/bhp/hr;
Max climb - 1220bhp, 2850rpm, 9lb boost, 0.57-0.63 pt/bhp/hr;
Max cruise - 1080bhp, 2650rpm, 7lb boost, 0.54-0.59 pt/bhp/hr
(FS gear):
Max climb - 1130bhp, 2850rpm, 9lb boost, 0.63-0.70 pt/bhp/hr;
Max cruise - 1015bhp, 2650rpm, 7lb boost, 0.57-0.64 pt/bhp/hr


So, estimating the fuel density at 0.75kg/l I get the specific fuel consumption figures:

Vulture II

bhp lb/hp/hr   g/kW/hr
Max T/O		 1800	0.677	 411.3
Max Climb (MS)  1700	0.630	 383.1
Max Climb (FS)  1455	0.695	 422.5
Max Cruise (MS) 1480	0.573	 348.5
Max Cruise (FS) 1290	0.620	 377.1

Merlin XX (low fuel consumption number)
bhp lb/hp/hr   g/kW/hr
Max T/O		 1280	0.601	 365.6
Max Climb (MS)  1220	0.536	 325.6
Max Climb (FS)  1130	0.592	 359.9
Max Cruise (MS) 1080	0.507	 308.5
Max Cruise (FS) 1015	0.536	 325.6

Merlin XX (high fuel consumption number)
bhp lb/hp/hr   g/kW/hr
Max T/O		 1280	0.667	 405.6
Max Climb (MS)  1220	0.592	 359.9
Max Climb (FS)  1130	0.658	 399.9
Max Cruise (MS) 1080	0.554	 337.1
Max Cruise (FS) 1015	0.601	 365.6



#59 Vanishing Point

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Posted 26 September 2011 - 12:38

Nobody seems to have mentioned the Mk. VIII Spitfire which is probably the best of the Merlin Spits and maybe the best Spitfire of all.

This whole discussion is very interesting but is relying hugely on hindsight. As GG points out (I think) the RAF was lucky to have something as good as the Spitfire at the time of the BoB. They might have had to rely on Furies and Gladiators.

You could take hypothethising to extremes and suggest that the RAF could have had a jet-powered fighter ready for the BoB.

There is not much point in speculating what could have been.



The idea of hindsight and such an extreme hypothesis as Jet aircraft being available in 1940 during the invasion of France and the Battle of Britain isn't the same thing as just making a critical observation of what took place at the beginning of WW2.The idea of a force made up of upgraded Merlin MK IX/Griffon type Spits and Thunderbolts was probably do able based on the technology available at the time,'if' development and production capacity matched the rate of advance in technology that existed at Rolls and P and W, whereas the jet aircraft technology would have been a step too far.That lack of capacity can probably be blamed on the eventual Allies government's unpreparedness when all the warnings had been there.

Instead of which the RAF was lumbered with the early type underdeveloped Spits and even worse Hurricanes and the idea that they were lucky it wasn't Gladiators etc instead says it all. :eek: Although having said that there were probably some Hurricane pilots who were unfortunate enough to get involved with 109's who would think that what they had wasn't much better.

My view of what took place was that we had the wrong aircraft at the right time which 'almost' lost the war soon after it started and it was more by the luck,that Mitchell's original idea for the Spit was so good,than the judgement of the slow rate of development that followed his design's first stages,that the Battle of Britain was won after losing in France etc and the resources put into the Vulture project could only have made that worse and the same applies in regards to the Thunderbolt in that it's combination of ground attack abilities and the ability to fight it's way into and out of the scene would have made a big difference to the BEF's abilities to deal with the ground forces facing them.


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#60 gruntguru

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Posted 26 September 2011 - 13:11

The idea of a force made up of upgraded Merlin MK IX/Griffon type Spits and Thunderbolts was probably do able based on the technology available at the time,

Very debatable. For example - Merlin development was going nowhere until Hooker started at RR, spotted where the bottleneck lay and within months Merlin power output was up by 30%. Wouldn't have happened without Hooker. You seem enamoured by the Griffon Spit - it was really something of a brute and had lost much of what made the Spit the great aircraft it was.

#61 Vanishing Point

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Posted 26 September 2011 - 15:12

Very debatable. For example - Merlin development was going nowhere until Hooker started at RR, spotted where the bottleneck lay and within months Merlin power output was up by 30%. Wouldn't have happened without Hooker. You seem enamoured by the Griffon Spit - it was really something of a brute and had lost much of what made the Spit the great aircraft it was.



If it was air superiority that they were going for then it's probably 'something of a brute' that was needed although the MK IX seems to have been well liked by those that used it too in that it was able to deal with the BMW FW 190 easily enough.

In which case the early type Me 109's,as used during the invasion of France and the Battle of Britain,or in fact probably any 109, would have been even easier for it to sort out.It seems obvious that in the type of war they were in at the beginning it was very high kill ratios that were needed but which were lacking and something with the performance of both the Mks IX and XIV could have made all the difference in stopping the Lutwaffe sooner rather than later and on the ground Thunderbolts against Panzer 111's and 1V's would probably have been a turkey shoot to match.

Something like a battle involving F15's,Tornadoes and F18's against Russian type equipment on the ground and in the air would have been in recent years probably.


#62 WPT

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Posted 26 September 2011 - 17:31

But I wonder if the ones who voted for the Mustang knew the history of this group who chose to keep their Thunderbolts when offered Mustangs.

Yes, the 56th FG was very good. The only FG in the 8th AF to end the war flying the P-47 (out of 15 FGs, which the other 14 FGs were flying the P-51). The first Merlin P-51 FG to GB was the 354th and was assigned to the 9th AF (tasked with the ground support mission). First mission of the 354th was on 1 Dec. 1943, many months after the 56th FG flew their first mission. The 354th ended the war with more air kills (704) than the 56th. At the end of 1944 the 354th were made to exchange their 51s for 47s. Pilots complained so much that after two months they were swtched back to the 51. Both planes were great and I'm glad we had both. WPT



#63 Vanishing Point

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Posted 26 September 2011 - 18:15

Yes, the 56th FG was very good. The only FG in the 8th AF to end the war flying the P-47 (out of 15 FGs, which the other 14 FGs were flying the P-51). The first Merlin P-51 FG to GB was the 354th and was assigned to the 9th AF (tasked with the ground support mission). First mission of the 354th was on 1 Dec. 1943, many months after the 56th FG flew their first mission. The 354th ended the war with more air kills (704) than the 56th. At the end of 1944 the 354th were made to exchange their 51s for 47s. Pilots complained so much that after two months they were swtched back to the 51. Both planes were great and I'm glad we had both. WPT


I'd already made the comment concerning the Mustang in that Goering said he knew the war was over when he saw the Mustangs over Berlin and many bomber crews owed their survival to it's long range escort fighter abilities.But the point I'm making is that there's the possibility that the war might have been over at it's beginning,using the technology available at that time.

For that the T bolt would possibly have had more of an advantage in available technology and ground attack capability and survivability.In the sense of it was no good losing aircraft and pilots to ground fire,wrecking liquid cooling systems,'if' there had been a fast,air cooled,radial powered,high and low level,multi role aircraft more suited to the job at the time.While the more advanced Spitfire types could have provided the air superiority fighter requirements in the theatre as it was during the battle for Belgium and France which was lost.All of which was a case of 'if only' development and production capacity,of engines and aircraft,had matched the pace of technological advance in engineering design during the late 1930's.


#64 Wuzak

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Posted 26 September 2011 - 22:44

You seem enamoured by the Griffon Spit - it was really something of a brute and had lost much of what made the Spit the great aircraft it was.



The XIV, and the XVIII derived from it (post war) handled very well in the air from what I have read. Getting them off the ground, on the other hand, was difficult.

