When I flew the Merlin we were told in ground school the prop turned
half engine rpm. Probably because that termonology easier to remember
than 0.42 ratio.

Power was adjusted using engine rpm (and MP) so prop speed never
entered into the equation during flight.

Big John
************************************************** ****************************

On Fri, 28 Nov 2008 00:05:28 +0100, GTH
wrote:

Morgans a écrit :

Many of the old big "V" and inline engines were 2:1, and were using the
front end of a very strong camshaft as the prop drive, weren't they?

Rolls Royce and Allison V engines were (are) overhead camshafts.
The prop reduction gear was driven from the nose of the crankshaft.
According to Rolls Royce, the Merlin XX drive ratio was 0.42.

Best regards,