TOM SWIFT AND HIS AERIAL WARSHIP
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Victor Appleton >> TOM SWIFT AND HIS AERIAL WARSHIP
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Tom called for some of his men to take charge of the steering
and running of the Mars while he and Lieutenant Marbury prepared
to fire the two larger weapons. This was to be one of the most
important tests.
Service charges had been put in, though, of course, no
projectiles would be used, since they were then flying over a
large city not far from Shopton.
"We'll have to wait until we get out over the ocean to give a
complete test, with a bursting shell," Tom said.
He and Lieutenant Marbury were beside a gun, and were about to
fire it, when suddenly, from the stern of the ship, came a
ripping, tearing sound, and, at the same time, confused shouts
came from the crew's quarters.
"What is it?" cried Tom.
"One of the propellers!" was the answer. "It's split, and has
torn a big hole in the gas bag!"
"Bless my overshoes!" cried Mr. Damon. "We're going down!"
All on board the Mars became aware of a sudden sinking
sensation.
CHAPTER XVI
TOM IS WORRIED
"Steady, all!" came in even tones from Tom Swift. Not for an instant
had he lost his composure. For it was an accident, that much was certain,
and one that might endanger the lives of all on board.
Above the noise of the machinery in the motor room could be
heard the thrashing and banging of the broken or loose propeller-
blade. Just what its condition was, could not be told, as a bulge
of the gas bag hid it from the view of those gathered about the
gun, which was about to be fired when the alarm was given.
"We're sinking!" cried Mr. Damon. "We're going down, Tom!"
"That's nothing," was the cool answer. "It is only for a
moment. Only a few of the gas compartments can be torn. There
will soon enough additional gas in the others to lift us again."
And so it proved. The moment the pressure of the lifting gas in
the big oiled silk and aluminum container was lowered, it started
the generating machine, and enough extra gas was pumped into the
uninjured compartments to compensate for the loss.
"We're not falling so fast now," observed Ned.
"No, and we'll soon stop falling altogether," calmly declared
Tom. "Too bad this accident had to happen, though."
"It might have been much worse, my boy!" exclaimed the
lieutenant. "That's a great arrangement of yours--the automatic
gas machine."
"It's on the same principle as the air brakes of a trolley
car," explained Tom, when a look at the indicators showed that
the Mars had ceased falling and remained stationary in the air.
Tom had also sent a signal to the engine-room to shut off the
power, so that the two undamaged propellers, as well as the
broken one, ceased revolving.
"In a trolley car, you see," Tom went on, when the excitement
had calmed down, "as soon as the air pressure in the tanks gets
below a certain point, caused by using the air for a number of
applications of the brakes, it lets a magnetized bar fall, and
this establishes an electrical connection, starting the air pump.
The pump forces more air into the tanks until the pressure is
enough to throw the pump switch out of connection, when the pump
stops. I use the same thing here."
"And very clever it is," said Mr. Damon. "Do you suppose the
danger is all over, Tom?"
"For the time being, yes. But we must unship that damaged
propeller, and go on with the two."
The necessary orders were given, and several men from the
engine-room at once began the removal of the damaged blades.
As several spare ones were carried aboard one could be put on
in place of the broken one, had this been desired. But Tom
thought the accident a good chance to see how his craft would act
with only two-thirds of her motive force available, so he did not
order the damaged propeller replaced. When it was lowered to the
deck it was carefully examined.
"What made it break?" Ned wanted to know.
"That's a question I can't answer," Tom replied. "There may
have been a defect in the wood, but I had it all carefully
examined before I used it."
The propeller was one of the "built-up" type, with alternate
layers of ash and mahogany, but some powerful force had torn and
twisted the blades. The wood was splintered and split, and some
jagged pieces, flying off at a tangent, so great was the
centrifugal force, had torn holes in the strong gas bag.
"Did something hit it; or did it hit something?" asked Ned as
he saw Tom carefully examining the broken blades.
"Hard to say. I'll have a good look at this when we get back.
Just now I want to finish that gun test we didn't get a chance to
start."
"You don't mean to say you're going to keep on, and with the
balloon damaged; are you?" cried Mr. Damon, in surprise.
"Certainly--why not?" Tom replied. "In warfare accidents may
happen, and if the Mars can't go on, after a little damage like
this, what is going to happen when she's fired on by a hostile
ship? Of course I'm going on!"
"Bless my necktie!" ejaculated the odd man.
