Before describing the exploits of the airmen in actual campaign let us consider some account of how they were trained for their arduous and novel duties.
To the non-professional an amazing thing about the employment of aircraft in war has been the rapidity with which pilots are trained. The average layman would think that to learn the art of manœuvring an airplane with such swiftness as to evade the attacks of an enemy, and to detect precisely the proper moment and method of attacking him in turn, would require long and arduous practice in the air. But as we have seen in earlier chapters, inventors like the Wrights, Bleriot, and Farman learned to fly with but a few hours spent in the air, with flights lasting less than ten minutes each. So too the army aviators spent but little time aloft, though their course of instruction covered in all a period of about four months.
Some account of the method of instruction as reported by several out of the hundred or more American boys who went to fly for France may be interesting.
As a rule the aviators were from twenty to twenty-five years of age. "Below twenty boys are too rash; above twenty-five they are too prudent," said a sententious French aviator. A slight knowledge of motors such as would be obtained from familiarity with automobiles was a marked advantage at the start, for the first task of the novice was to make himself familiar with every type of airplane engine. The army pilot in all the armies was the aristocrat of the service. Mechanics kept his motor in shape, and helpers housed, cleaned, and brought forth his machine for action. But while all but the actual piloting and fighting was spared him, there was always the possibility of his making an untimely landing back of the enemy's lines with an engine that would not work. To prepare for such an emergency he was taught all the intricacies of motor construction, so that he might speedily correct any minor fault.
In our army, and indeed in all others, applicants for appointment to the aviation corps were subjected to scientific tests of their nerves, and their mental and physical alertness. How they would react to the sudden explosion of a shell near their ears, how long it took the candidate to respond to a sudden call for action, how swiftly he reacted to a sensation of touch were all tested and measured by delicate electric apparatus. A standard was fixed, failing to attain which, the applicant was rejected. The practical effect might be to determine how long after suddenly discovering a masked machine gun a given candidate would take before taking the action necessary to avoid its fire. Or how quickly would he pull the lever necessary to guard against a sudden gust of wind. To the layman it would appear that problems of this sort could only be solved in the presence of the actual attack, but science, which enables artillerists to destroy a little village beyond the hills which they never see, was able to devise instruments to answer these questions in the quiet of the laboratory.
One of the best known flying schools of the French army was at Pau, where on broad level plains were, in 1917, four separate camps for aviators, each with its group of hangars for the machines, its repair shops, and with a tall wireless tower upstanding in the midst for the daily war news from Paris. On these plains the Wright Brothers had made some of their earliest French flights. A little red barn which they had made their workshop was still standing there when war suddenly turned the spot into a flying school often with as many as five thousand pupils in attendance. "To-day that little red barn," writes Carroll Dana Winslow, one of the Americans who went to fly for France, "stands as a monument to American stupidity, for when we allowed the Wrights to go abroad to perfect their ideas instead of aiding them to carry on their work at home we lost a golden opportunity. Now the United States which gave to the world the first practical airplane is the least advanced in this all-important science."
Arrived at the school the tyro studies the fundamentals of flying in the classroom and on the field for two months before he is allowed to go up—to receive as they express it, his baptême de l'air. He picks motors to pieces, and puts them together, he learns the principles of airplane construction, and can discourse on such topics as the angle of attack of the cellule, the incidence of the wings, and the carrying power of the tail-plane. More than any other science aviation has a vocabulary of its own, and a peculiarly cosmopolitan one drawn from all tongues, but with the French predominating. America gave the airplane to France, but France has given the science its terminology.
The maps of the battlefields of this war are the marvels of military science. Made from the air they show every road and watercourse, every ditch and gully, every patch of woodland, every farmhouse, church, or stonewall. Much of the early work of the aviator is in learning to make such maps, both by sketches and by the employment of the camera. It is no easy task. From an airplane one thousand feet up the earth seems to be all a dead level. Slight hills, gentle elevations, offer no contrast to the general plain. A road is not easy to tell from a trench. All these things the aviator must first learn to see with accuracy, and then to depict on his map with precision. He must learn furthermore to read the maps of his fellows—a task presupposing some knowledge of how they had been made. He must learn to fly by a map, to recognize objects by the technical signs upon it, to estimate his drift before the wind because of which the machine moves sidewise en crabe—or like a crab as the French phrase it.
His first flight the novice makes in a machine especially fitted for instruction. The levers are fitted with double handles so that both learner and tutor may hold them at once. If the greenhorn pushes when he should pull the veteran's grip is hard on the handle to correct the error before it can cost two lives—for in the air there is little time to experiment. Either set of controls will steer the machine. The pupil grasps his levers, and puts his feet on the pedals. At first the instructor will do the steering, the pupil following with hands and feet as the motions made by the instructor are communicated to him by the moving levers. For a time the two work together. Then as the instructor senses that the student himself is doing the right thing he gradually lessens his own activity, until after a few days' practice the student finds that he is flying with a passenger and directing the machine himself. In France, at any rate, they teach in brief lessons. Each flight for instruction is limited to about five minutes. At first the student operates in a "penguin"—a machine which will run swiftly along the ground but cannot rise. It is no easy trick at first, to control the "penguin" and keep its course direct. Then he will try the "jumps" in a machine that leaps into the air and descends automatically after a twenty to forty yards' flight. As Darius Green expressed it so long ago, the trouble about flying comes when you want to alight. That holds as true to-day with the most perfect airplanes, as in boyhood days when one jumped from the barn in perfect confidence that the family umbrella would serve as a parachute. To alight with an airplane the pilot—supposing his descent to be voluntary and not compelled by accident or otherwise—surveys the country about him for a level field, big and clear enough for the machine to run off its momentum in a run of perhaps two hundred yards on its wheels. Then he gets up a good rate of speed, points the nose of the 'plane down at a sharp angle to the ground, cuts off the engine, and glides. The angle of the fall must be great enough for the force of gravity to keep up the speed. There is a minimum speed at which an airplane will remain subject to control. Loss of speed—"perte de vitesse," as the French call it—is the aviator's most common peril in landing. If it occurs after his engine is cut off and he has not the time to start it again, the machine tilts and slides down sideways. If it occurs higher up a vrille is the probable result. In this the plane plunges toward the ground spinning round and round with the corner of one wing as a pivot. In either case a serious accident is almost inevitable.
In fact the land is almost as dangerous to the navigator of the air as it is to him of the sea. To make good landings is an art only perfected by constant practice. To shut off the engine at precisely the right moment, to choose an angle of descent that will secure the greatest speed and at the same moment bring you to your landing place, to change at the most favourable time from this angle to one that will bring you to the ground at the most gentle of obtuse angles, and to let your machine, weighing perhaps a ton, drop as lightly as a bird and run along the earth for several hundred feet before coming to a full stop, are all features of making a landing which the aviator has to master.