A NEW IDEA IN AEROPLANES
As Andy Leighton prepared for bed that night, one idea possessed his
mind. He would in some manner penetrate Ba’s ignorance and learn the
story of Timbado Key and its king.
Then he fell asleep to dream of a tropic isle whereon, beneath palms, a
band of ghoulish savages, black, and clad in skins and feathers, knelt
in groveling obeisance before a chief, their king, the cannibal Cajou.
His brain was yet full of these things in the morning, but the first
smell of the shavings in the shop was an antidote; Ba and Timbado, for
the moment, were put aside.
“Since I’ve got you started,” said Andy to the captain, after an hour
of replanning, “I guess I’ll go over to my own factory. I’m goin’ to
make the wooden part of the tail guide here, but I’ve got to do the
metal work, the cogwheels, shaft-guides, and lever joints on the forge
and lathe.”
This was Wednesday morning. Friday evening when the _Red Bird_
returned from the Leighton cottage, it carried a box of shaft cogs and
other metal parts. In the shop that evening, stood, in the rough, the
frame of the future car――Captain Anderson’s handiwork.
The spread of this frame was a little over thirty-six feet, and,
despite Andy’s fortunate find of spruce, the four horizontal beams were
of pine, each cleverly spliced in three places with one-quarter inch
stove bolts to a short, thinned under piece. But the stanchions holding
the two planes together, and the struts connecting and bracing the
front and back beams were of spruce, as were all the rib pieces. Pine
weighs as much as spruce, but it is only five-eighths as strong.
Captain Anderson, having acquainted himself thoroughly with the plans,
set about the actual work of construction in his own manner.
The four car beams were each 36 feet, 4 inches long. They were to be
the basis of a car 6 feet deep and 5 feet high. After two of the light,
slender beams had been laid on the floor, and the eight struts had been
laid across them, the latter were made fast to the beams by liberal
coats of glue and close winding with the waxed seine thread. The other
beams were treated in the same manner. This required a full day’s
time, and the big, fragile-looking frames were set aside to dry.
The next morning, Andy’s impatience to test the engine could be no
longer restrained.
“What’s the use of an aeroplane, if that don’t work?” he argued.
The engine responded slowly when started, stopped after a few
revolutions, and then fell to work with an exhaust of thick, black
smoke.
“What’s the trouble?” exclaimed the captain.
“No trouble,” answered the boy. “It’s only oil in the cylinders――it’ll
be out in a short time. She’s fine and dandy.”
With regret, Andy shut off the engine to help with the other work. The
task of connecting the upper and lower frames was then undertaken.
Sixteen stanchions had been rounded and sandpapered until the
wind-friction-corners had been removed. The ends of each of these had
been slightly slotted. They were then set upright between the upper and
lower frames, and, after being liberally painted with glue, screwed to
the beams opposite each stanchion end. The attached ends were carefully
wrapped with the seine thread, which was also glued, and another day’s
work was at an end.
“Kind o’ light and flimsy,” suggested the captain, when they finally
quit work.
“Sure,” admitted Andy. “It wouldn’t hold at all that way. It won’t be
rigid until we get the wire braces on. Then we’ll tune her up like a
fiddle. This string and glue don’t do much but hold the frame together
until we get the wires attached. They’ll brace her like a bridge span.”
The sawing of the spruce strips for ribs――pieces 6 feet long by ¾ inch
thick and an inch wide――was the program for the next day. Captain
Anderson adjusted the small power circular saw that was a part of his
outfit, and the roughing of the slender pieces was soon accomplished.
As each had to be delicately planed, sandpapered, and shellacked, this
job ran into night again.
That evening, Mrs. Leighton began to wonder if she might not get a
letter from her husband the next day in relation to the little estate
and its disposition.
“I hope not,” whispered Andy to his friend, the captain. “He’ll likely
put a crimp in my airship plans.”
“Put a crimp in _your_ airship plans?” repeated Captain Anderson
soberly. “What have you got to do with the airship? Aren’t you working
for me? It’s your father and I who are partners.”
“Oh, of course,” replied the boy. “Of course――I forgot. But he may not
want me to work on it.”
“That needn’t stop the work,” exclaimed the captain. “I think I’ll
go ahead just the same. I reckon I’ve got a sort of interest in the
engine, and, as for the bird-tail rudder, I can give that up if he
wants it. But he won’t; he’s a mechanic.”
The letter did not come the next day, but when it did, in the middle of
the following week, it was even enthusiastic about the possibilities of
the discovered model, and congratulated Mrs. Leighton on her good luck
in being able to make an arrangement with Captain Anderson to work out
the idea. It said nothing about Andy’s work on the testing apparatus.
This was probably because of Mr. Leighton’s special interest in his
wife’s description of her brother’s estate. How much this was, was
indicated by his suggestion that no part of the property be sold, as he
was arranging, if possible, to come to Florida in about two weeks.
When Mrs. Leighton read this, Andy did not “hurrah.” Instead, he made
a quick calculation. Then he smiled. In two weeks the aeroplane would
be completed, and _someone_ would have tested it.
There were over eighty ribs to be attached to the two frames of the
aeroplane. At intervals of about a foot, the front end of each strip
was screwed to the top of the forward beam. Extending the strip back
over the rear beam, it was made fast there with screws. Two feet of
the free end of each strip extended beyond the rear beam. These having
been put in place, there was a hasty smoothing of all timbers with
sandpaper and another coat of shellac and when Saturday night came, the
big skeleton-like, fragile-looking frame, which almost filled the big
boatshed, was locked up with the feeling that the hardest work had been
accomplished.
By Tuesday night, both planes had been covered. The muslin, cut in full
six-foot pieces, had been soaked in Andy’s waterproof solution (equal
parts of alum and sugar of lead) and dried. Then one end of a piece was
glued to the front edge of the beam and fastened with copper tacks.
