On a level keel they now darted ahead at greater speed as Lieutenant Larson turned on more gasolene. Then, when Dick had become a little used to the novel sensation, they showed him how to work the different levers. The motor was controlled by spark and gasolene exactly as is an automobile. But there was no water radiator, the engine being an up-to-date rotating one, and cooling in the air. The use of the wing-warping devices, by which the alerons, or wing-tips are "warped" to allow for "banking" in going around a curve, were also explained to Dick by means of the levers controlling them.
You know that a horse, a bicyclist, or a runner leans in toward the centre of the circle in making a curve. This is called "banking" and is done to prevent the centrifugal force of motion from taking one off in a straight line. The same thing must be done in an airship. That is, it must be inclined at an angle in making a curve.
And this is accomplished by means of bending down the tips of the planes, pulling them to the desired position by means of long wires. It can also he accomplished by small auxiliary planes, called alerons, placed between the two larger, or main, planes. There is an aleron at the end of each main wing.
Straight ahead flew the army men and Dick, and then, when the cadet was more used to it, they went around on a sharp curve. It made the young millionaire catch his breath, at first, for the airship seemed to tilt at a dangerous angle. But it was soon righted and straightened out again.
Suddenly a shadow seemed to pass over Dick's head. He looked up, thinking it was a dark cloud, low down, but, to his surprise, it was the other army craft flying above them.
"A race!" thought Dick, and he wondered how his chum Paul was faring.
There was an impromptu race between the two aircraft, and then they separated, neither one gaining much advantage. Back and forth they went, over the school grounds, and then in circles. Dick was rapidly acquiring knowledge of how to operate the big biplane.
"We'll go down now!" spoke the captain, though Dick could not hear the words. The young millionaire made up his mind that he would have a muffler on his airship, and also more room to move about. He intended to make rather a long flight.
The deflecting rudder was tilted downward, and the descent began. They were some distance out from the Kentfield grounds now, but were headed for them on a long slant. Dick wondered if they would reach them.
At a nod from the captain, Lieutenant Larson reached up and shut off the motor. The sudden silence was startling.