Aircraft model blog

All aviators agree that these unequal areas of
density extend over small spaces, and it is, therefore,
obvious that a machine which is of such a
structure that it moves through the air broadside
on, will be more liable to meet these inequalities
than one which is narrow and does not take in such
a wide path.
Why, therefore, persist in making a form which,
by its very nature, invites danger? Because birds
fly that way!
THE TURNING MOVEMENT.–This structural arrangement
accentuates the difficulty when the machine
turns. The air pressure against the wing
surface is dependent on the speed. The broad
outstretched surfaces compel the wing at the outer
side of the circle to travel faster than the inner
one. As a result, the outer end of the aeroplane
is elevated.
CENTRIFUGAL ACTION.–At the same time the
running gear, and the frame which carries it and
supports the machine while at rest, being below
the planes, a centrifugal force is exerted, when
turning a circle, which tends to swing the wheels
and frame outwardly, and thereby still further
elevating the outer end of the plane.
THE WARPING PLANES.–The only remedy to
meet this condition is expressed in the mechanism
which wraps or twists the outer ends of the planes,
as constructed in the Wright machine, or the
ailerons, or small wings at the rear margins of the
planes, as illustrated by the Farman machine.
The object of this arrangement is to decrease the
angle of incidence at the rising end, and increase
the angle at the depressed end, and thus, by manually-
operated means keep the machine on an even
keel.
CHAPTER IV
FORE AND AFT CONTROL
THERE is no phase of the art of flying more important
than the fore and aft control of an airship.
Lateral stability is secondary to this feature, for
reasons which will appear as we develop the
subject.
THE BIRD TYPE OF FORE AND AFT CONTROL.–
Every aeroplane follows the type set by nature
in the particular that the body is caused to oscillate
on a vertical fore and aft plane while in
flight. The bird has one important advantage,
however, in structure. Its wing has a flexure at
the joint, so that its body can so oscillate independently
of the angle of the wings.
The aeroplane has the wing firmly fixed to the
body, hence the only way in which it is possible
to effect a change in the angle of the wing is by
changing the angle of the body. To be consistent
the aeroplane should be so constructed that the
angle of the supporting surfaces should be movable,
and not controllable by the body.
The bird, in initiating flight from a perch, darts
downwardly, and changes the angle of the body to
correspond with the direction of the flying start.
When it alights the body is thrown so that its
breast banks against the air, but in ordinary flight
its wings only are used to change the angle of
flight.
ANGLE AND DIRECTION OF FLIGHT.–In order to
become familiar with terms which will be frequently
used throughout the book, care should be
taken to distinguish between the terms angle and
direction of flight. The former has reference to
the up and down movement of an aeroplane,
whereas the latter is used to designate a turning
movement to the right or to the left.
WHY SHOULD THE ANGLE OF THE BODY CHANGE?
–The first question that presents itself is, why
should the angle of the aeroplane body change?
Why should it be made to dart up and down and
produce a sinuous motion? Why should its nose
tilt toward the earth, when it is descending, and
raise the forward part of the structure while ascending?
The ready answer on the part of the bird-form
advocate is, that nature has so designed a flying
structure. The argument is not consistent, because
in this respect, as in every other, it is not
made to conform to the structure which they seek
to copy.
CHANGING ANGLE OF BODY NOT SAFE.–Furthermore,
there is not a single argument which can be
advanced in behalf of that method of building,
which proves it to be correct. Contrariwise, an
analysis of the flying movement will show that it is
the one feature which has militated against safety,
and that machines will never be safe so long as
the angle of the body must be depended upon to
control the angle of flying.
_Fig. 11a Monoplane in Flight._

All aviators agree that these unequal areas of
density extend over small spaces, and it is, therefore,
obvious that a machine which is of such a
structure that it moves through the air broadside
on, will be more liable to meet these inequalities
than one which is narrow and does not take in such
a wide path.
Why, therefore, persist in making a form which,
by its very nature, invites danger? Because birds
fly that way!
THE TURNING MOVEMENT.–This structural arrangement
accentuates the difficulty when the machine
turns. The air pressure against the wing
surface is dependent on the speed. The broad
outstretched surfaces compel the wing at the outer
side of the circle to travel faster than the inner
one. As a result, the outer end of the aeroplane
is elevated.
