If you ever do the airspeed thing, let us know what the results are. I remember when we bought our first rotary, an R40. We set the fan choke according to the book for oats - we had the separator running with the engine idle for whatever reason - I stuck my head in the back of it and the wind nearly took my breath away. I remember thinking that there was no way that oats were going to stay in the back of that thing but those accelerator rolls do their jobs. I can only imagine what the airspeed would be with choke wide open and sep. running at full speed!