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Flying Machines: Construction and Operation

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How to Distribute the Weight.

Let us take 1,030 pounds as the net weight of the machine
as against the same average in the Wright and
Curtiss machines. Now comes the question of distributing
this weight between the framework, motor, and
other equipment. As a general proposition the framework
should weigh about twice as much as the complete
power plant (this is for amateur work).

The word "framework" indicates not only the wooden
frames of the main planes, auxiliary planes, rudders,
etc., but the cloth coverings as well--everything in fact
except the engine and propeller.

On the basis named the framework would weigh 686
pounds, and the power plant 344. These figures are
liberal, and the results desired may be obtained well
within them as the novice will learn as he makes progress
in the work.

Figuring on Surface Area.

It was Prof. Langley who first brought into prominence
in connection with flying machine construction the
mathematical principle that the larger the object the
smaller may be the relative area of support. As explained
in Chapter XIII, there are mechanical limits as
to size which it is not practical to exceed, but the main
principle remains in effect.

Take two aeroplanes of marked difference in area of
surface. The larger will, as a rule, sustain a greater
weight in relative proportion to its area than the smaller
one, and do the work with less relative horsepower. As
a general thing well-constructed machines will average
a supporting capacity of one pound for every one-half
square foot of surface area. Accepting this as a working
rule we find that to sustain a weight of 1,200 pounds
--machine and two passengers--we should have 600
square feet of surface.

Distributing the Surface Area.

The largest surfaces now in use are those of the
Wright, Voisin and Antoinette machines--538 square
feet in each. The actual sustaining power of these machines,
so far as known, has never been tested to the
limit; it is probable that the maximum is considerably
in excess of what they have been called upon to show.
In actual practice the average is a little over one pound
for each one-half square foot of surface area.

Allowing that 600 square feet of surface will be used,
the next question is how to distribute it to the best
advantage. This is another important matter in which
individual preference must rule. We have seen how
the professionals disagree on this point, some using
auxiliary planes of large size, and others depending upon
smaller auxiliaries with an increase in number so as to
secure on a different plan virtually the same amount of

In deciding upon this feature the best thing to do is
to follow the plans of some successful aviator, increasing
the area of the auxiliaries in proportion to the increase
in the area of the main planes. Thus, if you use 600
square feet of surface where the man whose plans you
are following uses 500, it is simply a matter of making
your planes one-fifth larger all around.

The Cost of Production.

Cost of production will be of interest to the amateur
who essays to construct a flying machine. Assuming
that the size decided upon is double that of the glider
the material for the framework, timber, cloth, wire, etc.,
will cost a little more than double. This is because it
must be heavier in proportion to the increased size of
the framework, and heavy material brings a larger price
than the lighter goods. If we allow $20 as the cost of
the glider material it will be safe to put down the cost
of that required for a real flying machine framework
at $60, provided the owner builds it himself.

As regards the cost of motor and similar equipment
it can only be said that this depends upon the selection
made. There are some reliable aviation motors which
may be had as low as $500, and there are others which
cost as much as $2,000.

Services of Expert Necessary.

No matter what kind of a motor may be selected the
services of an expert will be necessary in its proper
installation unless the amateur has considerable genius
in this line himself. As a general thing $25 should be
a liberal allowance for this work. No matter how carefully
the engine may be placed and connected it will be
largely a matter of luck if it is installed in exactly the
proper manner at the first attempt. The chances are
that several alterations, prompted by the results of trials,
will have to be made. If this is the case the expert's bill may
readily run up to $50. If the amateur is competent to do this
part of the work the entire item of $50 may, of course, be cut

As a general proposition a fairly satisfactory flying machine,
one that will actually fly and carry the operator with it, may be
constructed for $750, but it will lack the better qualities which
mark the higher priced machines. This computation is made on
the basis of $60 for material, $50 for services of expert, $600
for motor, etc., and an allowance of $40 for extras.

No man who has the flying machine germ in his system will be long
satisfied with his first moderate price machine, no matter how
well it may work. It's the old story of the automobile "bug"
over again. The man who starts in with a modest $1,000 automobile
invariably progresses by easy stages to the $4,000 or $5,000
class. The natural tendency is to want the biggest and best
attainable within the financial reach of the owner.

It's exactly the same way with the flying machine
convert. The more proficient he becomes in the manipulation
of his car, the stronger becomes the desire to fly
further and stay in the air longer than the rest of his
brethren. This necessitates larger, more powerful, and
more expensive machines as the work of the germ progresses.

Speed Affects Weight Capacity.

Don't overlook the fact that the greater speed you
can attain the smaller will be the surface area you can
get along with. If a machine with 500 square feet of
sustaining surface, traveling at a speed of 40 miles an
hour, will carry a weight of 1,200 pounds, we can cut
the sustaining surface in half and get along with 250
square feet, provided a speed of 60 miles an hour can
be obtained. At 100 miles an hour only 80 square feet
of surface area would be required. In both instances the
weight sustaining capacity will remain the same as with
the 500 square feet of surface area--1,200 pounds.

One of these days some mathematical genius will
figure out this problem with exactitude and we will have
a dependable table giving the maximum carrying capacity
of various surface areas at various stated speeds,
based on the dimensions of the advancing edges. At
present it is largely a matter of guesswork so far as
making accurate computation goes. Much depends upon
the shape of the machine, and the amount of surface
offering resistance to the wind, etc.



Motors for flying machines must be light in weight,
of great strength, productive of extreme speed, and
positively dependable in action. It matters little
as to the particular form, or whether air or
water cooled, so long as the four features named are
secured. There are at least a dozen such motors or
engines now in use. All are of the gasolene type, and
all possess in greater or lesser degree the desired qualities.
Some of these motors are:

Renault--8-cylinder, air-cooled; 50 horse power;
weight 374 pounds.

Fiat--8-cylinder, air-cooled; 50 horse power; weight
150 pounds.

Farcot--8-cylinder, air-cooled; from 30 to 100 horse
power, according to bore of cylinders; weight of smallest,
84 pounds.

R. E. P.--10-cylinder, air-cooled; 150 horse power;
weight 215 pounds.

Gnome--7 and 14 cylinders, revolving type, air-cooled;
50 and 100 horse power; weight 150 and 300 pounds.

Darracq--2 to 14 cylinders, water cooled; 30 to 200
horse power; weight of smallest 100 pounds.

Wright--4-cylinder, water-cooled; 25 horse power;
weight 200 pounds.

Antoinette--8 and 16-cylinder, water-cooled; 50 and 100
horse power; weight 250 and 500 pounds.

E. N. V.--8-cylinder, water-cooled; from 30 to 80
horse power, according to bore of cylinder; weight 150
to 400 pounds.

Curtiss--8-cylinder, water-cooled; 60 horse power;
weight 300 pounds.

Average Weight Per Horse Power.