CENTRIFUGAL ACTION.–At the same time the
running gear, and the frame which carries it and
supports the machine while at rest, being below
the planes, a centrifugal force is exerted, when
turning a circle, which tends to swing the wheels
and frame outwardly, and thereby still further
elevating the outer end of the plane.
THE WARPING PLANES.–The only remedy to
meet this condition is expressed in the mechanism
which wraps or twists the outer ends of the planes,
as constructed in the Wright machine, or the
ailerons, or small wings at the rear margins of the
planes, as illustrated by the Farman machine.
The object of this arrangement is to decrease the
angle of incidence at the rising end, and increase
the angle at the depressed end, and thus, by manually-
operated means keep the machine on an even
keel.
CHAPTER IV
FORE AND AFT CONTROL
THERE is no phase of the art of flying more important
than the fore and aft control of an airship.
Lateral stability is secondary to this feature, for
reasons which will appear as we develop the
subject.
THE BIRD TYPE OF FORE AND AFT CONTROL.–
Every aeroplane follows the type set by nature
in the particular that the body is caused to oscillate
on a vertical fore and aft plane while in
flight. The bird has one important advantage,
however, in structure. Its wing has a flexure at
the joint, so that its body can so oscillate independently
of the angle of the wings.
The aeroplane has the wing firmly fixed to the
body, hence the only way in which it is possible
to effect a change in the angle of the wing is by
changing the angle of the body. To be consistent
the aeroplane should be so constructed that the
angle of the supporting surfaces should be movable,
and not controllable by the body.
The bird, in initiating flight from a perch, darts
downwardly, and changes the angle of the body to
correspond with the direction of the flying start.
When it alights the body is thrown so that its
breast banks against the air, but in ordinary flight
its wings only are used to change the angle of
flight.
ANGLE AND DIRECTION OF FLIGHT.–In order to
become familiar with terms which will be frequently
used throughout the book, care should be
taken to distinguish between the terms angle and
direction of flight. The former has reference to
the up and down movement of an aeroplane,
whereas the latter is used to designate a turning
movement to the right or to the left.
WHY SHOULD THE ANGLE OF THE BODY CHANGE?
–The first question that presents itself is, why
should the angle of the aeroplane body change?
Why should it be made to dart up and down and
produce a sinuous motion? Why should its nose
tilt toward the earth, when it is descending, and
raise the forward part of the structure while ascending?
The ready answer on the part of the bird-form
advocate is, that nature has so designed a flying
structure. The argument is not consistent, because
in this respect, as in every other, it is not
made to conform to the structure which they seek
to copy.
CHANGING ANGLE OF BODY NOT SAFE.–Furthermore,
there is not a single argument which can be
advanced in behalf of that method of building,
which proves it to be correct. Contrariwise, an
analysis of the flying movement will show that it is
the one feature which has militated against safety,
and that machines will never be safe so long as
the angle of the body must be depended upon to
control the angle of flying.
_Fig. 11a Monoplane in Flight._

Another good example of this type of engine was the Eole, which
had eight opposed pistons, each pair of which was actuated by a
common combustion chamber at the centre of the engine, two
crankshafts being placed at the outer ends of the engine. This
reversal of the ordinary arrangement had two advantages; it
simplified induction, and further obviated the need for cylinder
heads, since the explosion drove at two piston heads instead of
at one piston head and the top of the cylinder; against this,
however, the engine had to be constructed strongly enough to
withstand the longitudinal stresses due to the explosions, as
the cranks are placed on the outer ends and the cylinders and
crank-cases take the full force of each explosion. Each
crankshaft drove a separate air-screw.
This pattern of engine was taken up by the Dutheil-Chambers firm
in the pioneer days of aircraft, when the firm in question
produced seven different sizes of horizontal engines. The
Demoiselle monoplane used by Santos-Dumont in 1909 was fitted
with a two-cylinder, horizontally-opposed Dutheil-Chambers
engine, which developed 25 brake horse-power at a speed of
1,100 revolutions per minute, the cylinders being of 5 inches
bore by 5.1 inches stroke, and the total weight of the engine
being some 120 lbs. The crankshafts of these engines were
usually fitted with steel flywheels in order to give a very even
torque, the wheels being specially constructed with wire spokes.
