by R. L. Barkley & F. D. Buckley,
PROCEEDINGS, March 1943, V.69
A study of naval warfare during the last century shows a strong tendency, in all navies, to base the essence of naval strength upon static concepts. Nearly every layman is familiar, to some extent at least, with the almost simultaneous introduction of the rifled gun and armor plate into the navies of the world, and the ensuing competition between the two for decisive superiority. Sea power then became securely shackled to the gun, to the development of which all else was subjected. The introduction of the torpedo, at nearly the same time, did not seem to create nearly the interest as did the gun, and consequently not the effort to develop protection against it, with the net result that when efficient means were first employed in large numbers for launching torpedoes, the large warships remained nearly unprotected against underwater attack. Such was the situation in 1914. A similar state of affairs, though not exactly parallel, was seen to exist when aviation began to exert influence upon sea power in the present war. The introduction of the bomb as a weapon against naval craft again caught the navies unprepared, with the result that many new protective measures had to be taken. The provision of a new and efficient means of launching torpedoes provided additional headache for the naval operators and constructors. The complication growing out of the necessity to protect the gun from other methods of attack has raised the question, in a somewhat suppressed tone of voice, whether or not it is worth the trouble. The ponderousness of naval equipment has always made the modification of it to meet new conditions, imposed by new means of attack, most difficult. It may be said that the use of aviation at sea, within the limits of its sea-keeping qualities, has replaced the gun as the primary offensive weapon. The provision of overwhelming offensive power at sea, therefore, seems to hinge upon the improvement of the sea-keeping qualities of aircraft.
No one has ever questioned the logistic axiom that all naval forces can operate most efficiently at a fairly short distance from well-equipped bases, and that their efficiency drops off as the distance from their bases is increased. This is particularly true of aircraft, for in addition to the normal difficulties which accrue to long range operation against an objective, the weight of the military load, or persuasive force, must be decreased to provide additional fuel to attain the necessary range. This is evident from the high degree of success of shore-based aviation against all types of surface craft which have ventured too far within its striking range. The fact that surface units are still able to operate in the open sea almost immune to shore based air attack demonstrates the inability of aviation to carry out effective long-range attack at sea. The Navy early realized that it would be necessary to provide some means of transportation, equipped with basing facilities, to bring aviation within a reasonable striking distance of its objective. This realization led to the development of the aircraft carrier. However, even after the carrier, and naval aviation based thereon, had achieved a high degree of efficiency, one basic misconception continued to retard the full exploitation of its offensive power. This was the belief that the function of aviation would be more or less secondary to the conduct of naval battles. Aviation was assigned the task of “gaining control of the air,” or of neutralizing the effectiveness of the naval aircraft of the enemy, while the decisive action would take place between the battle lines of the opposing fleets. Experience of the present war thus far seems to indicate that, on the contrary, aviation is the major offensive power, and hence the deciding one, and that the secondary function or limited role should be assigned to surface units. One still hears, occasionally, that the final decision in the naval warfare between ourselves and Japan will be between two great opposing battle lines, opposing aircraft strength being equal. Which in itself seems a fallacy, inasmuch as it would require the assignment of the primary offensive weapon, aviation, to the protection of something which has assumed a secondary importance. Besides, the adaptability of aircraft to mass production, in sharp contrast to the slow, laborious process of constructing heavy fighting ships, should enable us to achieve decisive superiority in this bracket much more quickly. At any rate, a somewhat different concept of the picture has been already indicated by the heavy emphasis recently laid on aircraft carriers. The announced program of 500,000 tons of new carrier construction, plus the conversion of other naval and merchant types to carriers, will enable us, it is hoped, to provide our primary offensive weapon, naval aviation, with crushing superiority.