Carefully the strip was drawn back, and, as it was stretched skin
tight, made fast with small tacks to the ribs. The rear end was turned
under and glued to prevent raveling.
“This is worse than ribbin’ her,” panted Andy more than once as he
pulled at the muslin. “And I reckon the bottom ain’t agoin’ to be any
easier.”
Nor was it. But when the work was done, the result of a week’s labor
began to look like an aeroplane. The muslin was now treated to a good
coat of varnish, which turned the white stretches to a golden brown
color.
The next step was the bracing of the frame with wires. Suitable metal
plates, with hooks, to be attached to the stanchions to afford points
for holding the wires, were not available. Therefore, these were made
out of sheet steel by Andy and Captain Anderson in the shop over on
Goat Creek. Screw holes were bored by the hand drill found there, and
an edge of each sheet was turned into a hook by heating the metal in
the forge and blue-tempering the plate afterwards.
Progress seemed to be slower now, but the interest in the work
increased in proportion. When all the open spaces between the
stanchions had been crossed with diagonal wires tied to the steel
plates at the top and bottom of each upright and the turn-buckles
had been inserted in the middle of each length of wire, the proud
artificers were ready to key the unstable frame into rigidity.
This was a most delicate task. Truing the long frame on the floor and
squaring its vertical parts with a level, the task was to tighten the
wires without warping the sections.
“It’s like tunin’ a piano,” laughed Andy.
“Or tightenin’ a sawbuck,” suggested the captain.
Then Andy discovered that the tightened, straining wires were acutely
vibrant, and he began to test his work by twanging the wires with his
fingers, like the strings of a harp.
“Here, you,” exclaimed the busy boat builder, “you can’t work and play,
too――”
“You can’t?” laughed Andy. “What are you doin’?”
“I guess you’re right,” snickered Captain Anderson. “The whole thing is
play to me.”
A part of nearly every evening of the ten days already consumed in
making the aeroplane frame had been devoted to theories and sketches
and plans for attaching the bird-tail rudder, the engine and propeller
shafts, the wires to flex the free extensions of the upper plane and,
most important of all, a universal lever to flex the planes and operate
the tail rudder simultaneously.
Pieces and braces were now attached to the frame to hold the engine and
propellers similar to those on the Wright machine. The seat for the
operator also followed the Wright plan. The universal operating lever
was an ingenious adaptation of the Wright control.
“It looks good to me,” approved Andy, when the resourceful captain
suggested the contrivance.
“It’s about as flimsy as everything else,” grunted Captain Anderson.
“I’d hate to trust my safety to this, or any other part of the spidery
thing――”
“Hush!” interrupted the boy, with a warning finger. “Not a word o’ that
kind where mother can hear it. Now, when I get up in that thing――”
“You?” broke in the captain, looking very sober, as he did when much
amused. “Who said you were going up in it?”
“Pshaw!” retorted the boy, “you know _you_ ain’t. And Ba ain’t――”
“Don’t fly your aeroplane till it’s built,” teased the captain.
The lever to operate the planes and bird-tail rudder was at the right
of the operator’s seat. It was to be attached to the forward beam by
means of a rocking-hinge――also devised by Captain Anderson, and later
made by Andy――that permitted a straight motion forward and back and a
movement to right and left at right angles to the other motion.
About six inches above the beam, a wire was made fast to the lever.
This wire extended to the right and left, and passed beneath grooved
wheels attached to the base of the first and second stanchions to the
right and left. From the second wheel on each side the wire passed up
and diagonally to the rear and far corner of the upper plane, where
it was made fast. Throwing the lever to the right drew down the rear
of the extended upper plane on the left, while the contrary motion
reversed the operation.
A frame of spruce and pine, extending ten feet in the rear, passing
between the orbits of the propellers and braced with wires extending
to the ends of the car beams, was planned to carry the proposed
tail-guide. The shaft to operate this was a reinforced length of spruce.
This rudder shaft extended to the universal control lever. From this
end of the shaft, a quarter-inch round steel pin extended through the
lever and was secured by a nut so that the shaft might revolve and yet
be pushed backward and forward by a front and rear movement of the
control rudder.
The mechanism to revolve the shaft to the right or left at the same
time was what taxed Captain Anderson. In an attempt to secure this
result, he added a small hand lever to the top of the principal control
lever. This adjunct was so hinged that it might be moved only to the
right and left, and had no play forward or backward. At the base of
this little lateral lever a cross-arm was attached, about six inches
long. The movement of the little lever gave this cross-arm a rocking
motion up and down.
From each end of the rocking lever a hinged arm extended downward and
engaged――through guides――a cogged wheel, also fastened on the control
shaft.
“I’ll bet that’s exactly the way my uncle meant it to work,” commented
Andy enthusiastically. “If you throw the control lever to the right,
the left rear plane is depressed. The same motion turns the wheel on
the lever shaft. This, working in the cog on the rudder shaft, gives it
a reverse motion――and that throws the fins of the tail on a diagonal
slant to the right.”
“I’m followin’ out your idea,” assented the captain. “But I don’t know
what it means.”
Andy laughed and explained it all again.
“Turning to the right with the usual rudder, tends to make the machine
dart in that direction, just as a boat does when you turn quickly.
To stop that, a part of the aeroplane surface on that side is drawn
down――that increases the atmospheric pressure and tends to right the
machine; the flexing wires see to that. But my uncle’s bird-tail guide
goes further: it attempts to lessen this tendency to dart by flexing
the rudder on the side that isn’t doing the turning. By elevating the
idle corner, he decreases the wind pressure, and that part of the
machine settles. See?”
“I don’t,” admitted the captain. “But there’s the machinery to do what
you want.”