P51Tugboat,

I used a YS .91AC in mine with an on-board ignition and Robart retracts. I got concerned when I weighed it and discovered that it was a portly 10 pounds before I was to begin adding a bunch of scale details. As it turned out, my concerns were for naught as it flew beautifully throughout the speed envelope. In fact, I had so much fun flying it that I never did get around to adding all the other stuff.

I did my take offs at 1/2 to 3/4 throttle and flew the entire pattern at less than full throttle. With these throttle settings, the plane had good scale-like speed and performed all the maneuvers in a scale-like manner. The few times I opened it up it flew like it would break the sound barrier..........not what I wanted. But, the real plus to flying at lower engine speeds is that the engine sounds more scale-like, too. Remember, that P&W 2800 didn't turn but maybe 3,000 rpms.

Take your time and enjoy the build. Oh, and your choice of a .91 4-stroke is an excellent one. This is one of the best flying scale warbirds ever designed with not one fault. You are gonna have a ball!

Al