The Pacific situation calls for a greatly expanded concept of military strategy. The factors of time and distance work intensely in favor of the side which can bring the strongest offensive to bear while maintaining a relentless stream of reinforcements. The contested territories were snatched so by the Japanese and can be retrieved in the same manner if strong aviation forces can be brought into play. The geographical panorama shows that naval warfare slightly adulterated with aerial support is but the choice forced on local commanders. The restricted waters fraught with rocks and shoals and every impediment devised by man make the business of seaborne logistics and conquest very difficult. Spice the dish with a dash of efficient aviation and the problem becomes ponderous. We must either strike the enemy at his vitals or pave the nearly bloodless road from Bouganville to Bataan with gore. The construction of carriers for such a program takes time to achieve. The urgency of obtaining this superiority advises us to thoroughly investigate all possible means for rapidly building up our hitting power. Such a means, holding great possibility, lies in the development of the rigid airship as an aircraft carrier. However, the general reputation of the rigid airship, based largely on the results of our own operation, does not lend itself to the placing of much confidence in such development. Many harmful misconceptions regarding airships have taken firm root in the public opinion-and what is more dangerous, in naval opinion as well. It is the purpose of the brief history which follows to show in some detail how several of these have gained credence and why they are erroneous. At the outbreak of World War I, the Germany Navy possessed one rigid airship. The German Army had nine, three of which were pre-war commercial rigids which were used primarily for training purposes. All of these airships had a volume of less than 1,000,000 cubic feet, which consequently limited their usefulness. The use made of the rigid by the German Army demonstrated with undeniable clarity certain limitations of the type. Its employment as a scout behind the enemy’s lines and on low altitude bombing missions in enemy territory resulted in complete and unanticipated failure. The employment of airships of small volume (rarely exceeding 1,000,000 cubic feet) to facilitate ground handling necessitated the location of operating bases close to the front lines, and permitted frequent and effective attacks on these bases by the enemy. The Army gave up the use of airships and transferred them to the Navy in 1917. The German Navy, utilizing their rigids primarily for security patrols of the North and Baltic seas, early realized that airships of larger volume would be required if their employment was to be made effective. Consequently, in 1916 the first of the so called “Super-Zeppelins” made its appearance. The first airship of this type (L-30) had a volume of 2,000,000 cubic feet and was the prototype on which mass production was organized. From the summer of 1916 through the greater part of the duration of the war, the Zeppelin Company delivered one airship of this type to the Navy every two weeks, with only three construction hangars in operation. Effective competition, giving incentive to produce better ships rapidly, was provided by the Schutte-Lanz Company which built wooden skeletoned rigid airships of similar volume and performance characteristics. Ultimately, airships of 33 per cent dead-weight tonnage, with a useful load of 45 tons, were delivered. The most spectacular employment of the German rigid was its assignment to the bombing of objectives in England. These bombing raids were the task of the airship, for at that time heavier-than-air aviation had not progressed to the stage where it could undertake them. This employment could be undertaken only because the defense against air attacks was ineffective. This was primarily due to the lack of efficient pursuit aircraft and anti-aircraft batteries. This secondary employment of the airship as an offensive weapon governed to some extent the nature of its construction. Extremely light construction was employed to enable the airship, after dropping its bombs, to climb rapidly to great heights to elude pursuing aircraft. Altitudes of 24,000 feet were obtained. At a later date, when planes had been developed sufficiently, the Germans seldom used the airship for bombing. Enemy aircraft had correspondingly improved, and the losses of airships so used increased. The airship was then forced out of an occupation for which it was by nature unsuited, but which it temporarily had been able to undertake because adequate means to combat it were not at hand. The loss of five airships during an attempted mass raid under unanticipated bad weather conditions has frequently been taken as prima facie evidence of failure of the type. Aside from being a result of poor forecasting, and perhaps also bad operational judgment, their loss was due to the inadequacy of the individual types concerned. They ran out of fuel and were carried over France by high winds, being strewn at random over the European continent. But the soundness of the airship idea can hardly be placed in jeopardy by the incident. In its primary mission, that of patrol, the German Navy made quite effective use of their airships. In going over the record, it is a little difficult to understand why the Germans never attempted to make the airship independent of the use of operating hangars by the development of mooring out facilities. Through this failure, only two airships were able to participate in the first phase of the Battle of Jutland-the most important, of course, as far as reconnaissance was concerned. These were based in the rotating hangar at Nordholz. The remainder were temporarily immobilized in operating hangars by cross hangar winds. Their nonavailability deprived Admiral Scheer of a unique advantage which would have been his under normal circumstances. The training of pilots for the rigids presented the German Navy with a perplexing problem. Post-war writings of German airship officers have stated that there were two alternatives: first, the training of officers of the regular Navy as airship pilots; second, the induction and training of pilot material from outside sources, giving them sufficient indoctrination to report correctly what they observed. The latter alternative was chosen primarily because it was considered undesirable to deprive the Navy of the services of experienced officers. However, it SOOIJ became apparent, especially at Jutland, that incorrect observations were made by airship pilots because thorough indoctrination as to the recognition of fleet types and dispositions had not been accomplished in the training period allotted. The French airship pilot, Lieutenant Commander Jean DuPlessis, commented thus on the above in his writings, “The important point is that it is especially important to educate not only good pilots, but good watch officers.” Nevertheless, some 50 airship crews were trained by the German Navy in a period of two years.