"That's the way to talk!" exclaimed Lieutenant Marbury. "I'm
with you."
There really was very little danger in proceeding. The Mars was
just as buoyant as before, for more gas had been automatically
made, and forced into the uninjured compartments of the bag. At
the same time enough sand ballast had been allowed to run out to
make the weight to be lifted less in proportion to the power
remaining.
True, the speed would be less, with two propellers instead of
three, and the craft would not steer as well, with the torn ends
of the gas bag floating out behind. But this made a nearer
approach to war conditions, and Tom was always glad to give his
inventions the most severe tests possible.
So, after a little while, during which it was seen that the
Mars was proceeding almost normally, the matter of discharging
the guns was taken up again.
The weapons were all ready to fire, and when Tom had attached
the pressure gauges to note how much energy was expended in the
recoil, he gave the word to fire.
The two big weapons were discharged together, and for a moment
after the report echoed out among the cloud masses every soul on
the ship feared another accident had happened.
For the big craft rolled and twisted, and seemed about to turn
turtle. Her forward progress was halted, momentarily, and a cry
of fear came from several of the members of the crew, who had had
only a little experience in aircraft.
"What's the matter?" cried Ned. "Something go wrong?"
"A little," admitted Tom, with a rueful look on his face.
"Those recoil checks didn't work as well in practice as they did
in theory."
"Are you sure they are strong enough?" asked Lieutenant
Marbury.
"I thought so," spoke Tom. "I'll put more tension on the spring
next time."
"Bless my watch chain!" cried Mr. Damon. "You aren't going to
fire those guns again; are you, Tom?"
"Why not? We can't tell what's the matter, nor get things
right without experimenting. There's no danger."
"No danger! Don't you call nearly upsetting the ship danger?"
"Oh, well, if she turns over she'll right herself again," Tom
said. "The center of gravity is low, you see. She can't float in
any position but right side up, though she may turn over once or
twice."
"Excuse me!" said Mr. Damon firmly. "I'd rather go down, if
it's all the same to you. If my wife ever knew I was here I'd
never hear the last of it!"
"We'll go down soon," Tom promised. "But I must fire a couple
of shots more. You wouldn't call the recoil checks a success,
would you?" and the young inventor appealed to the government
inspector.
"No, I certainly would not," was the prompt answer. "I am
sorry, too, for they seemed to be just what was needed. Of course
I understand this is not an official test, and I am not obliged
to make a report of this trial. But had it been, I should have
had to score against you.
"I realize that, and I'm not asking any favors. but I'll try it
again with the recoil checks tightened up. I think the
hydrostatic valves were open too much, also."
Preparations were now made for firing the four-inch guns once
more. All this while the Mars had been speeding around in space,
being about two miles up in the air. Tom's craft was not designed
to reach as great an elevation as would be possible in an
aeroplane, since to work havoc to an enemy's fortifications by
means of aerial bombs they do not need to be dropped from a great
height.
In fact, experiments in Germany have shown that bombs falling
from a great height are less effective than those falling from an
airship nearer the earth. For a bomb, falling from a height of
two miles, acquires enough momentum to penetrate far into the
earth, so that much of the resultant explosive force is expended
in a downward direction, and little damage is done to the
fortifications. A bomb dropped from a lower altitude, expending
its force on all sides, does much more damage.
On the other hand, in destroying buildings, it has been found
desirable to drop a bomb from a good height so that it may
penetrate even a protected roof, and explode inside.
Once more Tom made ready to fire, this time having given the
recoil checks greater resistance. But though there was less
motion imparted to the airship when the guns were discharged,
there was still too much for comfort, or even safety.
"Well, something's wrong, that's sure," remarked Tom, in rather
disappointed tones as he noted the effect of the second shots.
"If we get as much recoil from the two guns, what would happen if
we fired them all at once?"
"Don't do it! Don't do it, I beg of you!" entreated Mr. Damon.
"Bless my toothbrush--don't do it!"
"I won't--just at present," Tom said, ruefully. "I'm afraid
I'll have to begin all over again, and proceed along new lines."
"Well, perhaps you will," said the lieutenant. "But you may
invent something much better than anything you have now. There is
no great rush. Take your time, and do something good."
"Oh, I'll get busy on it right away," Tom declared. "We'll go
down now, and start right to work. I'm afraid, Ned, that our idea
of a door-spring check isn't going to work."
"I might have known my idea wouldn't amount to anything," said
the young bank clerk.
