04.29.08
Posted in Uncategorized at 2:51 am by admin
For men who may have had some experience in the assembly of airplanes
at factories, or of rigging them at flying-fields, there is great
opportunity. Expert riggers who know their craft are few and hard to
get. They are invaluable for maintaining a machine in flying
condition. The use of airplanes in this country will require men for
rigging, for truing up the wires and struts. Each airplane must be
overhauled after a few hours of flight to discover hidden weaknesses
and to tighten sagging wires.
Rigging an airplane has some resemblance to rigging a ship for
sailing. The first requisite is to see that the machine is properly
balanced in flying position. There is a number of minute measurements
which come with the blue-print of every machine and which must be
followed out to the letter to get the most successful results. An
important detail is the pitch of the planes, or the angle of
incidence, as it is called. This is the angle which a plane makes with
the air in the direction of its motion. Too great a pitch will slow up
the machine by offering too great a resistance to the air; too small
an angle will not generate enough lift. The tail plane must be
attached with special care for its position. Its angle of incidence
must exactly balance the plane, and it must be bolted on so that there
is no chance of it cracking off under strain.
Radio operators will be in great demand for flying. Brig.-Gen. A.C.
Critchley, the youngest general officer in the British service, who
was a pilot in the Royal Air Force, said that the future development
of the airplane must go hand in hand with the development of wireless
communication. He added that the most difficult thing about flying,
especially ocean flying, was to keep the course in heavy weather.
There are no factors which will help a man on “dead” reckoning; and a
shift in wind, unknown to the navigator of a plane, will carry him
hundreds of miles from his objective. The wireless telephone was used
to some extent during the war for communication between the ground and
the air; it will be used to a greater extent in the next few years.
Permalink
04.26.08
Posted in Uncategorized at 5:31 pm by admin
In the early days of aeroplaning, when accidents
came thick and fast, the most usual explanation
which came from the pilot, when he recovered,
was: “I pushed the lever too far.”
Hundreds of trial machines were built, when
man learned that he could fly, and in every instance,
it is safe to say, the experimenter made the
most strenuous exertion to get up in the air the
first time the machine was put on the trial ground.
It is a wonder that accidents were not recorded
by the hundreds, instead of by the comparatively
few that were heard from. It was very discouraging,
no doubt, that the machines would not fly,
but that all of them, if they had sufficient power,
would fly, there can be no doubt.
HOW TO PRACTICE.–Absolute familiarity with
every part of the machine and conditions is the
first thing. The machine is brought out, and the
engine tested, the machine being held in leash
while this is done. It is then throttled down so
that the power of the engine will be less than is
necessary to raise the machine from the ground.
THE FIRST STAGE.–Usually it will require over
25 miles an hour to raise the machine. The engine
is set in motion, and now, for the first time a new
sensation takes possession of you, for the reason
that you are cut off from communication with
those around you as absolutely as though they
were a hundred miles away.
This new dependence on yourself is, in itself,
one of the best teachers you could have, because
it begins to instill confidence and control. As the
machine darts forward, going ten or fifteen miles
an hour, with the din of the engine behind you,
and feeling the rumbling motion of the wheels
over the uneven surface of the earth, you have the
sensation of going forty miles an hour.
The newness of the first sensation, which is
always under those conditions very much augmented
in the mind, wears away as the machine
goes back and forth. There is only one control
that requires your care, namely, to keep it on a
straight course. This is easy work, but you are
learning to make your control a reflex action,–to
do it without exercising a distinct will power.
PATIENCE THE MOST DIFFICULT THING.–If you
have the patience, as you should, to continue this
running practice, until you absolutely eliminate
the right and left control, as a matter of thought,
occasionally, if the air is still turning the machine,
and eventually, bringing it back, by turning
it completely around, while skimming the ground,
you will be ready for the second stage in the
trials.
THE SECOND STAGE.–The engine is now arranged
so that it will barely lift, when running
at its best. After the engine is at full speed, and
you are sure the machine is going fast enough,
the elevator control is turned to point the machine
in the air. It is a tense moment. You are on the
alert.
