Flying Machines: Construction and Operation

Part 3 out of 4

of these patents have been started, and
others are threatened. What effect these actions will
have in deterring aviators in general from proceeding
with their experiments remains to be seen.

In the meantime the four men named--Curtiss, Voisin,
Bleriot and Farman--are going ahead regardless of
consequences, and the inventive genius of each is so strong
that it is reasonable to expect some remarkable developments
in the near future.

Smallest of Flying Machines.

To Santos Dumont must be given the credit of producing
the smallest practical flying machine yet constructed.
True, he has done nothing remarkable with it
in the line of speed, but he has demonstrated the fact
that a large supporting surface is not an essential feature.

This machine is named "La Demoiselle." It is a monoplane
of the dihedral type, with a main plane on each
side of the center. These main planes are of 18 foot
spread, and nearly 6 1/2 feet in depth, giving approximately
115 feet of surface area. The total weight is 242 pounds,
which is 358 pounds less than any other machine which
has been successfully used. The total depth from front
to rear is 26 feet.

The framework is of bamboo, strengthened and held
taut with wire guys.

Have One Rule in Mind.

In this struggle for mastery in flying machine efficiency
all the contestants keep one rule in mind, and this
is:

"The carrying capacity of an aeroplane is governed
by the peripheral curve of its carrying surfaces, plus the
speed; and the speed is governed by the thrust of the
propellers, less the 'head-on' resistance."

Their ideas as to the proper means of approaching
the proposition may, and undoubtedly are, at variance,
but the one rule in solving the problem of obtaining the
greatest carrying capacity combined with the greatest
speed, obtains in all instances.

CHAPTER XVII.

SOME OF THE NEW DESIGNS.

Spurred on by the success attained by the more experienced
and better known aviators numerous inventors
of lesser fame are almost daily producing practical flying
machines varying radically in construction from
those now in general use.

One of these comparatively new designs is the Van
Anden biplane, made by Frank Van Anden of Islip,
Long Island, a member of the New York Aeronautic
Society. While his machine is wholly experimental,
many successful short flights were made with it last fall
(1909). One flight, made October 19th, 1909, is of particular
interest as showing the practicability of an automatic
stabilizing device installed by the inventor. The
machine was caught in a sudden severe gust of wind
and keeled over, but almost immediately righted itself,
thus demonstrating in a most satisfactory manner the
value of one new attachment.

Features of Van Anden Model.

In size the surfaces of the main biplane are 26 feet
in spread, and 4 feet in depth from front to rear. The
upper and lower planes are 4 feet apart. Silkolene
coated with varnish is used for the coverings. Ribs
(spruce) are curved one inch to the foot, the deepest
part of the curve (4 inches) being one foot back from the
front edge of the horizontal beam. Struts (also of
spruce, as is all the framework) are elliptical in shape.
The main beams are in three sections, nearly half round
in form, and joined by metal sleeves.

There is a two-surface horizontal rudder, 2x2x4 feet,
in front. This is pivoted at its lateral center 8 feet from
the front edge of the main planes. In the rear is another
two-surface horizontal rudder 2x2x2 1/2 feet, pivoted
in the same manner as the front one, 15 feet from the
rear edges of the main planes.

Hinged to the rear central strut of the rear rudder
is a vertical rudder 2 feet high by 3 feet in length.

The Method of Control.

In the operation of these rudders--both front and rear
--and the elevation and depression of the main planes,
the Curtiss system is employed. Pushing the steering-
wheel post outward depresses the front edges of the
planes, and brings the machine downward; pulling the
steering-wheel post inward elevates the front edges of
the planes and causes the machine to ascend.

Turning the steering wheel itself to the right swings
the tail rudder to the left, and the machine, obeying this
like a boat, turns in the same direction as the wheel
is turned. By like cause turning the wheel to the left
turns the machine to the left.

Automatic Control of Wings.

There are two wing tips, each of 6 feet spread (length)
and 2 feet from front to rear. These are hinged half
way between the main surfaces to the two outermost
rear struts. Cables run from these to an automatic
device working with power from the engine, which automatically
operates the tips with the tilting of the
machine. Normally the wing tips are held horizontal
by stiff springs introduced in the cables outside of the
device.

It was the successful working of this device which
righted the Van Anden craft when it was overturned in
the squall of October 19th, 1909. Previous to that
occurrence Mr. Van Anden had looked upon the device
as purely experimental, and had admitted that he had
grave uncertainty as to how it would operate in time of
emergency. He is now quoted as being thoroughly satisfied
with its practicability. It is this automatic device
which gives the Van Anden machine at least one distinctively
new feature.

While on this subject it will not be amiss to add that
Mr. Curtiss does not look kindly on automatic control.
"I would rather trust to my own action than that of a
machine," he says. This is undoubtedly good logic so
far as Mr. Curtiss is concerned, but all aviators are not
so cool-headed and resourceful.

Motive Power of Van Anden.

A 50-horsepower "H-F" water cooled motor drives a
laminated wood propeller 6 feet in diameter, with a 17
degree pitch at the extremities, increasing toward the
hub. The rear end of the motor is about 6 inches back
from the rear transverse beam and the engine shaft is
in a direct line with the axes of the two horizontal rudders.
An R. I. V. ball bearing carries the shaft at this
point. Flying, the motor turns at about 800 revolutions
per minute, delivering 180 pounds pull. A test of the
motor running at 1,200 showed a pull of 250 pounds on
the scales.

Still Another New Aeroplane.

Another new aeroplane is that produced by A. M.
Herring (an old-timer) and W. S. Burgess, under the
name of the Herring-Burgess. This is also equipped
with an automatic stability device for maintaining the
balance transversely. The curvature of the planes is
also laid out on new lines. That this new plan is
effective is evidenced by the fact that the machine has
been elevated to an altitude of 40 feet by using one-half
the power of the 30-horsepower motor.

The system of rudder and elevation control is very
simple. The aviator sits in front of the lower plane,
and extending his arms, grasps two supports which extend
down diagonally in front. On the under side of
these supports just beneath his fingers are the controls
which operate the vertical rudder, in the rear. Thus, if
he wishes to turn to the right, he presses the control
under the fingers of his right hand; if to the left, that
under the fingers of his left hand. The elevating rudder
is operated by the aviator's right foot, the control
being placed on a foot-rest.

Motor Is Extremely Light.

Not the least notable feature of the craft is its motor.
Although developing, under load, 30-horsepower, or that
of an ordinary automobile, it weighs, complete, hardly
100 pounds. Having occasion to move it a little distance
for inspection, Mr. Burgess picked it up and walked
off with it--cylinders, pistons, crankcase and all, even
the magneto, being attached. There are not many 30-
horsepower engines which can be so handled. Everything
about it is reduced to its lowest terms of simplicity,
and hence, of weight. A single camshaft operates
not only all of the inlet and exhaust valves, but the magneto
and gear water pump, as well. The motor is placed
directly behind the operator, and the propeller is directly
mounted on the crankshaft.

This weight of less than 100 pounds, it must be
remembered, is not for the motor alone; it includes the
entire power plant equipment.

The "thrust" of the propeller is also extraordinary,
being between 250 and 260 pounds. The force of the
wind displacement is strong enough to knock down a
good-sized boy as one youngster ascertained when he
got behind the propeller as it was being tested. He
was not only knocked down but driven for some distance
away from the machine. The propeller has four
blades which are but little wider than a lath.

Machine Built by Students.

Students at the University of Pennsylvania, headed by
Laurence J. Lesh, a protege of Octave Chanute, have
constructed a practical aeroplane of ordinary maximum
size, in which is incorporated many new ideas. The
most unique of these is to be found in the steering gear,
and the provision made for the accommodation of a
pupil while taking lessons under an experienced aviator.

Immediately back of the aviator is an extra seat and
an extra steering wheel which works in tandem style
with the front wheel. By this arrangement a beginner
may be easily and quickly taught to have perfect control
of the machine. These tandem wheels are also
handy for passengers who may wish to operate the car
independently of one another, it being understood, of
course, that there will be no conflict of action.

Frame Size and Engine Power.

The frame has 36 feet spread and measures 35 feet
from the front edge to the end of the tail in the rear. It
is equipped with two rear propellers operated by a Ramsey
8-cylinder motor of 50 horsepower, placed horizontally
across the lower plane, with the crank shaft running
clear through the engine.

The "Pennsylvania I" is the first two-propeller biplane
chainless car, this scheme having been adopted in order
to avoid the crossing of chains. The lateral control is
by a new invention by Octave Chanute and Laurence J.
Lesh, for which Lesh is now applying for a patent. The
device was worked out before the Wright brothers' suit
was begun, and is said to be superior to the Wright
warping or the Curtiss ailerons. The landing device is
also new in design. This aeroplane will weigh about
1,500 pounds, and will carry fuel for a flight of 150 miles,
and it is expected to attain a speed of at least 45 miles
an hour.

