Rudy Reeves, age 9, of Columbia, Tenn., for his question:
WHO BUILT THE FIRST HELICOPTER?
Aviation historians disagree on who made the first manned helicopter flight. Some give credit to a French mechanic named Paul Cornu who flew his two rotor helicopter in 1907. Others say it was a French inventor named Louis Breguet with a four rotor helicopter in the same year.
Both made short flights but neither was practical. Their flights were wobbly and could not be controlled.
The first truly successful helicopters were developed during the 1930s. In 1937, a German named Heinrich Focke flew for more than an hour and went up to 8,000 feet. And then in .1939, a Russian living in the United States named Igor Sikorsky built and flew the first practical single rotor helicopter.
The idea for the helicopter turned up hundreds of years ago. The great Italian artist and scientist Leonardo da Vinci drew sketches of a flying machine of this type, and even earlier the Chinese made toys that flew like helicopters. The Chinese "flying tops" had rotors made of feathers.
In 1784, two Frenchmen named Launoy and Bienvenu built a model helicopter that flew. Their model was based on the Chinese idea and it had two rotors made of feathers. One rotor was mounted at each end of a shaft. The spring action of a piece of whalebone made the rotors spin in opposite directions.
One of today's helicopter's actually uses its rotor blades as wings. The word helicopter itself refers to the action of the rotor blades. It comes from the Greek words helix, meaning spiral, and pteron, meaning wing.
The pilot controls the helicopter today by changing the pitch or angle of the rotor blades. To hover over the same spot or to go straight up or down, the pilot keeps all blades at the same pitch. To move forward, backward or sideways, the pilot tilts the rotor in the direction he wants to go.
Helicopters are sometimes called flying windmills, whirlybirds or choppers. They range in size from small one man models to large transports that can carry 30 or more persons.
Some helicopters have piston engines while others use gas turbines. Some can carry loads that weigh as much as 10 tons.
The type of helicopter powered by gas turbines is called a turbocopter or jet helicopter. The fastest of this type can fly more than 200 miles an hour.
A helicopter can do jobs no other vehicle can do. It can take off from or land on a clearing that is extremely small. It can even pick up or deliver cargo without landing at all.
Helicopters are valuable in all types of industry and public service jobs. The military also depends on them for transporting troops and equipment, rescue and observation.