Now suppose the aviator is flying horizontally and wishes to climb. At the rear of the machine and forming part of its tail is a hinged horizontal flap called the “elevator,” under the control of the pilot. By giving this flap an upward tilt he causes the air to exert a downward pressure on the tail of the machine, and hence the nose of the machine is carried upward. While the inertia of the aeroplane tends to carry it along the original path, its wings now present a greater angle to the air, the lift is increased, and the machine rises. The reverse of this operation will cause the machine to descend.
The Bed of Potomac River, at Washington. From an altitude of a few hundred or a few thousand feet, submarine features are clearly revealed to great depths. Objects have thus been photographed 45 feet under water. The shoals are submerged to a depth of from 2 to 5 feet. In favorable weather, aerial photographs are valuable in making hydrographic surveys. (Photographed from the air by Dr. W. T. Lee, U. S. Geological Survey.)
A vertically hinged flap in the tail, acting on exactly the same principle as the rudder of a ship, enables the pilot to turn horizontally. Two or more small horizontal flaps, known as “ailerons,” attached to the wings, are used to preserve the lateral balance of the machine, and to give it the proper “bank,” or inclination, when making a turn.
Drilling with Compressed Air in a Copper Mine. The drill also forces a stream of water into the hole to lay the dangerous sulphur-bearing dust. (Courtesy Sullivan Machinery Co.)
Launching a Weather Bureau Kite from the “Seneca” During the International Ice Patrol, to Explore the Air Over the Ocean.
(Photograph, U. S. Weather Bureau.)
With these few details in mind, we shall be prepared to consider, in a general way, how the behavior of an aeroplane is affected by the wind and other atmospheric phenomena.