Chapter 3

A SUCCESSFUL MODEL

Mr. Giddings was glad to accept the invitation to the trial flight. He and his son met the Ross boys at the old race-course Saturday afternoon. This immense, level field, with its one-mile oval and great empty sheds, at one time had been the county's boasted fair-grounds, but two years prior to the opening of our story it had been sold to Mr. Giddings, whose residence property stretched down the side of Shadynook Hill and joined it. New fair-grounds had then been established in another and more centrally located section of the district. In the old grounds the boys of the neighborhood now went to fly their kites and model airplanes, to hold impromptu bicycle and foot races, and to play tag and hide-and-go-seek in the cavernous sheds and around the numerous sagging stables.

It was late in the afternoon--just before dusk, when the winds would be at their quietest, and others not likely to be present--that our friends arrived at the field. There was not a soul to be seen. Paul, who had carried his precious Sky-Bird, freed it from the wrapper and held it up for Mr. Giddings to see. The night before he and John had put the finishing touches to the delicate structure by adding another coat of varnish and attaching the little rubber-tired aluminum wheels to the axle.

As Paul now held it up before the gaze of the great newspaper man, Mr. Giddings made no effort to restrain his admiration. "What a little beauty!" he cried. "Why, it's almost a perfect mechanical representation of a bird!"

"Isn't she a dandy, dad?" put in Bob, his eyes snapping.

"The Sky-Bird is really more of a bird than you may think, Mr. Giddings," declared Paul.

"Yes," added his brother John. "As you probably know, sir, a bird gets its great buoyancy from the fact that every bone in its body is hollow; in flight it fills these bones with a very light gas, which is formed by an action of its lungs in drawing in air. We have adapted this principle in the wings and fuselage of this little machine. They are airtight and filled with compressed helium-gas, which is non-inflammable and nearly as light as its highly volatile rival, hydrogen-gas."

"Hydrogen-gas is surely a dangerous commodity around fire," said Mr. Giddings. "I understand that when the big English dirigible R-34 came across the Atlantic last summer she was filled with hydrogen, and that her commander and crew all wore felt-soled shoes, so that they would not by any chance cause a spark when they walked over her metal floors and ladders just beneath her great bag."

"That is true," vouched John Ross. "One little spark reaching any of that stored hydrogen would have torn that great dirigible into fragments in one gigantic blast."

"We have handled recent newspaper copy containing mention of this new gas, helium; but I must confess I am in the dark regarding its nature and source," said Mr. Giddings. "What is it, anyway?"

"I will refer your question to Paul here," replied John. "He is the one who worked out this idea of using helium in an airplane and giving it the best properties of a dirigible without any of the dirigible's handicap of clumsiness and excessive wind resistance. He has been studying the properties of helium in school, also the flight of birds."

"Well, not to get into a tiresome discourse, as Professor Herron would say, I shall make this description very rudimentary," said Paul, with a smile. "During a total eclipse of the sun in India in 1868, Lockyer, a British astronomer, saw in the spectroscope a bright, yellow line of light around the sun. He called it _helium_, after the Greek word for sun. So much for him. Twenty-seven years later an element was found on earth in natural-gas in Kansas, which gave the same bright, yellow light viewed through the spectrum. The people, finding it would not burn, disgustedly let millions of barrels of this valuable element escape into the air, before a scientist told them that it was of untold value for balloon and airship purposes. It is thought the gas comes from radium deposits. It has never been found in any country except the United States, and only here in Kansas and northern Texas, where it occurs in sands from 14,000 to 16,000 feet deep. Our government is now securing about 50,000 cubic feet of helium per day, refusing to sell it to foreign countries, as it is all needed here, besides which it might be used against us in case of another war."

While Paul had been telling this, Mr. Giddings had been busy jotting something down in shorthand in a notebook.

"Pardon me, Paul," he said, looking up with a smile, "but this is so mighty interesting that, before I knew it, my old-time reportorial instinct had gotten the best of me, and I found my pencil at work. If you have no objection I should like to use this in the columns of the _Daily Independent_ some time when it seems to fit in."

"No objection at all, sir," assured Paul.

Mr. Giddings began twirling the little twelve-inch two-bladed propeller at the nose of the model airplane. "What do you use for power to turn this propeller?" he asked, after admiring its perfect proportions for a moment. "I don't see any rubber-bands, such as Robert here has always used on his little machines."

