My prop of choice on the DA 50 is the Menz 22 x 8 or if the supply is dried up the NX in the same size is a great substitute. The Menz 24 x 8 is a bit large for the 50 IMO but the engine will swing it but the rpm's will be down, mine makes about 6600 on the 24 x 8, about 7200 on the 22 x 8.

Dick Hanson has posted often on the subject and if you call DA they will repeat his sentiments. Two strokes need to rev for max power and running too large a prop is counter productive towards that goal. If you want to 3D anything but the lightest airframes with this engine stick with the smaller props that will allow the rpm's to stay up.