It is a mistaken idea that flying machines must be

operated at extreme altitudes. True, under the impetus

of handsome prizes, and the incentive to advance scientific

knowledge, professional aviators have ascended to

considerable heights, flights at from 500 to 1,500 feet being

now common with such experts as Farman, Bleriot,

Latham, Paulhan, Wright and Curtiss. The altitude

record at this time is about 4,1
5 feet, held by Paulhan.

One of the instructions given by experienced aviators

to pupils, and for which they insist upon implicit obeyance, is:

"If your machine gets more than 30 feet high,

or comes closer to the ground than 6 feet, descend at

once." Such men as Wright and Curtiss will not tolerate

a violation of this rule. If their instructions are

not strictly complied with they decline to give the offender

further lessons.

Why This Rule Prevails.

There is good reason for this precaution. The higher

the altitude the more rarefied (thinner) becomes the air,

and the less sustaining power it has. Consequently the

more difficult it becomes to keep in suspension a given

weight. When sailing within 30 feet of the ground sustentation

is comparatively easy and, should a fall occur,

the results are not likely to be serious. On the other

hand, sailing too near the ground is almost as objectionable

in many ways as getting up too high. If the craft

is navigated too close to the ground trees, shrubs, fences

and other obstructions are liable to be encountered.

There is also the handicap of contrary air currents

diverted by the obstructions referred to, and which will

be explained more fully further on.

How to Make a Start.

Taking it for granted that the beginner has familiarized

himself with the manipulation of the machine, and especially

the control mechanism, the next thing in order

is an actual flight. It is probable that his machine will

be equipped with a wheeled alighting gear, as the skids

used by the Wrights necessitate the use of a special

starting track. In this respect the wheeled machine is

much easier to handle so far as novices are concerned

as it may be easily rolled to the trial grounds. This,

as in the case of the initial experiments, should be a

clear, reasonably level place, free from trees, fences,

rocks and similar obstructions with which there may be

danger of colliding.

The beginner will need the assistance of three men.

One of these should take his position in the rear of the

machine, and one at each end. On reaching the trial

ground the aviator takes his seat in the machine and,

while the men at the ends hold it steady the one in the rear

assists in retaining it until the operator is ready. In the

meantime the aviator has started his motor. Like the

glider the flying machine, in order to accomplish the

desired results, should be headed into the wind.

When the Machine Rises.

Under the impulse of the pushing movement, and assisted

by the motor action, the machine will gradually

rise from the ground--provided it has been properly

proportioned and put together, and everything is in working

order. This is the time when the aviator requires

a cool head, At a modest distance from the ground use

the control lever to bring the machine on a horizontal

level and overcome the tendency to rise. The exact

manipulation of this lever depends upon the method of

control adopted, and with this the aviator is supposed

to have thoroughly familiarized himself as previously

advised in chapter XI.

It is at this juncture that the operator must act

promptly, but with the perfect composure begotten of

confidence. One of the great drawbacks in aviation by

novices is the tendency to become rattled, and this is

much more prevalent than one might suppose, even

among men who, under other conditions, are cool and

confident in their actions.

There is something in the sensation of being suddenly

lifted from the ground, and suspended in the air that is

disconcerting at the start, but this will soon wear off if

the experimenter will keep cool. A few successful flights

no matter how short they may be, will put a lot of

confidence into him.

Make Your Flights Short.

Be modest in your initial flights. Don't attempt to

match the records of experienced men who have devoted

years to mastering the details of aviation. Paulhan,

Farman, Bleriot, Wright, Curtiss, and all the rest of

them began, and practiced for years, in the manner here

described, being content to make just a little advancement

at each attempt. A flight of 150 feet, cleanly and

safely made, is better as a beginning than one of 400

yards full of bungling mishaps.

And yet these latter have their uses, provided the

operator is of a discerning mind and can take advantage

of them as object lessons. But, it is not well to invite

them. They will occur frequently enough under the

most favorable conditions, and it is best to have them

come later when the feeling of trepidation and uncertainty

as to what to do has worn off.

