Lego Technic 42020 Twin Rotor Motorized Helicopter

I got this awesome LEGO Technic Twin-rotor helicopter! The video is time lapse so it looks like I am building the helicopter like a master builder. Towards the end of the video, I attach a 9V LEGO train motor to the helicopter. The blades spin super fast but the helicopter can’t take off. But, the helicopter moves a little bit by itself. I’m not kidding! It turned a little bit. See if you can find the part when it moves. No remote. No IR receiver.

Check it out: