enginehistory.org

rwahlgren · Joined: 15 Aug 2003 Posts: 324

http://www.enginehistory.org/runners.htm

I would like to know what keeps some of these from taking off?
I really liked the Tulsa 3350 prop almost hitting the ground, it looks like its pulling the stand over a little bit. I would like to know if they anchor that stand? I know that even a cropped prop will make some good thrust.

dirwin · Posted: Tue Oct 05, 2010 12:31 Post subject:

The engines do not need anchoring. If they are mounted on a trailer, then the trailer brakes, with wheel chocks and a front stand is sufficient.

The prop blades are usually run at a high (stalled) pitch angle, and whilst they generate thrust they also generate a lot of drag to load the engine.

I have Merlin, whose prop is set to 40 deg minimum pitch, and feathered as a max. At 40 deg, it is likely to generate significant thrust but (hopefully) not enough to present a problem. Torque from the prop is ultimately the larger constraint, as the engine stand/trailer needs to be resilient to high torque twist.