Several issues here. For one, you don’t really want to change your RPMs very much if at all. I highly recommend picking a set speed and just toggle on and off. Two, you need to bind your prop pitch to your throttle controls. Zero throttle equals zero angle of attack on your propellers. Max throttle equals 50 degrees of prop pitch (for airplanes). As far as the sweet spot for max prop pitch for a helicopter, you might want to do some research. I’d recommend building a prop plane before a helicopter. Less complicated and you’re not trying to find that perfect sweet spot for hovering. It took me a while to grasp this concept, just remember that your prop pitch controls your speed, NOT your RPMs or torque. RPMs rev up and down waaay too slow to ever be able to reliably control. Also, make sure to go ahead and deploy your props in the VAB/hanger and unbind prop braking so that’s one less thing to deal with on the runway. When your throttle controls are all the way down and your props are spinning at full speed you should be at a complete stand still. As you slowly throttle up your propellers will start to grip the air and you’ll get a much faster top speed and faster acceleration. Hope this helps. My gamer tag is Homedawgian if you’d like help on Xbox.