CHAPTER VIII
THE SKY-BIRD II
"Well, Mr. Giddings, what do you think of Sky-Bird II?" asked JohnRoss, one memorable day.
There was a smile of deep satisfaction on John's own bronzed featuresas he put the question, a smile which was duplicated on the faces ofhis three co-workers--Paul, Bob, and Tom Meeks. It was the latter partof March, Easter vacation week for Paul and Bob, and the two chums hadbeen working every one of the last three days helping John and Tom putthe finishing touches on the big new airplane. And now this Fridaymorning it rested gracefully upon its own rubber-tired wheels, itsgreat stretch of wings spread out as airily as those of a monster bird,its huge two-bladed propeller glistening like burnished silver, and itsbody running backward in a splendid symmetrical taper, to end at thewell-proportioned tail. Sky-Bird II was done at last.
Mr. Giddings was so lost in admiration at the beautiful lines of thecraft that he did not reply immediately to John's question. He had notseen it for almost two weeks, and in that time, under the onslaughts ofthe four boys, it had changed appearance in a striking way, numerousfinished parts having been connected and paint and varnish having beenapplied.
"All I have to say, young men, is that if she performs anywhere near aswell as she looks, I shall be thoroughly satisfied with the money Ihave invested thus far," declared the great newspaper man with anenthusiasm which he did not try to conceal. His eyes were shining, ashe walked around the craft looking at it from all sides. He rubbed hisfingers lingeringly over the smooth fuselage, and smiled quietly as heregarded the name "Sky-Bird II" lettered in large blue characters onher sides and underneath each long bird-like wing. Then he mounted afolding step and went through a neat door into the glass-surroundedcabin. This was deep enough to stand up in, and provided comfortableupholstered cane seats for the pilot and four passengers or assistants.All of these seats except the pilot's and observer's were convertible,forming supports for the swinging of as many hammocks, and in a smallspace at the rear was a neat little gasoline-burner, and over it abuilt-in cupboard containing some simple aluminum cooking ware.
"Well, I declare!" said Mr. Giddings in amazement at the convenience ofthings, "it looks as if you fellows hadn't left out a single itemneeded in a long and enjoyable cruise."
"There's nothing like being fixed up for all emergencies, sir," laughedJohn. "As you notice, we have everything for night-flying as well asday-flying. With such a machine as this there is no reason why a crewof four or five could not run nights as well as days, two operatingwhile the others sleep in the hammocks. Cold foods can be cooked orwarmed up on the gas-stove when needed, and the enclosed cabin protectsall hands from the worst effects of bad storms."
"Wouldn't this glass break in a hailstorm?" asked Mr. Giddings. "Itseems to be pretty thin."
"It is thin," said Paul; "that is to give it lightness. It might checksome in a hailstorm, but it could not break out, as it is made of twolayers of glass between which is cemented a thin sheet of celluloid."
"I think you had two Liberty motors here in the hangar when I was herelast. I neglected to ask you the power of these, and what you need twofor," observed Mr. Giddings. "I thought you said in the beginning thatyou considered one 400 horse-power engine of sufficient strength tocarry this plane at a fast clip."
"It is this way, sir," responded John. "The regular big biplane of thebomber type carries two propellers with an engine for each propeller.If one motor fails them when flying, about all the other is good for isto make a landing with. By reason of the great lightness of ourairplane one good 400 horse-power motor is all we need for pullingpurposes. But suppose this should fail, as any motor might do? Wecould not continue, any more than the other fellow, and would have tovolplane to the ground. Again, suppose we wished to fly continuouslymore than twelve hours? We could not do so, as such a steady run wouldheat the best motor and ruin it. These two Liberty motors, which wehave, overcome all these troubles. Both are so arranged that a simpleswitch connects and disconnects either one with the propeller, and bothcan be put at work at the one time if needed in a bad storm. If onestalls, the other can immediately be thrown in and a forced landingobviated. Moreover, if we could get fuel when needed, with thisarrangement I am safe in saying we could fly steadily day and night,resting one motor and working its mate, for a week or more."
"What is this?" As he spoke the publisher touched a peculiar-lookinghelmet hanging from a hook near the pilot's seat.
Bob laughed. "Why, don't you recognize the products of your talentedson, dad?" he cried, as he took the object down and clapped it over hisfather's iron-gray head. "That's my new wireless telephone headpiece,and right underneath it here is the mahogany cabinet containing thesending and receiving instruments. You see, these two wires run fromthe plug up to the receivers, there being one receiver in each side ofthe helmet, right over your ear, pressing against the ear tightly bymeans of a sponge-rubber gasket."
"A man looks like a padded football player with this thing on," saidMr. Giddings with a smile. "Why is a helmet required at all?"
"We wouldn't require it so much with these motors, as they are equippedwith a new kind of muffler which shuts out about four-fifths of thenoise other airplanes get," explained Bob. "But for all that there arealways noises in airplanes; for instance, they say the whirr of thepropeller when it is revolving about 1450 revolutions per minute, or atthe full speed of this one, makes quite a roar; so you see the need ofthe helmet to shut out all undesirable sounds possible. In ordinaryplanes the crew cannot talk to each other except by using phones orputting their lips to each other's ears and yelling at the top of theirvoices, according to what John and Tom tell me. But we don't expect tohave that trouble in this enclosed cabin and with this new mufflerworking, do we, fellows?"
