.....I got a little surprise today, I did some Master Airscrew testing on a run of the mill
Magnum .40 in the Twin Star of mine. I hadn't run the engines for about a year and a half
and the fuel is opened 2004 vintage, but what the hay....

10-6....13,500
10-7....12,700
10-8....11,850

(get this)

10-9....11,100

Yes, Boys and Girls....you can use a 10-8 MAS prop on a .40 size engine.

FBD.