Permalink
04.23.08
Posted in Uncategorized at 9:51 am by admin
It has never been tried with power, and it is
doubtful whether it would be successful as a sustaining
surface for flying machines, for the same
reasons that caused failure with the box-like formation
of the Voison Machine.
THE DELTOID.–The deltoid is the simplest, and
the most easily constructed of all the kites. It is
usually made from stiff cardboard, A-shaped in
outline, as shown in Figs. 44 and 45, and bent along
a central line, as at A, forming two wings, each
of which is a right-angled triangle.
_Fig. 44. and 45. Deltoid Formation._
The peculiarity of this formation is, that it has
remarkable stability when used as a kite, with
either end foremost. If a small weight is placed
at the pointed end, and it is projected through the
air, it will fly straight, and is but little affected
by cross currents.
THE DUNNE FLYING MACHINE.–A top view of
this biplane is shown in Fig. 46. The A-shaped
disposition of the planes, gives it good lateral
stability, but it has the disadvantage under which
all aeroplanes labor, that the entire body of the
machine must move on a fore and aft vertical
plan in order to ascend or descend.
_Fig. 46. The Dunne Bi-plane._
This is a true deltoid formation, as the angle of
incidence of the planes is so disposed that when
the planes are horizontal from end to end, the inclination
is such as to make it similar to the deltoid
kite referred to.
ROTATING KITE.–A type of kite unlike the
others illustrated is a rotating structure, which
gives great stability, due to the gyroscopic action
on the supporting surfaces.
Fig. 47 shows a side view with the top in section.
The supporting surface is umbrella-shaped.
In fact, the ordinary umbrella will answer if not
dished too much. An angularly-bent piece of wire
A, provided with loops B, B, at the ends, serve as
bearings for the handle of the umbrella.
At the bend of the wire loop C, the cord D is
attached. The lower side of the umbrella top has
cup-shaped pockets E, near the margin, so arranged
that their open ends project in the same
direction, and the wind catching them rotates the
circular plane.
_Fig. 47. Rotable Umbrella Kite._
Permalink
04.20.08
Posted in Uncategorized at 4:21 am by admin
Apparently his release made a difference in the centre of
gravity, for Le Bris could not manipulate his levers for further
ascent; by skilful manipulation he retarded the descent
sufficiently to escape injury to himself; the machine descended
at an angle, so that one wing, striking the ground in front of
the other, received a certain amount of damage.
It may have been on account of the reluctance of this same or
another driver that Le Bris chose a different method of
launching himself in making a second experiment with his
albatross. He chose the edge of a quarry which had been
excavated in a depression of the ground; here he assembled his
apparatus at the bottom of the quarry, and by means of a rope
was hoisted to a height of nearly 100 ft. from the quarry
bottom, this rope being attached to a mast which he had erected
upon the edge of the depression in which the quarry was
situated. Thus hoisted, the albatross was swung to face a
strong breeze that blew inland, and Le Bris manipulated his
levers to give the front edges of his wings a downward angle, so
that only the top surfaces should take the wing pressure. Having
got his balance, he obtained a lifting angle of incidence on the
wings by means of his levers, and released the hook that secured
the machine, gliding off over the quarry. On the glide he met
with the inevitable upward current of air that the quarry and
the depression in which it was situated caused; this current
upset the balance of the machine and flung it to the bottom of
the quarry, breaking it to fragments. Le Bris, apparently as
intrepid as ingenious, gripped the mast from which his levers
were worked, and, springing upward as the machine touched earth,
escaped with no more damage than a broken leg. But for the
rebound of the levers he would have escaped even this.
The interest of these experiments is enhanced by the fact that
Le Bris was a seafaring man who conducted them from love of the
science which had fired his imagination, and in so doing
exhausted his own small means. It was in 1855 that he made
these initial attempts, and twelve years passed before his
persistence was rewarded by a public subscription made at Brest
for the purpose of enabling him to continue his experiments. He
built a second albatross, and on the advice of his friends
ballasted it for flight instead of travelling in it himself. It
was not so successful as the first, probably owing to the lack
of human control while in flight; on one of the trials a height
of 150 ft. was attained, the glider being secured by a thin rope
and held so as to face into the wind. A glide of nearly an
eighth of a mile was made with the rope hanging slack, and, at
the end of this distance, a rise in the ground modified the
force of the wind, whereupon the machine settled down without
damage. A further trial in a gusty wind resulted in the
complete destruction of this second machine; Le Bris had no more
funds, no further subscriptions were likely to materialise, and
so the experiments of this first exponent of the art of gliding
(save for Besnier and his kind) came to an end. They
constituted a notable achievement, and undoubtedly Le Bris
deserves a better place than has been accorded him in the ranks
of the early experimenters.