There are others, lots of them, too numerous in fact
to admit of mention in a book of this size.

CHAPTER XVIII.

DEMAND FOR FLYING MACHINES.

As a commercial proposition the manufacture and sale
of motor-equipped aeroplanes is making much more
rapid advance than at first obtained in the similar
handling of the automobile. Great, and even phenomenal,
as was the commercial development of the motor
car, that of the flying machine is even greater. This is
a startling statement, but it is fully warranted by the
facts.

It is barely more than a year ago (1909) that attention
was seriously attracted to the motor-equipped aeroplane
as a vehicle possible of manipulation by others
than professional aviators. Up to that time such actual
flights as were made were almost exclusively with the
sole purpose of demonstrating the practicability of the
machine, and the merits of the ideas as to shape, engine
power, etc., of the various producers.

Results of Bleriot's Daring.

It was not until Bleriot flew across the straits of
Dover on July 25th, 1909, that the general public awoke
to a full realization of the fact that it was possible for
others than professional aviators to indulge in aviation.
Bleriot's feat was accepted as proof that at last an
absolutely new means of sport, pleasure and research,
had been practically developed, and was within the
reach of all who had the inclination, nerve and financial
means to adopt it.

From this event may be dated the birth of the modern
flying machine into the world of business. The automobile
was taken up by the general public from the
very start because it was a proposition comparatively
easy of demonstration. There was nothing mysterious
or uncanny in the fact that a wheeled vehicle could be
propelled on solid, substantial roads by means of engine
power. And yet it took (comparatively speaking) a long
time to really popularize the motor car.

Wonderful Results in a Year.

Men of large financial means engaged in the manufacture
of automobiles, and expended fortunes in attracting
public attention to them through the medium of
advertisements, speed and road contests, etc. By these
means a mammoth business has been built up, but bringing
this business to its present proportions required
years of patient industry and indomitable pluck.

At this writing, less than a year from the day when
Bleriot crossed the channel, the actual sales of flying
machines outnumber the actual sales of automobiles in
the first year of their commercial development. This
may appear incredible, but it is a fact as statistics will
show.

In this connection we should take into consideration
the fact that up to a year ago there was no serious intention
of putting flying machines on the market; no
preparations had been made to produce them on a commercial
scale; no money had been expended in advertisements
with a view to selling them.

Some of the Actual Results.

Today flying machines are being produced on a commercial
basis, and there is a big demand for them. The
people making them are overcrowded with orders. Some
of the producers are already making arrangements to
enlarge their plants and advertise their product for sale
the same as is being done with automobiles, while a
number of flying machine motor makers are already
promoting the sale of their wares in this way.

Here are a few actual figures of flying machine sales
made by the more prominent producers since July 25th,
1909.

Santos Dumont, 90 machines; Bleriot, 200; Farman,
130; Clemenceau-Wright, 80; Voisin, 100; Antoinette,
100. Many of these orders have been filled by delivery
of the machines, and in others the construction work
is under way.

The foregoing are all of foreign make. In this country
Curtiss and the Wrights are engaged in similar
work, but no actual figures of their output are obtainable.

Larger Plants Are Necessary.

And this situation exists despite the fact that none of
the producers are really equipped with adequate plants
for turning out their machines on a modern, business-
like basis. The demand was so sudden and unexpected
that it found them poorly prepared to meet it. This,
however, is now being remedied by the erection of special
plants, the enlargement of others, and the introduction
of new machinery and other labor-saving conveniences.

Companies, with large capitalization, to engage in the
exclusive production of airships are being organized in
many parts of the world. One notable instance of this
nature is worth quoting as illustrative of the manner
in which the production of flying machines is being
commercialized. This is the formation at Frankfort,
Germany, of the Flugmaschine Wright, G. m. b. H., with
a capital of $119,000, the Krupps, of Essen, being interested.

Prices at Which Machines Sell.

This wonderful demand from the public has come
notwithstanding the fact that the machines, owing to lack
of facilities for wholesale production, are far from being
cheap. Such definite quotations as are made are
on the following basis:

Santos Dumont--List price $1,000, but owing to the
rush of orders agents are readily getting from $1,300 to
$1,500. This is the smallest machine made.

Bleriot--List price $2,500. This is for the cross-
channel type, with Anzani motor.

Antoinette--List price from $4,000 to $5,000, according
to size.

Wright--List price $5,600.

Curtiss--List price $5,000.

There is, however, no stability in prices as purchasers
are almost invariably ready to pay a considerable premium
to facilitate delivery.

The motor is the most expensive part of the flying
machine. Motor prices range from $500 to $2,000, this
latter amount being asked for the Curtiss engine.

Systematic Instruction of Amateurs.

In addition to the production of flying machines many
of the experienced aviators are making a business of
the instruction of amateurs. Curtiss and the Wrights
in this country have a number of pupils, as have also
the prominent foreigners. Schools of instruction are
being opened in various parts of the world, not alone as
private money-making ventures, but in connection with
public educational institutions. One of these latter is
to be found at the University of Barcelona, Spain.

The flying machine agent, the man who handles the
machines on a commission, has also become a known
quantity, and will soon be as numerous as his brother
of the automobile. The sign "John Bird, agent for
Skimmer's Flying Machine," is no longer a curiosity.

Yes, the Airship Is Here.

From all of which we may well infer that the flying
machine in practical form has arrived, and that it is
here to stay. It is no exaggeration to say that the time
is close at hand when people will keep flying machines
just as they now keep automobiles, and that pleasure
jaunts will be fully as numerous and popular. With
the important item of practicability fully demonstrated,
"Come, take a trip in my airship," will have more real
significance than now attaches to the vapid warblings
of the vaudeville vocalist.

As a further evidence that the airship is really here,
and that its presence is recognized in a business way,
the action of life and accident insurance companies is
interesting. Some of them are reconstructing their policies
so as to include a special waiver of insurance by
aviators. Anything which compels these great corporations
to modify their policies cannot be looked upon as
a mere curiosity or toy.

It is some consolation to know that the movement in
this direction is not thus far widespread. Moreover it
is more than probable that the competition for business
will eventually induce the companies to act more
liberally toward aviators, especially as the art of aviation
advances.

CHAPTER XIX.

LAW OF THE AIRSHIP.

Successful aviation has evoked some peculiar things
in the way of legal action and interpretation of the law.

It is well understood that a man's property cannot
be used without his consent. This is an old established
principle in common law which holds good today.

The limits of a man's property lines, however, have
not been so well understood by laymen. According to
eminent legal authorities such as Blackstone, Littleton
and Coke, the "fathers of the law," the owner of realty
also holds title above and below the surface, and this
theory is generally accepted without question by the
courts.

Rights of Property Owners.

In other words the owner of realty also owns the sky
above it without limit as to distance. He can dig as
deep into his land, or go as high into the air as he desires,
provided he does not trespass upon or injure similar
rights of others.

The owner of realty may resist by force, all other
means having failed, any trespass upon, or invasion of
his property. Other people, for instance, may not enter
upon it, or over or under it, without his express permission
and consent. There is only one exception, and
this is in the case of public utility corporations such as
railways which, under the law of eminent domain, may
condemn a right of way across the property of an obstinate owner
who declines to accept a fair price for the
privilege.

Privilege Sharply Confined.

The law of eminent domain may be taken advantage
of only by corporations which are engaged in serving
the public. It is based upon the principle that the
advancement and improvement of a community is of more
importance and carries with it more rights than the
interests of the individual owner. But even in cases where
the right of eminent domain is exercised there can be no
confiscation of the individual's property.

Exercising the right of eminent domain is merely
obtaining by public purchase what is held to be essential
to the public good, and which cannot be secured by private
purchase. When eminent domain proceedings are
resorted to the court appoints appraisers who determine
upon the value of the property wanted, and this value
(in money) is paid to the owner.

How It Affects Aviation.

It should be kept in mind that this privilege of the
"right of eminent domain" is accorded only to corporations
which are engaged in serving the public. Individuals
cannot take advantage of it. Thus far all aviation
has been conducted by individuals; there are no flying
machine or airship corporations regularly engaged in the
transportation of passengers, mails or freight.

This leads up to the question "What would happen if
realty owners generally, or in any considerable numbers.
should prohibit the navigation of the air above their
holdings?" It is idle to say such a possibility is ridiculous--
it is already an actuality in a few individual instances.

One property owner in New Jersey, a justice of the
peace, maintains a large sign on the roof of his house
warning aviators that they must not trespass upon his
domain. That he is acting well within his rights in doing
this is conceded by legal authorities.

Hard to Catch Offenders.

