RE: Prop for da-50
First things first.
For all of those that have been using Zinger and Master Airscrew types of props with 50cc engines, get rid of them!! Stir paint, shim a door frame, whatever, but get rid of them.
When you stepped up to higher performance giant scale planes and gas engines you made a substantial investment in the progress of your abilities. Why is that progress and performance being limited by a poor prop selection? Price? I sure hope not. You invested more than you probably ever had before, so a few bucks more for a good prop should not break the bank. When you moved up to gas engines in this size range and above, you should also move up in prop performance. The difference between a Mejzlik, Menz, NX, BME, MSC, Bolly, Bambula, and other upper level props compared to Zinger and Master Airscrew is like night and day. Avoid the usual plastic type props as well.
You will be in utter amazement when you find out what you have been missing[X(]