Clay_Allison
Staff Sergeant
- 1,154
- Dec 24, 2008
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The R-1830 had a two-stage supercharger before the Merlin did IIRC. If it had been given more funding, it might have been an R-2000 with good high-alt performance by Jan 1 1942.The Allison lacks the main advantage of an inline: the option of a moteur-cannon. So the Twin wasp wins the match.
Two different engines, two different functions - actually it would be the war department telling you what engine to put into your aircraft based on your design.
The Allison lacks the main advantage of an inline: the option of a moteur-cannon. So the Twin wasp wins the match.
If the P-40 were never developed as an Allison engined plane and was instead a better P-36 with armor, self sealing tanks, realistic armament and two-stage supercharging, how would that have affected early AAF operations?
Similar, what if the P-51 was built to fly with Packard Merlins from day one?
Did I say no more Wright R-1820s? Anyway, I also said fighter production and meant it. Someone needed the money to build a two stage supercharger, denying one and feeding the other might be the ticket.Choosing between the P&W and the Allison gives Wright a rather unfair advantage doesn't it?
Allison powered B-24s?
Allison powerd C-47s
Allison powered Catalina's
OK, I know you said fighter engine but there was no way that the P&W R-1830 wasn't going to stay in contention in that catagory, With the basic engine in production for so many other aircraft there was no chance of it being dropped.
That being said the Allison had more potential. Liquid cooled V-12 engines were heavier for their displacement but could achive more HP per cubic inch. The question starts to become which engine could give the most HP per pound and/or per sq ft of frontal area. the close cowled BMW style of installation still being a few years off.
In 1938 the choice is between the R-1830 which was a proven engine that was in production but perhaps lacking in development potential and the V-1710 with more potential but was, despite passing a type test, a tool room produced experamental engine.
Maybe P&W did need more money and engineering staff but they were one of the 2 largest engine makers in the US at the time. Production engines were the Wasp Jr., the Wasp, the Hornet, the Twin Wasp Junior, and the Twin Wasp. For a brief period of time they tried to market the Twin Hornet and were working behind the scenes on the R-2000, the R-2800 and several liquid cooled projects. And they still had trouble with the 2 stage supercharger on the R-1830. An extra 10% of displacement probably wouldn't have turned things around much going for the R-2000. Plwase remember that 14 R-2800 sized cylinders work out to 2180 cu in and also that the later high powered R-2800s had little more in commen with the 2000hp versions than the bore and stroke. Forged heads instead of cast, cylinder barrels with Aluminum fin muffs on them instead of machined steel fins, different crankcases, crankshafts, pistons and so on. Without a total redsign of the R-1830 (and different manufacturing techniques) the R-1830 was not going to reach the output of the later R-2800s per cubic inch.
I'm talking about a plane at least as much a new plane as the P-40 was with a radial engine instead of an inline. I'm not talking about bolting new models of R-1830 onto the old P-36 airframe. I would want one capable of getting the R-2000 when available.Haven't we been over this before?
While you can cetainly put a P-40E style wing on a P-36 style fuselage and put in armour and self sealing tanks, the two stage supercharged R-1830 might have been just a bit harder. The weight might not have been a big problem but the volume needed by the intercooler might have been just little more difficult.
THe demonstrated performance of the R-1830 engine, while better than the Allison engines, wasn't so dramaticly better that the draggier radial engine vesion would have turned into a super fighter. the Two stage engine offered 1000hp at 19,000ft at "military rating". If somebody has any better information please let me know.
The P&W sytem of two stage superchargering was different than the Merlins. The P&W system used an engine driven supercharger with one gear ratio. the auxilary stage was not driven at sea level or for takeoff so the engine operated as a single stage engine until the hight of about 8-9,000 ft was reached at which point the auxilary supercharger was clutched in. This boosted the poer but as the plane climbd the power fell off untill the plane reached aboiut 16,000-17,000 at which point the auxilary supercharger shifted to high gear and power peaked at 19,000ft. The intercooler was between the auxialry stage and the engine supercharger and so did nothing to cool the intake charge after it left the engine supercharger, The intercooler was an air to air unit but I have no idea how good it was.
Note that as far as I can tell this is just about the same system used on the R-2800s in the F4U, the Hellcat and the P-61 A B models.
If the P-51 had flown as a Merlin powered plane from the start it would have first shown up in the Summer of 1942 ( using the 2 speed but not 2 stage engines from the P-40F) which would mean well over 600 Allison engined versions not being produced and probably a several month delay in getting the production ramped up for the Merlin version. P-51B is still going to have to wait for the 2 stage Merlin to be developed and put into mass production.
It might have ment no Mustang at all. With no Merlins ( of any supercharger type ) available from US sources in 1940 the British might never have signed the contract to develop the Mustang.
Tomo - the P-39 used the Allison and had both 20mm and 37mm cannon..ditto the P-63.. firing through hub.
True, yet it was the airframe that enabled the cannon mounting, not the engine. An exception of the rule, I'd say.
The later model Allisons with supercharger (like -117) were very powerful and developed ~ 1800 Hp and culminated in the P-82 equipped 1710-143 with supercharger and WI for 2200hp.
Did I say no more Wright R-1820s? Anyway, I also said fighter production and meant it. Someone needed the money to build a two stage supercharger, denying one and feeding the other might be the ticket.
I'm talking about a plane at least as much a new plane as the P-40 was with a radial engine instead of an inline. I'm not talking about bolting new models of R-1830 onto the old P-36 airframe. I would want one capable of getting the R-2000 when available.
First the R1830 has more frontal area = more drag
Allison should have gone on their own dime and continue both the turbosuper-charger and multi-stage superchargers the P-39 was estimated to be capable of 375mph at 20000 ft with the turbo (fully armed and armored)