This is a useless thing. You can only experience extreme slowness. AG1: main engine Ag2: bottom rotary engine Ag3: mezzanine rotary engine AG4: upper rotating engine Ag5: propeller Slow down experience method: AG1 rises to a height (not too high recommended, or it will fall for a long time) Then close the thrust, close AG1, open AG4, 5 and open thrust. You can experience extreme deceleration. If all the engines are shut down at this time, you will experience the extreme deceleration without oil. Related links: Katyusha (historical version): https://www.simpleplanes.com/a/v6iAM3/Katyusha-Rocket-Launcher For a better use of simpleplans in the world: https://www.simpleplanes.com/a/gIA7n3/Katyusha-Modified