What was the problem with the allison engine?

[Shortround6]

No, with respect, the Merlin was the most successful aero-engine,its not all about being English either.
It powered most of the significant WW2 aircraft and secured our liberty.
I have the utmost respect for the P51 but, the Americans could not produce an engine of sufficient performance in time for when the P51 was needed most.
Cheers
John

With respect, that is certainly debatable. It also a bit about timing.
The P&W R-1830 was produced in more numbers than any other larger aircraft engine and might lay claim to most successful on that basis. It did power a number of significant WW II aircraft and certainly played a large part. It was, however a bit earlier in timing than the Merlin and not capable of the power needed for first rate combat aircraft after 1941-42 except in turbocharged 4 engine installations (B-24).

The R-2800 was a bit later in timing than the Merlin and certainly powered a fair number of "significant WW2 aircraft" unless you think the B-26, Lockheed Ventura, A-26, P-47, F-6F, F4U, were insignificant, this not counting minor types and end of war and post war types. With over 125,000 P&W R-2800s produced it may be below the Merlin in numbers but it did go on to be produced for a number of years after merlin production stopped, but that is only natural considering it's later timing.
Granted neither P&W engine saved England in the BoB or was there for the early part of the European air war (although the R-1830 did it's bit in the battle of the Atlantic and helped with the Bismark).

 

[renrich]

Glider, there is online a source for a complete report of that 1944 Fighter Conference. The reviews say that it is an excellent book for us WW2 airplane wingnuts. I have ordered it and when received I will try to transmit any relevant info to this forum. In fact you can count on me using that report just as I do Dean's book to back up all my arguments My personal choice of an engine if I was going flying and especially into combat as far as confidence that the engine would get me there and back would have been the R2800. The war would have been tougher to win without either the Merlin or the R2800.

 

[Readie]

I seem to recall a couple of engines from Pratt Whitney. Think they were the R-1830 and R-2800.

WW2 started in 1939 and British liberty was at its greatest peril in the early years of the war. There is an earlier post about the 1930's need to develop more advanced aircraft in Europe. A lot of development this passed America by as you were simply not involved.

When America joined in WW2 you brought a variety of engines, some good as you name and others not so er,... well developed like the Allison.
That is not to say that the Allison was a bad engine. it wasn't but, for a variety of reasons it did not have the power of the Merlin.
Why else would the P51 have been fitted with them?

The Merlin was one of those designs that had fortuitousness to be available to power our aircraft when we needed them most.
There is only one Merlin and loads of US radials that were as good as each as other and go equally un-remarked on by history.

Cheers
John

 

[Readie]

With respect, that is certainly debatable. It also a bit about timing.
The P&W R-1830 was produced in more numbers than any other larger aircraft engine and might lay claim to most successful on that basis. It did power a number of significant WW II aircraft and certainly played a large part. It was, however a bit earlier in timing than the Merlin and not capable of the power needed for first rate combat aircraft after 1941-42 except in turbocharged 4 engine installations (B-24).

The R-2800 was a bit later in timing than the Merlin and certainly powered a fair number of "significant WW2 aircraft" unless you think the B-26, Lockheed Ventura, A-26, P-47, F-6F, F4U, were insignificant, this not counting minor types and end of war and post war types. With over 125,000 P&W R-2800s produced it may be below the Merlin in numbers but it did go on to be produced for a number of years after merlin production stopped, but that is only natural considering it's later timing.
Granted neither P&W engine saved England in the BoB or was there for the early part of the European air war (although the R-1830 did it's bit in the battle of the Atlantic and helped with the Bismark).

Shortround, of course its debatable, I express my views as you do.
No one would argue that the R2800 wasn't a splendid aero engine and,as you say, powered a lot of aircraft.
My point about the Merlin is acknowledged by your 'timing' comments. America joined both WW's later and, after a lull, produced the goods that helped win both wars.
The Merlin was sensibly used in preference to the Allison so that 'we' had the P51 that was so desperately needed.
Why not use the best that is available? To my mind that sums up the P51.
The Merlin was used in tanks, bombers, fighters and air-sea rescue craft. A fantastically versatile engine with all the best heritage of British engineering.
Cheers
John

 

[Lighthunmust]

Glider, there is online a source for a complete report of that 1944 Fighter Conference. The reviews say that it is an excellent book for us WW2 airplane wingnuts. I have ordered it and when received I will try to transmit any relevant info to this forum. In fact you can count on me using that report just as I do Dean's book to back up all my arguments My personal choice of an engine if I was going flying and especially into combat as far as confidence that the engine would get me there and back would have been the R2800. The war would have been tougher to win without either the Merlin or the R2800.