John deftly lifted off the thin veneer hood of the airplane, and disclosed a very small four-cylindered rotary pneumatic engine of bewitching simplicity and lightness, which a baby could have held out in its pudgy palm.

"Paul has worked this little motor out of aluminum and brass and steel, from odds and ends," said John.

"With more or less help on the part of my elder brother," interjected Paul.

"Well, perhaps with a little," admitted John, "more suggestive than otherwise."

"What sets it going?" questioned Bob, curiously.

"The fuselage is divided into three sections," said Paul. "The forward section contains the engine here; the rear section is an airtight chamber containing helium; and the central section is also an airtight chamber, but contains ordinary air which has been pumped into it through a valve, using the bicycle pump John is carrying, until it is under strong pressure. When I turn this little valve an outlet is opened for the air to escape by a tube into branches communicating with each of these four cylinders. This works the tiny pistons, much the same as gas in a gasoline-motor, and they turn the little crank-shaft to which they are connected, and the crank-shaft in turn revolves the propeller on its end."

"Wonderfully simple!" Mr. Giddings exclaimed. "Wonderfully ingenious, too! Is this your invention, young men?"

"Partly, sir," replied Paul. "I understand, a company in New York is making a somewhat similar pneumatic motor for model airplanes, but John and I have made some radical improvements, to our notion. To-day's test will tell the story."

"Let's see the propeller spin 'er up once for the fun of it," suggested Bob. "It won't do any harm, will it? Dad and I will hold on to the airplane."

"Get a good grip then," warned John Ross, "for you will find there's a terrific pull to the little rascal. Paul and I tried her in that fashion early this morning down in the basement."

Bob and his father secured firm holds of the little Sky-Bird, one on each side, where the propeller could not strike them.

"Ready?" asked Paul, with a smile.

"Ready!" came the answer in unison.

Paul touched the little valve in the tank chamber of the fuselage. The next moment there was a quiver, and then the propeller began fairly to hum. A strong, steady gust of air began to blow in the faces of the Giddingses, while they had to hang on grimly in order to keep their little charge from jumping out of their arms and dashing away into the air. For fully three minutes the propeller continued to whirl with undiminished speed, then slowly it began to slow up, and finally stopped.

Both Mr. Giddings and his son wiped their hot brows as they handed the plane over to its makers.

"Whew!" said Bob, "that little mule has got a lot of pull to her."

"That she has," supplemented his father. "What sort of material is her frame made of?"

"Balsa-wood," said John.

"I never heard of that. Is it something new?"

"Yes,--to the arts of civilization, but I presume it has been used by the Indians of Ecuador, where it grows, for scores of years in the making of rafts, for which it is particularly well adapted. The tree looks much like our southern cottonwood, and the wood apparently has no grain. It has a surprising toughness and strength, and is a trifle over half the weight of cork, weighing only 7.8 pounds per cubic foot, while the same sized piece of cork weighs 13.7 pounds."

"Has this wood ever been used in constructing full-sized airplanes?" asked Mr. Giddings.

"I think not; but Paul and I believe it will be the coming wood for them," said John with enthusiasm. "We have used it plain on this machine. On a large airplane it ought to be reinforced with transverse sections of very thin spruce laid latticewise. That would add considerably to its natural strength, and increase the total weight very little."

"H'm, h'm!" said the great newspaper publisher, "this is very interesting, I am sure. Now let us see how this little affair behaves itself in the air."

Paul and his brother led the way out into one corner of the big field, so as to bring what slight breeze might spring up into the head of the airplane, explaining that machines without a pilot would keep a better keel under such conditions. John then carefully attached the bicycle-pump and recharged the air-tank, following which he took out his watch to time the flight. Mr. Giddings and Bob also took out their watches.

Paul set the little Sky-Bird down on the hard earth, in a spot where there was no grass or other obstacle, and with his finger on the air-valve, said: "Practically all rubber-band motors require starting the model airplane off by picking it up and tossing it away from you up into the air; but I think this machine will rise from the ground like a large plane, on account of its great lightness and unusual power. We will now see if I am right."

