Construction and Operation
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Unknown >> Construction and Operation
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Preserving Longitudinal Balance.
"The birds maintain longitudinal, or fore and aft balance,
by elevating or depressing their tails. Whether
this action is secured in an aeroplane by means of a
horizontal rudder placed in the rear, or by deflecting
planes placed in front of the main planes, the principle
is evidently the same. A horizontal rudder placed well
to the rear as in the Antoinette, Bleriot or Santos-Dumont
monoplanes, will be very much safer and steadier
than the deflecting planes in front, as in the Wright or
Curtiss biplanes, but not so sensitive or prompt in action.
"The natural fore and aft stability is very much
strengthened by placing the load well forward. The
center of gravity near the front and a tail or rudder
streaming to the rear secures stability as an arrow is
balanced by the head and feathering. The adoption of
this principle makes it almost impossible for the aeroplane
to turn over.
The Matter of Lateral Balance.
"All successful aeroplanes thus far have maintained
lateral balance by the principle of changing the angle
of incidence of the wings.
"Other ways of maintaining the lateral balance, suggested
by observation of the flight of birds are--extending
the wing tips and spilling the air through the pinions;
or, what is the same thing, varying the area of the
wings at their extremities.
"Extending the wing tips seems to be a simple and
effective solution of the problem. The tips may be made
to swing outward upon a vertical axis placed at the front
edge of the main planes; or they may be hinged to the
ends of the main plane so as to be elevated or depressed
through suitable connections by the aviator; or they may
be supported from a horizontal axis parallel with the
ends of the main planes so that they may swing outward,
the aviator controlling both tips through one lever
so that as one tip is extended the other is retracted.
"The elastic wing pinions of a bird bend easily before
the wind, permitting the gusts to glance off, but presenting
always an even and efficient curvature to the
steady currents of the air."
High Winds Threaten Stability.
To ensure perfect stability, without control, either human
or automatic, it is asserted that the aeroplane must
move faster than the wind is blowing. So long as the
wind is blowing at the rate of 30 miles an hour, and the
machine is traveling 40 or more, there will be little trouble
as regards equilibrium so far as wind disturbance
goes, provided the wind blows evenly and does not come
in gusts or eddying currents. But when conditions are
reversed--when the machine travels only 30 miles an
hour and the wind blows at the rate of 50, look out for
loss of equilibrium.
One of the main reasons for this is that high winds
are rarely steady; they seldom blow for any length of
time at the same speed. They are usually "gusty," the
gusts being a momentary movement at a higher speed.
Tornadic gusts are also formed by the meeting of two
opposing currents, causing a whirling motion, which
makes stability uncertain. Besides, it is not unusual
for wind of high speed to suddenly change its direction
without warning.
Trouble With Vertical Columns.
Vertical currents--columns of ascending air--are
frequently encountered in unexpected places and have more
or less tendency, according to their strength, to make
it difficult to keep the machine within a reasonable
distance from the ground.
These vertical currents are most generally noticeable
in the vicinity of steep cliffs, or deep ravines. In such
instances they are usually of considerable strength, being
caused by the deflection of strong winds blowing
against the face of the cliffs. This deflection exerts a
back pressure which is felt quite a distance away from
the point of origin, so that the vertical current exerts an
influence in forcing the machine upward long before the
cliff is reached.
CHAPTER XV.
THE ELEMENT OF DANGER.
That there is an element of danger in aviation is
undeniable, but it is nowhere so great as the public
imagines. Men are killed and injured in the operation
of flying machines just as they are killed and injured in
the operation of railways. Considering the character of
aviation the percentage of casualties is surprisingly
small.
This is because the results following a collapse in the
air are very much different from what might be imagined.
Instead of dropping to the ground like a bullet an
aeroplane, under ordinary conditions will, when anything
goes wrong, sail gently downward like a parachute,
particularly if the operator is cool-headed and nervy enough
to so manipulate the apparatus as to preserve its equilibrium
and keep the machine on an even keel.
Two Fields of Safety.
At least one prominent aviator has declared that there
are two fields of safety--one close to the ground, and
the other well up in the air. In the first-named the fall
will be a slight one with little chance of the operator
being seriously hurt. From the field of high altitude the
the descent will be gradual, as a rule, the planes of the
machine serving to break the force of the fall. With a
cool-headed operator in control the aeroplane may be
even guided at an angle (about 1 to 8) in its descent so
as to touch the ground with a gliding motion and with
a minimum of impact.