"Oh, the idea is all right," declared Tom, "but it wants
modifying. There is more power to those recoils than I figured,
though our first experiments seemed to warrant us in believing
that we had solved the problem."
"Are you going to try the bomb-dropping device?" asked the
lieutenant.
"Yes, there can't be any recoil from that," Tom said. "I'll
drop a few blank ones, and see how accurate the range finders
are."
While his men were getting ready for this test Tom bent over
the broken propeller, looking from that to the recoil checks,
which had not come up to expectations. Then he shook his head in
a worried and puzzled manner.
CHAPTER XVII
AN OCEAN FLIGHT
Dropping bombs from an aeroplane, or a dirigible balloon, is a
comparatively simple matter. Of course there are complications
that may ensue, from the danger of carrying high explosives in
the limited quarters of an airship, with its inflammable gasoline
fuel, and ever-present electric spark, to the possible premature
explosion of the bomb itself. But they seem to be considered
minor details now.
On the other hand, while it is comparatively easy to drop a
bomb from a moving aeroplane, or dirigible balloon, it is another
matter to make the bomb fall just where it will do the most
damage to the enemy. It is not easy to gauge distances, high up
in the air, and then, too, allowance must be made for the speed
of the aircraft, the ever-increasing velocity of a falling body,
and the deflection caused by air currents.
The law of velocity governing falling bodies is well known. It
varies, of course, according to the height, but in general a body
falling freely toward the earth, as all high-school boys know, is
accelerated at the rate of thirty-two feet per second. This law
has been taken advantage of by the French in the present European
war. The French drop from balloons, or aeroplanes, a steel dart
about the size of a lead pencil, and sharpened in about the same
manner. Dropping from a height of a mile or so, that dart will
acquire enough velocity to penetrate a man from his head all the
way through his body to his feet.
But in dropping bombs from an airship the damage intended does
not so much depend on velocity. It is necessary to know how fast
the bomb falls in order to know when to set the time fuse that
will explode it; though some bombs will explode on concussion.
At aeroplane meets there are often bomb-dropping contests, and
balls filled with a white powder (that will make a dust-cloud on
falling, and so show where they strike) are used to demonstrate
the birdman's accuracy.
"We'll see how our bomb-release works," Tom went on. "But we'll
have to descend a bit in order to watch the effect."
"You're not going to use real bombs, are you, Tom?" asked Ned.
"Indeed not. Just chalk-dust ones for practice. Now here is
where the bombs will be placed," and he pointed to the three
openings in the floor of the amidship cabin. The wire nettings
were taken out and one could look down through the holes to the
earth below, the ground being nearer now, as Tom had let out some
of the lifting gas.
"Here is the range-finder and the speed calculator," the young
inventor went on as he indicated the various instruments. "The
operator sits here, where he can tell when is the most favorable
moment for releasing the bomb."
Tom took his place before a complicated set of instruments, and
began manipulating them. One of his assistants, under the
direction of Lieutenant Marbury, placed in the three openings
bombs, made of light cardboard, just the size of a regular bomb,
but filled with a white powder that would, on breaking, make a
dust-cloud which could be observed from the airship.
"I have first to determine where I want to drop the bomb," Tom
explained, "and then I have to get my distance from it on the
range-finder. Next I have to know how fast I am traveling, and
how far up in the air I am, to tell what the velocity of the
falling bomb will attain at a certain time. This I can do by
means of these instruments, some of which I have adapted from
those used by the government," he said, with a nod to the
officer.
"That's right--take all the information you can get," was the
smiling response.
"We will now assume that the bombs are in place in the holes in
the floor of the cabin," Tom went on. "As I sit here I have
before me three buttons. They control the magnets that hold the
bombs in place. If I press one of the buttons it breaks the
electrical current, the magnet no longer has any attraction, and
it releases the explosive. Now look down. I am going to try and
drop a chalk bomb near that stone fence."
The Mars was then flying over a large field and a stone fence
was in plain view.
"Here she goes!" cried Tom, as he made some rapid calculations
from his gauge instruments. There was a little click and the
chalk bomb dropped. There was a plate glass floor in part of the
cabin, and through this the progress of the pasteboard bomb could
be observed.
"She'll never go anywhere near the fence!" declared Ned. "You
let it drop too soon, Tom!"
"Did I? You just watch. I had to allow for the momentum that
would be given the bomb by the forward motion of the balloon."
Hardly had Tom spoken than a puff of white was seen on the very
top of the fence.
