The parts composing the frame were made first, and all small details, such as rudder, propeller, tilting plane, etc., cut out later.
The separate parts are shown in the drawing. Four straight pieces like a were required to support the tilting plane in front, and two pieces each b and c for the rudder in the rear. Two pieces a, one of b and c were fastened together by means of two uprights d, forming one complete side of the machine. This was completed, and the second side made identical with it.
These two sides were then fastened parallel with each other, rigidly, by means of the two rudder posts e e and the cross pieces f f, by brads. The rudder posts bound the two sides rigidly at the rear, the cross pieces at the centre, and at the forward end the tilting plane was held in position by the brads, which also acted as pivots.
This made a remarkably light and yet strong framework. The card-board planes were not placed in position until everything else was finished, as they could be attached easily and quickly, but were very much in the way when experiments were being made on the propelling apparatus.
Of course there had to be a propeller, and the problem of making it required some practice.
Ralph introduced the subject by showing Harry how to make an old-fashioned toy, shown in the detail drawing, of two pieces, one the propeller, the other a balancing stick.
The propeller was made of a piece of 3⁄8-inch basswood, 4 inches long and 1⁄2 inch wide. A 3⁄16-inch hole was first drilled at the exact centre. The two ends were then whittled down to the shape shown at k. The balancing stick was next whittled down until one end fitted tightly into the hole drilled in the propeller, and the rest of the stick then rounded until it was of uniform diameter. This stick was glued into the hole, and allowed to dry.
There was plenty of work to do while the glue was hardening, as the cross pieces g g had to be fastened to the frame to prepare for the installation of the power plant.
When the glue was dry, Ralph took the balancing stick between the palms of his hands, drew his right hand toward him with a quick motion, at the same time releasing the stick. To Harry's amazement, the whole thing flew up and struck the ceiling, and for a few minutes aeroplanes were forgotten while the two played with this interesting but ancient toy.