Allied reaction to the German employment of Zeppelins, both during and immediately after the war, revealed some rather peculiar quirks of psychology. Losing sight entirely of its value as a patrol and scout vessel, the allies condemned the rigid airship as a failure purely on the record of its utilization as a bombing weapon. Yet frantic efforts were made in England to copy it. Even though the plane later served the same purpose, a wholesome respect for the airship remained. This was quite evident when the United States made a reparations claim against the German government for an airship. Seven of the 14 airships remaining after the Armistice had been scuttled on the day of the Scapa Flow incident, two of which had been earmarked for delivery to the United States. When the proposition was advanced of building one large airship having a volume equal to the combined volumes of the two which had been destroyed, the Inter-Allied Control Commission decided that the ship to be built could not exceed the volume of the largest World War airship, and had to be a commercial type. The Zeppelin Works at Friedrichshafen was to be destroyed immediately upon completion of this ship, which on delivery in 1924 became the U.S.S. Los Angeles. The latter stipulation was later removed. Post-war airship history has been a series of unexplained and conspicuous failures. Only in Germany was the airship accepted and developed as a common carrier. The success of the Graf Zeppelin and Hindenburg in adhering to a strict commercial schedule, the reliability of which has never been approached by any other means of transoceanic air transportation, could quite easily have led us to the conclusion that the type was capable of simple and easy adaptation to our own commercial and military needs. The example backfired. The fact that no responsibility had been placed for any of our airship failures cast a direct aspersion on the type, and elevated the normal and quite easily attained German success to a plane on a par with the medieval black arts. The press repeatedly emphasizes that the Graf Zeppelin and Hindenburg were operated and constructed by personnel of vast experience, many of whose connections with airships pre-dated the first World War. All this was true, but it was a most misleading half truth. The effect of all this hocus-pocus had a most detrimental effect upon public-and naval-opinion. The failure of the rigid airship to make its appearance in this war on the side of Germany, though it has been reported that airships were used for cargo trips between Germany and Russia, is quite possible due to the fact that all of Germany and its controlled territory is accessible to Allied air attack. Airship bases are far more vulnerable than the airship – they can’t move. The United States, fortunately, is not so located and can make use of the intercontinental aptitude of the airship. It must be categorically stated that all major problems dealing with the construction of airships had been solved in toto prior to the embarkation on the mass production of the so-called “Super-Zeppelins” of 1916. It is just as undeniable that the rapid training of airship crews, capable of efficient operation, though perhaps with insufficient naval indoctrination, was accomplished at the same time and kept pace with the production of airships. The inherent safety of airships has been demonstrated many times, though not to the satisfaction of the ponderous committees of engineering experts assembled from time to time to investigate airship matters. A few cases will bear citation here, in some detail. In 1909, one of the early Zeppelins, LZ-5, made a forced landing damaging its bow section severely by colliding with a tree. The whole bow section, nearly up to the forward control car, was removed. Repair was accomplished by covering the open front end of the ship with envelope material, which was wired securely in place. The airship was flown back to its base. In January, 1924, the Shenandoah was carried away from a British type tower mooring mast at Lakehurst, during a severe storm. During a gust of 64 knots, the fabric covering of the upper fin was damaged. The force of the wind, working on the exposed framework of the fin, caused it to lean over to one side. This in turn steered the moored airship out of the wind direction, so that the onrushing airbody impinged not only on the bow, but on one side of the ship as well. The next gust wrenched the airship free of the mast, leaving the bow section attached thereto. Structural damage deflated the two forward gas cells. From an aerodynamic consideration, the Shenandoah’s situation was similar to that of an airship which had been making full speed, and which had suddenly stopped her engines. Although she was immediately carried backwards over the ground, she still had forward decelerating air speed. All available emergency ballast in the bow of the ship was dropped. Up elevator was applied, and the still considerable air speed was sufficient to carry the ship up to a safe operating altitude. The engines were started to assure their good operating order and immediately secured. No attempt was made to ram the damaged bow through the atmosphere. Having gained sufficient altitude, the Shenandoah was then operated as a free balloon, her air speed having decelerated to zero. No strain was being imposed upon her structure by the ·air mass of which she was now a part, though she was being carried over the ground in a northeasterly direction at nearly 60 knots. Repairs were made to the damaged structure, and after a careful inspection, the engines were started and the ship moved slowly ahead through the air. A constant watch was kept on the repaired damage, and air speed gradually increased to full speed. Nine hours after leaving Lakehurst, theShenandoah was safely docked. So concerned were those who worried at Lakehurst that an official announcement, giving up the ship as lost, was made after she had reported that conditions aboard were normal. The above incident is particularly worthy of note in that the Shenandoah, structurally fragile by comparison with the beefed-up bridge-like trusses of the Arkon and Macon, had been in operation for a period of less than four months. An improved copy of the 1916 Zeppelin L-49, which had been forced down intact in France, her structure was fabricated at the Naval Aircraft Factory at Philadelphia, erected at Lakehurst. Correct operating procedure, directed by Captain Anton F. Heinen (later Lieutenant Commander, U.S.N.R.), chief war-time test pilot for the Zeppelin Works, brought her safely through one of the worst predicaments any airship has had to face.