Such an experience, of course, is far from pleasant,
but it is by no means so dangerous as might appear.
There is more real danger in falling from an elevation
of 75 or 100 feet than there is from 1,000 feet, as in the
former case there is no chance for the machine to serve as
a parachute--its contact with the ground comes too
quickly.
Lesson in Recent Accidents.
Among the more recent fatalities in aviation are the
deaths of Antonio Fernandez and Leon Delagrange. The
former was thrown to the ground by a sudden stoppage
of his motor, the entire machine seeming to collapse.
It is evident there were radical defects, not only in the
motor, but in the aeroplane framework as well. At the
time of the stoppage it is estimated that Fernandez was
up about 1,500 feet, but the machine got no opportunity
to exert a parachute effect, as it broke up immediately.
This would indicate a fatal weakness in the structure
which, under proper testing, could probably have been
detected before it was used in flight.
It is hard to say it, but Delagrange appears to have
been culpable to great degree in overloading his machine
with a motor equipment much heavier than it was
designed to sustain. He was 65 feet up in the air when
the collapse occurred, resulting in his death. As in the
case of Fernandez common-sense precaution would
doubtless have prevented the fatality.
Aviation Not Extra Hazardous.
All told there have been, up to the time of this writing
(April, 1910), just five fatalities in the history of power-
driven aviation. This is surprisingly low when the nature
of the experiments, and the fact that most of the
operators were far from having extended experience, is
taken into consideration. Men like the Wrights, Curtiss,
Bleriot, Farman, Paulhan and others, are now experts,
but there was a time, and it was not long ago, when they
were unskilled. That they, with numerous others less
widely known, should have come safely through their
many experiments would seem to disprove the prevailing
idea that aviation is an extra hazardous pursuit.
In the hands of careful, quick-witted, nervy men the
sailing of an airship should be no more hazardous than
the sailing of a yacht. A vessel captain with common
sense will not go to sea in a storm, or navigate a weak,
unseaworthy craft. Neither should an aviator attempt
to sail when the wind is high and gusty, nor with a machine
which has not been thoroughly tested and found to
be strong and safe.
Safer Than Railroading.
Statistics show that some 12,000 people are killed and
72,000 injured every year on the railroads of the United
States. Come to think it over it is small wonder that
the list of fatalities is so large. Trains are run at high
speeds, dashing over crossings at which collisions are
liable to occur, and over bridges which often collapse
or are swept away by floods. Still, while the number of
casualties is large, the actual percentage is small considering
the immense number of people involved.
It is so in aviation. The number of casualties is remarkably
small in comparison with the number of flights
made. In the hands of competent men the sailing of an
airship should be, and is, freer from risk of accident than
the running of a railway train. There are no rails to
spread or break, no bridges to collapse, no crossings at
which collisions may occur, no chance for some sleepy
or overworked employee to misunderstand the dispatcher's
orders and cause a wreck.
Two Main Causes of Trouble.
The two main causes of trouble in an airship leading
to disaster may be attributed to the stoppage of the
motor, and the aviator becoming rattled so that he loses
control of his machine. Modern ingenuity is fast developing
motors that almost daily become more and more
reliable, and experience is making aviators more and
more self-confident in their ability to act wisely and
promptly in cases of emergency. Besides this a satisfactory
system of automatic control is in a fair way
of being perfected.
Occasionally even the most experienced and competent
of men in all callings become careless and by foolish
action invite disaster. This is true of aviators the same
as it is of railroaders, men who work in dynamite mills,
etc. But in nearly every instance the responsibility rests
with the individual; not with the system. There are
some men unfitted by nature for aviation, just as there
are others unfitted to be railway engineers.
CHAPTER XVI.
RADICAL CHANGES BEING MADE.
Changes, many of them extremely radical in their nature,
are continually being made by prominent aviators,
and particularly those who have won the greatest amount
of success. Wonderful as the results have been few of
the aviators are really satisfied. Their successes have
merely spurred them on to new endeavors, the ultimate
end being the development of an absolutely perfect aircraft.
Among the men who have been thus experimenting
are the Wright Brothers, who last year (1909) brought
out a craft totally different as regards proportions and
weight from the one used the preceding year. One
marked result was a gain of about 3 1/2 miles an hour in
speed.
Dimensions of 1908 Machine.
The 1908 model aeroplane was 40 by 29 feet over all.
The carrying surfaces, that is, the two aerocurves, were
40 by 6 feet, having a parabolical curve of one in twelve.
