Merlin Rolls Royce and Offspring
Printed From: Unofficial Allis
Category: Allis Chalmers
Forum Name: Construction and other equipment
Forum Description: everything else with orange (or yellow) paint
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=8034
Printed Date: 18 Jul 2025 at 9:45am
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Topic: Merlin Rolls Royce and Offspring
Posted By: orangeman
Subject: Merlin Rolls Royce and Offspring
Date Posted: 13 Feb 2010 at 8:58am
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Does anyone know if there was a six cylinder little brother to the Merlin Rolls Royce used in the P51 Mustang?
If so, I would like to power an Allis Chalmers with one.
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Replies:
Posted By: firebrick43
Date Posted: 13 Feb 2010 at 10:43am
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No, its a 60 degree engine to help keep it narrow, so as far as v12s go its quite rough running, in a v6 format it would be really rough running, and vibration is a bane to aircraft. The closest water cooled V aircraft engine you are going to find isn't really an aircraft engine, its a tank engine. The Ford GAA was designed as a v12 aircraft engine but because of politics or other reasons it never was put in one as far as I know. They redesigned it as a v8 and put it in sherman tanks. Warning, this is still a big bastard, 1100 cubic inches and 1200lbs even though its aluminum and put out a healthy 500~hp. It was an uneven fire engine so its pretty rough as well, basically closer to two four cylinders cast together than an even fire v8. If you want a "merlin" engine there is a company (world products) making big block chevy based high performance v8 named merlin. They are no relation to the aircraft but make healthy horsepower and would fit better in an allis |
Posted By: Dave Everett
Date Posted: 13 Feb 2010 at 2:20pm
| There was a V-8 ofspring called a Meteor that was used to power tanks and Antar tank transporters in the british army........ |
Posted By: orangeman
Date Posted: 13 Feb 2010 at 2:51pm
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Dave and Firebrick: The reason I asked about the Merlin is because I was watching some vids on the P51 Mustang, that engine had a health growl and sure made the enemy stand up and take notice.
A wonderful engine which ultimately help to win WWII.
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Posted By: Rick of HopeIN
Date Posted: 13 Feb 2010 at 3:13pm
| Allison had X24 prototypes in their Indy museum. I think they got right to build the Merlin design as part of the wartime agreements. |
Posted By: Dave Everett
Date Posted: 13 Feb 2010 at 3:33pm
| Yes it was Packard that built the american version of the RR Merlin.......dont know if the X type (2 inverted Merlin type 24s on a common crank) actually make it into production, There was a later version the RR Griffon that was much more powerful. |
Posted By: firebrick43
Date Posted: 13 Feb 2010 at 9:23pm
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Rick the allison was a completely different design, half the part count of a merlin, very very complicated engines did the british build. As Dave said, packard was awarded the license to produce the american merlin. Allison was turbocharged where the merlin was supercharged. do you like the sound of a flat plane v8 such as a ferrari, lamborgini or formula 1 car? Is so you will like the sound of a Ford GAA. Its has a flat plane crank as well. With straight pipes its a raspy roar. |
Posted By: Rick of HopeIN
Date Posted: 13 Feb 2010 at 11:27pm
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OK, I was confused. So did Allison only do the larger planes? Most complex piston engine I have seen was the radial engine cutaway at the Naval Air Museum in Pensacola. The story I heard was that Navy was reluctant to put jets on carriers so they took piston engine technology as far as they could. I think the engine was out of a Douglas they used for close ground support in Vietnam. |
Posted By: firebrick43
Date Posted: 14 Feb 2010 at 11:23pm
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Allisons were put into the preproduction p51s. They were however plauged with turbocharger problems at high altitudes and therefore the merlin was chosen to be put into the mustang. The allison was also put into the p38's which where plagued with the same problems in the european theater but performed very well in the pacific due to hotter temps, japs flew at lower altitude, and the pacific theater gasoline was much higher quality. It was also in P39 and P40s The engine you saw was probably out of a skyraider, awesome planes. The engine in that plane was a 3350, and although looks quite complicated to the eye, is very crude in a lot of ways. Compare it to a napier sabre and you will see what I mean. Because of its crudeness, many skyraiders made it back to ship with whole cylinders blown off and other damage that would have stopped the v12 liquid cooled engines in a matter of seconds. Alot is lauded about the p51 but it was not the engine that made it, it was its aerodynamics. If it was above you and had speed, it had the advantage. Get a p51 down in the dirt and start turning it hard, and it was a lousy performer. The big radials had the power to horse the airframe around in these kind of maneuvers. |
Posted By: Rick of HopeIN
Date Posted: 15 Feb 2010 at 5:39pm
| truly neat stuff. I like the sound of em. |
