My P-51 is on its 19th season ( probably has 600 flights ). I have a G-62 with monocote covering. Robart retracts. Weighs 24.5 lbs. Has been clocked @ 105 MPH. Mine balanced perfectly with the G-62, muffler, spring starter, vibration mount, so keep the tail light or you'll have to add nose weight. I also use a 6v 2400 mAh NiCad battery. You'll have to cut at least a 1/2" off the gear covers if you fly off of grass. I use full flaps to land, ( all throws are as reccommended in the instructions ). The G-62 has the same spinner back plate to motor mount distance as the US 41 shown in the plans. Used to use a 20 x 6-10 prop but the engine has broken in so well that I had to go to a 20 x 8-14 to keep the prop noise down. Probably a little faster too. I have flown formation with a DA 50 plane and they are very similar in speed.