AIRSHIPS of the rigid or Zeppelin type have been the subject of much conjecture by both naval officers and the general public as to whether they really offer any military features which warrant their development as potential weapons of war. The Bureau of Aeronautics in championing the development of this type of aircraft has come in for considerable criticism in the Navy itself for wasting time and money on what most people believe to be a worthless cause. This article is an attempt to analyze, briefly and impartially, the probable future military value of this type of aircraft, and is based on about ten years’ experience with this and smaller types of airships.
Already much has been written in defense of airships, but generally from a partisan standpoint and based on their use in the late war and what various high authorities had to say about them. The tendency of the advocates and defenders has been to emphasize good points and slur over weak ones, as will always be true in the case of a controversial question. In taking up the case for or against the airship, we might as well eliminate in the beginning all performances of present-day and past airships and admit frankly that these ships possess no military characteristics which, in view of their cost, would warrant their survival. The Navy has a limited amount of money to spend on aviation and it must be spent wisely. Recent developments in heavier-than-air craft and prospects of future performance require great improvements in the rigid airship if it is to survive as a military weapon.
What does the future hold for this type of aircraft? The Navy is now building two ships, each double the size of the Los Angeles. These ships are hailed as airplane carriers in addition to their supposed value as scouts. They will have a total gas volume of more than 6,000,000 cubic feet, which means a gross lift of about 200 tons when inflated with helium gas. They will carry five or six small fighting planes and will have a cruising radius of 7,000 miles at fifty knots speed. This is a paper calculation and, while technically accurate, is not apt to be reached in practice, due to the numerous factors that enter into the practical operation of airships and which prevent calculated performances from being reached except on special flights under perfect conditions.
These ships are conventional in design except for greatly improved strength features and provisions for carrying planes. Undoubtedly they will be a great improvement both in safety and performance over any present-day ship, if we neglect the two ships now building in England and not yet tested. It is not believed, however, that these two ships will add any appreciable strength to the military efficiency of the Navy, and for the very simple reason that two ships are not enough. Experimentally, yes, but not practically. The great potential value of aircraft for scouting purposes is the release of surface craft from some of these duties.
The Navy would require at least twenty large airships in a major operation if they are to fulfill their proper function. Where are these ships to be obtained? There is but one answer to this question—from a civil reserve consisting of transoceanic passenger and express airships. The Navy will never have money enough to develop a proper airship service, but the money spent on airship development will not be wasted if by its efforts the Navy proves the practicability of these ships for passenger-carrying and maintains in its service the nucleus of a real airship service in time of war with a few bases strategically located.
For years airship designers and pilots have looked forward to a 10,000,000-cubic- foot airship. It is logical to expect this as the next step in development. It is also logical to rate this sized ship as a standard both for military and civil purposes. An airship’s useful load increases directly as the volume, wherein lies its great advantage over the plane as a weight or passenger carrier over great distances. It is admitted that the airship is cumbersome to handle on the ground and that it is fragile under these circumstances, but so will be the large multiengined plane if it ever develops successfully.
Let us picture our standard ship. In the first place we will get away from the use of only helium gas and from the use of gasoline. The 10,000,000-cubic-foot ship will have most probably a gas-tight cover of dural metal with a seal of helium gas inside the shell around central gas bags of hydrogen which will permit a better and more economical performance than an all-helium ship, with almost the same safety. It will use heavy oil for its motors or perhaps a gas such as the Blau gas used by the Graf Zeppelin. It is not improbable that it may burn hydrogen as a fuel. Its engines will give it a speed of well over 100 miles per hour, and it will be able to do 10,000 miles and carry in addition about 100 tons of passengers and express. Its crew will be about the same as the present type of ship with the addition of servants for the passengers. The above figures are only approximate, but are not unduly optimistic. They are given merely as a rough estimate of what may be expected from the airship of the future in the way of strictly commercial performance.
Let us consider the military value of such a ship or of a squadron of these ships which might be available to the Navy in time of war. Their size, carrying capacity, speed, and cruising radius suggest many auxiliary uses to which they might be put. As scouts their use may be limited somewhat to areas not in control of enemy air forces, but all other scouts except submarines will be very vulnerable to air attack in the next war whenever in the vicinity of an area of enemy air concentration. It is also quite possible for an airship to make observations from above the visibility ceiling, by lowering an observer in a towing egg connected by telephone with the control car. This was the German system for directing bombing raids from clouds or high altitudes. It is also quite possible to refuel at sea from surface aircraft carriers or other ships and so continue at sea indefinitely. A sufficient number of these ships could therefore render a most efficient scouting service either accompanying a fleet or from shore stations.
For convoying or guarding convoy routes, they can render invaluable service so far as the early detection of raiding surface ships is concerned. This is a service which they and the smaller nonrigid airships actually did render in the World War. Airships are superior in this respect to planes due to their ability to fly at any desired speed and conform their movements and speed to that of the convoy.
There are many difficulties to be overcome before an actual aircraft carrier can be developed from an airship. To carry five or six fighting planes for protection and as supplementary scouts is a simple problem. It is merely a question of how much weight can be released with safety without any means of compensating for it other than loss of gas. The tendency of nontechnical airship advocates to speak glibly of carrying and releasing dozens of planes is to be deplored, as most of these statements are made by people who should know better.
A fighting plane weighs about 3,000 pounds. To release ten such planes means an immediate change in lift of 30,000 pounds or fifteen tons. This is a rather large fish for even a 10,000,000-cubic-foot ship to disgorge at once, and to be effective as an airplane carrier more than this number of planes should be carried. It is quite feasible to carry enough planes for protection and supplementary scouting, and perhaps this is all we should look for in the airship of the near future.
The difficulties in handling airships have been rather magnified in the past due to unavoidable causes, not the least of which has been the absolute necessity of conserving the few ships that have been in existence. Money has also been lacking for the rather costly experiments necessary to develop safe mechanical means of handling. Much progress has been made in the past year or so at Lakehurst in this respect as money has become available to develop handling cars and the like which have long been desired. The Germans in their many years of airship building and experimentation did not stress mechanical methods, as man power was always available to them in the shape of soldier garrisons. It remained for the English to invent the mooring mast, which has now been improved. In the future it is quite probable that the large ships will be handled and kept up by a much smaller force than is now required for the small ships of today. The mobile mast on a ship was the result of the projected flight of the Shenandoah to the north pole, though it was first suggested by the writer in the winter of 1921 as a possible use for some of the ships which were selected for retirement by the Conference on the Limitation of Armaments.
The mooring mast, whether of temporary or permanent character, will be of great assistance to airship operations, especially for military uses, but masts cannot take the place of sheds, and any commercial proposition must take into consideration the expense of terminals, repair sheds, and that which corresponds roughly to docking facilities for surface ships, at least at the main terminals of the lines.
These terminals on United States soil, whether publicly or privately owned, would of course be available to the Navy in war time if the ships were taken over and, when supplemented by temporary masts in strategic locations, would provide an airship organization capable of quick mobilization and military use. It would seem, therefore, that we should, through the agency of the Navy Department and Congress, encourage the development of transoceanic airship lines under American registry and with American capital. The crews of these ships should be part of our naval reserves and every encouragement should be given to capital in the way of mail contracts, terminals, and the like, that the civil government is able to give.
The answer, therefore, seems to be that the military value of airships, while easily demonstrable, will depend in our case on the development of a civil airship service ^ strong enough to compete with that of other nations and to develop a national personnel for their operation. The conversion of these passenger ships for military purposes need not be a complicated or lengthy operation, as the airship will never be primarily an offensive war machine.