There are many forms of such planes this year which are marvels of lightness and strength, but the beginner should try the simplest. Begin by building a simple rectangular frame, three feet in length and ten inches in width of half-inch or quarter-inch strips. Mortise the corners half way through each stick and glue them in position. Increase the steadiness of the frame by a cross piece at the center, without mortising. Mount your motor above the frame, selecting some simple, strong support for the axle and the anchorage.
A model which rises unassisted requires considerable power and your propellers should have eight-inch blades and be carved from blanks one inch thick. You may find it advisable later on to install propellers with very broad blades. First install motors of considerable power, each consisting of twelve or fourteen one-eighth-inch rubber strips. You will not get more than two or three hundred turns out of them, but with a high-pitch propeller this will give you an excellent flight, say 200 feet.
Model With Minimum Plane Surface.
For the early trials use planes with a rather high aspect ratio. Make one of the planes four by sixteen inches with square corners, and the second, which will be carried forward, about the same size with rounded corners. Both planes should have a slight camber.
Attach the planes to the under side of the motor base. The theory of this adjustment is that the planes thus rest upon undisturbed air and are more stable. The planes above the frame come in contact with air which has been churned up more or less by the passage of the frame. A small vertical rudder may be added below the rear frame and well back of the center of gravity. The model should be supported at a slight elevation by a simple skid. By adjusting the angle of the forward plane, this model may be made to perform a number of spectacular flights. A model very similar to this was the winner of a cup offered for the best spectacular flights at an important New York tournament.
A SIMPLE EXPERIMENTAL MODEL.
A great deal of pleasure and profit may be had from a small experimental model aeroplane. The beginner who is constructing his first model will find a small machine by far the most satisfactory. The more experienced model builder, on the other hand, will find that so simple a model will enable him to try out new theories quickly and cheaply. A simple Bleriot form, one foot in length, driven tail foremost is recommended. Many successful model builders keep such a model constantly in their workshops.
A model aeroplane of this type and size can be made to fly from the very first. Many of the problems which appear so difficult in constructing a three-foot model, such as balance, head resistance, and the proper adjustment of power, practically are avoided in this miniature aeroplane. There is a great advantage again in the fact that the small model may be flown indoors in the average room, where the air problems are almost negligible. Fig. B.
Let the motor base consist of a single stick one-fourth or three-eighths of an inch square and one foot in length. At one end of the base, attach a block of wood one inch square and of a thickness equal to that of the stick. Glue this in position and bind it securely by wrapping with thread touched with glue. At a point three-quarters of an inch above the stick, drill a hole parallel to the frame for the axle of your propeller. A hooked wire should be attached to the opposite end of the base. One end may be run through the stick and fastened, or it may be imbedded in a block fastened to the stick corresponding to the axle block. A simple and effective motor anchorage may be made of metal (described elsewhere).