But, suppose the alleged trespass is committed, what
is the property owner going to do about it? He must
first catch the trespasser and this would be a pretty hard
job. He certainly could not overtake him, unless he
kept a racing aeroplane for this special purpose. It
would be equally difficult to indentify the offender after
the offense had been committed, even if he were located,
as aeroplanes carry no license numbers.

Allowing that the offender should be caught the only
recourse of the realty owner is an action for damages.
He may prevent the commission of the offense by force
if necessary, but after it is committed he can only sue
for damages. And in doing this he would have a lot of
trouble.

Points to Be Proven.

One of the first things the plaintiff would be called
upon to prove would be the elevation of the machine.
If it were reasonably close to the ground there would,
of course, be grave risk of damage to fences, shrubbery,
and other property, and the court would be justified in
holding it to be a nuisance that should be suppressed.

If, on the other hand; the machine was well up in the
air, but going slowly, or hovering over the plaintiff's
property, the court might be inclined to rule that it
could not possibly be a nuisance, but right here the court
would be in serious embarrassment. By deciding that
it was not a nuisance he would virtually override the
law against invasion of a man's property without his
consent regardless of the nature of the invasion. By
the same decision he would also say in effect that, if one
flying machine could do this a dozen or more would
have equal right to do the same thing. While one machine
hovering over a certain piece of property may be
no actual nuisance a dozen or more in the same position
could hardly be excused.

Difficult to Fix Damages.

Such a condition would tend to greatly increase the
risk of accident, either through collision, or by the
carelessness
of the aviators in dropping articles which might
cause damages to the people or property below. In
such a case it would undoubtedly be a nuisance, and
in addition to a fine, the offender would also be liable
for the damages.

Taking it for granted that no actual damage is done,
and the owner merely sues on account of the invasion
of his property, how is the amount of compensation to
be fixed upon? The owner has lost nothing; no part of
his possessions has been taken away; nothing has been
injured or destroyed; everything is left in exactly the
same condition as before the invasion. And yet, if the
law is strictly interpreted, the offender is liable.

Right of Way for Airships.

Somebody has suggested the organization of flying-
machine corporations as common carriers, which would
give them the right of eminent domain with power to
condemn a right of way. But what would they condemn?
There is nothing tangible in the air. Railways
in condemning a right of way specify tangible property
(realty) within certain limits. How would an aviator
designate any particular right of way through the air
a certain number of feet in width, and a certain distance
from the ground?

And yet, should the higher courts hold to the letter
of the law and decide that aviators have no right to
navigate their craft over private property, something
will have to be done to get them out of the dilemma, as
aviation is too far advanced to be discarded. Fortunately
there is little prospect of any widespread antagonism
among property owners so long as aviators refrain
from making nuisances of themselves.

Possible Solution Offered.

One possible solution is offered and that is to confine
the path of airships to the public highways so that nobody's
property rights would be invaded. In addition,
as a matter of promoting safety for both operators and
those who may happen to be beneath the airships as
they pass over a course, adoption of the French rules
are suggested. These are as follows:

Aeroplanes, when passing, must keep to the right, and
pass at a distance of at least 150 feet. They are free
from this rule when flying at altitudes of more than 100
feet. Every machine when flying at night or during
foggy weather must carry a green light on the right,
and a red light on the left, and a white headlight on the
front.

These are sensible rules, but may be improved upon
by the addition of a signal system of some kind, either
horn, whistle or bell.

Responsibility of Aviators.

Mr. Jay Carver Bossard, in recent numbers of _Fly_,
brings out some curious and interesting legal points in
connection with aviation, among which are the following:

"Private parties who possess aerial craft, and desire
to operate the same in aerial territory other than their
own, must obtain from land owners special permission
to do so, such permission to be granted only by agreement,
founded upon a valid consideration. Otherwise,
passing over another's land will in each instance amount
to a trespass.

"Leaving this highly technical side of the question,
let us turn to another view: the criminal and tort liability
of owners and operators to airship passengers. If
A invites B to make an ascension with him in his machine,
and B, knowing that A is merely an enthusiastic
amateur and far from being an expert, accepts and is
through A's innocent negligence injured, he has no
grounds for recovery. But if A contracts with B, to
transport him from one place to another, for a consideration,
and B is injured by the poor piloting of A,
A would be liable to B for damages which would result.
Now in order to safeguard such people as B, curious to
the point of recklessness, the law will have to require
all airship operators to have a license, and to secure
this license airship pilots will have to meet certain
requirements. Here again is a question. Who is going
to say whether an applicant is competent to pilot a balloon
or airship?

Fine for an Aeronaut.

"An aeroplane while maneuvering is suddenly caught
by a treacherous gale and swept to the ground. A crowd
of people hasten over to see if the aeronaut is injured,
and in doing so trample over Tax-payer Smith's garden,
much to the detriment of his growing vegetables and
flowers. Who is liable for the damages? Queer as it
may seem, a case very similar to this was decided in
1823, in the New York supreme court, and it was held
that the aeronaut was liable upon the following grounds:
'To render one man liable in trespass for the acts of
others, it must appear either that they acted in concert,
or that the act of the one, ordinarily and naturally produced
the acts of the others, Ascending in a balloon is
not an unlawful act, but it is certain that the aeronaut
has no control over its motion horizontally, but is at
the sport of the wind, and is to descend when and how
he can. His reaching the earth is a matter of hazard.
If his descent would according to the circumstances
draw a crowd of people around him, either out of curiosity,
or for the purpose of rescuing him from a perilous
situation, all this he ought to have foreseen, and must be
responsible for.'

Air Not Really Free.

"The general belief among people is, that the air is
free. Not only free to breathe and enjoy, but free to
travel in, and that no one has any definite jurisdiction
over, or in any part of it. Now suppose this were made a
legal doctrine. Would a murder perpetrated above the
clouds have to go unpunished? Undoubtedly. For felonies
committed upon the high seas ample provision is
made for their punishment, but new provisions will have
to be made for crimes committed in the air.

Relations of Owner and Employee.

"It is a general rule of law that a master is bound to
provide reasonably safe tools, appliances and machines
for his servant. How this rule is going to be applied
in cases of aeroplanes, remains to be seen. The aeroplane
owner who hires a professional aeronaut, that is,
one who has qualified as an expert, owes him very little
legal duty to supply him with a perfect aeroplane. The
expert is supposed to know as much regarding the machine
as the owner, if not more, and his acceptance of
his position relieves the owner from liability. When
the owner hires an amateur aeronaut to run the aeroplane, and
teaches him how to manipulate it, even though
the prescribed manner of manipulation will make flight
safe, nevertheless if the machine is visibly defective, or
known to be so, any injury which results to the aeronaut
the owner is liable for.

As to Aeroplane Contracts.

"At the present time there are many orders being
placed with aeroplane manufacturing companies. There
are some unique questions to be raised here under the
law of contract. It is an elementary principle of law
that no one can be compelled to complete a contract
which in itself is impossible to perform. For instance,
a contract to row a boat across the Atlantic in two
weeks, for a consideration, could never be enforced because
it is within judicial knowledge that such an undertaking
is beyond human power. Again, contracts formed
for the doing of acts contrary to nature are never
enforcible, and here is where our difficulty comes in. Is
it possible to build a machine or species of craft which
will transport a person or goods through the air? The
courts know that balloons are practical; that is, they
know that a bag filled with gas has a lifting power and
can move through the air at an appreciable height.
Therefore, a contract to transport a person in such manner
is a good contract, and the conditions being favorable
could undoubtedly be enforced. But the passengers'
right of action for injury would be very limited.

No Redress for Purchasers.

"In the case of giving warranties on aeroplanes, we
have yet to see just what a court is going to say. It is
easy enough for a manufacturer to guarantee to build a
machine of certain dimensions and according to certain
specifications, but when he inserts a clause in the contract to
the effect that the machine will raise itself from
the surface of the earth, defy the laws of gravity, and
soar in the heavens at the will of the aviator, he is to
say the least contracting to perform a miracle.

"Until aeroplanes have been made and accepted as
practical, no court will force a manufacturer to turn out
a machine guaranteed to fly. So purchasers can well
remember that if their machines refuse to fly they have
no redress against the maker, for he can always say,
'The industry is still in its experimental stage.' In
contracting for an engine no builder will guarantee that
the particular engine will successfully operate the aeroplane.
In fact he could never be forced to live up to
such an agreement, should he agree to a stipulation of
that sort. The best any engine maker will guarantee
is to build an engine according to specifications."

CHAPTER XX.

SOARING FLIGHT.

By Octave Chanute.

