Before revision: Introduction Traditional helicopters get both their propulsion and lift from the main rotor , and by using a dedicated propulsion device such as a propeller or jet engine, the rotor burden is lessened.Chandler, Jay.
After revision: Introduction Traditional helicopters get both their propulsion and lift from the main rotor ; by using a dedicated propulsion device such as a propeller or jet engine, the rotor burden is lessened.Chandler, Jay.