Permalink
04.17.08
Posted in Uncategorized at 4:01 pm by admin
This book makes no pretence of going minutely into the technical
and scientific sides of human flight: rather does it deal mainly
with the real achievements of pioneers who have helped to make
aviation what it is to-day.
My chief object has been to arouse among my readers an
intelligent interest in the art of flight, and, profiting by
friendly criticism of several of my former works, I imagine that
this is best obtained by setting forth the romance of triumph in
the realms of an element which has defied man for untold
centuries, rather than to give a mass of scientific principles
which appeal to no one but the expert.
So rapid is the present development of aviation that it is
difficult to keep abreast with the times. What is new to-day
becomes old to-morrow. The Great War has given a tremendous
impetus to the strife between the warring nations for the mastery
of the air, and one can but give a rough and general impression
of the achievements of naval and military airmen on the various
fronts.
Finally, I have tried to bring home the fact that the fascinating
progress of aviation should not be confined entirely to the
airman and constructor of air-craft; in short, this progress is
not a retord of events in which the mass of the nation have
little personal concern, but of a movement in which each one of
us may take an active and intelligent part.
I have to thank various aviation firms, airmen, and others who
have kindly come to my assistance, either with the help of
valuable information or by the loan of photographs. In
particular, my thanks are due to the Royal Flying Corps and Royal
Naval Air Service for permission to reproduce illustrations
from their two publications on the work and training of their
respective corps; to the Aeronautical Society of Great Britain;
to Messrs. C. G. Spencer & Sons, Highbury; The Sopwith Aviation
Company, Ltd.; Messrs. A. V. Roe & Co., Ltd.; The Gnome Engine
Company; The Green Engine Company; Mr. A. G. Gross (Geographia,
Ltd.); and M. Bleriot; for an exposition of the
internal-combustion engine I have drawn on Mr. Hornes The Age of
Machinery.