Above all, don't attempt to fly too high. Keep within

a reasonable distance from the ground--about 25 or 30

feet. This advice is not given solely to lessen the risk

of serious accident in case of collapse, but mainly because

it will assist to instill confidence in the operator.

It is comparatively easy to learn to swim in shallow

water, but the knowledge that one is tempting death in

deep water begets timidity.

Preserving the Equilibrium.

After learning how to start and stop, to ascend and

descend, the next thing to master is the art of preserving

equilibrium, the knack of keeping the machine perfectly

level in the air--on an "even keel," as a sailor would

say. This simile is particularly appropriate as all aviators

are in reality sailors, and much more daring ones

than those who course the seas. The latter are in craft

which are kept afloat by the buoyancy of the water,

whether in motion or otherwise and, so long as normal

conditions prevail, will not sink. Aviators sail the air

in craft in which constant motion must be maintained in

order to ensure flotation.

The man who has ridden a bicycle or motorcycle

around curves at anything like high speed, will have a

very good idea as to the principle of maintaining equilibrium

in an airship. He knows that in rounding curves

rapidly there is a marked tendency to change the direction

of the motion which will result in an upset unless

he overcomes it by an inclination of his body in an opposite

direction. This is why we see racers lean well

over when taking the curves. It simply must be done

to preserve the equilibrium and avoid a spill.

How It Works In the Air.

If the equilibrium of an airship is disturbed to an

extent which completely overcomes the center of gravity

it falls according to the location of the displacement.

If this displacement, for instance, is at either end the

apparatus falls endways; if it is to the front or rear, the

fall is in the corresponding direction.

Owing to uncertain air currents--the air is continually

shifting and eddying, especially within a hundred feet or

so of the earth--the equilibrium of an airship is almost

constantly being disturbed to some extent. Even if this

disturbance is not serious enough to bring on a fall it

interferes with the progress of the machine, and should

be overcome at once. This is one of the things connected

with aerial navigation which calls for prompt,

intelligent action.

Frequently, when the displacement is very slight, it

may be overcome, and the craft immediately righted by

a mere shifting of the operator's body. Take, for illustration,

a case in which the extreme right end of the

machine becomes lowered a trifle from the normal level.

It is possible to bring it back into proper position by

leaning over to the left far enough to shift the weight

to the counter-balancing point. The same holds good as

to minor front or rear displacements.

When Planes Must Be Used.

There are other displacements, however, and these are

the most frequent, which can be only overcome by manipulation of

the stabilizing planes. The method of procedure

depends upon the form of machine in use. The

Wright machine, as previously explained, is equipped

with plane ends which are so contrived as to admit of

their being warped (position changed) by means of the

lever control. These flexible tip planes move simultaneously,

but in opposite directions. As those on one end

rise, those on the other end fall below the level of the

main plane. By this means air is displaced at one point,

and an increased amount secured in another.

This may seem like a complicated system, but its

workings are simple when once understood. It is by

the manipulation or warping of these flexible tips that

transverse stability is maintained, and any tendency to

displacement endways is overcome. Longitudinal stability

is governed by means of the front rudder.

Stabilizing planes of some form are a feature, and a

necessary feature, on all flying machines, but the methods

of application and manipulation vary according to the

individual ideas of the inventors. They all tend, however,

toward the same end--the keeping of the machine

perfectly level when being navigated in the air.

When to Make a Flight.

A beginner should never attempt to make a flight

when a strong wind is blowing. The fiercer the wind,

the more likely it is to be gusty and uncertain, and the

more difficult it will be to control the machine. Even

the most experienced and daring of aviators find there

is a limit to wind speed against which they dare not

compete. This is not because they lack courage, but

have the sense to realize that it would be silly and useless.

The novice will find a comparatively still day, or one

when the wind is blowing at not to exceed 15 miles an

hour, the best for his experiments. The machine will be

more easily controlled, the trip will be safer, and also

cheaper as the consumption of fuel increases with the

speed of the wind against which the aeroplane is forced.