Machines do not all land at the same speed. The famous Morane monoplane skimmed along the ground at anywhere from 45 to 90 miles an hour. It is manifestly impossible to do more than suggest the fundamental principles of aeroplane flight here. To be sure, the type of aircraft has, as we have indicated, much to do with why and how it flies. Because of its similarity to the bird and owing to the lack of struts, etc., to increase the head resistance the monoplane or single-wing plane is the fastest machine. The absence of struts and the few bracing wires brings a greater strain on the wings and increases its chances of breaking. The biplane, with its two parallel wings separated by struts, is more easily braced and proportionately stronger. The lift is also greater, due to the additional wing surface. The vacuum made over the lower wing is interfered with by the upper plane, and thus neutralizes somewhat the lifting and flying efficiency of the upper wing. Since a plane must reverse all its stresses when looping, the double supports of the biplane make it less susceptible to doubling up and falling. These are some of the reasons for the popularity of the biplane.
The triplane is so called because it has three tiers of wing surfaces set one above the other. This allows for even greater strength in construction, and despite the resistance several very fast-climbing triplanes have been built. The famous Caproni triplanes with three motors have a wing spread of 127 feet. Many biplanes and flying-boats also have approximately 126-foot wing spread. The well-known Handley Page bomber and the NC-1, NC-2, NC-3, NC-4 Naval Flying Boats, which tried the Atlantic flight, had a similar wing spread.
In the war the small aeroplane of the monoplane or biplane type with a small wing spread and equipped with a rotary motor, whose nine or more cylinders revolved with the propeller, or a small V-type motor, was called a scout. These biplanes seldom had a wing spread of over 28 feet and the horse-power of the rotary motors seldom developed more than 150 horse-power, whereas the stationary motors for these same machines generated as much as 300 horse-power, as in the case of the Hispano-Suiza. These machines were used for fighting because they made as high as 150 miles an hour and responded so easily to the slightest movement of the “joy stick” and, consequently, manœuvred so readily. Since trick flying was absolutely essential to air duels these machines were best for this purpose and for quickly getting information of troop movements.
The next larger size, seating two men and driven by the same types of motors or even larger twelve-cylinder Rolls-Royce or Liberty motors, but with a wing spread of from 34 to 48 feet, was used for taking photographs, directing artillery-fire, and general reconnaissance in war. The multimotored machines, with a wing spread of anywhere from 48 to 150 feet, were used for bombing at night or during the day. Owing to the size of these machines and because of their slow-flying speed they were easy to land. Some of the scouts weighed, with petrol and two hours’ fuel, less than 1,000 pounds, whereas the four-motored bombers, with 127-foot wing spread, weighed over six tons and could carry a useful load of three tons.
The hydroaeroplane does not differ fundamentally from the aeroplane as regards flying principles. In structure it may be a biplane or triplane, but owing to the supports necessary to carry the pontoons it cannot be easily attached to a monoplane. Structurally, it differs from the aeroplane only in having pontoons or a boat substituted for wheels and landing chassis. Owing to the surfaces presented by the pontoons or the hull of the boat, looping is practically eliminated and the spread of these flying craft is much slower than land machines.
Although M. Fabre conducted experiments with aeroplanes carrying floats instead of wheels, Mr. Glenn H. Curtiss was the first to successfully construct and fly a hydroplane. At the time of his flight down the Hudson River from Albany to New York he equipped his plane with a light boat to protect himself in case of a forced landing on the water. Encouraged by this experiment under the Alexander Graham Bell Aerial Experiment Association, and by later attaching a canoe, he succeeded in landing and getting off the water. Later he built a hydroaeroplane and flew successfully at San Diego, Cal., thus establishing America as the land which invented and developed the seaplane and flying-boat.
Structurally, the modern seaplane has two small pontoons on the end of each wing and a small boat in the centre, or sometimes only two pontoons in all which are side by side near the fuselage. The flying-boat has one large boat instead of a fuselage, with a small pontoon on the end of each wing. The former is used for fast flying, but owing to the air resistance to the pontoons, and especially to the boats, the speed cannot be compared to that of the scout aeroplanes. Moreover, they are much harder to do stunts with and few are known to have looped the loop. Like the big land bombers the flying-boats may be equipped with as many as three motors. One of these has carried as many as fifty passengers at one time.
Contrary to the accepted notion, these flying-boats are very hard to land on the sea because it is so difficult to calculate the position of the wave when you strike—both are moving so rapidly.
As we have already seen that due to the fact that a heavier-than-air machine must be moving at least 35 miles an hour to get off the ground or water, a strong and powerful motor is absolutely essential to make aeroplane flying possible. We have already discovered that the Wrights had to construct their own motor because none was light enough for an aeroplane. Their 16 horse-power single-cylinder engine weighed over 200 pounds. To-day the Liberty is rated at from 400 to 450 horse-power, and it weighs less than two pounds per horse-power. An Italian aeronautical engine develops 700 horse-power, and one sixteen-cylinder American motor generates 900 horse-power. This shows the tremendous development of the motor for modern flying.
