Rich, the idea would be to use the intended prop for the task as your "control prop", like the 8x8 example. I think the thrustier applications [like 3d with a 12x3] make this type of study more relevant than what we need for speed. I don't think you will get much unloading while the engine is bolted to the kitchen table. This is why I think the best comparisons are done at the field.