Penfield was delighted. Excitedly he explained his crude little model to Harry. And Harry saw that the novel motive power which he had used held vast possibilities. He wound up the spring and found that the power sustained the propeller in rapid motion for thirty-four seconds.
“Twelve seconds is the best ever done with elastic band torsion,” said Penfield. It was evident that he had been studying the subject.
“Well, then,” said Harry, in a brown study. “I don’t see why we should lose those twelve seconds. Let’s see, twelve and thirty-four make forty-six. Forty-six seconds in the air will beat any model airship ever made. Say that you lose six seconds for the transfer of power—there you have forty left.”
“What do you mean?” asked both boys.
“Why, see here. The way they run these things usually—those you buy as well as the home-made ones—is by a long, thin strand of elastic from the axis of the propeller to a stationary hook. Wind the propeller and it winds the elastic—there’s your power. Now, see this little jigger here?” He put his finger on the upright wire bar on which the striker of the alarm had been mounted. “This vibrates rapidly while the spring is unwinding. Now, suppose you bend the top of it into a hook, wind up your elastic, then wind up your spring. This striker bar will hold the wound spring stationary until the power of the elastic is exhausted. As soon as the elastic is run down, the spring goes to work. There are half a dozen ways to connect the spring movement with the propeller—the catch chain is one. You’ll have to work it out. I give you the tip—the name is also thrown in—it’s the celebrated Strikastic Multiple Motor, producing a sustained flight of about forty seconds. ‘Strike’ stands for striker; ‘astic’ for elastic.”
“Or you might call it the Clockubber Transfer Motive System—that brings in clock and rubber,” said Gordon. “Or better still, the Penalarm Torsubber Champastic Double Motor—there you’ve got everything in—Penfield, Alarm, Torsion, Rubber, Champlain, Elastic and—and—wait a minute—”
“No aeroplane could carry such a name as that,” said Harry, “it would keel right over. Now, old boy,” he said to Penfield, “if I were you, I’d take time and make this right, and I believe you’ll have a winner. Make your plane bigger—thirty inches anyway, and flex it. You take a wooden pie plate and see how much higher it goes than a flat disk.
“Flex it this way” (he showed with pencil and paper); “then if I were you I’d have the sticks of your motor-base, or backbone, as you might call it, just wide enough apart to wedge this clockwork business between; it’ll stand rigid and you’ll get rid of a lot of friction. You might take away the brass frame altogether and line the wooden casing with aluminum. You’ve got to have the spring farther aft than this so as to have a good long span of elastic. I don’t know what will happen up in the air when the power is transferred. Your propeller will probably slow down a second or two; you’ve got to experiment with that. Your difficulty is going to be in utilizing the power supplied by the spring by some light, simple mechanism. Cogwheels eat up a lot of energy—but there’s a way, as my old college chum here would say, and it’s up to you.”
The boy stood radiant as they rose to go.
“Did you think of using the alarm apparatus?” Harry asked him.