The following paragraph, taken from his writings, properly belongs here:
“One more misleading conception with reference to airships very generally held is the opinion that it needs super-engineering to provide at the same time, as seems to be correct at first superficial approach, extreme lightness in structure and an unheard of strength due to the idea (quite mistaken as has been shown), that it must continuously “battle the elements.” The fundamental difference between the airship and the surface vessel, where the premised condition is very real and one of the most important factors in engineering procedure, lies in the fact that this very “battle” is absent. A dramatic episode in the airship’s history, which occurred during the Shenandoah operation at Lakehurst, (there have been numerous others before), could very well illustrate the point, if we succeed in breaking through the earth-bound reportorial clamor of the daily press, which saw superskill and even heroism where there was nothing of the kind, and failed to see the real significance of the happening in spite of earnest attempts by the participants to emphasize the other side of it.”
A similar case occurred when the British airship R-33, also a copy of a 1916 Zeppelin, was carried away from the same type of mooring. Flight Lieutenant Booth brought the R-33 back to her base safely, after the ship had been carried out to sea a considerable distance. Similar procedure was followed, Lieutenant Booth himself inspecting the damaged structure as the speed of the airship was slowly increased. R-33 carried the mooring gear from the top of the mast with her.
In commercial airship history, the Graf Zeppelin , under Dr. Eckener, on her first trip to Lakehurst m 1928, suffered a casualty to the fabric of the lower surface of her port horizontal fin. Although the airship was statically heavy, she was stopped to permit repair to the 40-foot rent in her envelope. It became necessary several times to cease work to permit the heavy and falling airship to slowly regain altitude by careful use of the engines. Here again the press went overboard on sensationalism, praising the conduct of Knute Eckener, son of the Graf’s skipper, in effecting the repair.
It is the intended purpose of the above examples to show, insofar as it is possible without trespassing on the ground of officially closed investigations, that when sound operating procedure complements the inherent safety of the airship, no other means of transport can exceed its reliability. Had the airship been lost in any of these cases, an investigation could quite properly have ascribed the loss to “100 per cent pilot failure.”
To attempt to lay down precise casualty procedure for airships is futile, as each case presents different circumstances for which the operator must prescribe the correct course of action. There is one cardinal rule, however, which must never be violated: In the event of any reported damage to structure or to the outer cover, stop immediately. This is as mandatory in all respects as the submarine rule: Never dive with a hatch open. It has been violated with fatal results.
This ability of the airship to stop and remain motionless, completely surrounded by the medium in which it operates, removes all dynamic strain from its structure. It is a safety feature which is always present, the importance of which cannot be overemphasized. It is the only air vessel so favored, other than the free balloon.
The successful airship operator became, in the eyes of the press at least, a near god whose highly specialized duties required undivided attention. This superskill was assumed to exist to some extent in our own airship organization. The opinion became so widely held here that the Navy was openly and severely criticized in the press for insisting upon the rotation of duties of qualified airship officers. This attitude persists even today, and was evidenced in the August 3 issue ofTime magazine which caustically criticized the Navy Department for sending an experienced airship officer to sea.
It would seem from the little the press knows about lighter-than-air (or naval affairs, for that matter) as evidenced by the many articles containing sad distortions of fundamental operating ‘truths, that it is in a poor position to criticize, especially when it introduces pointless and irrelevant polemics. The French airship pilot, Lieutenant Commander DuPlessis, commented thus on the expert opinion of the press:
“Press opinion, no matter what that might be, has no influence on the actual waging of war, and when it does influence operations it does so generally to lead the armies to disaster.”
Even under the pressure of war, the press today does not admit the advisability of military matters being decided by professional soldiers and sailors. The airship, if it is to be successful as a naval tool, must have its development and activity directed by naval officers, whose general knowledge of the whole picture into which it fits will enable them to properly correlate its functions. Overspecialization of airship personnel tends to diminish their necessary grasp of the general picture.
After the failure of the Akron and Macon, considerable conjecture was bandied about that we had attempted too large a jump in volume. It was pointed out that they were nearly twice the volume of the Graf Zeppelin. This opinion was dispelled by the operation of the Hindenburg, which was slightly larger than either of our ships.