PART I. BALLOONS AND AIR-SHIPS
I. MANS DUEL WITH NATURE
II. THE FRENCH PAPER-MAKER WHO INVENTED THE BALLOON
III. THE FIRST MAN TO ASCEND IN A BALLOON
IV. THE FIRST BALLOON ASCENT IN ENGLAND
V. THE FATHER OF BRITISH AERONAUTS
VI. THE PARACHUTE
VII. SOME BRITISH INVENTORS OF AIR-SHIPS
VIII. THE FIRST ATTEMPTS TO STEER A BALLOON
IX. THE STRANGE CAREER OF COUNT ZEPPELIN
X. A ZEPPELIN AIR-SHIP AND ITS CONSTRUCTION
XI. THE SEMI-RIGID AIR-SHIP
XII. A NON-RIGID BALLOON
XIII. THE ZEPPELIN AND GOTHA RAIDS
PART II. AEROPLANES AND AIRMEN
XIV. EARLY ATTEMPTS IN AVIATION
XV. A PIONEER IN AVIATION
XVI. THE “HUMAN BIRDS”
XVII. THE AEROPLANE AND THE BIRD
XVIII. A GREAT BRITISH INVENTOR OF AEROPLANES
XIX. THE WRIGHT BROTHERS AND THEIR SECRET EXPERIMENTS
XX. THE INTERNAL-COMBUSTION ENGINE
XXI. THE INTERNAL-COMBUSTION ENGINE (Cont.)
XXII. THE AEROPLANE ENGINE
XXIII. A FAMOUS BRITISH INVENTOR OF AVIATION ENGINES
XXIV. THE WRIGHT BIPLANE (CAMBER OF PLANES)
XXV. THE WRIGHT BIPLANE (Cont.)
XXVI. HOW THE WRIGHTS LAUNCHED THEIR BIPLANE
XXVII. THE FIRST MAN TO FLY IN EUROPE
XXVIII. M. BLARIOT AND THE MONOPLANE
XXIX. HENRI FARMAN AND THE VOISIN BIPLANE
XXX. A FAMOUS BRITISH INVENTOR
XXXI. THE ROMANCE OF A COWBOY AERONAUT
XXXII. THREE HISTORIC FLIGHTS
XXXIII. THREE HISTORIC FLIGHTS (Cont.
XXXIV. THE HYDROPLANE AND AIR-BOAT
XXXV. A FAMOUS BRITISH INVENTOR OF THE WATER-PLANE
XXXVI. SEA-PLANES FOR WARFARE
XXXVII. THE FIRST MAN TO FLY IN BRITAIN
XXXVIII.THE R.F.C. AND R.N.A.S.
XXXIX. AEROPLANES IN THE GREAT WAR
XL. THE ATMOSPHERE AND THE BAROMETER
XLI. HOW AN AIRMAN KNOWS WHAT HEIGHT HE REACHES
XLII. HOW AN AIRMAN FINDS HIS WAY
Permalink
04.14.08
Posted in Uncategorized at 12:11 pm by admin
But though you may be quite familiar with the mechanism of this
engine, it does not follow that you know how the petrol engine
works, for the two are highly dissimilar. It is well, therefore,
that we include a short description of the internal-combustion
engine such as is applied to motor-cars, for then we shall be
able to understand the principles of the aeroplane engine.
At present petrol is the chief fuel used for the motor engine.
Numerous experiments have been tried with other fuels, such as
benzine, but petrol yields the best results.
Petrol is distilled from oil which comes from wells bored deep
down in the ground in Pennsylvania, in the south of Russia, in
Burma, and elsewhere. Also it is distilled in Scotland from
oil shale, from which paraffin oil and wax and similar substances
are produced. When the oil is brought to the surface it contains
many impurities, and in its native form is unsuitable for motor
engines. The crude oil is composed of a number of different
kinds of oil; some being light and clear, others heavy and thick.
To purify the oil it is placed in a large metal vessel or
“still”. Steam is first passed over the oil in the still, and
this changes the lightest of the oils into vapours. These vapours are sent through a series of pipes surrounded with cold
water, where they are cooled and become liquid again. Petrol is
a mixture of these lighter products of the oil.
If petrol be placed in the air it readily turns into a vapour,
and this vapour is extremely inflammable. For this reason petrol
is always kept in sealed tins, and very large quantities are not
allowed to be stored near large towns. The greatest care has to
be exercised in the use of this “unsafe” spirit. For example, it
is most dangerous to smoke when filling a tank with petrol, or to
use the spirit near a naked light. Many motor-cars have been set
on fire through the petrol leaking out of the tank in which it is
carried.
Permalink
04.11.08
Posted in Uncategorized at 8:12 am by admin
As in the case of aeroplane flight, as soon as the balloon was
proved practicable the flight across the English Channel was
talked of, and Rozier, who had the honour of the first flight,
announced his intention of being first to cross. But Blanchard,
who had an idea for a flying car, anticipated him, and made a
start from Dover on January 7th, 1785, taking with him an
American doctor named Jeffries. Blanchard fitted out his craft
for the journey very thoroughly, taking provisions, oars, and
even wings, for propulsion in case of need. He took so much, in
fact, that as soon as the balloon lifted clear of the ground the
whole of the ballast had to be jettisoned, lest the balloon
should drop into the sea. Half-way across the Channel the
sinking of the balloon warned Blanchard that he had to part with
more than ballast to accomplish the journey, and all the
equipment went, together with certain books and papers that were
on board the car. The balloon looked perilously like
collapsing, and both Blanchard and Jeffries began to undress in
order further to lighten their craft–Jeffries even proposed a
heroic dive to save the situation, but suddenly the balloon rose
sufficiently to clear the French coast, and the two voyagers
landed at a point near Calais in the Forest of Gaines, where a
marble column was subsequently erected to commemorate the great
feat.