[5]There is a wonderful performance daily exhibited in
southern climes and occasionally seen in northerly
latitudes in summer, which has never been thoroughly
explained. It is the soaring or sailing flight of certain
varieties of large birds who transport themselves on rigid,
unflapping wings in any desired direction; who in winds
of 6 to 20 miles per hour, circle, rise, advance, return and
remain aloft for hours without a beat of wing, save for
getting under way or convenience in various maneuvers.
They appear to obtain from the wind alone all the necessary
energy, even to advancing dead against that wind.
This feat is so much opposed to our general ideas of
physics that those who have not seen it sometimes deny
its actuality, and those who have only occasionally
witnessed it subsequently doubt the evidence of their own
eyes. Others, who have seen the exceptional performances,
speculate on various explanations, but the majority
give it up as a sort of "negative gravity."

[5] Aeronautics.

Soaring Power of Birds.

The writer of this paper published in the "Aeronautical
Annual" for 1896 and 1897 an article upon the sailing
flight of birds, in which he gave a list of the authors who
had described such flight or had advanced theories for
its explanation, and he passed these in review. He also
described his own observations and submitted some computations
to account for the observed facts. These computations
were correct as far as they went, but they were
scanty. It was, for instance, shown convincingly by
analysis that a gull weighing 2.188 pounds, with a total
supporting surface of 2.015 square feet, a maximum body
cross-section of 0.126 square feet and a maximum cross-
section of wing edges of 0.098 square feet, patrolling on
rigid wings (soaring) on the weather side of a steamer
and maintaining an upward angle or attitude of 5 degrees
to 7 degrees above the horizon, in a wind blowing 12.78
miles an hour, which was deflected upward 10 degrees
to 20 degrees by the side of the steamer (these all being
carefully observed facts), was perfectly sustained at its
own "relative speed" of 17.88 miles per hour and extracted
from the upward trend of the wind sufficient energy
to overcome all the resistances, this energy
amounting to 6.44 foot-pounds per second.

Great Power of Gulls.

It was shown that the same bird in flapping flight in
calm air, with an attitude or incidence of 3 degrees to 5
degrees above the horizon and a speed of 20.4 miles an
hour was well sustained and expended 5.88 foot-pounds
per second, this being at the rate of 204 pounds sustained
per horsepower. It was stated also that a gull in its observed
maneuvers, rising up from a pile head on unflapping
wings, then plunging forward against the wind and
subsequently rising higher than his starting point, must
either time his ascents and descents exactly with the
variations in wind velocities, or must meet a wind billow
rotating on a horizontal axis and come to a poise on its
crest, thus availing of an ascending trend.

But the observations failed to demonstrate that the
variations of the wind gusts and the movements of the
bird were absolutely synchronous, and it was conjectured
that the peculiar shape of the soaring wing of certain
birds, as differentiated from the flapping wing, might,
when experimented upon, hereafter account for the performance.

Mystery to be Explained.

These computations, however satisfactory they were
for the speed of winds observed, failed to account for the
observed spiral soaring of buzzards in very light winds
and the writer was compelled to confess: "Now, this
spiral soaring in steady breezes of 5 to 10 miles per hour
which are apparently horizontal, and through which the
bird maintains an average speed of about 20 miles an
hour, is the mystery to be explained. It is not accounted
for, quantitatively, by any of the theories which have
been advanced, and it is the one performance which has
led some observers to claim that it was done through
'aspiration.' i, e., that a bird acted upon by a current,
actually drew forward into that current against its exact
direction of motion."

Buzzards Soar in Dead Calm.

A still greater mystery was propounded by the few
observers who asserted that they had seen buzzards soaring
in a dead calm, maintaining their elevation and their
speed. Among these observers was Mr. E. C. Huffaker,
at one time assistant experimenter for Professor Langley.
The writer believed and said then that he must in some
way have been mistaken, yet, to satisfy himself, he paid
several visits to Mr. Huffaker, in Eastern Tennessee and
took along his anemometer. He saw quite a number of
buzzards sailing at a height of 75 to 100 feet in breezes
measuring 5 or 6 miles an hour at the surface of the
ground, and once he saw one buzzard soaring apparently
in a dead calm.

The writer was fairly baffled. The bird was not simply
gliding, utilizing gravity or acquired momentum, he was
actually circling horizontally in defiance of physics and
mathematics. It took two years and a whole series of
further observations to bring those two sciences into
accord with the facts.

Results of Close Observations.

Curiously enough the key to the performance of circling
in a light wind or a dead calm was not found
through the usual way of gathering human knowledge,
i. e., through observations and experiment. These had
failed because I did not know what to look for. The
mystery was, in fact, solved by an eclectic process of
conjecture and computation, but once these computations
indicated what observations should be made, the results
gave at once the reasons for the circling of the birds, for
their then observed attitude, and for the necessity of an
independent initial sustaining speed before soaring began.
Both Mr. Huffaker and myself verified the data
many times and I made the computations.

These observations disclosed several facts:

1st.--That winds blowing five to seventeen miles per
hour frequently had rising trends of 10 degrees to 15
degrees, and that upon occasions when there seemed to be
absolutely no wind, there was often nevertheless a local
rising of the air estimated at a rate of four to eight miles
or more per hour. This was ascertained by watching
thistledown, and rising fogs alongside of trees or hills of
known height. Everyone will readily realize that when
walking at the rate of four to eight miles an hour in a
dead calm the "relative wind" is quite inappreciable to
the senses and that such a rising air would not be noticed.

2nd.--That the buzzard, sailing in an apparently dead
horizontal calm, progressed at speeds of fifteen to eighteen
miles per hour, as measured by his shadow on the
ground. It was thought that the air was then possibly
rising 8.8 feet per second, or six miles per hour.

3rd.--That when soaring in very light winds the angle
of incidence of the buzzards was negative to the horizon
--i. e., that when seen coming toward the eye, the afternoon
light shone on the back instead of on the breast,
as would have been the case had the angle been inclined
above the horizon.

4th.--That the sailing performance only occurred after
the bird had acquired an initial velocity of at least fifteen
or eighteen miles per hour, either by industrious flapping
or by descending from a perch.

An Interesting Experiment.

5th.--That the whole resistance of a stuffed buzzard,
at a negative angle of 3 degrees in a current of air of
15.52 miles per hour, was 0.27 pounds. This test was
kindly made for the writer by Professor A. F. Zahm in
the "wind tunnel" of the Catholic University at Washington,
D. C., who, moreover, stated that the resistance
of a live bird might be less, as the dried plumage could
not be made to lie smooth.

This particular buzzard weighed in life 4.25 pounds,
the area of his wings and body was 4.57 square feet, the
maximum cross-section of his body was 0.110 square feet,
and that of his wing edges when fully extended was
0.244 square feet.

With these data, it became surprisingly easy to compute
the performance with the coefficients of Lilienthal
for various angles of incidence and to demonstrate how
this buzzard could soar horizontally in a dead horizontal
calm, provided that it was not a vertical calm, and that
the air was rising at the rate of four or six miles per
hour, the lowest observed, and quite inappreciable without
actual measuring.

Some Data on Bird Power.

The most difficult case is purposely selected. For if
we assume that the bird has previously acquired an initial
minimum speed of seventeen miles an hour (24.93
feet per second, nearly the lowest measured), and that
the air was rising vertically six miles an hour (8.80 feet
per second), then we have as the trend of the "relative
wind" encountered:

6
-- = 0.353, or the tangent of 19 degrees 26'.
17

which brings the case into the category of rising wind
effects. But the bird was observed to have a negative
angle to the horizon of about 3 degrees, as near as could be
guessed, so that his angle of incidence to the "relative
wind" was reduced to 16 degrees 26'.

The relative speed of his soaring was therefore:

Velocity = square root of (17 squared + 6 squared) = 18.03 miles
per hour.

At this speed, using the Langley co-efficient recently
practically confirmed by the accurate experiments of Mr.
Eiffel, the air pressure would be:

18.03 squared X 0.00327 = 1.063 pounds per square foot.

If we apply Lilienthal's co-efficients for an angle of
6 degrees 26', we have for the force in action:

Normal: 4.57 X 1.063 X 0.912 = 4.42 pounds.

Tangential: 4.57 X 1.063 X 0.074 = - 0.359 pounds,
which latter, being negative, is a propelling force.

Results Astonish Scientists.

Thus we have a bird weighing 4.25 pounds not only
thoroughly supported, but impelled forward by a force
of 0.359 pounds, at seventeen miles per hour, while the
experiments of Professor A. F. Zahm showed that the
resistance at 15.52 miles per hour was only 0.27 pounds,
17 squared
or 0.27 X ------- = 0.324 pounds, at seventeen miles an
15.52 squared
hour.

These are astonishing results from the data obtained,
and they lead to the inquiry whether the energy of the
rising air is sufficient to make up the losses which occur
by reason of the resistance and friction of the bird's body
and wings, which, being rounded, do not encounter air
pressures in proportion to their maximum cross-section.

