There are a lot of helicopters that fly around where I live. I never noticed until two couch surfers from Oregon brought it to my attention, but you can constantly hear the buzzing of a helicopter just about everyday. I’ve come to the conclusion that this phenomenon is directly correlated to the large number of medical facilities in the area. The helicopters are probably medevac either training or rescuing someone. A girl in my freshmen dorm room actually had to be medvaced after a nasty car crash. It was probably one of the helicopters that fly around all the time.
I’ve always wondered how helicopters work. I know it spins propellers and rotors to induce lift, but how do the rotors turn fast enough? Helicopters are pretty heavy. The answer is not as complicated as I would have imagined. An engine or pair of engines will turn a draft shaft which is connected to a gearbox. Gearboxes are a speed reducer that decreases motor speed through an increase in torque. They are used in numerous industries and applications. The gearbox attached to a driveshaft will shift the rotation angle from vertical to horizontal and passes the power on to the transmission.
Helicopters are not the only machine/vehicle to use gearboxes. They are used extensively in the agricultural industry as well. Tractors, forage spreaders, food & processing plants and snow blowers all utilize gearboxes to increase torque. It all operates on gear ratios. A larger input gear is attached to the engine. This toothed gear turns an output gear that is attached to a machine part or in this instance, the helicopter blades. Get the blades spinning fast enough and a rotational force will lift up the helicopter, allowing it to soar through the air.