Rozier, although not first across, determined to be second, and
for that purpose he constructed a balloon which was to owe its
buoyancy to a combination of the hydrogen and hot air
principles. There was a spherical hydrogen balloon above, and
beneath it a cylindrical container which could be filled with
hot air, thus compensating for the leakage of gas from the
hydrogen portion of the balloon–regulating the heat of his
fire, he thought, would give him perfect control in the matter of
ascending and descending.
On July 6th, 1785, a favourable breeze gave Rozier his
opportunity of starting from the French coast, and with a
passenger aboard he cast off in his balloon, which he had named
the Aero-Montgolfiere. There was a rapid rise at first, and
then for a time the balloon remained stationary over the land,
after which a cloud suddenly appeared round the balloon,
denoting that an explosion had taken place. Both Rozier and his
companion were killed in the fall, so that he, first to leave
the earth by balloon, was also first victim to the art of
aerostation.
There followed, naturally, a lull in the enthusiasm with which
ballooning had been taken up, so far as France was concerned.
In Italy, however, Count Zambeccari took up hot-air ballooning,
using a spirit lamp to give him buoyancy, and on the first
occasion when the balloon car was set on fire Zambeccari let
down his passenger by means of the anchor rope, and managed to
extinguish the fire while in the air. This reduced the buoyancy
of the balloon to such an extent that it fell into the Adriatic
and was totally wrecked, Zambeccari being rescued by fishermen.
He continued to experiment up to 1812, when he attempted to
ascend at Bologna; the spirit in his lamp was upset by the
collision of the car with a tree, and the car was again set on
fire. Zambeccari jumped from the car when it was over fifty feet
above level ground, and was killed. With him the Rozier type of
balloon, combining the hydrogen and hot air principles,
disappeared; the combination was obviously too dangerous to be
practical.
The brothers Robert were first to note how the heat of the sun
acted on the gases within a balloon envelope, and it has since
been ascertained that sun rays will heat the gas in a balloon to
as much as 80 degrees Fahrenheit greater temperature than the
surrounding atmosphere; hydrogen, being less affected by change
of temperature than coal gas, is the most suitable filling
element, and coal gas comes next as the medium of buoyancy. This
for the free and non-navigable balloon, though for the airship,
carrying means of combustion, and in military work liable to
ignition by explosives, the gas helium seems likely to replace
hydrogen, being non-combustible.
Permalink
04.09.08
Posted in Uncategorized at 10:11 pm by admin
France, and Curtiss in America. In view of the approaching
importance of amphibious seaplanes, mention should be made of the
flying boat (or bat boat as it was called, following Rudyard
Kipling) which was built by Sopwith in 1913 with a wheeled
landing-carriage which could be wound up above the bottom surface
of the boat so as to be out of the way when alighting on water.
During 1913 the (at one time almost universal) practice
originated by the Wright Brothers, of warping the wings for
lateral stability, began to die out and the bulk of aeroplanes
began to be fitted with flaps (or ailerons) instead. This
was a distinct change for the better, as continually warping the
wings by bending down the extremities of the rear spars was
bound in time to produce fatigue in that member and lead to
breakage; and the practice became completely obsolete during the
next two or three years.
The Gordon-Bennett race of September, 1913, was again won by
a Deperdussin machine, somewhat similar to that of the previous
year, but with exceedingly small wings, only 107 square feet in
area. The shape of these wings was instructive as showing how
what, from the general utility point of view, may be
disadvantageous can, for a special purpose, be turned to
account. With a span of 21 feet, the chord was 5 feet, giving
the inefficient aspect ratio of slightly over 4 to 1 only.
The object of this was to reduce the lift, and therefore the
resistance, to as low a point as possible. The total weight was
1,500 lbs., giving a wing-loading of 14 lbs. per square foot–a
hitherto undreamt-of figure. The result was that the machine
took an enormously long run before starting; and after touching
the ground on landing ran for nearly a mile before stopping; but
she beat all records by attaining a speed of 126 miles per
hour. Where this performance is mainly interesting is in
contrast to the machines of 1920, which with an even higher
speed capacity would yet be able to land at not more than 40 or
50 miles per hour, and would be thoroughly efficient flying
machines.