With about 70 square feet of surface in the rudders, the
total surface given was about 550 square feet. The
engine, which is the invention of the Wright brothers,
weighed, approximately, 200 pounds, and gave about 25
horsepower at 1,400 revolutions per minute. The total
weight of the aeroplane, exclusive of passenger, but
inclusive of engine, was about 1,150 pounds. This result
showed a lift of a fraction over 2 1/4 pounds to the square
foot of carrying surface. The speed desired was 40
miles an hour, but the machine was found to make only
a scant 39 miles an hour. The upright struts were
about 7/8-inch thick, the skids, 2 1/2 by 1 1/4 inches thick.
Dimensions of 1909 Machine.
The 1909 aeroplane was built primarily for greater
speed, and relatively heavier; to be less at the mercy
of the wind. This result was obtained as follows: The
aerocurves, or carrying surfaces, were reduced in dimensions
from 40 by 6 feet to 36 by 5 1/2 feet, the curve
remaining the same, one in twelve. The upright struts
were cut from seven-eighths inch to five-eighths inch, and
the skids from two and one-half by one and one-quarter
to two and one-quarter by one and three-eighths inches.
This result shows that there were some 81 square feet
of carrying surface missing over that of last year's
model. and some 25 pounds loss of weight. Relatively,
though, the 1909 model aeroplane, while actually 25
pounds lighter, is really some 150 pounds heavier in the
air than the 1908 model, owing to the lesser square
feet of carrying surface.
Some of the Results Obtained.
Reducing the carrying surfaces from 6 to 5 1/2 feet
gave two results--first, less carrying capacity; and, second,
less head-on resistance, owing to the fact that the
extent of the parabolic curve in the carrying surfaces
was shortened. The "head-on" resistance is the retardance
the aeroplane meets in passing through the air,
and is counted in square feet. In the 1908 model the
curve being one in twelve and 6 feet deep, gave 6 inches
of head-on resistance. The plane being 40 feet spread,
gave 6 inches by 40 feet, or 20 square feet of head-on
resistance. Increasing this figure by a like amount for
each plane, and adding approximately 10 square feet for
struts, skids and wiring, we have a total of approximately,
50 square feet of surface for "head-on" resistance.
In the 1909 aeroplane, shortening the curve 6 inches
at the parabolic end of the curve took off 1 inch of
head-on resistance. Shortening the spread of the planes
took off between 3 and 4 square feet of head-on resistance.
Add to this the total of 7 square feet, less curve
surface and about 1 square foot, less wire and woodwork
resistance, and we have a grand total of, approximately,
12 square feet of less "head-on" resistance over
the 1908 model.
Changes in Engine Action.
The engine used in 1909 was the same one used in
1908, though some minor changes were made as
improvements; for instance, a make and break spark was
used, and a nine-tooth, instead of a ten-tooth magneto
gear-wheel was used. This increased the engine revolutions
per minute from 1,200 to 1,400, and the propeller
revolutions per minute from 350 to 371, giving a propeller
thrust of, approximately, 170 foot pounds instead
of 153, as was had last year.
More Speed and Same Capacity.
One unsatisfactory feature of the 1909 model over
that of 1908, apparently, was the lack of inherent lateral
stability. This was caused by the lesser surface and
lesser extent of curvatures at the portions of the
aeroplane which were warped. This defect did not show so
plainly after Mr. Orville Wright had become fully
proficient in the handling of the new machine, and with
skillful management, the 1909 model aeroplane will be
just as safe and secure as the other though it will take
a little more practice to get that same degree of skill.
To sum up: The aeroplane used in 1909 was 25
pounds lighter, but really about 150 pounds heavier in
the air, had less head-on resistance, and greater
propeller thrust. The speed was increased from about 39
miles per hour to 42 1/2 miles per hour. The lifting
capacity remained about the same, about 450 pounds
capacity passenger-weight, with the 1908 machine. In this
respect, the loss of carrying surface was compensated for
by the increased speed.
During the first few flights it was plainly demonstrated
that it would need the highest skill to properly
handle the aeroplane, as first one end and then the other
would dip and strike the ground, and either tear the canvas
or slew the aeroplane around and break a skid.
Wrights Adopt Wheeled Gears.
In still another important respect the Wrights, so far
as the output of one of their companies goes, have made
a radical change. All the aeroplanes turned out by the
Deutsch Wright Gesellschaft, according to the German
publication, _Automobil-Welt_, will hereafter be equipped
with wheeled running gears and tails. The plan of this
new machine is shown in the illustration on page 145.