I have the book and it is a must have. Only two complaints. There are too many apples and oranges comparisons with regard to comparably developed versions of the aircraft tested. The book leaves you craving more information. If only the parties involved at the Conference had the aircraft resources available, time available to create more extensive test criteria, and the foresight to know how much all of us Warbird Nuts would wish we had better documentation. I'm sure any thoughts of posterity never crossed their minds of the members of the Conference.

P.S. I agree. If my hide were on the line, I'd want the sound of round in front of me.

 

[MIflyer]

The Merlin was built by Packard under license – and that includes the V-1650-1's (Merlin 45) which were only single stage supercharged as well as versions fitted to Canadian built Mosquitoes and Lancasters, and the Merlin 60 for the P-51.

I understand that Packard redesigned the Merlin 60 supercharger gear set (as well as successfully fitting the engine with removable heads, which RR had tried and given up on due to coolant leaks). And Packard had Wright redesign the supercharger impeller for the V-1650. I would expect that all of this was done for produceability rather than for performance.

Interestingly enough, one pilot's manual I have for the P-51 says that the best endurance and presumably lowest fuel consumption is at altitudes above 25,000 ft with the supercharger switch set in the manual "low speed" position. Standard US practice for longest range with the V-1710 and R-2800 in WWII was the exact opposite – low altitude and high boost, which I find a curious difference in technique.

I recall that the royalties on the Merlin paid by the US was $1,500 per engine, which sounds trivial now.

But also realize that the first Secretary of the Air Force, Stuart Symington, was the former head of GM. When the V-1710 did not work out in the F-82 and NAA had to store the completed airframes at their Downey facility (a former Consolidated Vultee plant) for a few years, NAA did some experiments with the engine to try to fix it. Reportedly, Allison then complained to their management, who called the SECAF, and NAA was told to quit fooling around with the V-1710 because Allison knew more than they did. Of course, by that time Allison was focused on jets and had little interest in fixing the V-1710.

I still contend that the problem with the V-1710 in the F-82 was the lack of liquid Inter/Aftercooler. They tried to offset that with water injection to cool the fuel/air charge going into the engine but that was not good enough. NAA thought the engine needed antibackfire screens, fitted one with them, and said that it helped.

I read that the USAF studied the possibility of fitting P-51's with R-2800's after WWII in order to avoid paying the Merlin royalty. An excellent engine and an excellent airframe, but I think it is good that they never built that monstrosity.

By the way, the RCAF said they hated the Spitfire Mk. XXVI, the version fitted with the bubble canopy, clipped wing tips, and Packard V-1650's. The engines were too unreliable for the low altitude mission they had.

In case you have not read the Gingrich/Forsecten novel "1945" they decide to take the Merlins off the P-51's and fit them on the grounded F-82's to have airplanes capable of dealing with German jets.

 

[fastmongrel]

I understand that Packard redesigned the Merlin 60 supercharger gear set (as well as successfully fitting the engine with removable heads, which RR had tried and given up on due to coolant leaks). And Packard had Wright redesign the supercharger impeller for the V-1650. I would expect that all of this was done for produceability rather than for performance.

Merlins had one piece blocks and heads at first but later models had seperate heads. Packard didnt do any major redesigning they were licensed to build the engines not develop them. Packard did make changes but for production and supply reasons, the Bendix carb and the Wright supercharger drive coupling which was a better design than the RR one. British production also later used the Wright supercharger drive. The biggest change Packard made was using Pontiac silver lead main bearings which were longer lasting than the original copper lead ones.

 

[Hop]

Packard didn't have to pay any royalties during war time. Rolls Royce wanted royalties post war, but I believe Packard stopped production before any were paid.

I understand that Packard redesigned the Merlin 60 supercharger gear set (as well as successfully fitting the engine with removable heads, which RR had tried and given up on due to coolant leaks). And Packard had Wright redesign the supercharger impeller for the V-1650. I would expect that all of this was done for produceability rather than for performance.

Most of the changes in design were carried out by Rolls Royce and intended for the new 60 series engines. Packard started production before Rolls Royce began production of the 60 series, so got the improvements first. I don't know specifically about the supercharger impeller, but that's certainly true about the 2 piece cylinder head, something Rolls Royce had been preparing since before the war started.

 

[davparlr]

Can I ask the background of the pilots? I mention this as I would expect a USN pilot to go for the R2800 and any USAAF that flew aircraft powered by the R2800, and any P51 pilot or RAF pilot to go for the Merlin.

People understandably have faith in what they have experienced and trusted.