The marks with the new, stronger wing - Mks 21, 22 & 24 - handled differently, particularly the 21 which had some bad traits that had to be sorted out.

The XIV was basically a VIII with a Griffon engine.



Very debatable. For example - Merlin development was going nowhere until Hooker started at RR, spotted where the bottleneck lay and within months Merlin power output was up by 30%. Wouldn't have happened without Hooker.


Hooker was one thing, another was fuel. At the start of the war the RAF mostly had 87 octane fuel. By the Battle of Britain they had upgraded to 100 octane fuel, and by late 1944 PN150 fuel was available. The higher octane fuels allowed for higher boost. In the Battle of Britain Spitfires were cleared for use with +12psi boost, by the end of the war they were using +25psi, and Merlins were cleared for +30psi at the end of the war.

When the Merlin was designed there is no way that RR engineers could have predicted in 1934, or even 1940, that the Merlin would in a few years go from 1000hp to over 2200hp.


#65 Wuzak

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Posted 26 September 2011 - 22:56

The idea of hindsight and such an extreme hypothesis as Jet aircraft being available in 1940 during the invasion of France and the Battle of Britain isn't the same thing as just making a critical observation of what took place at the beginning of WW2.The idea of a force made up of upgraded Merlin MK IX/Griffon type Spits and Thunderbolts was probably do able based on the technology available at the time,'if' development and production capacity matched the rate of advance in technology that existed at Rolls and P and W, whereas the jet aircraft technology would have been a step too far.That lack of capacity can probably be blamed on the eventual Allies government's unpreparedness when all the warnings had been there.

Instead of which the RAF was lumbered with the early type underdeveloped Spits and even worse Hurricanes and the idea that they were lucky it wasn't Gladiators etc instead says it all. :eek: Although having said that there were probably some Hurricane pilots who were unfortunate enough to get involved with 109's who would think that what they had wasn't much better.

My view of what took place was that we had the wrong aircraft at the right time which 'almost' lost the war soon after it started and it was more by the luck,that Mitchell's original idea for the Spit was so good,than the judgement of the slow rate of development that followed his design's first stages,that the Battle of Britain was won after losing in France etc and the resources put into the Vulture project could only have made that worse and the same applies in regards to the Thunderbolt in that it's combination of ground attack abilities and the ability to fight it's way into and out of the scene would have made a big difference to the BEF's abilities to deal with the ground forces facing them.



Sorry, but the RAF was re-equipping like mad. If they were unprepared they may have been left with Gladiators as their front line fighter aircraft. But instead they had Spitfires and Hurricanes.

The BoB would have been lost if it weren't for Hurricanes. For one thing it took a long time to get Spitfire production up and running, and there simply would not have been enough of them to go around.

If a Griffon Spit or P-47 was available in 1940 then I am sure it would have been. The Spitfire MkI and MkII were the state of the art British production fighter aircraft in 1940. State of the art in production in the US in 1940 was the P-36, and soon to be the P-40.

Also, in 1940 the P-47 was a lightweight fighter powered by an Allison V-1710. The R-2800 still undergoing development, and not having gone into production. The US remained officially neutral, and if it weren't for aircraft sales to Britain and France the US aviation industry may have been even more unprepared than they were. Also, FDR had committed more funds to new aircraft, weapons and factories around 1939-1940.

#66 Vanishing Point

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Posted 27 September 2011 - 00:17

The XIV, and the XVIII derived from it (post war) handled very well in the air from what I have read. Getting them off the ground, on the other hand, was difficult.

The marks with the new, stronger wing - Mks 21, 22 & 24 - handled differently, particularly the 21 which had some bad traits that had to be sorted out.

The XIV was basically a VIII with a Griffon engine.





Hooker was one thing, another was fuel. At the start of the war the RAF mostly had 87 octane fuel. By the Battle of Britain they had upgraded to 100 octane fuel, and by late 1944 PN150 fuel was available. The higher octane fuels allowed for higher boost. In the Battle of Britain Spitfires were cleared for use with +12psi boost, by the end of the war they were using +25psi, and Merlins were cleared for +30psi at the end of the war.

When the Merlin was designed there is no way that RR engineers could have predicted in 1934, or even 1940, that the Merlin would in a few years go from 1000hp to over 2200hp.


But the schneider type planes with Rolls R power,and that engine's rate of development together with the available fuel technology available at that time to fuel it,seems to suggest that the sate of the art was far in advance,by the mid 1930's,than the performance of the Merlin would suggest.The original ministry spec for modern fighteres,that the Spit was designed to meet, seemed way too conservative considering what would have been possible had Supermarine and Rolls been given carte blanche and a blank cheque to come up with something with similar performance to the Scneider racers and based on the R's capacity (which is what eventually happened anyway but all too late for the battle for France and Belgium),than the Merlin's which was a privately funded project at it's outset so obviously would have been subject to private funding type compromises.

The thing that needed to be predicted was possible war with Germany and most people knew it was coming at that time.What needed to be predicted therefore was that the performance requirements,set by the defence procurement departments at the time,were too conservative at the outset and the Merlin would probably need a lot of development work to bring it's power outputs up to the levels that something with the R's capacity could have provided and which was eventually proved by the Griffon.

It's also obvious that Rolls were thinking along the same lines because they did develop the original Griffon by de rating the R during the early 1930's.In which case the government obviously should have continued to fund Rolls to continue the project just as they did for the race planes.Which would probably have resulted in the eventual later Griffon design which probably would have been developed and in production in time for use in something like a Mk XIV type Spit during the late 1930's.Which all seems more logical to what actually happened with Hurricanes and low powered Spits losing the battle for France and Belgium and only just winning the Battle of Britain while Rolls had wasted valuable resources developing the (rightly) cancelled Vulture.

Edited by Vanishing Point, 27 September 2011 - 00:20.


#67 Vanishing Point

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Posted 27 September 2011 - 00:48

Sorry, but the RAF was re-equipping like mad. If they were unprepared they may have been left with Gladiators as their front line fighter aircraft. But instead they had Spitfires and Hurricanes.

The BoB would have been lost if it weren't for Hurricanes. For one thing it took a long time to get Spitfire production up and running, and there simply would not have been enough of them to go around.

If a Griffon Spit or P-47 was available in 1940 then I am sure it would have been. The Spitfire MkI and MkII were the state of the art British production fighter aircraft in 1940. State of the art in production in the US in 1940 was the P-36, and soon to be the P-40.

Also, in 1940 the P-47 was a lightweight fighter powered by an Allison V-1710. The R-2800 still undergoing development, and not having gone into production. The US remained officially neutral, and if it weren't for aircraft sales to Britain and France the US aviation industry may have been even more unprepared than they were. Also, FDR had committed more funds to new aircraft, weapons and factories around 1939-1940.


A lot of people don't realise just how close the Battle of Britain came to being lost because of the low kill ratio of fighter v fighter dogfights which really was caused by the closeness in performance between the Spit and the 109 and the usual results of what happened when Hurricanes met 109's.Not forgetting 303 machine guns which is why the later Spits had to be upgunned.But maybe the Battle of Britain would have been won easier if all Hurricane production at Hawkers was turned over to building Spitfires instead from 1936 on.


#68 Wuzak

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Posted 27 September 2011 - 02:06

The R was a racing engine based on the Buzzard. It had a double sided supercharger impeller and used a special brew of fuel concocted by Rod Banks. Funding for the 1929 Schneider Trophy race was by the government, but not for the 1931 race. Lady Houston stumped up teh cash, after which the government was shamed into contributing.

The R was good for 2300hp in the 1931 race. But at that power it literally lasted minutes before needing to be replaced. During development of the R the big end bearings failed, which led to a switch from fork and blade rods to a master and slave rod. The R weighed 1640lbs, roughly the same as a two stage Merlin.