The Rheims Aviation Meeting, at which the Gordon-Bennett race
was flown, also saw the first appearance of the Morane Parasol
monoplane. The Morane monoplane had been for some time an
interesting machine as being the only type which had no fixed
surface in rear to give automatic stability, the movable
elevator being balanced through being hinged about one-third of
the way back from the front edge. This made the machine
difficult to fly except in the hands of experts, but it was very
quick and handy on the controls and therefore useful for racing
purposes. In the Parasol the modification was introduced of
raising the wing above the body, the pilot looking out beneath
it, in order to give as good a view as possible.
Before passing to the year 1914 mention should be made of the
feat performed by Nesteroff, a Russian, and Pegoud, a French
pilot, who were the first to demonstrate the possibilities of
flying upside-down and looping the loop. Though perhaps not
coming strictly within the purview of a chapter on design
(though certain alterations were made to the top wing-bracing of
the machine for this purpose) this performance was of extreme
importance to the development of aviation by showing the
possibility of recovering, given reasonable height, from any
position in the air; which led designers to consider the extra
stresses to which an aeroplane might be subjected and to take
steps to provide for them by increasing strength where
necessary.
When the year 1914 opened a speed of 126 miles per hour had been
attained and a height of 19,600 feet had been reached. The
Sopwith and Avro (the forerunner of the famous training machine
of the War period) were probably the two leading tractor
biplanes of the world, both two-seaters with a speed variation
from 40 miles per hour up to some 90 miles per hour with 80
horse-power engines. The French were still pinning their faith
mainly to monoplanes, while the Germans were beginning to come
into prominence with both monoplanes and biplanes of the Taube
type. These had wings swept backward and also upturned at the
wing-tips which, though it gave a certain measure of automatic
stability, rendered the machine somewhat clumsy in the air, and
their performances were not on the whole as high as those of
either France or Great Britain.
Permalink
04.07.08
Posted in Uncategorized at 3:41 pm by admin
DETERMINING THE PRESSURE FROM THE SPEED.–
These two instruments can be made to check each
other and thus pretty accurately enable you to
determine the proper places to mark the pressure
indicator, as well as to make the wheels in the
anemometer the proper size to turn the pointer
in seconds when the wind is blowing at a certain
speed, say ten miles per hour.
Suppose the air pressure indicator has the scale
divided into quarter pound marks. This will
make it accurate enough for all purposes.
CALCULATING PRESSURES FROM SPEED.–The following
table will give the pressures from 5 to 100
miles per hour:
Velocity of wind in Pressure Velocity of wind in Pressure
miles per hour per sq. ft. miles per hour per sq ft
5 .112 55 15.125
10 .500 60 18.000
15 1.125 65 21.125
20 2.000 70 22.500
25 3.125 75 28.125
30 4.600 80 32.000
35 6.126 86 36.126
40 8.000 90 40.500
45 10.125 95 45.125
50 12.5 100 50.000
HOW THE FIGURES ARE DETERMINED.–The foregoing
figures are determined in the following manner:
As an example let us assume that the velocity
of the wind is forty-five miles per hour. If
this is squared, or 45 multiplied by 45, the product
is 2025. In many calculations the mathematician
employs what is called a constant, a figure that
never varies, and which is used to multiply or
divide certain factors.
In this case the constant is 5/1000, or, as usually
written, .005. This is the same as one two hundredths
of the squared figure. That would make
the problem as follows:
45 X 45 = 2025 / 200 = 10.125; or,
45 X 45 - 2025 X .005 = 10.125.
Again, twenty-five miles per hour would be
25 X 25 = 625; and this multiplied by .005 equals
2 pounds pressure.
CONVERTING HOURS INTO MINUTES.–It is sometimes
confusing to think of miles per hour, when
you wish to express it in minutes or seconds. A
simple rule, which is not absolutely accurate, but
is correct within a few feet, in order to express
the speed in feet per minute, is to multiply the
figure indicating the miles per hour, by 8 3/4.