It will be noticed that the Gnome motor is unusually
light, being about three pounds to the horse power
produced, as opposed to an average of 4 1/2 pounds per
horse power in other makes. This result is secured by
the elimination of the fly-wheel, the engine itself revolving,
thus obtaining the same effect that would be produced
by a fly-wheel. The Farcot is even lighter, being
considerably less than three pounds per horse power,
which is the nearest approach to the long-sought engine
equipment that will make possible a complete flying
machine the total weight of which will not exceed one
pound per square foot of area.

How Lightness Is Secured.

Thus far foreign manufacturers are ahead of Americans
in the production of light-weight aerial motors, as
is evidenced by the Gnome and Farcot engines, both of
which are of French make. Extreme lightness is made
possible by the use of fine, specially prepared steel for
the cylinders, thus permitting them to be much thinner
than if ordinary forms of steel were used. Another big
saving in weight is made by substituting what are
known as "auto lubricating" alloys for bearings. These
alloys are made of a combination of aluminum and magnesium.

Still further gains are made in the use of alloy steel
tubing instead of solid rods, and also by the paring away
of material wherever it can be done without sacrificing
strength. This plan, with the exclusive use of the best
grades of steel, regardless of cost, makes possible a
marked reduction in weight.

Multiplicity of Cylinders.

Strange as it may seem, multiplicity of cylinders does
not always add proportionate weight. Because a 4-
cylinder motor weighs say 100 pounds, it does not necessarily
follow that an 8-cylinder equipment will weigh
200 pounds. The reason of this will be plain when it
is understood that many of the parts essential to a 4-
cylinder motor will fill the requirements of an 8-cylinder
motor without enlargement or addition.

Neither does multiplying the cylinders always increase
the horsepower proportionately. If a 4-cylinder
motor is rated at 25 horsepower it is not safe to take
it for granted that double the number of cylinders will
give 50 horsepower. Generally speaking, eight cylinders,
the bore, stroke and speed being the same, will give
double the power that can be obtained from four, but
this does not always hold good. Just why this exception
should occur is not explainable by any accepted rule.

Horse Power and Speed.

Speed is an important requisite in a flying-machine
motor, as the velocity of the aeroplane is a vital factor
in flotation. At first thought, the propeller and similar
adjuncts being equal, the inexperienced mind would
naturally argue that a 50-horsepower engine should
produce just double the speed of one of 25-horsepower.
That this is a fallacy is shown by actual performances.
The Wrights, using a 25-horsepower motor, have made
44 miles an hour, while Bleriot, with a 50-horsepower
motor, has a record of a short-distance flight at the rate
of 52 miles an hour. The fact is that, so far as speed
is concerned, much depends upon the velocity of the
wind, the size and shape of the aeroplane itself, and the
size, shape and gearing of the propeller. The stronger
the wind is blowing the easier it will be for the aeroplane
to ascend, but at the same time the more difficult
it will be to make headway against the wind in a horizontal
direction. With a strong head wind, and proper
engine force, your machine will progress to a certain
extent, but it will be at an angle. If the aviator desired
to keep on going upward this would be all right, but
there is a limit to the altitude which it is desirable to
reach--from 100 to 500 feet for experts--and after that
it becomes a question of going straight ahead.

Great Waste of Power.

One thing is certain--even in the most efficient of
modern aerial motors there is a great loss of power between
the two points of production and effect. The
Wright outfit, which is admittedly one of the most effective
in use, takes one horsepower of force for the raising
and propulsion of each 50 pounds of weight. This,
for a 25-horsepower engine, would give a maximum lifting
capacity of 1250 pounds. It is doubtful if any of the
higher rated motors have greater efficiency. As an 8-
cylinder motor requires more fuel to operate than a 4-
cylinder, it naturally follows that it is more expensive
to run than the smaller motor, and a normal increase in
capacity, taking actual performances as a criterion, is
lacking. In other words, what is the sense of using an
8-cylinder motor when one of 4 cylinders is sufficient?

What the Propeller Does.

Much of the efficiency of the motor is due to the form
and gearing of the propeller. Here again, as in other
vital parts of flying-machine mechanism, we have a wide
divergence of opinion as to the best form. A fish makes
progress through the water by using its fins and tail;
a bird makes its way through the air in a similar manner
by the use of its wings and tail. In both instances the
motive power comes from the body of the fish or bird.

In place of fins or wings the flying machine is equipped
with a propeller, the action of which is furnished by the
engine. Fins and wings have been tried, but they don't

While operating on the same general principle, aerial
propellers are much larger than those used on boats.
This is because the boat propeller has a denser, more
substantial medium to work in (water), and consequently
can get a better "hold," and produce more propulsive
force than one of the same size revolving in the air.
This necessitates the aerial propellers being much larger
than those employed for marine purposes. Up to this
point all aviators agree, but as to the best form most of
them differ.

Kinds of Propellers Used.

One of the most simple is that used by Curtiss. It
consists of two pear-shaped blades of laminated wood,
each blade being 5 inches wide at its extreme point,
tapering slightly to the shaft connection. These blades
are joined at the engine shaft, in a direct line. The propeller
has a pitch of 5 feet, and weighs, complete, less
than 10 pounds. The length from end to end of the two
blades is 6 1/2 feet.

Wright uses two wooden propellers, in the rear of his
biplane, revolving in opposite directions. Each propeller
is two-bladed.

Bleriot also uses a two-blade wooden propeller, but
it is placed in front of his machine. The blades are each
about 3 1/2 feet long and have an acute "twist."

Santos-Dumont uses a two-blade wooden propeller,
strikingly similar to the Bleriot.

On the Antoinette monoplane, with which good records
have been made, the propeller consists of two spoon-
shaped pieces of metal, joined at the engine shaft in
front, and with the concave surfaces facing the machine.

The propeller on the Voisin biplane is also of metal,
consisting of two aluminum blades connected by a forged
steel arm.

Maximum thrust, or stress--exercise of the greatest
air-displacing force--is the object sought. This, according
to experts, is best obtained with a large propeller
diameter and reasonably low speed. The diameter is the
distance from end to end of the blades, which on the
largest propellers ranges from 6 to 8 feet. The larger
the blade surface the greater will be the volume of air
displaced, and, following this, the greater will be the
impulse which forces the aeroplane ahead. In all centrifugal
motion there is more or less tendency to disintegration
in the form of "flying off" from the center, and
the larger the revolving object is the stronger is this
tendency. This is illustrated in the many instances in
which big grindstones and fly-wheels have burst from
being revolved too fast. To have a propeller break
apart in the air would jeopardize the life of the aviator,
and to guard against this it has been found best to make
its revolving action comparatively slow. Besides this
the slow motion (it is only comparatively slow) gives
the atmosphere a chance to refill the area disturbed by
one propeller blade, and thus have a new surface for
the next blade to act upon.

Placing of the Motor.