In the early '30s a proposal to detune the R for military use was forwarded, the name Griffon being used for the engine. But it was discontinued.

The Peregrine, Merlin and Vulture formed Rolls-Royce's engine strategy in the 1930s. The Griffon wasn't a part of the strategy, but was started late at the behest of the Fleet Air Arm. The Griffon program benefitted greatly from the Merlin development, the result being a much tidier engine.

It is doubtful that had work on the Vulture (and Peregrine) been stopped earlier that the Griffon program would have been accelerated, or that the Merlin would have been improved faster.

When the Vulture and Peregrine were cancelled it was not a choice, but a necessity.

#69 Wuzak

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Posted 27 September 2011 - 02:11

A lot of people don't realise just how close the Battle of Britain came to being lost because of the low kill ratio of fighter v fighter dogfights which really was caused by the closeness in performance between the Spit and the 109 and the usual results of what happened when Hurricanes met 109's.Not forgetting 303 machine guns which is why the later Spits had to be upgunned.But maybe the Battle of Britain would have been won easier if all Hurricane production at Hawkers was turned over to building Spitfires instead from 1936 on.


The 20mm cannon was not widely available in 1940. Some BoB Spitfires were equipped with them, butthey were very unreliable in service.

There was a lot of trouble productionising the Spitfire, so the MAP was very wary of throwing all its eggs into that particular single basket. In fact, there was originally a thought that the Spitfire was to be cancelled after its initial production run (of 300 aircraft) in favour of its replacements - teh Tornado and Typhoon.

During the war as the Spitfire improved so did the Bf109.

#70 Kelpiecross

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Posted 27 September 2011 - 04:11

The 20mm cannon was not widely available in 1940. Some BoB Spitfires were equipped with them, butthey were very unreliable in service.

There was a lot of trouble productionising the Spitfire, so the MAP was very wary of throwing all its eggs into that particular single basket. In fact, there was originally a thought that the Spitfire was to be cancelled after its initial production run (of 300 aircraft) in favour of its replacements - teh Tornado and Typhoon.

During the war as the Spitfire improved so did the Bf109.


This discussion seems to be somewhat disparaging towards the Hurricane. From what I have read it was very much the equal of the 109 and Spitfire at lower altitudes (presumably up to about 20,000ft). I think its main problem was that it is a bit ugly compared to the Spit.

When I was a schoolboy in the early 1950's the 109 was always the Me109 not a Bf109. The official German designation might have been "Bf" but (I think) during the war and for many years after to English speakers it was an "Me".

I always feel that there is a hint of historical "revisionism" about "Bf".

Edited by Kelpiecross, 27 September 2011 - 04:12.


#71 Wuzak

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Posted 27 September 2011 - 05:09

This discussion seems to be somewhat disparaging towards the Hurricane. From what I have read it was very much the equal of the 109 and Spitfire at lower altitudes (presumably up to about 20,000ft). I think its main problem was that it is a bit ugly compared to the Spit.


The main problem with the Hurricane was that it was somewhat slower than the Spitfire with the same engine. Not sure that it was more competitive below 20k ft either.



When I was a schoolboy in the early 1950's the 109 was always the Me109 not a Bf109. The official German designation might have been "Bf" but (I think) during the war and for many years after to English speakers it was an "Me".

I always feel that there is a hint of historical "revisionism" about "Bf".


I do believe the early variants were Bf109s, named for Bayerische Flugzeugwerke for whom Messerschmitt worked as chief designer. In 1938 Messerschmitt took over BFW, which was then renamed Messerschmitt. I guess any aircraft which had a designation assigned to it before the takeover was Bf (as in Bf109, Bf110) and after that were Me (Me262, Me210, Me209).

#72 Vanishing Point

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Posted 27 September 2011 - 13:07

The development progression at Rolls from the R to the Merlin and then the Griffon just doesn't seem logical and seems to be more driven by cost than the need for an air superiority fighter which is what was needed.

The idea of the Hurricane being competitive with even the underpowered early versions of the Spit are more wishful thinking than realistic.It's level of inferiority and the resulting documented kill/losses ratios,in dogfights with the 109 were unacceptable and if Britain's total fighter force had been dependent on just the Hurricane,during the Battle of Britain,the result probably would have been similar to what happened in France.

The story of the British pereference of using .303 machine guns in fighters seemed to go along the lines of the powers that were thought that higher volumes of lower calibre rounds would be more effective than lower volumes of higher calibre rounds which seemed to be proved wrong in battle ?.Also based on the idea that the .303 was available produced locally whereas the .50 was only available as import from America ?.The Mustang and T bolt seemed to show that using multiple heavier calibre .50 machine guns was more effective than the .303 and as,if not more, effective than slower firing Cannons.

The Me 109 was developed but after the FW 190 was introduced it soon lost favour with it's pilots and those unlucky enough to still be using it called it the flying coffin especially in combat with the later marks of Spit,Mustangs,and Thunderbolts later in the war and that is probably just what they would have called it far sooner if only there had been Griffon Spits instead of Hurricanes during the Battle of France.

Edited by Vanishing Point, 27 September 2011 - 13:11.


#73 Wuzak

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Posted 27 September 2011 - 13:22

The Me 109 was developed but after the FW 190 was introduced it soon lost favour with it's pilots and those unlucky enough to still be using it called it the flying coffin especially in combat with the later marks of Spit,Mustangs,and Thunderbolts later in the war and that is probably just what they would have called it far sooner if only there had been Griffon Spits instead of Hurricanes during the Battle of France.



The Experten chose, mainly, to stick with the Bf109.

Britain and France were equipping their airforces with the best aircraft that they could build or buy. France even ordered P-36s....but they didn't arrive in sufficient numbers in time for teh Battle of France.



#74 Wuzak

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Posted 27 September 2011 - 13:32

The development progression at Rolls from the R to the Merlin and then the Griffon just doesn't seem logical and seems to be more driven by cost than the need for an air superiority fighter which is what was needed.


The engine companies, like Rolls-Royce, weren't developing engines for particular roles. The Merlin was a 1000hp class engine, the Vulture a 2000hp class engine and the Peregrine the baby brother at 800-900hp.

There is no direct link between the R and the Merlin or Griffon. What the R did was teach Rolls-Royce how to use boost.

The R was based on a 1920s design - the Buzzard, which was a 6/5 scale of the Kestrel. A development of the R would have been outdated by 1940.


The idea of the Hurricane being competitive with even the underpowered early versions of the Spit are more wishful thinking than realistic.It's level of inferiority and the resulting documented kill/losses ratios,in dogfights with the 109 were unacceptable and if Britain's total fighter force had been dependent on just the Hurricane,during the Battle of Britain,the result probably would have been similar to what happened in France.


But the RAF didn't have to rely on only Hurricanes, and the tactics used, or attempted, tried to use the strengths of the aircraft. In other words, the Hurricanes would attack the bombers while the Spitfires would attack the escort fighters.



The story of the British pereference of using .303 machine guns in fighters seemed to go along the lines of the powers that were thought that higher volumes of lower calibre rounds would be more effective than lower volumes of higher calibre rounds which seemed to be proved wrong in battle ?.Also based on the idea that the .303 was available produced locally whereas the .50 was only available as import from America ?.The Mustang and T bolt seemed to show that using multiple heavier calibre .50 machine guns was more effective than the .303 and as,if not more, effective than slower firing Cannons.


At the time of the Battle of Britain US aircarft tended to use only a pair of guns, or no more than 4. Often these would be 2 x 0.30s and 2 x 0.50s.

The RAF's plan was to replace the mgs with cannons. The Hispano cannon had a similar, if not greater, rate of fire as the US 0.50. But a lot heavier rounds.