We have no accurate data upon the co-efficients to apply
and estimates made by myself proved to be much
smaller than the 0.27 pounds resistance measured by
Professor Zahm, so that we will figure with the latter
as modified. As the speed is seventeen miles per hour, or
24.93 feet per second, we have for the work:

Work done, 0.324 X 24.93 = 8.07 foot pounds per second.

Endorsed by Prof. Marvin.

Corresponding energy of rising air is not sufficient at
four miles per hour. This amounts to but 2.10 foot pounds
per second, but if we assume that the air was rising at
the rate of seven miles per hour (10.26 feet per second),
at which the pressure with the Langley coefficient would
be 0.16 pounds per square foot, we have on 4.57 square
feet for energy of rising air: 4.57 X 0.16 X 10.26 = 7.50
foot pounds per second, which is seen to be still a little
too small, but well within the limits of error, in view of
the hollow shape of the bird's wings, which receive
greater pressure than the flat planes experimented upon
by Langley.

These computations were chiefly made in January,
1899, and were communicated to a few friends, who found
no fallacy in them, but thought that few aviators would
understand them if published. They were then submitted
to Professor C. F. Marvin of the Weather Bureau, who
is well known as a skillful physicist and mathematician.
He wrote that they were, theoretically, entirely sound
and quantitatively, probably, as accurate as the present
state of the measurements of wind pressures permitted.
The writer determined, however, to withhold publication
until the feat of soaring flight had been performed by
man, partly because he believed that, to ensure safety, it
would be necessary that the machine should be equipped
with a motor in order to supplement any deficiency in
wind force.

Conditions Unfavorable for Wrights.

The feat would have been attempted in 1902 by Wright
brothers if the local circumstances had been more favorable.
They were experimenting on "Kill Devil Hill,"
near Kitty Hawk, N. C. This sand hill, about 100 feet
high, is bordered by a smooth beach on the side whence
come the sea breezes, but has marshy ground at the back.
Wright brothers were apprehensive that if they rose on
the ascending current of air at the front and began to
circle like the birds, they might be carried by the
descending current past the back of the hill and land in
the marsh. Their gliding machine offered no greater
head resistance in proportion than the buzzard, and their gliding
angles of descent are practically as favorable, but
the birds performed higher up in the air than they.

Langley's Idea of Aviation.

Professor Langley said in concluding his paper upon
"The Internal Work of the Wind":

"The final application of these principles to the art of
aerodromics seems, then, to be, that while it is not likely
that the perfected aerodrome will ever be able to dispense
altogether with the ability to rely at intervals on
some internal source of power, it will not be indispensable
that this aerodrome of the future shall, in order to
go any distance--even to circumnavigate the globe without
alighting--need to carry a weight of fuel which
would enable it to perform this journey under conditions
analogous to those of a steamship, but that the fuel and
weight need only be such as to enable it to take care of
itself in exceptional moments of calm."

Now that dynamic flying machines have been evolved
and are being brought under control, it seems to be
worth while to make these computations and the succeeding
explanations known, so that some bold man will
attempt the feat of soaring like a bird. The theory
underlying the performance in a rising wind is not new,
it has been suggested by Penaud and others, but it has
attracted little attention because the exact data and the
maneuvers required were not known and the feat had
not yet been performed by a man. The puzzle has always
been to account for the observed act in very light
winds, and it is hoped that by the present selection of
the most difficult case to explain--i. e., the soaring in a
dead horizontal calm--somebody will attempt the exploit.

Requisites for Soaring Flights.

The following are deemed to be the requisites and
maneuvers to master the secrets of soaring flight:

1st--Develop a dynamic flying machine weighing
about one pound per square foot of area, with stable
equilibrium and under perfect control, capable of gliding
by gravity at angles of one in ten (5 3/4 degrees) in still air.

2nd.--Select locations where soaring birds abound and
occasions where rising trends of gentle winds are frequent
and to be relied on.

3rd.--Obtain an initial velocity of at least 25 feet per
second before attempting to soar.

4th.--So locate the center of gravity that the apparatus
shall assume a negative angle, fore and aft, of about 3 degrees.

Calculations show, however, that sufficient propelling
force may still exist at 0 degrees, but disappears entirely at
+4 degrees.

5th.--Circle like the bird. Simultaneously with the
steering, incline the apparatus to the side toward which
it is desired to turn, so that the centrifugal force shall
be balanced by the centripetal force. The amount of the
required inclination depends upon the speed and on the
radius of the circle swept over.

6th.--Rise spirally like the bird. Steer with the
horizontal rudder, so as to descend slightly when going
with the wind and to ascend when going against the
wind. The bird circles over one spot because the rising
trends of wind are generally confined to small areas or
local chimneys, as pointed out by Sir H. Maxim and
others.

7th.--Once altitude is gained, progress may be made
in any direction by gliding downward by gravity.

The bird's flying apparatus and skill are as yet infinitely
superior to those of man, but there are indications that
within a few years the latter may evolve more accurately
proportioned apparatus and obtain absolute control over
it.

It is hoped, therefore, that if there be found no radical
error in the above computations, they will carry the conviction
that soaring flight is not inaccessible to man, as
it promises great economies of motive power in favorable
localities of rising winds.

The writer will be grateful to experts who may point
out any mistake committed in data or calculations, and
will furnish additional information to any aviator who
may wish to attempt the feat of soaring.

CHAPTER XXI.

FLYING MACHINES VS. BALLOONS.

While wonderful success has attended the development
of the dirigible (steerable) balloon the most ardent
advocates of this form of aerial navigation admit that it
has serious drawbacks. Some of these may be described
as follows:

Expense and Other Items.

Great Initial Expense.--The modern dirigible balloon
costs a fortune. The Zeppelin, for instance, costs more
than $100,000 (these are official figures).

Expense of Inflation.--Gas evaporates rapidly, and a
balloon must be re-inflated, or partially re-inflated, every
time it is used. The Zeppelin holds 460,000 cubic feet
of gas which, even at $1 per thousand, would cost $460.

Difficulty of Obtaining Gas.--If a balloon suddenly
becomes deflated, by accident or atmospheric conditions,
far from a source of gas supply, it is practically worthless.
Gas must be piped to it, or the balloon carted to
the gas house--an expensive proceeding in either event.

Lack of Speed and Control.

Lack of Speed.--Under the most favorable conditions
the maximum speed of a balloon is 30 miles an hour.
Its great bulk makes the high speed attained by flying
machines impossible.

Difficulty of Control.--While the modern dirigible balloon is
readily handled in calm or light winds, its bulk
makes it difficult to control in heavy winds.

The Element of Danger.--Numerous balloons have
been destroyed by lightning and similar causes. One of
the largest of the Zeppelins was thus lost at Stuttgart
in 1908.

Some Balloon Performances.

It is only a matter of fairness to state that, under
favorable conditions, some very creditable records have
been made with modern balloons, viz:

November 23d, 1907, the French dirigible Patrie, travelled
187 miles in 6 hours and 45 minutes against a
light wind. This was a little over 28 miles an hour.

The Clement-Bayard, another French machine, sold
to the Russian government, made a trip of 125 miles at
a rate of 27 miles an hour.

Zeppelin No. 3, carrying eight passengers, and having
a total lifting capacity of 5,500 pounds of ballast in
addition to passengers, weight of equipment, etc., was
tested in October, 1906, and made 67 miles in 2 hours
and 17 minutes, about 30 miles an hour.

These are the best balloon trips on record, and show
forcefully the limitations of speed, the greatest being not
over 30 miles an hour.

Speed of Flying Machines.

Opposed to the balloon performances we have flying
machine trips (of authentic records) as follows:

Bleriot--monoplane--in 1908--52 miles an hour.

Delagrange--June 22, 1908--10 1/2 miles in 16 minutes,
approximately 42 miles an hour.

Wrights--October, 1905--the machine was then in its
infancy--24 miles in 38 minutes, approximately 44 miles
an hour. On December 31, 1908, the Wrights made 77
miles in 2 hours and 20 minutes.

Lambert, a pupil of the Wrights, and using a Wright
biplane, on October 18, 1909, covered 29.82 miles in 49
minutes and 39 seconds, being at the rate of 36 miles
an hour. This flight was made at a height of 1,312 feet.

Latham--October 21, 1909--made a short flight, about
11 minutes, in the teeth of a 40 mile gale, at Blackpool,
Eng. He used an Antoniette monoplane, and the official
report says: "This exhibition of nerve, daring and ability
is unparalled in the history of aviation."

Farman--October 20, 1909--was in the air for 1 hour,
32 min., 16 seconds, travelling 47 miles, 1,184 yards, a
duration record for England.

Paulhan--January 18, 1901--47 1/2 miles at the rate of
45 miles an hour, maintaining an altitude of from 1,000
to 2,000 feet.