As on other points, aviators differ widely in their
ideas as to the proper position for the motor. Wright
locates his on the lower plane, midway between the front
and rear edges, but considerably to one side of the exact
center. He then counter-balances the engine weight by
placing his seat far enough away in the opposite direction
to preserve the center of gravity. This leaves a
space in the center between the motor and the operator
in which a passenger may be carried without disturbing
the equilibrium.

Bleriot, on the contrary, has his motor directly in
front and preserves the center of gravity by taking his
seat well back, this, with the weight of the aeroplane,
acting as a counter-balance.

On the Curtiss machine the motor is in the rear, the
forward seat of the operator, and weight of the horizontal
rudder and damping plane in front equalizing the
engine weight.

No Perfect Motor as Yet.

Engine makers in the United States, England, France
and Germany are all seeking to produce an ideal motor
for aviation purposes. Many of the productions are
highly creditable, but it may be truthfully said that
none of them quite fill the bill as regards a combination
of the minimum of weight with the maximum of
reliable maintained power. They are all, in some respects,
improvements upon those previously in use, but
the great end sought for has not been fully attained.

One of the motors thus produced was made by the
French firm of Darracq at the suggestion of Santos Dumont, and on
lines laid down by him. Santos Dumont
wanted a 2-cylinder horizontal motor capable of developing
30 horsepower, and not exceeding 4 1/2 pounds per
horsepower in weight.

There can be no question as to the ability and skill
of the Darracq people, or of their desire to produce a
motor that would bring new credit and prominence to
the firm. Neither could anything radically wrong be
detected in the plans. But the motor, in at least one
important requirement, fell short of expectations.

It could not be depended upon to deliver an energy
of 30 horsepower continuously for any length of time.
Its maximum power could be secured only in "spurts."

This tends to show how hard it is to produce an ideal
motor for aviation purposes. Santos Dumont, of undoubted
skill and experience as an aviator, outlined definitely
what he wanted; one of the greatest designers
in the business drew the plans, and the famous house of
Darracq bent its best energies to the production. But
the desired end was not fully attained.

Features of Darracq Motor.

Horizontal motors were practically abandoned some
time ago in favor of the vertical type, but Santos Dumont
had a logical reason for reverting to them. He
wanted to secure a lower center of gravity than would
be possible with a vertical engine. Theoretically his
idea was correct as the horizontal motor lies flat, and
therefore offers less resistance to the wind, but it did not
work out as desired.

At the same time it must be admitted that this Darracq
motor is a marvel of ingenuity and exquisite workmanship.
The two cylinders, having a bore of 5 1-10
inches and a stroke of 4 7-10 inches, are machined out
of a solid bar of steel until their weight is only 8 4-5
pounds complete. The head is separate, carrying the
seatings for the inlet and exhaust valves, is screwed onto
the cylinder, and then welded in position. A copper
water-jacket is fitted, and it is in this condition that the
weight of 8 4-5 pounds is obtained.

On long trips, especially in regions where gasolene is
hard to get, the weight of the fuel supply is an important
feature in aviation. As a natural consequence flying
machine operators favor the motor of greatest economy
in gasolene consumption, provided it gives the necessary

An American inventor, Ramsey by name, is working
on a motor which is said to possess great possibilities
in this line. Its distinctive features include a connecting
rod much shorter than usual, and a crank shaft located
the length of the crank from the central axis of the
cylinder. This has the effect of increasing the piston
stroke, and also of increasing the proportion of the
crank circle during which effective pressure is applied
to the crank.

Making the connecting rod shorter and leaving the
crank mechanism the same would introduce excessive
cylinder friction. This Ramsey overcomes by the location
of his crank shaft. The effect of the long piston
stroke thus secured, is to increase the expansion of the
gases, which in turn increases the power of the engine
without increasing the amount of fuel used.

Propeller Thrust Important.

There is one great principle in flying machine propulsion
which must not be overlooked. No matter how
powerful the engine may be unless the propeller thrust
more than overcomes the wind pressure there can be
no progress forward. Should the force of this propeller
thrust and that of the wind pressure be equal the result
is obvious. The machine is at a stand-still so far
as forward progress is concerned and is deprived of the
essential advancing movement.

Speed not only furnishes sustentation for the airship,
but adds to the stability of the machine. An aeroplane
which may be jerky and uncertain in its movements, so
far as equilibrium is concerned, when moving at a slow
gait, will readily maintain an even keel when the speed
is increased.

Designs for Propeller Blades.

It is the object of all men who design propellers to
obtain the maximum of thrust with the minimum expenditure
of engine energy. With this purpose in view
many peculiar forms of propeller blades have been
evolved. In theory it would seem that the best effects
could be secured with blades so shaped as to present a
thin (or cutting) edge when they come out of the wind,
and then at the climax of displacement afford a maximum
of surface so as to displace as much air as possible.
While this is the form most generally favored
there are others in successful operation.

There is also wide difference in opinion as to the
equipment of the propeller shaft with two or more
blades. Some aviators use two and some four. All
have more or less success. As a mathematical proposition
it would seem that four blades should give more
propulsive force than two, but here again comes in one
of the puzzles of aviation, as this result is not always

Difference in Propeller Efficiency.

That there is a great difference in propeller efficiency
is made readily apparent by the comparison of effects
produced in two leading makes of machines--the Wright
and the Voisin.

In the former a weight of from 1,100 to 1,200 pounds
is sustained and advance progress made at the rate of
40 miles an hour and more, with half the engine speed
of a 25 horse-power motor. This would be a sustaining
capacity of 48 pounds per horsepower. But the actual
capacity of the Wright machine, as already stated, is 50
pounds per horsepower.

The Voisin machine, with aviator, weighs about 1,370
pounds, and is operated with a so-horsepower motor.
Allowing it the same speed as the Wright we find that,
with double the engine energy, the lifting capacity is
only 27 1/2 pounds per horsepower. To what shall we
charge this remarkable difference? The surface of the
planes is exactly the same in both machines so there
is no advantage in the matter of supporting area.

Comparison of Two Designs.

On the Wright machine two wooden propellers of
two blades each (each blade having a decided "twist")
are used. As one 25 horsepower motor drives both propellers the
engine energy amounts to just one-half of
this for each, or 12 1/2 horsepower. And this energy is
utilized at one-half the normal engine speed.

On the Voisin a radically different system is employed.
Here we have one metal two-bladed propeller with a
very slight "twist" to the blade surfaces. The full energy
of a 50-horsepower motor is utilized.

Experts Fail to Agree.

Why should there be such a marked difference in
the results obtained? Who knows? Some experts
maintain that it is because there are two propellers on
the Wright machine and only one on the Voisin, and
consequently double the propulsive power is exerted.
But this is not a fair deduction, unless both propellers
are of the same size. Propulsive power depends upon
the amount of air displaced, and the energy put into the
thrust which displaces the air.