There were were quite a few representatives in the program including RAF and subcontractor pilots. I found a list of representatives, but no pilot breakdown. These representatives include RAF, RN, and DeHavilland. There were no representatives from Supermarine or RR, although Packard was there. Typically, pilots did not rate the aircraft they were associated with. For example the Navy rated AF aircraft and vice versa. I do not know how many of the representatives were pilots but 36 rated the P-51D. However, since AF were not necessarily rating the P-51, many more pilots may have been present.

 

[Glider]

Glider, there is online a source for a complete report of that 1944 Fighter Conference. The reviews say that it is an excellent book for us WW2 airplane wingnuts. I have ordered it and when received I will try to transmit any relevant info to this forum. In fact you can count on me using that report just as I do Dean's book to back up all my arguments My personal choice of an engine if I was going flying and especially into combat as far as confidence that the engine would get me there and back would have been the R2800. The war would have been tougher to win without either the Merlin or the R2800.

With comments like that I have just ordered the book. Now how do I get it in past the wife?

An observation re the Rolls Royce vs Packard Merlin. I had a book on the BOB flight and the Lancaster had at one time three RR engines and a Packard. You could always tell the Packard as it ran at a higher temperature than the RR engines. Still within limits and no problems but just a little higher, which was often commented on by new or visiting pilots who were worried that there might be a problem.

 

[Lighthunmust]

I read that the USAF studied the possibility of fitting P-51's with R-2800's after WWII in order to avoid paying the Merlin royalty. An excellent engine and an excellent airframe, but I think it is good that they never built that monstrosity.

In February 2000 I wrote a letter to the editors of Flight Journal concerning their special edition "WWII Fighters". I was writing to disagree with Eric Brown's article "Serial Killers" (yes I know I have some nerve to disagree with a living legend). The disagreement was with the methodology he used for determining that the best fighters of WWII were Spitfire MkXIV, FW-190D, and Mustang MkIV aka P-51D in that order (yes I know I am a pipsqueak who he would consider too insignificant to even acknowledge). I specifically mentioned that the USAF considered use of the R-2800 in Mustangs (this is the part where I am sure I lost them if I ever had them taking me seriously). Flight Journal never wrote me back, however three years later they published an article by Corky Meyer where he picked the R-2800 powered P-47 as the best fighter of WWII. The P-47 was my choice when I wrote the letter in 2000.

I cannot recall where I heard of this study you mention. Do you have any idea where confirmation could be found?

 

[renrich]

I am no aero engineer but I don't see anyway that fitting the R2800 could benefit the P51. The Chrysler V12, hemi aircraft engine would seem a lot better fit.

 

[Lighthunmust]

I am no aero engineer but I don't see anyway that fitting the R2800 could benefit the P51. The Chrysler V12, hemi aircraft engine would seem a lot better fit.

I completely agree. The idea of putting a R-2800 in a Mustang is more an indiction of great respect for the engine than the rationality of the people who ordered the study. If the USAF had more P47s than P-51s in 1950, do you think they would have been deployed to Korea instead of the 51s?

 

[Shortround6]

I am no aero engineer but I don't see anyway that fitting the R2800 could benefit the P51. The Chrysler V12, hemi aircraft engine would seem a lot better fit.

Nope, Not much a fit at all. It was actually a V-16.

For what it is worth see Wiki; Chrysler IV-2220 - Wikipedia, the free encyclopedia

Several feet longer than the Merlin and 700-800lbs heavier (without turbo). Since it was sort of 2 V-8s couped together, Propeller drive came out of the middle of the engine between cylinders 4 and 5 in each bank, shortening it to a V-12 would have been difficult.

 

[MIflyer]

Lighthunmust:

From what I recall it was a letter published in an aviation magazine in the timeframe 1988-1993. I was assigned to the Pentagon then and got a lot of reading done on the Metro going to and from home.

From what I recall the writer said he was on the engineering team that studied putting the R-2800 in the Mustang. No doubt that was spurrd by the Korean War in which the P-51 was one of the few effective ground attack aircraft the USAF had. Not only was the availibility of engines a possible issue but so was the vulnerability of the 51 to ground fire.

I would bet on Air and Space Magazine as the source since at that time it was one of only 2 aviation magazines I subscribed to, the other being the EAA Sport Aviation mag, which would not have been likely to cover that sort of thing.

Ironically the USAF had just about phased out the perfect airplane for the mission in Korea, the P-47N, by that time. Of course one reason the Mustang was so popular was that they had phased out just about every other prop-driven fighter the USAF had in the area in favor of the P-51 and even they were few in number. I have wondered what it would have been like if they could have recovered some of those P-61's sitting around the islands after the war or the 50 P-38's they scrapped shortly before the North Koreans invaded.

 

[Milosh]

WW2 started in 1939 and British liberty was at its greatest peril in the early years of the war. There is an earlier post about the 1930's need to develop more advanced aircraft in Europe. A lot of development this passed America by as you were simply not involved.

