Hi all this has been an interesting thread and has got me thinking. I am going to build a new test bench to run a multitude of tests running a spare YS91fz with a variety of props in the same size range. The fuel will all be the same batch, and I will test for rpm, thrust and also air speed behind the prop, which will be in a nacelle type set up with a windspeed indicator. This could be quite interesting me thinks[sm=confused.gif] I dont know if it will actually prove anything specific as such but will at least give me something to do