From time to time during the past decade the value and essential character of certain types of naval vessels have been seriously challenged before the court of public opinion. The force of certain of these arraignments has been admitted by the naval service and naval policy modified in those respects. To some, service opinion has been antagonistic and the proposed changes defeated. Certain others of these challenges have encountered intermittent opposition and indifference and remain unsettled to a large percentage of the general public.
Every naval officer is aware that the essential controversy has centered upon the relative potentialities and values of aircraft and surface vessels or, more specifically, battleships. The average officer believes that the question has been definitely decided by the existing naval policy calling for building and maintaining a balanced fleet with the fullest development of all types permitted by the dictates national policy and within the limitations of naval appropriations. This policy, thoroughly understood as it is by the service, has not received widespread publicity because it lacked those spectacular qualities that at times appear to be the sole criteria of news values. Consequently, a surprisingly large percentage of the general public believes that the Navy has failed to utilize aircraft to the best advantage and has, because of ultraconservatism and the stultifying effects of time-honored naval tradition, persistently clung to obsolescent types of surface craft the detriment of the national defense. Very recently a generally well-informed civilian, considerably above the average in intelligence, asked a naval aviator of his acquaintance the following question: “Don’t you fellows encounter a good deal of opposition and jealousy from the regular line officers?” His polite incredulity upon being answered emphatically in the negative is indicative of a somewhat popular misconception. For these reasons the writer believes that a general review of the question may be of value at this time.
Naval craft of all types, whether aerial, surface, or submarine, are essentially and primarily the means of transportation for placing a weapon or a trained observer in a chosen and advantageous position. As the process of observation is auxiliary to the employment of the weapon, the real problem, stripped of its nonessentials, is not the choice of a means of transportation for the weapon but rather a selection of the most suitable type of weapon. The true nature of the controversy under discussion is then resolved into a choice between the aircraft bomb and the large-caliber naval gun instead of one between the airplane and the battleship, provided, of course, that one believes a selection must be made between the two—a selection requiring an amendment in the existing naval policy and a definite commitment in favor of one type to the practical abandonment of the other. If such a choice is, for the sake of argument, deemed necessary then that selection must be made upon the basis of the relative values of the two weapons involved. The means of transportation for the selected weapon, being concomitant and connoted, will naturally follow.
In making such a choice certain comparisons are to be considered, such as effectiveness of hits from projectiles of the two types; rapidity of fire; accuracy and volume of fire; availability for use under varying conditions of time, locality, distance, and weather; and vulnerability to hostile activities.
In considering the relative effectiveness of hits, we are faced with a somewhat general popular misconception regarding the size of aerial bombs that may, considering the present stage of aerial development, be deemed practicable for use in naval warfare. Having been regaled with descriptions of the havoc that would be wrought by a 4,000-pound bomb and having viewed with great interest genuine photographs of actual bombs of this enormous size, the public has overlooked the fact that there are certain practical difficulties tending to preclude their use in naval warfare. These deterrents arise chiefly from the fact that aircraft are definitely limited as to the weight that can be carried aloft. Any increase in the military load must be achieved at the expense of the amount of fuel the plane is capable of carrying. A shore-based plane to be of real value against hostile surface craft must be capable of operating at least 500 miles from the coast. Considering the cruising speed of such a plane to be 125 miles an hour and that 2 hours of operation at the maximum distance from the base would be sufficient, it is apparent that the plane would require fuel for about 10 hours of flying. To carry a 4,000-pound bomb the plane would have to possess the ability to lift a weight, in fuel and armament alone, of something in excess of 10 tons. This, of course, would connote a plane of truly enormous size. While the design and construction of such a plane is possible, even if implying a higher degree of aeronautical development than obtains today, the size and lack of maneuverability inherent in such a design would subject it to a maximum of hostile aircraft attacks even though its own defensive armament could be made quite formidable. In addition, the inevitable drawbacks of such a design would be relatively slow speed and a moderate ceiling. These two factors would cause the plane to be exposed to antiaircraft fire from surface vessels for a longer period of time than would be the case when smaller and faster planes are considered. Likewise it would afford such an excellent target for such defensive gunfire that it is very doubtful, barring surprise or exceptionally favorable weather conditions, if it could reach the requisite dropping point over an alert enemy battle line. Therefore, until aircraft design reaches a considerably higher stage of development than obtains at the present time, it appears logical to conclude that the 4,000-pound bomb is impracticable for use against surface vessels with shore- based planes, even at moderate distances from the coast and for long-range operations it is an obvious impossibility. It might be argued that a plane to carry a bomb of this great size might be based on shipboard and, because of the relative proximity of its base to the actual scene of operations, be able to accomplish its mission without the necessity for transporting such a tremendous load of fuel, which, in turn, would permit of a smaller and faster design. Such an argument, however, would be advanced seriously only by those who do not realize such a plane would involve a total weight far greater than any ever lifted from the deck of a carrier and enormously in excess of any ever launched by catapulting.
It must not be construed that the writer is attempting any decrial of the potentialities of aviation or believes that the future of aeronautical development holds anything other than the most brilliant prospects. These arguments have been advanced merely to support his contention that this case is one of the numerous instances where the general public has been misguided by the extravagant claims of super-enthusiasts with the result that the progress of aviation has suffered more from this cause than from it’s own limitations.