#75 Vanishing Point

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Posted 27 September 2011 - 17:33

The engine companies, like Rolls-Royce, weren't developing engines for particular roles. The Merlin was a 1000hp class engine, the Vulture a 2000hp class engine and the Peregrine the baby brother at 800-900hp.

There is no direct link between the R and the Merlin or Griffon. What the R did was teach Rolls-Royce how to use boost.

The R was based on a 1920s design - the Buzzard, which was a 6/5 scale of the Kestrel. A development of the R would have been outdated by 1940.




But the RAF didn't have to rely on only Hurricanes, and the tactics used, or attempted, tried to use the strengths of the aircraft. In other words, the Hurricanes would attack the bombers while the Spitfires would attack the escort fighters.





At the time of the Battle of Britain US aircarft tended to use only a pair of guns, or no more than 4. Often these would be 2 x 0.30s and 2 x 0.50s.

The RAF's plan was to replace the mgs with cannons. The Hispano cannon had a similar, if not greater, rate of fire as the US 0.50. But a lot heavier rounds.



I knew that there was no direct link between the R and the eventual production type Griffon.But the connection I meant was the scope provided for development by keeping to that type of capacity rather than the starting point of power ouputs developed,as was the case with the early versions of the Merlin,and the eventual point at which you'll run out of scope for development to deliver reliable amounts of power,using an engine with a smaller capacity.Which might answer one of your previous questions concerning power all being about boost levels.The fact is wether it's naturally aspirated or forced induction there's no substitute for cubic inches.Which is why they came to the conclusion of putting the Griffon in the Spit instead of just leaving it with the Merlin throughout it's production life.

The fact that they weren't (or don't seem to have been) developing engines for particular roles would explain one of the reasons as to why we went to war to stop the Luftwaffe and Wehrmacht in France,with substandard aircraft,without the type of superiority in hardware,that was needed,especially considering the strength of the opposition.

The eventual Griffon can be seen as having more in common with the R than the Merlin considering the differences in capacity,and therefore scope for bigger power outputs,and there's no reason to think that what eventually became the Griffon wouldn't have all been possible by just using the same type of logical progression,which went into the Merlin,at the same time as development of the Merlin was taking place.

Meanwhile as of 1936 it was obvious that the Spitfire was going to be the better plane than the Hurricane in which case logic would have said stop the Hurricane's production and just concentrate on producing Spitfires using Hawker's production capacity together with Supermarine's and eventually Castle Bromwich,hopefully with Griffon power in time for coming battle in Belgium and France.It seems obvious that in that scenario the last thing they'd need is being sidetracked by development of the Vulture.

The issue of guns was already the subject of that type of discussion between small calibre versus larger calibre at the time and the fact is smaller calibre just wasn't up to the job.It would have been foreseeable at that time that using much too few larger calibre guns was likely to be just as bad as using more but with much too small a calibre.Logic would suggest to most engineers,even at that time,that you'd be throwing away the advantage of using .50's if you then used a lot less of them.A Griffon Spit using enough .50's would probably have been more effective than the 109's arrangement or even the Mk IX 's Cannon armament as the Mustang and T bolt proved.However fitting just 4 guns just shows how slow that the US was in getting it's act together in development and production,considering that the armament fitted to the Mustang and the T bolt wouldn't have just been a sudden brainwave thought up by someone with no prior idea that such an arangement was the way to do the job properly.

However in the battle in France and Belgium and even in the Battle of Britain many unfortunate Hurricane pilots didn't have the luxury of having a Spitfire in the vicinity when a 109 caught up with them.Whereas a force made up of just Spitfires would have been able to deal with both the bombers and the fighters better probably with fewer losses for more kills.

#76 gruntguru

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Posted 27 September 2011 - 23:05

I knew that there was no direct link between the R and the eventual production type Griffon.But the connection I meant was the scope provided for development by keeping to that type of capacity rather than the starting point of power ouputs developed,as was the case with the early versions of the Merlin,and the eventual point at which you'll run out of scope for development to deliver reliable amounts of power,using an engine with a smaller capacity.Which might answer one of your previous questions concerning power all being about boost levels.The fact is wether it's naturally aspirated or forced induction there's no substitute for cubic inches.Which is why they came to the conclusion of putting the Griffon in the Spit instead of just leaving it with the Merlin throughout it's production life.

The Merlin was designed to fit the "fighter" role as defined at the time, in terms of both power output and physical size and weight. The Hurricane and Spitfire were both designed for a "Merlin-size" engine - similar to the 109. When the Griffon was eventually installed in the Spitfire it was "shoehorned" in. There were a lot of compromises required, the most obvous (but probably the least detrimental) being the long "blisters" on the nose - just to get the thing to fit.

The fact that they weren't (or don't seem to have been) developing engines for particular roles would explain one of the reasons as to why we went to war to stop the Luftwaffe and Wehrmacht in France,with substandard aircraft,without the type of superiority in hardware,that was needed,especially considering the strength of the opposition.

They were in fact developing engines for particular roles. The reason they went to war with substandard aircraft is they were behind in the arms race. Germany knew they were going to war while Britain was hoping they weren't going to war.

Meanwhile as of 1936 it was obvious that the Spitfire was going to be the better plane than the Hurricane in which case logic would have said stop the Hurricane's production and just concentrate on producing Spitfires using Hawker's production capacity together with Supermarine's and eventually Castle Bromwich, hopefully with Griffon power in time for coming battle in Belgium and France.

To switch Hurricane factories to Spitfire production would have interrupted production and caused an enormous reduction in the number of available aircraft - at a time when aircraft numbers was the biggest problem by far - the RAF was massively outnumbered. Performance was not the problem. Meanwhile Spitfire production was being expanded at an astonishing rate. This rate of expansion would not have been possible if efforts were diverted to the task of converting Hurricane production to Spitfires. Of course Hawker was learning from the Hurricane production process too and disruption of that process would have detracted from efforts to get Typhoon andd Tempest into production.

Nobody anticipated any benefit in putting the Griffon in the Spit. When they finally did, the result was by no means the ultimate fighter. A Tempest with multi-stage supercharging would have been better all round.

The issue of guns was already the subject of that type of discussion between small calibre versus larger calibre at the time and the fact is smaller calibre just wasn't up to the job.It would have been foreseeable at that time that using much too few larger calibre guns was likely to be just as bad as using more but with much too small a calibre.Logic would suggest to most engineers,even at that time,that you'd be throwing away the advantage of using .50's if you then used a lot less of them.A Griffon Spit using enough .50's would probably have been more effective than the 109's arrangement or even the Mk IX 's Cannon armament as the Mustang and T bolt proved.However fitting just 4 guns just shows how slow that the US was in getting it's act together in development and production,considering that the armament fitted to the Mustang and the T bolt wouldn't have just been a sudden brainwave thought up by someone with no prior idea that such an arangement was the way to do the job properly.

All easier said than done. Fact is the armament simply wasn't available early on and fitment to thin Spitfire wings was another challenge.

However in the battle in France and Belgium and even in the Battle of Britain many unfortunate Hurricane pilots didn't have the luxury of having a Spitfire in the vicinity when a 109 caught up with them. Whereas a force made up of just Spitfires would have been able to deal with both the bombers and the fighters better probably with fewer losses for more kills.

It could not have been done, given the British government's failure to recognise the inevitability of war.

#77 Vanishing Point

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Posted 28 September 2011 - 00:55

The Merlin was designed to fit the "fighter" role as defined at the time, in terms of both power output and physical size and weight. The Hurricane and Spitfire were both designed for a "Merlin-size" engine - similar to the 109. When the Griffon was eventually installed in the Spitfire it was "shoehorned" in. There were a lot of compromises required, the most obvous (but probably the least detrimental) being the long "blisters" on the nose - just to get the thing to fit.


They were in fact developing engines for particular roles. The reason they went to war with substandard aircraft is they were behind in the arms race. Germany knew they were going to war while Britain was hoping they weren't going to war.


