There are three distinct and radically different forms

of flying machines. These are:

Aeroplanes, helicopters and ornithopers.

Of these the aeroplane takes precedence and is used

almost exclusively by successful aviators, the helicopters

and ornithopers having been tried and found lacking in

some vital features, while at the same time in some

respects the helicopter has advantag
s not found in the


What the Helicopter Is.

The helicopter gets its name from being fitted with

vertical propellers or helices (see illustration) by the

action of which the machine is raised directly from the

ground into the air. This does away with the necessity

for getting the machine under a gliding headway before

it floats, as is the case with the aeroplane, and consequently

the helicopter can be handled in a much smaller

space than is required for an aeroplane. This, in many

instances, is an important advantage, but it is the only

one the helicopter possesses, and is more than overcome

by its drawbacks. The most serious of these is that the

helicopter is deficient in sustaining capacity, and requires

too much motive power.

Form of the Ornithopter.

The ornithopter has hinged planes which work like

the wings of a bird. At first thought this would seem

to be the correct principle, and most of the early experimenters

conducted their operations on this line. It

is now generally understood, however, that the bird in

soaring is in reality an aeroplane, its extended wings

serving to sustain, as well as propel, the body. At any

rate the ornithoper has not been successful in aviation,

and has been interesting mainly as an ingenious toy.

Attempts to construct it on a scale that would permit

of its use by man in actual aerial flights have been far

from encouraging.

Three Kinds of Aeroplanes.

There are three forms of aeroplanes, with all of which

more or less success has been attained. These are:

The monoplane, a one-surfaced plane, like that used

by Bleriot.

The biplane, a two-surfaced plane, now used by the

Wrights, Curtiss, Farman, and others.

The triplane, a three-surfaced plane This form is

but little used, its only prominent advocate at present

being Elle Lavimer, a Danish experimenter, who has not

thus far accomplished much.

Whatever of real success has been accomplished in

aviation may be credited to the monoplane and biplane,

with the balance in favor of the latter. The monoplane

is the more simple in construction and, where weight-

sustaining capacity is not a prime requisite, may

probably be found the most convenient. This opinion is

based on the fact that the smaller the surface of the

plane the less will be the resistance offered to the air,

and the greater will be the speed at which the machine

may be moved. On the other hand, the biplane has a

much greater plane surface (double that of a monoplane

of the same size) and consequently much greater weight-

carrying capacity.

Differences in Biplanes.

While all biplanes are of the same general construction

so far as the main planes are concerned, each aviator

has his own ideas as to the "rigging."

Wright, for instance, places a double horizontal rudder

in front, with a vertical rudder in the rear. There

are no partitions between the main planes, and the

bicycle wheels used on other forms are replaced by skids.

Voisin, on the contrary, divides the main planes with

vertical partitions to increase stability in turning; uses

a single-plane horizontal rudder in front, and a big box-

tail with vertical rudder at the rear; also the bicycle


Curtiss attaches horizontal stabilizing surfaces to the

upper plane; has a double horizontal rudder in front,

with a vertical rudder and horizontal stabilizing surfaces

in rear. Also the bicycle wheel alighting gear.