Charles Talleyrand wrote:

"Eunometic" wrote in message om...
My feeling is that knowledge of materials for engine development was
what kept engine weight up and kept down the performance of most of
these aircraft. For instance an engine of the quality of the cyclone
seen on Charles Lindbergs Spirit of St Louise would have immeasurably
improved the performance of these aircraft especially if fitted with
NACA style cowlings. It most certainly was easily buidable by the
fabrication techniwques of the day. Prior to that engines were bulky
liquid cooled models or clumsy rotaries.

Suppose someone gives them a construction manual and a prototype
of a radial engine (probably without the turbocharger) for any common
radial engine of the 1940s. Can they get the correct alloys and build to
the needed tolerances?

No, and just as importantly, they probably couldn't produce fuel of sufficiently high octane to allow it to
produce the higher power it's capable of, even if they could build the engine, and chances are the oil would be
inadequate as well (petroleum engineers with a history minor should now weigh in). If you want to postulate time
travel for a one-time deal, fine, but if you're looking for something that could actually be produced 20 years
earlier and be supported for the long term, it just ain't gonna happen.

Guy