Posted By: Dave(NEPA)
Date Posted: 15 Feb 2010 at 7:00pm
| The Navy liked the radial engine/ propeller combination for the carriers because they had better acceleration at low speeds, could take off from the old carriers a lot easier, and were much more reliable than the old jets. Korea changed their minds as Corsairs weren't very good against MiGs and they finally had to change with the times. Angled decks really helped a lot as a jet could bolter and go around a lot easier without running into a bunch of parked airplanes. My first Division Chief was a plane captain on skyraiders in Vietnam, I wish I could have been a recip mech but they got rid of ADRs a few years before I enlisted. |
Posted By: BobsAc
Date Posted: 14 Oct 2010 at 7:17pm
| OK guys, my Father worked on both the Allison and the RR Merlin during the war...The P-51A/A-36 used the Allison with the single speed super charger.The P-51b razorback was the first with the RR merlin which had a 2 speed super charger which gave that magnificent wing the altitude peformance it craved. The only Allison with turbo-charger was the P-38/F5 Photo aircraft. It in fact performed well in Europe and Africa, as did the lowly P-40. The allison was an excellent engine which has suffered many "slings and arrows" due to the Army Air Corps specs regarding super charging and their lack of forsight in regards to high altitude fighter performance. The Allison performed magnificently in the P-38 due to the turbo super-chargers which trumped that very lack of vision. Don't forget that the US's top two aces flew P-38's, ( in the Pacic theater they also did not get credit for ground straffing kills)... Bob S (US Naval Aviator- retired Engineer-retired). |
Posted By: Coke-in-MN
Date Posted: 14 Oct 2010 at 7:29pm
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I was on the USS Constellation CVA 64 from 1964 to 64 / got out just before Viet Nam. We had a squadrons of AD6 aboard and for close ground support there was no jet that could match them. We did cat them from deck until one lost engine on launch, after that they just taxied into flight. could carry close to it's own weight in armement. Fueled a lot of them using 115/145 Av-Gas, and loaded mapalm on many of them, along withbomb crew loading anti-personel bombs. Big thing with radial was the gallons of oil used along with the gas in short flights. Loved the sound of them and at night the sight of them on takeoff and landing , with the blue flames from exhaust.
When I got off theywere still flying them but the mixture of other planes changed, Demons were replaced with Phantoms, A4D (scooters) became 2 squadrons, F8U Crusaders also went down to 1 squadron plus 4 photo planes. Wilie Fuds also sounded neat biggest plane was Douglas A-3 Skywarrior twin engine bomber.
 ------------- Faith isn't a jump in the dark. It is a walk in the light. Faith is not guessing; it is knowing something. "Challenges are what make life interesting; overcoming them is what makes life meaningful." |
Posted By: Coke-in-MN
Date Posted: 14 Oct 2010 at 7:58pm
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PACKARD V-12 MARINE ENGINE
The Packard 4M-2500 engine was utilized in all U.S. Navy World War II PT boats. This engine was based on the 1925 Liberty aircraft engine which was earlier converted for marine use in racing boats. During the war the Packard engine went through various performance updates and modifications. With early engines rated at 1100 h.p. and progressing to 1500 h.p. during the war. The Packard 4M-2500 engine was a supercharged, water cooled, gasoline powered V-12 engine, weighing approximately 2900 pounds. The Packard 4M-2500 marine engine was not the Rolls-Royce Merlin, nor did U.S. Navy PT boats use the R.R. Merlin engines, which is sometimes misstated. However, Packard did built a version of Merlin Engine under contract by Britain for British aircraft use.
------------- Faith isn't a jump in the dark. It is a walk in the light. Faith is not guessing; it is knowing something. "Challenges are what make life interesting; overcoming them is what makes life meaningful." |
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Posted By: DMiller
Date Posted: 14 Oct 2010 at 8:04pm
| A lot of old La France fire trucks from the fifties had the Lycoming Patent V-12 60 degree gas engines, real pigs to work on. Not aircraft grade, heavy cast blocks, a lot of iron and steel for heavy truck use. |
Posted By: Rick of HopeIN
Date Posted: 14 Oct 2010 at 8:04pm
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A mechanic I worked with, now retired did 'pilot recovery' from PT boats at Japan bases after the war. He always thought the big gasoline motors were Allisons. Maybe not?
------------- 1951 B, 1937 WC, 1957 D14, -- Thanks and God Bless |
Posted By: Coke-in-MN
Date Posted: 14 Oct 2010 at 8:14pm
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Waterous Co in St Paul MN (fire plug mfg. and fire pumps) used the Packard engines on their test bench for pumps. After the war they bought several on surplus sale and kept them in storage just for future use. Friend worked ther and sait they never did use all the HP to test pump as no pmp they made could stand the HP for long at full revs. ------------- Faith isn't a jump in the dark. It is a walk in the light. Faith is not guessing; it is knowing something. "Challenges are what make life interesting; overcoming them is what makes life meaningful." |