Expense of Producing Gas.

Gas is indispensable in the operation of dirigible balloons,
and gas is expensive. Besides this it is not always
possible to obtain it in sufficient quantities even in large
cities, as the supply on hand is generally needed for
regular customers. Such as can be had is either water
or coal gas, neither of which is as efficient in lifting
power as hydrogen.

Hydrogen is the lightest and consequently the most
buoyant of all known gases. It is secured commercially
by treating zinc or iron with dilute sulphuric or
hydrochloric acid. The average cost may be safely placed
at $10 per 1,000 feet so that, to inflate a balloon of the
size of the Zeppelin, holding 460,000 cubic feet, would
cost $4,600.

Proportions of Materials Required.

In making hydrogen gas it is customary to allow 20
per cent for loss between the generation and the introduction
of the gas into the balloon. Thus, while the
formula calls for iron 28 times heavier than the weight
of the hydrogen required, and acid 49 times heavier, the
real quantities are 20 per cent greater. Hydrogen weighs
about 0.09 ounce to the cubic foot. Consequently if we
need say 450,000 cubic feet of gas we must have 2,531.25
pounds in weight. To produce this, allowing for the 20
percent loss, we must have 35 times its weight in iron,
or over 44 tons. Of acid it would take 60 times the
weight of the gas, or nearly 76 tons.

In Time of Emergency.

These figures are appalling, and under ordinary conditions
would be prohibitive, but there are times when
the balloon operator, unable to obtain water or coal gas,
must foot the bills. In military maneuvers, where the
field of operation is fixed, it is possible to furnish supplies
of hydrogen gas in portable cylinders, but on long
trips where sudden leakage or other cause makes descent
in an unexpected spot unavoidable, it becomes a question
of making your own hydrogen gas or deserting the balloon.
And when this occurs the balloonist is up against
another serious proposition--can he find the necessary
zinc or iron? Can he get the acid?

Balloons for Commercial Use.

Despite all this the balloon has its uses. If there is to
be such a thing as aerial navigation in a commercial
way--the carrying of freight and passengers--it will
come through the employment of such monster balloons
as Count Zeppelin is building. But even then the carrying
capacity must of necessity be limited. The latest
Zeppelin creation, a monster in size, is 450 feet long,
and 42 1/2 feet in diameter. The dimensions are such as
to make all other balloons look like pigmies; even many
ocean-going steamers are much smaller, and yet its passenger
capacity is very small. On its 36-hour flight in
May, 1909, the Zeppelin, carried only eight passengers.
The speed, however, was quite respectable, 850 miles
being covered in the 36 hours, a trifle over 23 miles an
hour. The reserve buoyancy, that is the total lifting
capacity aside from the weight of the airship and its
equipment, is estimated at three tons.

CHAPTER XXII.

PROBLEMS OF AERIAL FLIGHT.

In a lecture before the Royal Society of Arts, reported
in Engineering, F. W. Lanchester took the position that
practical flight was not the abstract question which some
apparently considered it to be, but a problem in locomotive
engineering. The flying machine was a locomotive
appliance, designed not merely to lift a weight,
but to transport it elsewhere, a fact which should be
sufficiently obvious. Nevertheless one of the leading scientific
men of the day advocated a type in which this, the
main function of the flying machine, was overlooked.
When the machine was considered as a method of transport,
the vertical screw type, or helicopter, became at
once ridiculous. It had, nevertheless, many advocates
who had some vague and ill-defined notion of subsequent
motion through the air after the weight was raised.

Helicopter Type Useless.

When efficiency of transport was demanded, the helicopter
type was entirely out of court. Almost all of
its advocates neglected the effect of the motion of the
machine through the air on the efficiency of the vertical
screws. They either assumed that the motion was
so slow as not to matter, or that a patch of still air
accompanied the machine in its flight. Only one form of this
type had any possibility of success. In this there were
two screws running on inclined axles--one on each side
of the weight to be lifted. The action of such inclined
screw was curious, and in a previous lecture he had
pointed out that it was almost exactly the same as that
of a bird's wing. In high-speed racing craft such inclined
screws were of necessity often used, but it was
at a sacrifice of their efficiency. In any case the efficiency
of the inclined-screw helicopter could not compare
with that of an aeroplane, and that type might be
dismissed from consideration so soon as efficiency became
the ruling factor of the design.

Must Compete With Locomotive.

To justify itself the aeroplane must compete, in some
regard or other, with other locomotive appliances, performing
one or more of the purposes of locomotion more
efficiently than existing systems. It would be no use
unless able to stem air currents, so that its velocity must
he greater than that of the worst winds liable to be encountered.
To illustrate the limitations imposed on the
motion of an aeroplane by wind velocity, Mr. Lanchester
gave the diagrams shown in Figs. 1 to 4. The circle
in each case was, he said, described with a radius equal
to the speed of the aeroplane in still air, from a center
placed "down-wind" from the aeroplane by an amount
equal to the velocity of the wind.

Fig. 1 therefore represented the case in which the
air was still, and in this case the aeroplane represented
by _A_ had perfect liberty of movement in any direction

In Fig. 2 the velocity of the wind was half that of the
aeroplane, and the latter could still navigate in any
direction, but its speed against the wind was only one-
third of its speed with the wind.

In Fig. 3 the velocity of the wind was equal to that
of the aeroplane, and then motion against the wind was
impossible; but it could move to any point of the
circle, but not to any point lying to the left of the tangent
_A_ _B_. Finally, when the wind had a greater
speed than the aeroplane, as in Fig. 4, the machine could
move only in directions limited by the tangents _A_ _C_
and _A_ _D_.

Matter of Fuel Consumption.

Taking the case in which the wind had a speed equal
to half that of the aeroplane, Mr. Lanchester said that
for a given journey out and home, down wind and back,
the aeroplane would require 30 per cent more fuel than
if the trip were made in still air; while if the journey
was made at right angles to the direction of the wind
the fuel needed would be 15 per cent more than in a
calm. This 30 per cent extra was quite a heavy enough
addition to the fuel; and to secure even this figure it
was necessary that the aeroplane should have a speed of
twice that of the maximum wind in which it was desired
to operate the machine. Again, as stated in the last
lecture, to insure the automatic stability of the machine
it was necessary that the aeroplane speed should be
largely in excess of that of the gusts of wind liable to
be encountered.

Eccentricities of the Wind.

There was, Mr. Lanchester said, a loose connection
between the average velocity of the wind and the maximum
speed of the gusts. When the average speed of
the wind was 40 miles per hour, that of the gusts might
be equal or more. At one moment there might be a
calm or the direction of the wind even reversed, followed,
the next moment, by a violent gust. About the same
minimum speed was desirable for security against gusts
as was demanded by other considerations. Sixty miles
an hour was the least figure desirable in an aeroplane,
and this should be exceeded as much as possible. Actually,
the Wright machine had a speed of 38 miles per
hour, while Farman's Voisin machine flew at 45 miles
per hour.

Both machines were extremely sensitive to high winds,
and the speaker, in spite of newspaper reports to the
contrary, had never seen either flown in more than a
gentle breeze. The damping out of the oscillations of
the flight path, discussed in the last lecture, increased
with the fourth power of the natural velocity of flight,
and rapid damping formed the easiest, and sometimes
the only, defense against dangerous oscillations. A
machine just stable at 35 miles per hour would have
reasonably rapid damping if its speed were increased to
60 miles per hour.

Thinks Use Is Limited.

It was, the lecturer proceeded, inconceivable that any
very extended use should be made of the aeroplane unless
the speed was much greater than that of the motor car.
It might in special cases be of service, apart from this
increase of speed, as in the exploration of countries
destitute of roads, but it would have no general utility.
With an automobile averaging 25 to 35 miles per hour,
almost any part of Europe, Russia excepted, was attainable
in a day's journey. A flying machine of but
equal speed would have no advantages, but if the speed
could be raised to 90 or 100 miles per hour, the whole
continent of Europe would become a playground, every
part being within a daylight flight of Berlin. Further,
some marine craft now had speeds of 40 miles per hour,
and efficiently to follow up and report movements of
such vessels an aeroplane should travel at 60 miles per
hour at least. Hence from all points of view appeared
the imperative desirability of very high velocities of
flight. The difficulties of achievement were, however,
great.

Weight of Lightest Motors.

As shown in the first lecture of his course, the resistance
to motion was nearly independent of the velocity,
so that the total work done in transporting a given
weight was nearly constant. Hence the question of fuel
economy was not a bar to high velocities of flight, though
should these become excessive, the body resistance might
constitute a large proportion of the total. The horsepower
required varied as the velocity, so the factor governing
the maximum velocity of flight was the horsepower
that could be developed on a given weight. At
present the weight per horsepower of feather-weight
motors appeared to range from 2 1/4 pounds up to 7
pounds per brake horsepower, some actual figures being
as follows:

Antoinette........ 5 lbs.
Fiat.............. 3 lbs.
Gnome....... Under 3 lbs.
Metallurgic....... 8 lbs.
Renault........... 7 lbs.
Wright.............6 lbs.

