Since the first edition of this book was printed, early in 1910,

there has been a remarkable advance in the construction of

aeroplane motors, which has resulted in a wonderful decrease

in the amount of surface area from that formerly required.

Marked gain in lightness and speed of the motor has enabled

aviators to get along, in some instances, with one-quarter of

the plane supporting area previously used. The first Wri

biplane, propelled by a motor of 25 h.p., productive of a fair

average speed of 30 miles an hour, had a plane surface of 538

square feet. Now, by using a specially designed motor of 65

h. p., capable of developing a speed of from 70 to 80 miles an

hour, the Wrights are enabled to successfully navigate a machine

the plane area of which is about 130 square feet. This

apparatus is intended to carry only one person (the operator).

At Belmont Park, N. Y., the Wrights demonstrated that the

small-surfaced biplane is much faster, easier to manage in the

hands of a skilled manipulator, and a better altitude climber

than the large and cumbersome machines with 538 square feet

of surface heretofore used by them.

In this may be found a practical illustration of the principle

that increased speed permits of a reduction in plane area in

mathematical ratio to the gain in speed. The faster any object

can be made to move through the air, the less will be the


surface required to sustain a given weight. But, there

is a limit beyond which the plane surface cannot be reduced

with safety. Regard must always be had to the securing of

an ample sustaining surface so that in case of motor stoppage

there will be sufficient buoyancy to enable the operator to

descend safely.

The baby Wright used at the Belmont Park (N. Y.) aviation

meet in the fall of 1910, had a plane length of 19 feet 6 inches,

and an extreme breadth of 21 feet 6 inches, with a total surface

area of 146 square feet. It was equipped with a new Wright

8-cylinder motor of 60 h. p., and two Wright propellers of 8

feet 6 inches diameter and 500 r. p. m. It was easily the fastest

machine at the meet. After the tests, Wilbur Wright said:

"It is our intention to put together a machine with specially

designed propellers, specially designed gears and a motor which

will give us 65 horsepower at least. We will then be able,

after some experimental work we are doing now, to send forth

a machine that will make a new speed record."

In the new Wright machines the front elevating planes for

up-and-down control have been eliminated, and the movements

of the apparatus are now regulated solely by the rear, or



A Powerful Light Motor.

Another successful American aviation motor is the aeromotor,

manufactured by the Detroit Aeronautic Construction.

Aeromotors are made in four models as follows:

Model 1.--4-cylinder, 30-40 h. p., weight 200 pounds.

Model 2.--4-cylinder, (larger stroke and bore) 40-50 h. p.,

weight 225 pounds.

Model 3.--6-cylinder. 50-60 h. p., weight 210 pounds.

Model 4.--6-cylinder, 60-75 h. p., weight 275 pounds.

This motor is of the 4-cycle, vertical, water-cooled type.

Roberts Aviation Motor.

One of the successful aviation motors of American make, is

that produced by the Roberts Motor Co., of Sandusky, Ohio.

It is designed by E. W. Roberts, M. E., who was formerly

chief assistant and designer for Sir Hiram Maxim, when the

latter was making his celebrated aeronautical experiments in

England in 1894-95. This motor is made in both the 4- and

6-cylinder forms. The 4-cylinder motor weighs complete with

Bosch magneto and carbureter 165 pounds, and will develop

40 actual brake h. p. at 1,000 r. p. m., 46 h. p. at 1,200 and 52

h. p. at 1,400. The 6-cylinder weighs 220 pounds and will

develop 60 actual brake h. p. at 1,000 r. p. m., 69 h. p. at

1,200 and 78 h. p. at 1,500.

Extreme lightness has been secured by doing away with all

superfluous parts, rather than by a shaving down of materials

to a dangerous thinness. For example, there is neither an intake

or exhaust manifold on the motor. The distributing valve

forms a part of the crankcase as does the water intake, and

the gear pump. Magnalium takes the place of aluminum in

the crankcase, because it is not only lighter but stronger and

can be cast very thin. The crankshaft is 2 1/2-inch diameter

with a 2 1/4-inch hole, and while it would be strong enough in

ordinary 40 per cent carbon steel it is made of steel twice the

strength of that customarily employed. Similar care has been

exercised on other parts and the result is a motor weighing 4

pounds per h. p.

The Rinek Motor.

The Rinek aviation motor, constructed by the Rinek Aero

Mfg. Co., of Easton, Pa., is another that is meeting with favor

among aviators. Type B-8 is an 8-cylinder motor, the cylinders

being set at right angles, on a V-shaped crank case. It is water

cooled, develops 50-60 h. p., the minimum at 1,220 r. p. m., and

weighs 280 pounds with all accessories. Type B-4, a 4-cylinder

motor, develops 30 h. p. at 1,800 r. p. m., and weighs 130 pounds

complete. The cylinders in both motors are made of cast iron

with copper water jackets.

The Overhead Camshaft Boulevard.

The overhead camshaft Boulevard is still another form of

aviation motor which has been favorably received. This is

the product of the Boulevard Engine Co., of St. Louis. It is

made with 4 and 8 cylinders. The former develops 30-35 h. p.

at 1,200 r. p. m., and weighs 130 pounds. The 8-cylinder motor

gives 60-70 h. p. at 1,200 r. p. m., and weighs 200 pounds.

Simplicity of construction is the main feature of this motor,

especially in the manipulation of the valves.