As the range of anti-aircraft guns increased the flyers were driven higher and higher into the air to escape their missiles. At one time 4500 feet was looked upon as a reasonably safe height, but when the war had been under way about two years the weapons designed to combat aircraft were so improved that they could send their shots effectively 10,000 feet into the air. If the aircraft had been forced to operate at that height their usefulness would have been largely destroyed, for it is obvious that for observation purposes the atmospheric haze at such a height would obscure the view and make accurate mapping of the enemy's position impossible. For offensive purposes too the airplanes at so great an elevation would be heavily handicapped, if not indeed rendered impotent. As we shall see later, dropping a bomb from a swiftly moving airplane upon a target is no easy task. It never falls direct but partakes of the motion of the plane. It is estimated that for every thousand feet of elevation a bomb will advance four hundred feet in the direction that the aircraft is moving, provided its speed is not in excess of sixty miles an hour. As a result marksmanship at a height of more than five thousand feet is practically impossible.
In the main this situation is met, as all situations in war in which efficiency can only be attained at the expense of great personal danger are met, namely, by braving the danger. When the aviators have an attack in contemplation they fly low and snap their fingers at the puff balls of death as the shrapnel from their appearance when bursting may well be called. Naturally, efforts were made early in the war to lessen the danger by armouring the body of the machine sufficiently to protect the aviator and his engine--for if the aviator escaped a shot which found the engine, his plight would be almost as bad as if the missile had struck him.
The main difficulty with armouring the machines grew out of the added weight. The more efficient the armour, the less fuel could be carried and the less ammunition. If too heavily loaded the speed of the machine would be reduced and its ability to climb rapidly upon which the safety of the aviator usually depends, either in reconnaissance or fighting, would be seriously impeded. The first essays in protective armour took the form of the installation of a thin sheet of steel along the bottom of the body of the craft. This turned aside missiles from below provided the plane were not so near the ground as to receive them at the moment of their highest velocity. But it was only an unsatisfactory makeshift. At the higher altitudes it was unnecessary and in conflict with other airplanes it proved worthless, because in a battle in the air the shots of the enemy are more likely to come from above or at least from levels in the same plane. The armoured airplane was quickly found to have less chance of mounting above its enemy, because of the weight it carried, and before long the principle of protecting an airplane as a battleship is protected was abandoned, except in the case of the heavier machines intended to operate as scouts or guides to artillery, holding their flights near the earth and protected from attack from above by their attendant fleet of swift fighting machines. Of these the Vickers machine used mainly by the British is a common type. It is built throughout of steel and aluminum, and the entire fusillage is clothed with steel plating which assures protection to the two occupants from either upward or lateral fire. The sides of the body are carried up so that only the heads of the aviators are visible. But to accomplish this measure of protection for the pilot and the gunner who operates the machine gun from a seat forward of the pilot, the weight of the craft is so greatly increased that it is but little esteemed for any save the most sluggish manoeuvre.
Indeed just as aircraft, as a factor in war, have come to be more like the cavalry in the army, or the destroyers and scout cruisers in the navy, so the tendency has been to discard everything in their design that might by any possibility interfere with their speed and their ability to turn and twist, and change direction and elevation with the utmost celerity under the most difficult of conditions. It is possible that should this war run into the indefinite future we may see aircraft built on ponderous lines and heavily armoured, and performing in the air some of the functions that the British "tanks" have discharged on the battlefields. But at the end of three years of war, and at the moment when a๋rial hostilities seemed to be engaging more fully than even before the inventive genius of the nations, and the dash and skill of the fighting flyers, the tendency is all toward the light and swift machine.
[Illustration: Photo by Press Illustrating Service.
A Curtis Seaplane Leaving a Battleship.]
