It may be agreed, in this connection, that the airship would, in a number of cases, allow of a more detailed reconnaissance being made than from an aeroplane; its slower speed, and the fact that it could hover over one spot, would give it this advantage. But, to set against this, there is one very obvious disadvantage. The size of the airship, and the fact that it is moving slowly, makes it an admirable target for artillery. In actual warfare, it would, without doubt, very soon be hit.
In this connection, too, the fact must be remembered that, whereas a wrecked aeroplane would represent a comparatively small financial loss, the destruction of a dirigible would be as great a calamity as the loss of a whole aeroplane fleet.
The expenses entailed in organising a dirigible balloon fleet are enormous, and altogether out of proportion to the useful work which these vessels could accomplish in time of war.
If an airship service is to be of practical value, monster sheds must be erected all over the country, so that a vessel may be able to run to one or other of them for shelter, when caught in a high wind. Apart from the expenditure which these sheds entail, the need arises to spend other large amounts upon the crews of trained men necessary to handle the aircraft when they leave the ground, or return from a flight.
There is another formidable item—the cost of the hydrogen gas necessary to inflate the huge envelopes; and, added to this, there is constant expenditure in effecting repairs, caused by the trifling accidents which are always occurring in handling these aerial monsters. Thus, a ruinous bill of cost is quickly arrived at.
And, as against all these disadvantages, the airship, as has been shown, has few, if any, definite advantages over the aeroplane. It can remain in the air longer, it is true; and it can, at the moment at any rate, carry heavier loads. But the great size of its envelope has, so far, made it the plaything of any high wind; and its bulk, in addition, renders it apparently impossible to force it through the air at anything like the speed attained by the aeroplane. Under favourable conditions, airship speeds of from thirty to thirty-five miles an hour seem to represent the best results yet attained.
Practical comparisons, between dirigible balloons and aeroplanes, were possible in the famous French manœuvres, in the autumn of 1910, which have been previously referred to. On this occasion, the aeroplanes were out, and at work in gusty winds, when the dirigibles were compelled to remain in their sheds.
And, when the airships did emerge, it was a subject of comment that, in comparison with the aeroplanes, they offered quite an easy mark for gun-fire.
This fact must be remembered, also. In actual warfare, the dirigible balloon would, inevitably, fall a prey to an attack by aeroplane. Aided by their greater speed, and by the fact that they could probably approach quite near to a dirigible without being seen, aeroplanes would be able to rise above its gas-containing envelope, and wreck the craft by dropping a destructive bomb.
Such points as these have, of course, weighed with the experts of Germany and France. Neither country has abandoned research work in regard to dirigibles. It is quite likely, in fact, that further improvements may be made with these machines, which will better fit them for use in warfare. But, at the present time, when any contrast of utility is made, the aeroplane is immeasurably the more practical weapon; and, whereas a limited expenditure upon experimental work with lighter-than-air machines is not to be questioned, it is to the aeroplane corps that any War Department must look for reliable, everyday service in war-time.