"I'm sure we won't," said John.
"Not if I'm any judge," grinned Tom.
"Can you talk with a ground station when you're flying, say a couple ofmiles high?" asked Mr. Giddings, examining a transmitter attached to ayoked wire support which his son slipped over his shoulders.
"Farther than that. With this particular vacuum tube, which willamplify sounds three or four times over any other I have tried, weexpect to talk with ground stations or other aircraft at a distance ofthree thousand miles. Notice what a simple thing it is, dad," and Bobindicated a little glass bulb which looked a lot like an ordinaryincandescent light, but which had a peculiar arrangement of wires andsubstances inside.
"Is the transmitter or receiver made just like the ordinary kind?"asked Mr. Giddings.
"Practically the same, dad. The wireless transmitter, like that of thewire telephone, contains a sensitive diaphragm which your voice strikesand sets to vibrating. These vibrations compress and release a capsuleof carbon granules which agitate and set in motion an electricalcurrent in two magnets connecting with them. The magnets convey thesound-waves in the form of electrical waves, along wires out to the tipof each wing, where the wires hang down a little way. When a messagecomes in it is caught by a webbing of antennae wires in our wings."
"Then I suppose these sound-waves, in other words the words one speaks,run out of the end of these wires into the atmosphere?"
"Exactly, sir," agreed Bob. "That is, the electrical waves areprojected into the air and disturb this air in a way to make it pulsatein the same manner as your voice makes the diaphragm pulsate. Thesewaves are then carried through the atmosphere in every direction, andsooner or later reach the antennae wires of some station equipped toreceive them. Down these wires they dash, are registered and magnifiedin the wonderfully delicate vacuum tube, and from it are carried upinto the receivers at your ears."
"I should think they would be electrical impulses when they reach thereceivers," argued Mr. Giddings. "How can a person hear _words_ fromelectrical discharges?"
Bob smiled. "Easy enough, dad," he went on. "You see, this vacuumtube does the business. The electrical current agitates this inunison, and the impulses
are immediately converted into wordsagain,--and there you are!"
"I acknowledge my understanding now," admitted Mr. Giddings, with ahearty laugh; "but there's just one thing yet I want light on: Where doyou get your electrical current? It takes a dynamo to makeelectricity, else storage batteries. I don't see either."
"Come outside here a moment, dad."
Bob smiled as he led the little party out of the Sky-Bird's cabin.When they once more stood on the hangar floor, he pointed to a peculiarT-shaped object just beneath the nose of the airplane. This hadescaped the gentleman's observation until now.
"It looks like a small propeller with a torpedo sticking out from themiddle of it," laughed Mr. Giddings.
"So it does, dad," agreed Bob. "Well, that's our wireless dynamo. Youwill notice that the propeller faces ahead, like the big fellow here.When the airplane is flying, the rush of wind spins the fan at aterrific rate, its axle operates a little dynamo in this torpedo-likecase and manufactures electric current. The current then passes intothis small apparatus here with a bulb attached, which regulates thevoltage and sends it up to the instruments in a uniform flow, no matterat what speed the airplane may be going."
"That's a cheap way of getting current," declared the newspaper man,"and a mighty good one, too." He now changed the subject by asking:"How much do you suppose this machine weighs?"
"I have been in smaller ones which weighed, unloaded, as much as threethousand pounds," admitted John Ross, with a peculiar smile. "Put yourhands under the Sky-Bird's nose here and see if you can lift her, Mr.Giddings."
"Don't joke that way, John," expostulated Mr. Giddings. "Why, herengines are right above this portion of her, and I couldn't lift one ofthem alone."
"Just try it anyhow, dad," persisted Bob, who also wore that queersmile.
More to accommodate them than because he expected to accomplishanything, the publisher half-heartedly braced himself in a crouchingposition and pushed upward on the airplane's front. To his amazementthe whole forward part of the machine rose upward a foot in the air, asif it were made of paper.
"My word!" exclaimed Mr. Giddings, letting the craft back upon itswheels. "Who would have thought such a thing? I had faith in thisprinciple of the hollow wings and helium-gas, boys, but I never thoughtit could reduce the normal weight of the plane to such a vast extent,It is truly a wonderful idea."
"You might not believe it, but the Sky-Bird weighs less than twohundred pounds as she stands," said Paul. "Just before you came today,Mr. Giddings, Bob and I, one at each end, easily lifted her clear offthe floor."
"It's what we aimed for, and we've got it," added John withsatisfaction, while Tom Meeks nodded his head and ejaculated, "I'd sayso! I'd say so!" his whole broad face abeam. "This feather lightnessmeans great lift, great speed, and great cruising range."
"I should think so surely," was the decided response of the newspaperman. "I notice you have installed that 'automatic pilot' too. Andwhat's that up here in front on top of the cabin? A searchlight, as Ilive!"
"Yes, dad," said Bob; "we thought that would be a good thing in case wedo any night traveling on this tour of the world. It ought to havegood power, being operated with current from the storage batteries ofthe wireless wind-dynamo."
After a little more inspection and further questions, Mr. Giddings tookhis departure, promising to be on hand at the hangar the followingmorning for the test flight.