"There it goes?" cried the lieutenant. "You did the trick,
Swift!"
"Yes, I thought I would. Well, that shows my gauges are
correct, anyhow. Now we'll try the other two bombs."
In succession they were released from the bottom of the cabin,
at other designated objects. The second one was near a tree. It
struck within five feet, which was considered good.
"And I'll let the last one down near that scarecrow in the
field," said Tom, pointing to a ragged figure in the middle of a
patch of corn.
Down went the cardboard bomb, and so good was the aim of the
young inventor that the white dust arose in a cloud directly back
of the scarecrow.
And then a queer thing happened. For the figure seemed to come
to life, and Ned, who was watching through a telescope, saw a
very much excited farmer looking up with an expression of the
greatest wonder on his face. He saw the balloon over his head,
and shook his fist at it, evidently thinking he had had a narrow
escape. But the pasteboard bomb was so light that, had it hit
him, he would not have been injured, though he might have been
well dusted.
"Why, that was a man! Bless my pocketbook!" cried Mr. Damon.
"I guess it was," agreed Tom. "I took it for a scarecrow."
"Well, it proved the accuracy of your aim, at any rate,"
observed Lieutenant Marbury. "The bomb dropping device of your
aerial warship is perfect--I can testify to that."
"And I'll have the guns fixed soon, so there will be no danger
of a recoil, too," added Tom Swift, with a determined look on his
face.
"What's next?" asked Mr. Damon, looking at his watch. "I really
ought to be home, Tom."
"We're going back now, and down. Are you sure you don't want me
to drop you in your own front yard, or even on your roof? I think
I could manage that."
"Bless my stovepipe, no, Tom! My wife would have hysterics.
Just land me at Shopton and I'll take a car home."
The damaged airship seemed little the worse for the test to
which she had been subjected, and made her way at good speed in
the direction of Tom's home. Several little experiments were
tried on the way back. They all worked well, and the only two
problems Tom had to solve were the taking care of the recoil from
the guns and finding out why the propeller had broken.
A safe landing was made, and the Mars once more put away in her
hangar. Mr. Damon departed for his home, and Lieutenant Marbury
again took up his residence in the Swift household.
"Well, Tom, how did it go?" asked his father.
"Not so very well. Too much recoil from the guns."
"I was afraid so. You had better drop this line of work, and go
at something else."
"No, Dad!" Tom cried. "I'm going to make this work. I never had
anything stump me yet, and I'm not going to begin now!"
"Well, that's a good spirit to show," said the aged inventor,
with a shake of his head, "but I don't believe you'll succeed,
Tom."
"Yes I will, Dad! You just wait."
Tom decided to begin on the problem of the propeller first, as
that seemed more simple. He knew that the gun question would take
longer.
"Just what are you trying to find out, Tom?" asked Ned, a few
nights later, when he found his chum looking at the broken parts
of the propeller.
"Trying to discover what made this blade break up and splinter
that way. It couldn't have been centrifugal force, for it wasn't
strong enough."
Tom was "poking" away amid splinters, and bits of broken wood,
when he suddenly uttered an exclamation, and held up something.
"Look!" he cried. "I believe I've found it."
"What?" asked Ned.
"The thing that weakened the propeller. Look at this, and
smell!" He held out a piece of wood toward Ned. The bank employee
saw where a half-round hole had been bored in what remained of
the blade, and from that hole came a peculiar odor.
"It's some kind of acid," ventured Ned.
"That's it!" cried Tom. "Someone bored a hole in the propeller,
and put in some sort of receptacle, or capsule, containing a
corrosive acid. In due time, which happened to be when we took
our first flight, the acid ate through whatever it was contained
in, and then attacked the wood of the propeller blade. It
weakened the wood so that the force used in whirling it around
broke it."
"Are you sure of that?" asked Ned.
"As sure as I am that I'm here! Now I know what caused the
accident!"
"But who would play such a trick?" asked Ned. "We might all
have been killed."
"Yes, I know we might," said Tom. "It must be the work of some
of those foreign spies whose first plot we nipped in the bud. I
must tell Marbury of this, but don't mention it to dad."
"I won't," promised Ned.
Lieutenant Marbury agreed with Tom that someone had
surreptitiously bored a small hole in the propeller blade, and
had inserted a corrosive acid that would take many hours to
operate. The hole had been varnished over, probably, so it would
not show.
"And that means I've got to examine the other two blades," Tom
said. "They may be doctored too."