Other experts argue that the difference in results may
be traced to the difference in blade design, especially
in the matter of "twist."

The fact is that propeller results depend largely upon
the nature of the aeroplanes on which they are used.
A propeller, for instance, which gives excellent results
on one type of aeroplane, will not work satisfactorily on

There are some features, however, which may be safely
adopted in propeller selection. These are: As extensive
a diameter as possible; blade area 10 to 15 per cent
of the area swept; pitch four-fifths of the diameter;
rotation slow. The maximum of thrust effort will be thus



In laying out plans for a flying machine the first thing
to decide upon is the size of the plane surfaces. The
proportions of these must be based upon the load to be
carried. This includes the total weight of the machine
and equipment, and also the operator. This will be a
rather difficult problem to figure out exactly, but
practical approximate figures may be reached.

It is easy to get at the weight of the operator, motor
and propeller, but the matter of determining, before they
are constructed, what the planes, rudders, auxiliaries,
etc., will weigh when completed is an intricate proposition.
The best way is to take the dimensions of some
successful machine and use them, making such alterations
in a minor way as you may desire.

Dimensions of Leading Machines.

In the following tables will be found the details as to
surface area, weight, power, etc., of the nine principal
types of flying machines which are now prominently before
the public:

Surface area Spread in Depth in
Make Passengers sq. feet linear feet linear
Santos-Dumont . . 1 110 16.0 26.0
Bleriot . . . . . 1 150.6 24.6 22.0
R. E. P . . . . . 1 215 34.1 28.9
Bleriot . . . . . 2 236 32.9 23.0
Antoinette. . . . 2 538 41.2 37.9
No. of Weight Without
Make Cylinders Horse Power Operator
Santos-Dumont. . 2 30 250 5.0
Bleriot. . . . . 3 25 680 6.9
R. E. P. . . . . 7 35 900 6.6
Bleriot. . . . . 7 50 1,240 8.1
Antoinette . . . 8 50 1,040 7.2

Surface Area Spread in Depth
Make Passengers sq. feet linear feet linear
Curtiss . . . 2 258 29.0
Wright. . . . 2 538 41.0
Farman. . . . 2 430 32.9
Voisin. . . . 2 538 37.9

No. of Weight Without
Make Cylinders Horse Power Operator
Curtiss . . . 8 50 600 6.0
Wright. . . . 4 25 1,100 8.1
Farman. . . . 7 50 1,200 8.9
Voisin. . . . 8 50 1,200 6.6

In giving the depth dimensions the length over all--
from the extreme edge of the front auxiliary plane to
the extreme tip of the rear is stated. Thus while the
dimensions of the main planes of the Wright machine
are 41 feet spread by 6 1/2 feet in depth, the depth over
all is 30.7.

Figuring Out the Details.

With this data as a guide it should be comparatively
easy to decide upon the dimensions of the machine required.
In arriving at the maximum lifting capacity the
weight of the operator must be added. Assuming this
to average 170 pounds the method of procedure would be
as follows:

Add the weight of the operator to the weight of the
complete machine. The new Wright machine complete
weighs 900 pounds. This, plus 170, the weight of the
operator, gives a total of 1,070 pounds. There are 538
square feet of supporting surface, or practically one
square foot of surface area to each two pounds of load.

There are some machines, notably the Bleriot, in which
the supporting power is much greater. In this latter
instance we find a surface area of 150 1/2 square feet
carrying a load of 680 plus 170, or an aggregate of 850
pounds. This is the equivalent of five pounds to the
square foot. This ratio is phenomenally large, and
should not be taken as a guide by amateurs.

The Matter of Passengers.

These deductions are based on each machine carrying
one passenger, which is admittedly the limit at present
of the monoplanes like those operated for record-making
purposes by Santos-Dumont and Bleriot. The biplanes,
however, have a two-passenger capacity, and this adds
materially to the proportion of their weight-sustaining
power as compared with the surface area. In the following
statement all the machines are figured on the
one-passenger basis. Curtiss and Wright have carried
two passengers on numerous occasions, and an extra 170
pounds should therefore be added to the total weight
carried, which would materially increase the capacity.
Even with the two-passenger load the limit is by no
means reached, but as experiments have gone no further
it is impossible to make more accurate figures.

Average Proportions of Load.

It will be interesting, before proceeding to lay out the
dimension details, to make a comparison of the proportion
of load effect with the supporting surfaces of various
well-known machines. Here are the figures:

Santos-Dumont--A trifle under four pounds per square

Bleriot--Five pounds.

R. E. P.--Five pounds.

Antoinette--About two and one-quarter pounds.

Curtiss--About two and one-half pounds.

Wright--Two and one-quarter pounds.

Farman--A trifle over three pounds.

Voisin--A little under two and one-half pounds.

Importance of Engine Power.

While these figures are authentic, they are in a way
misleading, as the important factor of engine power
is not taken into consideration. Let us recall the fact
that it is the engine power which keeps the machine in
motion, and that it is only while in motion that the machine
will remain suspended in the air. Hence, to attribute the support
solely to the surface area is erroneous.
True, that once under headway the planes contribute
largely to the sustaining effect, and are absolutely essential
in aerial navigation--the motor could not rise without
them--still, when it comes to a question of weight-
sustaining power, we must also figure on the engine

In the Wright machine, in which there is a lifting
capacity of approximately 2 1/4 pounds to the square foot
of surface area, an engine of only 25 horsepower is used.
In the Curtiss, which has a lifting capacity of 2 1/2
pounds per square foot, the engine is of 50 horsepower.
This is another of the peculiarities of aerial construction
and navigation. Here we have a gain of 1/4 pound in
weight-lifting capacity with an expenditure of double
the horsepower. It is this feature which enables Curtiss
to get along with a smaller surface area of supporting
planes at the expense of a big increase in engine power.
Proper Weight of Machine.

As a general proposition the most satisfactory machine
for amateur purposes will be found to be one with
a total weight-sustaining power of about 1,200 pounds.
Deducting 170 pounds as the weight of the operator,
this will leave 1,030 pounds for the complete motor-
equipped machine, and it should be easy to construct one
within this limit. This implies, of course, that due care
will be taken to eliminate all superfluous weight by using
the lightest material compatible with strength and safety.

This plan will admit of 686 pounds weight in the
frame work, coverings, etc., and 344 for the motor,
propeller, etc., which will be ample. Just how to distribute
the weight of the planes is a matter which must
be left to the ingenuity of the builder.

Comparison of Bird Power.

There is an interesting study in the accompanying
illustration. Note that the surface area of the albatross
is much smaller than that of the vulture, although the
wing spread is about the same. Despite this the albatross
accomplishes fully as much in the way of flight
and soaring as the vulture. Why? Because the albaboss is quicker
and more powerful in action. It is
the application of this same principle in flying machines
which enables those of great speed and power to get
along with less supporting surface than those of slower

Measurements of Curtiss Machine.