The wheels are three in number, and are attached one
to each of the two skids, just under the front edge of
the planes, and one forward of these, attached to a cross-
member. It is asserted that with these wheels the
teaching of purchasers to operate the machines is much
simplified, as the beginners can make short flights on
their own account without using the starting derrick.
This is a big concession for the Wrights to make, as
they have hitherto adhered stoutly to the skid gear.
While it is true they do not control the German company
producing their aeroplanes, yet the nature of their
connection with the enterprise is such that it may be
taken for granted no radical changes in construction
would be made without their approval and consent.
Only Three Dangerous Rivals.
Official trials with the 1909 model smashed many records
and leave the Wright brothers with only three dangerous
rivals in the field, and with basic patents which
cover the curve, warp and wing-tip devices found on
all the other makes of aeroplanes. These three rivals
are the Curtiss and Voisin biplane type and the Bleriot
monoplane pattern.
The Bleriot monoplane is probably the most dangerous
rival, as this make of machine has a record of 54
miles per hour, has crossed the English channel, and
has lifted two passengers besides the operator. The latest type
of this machine only weighs 771.61 pounds complete,
without passengers, and will lift a total passenger
weight of 462.97 pounds, which is a lift of 5.21 pounds
to the square foot. This is a better result than those
published by the Wright brothers, the best noted being
4.25 pounds per square foot.
Other Aviators at Work.
The Wrights, however, are not alone in their efforts
to promote the efficiency of the flying machine. Other
competent inventive aviators, notably Curtiss, Voisin,
Bleriot and Farman, are close after them. The Wrights,
as stated, have a marked advantage in the possession of
patents covering surface plane devices which have thus
far been found indispensable in flying machine construction.
Numerous law suits growing out of alleged infringements
of these patents have been started, and
others are threatened. What effect these actions will
have in deterring aviators in general from proceeding
with their experiments remains to be seen.
In the meantime the four men named--Curtiss, Voisin,
Bleriot and Farman--are going ahead regardless of
consequences, and the inventive genius of each is so strong
that it is reasonable to expect some remarkable developments
in the near future.
Smallest of Flying Machines.
To Santos Dumont must be given the credit of producing
the smallest practical flying machine yet constructed.
True, he has done nothing remarkable with it
in the line of speed, but he has demonstrated the fact
that a large supporting surface is not an essential feature.
This machine is named "La Demoiselle." It is a monoplane
of the dihedral type, with a main plane on each
side of the center. These main planes are of 18 foot
spread, and nearly 6 1/2 feet in depth, giving approximately
115 feet of surface area. The total weight is 242 pounds,
which is 358 pounds less than any other machine which
has been successfully used. The total depth from front
to rear is 26 feet.
The framework is of bamboo, strengthened and held
taut with wire guys.
Have One Rule in Mind.
In this struggle for mastery in flying machine efficiency
all the contestants keep one rule in mind, and this
is:
"The carrying capacity of an aeroplane is governed
by the peripheral curve of its carrying surfaces, plus the
speed; and the speed is governed by the thrust of the
propellers, less the 'head-on' resistance."
Their ideas as to the proper means of approaching
the proposition may, and undoubtedly are, at variance,
but the one rule in solving the problem of obtaining the
greatest carrying capacity combined with the greatest
speed, obtains in all instances.
CHAPTER XVII.
SOME OF THE NEW DESIGNS.
Spurred on by the success attained by the more experienced
and better known aviators numerous inventors
of lesser fame are almost daily producing practical flying
machines varying radically in construction from
those now in general use.
One of these comparatively new designs is the Van
Anden biplane, made by Frank Van Anden of Islip,
Long Island, a member of the New York Aeronautic
Society. While his machine is wholly experimental,
many successful short flights were made with it last fall
(1909). One flight, made October 19th, 1909, is of particular
interest as showing the practicability of an automatic
stabilizing device installed by the inventor. The
machine was caught in a sudden severe gust of wind
and keeled over, but almost immediately righted itself,
thus demonstrating in a most satisfactory manner the
value of one new attachment.
Features of Van Anden Model.
In size the surfaces of the main biplane are 26 feet
in spread, and 4 feet in depth from front to rear. The
upper and lower planes are 4 feet apart. Silkolene
coated with varnish is used for the coverings. Ribs
(spruce) are curved one inch to the foot, the deepest
part of the curve (4 inches) being one foot back from the
front edge of the horizontal beam. Struts (also of
spruce, as is all the framework) are elliptical in shape.
