The weight a having now ascended as far as possible forward in its swing, and its motion checked by the banking action of the plan it will again swing back, and again carry with it the frame, thus setting up an oscillation, which is extremely dangerous.
The tail E, with its unchanged angle, does not, in any degree, aid in maintaining the frame on an even keel. Being nearly horizontal while in flight, if not at a negative angle, it actually assists the forward end of the frame to ascend.
APPLICATION OF THE NEW PRINCIPLE.—Extending the application of the suggested form, let us see wherein it will prevent this pendulous motion at the moment the power ceases to exert a forwardly- propelling force.
Fig. 21. Synchronously moving Planes.
In Fig. 21 the body A is shown to be equipped with the supporting plane B and the tail a, so they are adjustable simultaneously at the same angle, and the weight D is placed below, similar to the other structure.
At every moment during the forward movement of this type of structure, the rear end of the machine has a tendency to move upwardly, the same as the forward end, hence, when the weight seeks, in this case to go on, it acts on the rear plane, or tail, and causes that end to raise, and thus by mutual action, prevents any pendulous swing.
LOW WEIGHT NOT NECESSARY WITH SYNCHRONOUSLY-MOVING WINGS. —A little reflection will convince any one that if the two wings move in harmony, the weight does not have to be placed low, and thus still further aid in making a compact machine. By increasing the area of the tail, and making that a true supporting surface, instead of a mere idler, the weight can be moved further back, the distance transversely across the planes may be shortened, and in that way still further increase the lateral stability.
CHAPTER V
DIFFERENT MACHINE TYPES AND THEIR CHARACTERISTICS
THERE are three distinct types of heavier-than- air machines, which are widely separated in all their characteristics, so that there is scarcely a single feature in common.