The Germans held a similar view prior to the close of the first World War. The largest war-time airship had a volume three times greater than that of the prewar commercial types. It was felt that the technical advances made during the war would permit the construction of small commercial types which would be much easier to handle than the larger naval airships. On commissioning the post-war commercial airship Bodensee, of the same volume as the pre-war types, it was found to the general surprise of all concerned, that the large naval airships had been much easier to operate, with the exception of ground handling.
The reason was shocking in its simplicity. Any vessel of relatively large displacement is less subject to the vagaries of the medium in which it operates, as compared to a small one. This is quite apparent to the airship student who bounces about in a small training blimp, enviously observing the relatively serene behavior of a larger patrol blimp operating in the same vicinity.
The use of the rigid airship as an aircraft carrier will require much larger volumes than have been heretofore constructed. Volumes of approximately 20,000,000 cubic feet-three times those of the Hindenburg and Akron types-are necessary to the development of efficient carriers. Such volumetric increase does not introduce any new structural or operational difficulties. It perhaps does introduce some terrifying misgivings where there is a lack of imagination. In reassurance, it is pointed out that the Hindenburg had a volume three times greater than that of the standard World War airship, which in turn was three times larger than the pre-war commercial types. According to the Hindenburg’s operators, she was far easier to operate than any previous type. As to size, such an airship would require a dimensional increase of about 50 per cent as compared to the Hindenburg, i.e., a length of 1,200 feet (Hindenburg 803 feet) and diameter of 200 feet (Hindenburg 133 feet).
The standard gross lift of such an airship (100 per cent pure hydrogen at 32°F. 29.”92 hg) would be 750 short tons. Of this, 300 tons would comprise the structural dead weight of the airship (allowing 40 per cent dead-weight tonnage). A useful load of 400 tons would be available assuming normal operating conditions of 60°F. 29.”92 hg, with 98 per cent pure hydrogen. A fuel load of 150 tons would drive the airship some 12,000 nautical miles in still air. It could carry and operate50 planes averaging 3 tons each, leaving 100 tons for aircraft fuel, bombs, etc., less the weight of the airship and aircraft crews (about 200 men) and their necessary equipment. The above estimate of performance presumes a static equilibrium take-off. Such an airship could carry (operating “heavy”) at least 5 per cent of its standard gross lift dynamically after take-off-about 40 tons in this case, and operate in that condition indefinitely. A maximum of 10 per cent of the standard gross lift can be carried dynamically for periods of a few hours. This overloading can be done by taking extra weight aboard in flight such as by fueling from another airship or landing additional aircraft. Under nearly all operating conditions a useful load of 400 tons would be available. A top speed of at least 80 knots could be expected from such an airship.
The elimination of heavy retractable landing gear installation on attached aircraft would contribute materially to the increase of their useful load. It is also probable that larger and heavier types than can be operated from surface carriers could be operated from airships.
Perhaps the greatest single advantage of the airship carrier is its adaptability to mass production. The delivery during World War I by the Zeppelin Co. of one 2,000,000-cubic foot airship every two weeks, utilizing three construction hangars, has already been pointed out. Achieving the same rate of production of airships ten times that volume demands only more facilities and men. With a dozen erection hangars in operation, the delivery of one airship carrier every four days could be realized. We have again become accustomed to rates of delivery which in normal times are startling-some of them even in view of the rather remarkable achievements of 1917-18. Shipbuilder Henry Kaiser’s recent statement that a man who knows one end of a wrench from the other can earn 95 cents per hour, that one who doesn’t will have the ends labeled for him, is typical of the daring and aggressive spirit with which the problem of mass production must be attacked. So it is with airships, in spite of the fact that a Congressional committee was recently advised that from 2 to 3 years would be required to construct a rigid airship. The German record of airship mass production need not be obscured; it is still a fact, and the possibility of improving upon it most certainly exists.
The speed and range of the airship carrier, coupled with its availability in large numbers, would make the concentration of aircraft when and where they are needed a much simpler problem than it is today. It would provide mobile bases for aircraft types which have been found to be the most effective at sea (i.e., dive bombers and torpedo planes) for much less expenditure of time, labor, and material than a similar concentration effected by surface carriers. It could and should have its construction centers located well inland, both as a defensive measure and to make use of labor which is not available to coastal shipyards. Should the airship be found only equal to the surface carrier as a base for aircraft, more attention could be diverted to the vital problem of producing cargo bottoms. It consumes some 300 tons of material as compared to 20,000 tons for a surface carrier. It is true that the material required is vitally needed in other war industries, but the development of a new and efficient aircraft carrier would most certainly establish the desirability of favoring it with a high priority classification.