When America joined in WW2 you brought a variety of engines, some good as you name and others not so er,... well developed like the Allison.
That is not to say that the Allison was a bad engine. it wasn't but, for a variety of reasons it did not have the power of the Merlin.
Why else would the P51 have been fitted with them?

The Merlin was one of those designs that had fortuitousness to be available to power our aircraft when we needed them most.
There is only one Merlin and loads of US radials that were as good as each as other and go equally un-remarked on by history.

Cheers
John

And the Allison could have powered those Spitfires and Hurricanes in GB's hour of peril as it put out similar HP as the single stage Merlins of the day. When fitted with the GE turbocharger, the Allison put out more HP at altitude that the 2 stage/2 speed Merlins.

 

[Lighthunmust]

Lighthunmust:

From what I recall it was a letter published in an aviation magazine in the timeframe 1988-1993. I was assigned to the Pentagon then and got a lot of reading done on the Metro going to and from home.

From what I recall the writer said he was on the engineering team that studied putting the R-2800 in the Mustang. No doubt that was spurrd by the Korean War in which the P-51 was one of the few effective ground attack aircraft the USAF had. Not only was the availibility of engines a possible issue but so was the vulnerability of the 51 to ground fire.

I would bet on Air and Space Magazine as the source since at that time it was one of only 2 aviation magazines I subscribed to, the other being the EAA Sport Aviation mag, which would not have been likely to cover that sort of thing.

Ironically the USAF had just about phased out the perfect airplane for the mission in Korea, the P-47N, by that time. Of course one reason the Mustang was so popular was that they had phased out just about every other prop-driven fighter the USAF had in the area in favor of the P-51 and even they were few in number. I have wondered what it would have been like if they could have recovered some of those P-61's sitting around the islands after the war or the 50 P-38's they scrapped shortly before the North Koreans invaded.

I also subscribed to Air&Space during that time frame. When I finished my assignment at the Puzzle Palace at FGGM, just northeast of the Five-sided Asylum, many of my possessions were "lost" by the moving company. I'll bet your right, it was in a back issue of my "lost" Air&Space collection.

Considering the strong desire of the USAAF and USAF to get rid of all those left over WW2 aircraft, for many reasons including not giving Congress the opportunity to deny funding for shiny new jets, it is amazing they had the Mustangs. Just imagine the difference in combat effectiveness, and lives saved on the ground and in the cockpit, if they had sufficient quantities of P-47s and P-61s. Talk about bad timing for scrapping the P-38s. I was not aware of that incident.

 

[Piper106]

After having read Dan Whitney's excellent "Vees for Victory", I decided that both side of this arguement are right... and both sides are wrong. Allison engines were every bit as powerful at allitude the comparable Merlin engines, but...

What has condemed the Allison is that fact that it took their engineering department about two extra years to get their engines to the same level of development. It took Allison until nearly 1943 to get their 9.6:1 ratio high allitude single stage single speed blower into the field, while the comparable Merlin 45 was just a little too late for the Battle of Britian. The two stage mechanical Allisons had the same power at allitude as the Merlin 60 serieds engines but the Spitfire 9 with the Merlin 60 was being issued to the filed in late 1941, while the P-63 with two stage Allison was just starting into production in late 1943. The Allison G6 engines for the P-82 again were comparable in power at allitude to Merlin 100 series engines but again, Allison was about 2 years behind (1947 vs.1945).

And in battle two years is forever.

That is all I think I know.

Piper106

 

[wuzak]

And the Allison could have powered those Spitfires and Hurricanes in GB's hour of peril as it put out similar HP as the single stage Merlins of the day.

Not sure that Allison was ready to produce sufficient quantities of the V-1710 to power Spitfires and Hurricanes before 1940.

 

[wuzak]

Packard didn't have to pay any royalties during war time. Rolls Royce wanted royalties post war, but I believe Packard stopped production before any were paid.



Most of the changes in design were carried out by Rolls Royce and intended for the new 60 series engines. Packard started production before Rolls Royce began production of the 60 series, so got the improvements first. I don't know specifically about the supercharger impeller, but that's certainly true about the 2 piece cylinder head, something Rolls Royce had been preparing since before the war started.

This is my understanding. The design and testing work for the separate heads, which was to solve the leaking problem, had been completed, but the decision was to delay the introduction to coincide with the introduction of the 60 series engines. The reasoning being that there would be too much disruption to production (once to introduce the separate heads, and another to introduce the two stage Merlin). Packard changed over two two stage engine production earlier than RR, and introduced the separate heads first. Not sure if Packard introduced the separate heads on the single stage engines, though. I have a suspicion that all Packard's Merlins had separate heads.