Tom Swift and His Air Glider | Page 5

adjusted the muffler, and most of the noise stopped.
"Come on back, and finish pumping up the tires," he shouted to Ned. "I'm going to stop her now, and then I'll give her the pressure test, and we'll take a trip."
Having cleared his eyes of smoke, Ned came back to his task, and this having been finished, Tom attached a heavy spring balance, or scales, to the rope that held the airship back from moving when her propellers were whirling about.
"How much pressure do you want?" asked Ned.
"I ought to get above twelve hundred With the way the motor is geared, but I'll go up with ten. Watch the needle for me."
It may be explained that when aeroplanes are tested on the earth the propellers are set in motion. This of course would send a craft whizzing over the ground, eventually to rise in the air, but for the fact that a rope, attached to the craft, and to some stationary object, holds it back.
Now if this rope is hooked to a spring balance, which in turn is made fast to the stationary object, the "thrust" of the propellers will be registered in pounds on the scale of the balance. Anywhere from five hundred to nine hundred pounds of thrust will take a monoplane or biplane up. But Tom wanted more than this.
Once more the motor coughed and spluttered, and the big blades whirled about so fast that they seemed like solid pieces of wood. Tom stood on the ground near the levers which controlled the speed, and Ned watched the scale.
"How much?" yelled the young inventor.
"Eight hundred."
Tom turned on a little more gasolene.
"How much?" he cried again.
"Ten hundred. That'll do!"
"No, I'm going to try for more.
Again he advanced the spark and gasolene levers, and the comparatively frail craft vibrated so that it seemed as if she would fly apart.
"Now?" yelled Tom.
"Eleven hundred and fifty!" cried Ned.
"Good! That'll do it. She'll give more after she's been running a while. We'll go up."
Ned scrambled to his seat, and Tom followed. He had an arrangement so that he could slip loose the retaining rope from his perch whenever he was ready.
Waiting until the motor had run another minute, the young inventor pulled the rope that released them. Over the smooth starting ground that formed a part of the Swift homestead darted the aeroplane. Faster and faster she moved, Ned gripping the sides of his seat.
"Here we go!" cried Tom, and the next instant they shot up into the air.
Ned Newton had ridden many times with his chum Tom, and the sensation of gliding through the upper regions was not new to him. But this time there was something different. The propellers seemed to take hold of the air with a firmer grip. There was more power, and certainly the speed was terrific.
"We're going fast!" yelled Ned into Tom's ear.
"That's right," agreed the young inventor. "She'll beat anything but my Sky Racer, and she'd do that if she was the same size." Tom referred to a very small aeroplane he had made some time before. It was like some big bird, and very swift.
Up and onward went the remodeled airship, faster and faster, until, when several miles had been covered, Ned realized that the young inventor had achieved another triumph.
"It's great, Tom! Great!" he yelled.
"Yes, I guess it will do, Ned. I'm satisfied. If there was an international meet now I'd capture some of the prizes. As it is--"
Tom stopped suddenly. His voice which had been raised to overcome the noise of even the muffled motor, sounded unnaturally loud, and no wonder, for the engine had ceased working!
"What's the matter?" gasped Ned.
"I don't know--a breakdown of some kind."
"Can you get it going again?"
"I'm going to try."
Tom was manipulating various levers, but with no effect. The aeroplane was shooting downward with frightful rapidity.
"No use!" exclaimed the young inventor. "Something has broken."
"But We're falling, Tom!"
"I know it. We've done it before. I'm going to volplane to earth."
This, it may be explained, is gliding downward from a height with the engine shut off. Aeroplanists often do it, and Tom was no novice at the art.
They shot downward with less speed now, for the young inventor had thrown up his headplanes to act as a sort of brake. Then, a little later they made a good landing in a field near a small house, in a rather lonely stretch of country, about ten miles from Shopton, where Tom lived.
"Now to see what the trouble is," remarked our hero, as he climbed out of his seat and began looking over the engine. He poked in among the numerous cogs, wheels and levers, and finally uttered an exclamation.
"Find it?" asked Ned.
"Yes, it's in the magneto. All the platinum bearings and contact surfaces have fused and crystallized. I never saw such