I know its called simpleplanes but people make helicopters and cars in this game. I think that they should add wheels for cars as well as suspension and car motors. My second idea is turbine engines for helicopters. With the new update making helicopters has become easier but it it is still difficult to make large helicopters due to the maximum propeller size as well as the hp. The hp isn't that much of an issue but the medium and high power propellers stick out of the top of helicopters and make them look awkward. One more thing I want to talk about.
Some people have been making propeller engines with two sets of blades I feel like this would be great for Simpleplanes and add to the realism of planes.