AZDoug

What's all that **** on the back? Supercharger?

i like the Allison V12 design a bit better.

Doug

JohnZ

Yup - two-stage, two-speed supercharger; that's what gave the Merlin 61 and 65 more power at altitude than the Allison, which had a single-stage, single-speed blower. The Merlin and Alllison basic engine designs were almost identical, with the Allison having slightly more displacement than the Merlin (1710 cubic inches vs. 1650).

AZDoug

The last versions of the Allison were rated about 2800 HP. Dunno what the Merlin put out. Not sure if the High HP Allison was fielded during WWII, though.

IIRC, Packard made a Merlin clone under license to RR (upgraded to mass production, uniform parts, rather than hand fitting everything), not sure if those used the two stage superchanrger, though.

Doug

BLee

Pretty impressive for something that was originally designed in 1929.

Here's some Wiki info http://en.wikipedia.org/wiki/Allison_V-1710

They also made a V-3420 which mated 2 V-1710 engines at an angle. I don't know if it was ever installed or even got out of the testing phase.

I worked on a P-39 in Central Texas during a previous profession as an avionics guy. I always thought they had a smaller Allison engine but they also had a V-1710 in a different configuration. The F-82 twin engined fighter also used V-1710s with different supercharger setups.

JohnZ

Yes, they did; other than the first prototype Mustangs converted for evaluation in England from the Allison to the Merlin 61, all the Merlins used in Mustang production were built by Packard under license and had the two-stage/two-speed supercharger.

mscaggs

64_365

I understand Packard actually did a better job of making these engines than Rolls. Love those WWII aircraft engines!