Some idea of framework proportion may be had from
the following description of the Curtiss machine. The
main planes have a spread (width) of 29 feet, and are
4 1/2 feet deep. The front double surface horizontal rudder
is 6x2 feet, with an area of 24 square feet. To the
rear of the main planes is a single surface horizontal
plane 6x2 feet, with an area of 12 square feet. In connection
with this is a vertical rudder 2 1/2 feet square.
Two movable ailerons, or balancing planes, are placed
at the extreme ends of the upper planes. These are 6x2
feet, and have a combined area of 24 square feet. There
is also a triangular shaped vertical steadying surface in
connection with the front rudder.

Thus we have a total of 195 square feet, but as the
official figures are 258, and the size of the triangular-
shaped steadying surface is unknown, we must take it
for granted that this makes up the difference. In the
matter of proportion the horizontal double-plane rudder
is about one-tenth the size of the main plane, counting
the surface area of only one plane, the vertical rudder
one-fortieth, and the ailerons one-twentieth.



Having constructed and equipped your machine, the
next thing is to decide upon the method of controlling
the various rudders and auxiliary planes by which the
direction and equilibrium and ascending and descending
of the machine are governed.

The operator must be in position to shift instantaneously the
position of rudders and planes, and also to control
the action of the motor. This latter is supposed to
work automatically and as a general thing does so with
entire satisfaction, but there are times when the supply
of gasolene must be regulated, and similar things done.
Airship navigation calls for quick action, and for this
reason the matter of control is an important one--it is
more than important; it is vital.

Several Methods of Control.

Some aviators use a steering wheel somewhat after
the style of that used in automobiles, and by this not
only manipulate the rudder planes, but also the flow of
gasolene. Others employ foot levers, and still others,
like the Wrights, depend upon hand levers.

Curtiss steers his aeroplane by means of a wheel, but
secures the desired stabilizing effect with an ingenious
jointed chair-back. This is so arranged that by leaning
toward the high point of his wing planes the aeroplane
is restored to an even keel. The steering post of the
wheel is movable backward and forward, and by this
motion elevation is obtained.

The Wrights for some time used two hand levers, one
to steer by and warp the flexible tips of the planes, the
other to secure elevation. They have now consolidated
all the functions in one lever. Bleriot also uses the
single lever control.

Farman employs a lever to actuate the rudders, but
manipulates the balancing planes by foot levers.

Santos-Dumont uses two hand levers with which to
steer and elevate, but manipulates the planes by means
of an attachment to the back of his outer coat.

Connection With the Levers.

No matter which particular method is employed, the
connection between the levers and the object to be manipulated
is almost invariably by wire. For instance, from
the steering levers (or lever) two wires connect with opposite
sides of the rudder. As a lever is moved so as to
draw in the right-hand wire the rudder is drawn to the
right and vice versa. The operation is exactly the same
as in steering a boat. It is the same way in changing
the position of the balancing planes. A movement of
the hands or feet and the machine has changed its
course, or, if the equilibrium is threatened, is back on
an even keel.

Simple as this seems it calls for a cool head, quick
eye, and steady hand. The least hesitation or a false
movement, and both aviator and craft are in danger.

Which Method is Best?

It would be a bold man who would attempt to pick
out any one of these methods of control and say it was
better than the others. As in other sections of aeroplane
mechanism each method has its advocates who dwell
learnedly upon its advantages, but the fact remains that
all the various plans work well and give satisfaction.

What the novice is interested in knowing is how the
control is effected, and whether he has become proficient
enough in his manipulation of it to be absolutely dependable
in time of emergency. No amateur should attempt
a flight alone, until he has thoroughly mastered
the steering and plane control. If the services and advice of an
experienced aviator are not to be had the
novice should mount his machine on some suitable supports
so it will be well clear of the ground, and, getting
into the operator's seat, proceed to make himself well
acquainted with the operation of the steering wheel and

Some Things to Be Learned.

He will soon learn that certain movements of the
steering gear produce certain effects on the rudders. If,
for instance, his machine is equipped with a steering
wheel, he will find that turning the wheel to the right
turns the aeroplane in the same direction, because the
tiller is brought around to the left. In the same way
he will learn that a given movement of the lever throws
the forward edge of the main plane upward, and that the
machine, getting the impetus of the wind under the concave
surfaces of the planes, will ascend. In the same
way it will quickly become apparent to him that an opposite
movement of the lever will produce an opposite
effect--the forward edges of the planes will be lowered,
the air will be "spilled" out to the rear, and the machine
will descend.

The time expended in these preliminary lessons will
be well spent. It would be an act of folly to attempt to
actually sail the craft without them.



It is a mistaken idea that flying machines must be
operated at extreme altitudes. True, under the impetus
of handsome prizes, and the incentive to advance scientific
knowledge, professional aviators have ascended to
considerable heights, flights at from 500 to 1,500 feet being
now common with such experts as Farman, Bleriot,
Latham, Paulhan, Wright and Curtiss. The altitude
record at this time is about 4,165 feet, held by Paulhan.

One of the instructions given by experienced aviators
to pupils, and for which they insist upon implicit obeyance, is:
"If your machine gets more than 30 feet high,
or comes closer to the ground than 6 feet, descend at
once." Such men as Wright and Curtiss will not tolerate
a violation of this rule. If their instructions are
not strictly complied with they decline to give the offender
further lessons.

Why This Rule Prevails.

There is good reason for this precaution. The higher
the altitude the more rarefied (thinner) becomes the air,
and the less sustaining power it has. Consequently the
more difficult it becomes to keep in suspension a given
weight. When sailing within 30 feet of the ground sustentation
is comparatively easy and, should a fall occur,
the results are not likely to be serious. On the other
hand, sailing too near the ground is almost as objectionable
in many ways as getting up too high. If the craft
is navigated too close to the ground trees, shrubs, fences
and other obstructions are liable to be encountered.
There is also the handicap of contrary air currents
diverted by the obstructions referred to, and which will
be explained more fully further on.

How to Make a Start.

Taking it for granted that the beginner has familiarized
himself with the manipulation of the machine, and especially
the control mechanism, the next thing in order
is an actual flight. It is probable that his machine will
be equipped with a wheeled alighting gear, as the skids
used by the Wrights necessitate the use of a special
starting track. In this respect the wheeled machine is
much easier to handle so far as novices are concerned
as it may be easily rolled to the trial grounds. This,
as in the case of the initial experiments, should be a
clear, reasonably level place, free from trees, fences,
rocks and similar obstructions with which there may be
danger of colliding.

The beginner will need the assistance of three men.
One of these should take his position in the rear of the
machine, and one at each end. On reaching the trial
ground the aviator takes his seat in the machine and,
while the men at the ends hold it steady the one in the rear
assists in retaining it until the operator is ready. In the
meantime the aviator has started his motor. Like the
glider the flying machine, in order to accomplish the
desired results, should be headed into the wind.