To switch Hurricane factories to Spitfire production would have interrupted production and caused an enormous reduction in the number of available aircraft - at a time when aircraft numbers was the biggest problem by far - the RAF was massively outnumbered. Performance was not the problem. Meanwhile Spitfire production was being expanded at an astonishing rate. This rate of expansion would not have been possible if efforts were diverted to the task of converting Hurricane production to Spitfires. Of course Hawker was learning from the Hurricane production process too and disruption of that process would have detracted from efforts to get Typhoon andd Tempest into production.

Nobody anticipated any benefit in putting the Griffon in the Spit. When they finally did, the result was by no means the ultimate fighter. A Tempest with multi-stage supercharging would have been better all round.


All easier said than done. Fact is the armament simply wasn't available early on and fitment to thin Spitfire wings was another challenge.


It could not have been done, given the British government's failure to recognise the inevitability of war.



The idea of the Griffon Spit was just like in car design where shoehorning a bigger engine in can make a much better faster product.A bit like putting the 427 ci engine in the Cobra,which was just a re engineering of the AC Ace which originally only ran with under 3.0 litre six cylinder power,amongst other examples.In this case the powers that were eventually realised that it was a much better and more practical idea than trying to stress the Vulture or Sabre 24 cylinder engine even more.

I know that the reason that we went to war with substandard planes was because we were behind in the arms race and the reason for that was probably because of those at the time who were putting up the same arguments then,as you are now,against those who were putting up the same arguments then,as I am now.

It's difficult to understand why shutting down production of the Hurricane after the first flight of the prototype Spitfire and putting Hawker's production capacity into joining Supermarine in building Spitfires instead would have led to production shortages in aircraft when it just would have meant exchanging one type of aircraft product for another better product instead.

On the subject of a hypothetical large timescale advance,in Spitfire Mk XIV production,it certainly would have been the ultimate fighter available at the time,if everyone had foreseen the benefits and it's difficult to believe that Mitchell and the designers who followed him wouldn't have foreseen those benefits if the government had given them carte blanche and a blank cheque to come up with that type of performance instead of the first underdeveloped versions based on the early Merlin.

On the subject of armament.It really wouldn't have been beyond the thinking of the quality of the designers at at the time to have re disigned the wings of the Spit to take much better armament than 8 303 machine guns far sooner than actually took place 'if' the ministry had instructed it.The reason for the original undergunning was more a flaw in the thinking of those doing the ordering than those doing the designing probably not helped by the issue of using a 27 Litre engine to do the job of one at least 10 Litres or so larger so it was a case of try to compromise for the lack of power by cutting down on drag.

There is another view concerning the mistaken idea that the government had failed to recognise the inevitability of war with Germany.They knew but they were playing for time having realised that their original ideas,concerning weapons requirements needed to face the strength of Germany's,were way underestimated,probably to save costs,and they needed time to rectify the mistake.That time ran out when the Germans realised what the British government was doing and then did exactly what everyone,who'd realised the problem,knew they would do,by invading Belgium and France before the British and the Americans got their acts together.The fall of France,and the following years of war in Europe,was probably the result.

http://www.historyof...fire_mkXIV.html

Edited by Vanishing Point, 28 September 2011 - 00:58.


#78 gruntguru

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Posted 28 September 2011 - 03:14

It's difficult to understand why shutting down production of the Hurricane after the first flight of the prototype Spitfire and putting Hawker's production capacity into joining Supermarine in building Spitfires instead would have led to production shortages in aircraft when it just would have meant exchanging one type of aircraft product for another better product instead.

Difficult for you maybe. Converting Hurricane production to Spits would have meant closing down a production line for months leading to a loss of production of hundreds of aircraft. In addition the Spitfire required 50% higher man-hours to produce so a further reduction in aircraft. The effort required to convert Hurricane production lines was better spent expanding Spitfire production elsewhere - which was happening. Finally, the Hurricane was arguably a better aircraft for shooting down bomber. It was a more stable gun platform, had a tighter turn radius and was easier to fly meaning less-experieced and less skilled pilots could be better utilised. In the end, Hurricanes destroyed 50% more enemy aircraft than did Spitfires during the BOB - largely of course due to the bomber-attack role they were assigned.

On the subject of a hypothetical large timescale advance,in Spitfire Mk XIV production,it certainly would have been the ultimate fighter available at the time,if everyone had foreseen the benefits and it's difficult to believe that Mitchell and the designers who followed him wouldn't have foreseen those benefits if the government had given them carte blanche and a blank cheque to come up with that type of performance instead of the first underdeveloped versions based on the early Merlin.

If Mitchell's original brief had been to design a fighter around the Griffon, he would not have designed the Spitfire - definitely not the Mk XIV. It was not possible at that time to forsee what the progression in fighter development would be.

#79 bigleagueslider

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Posted 28 September 2011 - 06:35

In the case of the 2800 it was one of the good ones and the comparison for the topic is with the 24 cylinder Napre and/or Sabre.In which case it's performance and reliability seem to have been good enough when fitted in the Corsair and Thunderbolt compared to the Vulture and most of the Sabre applications and even the Tempest was arguably a better plane when fitted with te Bristol Centaurus instead of the Sabre.I'd still stand by the idea that Rolls made the right decision in dropping the idea and the only thing is why did they and the government procurement departments leave it so long.Especially considering that it might have delayed the eventual introduction of the Griffon Spits.


In the US, Pratt & Whitney had a very active liquid-cooled sleeve valve engine effort under George Meade, in parallel with the air-cooled pushrod poppet valve radial engine effort under Luke Hobbs. The air-cooled radial engines progressed much faster, and Pratt wisely dropped their sleeve valve engine programs. By the end of the war, the fastest piston engine fighters were those powered by Pratt's R-4340.

In the UK, Rolls, Napier, and Bristol had sleeve valve engine programs. Under the pressure of the war effort, Rolls wisely dropped theirs. Napier carried on with their high-revving, liquid-cooled, sleeve valve Sabre, but its protracted development resulted in a limited impact on the war effort. Bristol stubbornly pursued development of their troublesome air-cooled, sleeve valve radials. And it bankrupted the company. Both Napier and Bristol's sleeve valve manufacturing was bailed out by access to US Sunstrand grinding machines.

Finally, the Rolls Merlin V12 was initially much better than the Allison V12 engine. But by the end of the war, the Allison V12 was as good as the Merlin, mostly due to its better fuel system and combustion chamber design.

Great discussion!
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#80 bigleagueslider

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Posted 28 September 2011 - 06:51

I know that the reason that we went to war with substandard planes was because we were behind in the arms race and the reason for that was probably because of those at the time who were putting up the same arguments then,as you are now,against those who were putting up the same arguments then,as I am now.

On the subject of a hypothetical large timescale advance,in Spitfire Mk XIV production,it certainly would have been the ultimate fighter available at the time,if everyone had foreseen the benefits and it's difficult to believe that Mitchell and the designers who followed him wouldn't have foreseen those benefits if the government had given them carte blanche and a blank cheque to come up with that type of performance instead of the first underdeveloped versions based on the early Merlin.


The UK Defense Ministry could have funded Whittle's turbine engine work in 1937 and had a viable jet fighter for the Battle of Britain.

As for the factors that determined what types of aircraft and engines the UK and the US each developed, it had mostly to do with how the aircraft were used. The Brits needed fast interceptors, with limited range. The US needed high altitude, long range escorts for the bombers.


#81 Wuzak

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Posted 28 September 2011 - 07:36

In the US, Pratt & Whitney had a very active liquid-cooled sleeve valve engine effort under George Meade, in parallel with the air-cooled pushrod poppet valve radial engine effort under Luke Hobbs. The air-cooled radial engines progressed much faster, and Pratt wisely dropped their sleeve valve engine programs. By the end of the war, the fastest piston engine fighters were those powered by Pratt's R-4340.

