Bore stars—illumination of all gems!
Such were his holiday fancies, seldom revealed, even to his associates. The public had no intimate part in his project. A few trusted engineers, eminent in their profession, and a few financiers, formed his advisory board. For two years he worked on the structural elements of the great sails, propellers, and framing of his ship. But unhappily when he was preparing to present his final plans to his council of engineers, before building the large vessel, he was brought suddenly to the close of his career.[39]
Mattullath’s proposed air ship consisted of two parallel torpedo-shaped hulls sustained by superposed plane or slightly arched surfaces, and propelled by feathering-paddle disk wheels embedded in the planes; the engines, cargo and passengers to be placed within the hulls.[40] This arrangement would enhance the comfort of the passengers at high speeds, eliminate resistance, distribute the load on the framing, and increase the moment of inertia of the vessel, thereby rendering it less sensitive to side gusts. To improve the projectile stability and steadiness, the centroid was placed as high as practicable. Large steering planes were used fore and aft on both sides of the vessel, whose inclination could be changed independently, to turn the ship about its longitudinal or transverse axis. A vertical rear rudder steered to right or left, in conjunction with the side planes. All the posts were of double wedge shape; all the planes were canvassed above and below to shield the framing, after the style of Maxim. The hulls, the posts, the planes, all parts, were keenly sharpened to economize power. The ship was to run over its smooth launching field till it acquired a rising speed of forty to fifty miles an hour, then continue accelerating up to velocities sufficient for competition with passenger trains in all weather.
While one may easily point out certain questionable features in Mattullath’s project, as for example, its odd propellers, one can not so easily estimate its true merits. The torsion wing device for lateral control and steering, which he claimed in his patent application, abandoned after his death, now constitutes a very important feature of every flying machine. His planes for fore and aft control, introduced by Maxim, are also in general use to-day. The principle of load distribution, which he greatly prized for diminishing stress and adding stability, has still to be evaluated by practical test in larger craft than any now in operation. The closed hull, for comfort and economy at high speed, is at present popular with many designers.
One tentative assumption of Mattullath’s, made on the authority of Maxim and Langley, was that the friction of the air is a negligible part of the entire resistance encountered by the hull, framing and sail surfaces. Accepting their experimental conclusion, he designed a flyer so sharp and smooth in all its parts as practically to eliminate the pressural, or head resistance. With no skin friction, with scant hull and frame resistance, he could afford[41] to fly at a very slight angle, thus minimizing the drift, or wing resistance, while at the same time securing abundant lift by rapidity of flight. He thus arrived, by cold deduction from the data of those prominent experimentalists, at an aëroplane swift as the albatross, and wondrously economical of power. But his financiers were loath to gamble on that assumption. He therefore, at their suggestion, instigated systematic measurements of air friction on smooth surfaces, which demonstrated that in a sharp aëroplane flying at a very slight angle, the skin friction is nearly equal to all the other resistances combined. These results were obtained and published[42] some months after his death. They were unfavorable to his project, and to all projects for attaining high speed through the air by excessive sharpening of the vehicle.
The first dynamic aëroplane of adequate stability and power to carry a man in prolonged flight, was that of Professor Langley. This machine was nearly a duplicate, on a four-fold scale, of the gasoline model previously described, which had flown many times with good inherent equilibrium. There was accordingly every reason to expect that, weighted and launched like the model, it would fly with the same poise and swiftness, even if left to govern itself. Having in addition a living pilot, provided with rudders for steering and balancing, together with adequate fuel for a long journey, it seemed to promise still better results than the model. But an unfortunate accident in the launching so crippled this carefully designed craft that it fell down helpless, without a chance to exhibit its powers of sustentation and balance, even for a moment, in normal flight.
The first trial occurred on September 7, 1903, in the middle of the Potomac River at Widewater, Va. The aëroplane was placed on the same catapult, above the boat, that had previously started the models on their smooth and rapid maneuvers. The pilot took his seat, and started the 50-horse-power engine which ran the propellers without appreciable vibration. Tugs and launches were placed along the course where they might be of service. Photographers, on the water and along shore, were ready to furnish important pictorial records of the experiment. The aëroplane was released and sped along the track attaining sufficient headway for normal flight; but at the end of the rails it was jerked violently down at the front, and plunged headlong into the river, sinking beneath the waves. Buoyed up by its floats, it quickly rose to the surface, with its intrepid pilot uninjured, and with little damage to the structure.
As revealed by an examination of the catapult and photographs, the guy post that strengthened the front pair of wings had caught in the launching ways, and bent so much that those wings lost all support. The aëroplane, therefore, had not been set free in the air, but had been wrenched and jerked downward. Thus the launching proved nothing of the propulsive or sailing powers of the machine.
Those who understand the principles of aviation can judge the merit of Langley’s “aërodrome”[43] from its mechanical description. As shown in [Plate XVIII], it was a tandem monoplane driven by twin screws amidships. The pilot seated in the little boat could control the poise and course by several devices; he could shift his weight longitudinally 4.5 feet, laterally 2.5 feet; he could elevate and depress the rear double rudder, which when untouched ensured steady longitudinal poise, on the principle introduced by Penaud; he could steer to right and left by turning about its vertical axis, the wind-vane rudder shown below and rearward of the boat. The lines of lift, propeller thrust and forward resistance passed through the centroid, or near it, thus providing for projectile and gravitational stability. In this feature Langley’s “aërodrome” far surpassed those of his immediate predecessors, whose machines, by reason of their low centroid, possessed the stability of a pendulum, rather than that of a dart, or swallow. These various devices combined should give the craft better control in free flight than that possessed by any of the models, which had flown successfully many times in moderate weather.
If the projectile and steering qualities of Langley’s machine surpassed those of its predecessors, the propelling mechanism was a still greater advance in the art of aviation. The gasoline engine was a marvel of lightness, power, endurance and smoothness of running. It weighed, without accessories, 125 pounds, and developed 52.4 horse power in actual test at a speed of 930 revolutions a minute. With all accessories, including radiator, cooling water, pump, tanks, carburetor, spark coil and batteries, it weighed 200 pounds, or scarcely five pounds per horse power—a great achievement for that time. It could run many hours continuously under full load, consuming about one pound of gasoline per horse power per hour. Its five cylinders, arranged radially round a single crank shaft, were made of steel lined with cast iron, and measured 5 inches in diameter by 5.5 inches in stroke. Its running balance was excellent. By means of bevel gears it drove the twin screws at 700 revolutions per minute, giving a thrust of 480 pounds, the screws being very nearly true helices of unit pitch ratio and 30° width of blade, carefully formed of three radial arms covered with canvas.