What's a good prop for an OS 40FP with a Davis Diesel head on it?

Ted

Ted,


A 12x6 would be a good choice. Perhaps even a 12x7 / 13x5 would make even better use of the available torque.

I had a 12 x 6 on my ST-46.
It ran real good.

I ran a 12.5x6 Bolly Clubman on my MVVS .49.

It spun it at 10,300 - 10,400 RPM, which most would consider a bit high for a 'Diesel convert' (i.e. too small to make full use of the tremendous torque of the Diesel).


So, I recommended only a slightly smaller size as the minimum for the meager .40FP...

This AJC (Andrew Coholic) head MVVS is now in the trusty hands of Dave Hobbs (Hobbsy).

Dar brought up the increased torque of diesel conversions rule of the thumb, approx when converting to diesel a 40 puts out almost the torque of a 50-60 depending of course on the engine you can go up a inch in diameter or pitch over glow or more depending on rpm desired all my 40 conversions MVVS, Irvine, ST turn a 12x6 in the 9500 to 10000 range thus yes a 13x5
11x7 ,13x5 work fine my graupner 12x6 does 10000 on the irvine the wood zingers 9500 ,a 12x7 still should be around 9000.Also intresting they turn almost the same rpm on the 52 4 strk glow on the same props I use a variety of 12x6s on 4 strk 52s and the 40 2strks glow diesel converts 12x6s these are on sport and trainer type planes,the pulse 40 when completed will be tried with a 13x5 or 13x4 to see how it does< If I use the OS46AX conversion might go the 13x5, the ST and Irvine, MVVS 40 have NEVER failed to preform well with 12 x6 regardless of brand
martin, Davis is very pro OS conversions since they are consistantly issue free ditto with irvines martin

of course the made in USA engine Fox and K and B in same class quality wise

Thanks for the info. I've got an APC 12/6 I'llstick it on and try it.