In all the Dutheil-Chambers engines water cooling was adopted,
and the cylinders were attached to the crank cases by means of
long bolts passing through the combustion heads.
For their earliest machines, the Clement-Bayard firm constructed
horizontal engines of the opposed piston type. The best known of
these was the 30 horse-power size, which had cylinders of 4.7
inches diameter by 5.1 inches stroke, and gave its rated power
at 1,200 revolutions per minute. In this engine the steel
cylinders were secured to the crank case by flanges, and
radiating ribs were formed around the barrel to assist the
air-cooling. Inlet and exhaust valves were actuated by
push-rods and rockers actuated from the second motion shaft
mounted above the crank case; this shaft also drove the
high-tension magneto with which the engine was fitted. A ring
of holes drilled round each cylinder constituted auxiliary ports
which the piston uncovered at the inner end of its stroke, and
these were of considerable assistance not only in expelling
exhaust gases, but also in moderating the temperature of the
cylinder and of the main exhaust valve fitted in the cylinder
head. A water-cooled Clement-Bayard horizontal engine was also
made, and in this the auxiliary exhaust ports were not embodied;
except in this particular, the engine was very similar to the
water-cooled Darracq.
The American Ashmusen horizontal engine, developing 100
horse-power, is probably the largest example of this type
constructed. It was made with six cylinders arranged on each
side of a common crank case, with long bolts passing through the
cylinder heads to assist in holding them down. The induction
piping and valve-operating gear were arranged below the engine,
and the half-speed shaft carried the air-screw.

In the second place, there should be time limits placed by law
covering the period of usefulness of various parts of an airplane.
After fifty hours of flying there should be an inspection of certain
working parts of the engine, certain wires in the body which may be
strained by bad landings, and other wires in the rigging strained by
flying in bad weather New wires are always sagging and stretching a
bit. Wings will “wash out,” lose their usefulness by excessive flying,
and must be replaced. There is a great volume of data on these matters
which should be the basis for laws covering mechanical inspection of
airplanes, and with which the airplane mechanic must become familiar.
For the man who would like to work into the piloting of aircraft there
is a very good opportunity by starting with the mechanical side. Too
many pilots know next to nothing about the construction of their
machines. When an engine goes bad they know that it wont run–that is
all. The pilot who is a good mechanic is a gifted man in his
profession.
There are endless opportunities at flying-fields for mechanics who
want to learn to fly. During the war it became customary to take
mechanics up for flying at least once in two weeks on some fields. It
gave the mechanic an interest in his work and an interest in the life
of his pilot. Perhaps nothing stimulated accurate work by a mechanic
more than the knowledge that at any time he might be called upon to
ride in one of the planes he had helped make or repair.
Some were taught flying by their officers, and later qualified as
pilots. Others went through as cadets and became pilots after the
regular course. The pilot of the future must learn the mechanical
side, and the mechanic should be a good pilot. The two must go hand in
hand to make flying a success.

PART IV
CROSS COUNTRY
The Aeroplane had been designed and built, and tested in
the air, and now stood on the Aerodrome ready for its first
cross-country flight.
It had run the gauntlet of pseudo-designers, crank inventors,
press “experts, and politicians; of manufacturers
keen on cheap work and large profits; of poor pilots who had
funked it, and good pilots who had expected too much of
it. Thousands of pounds had been wasted on it, many had
gone bankrupt over it, and others it had provided with safe
fat jobs.
Somehow, and despite every conceivable obstacle, it had
managed to muddle through, and now it was ready for its
work. It was not perfect, for there were fifty different
ways in which it might be improved, some of them shamefully
obvious. But it was fairly sound mechanically, had a little
inherent stability, was easily controlled, could climb a thousand
feet a minute, and its speed was a hundred miles an
hour. In short, quite a creditable machine, though of course
the right man had not got the credit.
It is rough, unsettled weather with a thirty mile an
hour wind on the ground, and that means fifty more or
less aloft. Lots of clouds at different altitudes to bother
the Pilot, and the air none to clear for the observation of
landmarks.
