RE: Master Airscrew props
The older, up to 11" diameter MA props, gave this company a very ineffective reputation...
The typical situation was; this prop 'buzzing along' at high RPM and the model hardly dragging itself forward, with the sky seeming to be all up-hill...
Changing to a new prop (MA Series II) of the same size (11x6) made a lot of difference... Changing to a Bolly 11.5x5 made even more difference.
That old MA prop was pretty good for stirring paint...