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Allisons and Packard Merlins happened IIRC due to RAF orders and were at least partially related to British Merlin engine. Briston Hercules was fitted to sever
by p_l 4y ago
Allisons and Packard Merlins happened IIRC due to RAF orders and were at least partially related to British Merlin engine.
Briston Hercules was fitted to sever plane types due to lack of production capability for the more complex liquid cooled engines, this was specifically a case with Beaufighter which suffered badly for it.
- jabl 4y agoThe Packard Merlin was a license produced version of the Rolls-Royce Merlin, famous for powering the P-51. The Allison, OTOH, was AFAIK an entirely US design.
- deleted 4y ago[deleted]
- p_l 4y agoAllison was produced for P-51, which was designed to specification done by RAF and designed around Merlin engine. The reasons for existence of Allison engine were iirc part political part practical (second sourcing, low spin up of license production as Packard team learnt Merlins, low amount of British Merlins available)
- jabl 4y agoThe Allison was much older than the P-51 airframe, it was used earlier e.g. for the P-39 and P-40. My memory of Mustang history is a bit hazy, but IIRC the Mustang was originally meant to use the Allison and later they switched to the Merlin to get better high altitude performance as the Allison lacked a two-stage supercharger. But maybe you're right that it was originally meant for the Merlin and the Allison was a stopgap until Merlin production ramped up in the states.
- p_l 4y agoAh, I forgot about P-39 and P-40. Pretty sure Merlin was present in the design from start, or at least consideredin contract if not manufactured from start with it (I somehow doubt the RAF would have accepted the high altitude performance of Allison engine)