The greatest objection to be held against such a proposal will be the alleged vulnerability of the airship. This criticism will become sharper as soon as it is thoroughly understood that the airship demands hydrogen to ensure continuous availability.
It is quite generally recognized in military circles that all weapons are vulnerable to countermeasures. It is also recognized that the vulnerability of any weapon is a function of the application of employment technique. It has been pointed out that the bombing Zeppelins of World War I defended themselves by making use of their great rate of climb and high operating altitude. The airship carrier will have to do practically all its operating at relatively low altitudes. Since it is acting as a transport medium rather than as a weapon itself, it must remain in the denser air of the lower altitudes in order to maintain its lift at the maximum possible value. Its defense lies in its ability to remain at a great horizontal distance from areas which are a source of danger to it. The high performance of its aircraft as compared to carrier-based types, and its relatively high speed combine to enable it to avoid attack more easily than can the surface carrier. It fears no reefs or rocks nor does it leave a betraying wake or oil slick hours behind. In an hour it moves 80 miles. In addition, it is vulnerable only to air attack, unless it should be brought by error within the range of anti-aircraft fire.
The loss of a carrier airship would involve the loss of not more than 200 men. The airship is very inexpensive with regard to the number of personnel involved to operate a given number of aircraft. The operating personnel of airships can be easily and rapidly trained. The personnel investment of a surface aircraft carrier is relatively tremendous, requiring not only personnel for the carrier but the immobilization of other units and their personnel to provide escort facilities. These units can always be advantageously employed otherwise. The greater problem is the development of proper tactical employment of the airship carrier. For this reason its operation must be constantly dominated by line aviation personnel.
The relative vulnerability of hydrogen and helium airships is an academic matter. If either were directly subject to air attack, loss would be certain. It is quite true that a single incendiary bullet can cause the loss of a hydrogen airship, but it is just as certain that if an incendiary does not cause the loss of a helium airship, means are available to do it, and would be brought into immediate action. The employment of contact bombs or explosive bullets would suffice. Special acid loaded bombs or bullets would be developed. The destruction of the airship’s lift by whatever means employed would achieve the desired result. The problem is, therefore, to avoid contact.
Contrary to press conceived belief, we do not possess sufficient helium to operate a fleet of airship carriers. According to figures released in the Army and Navy Journal of September 6, 1941, 57,000,000 cubic feet per year of helium would be required by 1944, upon completion of the 48 nonrigid airships then authorized. Authorization was being requested to bring the yearly output of helium up to 60,000,000 cubic feet. Since that time, a total of 200 blimps has been authorized by Congress. So it would not be too surprising to see even the nonrigid shift to hydrogen, assuming of course that they are delivered on time. Basing an estimate on the rather limited peace-time operation of the Akron and Macon, 60,000,000 cubic . feet per year would not suffice to operate two 20,000,000-cubic foot airship carriers. It should be noted that this hypothesis does not consider the important problem of transporting helium to airship operating bases. Scarcity of ship bottoms to transport helium, when other commodities are more urgently required, would seriously hinder the operation of airships. In railroad parlance, some 100 carloads would be required to provide initial inflation for one 20,000,000 cubic footer.
The relative lift values of helium and hydrogen are frequently misunderstood primarily because they have been frequently misrepresented. Helium, at standard conditions (100 per cent purity, 29.”92 hg, 32°F.) has 93 per cent the lift of hydrogen. In practical operation, because helium is never available at a purity greater than 97 per cent, and because of operational considerations which result in a further lowering of purity of helium relative to that of hydrogen, the lift difference is rarely less than 10 per cent. As the temperature of the air mass in which the airship operates increases, a further disparity is introduced which increases the lift advantage of hydrogen. To the 20,000,000- cubic foot aircraft carrier, structural weight and fuel load (range) remaining constant, substitution of helium means a reduction of the military load from 250 tons to 175 tons-a loss of 30 per cent. It is quite conceivable that the additional 75 tons carried by the hydrogen airship, disposed in additional aircraft, armament, or bombs, could easily mean the difference between accomplishment and failure of a mission, or even the difference between saving and losing the airship itself.
It is of interest to note here that the refusal of helium to Germany in 1938, while it resulted in the abandonment of commercial airship service, did not prevent the operation of LZ-130 (Graf Zeppelin II) for the training of new airship crews. Prior to the German attack on Russia, LZ-130 had been persistently reported in operation, carrying war materials from Russia into Germany. Even this relatively small commercial airship (same volume as Hindenburg-7,000,000 cubic feet) with range reduced to 2,000 miles, could carry better than 75 tons of payload.