When the Machine Rises.

Under the impulse of the pushing movement, and assisted
by the motor action, the machine will gradually
rise from the ground--provided it has been properly
proportioned and put together, and everything is in working
order. This is the time when the aviator requires
a cool head, At a modest distance from the ground use
the control lever to bring the machine on a horizontal
level and overcome the tendency to rise. The exact
manipulation of this lever depends upon the method of
control adopted, and with this the aviator is supposed
to have thoroughly familiarized himself as previously
advised in Chapter XI.

It is at this juncture that the operator must act
promptly, but with the perfect composure begotten of
confidence. One of the great drawbacks in aviation by
novices is the tendency to become rattled, and this is
much more prevalent than one might suppose, even
among men who, under other conditions, are cool and
confident in their actions.

There is something in the sensation of being suddenly
lifted from the ground, and suspended in the air that is
disconcerting at the start, but this will soon wear off if
the experimenter will keep cool. A few successful flights
no matter how short they may be, will put a lot of
confidence into him.

Make Your Flights Short.

Be modest in your initial flights. Don't attempt to
match the records of experienced men who have devoted
years to mastering the details of aviation. Paulhan,
Farman, Bleriot, Wright, Curtiss, and all the rest of
them began, and practiced for years, in the manner here
described, being content to make just a little advancement
at each attempt. A flight of 150 feet, cleanly and
safely made, is better as a beginning than one of 400
yards full of bungling mishaps.

And yet these latter have their uses, provided the
operator is of a discerning mind and can take advantage
of them as object lessons. But, it is not well to invite
them. They will occur frequently enough under the
most favorable conditions, and it is best to have them
come later when the feeling of trepidation and uncertainty
as to what to do has worn off.

Above all, don't attempt to fly too high. Keep within
a reasonable distance from the ground--about 25 or 30
feet. This advice is not given solely to lessen the risk
of serious accident in case of collapse, but mainly because
it will assist to instill confidence in the operator.

It is comparatively easy to learn to swim in shallow
water, but the knowledge that one is tempting death in
deep water begets timidity.

Preserving the Equilibrium.

After learning how to start and stop, to ascend and
descend, the next thing to master is the art of preserving
equilibrium, the knack of keeping the machine perfectly
level in the air--on an "even keel," as a sailor would
say. This simile is particularly appropriate as all aviators
are in reality sailors, and much more daring ones
than those who course the seas. The latter are in craft
which are kept afloat by the buoyancy of the water,
whether in motion or otherwise and, so long as normal
conditions prevail, will not sink. Aviators sail the air
in craft in which constant motion must be maintained in
order to ensure flotation.

The man who has ridden a bicycle or motorcycle
around curves at anything like high speed, will have a
very good idea as to the principle of maintaining equilibrium
in an airship. He knows that in rounding curves
rapidly there is a marked tendency to change the direction
of the motion which will result in an upset unless
he overcomes it by an inclination of his body in an opposite
direction. This is why we see racers lean well
over when taking the curves. It simply must be done
to preserve the equilibrium and avoid a spill.

How It Works In the Air.

If the equilibrium of an airship is disturbed to an
extent which completely overcomes the center of gravity
it falls according to the location of the displacement.
If this displacement, for instance, is at either end the
apparatus falls endways; if it is to the front or rear, the
fall is in the corresponding direction.

Owing to uncertain air currents--the air is continually
shifting and eddying, especially within a hundred feet or
so of the earth--the equilibrium of an airship is almost
constantly being disturbed to some extent. Even if this
disturbance is not serious enough to bring on a fall it
interferes with the progress of the machine, and should
be overcome at once. This is one of the things connected
with aerial navigation which calls for prompt,
intelligent action.

Frequently, when the displacement is very slight, it
may be overcome, and the craft immediately righted by
a mere shifting of the operator's body. Take, for illustration,
a case in which the extreme right end of the
machine becomes lowered a trifle from the normal level.
It is possible to bring it back into proper position by
leaning over to the left far enough to shift the weight
to the counter-balancing point. The same holds good as
to minor front or rear displacements.

When Planes Must Be Used.

There are other displacements, however, and these are
the most frequent, which can be only overcome by manipulation of
the stabilizing planes. The method of procedure
depends upon the form of machine in use. The
Wright machine, as previously explained, is equipped
with plane ends which are so contrived as to admit of
their being warped (position changed) by means of the
lever control. These flexible tip planes move simultaneously,
but in opposite directions. As those on one end
rise, those on the other end fall below the level of the
main plane. By this means air is displaced at one point,
and an increased amount secured in another.

This may seem like a complicated system, but its
workings are simple when once understood. It is by
the manipulation or warping of these flexible tips that
transverse stability is maintained, and any tendency to
displacement endways is overcome. Longitudinal stability
is governed by means of the front rudder.

Stabilizing planes of some form are a feature, and a
necessary feature, on all flying machines, but the methods
of application and manipulation vary according to the
individual ideas of the inventors. They all tend, however,
toward the same end--the keeping of the machine
perfectly level when being navigated in the air.

When to Make a Flight.

A beginner should never attempt to make a flight
when a strong wind is blowing. The fiercer the wind,
the more likely it is to be gusty and uncertain, and the
more difficult it will be to control the machine. Even
the most experienced and daring of aviators find there
is a limit to wind speed against which they dare not
compete. This is not because they lack courage, but
have the sense to realize that it would be silly and useless.

The novice will find a comparatively still day, or one
when the wind is blowing at not to exceed 15 miles an
hour, the best for his experiments. The machine will be
more easily controlled, the trip will be safer, and also
cheaper as the consumption of fuel increases with the
speed of the wind against which the aeroplane is forced.



As a general proposition it takes much more power to
propel an airship a given number of miles in a certain
time than it does an automobile carrying a far heavier
load. Automobiles with a gross load of 4,000 pounds,
and equipped with engines of 30 horsepower, have travelled
considerable distances at the rate of 50 miles an
hour. This is an equivalent of about 134 pounds per
horsepower. For an average modern flying machine,
with a total load, machine and passengers, of 1,200
pounds, and equipped with a 50-horsepower engine, 50
miles an hour is the maximum. Here we have the equivalent
of exactly 24 pounds per horsepower. Why this
great difference?

No less an authority than Mr. Octave Chanute answers
the question in a plain, easily understood manner. He

"In the case of an automobile the ground furnishes a
stable support; in the case of a flying machine the engine
must furnish the support and also velocity by which the
apparatus is sustained in the air."

Pressure of the Wind.