In the UK, Rolls, Napier, and Bristol had sleeve valve engine programs. Under the pressure of the war effort, Rolls wisely dropped theirs. Napier carried on with their high-revving, liquid-cooled, sleeve valve Sabre, but its protracted development resulted in a limited impact on the war effort. Bristol stubbornly pursued development of their troublesome air-cooled, sleeve valve radials. And it bankrupted the company. Both Napier and Bristol's sleeve valve manufacturing was bailed out by access to US Sunstrand grinding machines.

Finally, the Rolls Merlin V12 was initially much better than the Allison V12 engine. But by the end of the war, the Allison V12 was as good as the Merlin, mostly due to its better fuel system and combustion chamber design.

Great discussion!
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George Mead saw the Sabre in England, and set out to design his own on his return to the US. He used a different method of operating the sleeves, so as to not impinge on Napier's patents. His first effort was the X-1800 (XH-2600 military designation) which was longer, wider, taller and heavier than the Sabre, had about 400ci extra capacity and made less power. Then he went and designed the massive XH-3130 and XH-3730. But Mead fell ill, and others within the Pratt & Whitney organisation did not wish to continue the engine line. The R-2800 was a more mature engine project than the liquid cooled sleeve valve engines, it would have to be said.

The grinding machines that you speak of were diverted to Napiers, not Bristol. Bristol had figure out their production processes for sleeve valves years earlier. Napier's sleeve production problems were only solved when Bristol was ordered to assist Napiers - the Bristol Taurus had the same bore dimensions as the Sabre (ie 5in bore).

Rolls-Royce convereted a Kestrel in the late 1920s/early 1930s to use sleeve valves. One was tested as compression ignition (RR/D) and one as a petrol engine (RR/P). RR/P showed some promise. Rowledge designed the Exe while he was, IIRC, away from the company due to illness. The Exe was intended for use in naval aircraft, but its 1348ci/22.1l limited its scope for development, and its development was discontinued at the outbreak of war. Even so, at the time its 1200hp at over 4000rpm from its 24 cylinders compared favourably with the Merlin. It weighed somewhat more, though.

From around 1936/37 Rolls-Royce became involved with Ricardo's 2 stroke sleeve valve Diesel. That would evolve into the petrol injection Crecy program, which would continue throughout the war. The engine showed promise, but there were never enough resources to solve its issues n a timely fashion.

Late in the war Rolls-Royce designed two 24 cylinder sleeve valve engines - the Eagle 22 H24 and the Pennine X24. The Eagle flew in the Westland Wyvern, while the Pennine, which was intended for post war transports, only ever saw duty on the test bench. The Eagle was rated to over 3200hp, while the Pennine was rated to 2800hp - both from 2800ci. The Eagle 22 and Pennine were cancelled in favour of gas turbine development.

There are a few reasons for the Rolls-Royce Merlin's early superiority over the Allison V-1710. One was that Rolls-Royce were far more aggressive in their development - possibly the difference between the potential of being bombed and not. Also funding - in the 1930s the Allison program lacked the funds for faster development, while Rolls-Royce were well funded. Then there was the supercharger issue. At the start of the war the Merlin had very similar supercharger efficiencies to the V-1710's. Then Rolls-Royce employed Sir Stanley Hooker - and the efficiency of Rolls-Royce's superchargers improved markedly. Allison, and the other US manufacturers, used supercharger impellers designed by General Electric at the time, later changing to making their own.

I think you'll find that the fastest aircraft in WW2 were in the main powered by liquid cooled V-12s. The lightweight Mustangs (480mph+), Supermarine Spiteful (494mph), de Havilland Hornet (491mph prototype, 470mph+ production). The main exception was the experimental XP-47J, with high altitude turbocharger, revised aerodynamics and lighter weight it reportedly managed 500mph+, using the most powerful R-2800 of the war.

The only R-4360 fighter I can think of at the moment was the FG-2 - basically an F4U with an R-4360. It was faster at low altitude, but the regular version was faster higher up.

#82 Wuzak

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Posted 28 September 2011 - 07:45

The UK Defense Ministry could have funded Whittle's turbine engine work in 1937 and had a viable jet fighter for the Battle of Britain.

As for the factors that determined what types of aircraft and engines the UK and the US each developed, it had mostly to do with how the aircraft were used. The Brits needed fast interceptors, with limited range. The US needed high altitude, long range escorts for the bombers.


The US didn't know they needed a high altitude long range escort for the bombers until 1943. Up until the 8th AF began flying missions into Germany they fully believed in their theory that the well armed bomber flying in a formation for mutual defence would not need fighter escort. Also, it was not believed that such an aircraft could exist.

The plane that solved the problem did not owe anything to an official USAAF requirement. Instead it was the re-engined P-51. The P-51 came about because the British needed every aircarft it could lay its hands on. To that end, in 1940 the British Purchasing Commission approached North American seeking to set up another production line for P-40s. NAA said that they could build a better aircraft, and the BPC gave them a few months to come up with a prototype. The P-51A with the Allison engine lacked high altitude performance, but that changed when Rolls-Royce engineers plugged in a 60-series Merlin.

#83 Vanishing Point

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Posted 28 September 2011 - 16:08

Difficult for you maybe. Converting Hurricane production to Spits would have meant closing down a production line for months leading to a loss of production of hundreds of aircraft. In addition the Spitfire required 50% higher man-hours to produce so a further reduction in aircraft. The effort required to convert Hurricane production lines was better spent expanding Spitfire production elsewhere - which was happening. Finally, the Hurricane was arguably a better aircraft for shooting down bomber. It was a more stable gun platform, had a tighter turn radius and was easier to fly meaning less-experieced and less skilled pilots could be better utilised. In the end, Hurricanes destroyed 50% more enemy aircraft than did Spitfires during the BOB - largely of course due to the bomber-attack role they were assigned.


If Mitchell's original brief had been to design a fighter around the Griffon, he would not have designed the Spitfire - definitely not the Mk XIV. It was not possible at that time to forsee what the progression in fighter development would be.


The build methods of aircraft don't have production lines of the type which would have to close down before a change to the product being made.It would have just meant a re issuing of engineering drawings and different materials held in the works stores to match the schedules attached to the new/different drawings and those used for the design of the Spitfire instead of the Hurricane.If it was possible to set up the Castle Bromwich works from scratch then it would/should have been even easier to just change the production processes to match a different design brief at an existing aircraft manufacturing plant like Hawkers.

I've never heard of any pilots who flew Spitfires who ever thought that it wasn't easy enough to fly and who would have preferred to fly a Hurricane for that reason.


Spitfires v bombers (and unlike the Hurricane fighters too) no problem just ask the makers of the 1969 film Battle of Britain and a Griffon Spit wasn't/isn't exactly an unflyable cart horse either.


http://www.youtube.c...feature=related 3.32-5.37


http://www.youtube.c...feature=related 6.11-


http://www.youtube.c...feature=related


If Mitchell's brief had been to design a fighter around the Griffon it's my bet that he and Rolls would have done it all just as I've hypothesised.From the Schneider winners using the R to the Griffon XIV to the Spiteful.Just as the way it was eventually done except in this case those doing the ordering would have known what to order and wouldn't have been scared to spend a few bob doing it.

Edited by Vanishing Point, 28 September 2011 - 16:20.


#84 WPT

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Posted 28 September 2011 - 16:20

the fastest piston engine fighters were those powered by Pratt's R-4340.

