If, however, B were equipped with an astern gun the aeroplane Awould be within the fire of B when the forward gun of the latter could not be used. Similarly if A were also fitted with an astern gun it would be able to attack its pursuer the whole time B was to its rear and in this event, if its gun-fire were superior, it would be able to keep the latter to a safe distance, or compel B to manoeuvre into a superior position, which would entail a certain loss of time.
An astern firing gun would be valuable to B in another sense.
Directly it had passed A or brought the latter within the zone of its astern gun it could maintain its fire at the most advantageous range, because owing to its speed it would be able to dictate the distance over which shots should be exchanged and if mounted with a superior weapon would be able to keep beyond the range of A's guns while at the same time it would keep Awithin range of its own gun and consequently rake the latter. In the interests of self-preservation A would be compelled to change its course; in fact, B would be able to drive it in any direction he desired, as he would command A's movements by gun-fire.
The value of combined ahead and astern firing has been appreciated, but there is one difficulty which at the moment appears to be insuperable the clearance of the propeller. At the moment astern-firing, if such it may be called, is maintained by repeating rifles, but this armament is not to be compared with machine-gun firing, as the latter with its capacity to pour 400to 600 shots a minute, is far more deadly, particularly when the weapon is manipulated by a crack gunner.
Up to the present the offensive armament of aeroplanes has been confined to light machine guns such as the Hotchkiss, Berthier, Schwartlose, and Maxim weapons. So far as the arming of aeroplanes is concerned the indispensable condition is light weight. With airships this factor is not so vital, the result being that some dirigibles are mounted with guns, throwing one pound bursting shells, fitted either with delay action or percussion fuses, the former for preference. These shells are given a wide cone of dispersion. Experiments are also being made with a gun similar to the pom-pom which proved so useful in South Africa, the gun throwing small shells varying from four to eight ounces in weight at high velocity and in rapid succession. While such missiles would not be likely to inflict appreciable damage upon an armoured aeroplane, they would nevertheless be disconcerting to the aviators subjected to such fire, and in aerial combats the successful undermining of the adversary's moral is of far greater importance than in land operations, since immediately ascendancy in the artillery operations is attained the final issue is a matter of moments.
But the most devastating arm which has yet been contrived for aerial operations is the light machine gun which has recently been perfected. The one objective with this weapon is to disable the hostile aircraft's machinery. It fires an armour piercing projectile which, striking the motor of any aircraft, would instantly put the latter out of action. The shell has a diameter of about .75 inch and weighs about four ounces. The gun is a hybrid of the mitrailleuse and the French "Soixante-quinze,"combining the firing rapidity of the former with the recoil mechanism of the latter. This missile has established its ability to penetrate the defensive armouring of any aeroplane and the motor of the machine at 1,000 yards' range. This offensive arm is now being manufactured, so that it is likely to be seen in the near future as the main armament of aeroplanes.
At the moment widespread efforts are being made in the direction of increasing the offensive efficiency of aircraft. It is one of the phases of ingenuity which has been stimulated into activity as a result of the war.
