Modern entry level RC sailplanes/gliderplanes use a very simple architecture - there are no moving parts other than the two propellers. When you accelerate the plane ascend. When you deccelerate the plane descend. When you want to make a right turn the left motor pushes harder than the right one, and vice versa. You can let it take off from the ground, or simply let it start by hand throwing. A simple but effective 2 channels design. For starters...