As the Pilot and Observer approach the Aeroplane the
former is clearly not in the best of tempers. “Its rotten
luck, he is saying, “a blank shame that I should have
to take this blessed bus and join X Reserve Squadron,
stationed a hundred and fifty miles from anywhere; and
just as I have licked my Flight into shape. Now some
slack blighter will, I suppose, command it and get the credit
of all my work!
“Shut up, you grouser, said the Observer. “Do you
think youre the only one with troubles? Havent I been
through it too? Oh! I know all about it! Youre from
the Special Reserve and your C.O. doesnt like your style
of beauty, and you wont lick his boots, and you were a bit
of a technical knut in civil life, but now youve jolly well
got to know less than those senior to you. Well! Its a
jolly good experience for most of us. Perhaps conceit wont
be at quite such a premium after this war. And whats
the use of grousing? That never helped anyone. So buck
up, old chap. Your day will come yet. Heres our machine,
and I must say it looks a beauty!
And, as the Pilot approaches the Aeroplane, his face
brightens and he soon forgets his troubles as he critically
inspects the craft which is to transport him and the Observer
over the hills and far away. Turning to the Flight-Sergeant
he inquires, “Tank full of petrol and oil?
“Yes, sir, he replies, “and everything else all correct.
Propeller, engine and body covers on board, sir; tool kit
checked over and in the locker; engine and Aeroplane logbooks
written up, signed, and under your seat; engine revs.
up to mark, and all the control cables in perfect condition
and tension.
“Very good, said the Pilot; and then turning to the
Observer, “Before we start you had better have a look
at the course I have mapped out.
“A is where we stand and we have to reach B, a hundred
and fifty miles due North. I judge that, at the altitude
we shall fly, there will be an East wind, for although it is
not quite East on the ground it is probably about twenty
degrees different aloft, the wind usually moving round clockways
to about that extent. I think that it is blowing at the
rate of about fifty miles an hour, and I therefore take a line
on the map to C, fifty miles due West of A. The Aeroplanes
speed is a hundred miles an hour, and so I take a line of one
hundred miles from C to D. Our compass course will then
be in the direction A–E, which is always a line parallel to

Photographers may yet take the place of surveyors, or work hand in
hand with them in the making of aerial maps of the country. The map of
the future must be an aerial map, a mosaic map such as was used by our
army headquarters. Nothing can exceed the eye of the camera for
accuracy. Cameras bolted to airplanes, such as were used by our army
for reconnaissance, have already been used for mapping cities. The
mapping of the entire country in such a manner is only a matter of
time.
One thing which an aviation mechanic of any sort must bear in mind is
that he _must_ do his work with a conscience. True, he is handling
mute metal engines, or dumb wires and struts–but in his work he holds the life of the pilot in his hand. It is not too much to say that
hundreds of pilots lives have been saved by the conscientious work of
skilled mechanics who realized the danger of the air.
I have seen mechanics rush from a hangar in a frenzy of excitement
and agitation. “That machine must not go up; it has been repaired, but
not inspected!” They have done their work with a will in the army;
they have learned some of the dangers of flying and weak spots which
must be watched. The civilian mechanic must be taught many things.
First of all he must know the value of inspection. Every machine which
has gone through a workshop must be inspected and checked over by a
skilled mechanic before a pilot is allowed to fly it. The ideal thing
would be to have legislation licensing the inspectors of aircraft and
requiring that repairs on all machines be examined by a licensed
inspector. The inspectors would be under civil service and would be
selected by competitive examination. It may sound fantastic, but such
precautions are as necessary for the preservation of life as
legislation on sanitary matters.

Early in 1914 it became known that the experimental work of
Edward Busk–who was so lamentably killed during an experimental
flight later in the year–following upon the researches of
Bairstow and others had resulted in the production at the Royal
Aircraft Factory at Farnborough of a truly automatically stable
aeroplane. This was the R.E. (Reconnaissance Experimental), a
development of the B.E. which has already been referred to. The
remarkable feature of this design was that there was no
particular device to which one could point out as the cause of
the stability. The stable result was attained simply by detailed
design of each part of the aeroplane, with due regard to its
relation to, and effect on, other parts in the air. Weights and
areas were so nicely arranged that under practically any
conditions the machine tended to right itself. It did not,
therefore, claim to be a machine which it was impossible to
upset, but one which if left to itself would tend to right itself
from whatever direction a gust might come. When the principles
were extended to the B.E. 2c type (largely used at the outbreak
of the War) the latter machine, if the engine were switched of f
at a height of not less than 1,000 feet above the ground, would
after a few moments assume its correct gliding angle and glide
down to the ground.