Automobile engines, on the other hand, commonly
weighed 12 pounds to 13 pounds per brake horsepower.

For short flights fuel economy was of less importance
than a saving in the weight of the engine. For long
flights, however, the case was different. Thus, if the
gasolene consumption was 1/2 pound per horsepower hour,
and the engine weighed 3 pounds per brake horsepower,
the fuel needed for a six-hour flight would weigh as much
as the engine, but for half an hour's flight its weight
would be unimportant.

Best Means of Propulsion.

The best method of propulsion was by the screw,
which acting in air was subject to much the same conditions
as obtained in marine work. Its efficiency depended
on its diameter and pitch and on its position,
whether in front of or behind the body propelled. From
this theory of dynamic support, Mr. Lanchester proceeded,
the efficiency of each element of a screw propeller
could be represented by curves such as were given
in his first lecture before the society, and from these
curves the over-all efficiency of any proposed propeller
could be computed, by mere inspection, with a fair degree
of accuracy. These curves showed that the tips of
long-bladed propellers were inefficient, as was also the
portion of the blade near the root. In actual marine
practice the blade from boss to tip was commonly of
such a length that the over-all efficiency was 95 per cent
of that of the most efficient element of it.

Advocates Propellers in Rear.

From these curves the diameter and appropriate pitch
of a screw could be calculated, and the number of
revolutions was then fixed. Thus, for a speed of 80 feet
per second the pitch might come out as 8 feet, in which
case the revolutions would be 600 per minute, which
might, however, be too low for the motor. It was then
necessary either to gear down the propeller, as was done
in the Wright machine, or, if it was decided to drive it
direct, to sacrifice some of the efficiency of the propeller.
An analogous case arose in the application of the steam
turbine to the propulsion of cargo boats, a problem as
yet unsolved. The propeller should always be aft, so
that it could abstract energy from the wake current, and
also so that its wash was clear of the body propelled.
The best possible efficiency was about 70 per cent, and
it was safe to rely upon 66 per cent.

Benefits of Soaring Flight.

There was, Mr. Lanchester proceeded, some possibility
of the aeronaut reducing the power needed for transport
by his adopting the principle of soaring flight, as
exemplified by some birds. There were, he continued, two
different modes of soaring flight. In the one the bird
made use of the upward current of air often to be found
in the neighborhood of steep vertical cliffs. These cliffs
deflected the air upward long before it actually reached
the cliff, a whole region below being thus the seat of
an upward current. Darwin has noted that the condor
was only to be found in the neighborhood of such cliffs.
Along the south coast also the gulls made frequent use
of the up currents due to the nearly perpendicular chalk
cliffs along the shore.

In the tropics up currents were also caused by
temperature differences. Cumulus clouds, moreover, were
nearly always the terminations of such up currents of
heated air, which, on cooling by expansion in the upper
regions, deposited their moisture as fog. These clouds
might, perhaps, prove useful in the future in showing
the aeronaut where up currents were to he found. An-
other mode of soaring flight was that adopted by the
albatross, which took advantage of the fact that the air
moved in pulsations, into which the bird fitted itself,
being thus able to extract energy from the wind.
Whether it would be possible for the aeronaut to employ
a similar method must be left to the future to decide.

Main Difficulties in Aviation.

In practical flight difficulties arose in starting and in
alighting. There was a lower limit to the speed at
which the machine was stable, and it was inadvisable to
leave the ground till this limit was attained. Similarly,
in alighting it was inexpedient to reduce the speed below
the limit of stability. This fact constituted a difficulty
in the adoption of high speeds, since the length of run
needed increased in proportion to the square of the
velocity. This drawback could, however, be surmounted
by forming starting and alighting grounds of ample size.
He thought it quite likely in the future that such grounds
would be considered as essential to the flying machine
as a seaport was to an ocean-going steamer or as a road
was to the automobile.

Requisites of Flying Machine.

Flying machines were commonly divided into monoplanes
and biplanes, according as they had one or two
supporting surfaces. The distinction was not, however,
fundamental. To get the requisite strength some form
of girder framework was necessary, and it was a mere
question of convenience whether the supporting surface
was arranged along both the top and the bottom of this
girder, or along the bottom only. The framework adopted
universally was of wood braced by ties of pianoforte
wire, an arrangement giving the stiffness desired with
the least possible weight. Some kind of chassis was also
necessary.

CHAPTER XXIII.

AMATEURS MAY USE WRIGHT PATENTS.

Owing to the fact that the Wright brothers have enjoined
a number of professional aviators from using
their system of control, amateurs have been slow to
adopt it. They recognize its merits, and would like to
use the system, but have been apprehensive that it
might involve them in litigation. There is no danger
of this, as will be seen by the following statement made
by the Wrights:

What Wright Brothers Say.

"Any amateur, any professional who is not exhibiting
for money, is at liberty to use our patented devices.
We shall be glad to have them do so, and there will be
no interference on our part, by legal action, or otherwise.
The only men we proceed against are those who, without
our permission, without even asking our consent,
coolly appropriate the results of our labors and use them
for the purpose of making money. Curtiss, Delagrange,
Voisin, and all the rest of them who have used our
devices have done so in money-making exhibitions. So
long as there is any money to be made by the use of the
products of our brains, we propose to have it ourselves.
It is the only way in which we can get any return for
the years of patient work we have given to the problem
of aviation. On the other hand, any man who wants
to use these devices for the purpose of pleasure, or the
advancement of science, is welcome to do so, without
money and without price. This is fair enough, is it not?"

Basis of the Wright Patents.

In a flying machine a normally flat aeroplane having
lateral marginal portions capable of movement to different
positions above or below the normal plane of the
body of the aeroplane, such movement being about an
axis transverse to the line of flight, whereby said lateral
marginal portions may be moved to different angles relatively
to the normal plane of the body of the aeroplane,
so as to present to the atmosphere different angles
of incidence, and means for so moving said lateral marginal
portions, substantially as described.

Application of vertical struts near the ends having
flexible joints.

Means for simultaneously imparting such movement
to said lateral portions to different angles relatively to
each other.

Refers to the movement of the lateral portions on the
same side to the same angle.

Means for simultaneously moving vertical rudder so
as to present to the wind that side thereof nearest the
side of the aeroplane having the smallest angle of incidence.

Lateral stability is obtained by warping the end wings
by moving the lever at the right hand of the operator,
connection being made by wires from the lever to the
wing tips. The rudder may also be curved or warped in
similar manner by lever action.

Wrights Obtain an Injunction.

In January, 1910, Judge Hazel, of the United States
Circuit Court, granted a preliminary injunction restraining
the Herring-Curtiss Co., and Glenn H. Curtiss, from
manufacturing, selling, or using for exhibition purposes
the machine known as the Curtiss aeroplane. The injunction
was obtained on the ground that the Curtiss
machine is an infringement upon the Wright patents in
the matter of wing warping and rudder control.

It is not the purpose of the authors to discuss the
subject pro or con. Such discussion would have no proper
place in a volume of this kind. It is enough to say that
Curtiss stoutly insists that his machine is not an
infringement of the Wright patents, although Judge Hazel
evidently thinks differently.

What the Judge Said.

In granting the preliminary injunction the judge said:

"Defendants claim generally that the difference in
construction of their apparatus causes the equilibrium or
lateral balance to be maintained and its aerial movement
secured upon an entirely different principle from that
of complainant; the defendants' aeroplanes are curved,
firmly attached to the stanchions and hence are incapable
of twisting or turning in any direction; that the
supplementary planes or so-called rudders are secured to
the forward stanchion at the extreme lateral ends of
the planes and are adjusted midway between the upper
and lower planes with the margins extending beyond the
edges; that in moving the supplementary planes equal
and uniform angles of incidence are presented as
distinguished from fluctuating angles of incidence. Such
claimed functional effects, however, are strongly
contradicted by the expert witness for complainant.

Similar to Plan of Wrights.

"Upon this contention it is sufficient to say that the
affidavits for the complainant so clearly define the
principle of operation of the flying machines in question
that I am reasonably satisfied that there is a variableness
of the angle of incidence in the machine of defendants
which is produced when a supplementary plane on one
side is tilted or raised and the other stimultaneously
tilted or lowered. I am also satisfied that the rear
rudder is turned by the operator to the side having the
least angle of incidence and that such turning is done
at the time the supplementary planes are raised
or depressed to prevent tilting or upsetting the machine.
On the papers presented I incline to the view, as already
indicated, that the claims of the patent in suit should be
broadly construed; and when given such construction,
the elements of the Wright machine are found in defendants'
machine performing the same functional result.
There are dissimilarities in the defendants' structure--
changes of form and strengthening of parts--which may
be improvements, but such dissimilarities seem to me to
have no bearing upon the means adopted to preserve the
equilibrium, which means are the equivalent of the claims
in suit and attain an identical result.

