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 Wright 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 538square feet. Now, by using a specially designed motor of 65h. 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 supporting 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 8feet 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 "tail"control.
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 52h. 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 4pounds 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.
