> That's survivor bias and sheer production numbers of us bombers
To an extent yes, but the US certainly produced liquid cooled aircraft engines as well, like the Allison's and Packard Merlins powering many famous WWII aircraft. If they would have considered liquid cooled engines obviously superior, I'm sure they would have preferred those in post-WWII piston aircraft.
> neither the german nor the UK ones did (mostly, exceptions always exist).
The UK produced nearly 60000 Bristol Hercules radials, practically all used in multi engined aircraft (Beaufighter, Wellington, Stirling, Halifax being the major ones AFAIK). Sure, a much lower production numbers than the famous Merlin at 150000 engines, but far from insignificant.
Similarly, Germany produced over 60000 BMW 801 radials, mostly used in the FW190A fighters but some were also used in some Ju88 variants. In comparison the DB 600 engines powering mostly Bf 109 was about 60000 as well, and about 70000 Jumo 21X series used mostly in bombers.
So very broadly speaking, of total aircraft engine production, both UK and Germany produced about 1/3 radials and 2/3 liquid cooled.
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.
The 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.
Allison 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)
The 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.
Ah, 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)
To an extent yes, but the US certainly produced liquid cooled aircraft engines as well, like the Allison's and Packard Merlins powering many famous WWII aircraft. If they would have considered liquid cooled engines obviously superior, I'm sure they would have preferred those in post-WWII piston aircraft.
> neither the german nor the UK ones did (mostly, exceptions always exist).
The UK produced nearly 60000 Bristol Hercules radials, practically all used in multi engined aircraft (Beaufighter, Wellington, Stirling, Halifax being the major ones AFAIK). Sure, a much lower production numbers than the famous Merlin at 150000 engines, but far from insignificant.
Similarly, Germany produced over 60000 BMW 801 radials, mostly used in the FW190A fighters but some were also used in some Ju88 variants. In comparison the DB 600 engines powering mostly Bf 109 was about 60000 as well, and about 70000 Jumo 21X series used mostly in bombers.
So very broadly speaking, of total aircraft engine production, both UK and Germany produced about 1/3 radials and 2/3 liquid cooled.