Variance From Patent Immaterial.

"Defendants further contend that the curved or arched
surfaces of the Wright aeroplanes in commercial use are
departures from the patent, which describes 'substantially
flat surfaces,' and that such a construction would
be wholly impracticable. The drawing, Fig. 3, however,
attached to the specification, shows a curved line inward
of the aeroplane with straight lateral edges, and considering
such drawing with the terminology of the specification,
the slight arching of the surface is not thought
a material departure; at any rate, the patent in issue
does not belong to the class of patents which requires
narrowing to the details of construction."

"June Bug" First Infringement.

Referring to the matter of priority, the judge said:

"Indeed, no one interfered with the rights of the
patentees by constructing machines similar to theirs until
in July, 1908, when Curtiss exhibited a flying machine
which he called the 'June Bug.' He was immediately
notified by the patentees that such machine with its
movable surfaces at the tips of wings infringed the patent
in suit, and he replied that he did not intend to publicly
exhibit the machine for profit, but merely was engaged
in exhibiting it for scientific purposes as a member
of the Aerial Experiment Association. To this the patentees
did not object. Subsequently, however, the machine,
with supplementary planes placed midway between
the upper and lower aeroplanes, was publicly exhibited
by the defendant corporation and used by Curtiss in
aerial flights for prizes and emoluments. It further appears
that the defendants now threaten to continue such
use for gain and profit, and to engage in the manufacture
and sale of such infringing machines, thereby becoming
an active rival of complainant in the business of
constructing flying machines embodying the claims in suit,
but such use of the infringing machines it is the duty
of this court, on the papers presented, to enjoin.

"The requirements in patent causes for the issuance
of an injunction pendente lite--the validity of the patent,
general acquiescence by the public and infringement
by the defendants--are so reasonably clear that I believe
if not probable the complainant may succeed at final
hearing, and therefore, status quo should be preserved
and a preliminary injunction granted.

"So ordered."

Points Claimed By Curtiss.

That the Herring-Curtiss Co. will appeal is a certainty.
Mr. Emerson R. Newell, counsel for the company,
states its case as follows:

"The Curtiss machine has two main supporting surfaces,
both of which are curved * * * and are absolutely
rigid at all times and cannot be moved, warped or
distorted in any manner. The front horizontal rudder is
used for the steering up or down, and the rear vertical
rudder is used only for steering to the right or left, in
the same manner as a boat is steered by its rudder. The
machine is provided at the rear with a fixed horizontal
surface, which is not present in the machine of the patent,
and which has a distinct advantage in the operation
of defendants' machine, as will be hereafter discussed.

Does Not Warp Main Surface.

"Defendants' machine does not use the warping of the
main supporting surfaces in restoring the lateral equilibrium,
but has two comparatively small pivoted balancing
surfaces or rudders. When one end of the machine
is tipped up or down from the normal, these planes may
be thrown in opposite directions by the operator, and
so steer each end of the machine up or down to its
normal level, at which time tension upon them is released
and they are moved back by the pressure of the
wind to their normal position.

Rudder Used Only For Steering.

"When defendants' balancing surfaces are moved they
present equal angles of incidence to the normal rush
of air and equal resistances, at each side of the machine,
and there is therefore no tendency to turn around a
vertical axis as is the case of the machine of the patent,
consequently no reason or necessity for turning the vertical
rear rudder in defendants' machine to counteract any
such turning tendency. At any rate, whatever may be
the theories in regard to this matter, the fact is that
the operator of defendants' machine does not at any
time turn his vertical rudder to counteract any turning
tendency clue to the side balancing surfaces, but only
uses it to steer the machine the same as a boat is
steered."

Aero Club Recognizes Wrights.

The Aero Club of America has officially recognized
the Wright patents. This course was taken following a
conference held April 9th, 1910, participated in by William
Wright and Andrew Freedman, representing the
Wright Co., and the Aero Club's committee, of Philip
T. Dodge, W. W. Miller, L. L. Gillespie, Wm. H. Page
and Cortlandt F. Bishop.

At this meeting arrangements were made by which
the Aero Club recognizes the Wright patents and will
not give its section to any open meet where the promoters
thereof have not secured a license from the
Wright Company.

The substance of the agreement was that the Aero
Club of America recognizes the rights of the owners of
the Wright patents under the decisions of the Federal
courts and refuses to countenance the infringement of
those patents as long as these decisions remain in force.

In the meantime, in order to encourage aviation, both
at home and abroad, and in order to permit foreign
aviators to take part in aviation contests in this country
it was agreed that the Aero Club of America, as the
American representative of the International Aeronautic
Federation, should approve only such public contests
as may be licensed by the Wright Company and that
the Wright Company, on the other hand, should encourage
the holding of open meets or contests where ever approved as
aforesaid by the Aero Club of America
by granting licenses to promoters who make satisfactory
arrangements with the company for its compensation
for the use of its patents. At such licensed meet any
machine of any make may participate freely without
securing any further license or permit. The details and
terms of all meets will be arranged by the committee
having in charge the interests of both organizations.

CHAPTER XXIV.

HINTS ON PROPELLER CONSTRUCTION.

Every professional aviator has his own ideas as to the
design of the propeller, one of the most important features
of flying-machine construction. While in many
instances the propeller, at a casual glance, may appear
to be identical, close inspection will develop the fact that
in nearly every case some individual idea of the designer
has been incorporated. Thus, two propellers of the two-
bladed variety, while of the same general size as to
length and width of blade, will vary greatly as to pitch
and "twist" or curvature.

What the Designers Seek.

Every designer is seeking for the same result--the
securing of the greatest possible thrust, or air displacement,
with the least possible energy.

The angles of any screw propeller blade having a
uniform or true pitch change gradually for every increased
diameter. In order to give a reasonably clear
explanation, it will be well to review in a primary way
some of the definitions or terms used in connection with
and applied to screw propellers.

Terms in General Use.

Pitch.--The term "pitch," as applied to a screw propeller,
is the theoretical distance through which it would
travel without slip in one revolution, and as applied to
a propeller blade it is the angle at which the blades are
set so as to enable them to travel in a spiral path through
a fixed distance theoretically without slip in one revolution.

Pitch speed.--The term "pitch speed" of a screw
propeller is the speed in feet multiplied by the number of
revolutions it is caused to make in one minute of time.
If a screw propeller is revolved 600 times per minute,
and if its pitch is 7 ft., then the pitch speed of such a
propeller would be 7x600 revolutions, or 4200 ft. per
minute.

Uniform pitch.--A true pitch screw propeller is one
having its blades formed in such a manner as to enable
all of its useful portions, from the portion nearest the
hub to its outer portion, to travel at a uniform pitch
speed. Or, in other words, the pitch is uniform when the
projected area of the blade is parallel along its full
length and at the same time representing a true sector
of a circle.

All screw propellers having a pitch equal to their
diameters have the same angle for their blades at their
largest diameter.

When Pitch Is Not Uniform.

A screw propeller not having a uniform pitch, but
having the same angle for all portions of its blades, or
some arbitrary angle not a true pitch, is distinguished
from one having a true pitch in the variation of the pitch
speeds that the various portions of its blades are forced
to travel through while traveling at its maximum pitch
speed.

On this subject Mr. R. W. Jamieson says in Aeronautics:

"Take for example an 8-foot screw propeller having an
8-foot pitch at its largest diameter. If the angle is the
same throughout its entire blade length, then all the porions
of its blades approaching the hub from its outer portion would
have a gradually decreasing pitch. The 2-foot
portion would have a 2-foot pitch; the 3-foot portion a 3-
foot pitch, and so on to the 8-foot portion which would
have an 8-foot pitch. When this form of propeller is
caused to revolve, say 500 r.p.m., the 8-foot portion would
have a calculated pitch speed of 8 feet by 500 revolutions,
or 4,000 feet per min.; while the 2-foot portion would
have a calculated pitch speed of 500 revolutions by 2 feet,
or 1,000 feet per minute.

Effect of Non-Uniformity.

"Now, as all of the portions of this type of screw
propeller must travel at some pitch speed, which must have
for its maximum a pitch speed in feet below the calculated
pitch speed of the largest diameter, it follows that
some portions of its blades would perform useful work
while the action of the other portions would be negative
--resisting the forward motion of the portions having a
greater pitch speed. The portions having a pitch speed
below that at which the screw is traveling cease to perform
useful work after their pitch speed has been exceeded

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