Air pressure is a big factor in the matter of aeroplane
horsepower. Allowing that a dead calm exists, a body
moving in the atmosphere creates more or less resistance.
The faster it moves, the greater is this resistance.
Moving at the rate of 60 miles an hour the resistance,
or wind pressure, is approximately 50 pounds to the
square foot of surface presented. If the moving object
is advancing at a right angle to the wind the following
table will give the horsepower effect of the resistance
per square foot of surface at various speeds.

Horse Power
Miles per Hour per sq. foot
10 0.013
15 0 044
20 0.105
25 0.205
30 0.354
40 0.84
50 1.64
60 2.83
80 6.72
100 13.12

While the pressure per square foot at 60 miles an hour,
is only 1.64 horsepower, at 100 miles, less than double
the speed, it has increased to 13.12 horsepower, or exactly
eight times as much. In other words the pressure
of the wind increases with the square of the velocity.
Wind at 10 miles an hour has four times more pressure
than wind at 5 miles an hour.

How to Determine Upon Power.

This element of air resistance must be taken into consideration
in determining the engine horsepower required.
When the machine is under headway sufficient
to raise it from the ground (about 20 miles an hour),
each square foot of surface resistance, will require nearly
nine-tenths of a horsepower to overcome the wind pressure,
and propel the machine through the air. As
shown in the table the ratio of power required increases
rapidly as the speed increases until at 60 miles an hour
approximately 3 horsepower is needed.

In a machine like the Curtiss the area of wind-exposed
surface is about 15 square feet. On the basis of this
resistance moving the machine at 40 miles an hour would
require 12 horsepower. This computation covers only
the machine's power to overcome resistance. It does
not cover the power exerted in propelling the machine
forward after the air pressure is overcome. To meet
this important requirement Mr. Curtiss finds it necessary
to use a 50-horsepower engine. Of this power, as
has been already stated, 12 horsepower is consumed
in meeting the wind pressure, leaving 38 horsepower
for the purpose of making progress.

The flying machine must move faster than the air to
which it is opposed. Unless it does this there can be no
direct progress. If the two forces are equal there is no
straight-ahead advancement. Take, for sake of illustration,
a case in which an aeroplane, which has developed a
speed of 30 miles an hour, meets a wind velocity of
equal force moving in an opposite direction. What is
the result? There can be no advance because it is a
contest between two evenly matched forces. The aeroplane
stands still. The only way to get out of the difficulty
is for the operator to wait for more favorable conditions,
or bring his machine to the ground in the usual
manner by manipulation of the control system.

Take another case. An aeroplane, capable of making
50 miles an hour in a calm, is met by a head wind of 25
miles an hour. How much progress does the aeroplane
make? Obviously it is 25 miles an hour over the ground.

Put the proposition in still another way. If the wind
is blowing harder than it is possible for the engine power
to overcome, the machine will be forced backward.

Wind Pressure a Necessity.

While all this is true, the fact remains that wind
pressure, up to a certain stage, is an absolute necessity
in aerial navigation. The atmosphere itself has very
little real supporting power, especially if inactive. If
a body heavier than air is to remain afloat it must move
rapidly while in suspension.

One of the best illustrations of this is to be found in
skating over thin ice. Every school boy knows that if
he moves with speed he may skate or glide in safety
across a thin sheet of ice that would not begin to bear
his weight if he were standing still. Exactly the same
proposition obtains in the case of the flying machine.

The non-technical reason why the support of the machine
becomes easier as the speed increases is that the
sustaining power of the atmosphere increases with the
resistance, and the speed with which the object is moving
increases this resistance. With a velocity of 12 miles
an hour the weight of the machine is practically reduced
by 230 pounds. Thus, if under a condition of absolute
calm it were possible to sustain a weight of 770 pounds,
the same atmosphere would sustain a weight of 1,000
pounds moving at a speed of 12 miles an hour. This
sustaining power increases rapidly as the speed increases.
While at 12 miles the sustaining power is figured at
230 pounds, at 24 miles it is four times as great, or 920

Supporting Area of Birds.

One of the things which all producing aviators seek
to copy is the motive power of birds, particularly in their
relation to the area of support. Close investigation has
established the fact that the larger the bird the less is
the relative area of support required to secure a given
result. This is shown in the following table:

Weight Surface Horse area
Bird in lbs. in sq. feet power per lb.
Pigeon 1.00 0.7 0.012 0.7
Wild Goose 9.00 2.65 0.026 0.2833
Buzzard 5.00 5.03 0.015 1.06
Condor 17.00 9.85 0.043 0.57

So far as known the condor is the largest of modern
birds. It has a wing stretch of 10 feet from tip to tip, a
supporting area of about 10 square feet, and weighs 17
pounds. It. is capable of exerting perhaps 1-30 horsepower.
(These figures are, of course, approximate.)
Comparing the condor with the buzzard with a wing
stretch of 6 feet, supporting area of 5 square feet, and a
little over 1-100 horsepower, it may be seen that, broadly
speaking, the larger the bird the less surface area (relatively)
is needed for its support in the air.

Comparison With Aeroplanes.

If we compare the bird figures with those made possible
by the development of the aeroplane it will be
readily seen that man has made a wonderful advance in
imitating the results produced by nature. Here are the

Weight Surface Horse area
Machine in lbs. in sq. feet power per lb.
Santos-Dumont . . 350 110.00 30 0.314
Bleriot . . . . . 700 150.00 25 0.214
Antoinette. . . . 1,200 538.00 50 0.448
Curtiss . . . . . 700 258.00 60 0.368
Wright. . . . .[4]1,100 538.00 25 0.489
Farman. . . . . . 1,200 430.00 50 0.358
Voisin. . . . . . 1,200 538.00 50 0.448

[4] The Wrights' new machine weighs only 900 pounds.

While the average supporting surface is in favor of
the aeroplane, this is more than overbalanced by the
greater amount of horsepower required for the weight
lifted. The average supporting surface in birds is about
three-quarters of a square foot per pound. In the average
aeroplane it is about one-half square foot per pound.
On the other hand the average aeroplane has a lifting
capacity of 24 pounds per horsepower, while the buzzard,
for instance, lifts 5 pounds with 15-100 of a horsepower.
If the Wright machine--which has a lifting power of 50
pounds per horsepower--should be alone considered the
showing would be much more favorable to the aeroplane,
but it would not be a fair comparison.

More Surface, Less Power.

Broadly speaking, the larger the supporting area the
less will be the power required. Wright, by the use of
538 square feet of supporting surface, gets along with an
engine of 25 horsepower. Curtiss, who uses only 258
square feet of surface, finds an engine of 50 horsepower
is needed. Other things, such as frame, etc., being equal,
it stands to reason that a reduction in the area of
supporting surface will correspondingly reduce the weight
of the machine. Thus we have the Curtiss machine with
its 258 square feet of surface, weighing only 600 pounds
(without operator), but requiring double the horsepower
of the Wright machine with 538 square feet of surface
and weighing 1,100 pounds. This demonstrates in a
forceful way the proposition that the larger the surface
the less power will be needed.