During the spring of 1937, experiments were carried out involving the operation of aircraft from the Hindenburg. It was stated that mail service was to be speeded up by putting mail aboard after take-off and flying it in ahead of the airship’s arrival. Passengers were to be picked up and discharged at London by plane instead of having to go all the way to the Frankfort terminus. It is of particular interest that the plane pilot who made the tests was the late German air force general, Ernst Udet, to whom a large measure of credit is given for the organization and tactics of the Luftwaffe as well as those of the parachute troops. Although press releases and photograph captions at the time stated that Udet was the pilot, conflicting stories were told after the loss of the Hindenburg as to the results of the test-in one case a flat denial that they had ever been carried out was given to a United States naval officer. Press photographs showed that the apparatus used was practically identical to our own, except that the trapeze bar was located considerably closer to the hull of the airship. The peculiar circumstances surrounding the test give indications that it was carried out to determine the military value of the airplane-airship combination. Should Germany find herself able, through , possible defeat of Russia, for instance, to operate airships from relatively attack free bases, the airship carrier might provide means for effective attack against our industrialized east coast. The possibility should also be considered that Japan might find the combination useful to multiply her offensive naval aviation power in the Pacific and to permit attack on west coast production facilities. Japan, in cabling her regrets over our loss of the M acon, stated that she would like to investigate the usefulness of the naval airship. It is conceded that the above is largely conjecture, but it is well not to disregard it lest the airship carrier burst suddenly upon us with harsh reality. We are well aware that the Axis powers quite capably employ offensive aviation. We should become aware, if we are not already, that among them they possess the ability to operate and mass produce airships, and the willingness to expend them in large numbers, should that be necessary, to enable aviation based thereon to achieve the desired results. The problem of training plane pilots to operate from airships is quite simple, as we have found from our own experience.
During the first World War, German airships were operated exclusively from hangars. The operations of docking, undocking, and ground handling were accomplished entirely by man power. It has been previously pointed out that all but two of the German naval airships were immobilized in their operating hangars during the first day of the Battle of Jutland, and that these two were in a rotating hangar. One of the major handicaps of airship operation was thus brightly illuminated. It is surprising that the Germans took no steps to find a solution to the problem.
Similar difficulties were recognized during the operation of British anti-submarine patrol nonrigids, and a report from our Scientific Naval Attaché dated April 24, 1918, to the Chief of Naval Operations recommended that the best thought and effort be directed toward developing mooring out facilities in order to increase the service availability of patrol blimps. Today, however, a satisfactory solution remains to be developed, with the result that hangar space is still required for each and every blimp constructed. It can readily be appreciated that the difficulty of constructing operating hangars is one of the major factors responsible for the slow delivery of anti-submarine patrol blimps, which was noted in Time magazine for June 1, 1942. The situation is typical of many produced by post-war apathy towards military development.
During our operation of rigid airships, more strenuous efforts were made to overcome these difficulties. A mooring system with a great degree of reliability enabled our airships to operate for extended periods without relying upon hangar facilities. Elaborate mechanical equipment for docking and undocking was also developed, but demonstrated conclusively that an airship would always be immobilized by strong winds if forced to operate from a hangar. German commercial operators were sufficiently impressed to copy the essential features of our mooring system, which they used with great success.
The implications to be drawn from the above are quite clear: the hangar must be used only for the construction and extensive overhaul of airships. All operation must be carried out from mast bases, to assure the constant availability of the airship and the aircraft based thereon. An airship immobilized in a hangar is helpless against attack, which fact was demonstrated to the German operators during the first World War. Apparently the lesson did not penetrate.
To date, the numbers of aircraft taking part in action at sea have been small compared to those used in land operations. The primary reason for this is that there are relatively few aircraft carriers in existence. The very nature of the aircraft carrier makes it difficult to produce and replace. Hybrid conversions are being used-and should be-to augment the strength of our primary offensive power at sea, but many of these are bound to be disappointing from the standpoint of results obtained. The insufficiency of carriers seriously hampers the sea-keeping qualities of naval aircraft. Press releases have indicated that many cripples, which could have been polished off by aircraft-or fast battleships for that matter-escaped from the Battle of Midway. Sufficient aircraft of suitable types could have followed and annihilated these units, preventing their future use against us. Airship-based aircraft could have been gainfully employed here. To pursue and annihilate these forces-without the danger of being ambushed by enemy submarines. The construction of sufficient surface craft, particularly battleships, to accomplish such a task requires a formidable investment in material, time, labor, and personnel. In addition, such means are vulnerable to all the weapons of sea warfare, whereas the airship is vulnerable only to aircraft attacks. The adaptability of aircraft to mass production assures us relatively easy attainment of decisive superiority, and the rigid airship can provide basing facilities for these aircraft.