But they did not prove to be. A careful examination showed
nothing wrong. An effort was made to find out who had tried to
destroy the Mars in midair, but it came to nothing. The two men
in custody declared they knew nothing of it, and there was no way
of proving that they did.
Meanwhile, the torn gas bag was repaired, and Tom began working
on the problem of doing away with the gun recoil. He tried
several schemes, and almost was on the point of giving up when
suddenly he received a hint by reading an account of how the
recoil was taken care of on some of the German Zeppelins.
The guns there were made double, with the extra barrel filled
with water or sand, that could be shot out as was the regular
charge. As both barrels were fired at the same time, and in
opposite directions, with the same amount of powder, one
neutralized the other, and the recoil was canceled, the ship
remaining steady after fire.
"By Jove! I believe that will do the trick!" cried Tom. "I'm
going to try it."
"Good luck to you!" cried Ned.
It was no easy matter to change all the guns of the Mars, and
fit them with double barrels. But by working day and night shifts
Tom managed it. Meanwhile, a careful watch was kept over the
shops. Several new men applied for work, and some of them were
suspicious enough in looks, but Tom took on no new hands.
Finally the new guns were made, and tried with the Mars held on
the ground. They behaved perfectly, the shooting of sand or water
from the dummy barrel neutralizing the shot from the service
barrel.
"And now to see how it works in practice!" cried Tom one day.
"Are you with me for a long flight, Ned?"
"I sure am!"
The next evening the Mars, with a larger crew than before, and
with Tom, Ned, Mr. Damon and Lieutenant Marbury aboard, set
sail.
"But why start at night?" asked Ned.
"You'll see in the morning," Tom answered.
The Mars flew slowly all night, life aboard her, at about the
level of the clouds, going on almost as naturally as though the
occupants of the cabins were on the earth. Excellent meals were
served.
"But when are you going to try the guns?" asked Ned, as he got
ready to turn in.
"Tell you in the morning," replied Tom, with a smile.
And, in the morning, when Ned looked down through the plate
glass in the cabin floor, he uttered a cry.
"Why, Tom! We're over the ocean!" he cried.
"I rather thought we'd be," was the calm reply. "I told George
to head straight for the Atlantic. Now we'll have a test with
service charges and projectiles!"
CHAPTER XVIII
IN A STORM
Surprise, for the moment, held Mr. Damon, Ned and Lieutenant
Marbury speechless. They looked from the heaving waters of the
ocean below them to the young pilot of the Mars. He smiled at
their astonishment.
"What--what does it mean, Tom?" asked Ned. "You never said you
were going to take a trip as far as this."
"That's right," chimed in Mr. Damon. "Bless my nightcap! If I
had known I was going to be brought so far away from home I'd
never have come."
"You're not so very far from Water ford," put in Tom. "We
didn't make any kind of speed coming from Shopton, and we could
be back again inside of four hours if we had to."
"Then you didn't travel fast during the night?" asked the
government man.
"No, we just drifted along," Tom answered. "I gave orders to
run the machinery slowly, as I wanted to get it in good shape for
the other tests that will come soon. But I told George, whom I
left in charge when I turned in, to head for New York. I wanted
to get out over the ocean to try the guns with the new recoil
arrangement."
"Well, we're over the ocean all right," spoke Ned, as he looked
down at the heaving waters.
"It isn't the first time," replied Tom cheerfully. "Koku, you
may serve breakfast now," for the giant had been taken along as a
sort of cook and waiter. Koku manifested no surprise or alarm
when he found the airship floating over the sea. Whatever Tom did
was right to him. He had great confidence in his master.
"No, it isn't the first time we've taken a water flight," spoke
Ned. "I was only surprised at the suddenness of it, that's all."
"It's my first experience so far out above the water," observed
Lieutenant Marbury, "though of course I've sailed on many seas.
Why, we're out of sight of land."
"About ten miles out, yes," admitted Tom. "Far enough to make
it safe to test the guns with real projectiles. That is what I
want to do."
"And we've been running all night?" asked Mr. Damon.
"Yes, but at slow speed. The engines are in better shape now
than ever before," Tom said. "Well, if you're ready we'll have
breakfast."
The meal was served by Koku with as much unconcern as though
they were in the Swift homestead back in Shopton, instead of
floating near the clouds. And while it was being eaten in the
main cabin, and while the crew was having breakfast in their
quarters, the aerial warship was moving along over the ocean in
charge of George Watson, one of Tom's engineers, who was
stationed in the forward pilot-house.
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