But there is a limit, on account of its bulk and
awkwardness in handling, beyond which the surface area
cannot be enlarged. Otherwise it might be possible to
equip and operate aeroplanes satisfactorily with engines
of 15 horsepower, or even less.

The Fuel Consumption Problem.

Fuel consumption is a prime factor in the production
of engine power. The veriest mechanical tyro knows in
a general way that the more power is secured the more
fuel must be consumed, allowing that there is no difference
in the power-producing qualities of the material
used. But few of us understand just what the ratio of
increase is, or how it is caused. This proposition is one
of keen interest in connection with aviation.

Let us cite a problem which will illustrate the point
quoted: Allowing that it takes a given amount of gasolene
to propel a flying machine a given distance, half the
way with the wind, and half against it, the wind blowing
at one-half the speed of the machine, what will be
the increase in fuel consumption?

Increase of Thirty Per Cent.

On the face of it there would seem to be no call for
an increase as the resistance met when going against the
wind is apparently offset by the propulsive force of the
wind when the machine is travelling with it. This, however,
is called faulty reasoning. The increase in fuel
consumption, as figured by Mr. F. W. Lanchester, of the
Royal Society of Arts, will be fully 30 per cent over
the amount required for a similar operation of the machine
in still air. If the journey should be made at right
angles to the wind under the same conditions the increase
would be 15 per cent.

In other words Mr. Lanchester maintains that the work
done by the motor in making headway against the wind
for a certain distance calls for more engine energy, and
consequently more fuel by 30 per cent, than is saved by
the helping force of the wind on the return journey.



One of the first difficulties which the novice will
encounter is the uncertainty of the wind currents. With a
low velocity the wind, some distance away from the
ground, is ordinarily steady. As the velocity increases,
however, the wind generally becomes gusty and fitful
in its action. This, it should be remembered, does not
refer to the velocity of the machine, but to that of the
air itself.

In this connection Mr. Arthur T. Atherholt, president
of the Aero Club of Pennsylvania, in addressing the
Boston Society of Scientific Research, said:

"Probably the whirlpools of Niagara contain no more
erratic currents than the strata of air which is now immediately
above us, a fact hard to realize on account
of its invisibility."

Changes In Wind Currents.

While Mr. Atherholt's experience has been mainly
with balloons it is all the more valuable on this account,
as the balloons were at the mercy of the wind and their
varying directions afforded an indisputable guide as to
the changing course of the air currents. In speaking of
this he said:

"In the many trips taken, varying in distance traversed
from twenty-five to 900 miles, it was never possible
except in one instance to maintain a straight course.
These uncertain currents were most noticeable in the
Gordon-Bennett race from St. Louis in 1907. Of the
nine aerostats competing in that event, eight covered a
more or less direct course due east and southeast, whereas
the writer, with Major Henry B. Hersey, first started
northwest, then north, northeast, east, east by south, and
when over the center of Lake Erie were again blown
northwest notwithstanding that more favorable winds
were sought for at altitudes varying from 100 to 3,000
meters, necessitating a finish in Canada nearly northeast
of the starting point.

"These nine balloons, making landings extending from
Lake Ontario, Canada, to Virginia, all started from one
point within the same hour.

"The single exception to these roving currents occurred
on October 21st, of last year (1909) when, starting
from Philadelphia, the wind shifted more than eight
degrees, the greatest variation being at the lowest altitudes,
yet at no time was a height of over a mile reached.

"Throughout the entire day the sky was overcast, with
a thermometer varying from fifty-seven degrees at 300
feet to forty-four degrees, Fahrenheit at 5,000 feet, at
which altitude the wind had a velocity of 43 miles an
hour, in clouds of a cirro-cumulus nature, a landing finally
being made near Tannersville, New York, in the
Catskill mountains, after a voyage of five and one-half

"I have no knowledge of a recorded trip of this distance
and duration, maintained in practically a straight
line from start to finish."

This wind disturbance is more noticeable and more
difficult to contend with in a balloon than in a flying
machine, owing to the bulk and unwieldy character of
the former. At the same time it is not conducive to
pleasant, safe or satisfactory sky-sailing in an aeroplane.
This is not stated with the purpose of discouraging
aviation, but merely that the operator may know what to
expect and be prepared to meet it.

Not only does the wind change its horizontal course
abruptly and without notice, but it also shifts in a vertical
direction, one second blowing up, and another
down. No man has as yet fathomed the why and wherefore
of this erratic action; it is only known that it exists.

The most stable currents will be found from 50 to 100
feet from the earth, provided the wind is not diverted
by such objects as trees, rocks, etc. That there are
equally stable currents higher up is true, but they are
generally to be found at excessive altitudes.

How a Bird Meets Currents.

Observe a bird in action on a windy day and you will
find it continually changing the position of its wings.
This is done to meet the varying gusts and eddies of the
air so that sustentation may be maintained and headway
made. One second the bird is bending its wings, altering
the angle of incidence; the next it is lifting or depressing
one wing at a time. Still again it will extend
one wing tip in advance of the other, or be spreading or
folding, lowering or raising its tail.

All these motions have a meaning, a purpose. They
assist the bird in preserving its equilibrium. Without
them the bird would be just as helpless in the air as a
human being and could not remain afloat.

When the wind is still, or comparatively so, a bird,
having secured the desired altitude by flight at an angle,
may sail or soar with no wing action beyond an occasional
stroke when it desires to advance. But, in a
gusty, uncertain wind it must use its wings or alight

Trying to Imitate the Bird.

Writing in _Fly_, Mr. William E. White says:

"The bird's flight suggests a number of ways in which
the equilibrium of a mechanical bird may be controlled.
Each of these methods of control may be effected by
several different forms of mechanism.

"Placing the two wings of an aeroplane at an angle of
three to five degrees to each other is perhaps the oldest
way of securing lateral balance. This way readily occurs
to anyone who watches a sea gull soaring. The
theory of the dihedral angle is that when one wing is
lifted by a gust of wind, the air is spilled from under it;
while the other wing, being correspondingly depressed,
presents a greater resistance to the gust and is lifted
restoring the balance. A fixed angle of three to five degrees,
however, will only be sufficient for very light puffs
of wind and to mount the wings so that the whole wing
may be moved to change the dihedral angle presents
mechanical difficulties which would be better avoided.

"The objection of mechanical impracticability applies
to any plan to preserve the balance by shifting weight
or ballast. The center of gravity should be lower than
the center of the supporting surfaces, but cannot be
made much lower. It is a common mistake to assume
that complete stability will be secured by hanging the
center of gravity very low on the principle of the
parachute. An aeroplane depends upon rapid horizontal motion for
its support, and if the center of gravity be far
below the center of support, every change of speed or
wind pressure will cause the machine to turn about its
center of gravity, pitching forward and backward dangerously.

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.



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

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

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.



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

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

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