So far, results seem to indicate that the relatively short-range, carrier-based dive bombers and torpedo planes have a greater effectiveness than the long-range horizontal bomber in fulfilling the precise requirements of sea warfare. The long-range bomber is at its best employed over stationary land targets, or in the area-bombing operations now being conducted in Europe.
We must concede that the naval operations to date have been on a small scale insofar as the number of aircraft employed is concerned. Future actions will undoubtedly involve numbers greater by many times-even considering only the employment of surface carriers. But we must wait until these carriers are available before we can employ them. We have time, therefore, to undertake the development of the airship carrier. Assuming that we can equal the German rate of airship production, utilizing 12 erection hangars instead of 3, 90 airships per year could be produced, basing 4,500 aircraft averaging 3 tons each; or 2,700 averaging 5 tons each. The possibility is rather striking, but it is there nonetheless.
The fundamental concepts of sea power have not changed. The bulk of all goods and personnel necessary to the conduct of war will be transported by sea. The establishment of offensive bases, involving the so-called amphibious warfare, demands local sea control. It is not the basic concepts which have changed, but the new tools used and the means of applying them. Germany, in the older sense of the term, is not a sea power. But any military power which takes such a terrific toll of shipping, regardless of the means employed, must be considered a sea power of the highest order. The new conditions forced upon us demand a new course of action. The ponderousness of naval equipment makes its alteration to meet new conditions extremely difficult. Much of our old equipment has been made nearly useless by the new conditions under which it must fight. Insofar as possible all new equipment must be capable of adaptation to new conditions.
It is certain that aviation will remain the primary striking force at sea for some time to come, perhaps for all time. It is not necessary or desirable to introduce the additional complication of a separate air force. But a perfect liaison is necessary, and ours has improved vastly since the outbreak of the war. A clear picture of the general situation involved is the first essential-the second is the proper employment and correlation of all the offensive power at hand. How the organization is constructed is of no consequence if these two basic essentials are complied with.
As to the part the airship can play, the old conception which previously governed its development must be immediately junked. It is not a negative scout or a patrol vessel. Its aircraft do not exist only to augment its ability to scout. It is merely transportation for an offensive force of aviation, which it serves as an auxiliary with all that may imply.
The misconceptions, previously outlined, which have been permitted to arrest its development must be strenuously overridden if they continue to suppress progress, whatever their source. In the future, responsibility for operational failure must be definitely placed. Placing it on the mute airship can only frustrate the attainment of the desired development. DuPlessis, the French naval airship operator, summarized this responsibility neatly: “If, in this nice little game all responsibility evaporates, all activity is also.- destroyed and there is no equipment able to survive such a regime.” While it is quite true that the alleged difficulties of construction and operation have discouraged public opinion and to some extent naval opinion, the primary objection to the airship from a military viewpoint comes from its failure to deliver the goods when the opportunity was available. Even so, definite possibilities were indicated by the operation of the Macon.
As to construction, competition between at least two companies should be encouraged and subsidized. The competition of the smaller Schutte-Lanz airship organization was one of the major factors in the effective development of the Zeppelin airship. Contracting for the first 27 of the 48 originally authorized blimps from one company has been a second factor responsible for their slow rate of delivery. The Army, in ordering barrage balloons, contracted with at least five different companies, at greater cost perhaps, but the production has been gratifying. A blimp is, after all, nothing more than an enlarged barrage balloon provided with power and control facilities. If necessary, the Navy might provide competition by entering upon the construction of rigid airships itself, as it did in the case of the Shenandoah. The airship is not such a mysterious construction problem that it requires the monopolized services of a single, highly specialized construction company.
Nor does it require a monopoly of highly specialized operators possessing superskill. Press contention notwithstanding, the past history of airship operation amply confirms this fact. The responsibility for development falls squarely upon the shoulders of those whom it would serve as an auxiliary-the naval aviation organization and the naval service at large for which it provides extension of an already powerful striking arm. It must be developed and operated in exactly the same manner and by the same forces as the aircraft carrier. It is the responsibility of the Navy in general and of naval aviation in particular. The possibility exists of developing an auxiliary which can multiply many times the strength and sea-keeping qualities of our primary naval offensive weapon. We would be unwise to ignore it. In closing, we refer again to the writings of DuPlessis who attempted “to draw attention to questions too long neglected and to provoke their solutions rather than furnish them.”