The Paris Aero Salon of December, 1913, had been remarkable
chiefly for the large number of machines of which the chassis and
bodywork had been constructed of steel-tubing; for the excess of
monoplanes over biplanes; and (in the latter) predominance of
pusher machines (with propeller in rear of the main planes)
compared with the growing British preference for tractors (with
air screw in front). Incidentally, the Maurice Farman, the last
relic of the old type box-kite with elevator in front appeared
shorn of this prefix, and became known as the short-horn in
contradistinction to its front-elevatored predecessor which,
owing to its general reliability and easy flying capabilities,
had long been affectionately called the mechanical cow. The
1913 Salon also saw some lingering attempts at attaining
automatic stability by pendulum and other freak devices.
Apart from the appearance of R.E.1, perhaps the most notable
development towards the end of 1913 was the appearance of the
Sopwith Tabloid tractor biplane. This single-seater machine,
evolved from the two-seater previously referred to, fitted with a
Gnome engine of 80 horse-power, had the, for those days,
remarkable speed of 92 miles an hour; while a still more
notable feature was that it could remain in level flight at not
more than 37 miles per hour. This machine is of particular
importance because it was the prototype and forerunner of the
successive designs of single-seater scout fighting machines
which were used so extensively from 1914 to 1918. It was also
probably the first machine to be capable of reaching a height of
1,000 feet within one minute. It was closely followed by the
Bristol Bullet, which was exhibited at the Olympia Aero Show
of March, 1914. This last pre-war show was mainly remarkable
for the good workmanship displayed–rather than for any distinct
advance in design. In fact, there was a notable diversity in
the types displayed, but in detailed design considerable
improvements were to be seen, such as the general adoption of
stranded steel cable in place of piano wire for the mail bracing

The task is one of the greatest, the most vital, and the most
promising which mankind has ever faced. With the general theories
proved and demonstrated, the great crisis of invention has passed, and
the slow, unspectacular process of development and application has set
in. Now has come the time for serious, sober thought, for careful,
analytical planning, for vision combined with hopefulness. It is well
in these early days, when flight is with the general public a very
special and occasional event, to remember what has happened since Watt
developed the steam-engine only a few generations ago, when Columbus
set the first ship westward, or when Americas first train ran over
its rough tracks near the Quincy quarries.
The development of aviation will be world-wide and will include all
sorts and races of men. The nations all start pretty much abreast.
Those which developed war air services have an advantage in material
and experience, but this is a matter only for the moment. The main
lines of progress are now pretty widely known and the field is wide
open to those who have the imagination to enter it. There is
practically no handicap at this early stage which cannot be overcome
with ease.
There is, of course, an element of individual gamble to those who
enter this competition. Undoubtedly there will be many failures, as in
all new fields; failures come to those who put in capital as well as
those who contribute their scientific knowledge. But by the same token
there will be great successes both financially and scientifically. The
prize that is being striven for is one of the richest that have ever
been offered and the rewards will be in accordance. This has been the
case at the birth of every great development in human progress and
will undoubtedly be the case with the science of flight. Until a field
becomes standardized it offers extremes on both sides rather than a
dull, dreary, but safe average.
As aviation runs into every phase of activity it will require every
kind of man–manufacturer, scientist, mechanic, and flier. It offers
problems more interesting and more complex than almost any others in
the world. The field is new and virgin, the demand world-wide, and the
rewards great. For the flier there is all the joy of life in the air,
above the chains of the earth, reaching out to new, unvisited regions,
free to come and go for almost any distance at any level desired, a
freedom unparalleled. For the manufacturer there is all the lure of a
new product destined in a short time to be used as freely as the
automobile of to-day; for the scientist there are problems of balance,
meteorology, air pressure, engine power, wing spread, altitude
effects, and the like in a bewildering variety; for the explorer, the
geographer, the map-maker a wholly new field is laid open.