Like Wuzak said, the R-4360 used in the FG-2 (a F4U built by Goodyear) was developed for low altitude intercept of Kamikaze. Top speed at altitude not as high as the ~445MPH of the F4U-4. Prodution of the R-4360 by the end of the war totaled ~135 units. Only ~20 FG-2s were built. The XP-47-J managed 505MPH. A P-51G (only two built) managed 495MPH and the P-51H (555 built, but too late for the war) managed 483MPH.
Have read RR had on the test bed during the war a Merlin on 150 fuel, 100"Hg, and ADI that produced 2640HP (maybe the 17.5SM?). What does anyone know about this? WPT



#85 Vanishing Point

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Posted 28 September 2011 - 21:36

Like Wuzak said, the R-4360 used in the FG-2 (a F4U built by Goodyear) was developed for low altitude intercept of Kamikaze. Top speed at altitude not as high as the ~445MPH of the F4U-4. Prodution of the R-4360 by the end of the war totaled ~135 units. Only ~20 FG-2s were built. The XP-47-J managed 505MPH. A P-51G (only two built) managed 495MPH and the P-51H (555 built, but too late for the war) managed 483MPH.
Have read RR had on the test bed during the war a Merlin on 150 fuel, 100"Hg, and ADI that produced 2640HP (maybe the 17.5SM?). What does anyone know about this? WPT



The idea of going for a specific output of around 100 hp per Litre,for a big WW2 aero engine,seems to defeat the object which was all about trying to get as much power,for as little stress,and therefore as much reliability,as possible.That type of test would probably have been looking for the limits not looking for a reliable viable specific power output ?.Most designs were working to a specific output of around 1 hp per ci which seems to have remained the benchmark throughout WW2 engine design and trying to push engines much past that was probably counterproductive for reliability in war conditions.After the war even the top air race teams reached the same conclusion as Mitchell and Rolls did in the Schneider racers that there is no substitute for cubic inches but going for too many cylinders just isn't a practical alternative either.


http://www.warbirdae...on/RedBaron.htm


http://en.wikipedia..../RB51_Red_Baron

Edited by Vanishing Point, 28 September 2011 - 21:57.


#86 gruntguru

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Posted 28 September 2011 - 23:08

If Mitchell's brief had been to design a fighter around the Griffon it's my bet that he and Rolls would have done it all just as I've hypothesised.From the Schneider winners using the R to the Griffon XIV to the Spiteful.Just as the way it was eventually done except in this case those doing the ordering would have known what to order and wouldn't have been scared to spend a few bob doing it.

Sorry - Mitchell started designing an aircraft in 1933 to use the Merlin engine. If he was designing for the Griffon it would have been a larger aircraft.

#87 gruntguru

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Posted 28 September 2011 - 23:30

I've never heard of any pilots who flew Spitfires who ever thought that it wasn't easy enough to fly and who would have preferred to fly a Hurricane for that reason.

Spitfires v bombers (and unlike the Hurricane fighters too) no problem just ask the makers of the 1969 film Battle of Britain and a Griffon Spit wasn't/isn't exactly an unflyable cart horse either.

The difference in kill rates and aircraft lost between Spitfires and Hurricanes during the BOB was not large. Sure the Spitfire was a much better aircraft but for every two Spitfires produced, they could build three Hurricanes and as I said previously, England's biggest problem during the BOB was shortage of fighters.

A quote from Alex Henshaw who flew more Spitfires than anybody and probably as skilfully as anyone.
"But I have to admit that the later marks, although they were faster than the earlier ones, were also much heavier and so did not handle so well. You did not have such positive control over them. One test of manoeuvrability was to throw her into a flick-roll and see how many times she rolled. With the Mark II or the Mark V one got two-and-a-half flick-rolls but the Mark IX was heavier and you got only one-and-a-half. With the later and still heavier versions, one got even less. The essence of aircraft design is compromise, and an improvement at one end of the performance envelope is rarely achieved without a deterioration somewhere else"

#88 Wuzak

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Posted 28 September 2011 - 23:41

Have read RR had on the test bed during the war a Merlin on 150 fuel, 100"Hg, and ADI that produced 2640HP (maybe the 17.5SM?). What does anyone know about this? WPT


In 1944 Rolls-Royce ran the experimental Merlin RM.17SM on the bench to a power of 2640hp @ 3150rpm, with +36psi boost using PN150 fuel with extra TEL and ADI (water injection). The power was later corrected to standard atmospheric conditions, 2620hp. The power was recorded during a 15 minute "sprint" test.

Note that Rolls-Royce buiilt Merlins did not use ADI during WW2. Some later Packard Merlins were fitted with ADI.

In July 1943 the RM.17SM, which was developed from a Mk66, ran a 15 minute test at 2380hp @ 3300rpm with +30psi boost, while an earlier test engine was accidentally run 2340hp @3300rpm and +30psi boost for 30 minutes during the high power portion of a 10 hour flight approval test.

The RM.17SM was rated at 2200hp @ 200ft and 2100hp @ 15,000ft using PN115/150 fuel. But the RM.17Sm never received a mark number.

The RM.17SM was part of the 100 series development program.

The RM.17SM used a different cam profile and different impeller sizes. The first stage impeller of the RM.17SM was 12.7" in diameter and the second stage 10.7". Earlier 2 stage Merlins (up to the 100 series) had a 12" first stage and 10.1" second stage.

#89 Wuzak

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Posted 28 September 2011 - 23:45

The difference in kill rates and aircraft lost between Spitfires and Hurricanes during the BOB was not large. Sure the Spitfire was a much better aircraft but for every two Spitfires produced, they could build three Hurricanes and as I said previously, England's biggest problem during the BOB was shortage of fighters.

A quote from Alex Henshaw who flew more Spitfires than anybody and probably as skilfully as anyone.
"But I have to admit that the later marks, although they were faster than the earlier ones, were also much heavier and so did not handle so well. You did not have such positive control over them. One test of manoeuvrability was to throw her into a flick-roll and see how many times she rolled. With the Mark II or the Mark V one got two-and-a-half flick-rolls but the Mark IX was heavier and you got only one-and-a-half. With the later and still heavier versions, one got even less. The essence of aircraft design is compromise, and an improvement at one end of the performance envelope is rarely achieved without a deterioration somewhere else"



Alex Henshaw missed the "interim" XIV and XVIII and went straight to the 21, which not only was heavier but was fitted with a reprofiled wing. The 21 had a lot of difficulties before its flight characteristics were sorted out and were deemed satisfactory.

#90 Wuzak

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Posted 28 September 2011 - 23:49

Sorry - Mitchell started designing an aircraft in 1933 to use the Merlin engine. If he was designing for the Griffon it would have been a larger aircraft.


And an earlier Griffon, which it would need to be, would not doubt have been physically larger. The Griffon design benefitted very much from the Merlin development and its problems, and was specifically redesigned before it made production so it could be made to fit the Spitfire.

#91 Vanishing Point

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Posted 29 September 2011 - 00:26

Sorry - Mitchell started designing an aircraft in 1933 to use the Merlin engine. If he was designing for the Griffon it would have been a larger aircraft.



Where's the logic in saying that it would have needed to be such a different aircraft when it was proven that a re engineered and developed Spitfire could handle the Griffon's power adequately in service.

Edited by Vanishing Point, 29 September 2011 - 01:15.


#92 Vanishing Point

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Posted 29 September 2011 - 00:45

The difference in kill rates and aircraft lost between Spitfires and Hurricanes during the BOB was not large. Sure the Spitfire was a much better aircraft but for every two Spitfires produced, they could build three Hurricanes and as I said previously, England's biggest problem during the BOB was shortage of fighters.