To illustrate: If the wind is moving at the
rate of twenty miles an hour, it will travel in that
time 105,600 feet (5280 X 20). As there are sixty
minutes in an hour, 105,600 divided by 60, equals
1760 feet per minute. Instead of going through
all this process of calculating the speed per minute,
remember to multiply the speed in miles per
hour by 90, which will give 1800 feet.
Permalink
04.04.08
Posted in Uncategorized at 11:41 am by admin
It must be obvious to the novice that the lower
the weight the less liability of overturning.
FORE AND AFT OSCILLATIONS.–The answer is,
that when the weight is placed below the planes it
acts like a pendulum. When the machine is traveling
forward, and the propeller ceases its motion,
as it usually does instantaneously, the weight, being
below, and having a certain momentum, continues
to move on, and the plane surface meeting
the resistance just the same, and having no means
to push it forward, a greater angle of resistance is
formed.
In Fig. 19 this action of the two forces is illustrated. The
plane at the speed of 30 miles is at
an angle of 15 degrees, the body B of the machine
being horizontal, and the weight C suspended directly
below the supporting surfaces.
The moment the power ceases the weight continues
moving forwardly, and it swings the forward
end of the frame upwardly, Fig. 20, and we now
have, as in the second figure, a new angle of incidence,
which is 30 degrees, instead of 12. It will
be understood that in order to effect a change in
the position of the machine, the forward end ascends,
as shown by the dotted line A.
_Fig. 20. Action when Propeller ceases to pull._
The weight a having now ascended as far as
possible forward in its swing, and its motion
checked by the banking action of the plan it will
again swing back, and again carry with it the
frame, thus setting up an oscillation, which is extremely
dangerous.
The tail E, with its unchanged angle, does not,
in any degree, aid in maintaining the frame on
an even keel. Being nearly horizontal while in
flight, if not at a negative angle, it actually assists
the forward end of the frame to ascend.
APPLICATION OF THE NEW PRINCIPLE.–Extending
the application of the suggested form, let us see
wherein it will prevent this pendulous motion at
the moment the power ceases to exert a forwardly-
propelling force.
_Fig. 21. Synchronously moving Planes._
In Fig. 21 the body A is shown to be equipped
with the supporting plane B and the tail a, so
they are adjustable simultaneously at the same
angle, and the weight D is placed below, similar to
the other structure.
At every moment during the forward movement
of this type of structure, the rear end of
the machine has a tendency to move upwardly,
the same as the forward end, hence, when the
weight seeks, in this case to go on, it acts on the
rear plane, or tail, and causes that end to raise,
and thus by mutual action, prevents any pendulous
swing.
LOW WEIGHT NOT NECESSARY WITH SYNCHRONOUSLY-MOVING WINGS.
–A little reflection will convince
any one that if the two wings move in harmony,
the weight does not have to be placed low,
and thus still further aid in making a compact
machine. By increasing the area of the tail, and
making that a true supporting surface, instead of
a mere idler, the weight can be moved further
back, the distance transversely across the planes
may be shortened, and in that way still further
increase the lateral stability.
CHAPTER V
DIFFERENT MACHINE TYPES AND THEIR CHARACTERISTICS
THERE are three distinct types of heavier-than-
air machines, which are widely separated in all
their characteristics, so that there is scarcely a
single feature in common.
Two of them, the aeroplane, and the orthopter,
have prototypes in nature, and are distinguished
by their respective similarities to the soaring
birds, and those with flapping wings.
The Helicopter, on the other hand, has no antecedent
type, but is dependent for its raising
powers on the pull of a propeller, or a plurality
of them, constructed, as will be pointed out hereinafter.
AEROPLANES.–The only form which has met
with any success is the aeroplane, which, in
practice, is made in two distinct forms, one with
a single set of supporting planes, in imitation of
birds, and called a monoplane; and the other having
two wings, one above the other, and called
the bi-plane, or two-planes.
All machines now on the market which do not
depend on wing oscillations come under those
types.
THE MONOPLANE.–The single plane type has
some strong claims for support. First of these
is the comparatively small head resistance, due
to the entire absence of vertical supporting posts,
which latter are necessary with the biplane type.
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