David Rumfelt, age 13, of Albuquerque, N.M., for his question:

WHAT IS AN AUTOGIRO?

An autogiro is a trade name for a type of airplane that was invented in the early 1920s by a Spanish aeronautical engineer named Juan de la Cierva The term is sometimes commonly applied to all planes that use the principle of auto gyration to provide lift.

The wings of an autogiro are rudimentary or nonexistent. The lift during flight is supplied by a large, multibladed rotor mounted above the fuselage. The plane is equipped with a conventional engine and propeller that pull it forward through the air. The forward motion causes the rotor to gyrate automatically, like a ,windmill.

The rotor of an autogiro, unlike that of a helicopter, is not connected with the engine during flight, except during takeoff in some models If such a connection is present, the craft is sometimes called a gyrodyne

The autogiro can ascend and descend very steeply and can take off and land on small fields

Autogiros were used during the 1930s for military liaison, delivering mail, exploration and agricultural purposes. They have now been generally replaced by helicopters.