With regard to boilers, Maxim writes,
The first boiler which I made was constructed something on the
Herreshof principle, but instead of having one simple pipe in
one very long coil, I used a series of very small and light
pipes, connected in such a manner that there was a rapid
circulation through the whole–the tubes increasing in size and
number as the steam was generated. I intended that there should
be a pressure of about 100 lbs. more on the feed water end of
the series than on the steam end, and I believed that this
difference in pressure would be sufficient to ensure direct and
positive circulation through every tube in the series. The first
boiler was exceedingly light, but the workmanship, as far as
putting the tubes together was concerned, was very bad, and it
was found impossible to so adjust the supply of water as to make
dry steam without overheating and destroying the tubes.
Before making another boiler I obtained a quantity of copper
tubes, about 8 feet long, 3/8 inch external diameter, and 1/50 of
an inch thick. I subjected about 100 of these tubes to an
internal pressure of 1 ton per square inch of cold kerosene oil,
and as none of them leaked I did not test any more, but
commenced my experiments by placing some of them in a white-hot
petroleum fire. I found that I could evaporate as much as 26
1/2 lbs. of water per square foot of heating surface per hour,
and that with a forced circulation, although the quantity of
water passing was very small but positive, there was no danger
of overheating. I conducted many experiments with a pressure of
over 400 lbs. per square inch, but none of the tubes failed.
I then mounted a single tube in a white-hot furnace, also with a
water circulation, and found that it only burst under steam at a
pressure of 1,650 lbs. per square inch. A large boiler,
having about 800 square feet of heating surface, including the
feed-water heater, was then constructed. This boiler is about 4
1/2 feet wide at the bottom, 8 feet long and 6 feet high. It
weighs, with the casing, the dome, and the smoke stack and
connections, a little less than 1,000 lbs. The water first
passes through a system of small tubes–1/4 inch in diameter and
1/60 inch thick–which were placed at the top of the boiler and
immediately over the large tubes…. This feed-water heater is
found to be very effective. It utilises the heat of the
products of combustion after they have passed through the boiler
proper and greatly reduces their temperature, while the
feed-water enters the boiler at a temperature of about 250 F. A
forced circulation is maintained in the boiler, the feed-water
entering through a spring valve, the spring valve being adjusted
in such a manner that the pressure on the water is always 30
lbs. per square inch in excess of the boiler pressure. This
fall of 30 lbs. in pressure acts upon the surrounding hot water
which has already passed through the tubes, and drives it down
through a vertical outside tube, thus ensuring a positive and
rapid circulation through all the tubes. This apparatus is
found to act extremely well.
Thus Maxim, who with this engine as power for his large
aeroplane achieved free flight once, as a matter of experiment,
though for what distance or time the machine was actually off
the ground is matter for debate, since it only got free by
tearing up the rails which were to have held it down in the
experiment. Here, however, was a steam engine which was
practicable for use in the air, obviously, and only the rapid
success of the internal combustion engine prevented the
steam-producing type from being developed toward perfection.

After these antics, I decreased the extent of the possible
change in the form of wing-surface, so as to allow only straight
sailing or only long curves in turning.
During my work I had a few carping critics that I silenced by
this standing offer: If they would deposit a thousand dollars I
would cover it on this proposition. I would fasten a 150 pound
sack of sand in the riders seat, make the necessary
adjustments, and send up an aeroplane upside down with a
balloon, the aeroplane to be liberated by a time fuse. If the
aeroplane did not immediately right itself, make a flight, and
come safely to the ground, the money was theirs.
Now a word in regard to the fatal accident. The circumstances are these: The ascension was given to entertain a military
company in which were many of Maloneys friends, and he had told
them he would give the most sensational flight they ever heard
of. As the balloon was rising with the aeroplane, a guy rope
dropping switched around the right wing and broke the tower that
braced the two rear wings and which also gave control over the
tail. We shouted Maloney that the machine was broken, but he
probably did not hear us, as he was at the same time saying,
“Hurrah for Montgomerys airship,” and as the break was behind
him, he may not have detected it. Now did he know of the
breakage or not, and if he knew of it did he take a risk so as
not to disappoint his friends? At all events, when the machine
started on its flight the rear wings commenced to flap (thus
indicating they were loose), the machine turned on its back, and
settled a little faster than a parachute. When we reached