The main beams are in three sections, nearly half round
in form, and joined by metal sleeves.
There is a two-surface horizontal rudder, 2x2x4 feet,
in front. This is pivoted at its lateral center 8 feet from
the front edge of the main planes. In the rear is another
two-surface horizontal rudder 2x2x2 1/2 feet, pivoted
in the same manner as the front one, 15 feet from the
rear edges of the main planes.
Hinged to the rear central strut of the rear rudder
is a vertical rudder 2 feet high by 3 feet in length.
The Method of Control.
In the operation of these rudders--both front and rear
--and the elevation and depression of the main planes,
the Curtiss system is employed. Pushing the steering-
wheel post outward depresses the front edges of the
planes, and brings the machine downward; pulling the
steering-wheel post inward elevates the front edges of
the planes and causes the machine to ascend.
Turning the steering wheel itself to the right swings
the tail rudder to the left, and the machine, obeying this
like a boat, turns in the same direction as the wheel
is turned. By like cause turning the wheel to the left
turns the machine to the left.
Automatic Control of Wings.
There are two wing tips, each of 6 feet spread (length)
and 2 feet from front to rear. These are hinged half
way between the main surfaces to the two outermost
rear struts. Cables run from these to an automatic
device working with power from the engine, which automatically
operates the tips with the tilting of the
machine. Normally the wing tips are held horizontal
by stiff springs introduced in the cables outside of the
device.
It was the successful working of this device which
righted the Van Anden craft when it was overturned in
the squall of October 19th, 1909. Previous to that
occurrence Mr. Van Anden had looked upon the device
as purely experimental, and had admitted that he had
grave uncertainty as to how it would operate in time of
emergency. He is now quoted as being thoroughly satisfied
with its practicability. It is this automatic device
which gives the Van Anden machine at least one distinctively
new feature.
While on this subject it will not be amiss to add that
Mr. Curtiss does not look kindly on automatic control.
"I would rather trust to my own action than that of a
machine," he says. This is undoubtedly good logic so
far as Mr. Curtiss is concerned, but all aviators are not
so cool-headed and resourceful.
Motive Power of Van Anden.
A 50-horsepower "H-F" water cooled motor drives a
laminated wood propeller 6 feet in diameter, with a 17
degree pitch at the extremities, increasing toward the
hub. The rear end of the motor is about 6 inches back
from the rear transverse beam and the engine shaft is
in a direct line with the axes of the two horizontal rudders.
An R. I. V. ball bearing carries the shaft at this
point. Flying, the motor turns at about 800 revolutions
per minute, delivering 180 pounds pull. A test of the
motor running at 1,200 showed a pull of 250 pounds on
the scales.
Still Another New Aeroplane.
Another new aeroplane is that produced by A. M.
Herring (an old-timer) and W. S. Burgess, under the
name of the Herring-Burgess. This is also equipped
with an automatic stability device for maintaining the
balance transversely. The curvature of the planes is
also laid out on new lines. That this new plan is
effective is evidenced by the fact that the machine has
been elevated to an altitude of 40 feet by using one-half
the power of the 30-horsepower motor.
The system of rudder and elevation control is very
simple. The aviator sits in front of the lower plane,
and extending his arms, grasps two supports which extend
down diagonally in front. On the under side of
these supports just beneath his fingers are the controls
which operate the vertical rudder, in the rear. Thus, if
he wishes to turn to the right, he presses the control
under the fingers of his right hand; if to the left, that
under the fingers of his left hand. The elevating rudder
is operated by the aviator's right foot, the control
being placed on a foot-rest.
Motor Is Extremely Light.
Not the least notable feature of the craft is its motor.
Although developing, under load, 30-horsepower, or that
of an ordinary automobile, it weighs, complete, hardly
100 pounds. Having occasion to move it a little distance
for inspection, Mr. Burgess picked it up and walked
off with it--cylinders, pistons, crankcase and all, even
the magneto, being attached. There are not many 30-
horsepower engines which can be so handled. Everything
about it is reduced to its lowest terms of simplicity,
and hence, of weight. A single camshaft operates
not only all of the inlet and exhaust valves, but the magneto
and gear water pump, as well. The motor is placed
directly behind the operator, and the propeller is directly
mounted on the crankshaft.
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