To tell the truth, this being the first time he had really tried the Sky-Bird in a flight, Paul was nervous as he turned the valve, removed his hands from the graceful little plane, and straightened up.

With a whirr like the wings of a partridge as it is flushed out of the grass by the huntsman's dog, the small machine shot forward a few feet over the smooth ground, then gracefully arose in the air and started away toward the opposite corner of the field. As it proceeded it continued to rise, until it reached a height of possibly ninety or a hundred feet, when it began to dip unsteadily.

"It's a gust of wind striking it," remarked John uneasily. "I hope she weathers it. If there was only a pilot in her now, he could----"

But even as he spoke the Sky-Bird seemed to recover her balance. Making a pretty circle, away she sped on her course, neither rising nor falling. Like a real bird she sailed onward, the noise of her whirring propeller now lost to her fliers, but her little pale-yellow silk wings against the blue sky plainly tracing her course for them. Paul was running after her now as fast as his legs could carry him. What if she should keep right on and go over the far fence?--he might lose the little darling!

That fence was a good half-mile away. For his pet to cover such a distance had not seemed within the bounds of probability to either himself or John at the start, for all of their great confidence in the flying powers of the new model. Now, as he kept on running and the Sky-Bird continued going with no sign of dropping, Paul really became alarmed for her safety in landing.

But just before it reached the boundary of the grounds, the youth saw that the airplane was slowly settling. Into the next field it flew, and the high board fence shut it from Paul's view as he came up to it. With a jump he caught the top boards, and scrambled up, springing down on the opposite side. It was to see his little machine just miss the branches of an oak tree and settle down into some long grass about a hundred yards beyond.

He found it undamaged, and hurried back to his friends in the fair-grounds, his heart beating jubilantly at the splendid results of the flight. He hugged the small airplane to his heart as if it were the most precious possession in the world, as indeed it was to him.

Mr. Giddings and Bob were loud in their praise, and John smiled in that quiet way that told the younger brother how well pleased he was. It was found that the Sky-Bird had passed over the lower fence in just one minute and three seconds, which was certainly good speed for such a diminutive contrivance. Several other flights were then made, all of which were equally successful. At the conclusion Bob Giddings was so excited that he could hardly stand still.

"Dad, isn't this little thing simply a wonder?" he exclaimed. "I'd give anything in the world if I could own a big fellow built on this principle. I'll bet it would pass anything now made."

His father looked thoughtful for a moment. Then, turning to the Ross brothers, he observed:

"Do you think, boys, that these features could be successfully applied to a full-sized airplane?"

"There's no doubt at all about it, to my mind, sir," replied John Ross. "That's the next thing Paul and I propose doing, although I expect we shall have a hard time getting enough money to meet the expense of materials. Of course we shall have the regular type of gasoline engine in place of this pneumatic arrangement, as this principle won't apply to big machines. I figure a 400 horse-power Liberty engine would carry such a machine two hundred miles an hour."

Again Mr. Giddings was silent a moment. Then he resumed: "John, I hear that you have been laid off from your Air Mail job. Is that right?"

"It is, sir."

"Well, then, I am going to make a proposition to you and Paul, and in a way Robert may consider himself involved, too, I expect. As you may know, Robert plans to be an electrical engineer, and Mrs. Giddings and myself are anxious to encourage him in every way we can. For some time he has been experimenting with wireless telegraph and telephone apparatus, and has made some sets of the latter which it seems to me are an improvement over anything now on the market, particularly a set for airplane use, which he has no means of properly testing out on account of the lack of the airplane. Now my proposition is just this: I will meet every expense of making a first-class full-sized airplane like the Sky-Bird, and pay you, John, a wage equal to that which the government allowed you as a pilot, if you three young men here will do the construction work secretly, and if Robert may be allowed a one-third interest in the venture, both in the plane to be made, and in any future benefits to be derived from the patent rights."

Of course the delighted John and Paul accepted this splendid offer, and Bob Giddings was so happy at the prospect of a fine big airplane in which to install his wireless apparatus that he actually hugged his father. They repaired to the Giddings home, and there, in true business form, a contract was drawn up and duly signed by all interested parties, with a notary's seal attached.

With a copy in their possession, the Ross boys hurried home, after having dinner with the Giddings family, to acquaint Mrs. Ross with the good news.