switch26,
I'm very safety conscious and wouldn't feel right if I didn't say something about the chair with weights on it. Even with the 40lbs of weight on the chair, the DL50 will probably still move it. It is just the friction between floor and the feet of the chair that is holding the plane back, not the total weight on the chair. Tie the plane to something heavy. Do yourself a favor and start listening to the people in this thread, otherwise you or someone else is going to get bit by the prop!!! Another thing, you say you never went over quarter throttle, the throttle curve on a gas engine is non-linear. When you are at a quarter of the stick movement, you probably are around half throttle on the carb which is probably 60-70 power.
Chuck