Hanger 9 P-51D Highspeed problem!
Well, I flew mine yesterday. Flies great at 8 lbs with the OS 91. I have the CG right on the money per the instructions. I may play with it a little since it has some slight trim changes with different throttle settings. May also look at about one thin washer of down thrust. After three flights I think that I will replace the mechanical retracts with some pneumatics and Robart struts that I have sitting around. The stock steel LG struts are way too soft and allow the model to sway right to left too much for my liking. One thing that I did notice on my plane that is rather interesting is that the model seems to move the tail a few degrees to the left and right in straight and level flight. I came to call this trait "hunting". Interesting because my H9 Edge 540 did the same thing. I got rid of most of the problem with the Edge by moving the CG around. I am inclined to believe that the root of the problem may be the CG location, so I am going to play with it and see what happens. I'll keep you posted.
Later, Ed