A quote from Alex Henshaw who flew more Spitfires than anybody and probably as skilfully as anyone.
"But I have to admit that the later marks, although they were faster than the earlier ones, were also much heavier and so did not handle so well. You did not have such positive control over them. One test of manoeuvrability was to throw her into a flick-roll and see how many times she rolled. With the Mark II or the Mark V one got two-and-a-half flick-rolls but the Mark IX was heavier and you got only one-and-a-half. With the later and still heavier versions, one got even less. The essence of aircraft design is compromise, and an improvement at one end of the performance envelope is rarely achieved without a deterioration somewhere else"


The differences in kill ratios between the BoB Spitfires and Hurricanes seemed to reflect very closely the differences in speed and height performance between both types of aircraft.In aircraft development it usually turned out that going for a compromise at the manouvreability end of the spectrum to gain reliable extra speed and performance at greater height to give the advantage of height at the start of a dogfight was better than going for the opposite type of compromise.It's very rarely that any type of progress in aircraft performance during WW2 didn't follow that ideal and probably even recently in air superiority fighters like the F14 Tomcat and F15 v the Mig 29 or SU27 although the Lightning seemed to have been the nearest to ever get the compromise exactly 50/50.

Which is probably why it was the Mk IX that was needed to survive in dogfights with the BMW FW 190 but the Griffon Spits like the Mk XIV were needed to take on the Dora 9.In any of those cases Alex Henshaw wouldn't have wanted to have been flying any of the previous Mk's of Spit or even a Mk IX in the case of the Dora 9.

Let alone a Hurricane :eek: .

But the issue of numbers being better than superiority is something like the logic used on the ground with tanks during WW2.The German gunners said that they ran out of shells before the allies ran out of Shermans.However each of those Shermans contained a crew and in the case of the fall of France during the beginning of WW2 the Luftwaffe didn't run out of planes or ammunition before it had taken out the RAF's Hurricanes first and those casualties in pilots had to be replaced and was one of the reasons why the Battle of Britain and therefore the war was almost lost.

Edited by Vanishing Point, 29 September 2011 - 01:10.


#93 Vanishing Point

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Posted 29 September 2011 - 00:55

And an earlier Griffon, which it would need to be, would not doubt have been physically larger. The Griffon design benefitted very much from the Merlin development and its problems, and was specifically redesigned before it made production so it could be made to fit the Spitfire.


But there's no reasons why logical engineering solutions wouldn't have followed exactly those that actually proved to take place in any event.Just sooner if the Ministry remit and specs had been a lot more demanding,in relation to the performance required,in the fighter specifications that it put out for order,before the war started,at the time of the design stages of the Spitfire and Hurricane.Bearing in mind Supermarine's and Rolls' already proven experience in producing aircraft and engines with the required performance for the job.

Edited by Vanishing Point, 29 September 2011 - 00:57.


#94 Wuzak

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Posted 29 September 2011 - 01:32

But there's no reasons why logical engineering solutions wouldn't have followed exactly those that actually proved to take place in any event.Just sooner if the Ministry remit and specs had been a lot more demanding,in relation to the performance required,in the fighter specifications that it put out for order,before the war started,at the time of the design stages of the Spitfire and Hurricane.Bearing in mind Supermarine's and Rolls' already proven experience in producing aircraft and engines with the required performance for the job.


Mitchell's first Spitfire, the Supermarine Type 224, did not meet performance requirements and the contract went to a biplane....

#95 Wuzak

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Posted 29 September 2011 - 01:33

But there's no reasons why logical engineering solutions wouldn't have followed exactly those that actually proved to take place in any event.Just sooner if the Ministry remit and specs had been a lot more demanding,in relation to the performance required,in the fighter specifications that it put out for order,before the war started,at the time of the design stages of the Spitfire and Hurricane.Bearing in mind Supermarine's and Rolls' already proven experience in producing aircraft and engines with the required performance for the job.


By that argument the Merlin would have been more compact than it was. And it wouldn't have used external oil lines....

Edited by Wuzak, 29 September 2011 - 01:33.


#96 Vanishing Point

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Posted 29 September 2011 - 01:45

Mitchell's first Spitfire, the Supermarine Type 224, did not meet performance requirements and the contract went to a biplane....


It's lucky that the ministry didn't decide to turn all fighter production over to mostly Biplanes and a few Hurricanes during the battle for France and the BoB if they'd have taken that to it's logical conclusion. :eek:


#97 Vanishing Point

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Posted 29 September 2011 - 01:51

By that argument the Merlin would have been more compact than it was. And it wouldn't have used external oil lines....


No I still think we'd just have had something like the Griffon Spit,hopefully Mk XIV,in time for the battle for France and it probably wouldn't have mattered either in that case wether the force would have been around 33% fewer in number than the Hurricanes that went there and failed to do the job.That's assuming that Hawkers didn't/couldn't manage to at least add some more to that figure by joining Supermarines in just building Spits instead of Hurricanes.


#98 Kelpiecross

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Posted 29 September 2011 - 04:03

No I still think we'd just have had something like the Griffon Spit,hopefully Mk XIV,in time for the battle for France and it probably wouldn't have mattered either in that case wether the force would have been around 33% fewer in number than the Hurricanes that went there and failed to do the job.That's assuming that Hawkers didn't/couldn't manage to at least add some more to that figure by joining Supermarines in just building Spits instead of Hurricanes.


If the RAF had something like a Griffon Spitfire ready for the BoB it is highly likely that Adolf would have been aware of it and would have delayed the start of WW2 until he had something similar.

I really don't think you can speculate on history like you do.

I sometimes think that if America had not become independent of England (and had remained associated in a Commonwealth arrangement like Oz et al.) that probably WW1 and WW2 and maybe even the Civil War would not have happened.

But - who knows? - it may have started a new "timeline" where different (and possibly, far worse) wars occurred. And the same may have happened with Grffon Spits etc. and WW2 - delaying the war may have allowed Adolf to have a atom bomb available.

You have probably seen enough Star Trek to know that it doesn't pay to interfere with timelines.

#99 Wuzak

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Posted 29 September 2011 - 08:41

It's lucky that the ministry didn't decide to turn all fighter production over to mostly Biplanes and a few Hurricanes during the battle for France and the BoB if they'd have taken that to it's logical conclusion. :eek:


The Type 224 preceded the Type 300 Spitfire and the Hurricane and was powered by a Goshawk - a Kestrel modified to use evaporative cooling. The Type 224 was outperformed by the Gloster Gladiator, which was ordered into production.

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#100 24gerrard

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Posted 29 September 2011 - 12:38

Hurricanes shot down more enemy aircraft than Spitfires did during the BOB.
Nough said.
The best WW2 aero engines were the Bristol sleeve valve engines.
The Vickers Wellington was the best bomber (Sir Barnes Wallis, also designed the Lancaster), fitted with Bristol sleeve valve engines, it held the line for YEARS before the Americans came in with their B17s and Liberators.
Both these aircraft carried only a small bomb load, smaller than the twin engined Wellington x.
The American poppet valved radials were unreliable and underpowered and four were needed compared to two British Bristols.
The only reason that bomber Command and the Wellington are not celebrated to the same level or higher than the Spitfire and Fighter Command during the same period, is because of bomber Harris and his carpet bombing campaign, that left the American 8th mostly blowing costly holes in the European country side. To get within a half mile of target was a miracle.
The Lancaster (after the Stirling-Bristols and Halifax) were true heavy bombers not medium bombers like the B17.
Later in the war the Mosquito bomber version carried the same load as a B17. (design superiority)

The B36 of post war SAC with six American radials (and 4 jet engines) suffered at least one radial engine strip or change on every long range mission.
The jets were of course of British origin built under a criminal agreement after the war and one of the things that killed the British Empire.

I love the stated use of American fighters against Japanese Kamakasi's, most of the Kamakasi's were pilots with less than five hours and sometimes flying unarmed trainers. Still its all part of the dream I suppose.
Bomber Command from 1939 to 1943 was bombing Europe on its own with a loss rate as high as four in five crews.
Please dont tell me American engines were best, they were not.