Various shots of a helicopter lifting off the ground.
Airmen inspect aircraft, it has rotors mounted on top of wings. Aircraft attempts take off. It lifts and moves forwards for about 20ft then drops. Title reads "It's a helicopter and relies for lift upon a single engine and the large twin screws you saw whirling around". C/U front of aircraft as engine is turned. Helicopter, engine running and rotors turning, lifts from the ground & drops again.
Safety print exists.