If, then, it appears reasonable to exclude the 2-ton bomb from serious consideration, no such summary dismissal is defensible in the case of one half that size. It is true that no plane of intermediate speed and moderate size actually exists that is capable of carrying a 2,000-pound bomb great distances from its base. However, designs are in existence that could function while carrying this load at a distance of 500 miles from the base. At the present time these types are not designed for shipboard use, although the writer is of the opinion that the present stage of development in aeronautical engineering is sufficient to produce a plane of the required specifications in these respects. However, a shipboard plane of this type would involve a design of relatively great wing span. This would operate to reduce the number of planes that could be borne on the deck of any given carrier, not only because of the actual space occupied but also because of the increased difficulty in moving planes of such a size about on the flight deck. In fact, it appears quite reasonable to presume that the total weight of bombs capable of being dropped by all of the planes of a single carrier would be greater if the smaller plane should be used even though such a choice would involve a reduction in the weight of the individual bomb that could be carried by each plane to, for example, 1,000 pounds.
We have, then, as a basis for comparison of hitting effectiveness of the two weapons, the 16-inch-gun projectile on one hand and the 1-ton or 0.5-ton bomb on the other, the bomb weights depending upon the basing of the plane carrying the weight. Roughly speaking, the gun projectile of that caliber weighs as much as the larger of the two bombs. Obviously there exists a considerable latitude of choice with respect to the ballistic disposal of relative weights of case and explosive charge in either projectile. The limits to this choice in both instances are approximately equal so that, practically speaking, any given design of bomb may be duplicated ballistically in a gun projectile and vice versa. In practice, however, aircraft bombs which strike the target with less velocity than do big gun projectiles are designed to compensate for lack of penetration by increased disruptive force; in other words, they have a higher percentage of disposable weight assigned to the explosive carried.
This lesser striking velocity of the bomb results from the fact that any freely falling object in an atmosphere increases its speed of fall under the influence of the acceleration of gravity and against the air resistance. As the aerodynamical resistance increases at a higher mathematical rate than does the increase in velocity, a balance is eventually reached beyond which point no further increase in the velocity of the falling object is possible no matter how long the fall may continue. This maximum velocity, which varies with the shape of the object in question, is called its terminal velocity. That of the human body falling freely in air is approximately 112 miles an hour while that of the best streamlined aerial bomb is about 1,200 foot-seconds. However, to achieve this terminal velocity the bomb must be dropped from a relatively great altitude. The striking velocity of the gun projectile, on the other hand, is relatively unaffected by gravity and is more of a function of muzzle velocity and air resistance. Obviously at extreme ranges the difference between the muzzle and striking velocities of the gun projectile is at a maximum as in that case the retarding effect of the air has been operative for a longer period of time. Even so, the striking velocity of gun projectiles is greater than the terminal velocities of aircraft bombs, the disparity in favor of the shell increasing with a decrease in the relative range, not only because of increase in the striking velocity of the gun projectile at such ranges but also from the decreased speed of the bomb that is dropped from an altitude less than that requisite to the attainment of its terminal velocity.
Therefore, in weighing the relative effectiveness of bomb and big-gun hits, we have a theoretical equality in disruptive force and an actual penetrative advantage for the gun projectile. The mere fact that armor-piercing shells for use in naval guns actually carry a smaller weight of explosive than do aircraft bombs of equal weight cannot be advanced as an argument in favor of the relative effectiveness of the bomb hit, as the choice is a deliberate one and can be modified easily to parallel any possible ballistic arrangement in the bomb that could be proved to have definite points of superiority. Even if the 4,000- pound bomb later proves a practicability for use in naval warfare, it must be remembered that the projectile from a 20- inch naval gun would equal it in weight. While no 20-inch gun actually exists this is due to the present limitation upon the size of naval guns by international agreement rather than to any insuperable difficulties in the construction or service of such a weapon. When the 2-ton bomb definitely enters the picture there is no real reason to presume that future arms limitation agreement may not result in a similar arbitrary restriction on the size of aircraft bombs or in an increase in the maximum permissible caliber of naval guns. Hence the bomb hit merely equals the gun hit in disruptive force and has somewhat less penetrative effect at extreme ranges, while at intermediate distances the disparity in favor of the gun projectile is greatly increased. In fact, those who argue that the bomb hit is more effective than that of a big-gun are in reality and in the final analysis arguing not the case of the plane versus the battleship with the broad strategical and logistical implications involved, but rather the older and more limited ballistic controversy between the advocates of the high-explosive projectile and those who prefer one of armor-piercing quality.
When the accuracy of bomb dropping and gunfire is compared, the question of range is a primary one. In the case of the big gun, the battle range may be considered as being between 15,000 and 25,000 yards, as only exceptional circumstances would justify or require engagement at ranges outside of those limits in either direction. The normal dropping altitude for bombs depends upon the method used in aiming the missile. If a bomb sight is used to determine the proper dropping from an appreciable altitude over the target, surface gunfire will probably force the plane to approach at an altitude of at least 10,000 feet. Aerodynamic considerations would probably preclude the possibility of a heavily laden plane making the necessary attack from an altitude greater than about 15,000 feet. If the bomb is to be dropped at the end of a dive in which the pointing of the plane at the target serves as the process of aiming, the point of release may be 1,000 feet or slightly less. Considering these ranges as the expected battle ranges and as normal, we may assume, in view of the recent development in the accuracy of bomb dropping, that the bomb has an equal, if not slightly better, chance of hitting than does the projectile fired at comparable ranges. The bomb launched at the end of a dive may be considered as having been dropped at point-blank range and should hit with great frequency. However, this method of bomb dropping, while of great accuracy, suffers from the limitation of the size of bomb that may be employed. Such a dive with the necessary recover subjects the plane to tremendous stresses and a bomb of 1,000 pounds is considered to be the heaviest that could be used at present. Naturally, if the range is reduced in either instance, an increase of accuracy in both gunfire and high-altitude bombing may be expected, but as such ranges could ensue only from abnormal conditions, the expected battle ranges from the fairest basis for comparison. In accuracy, then, we have an equality between gunfire and high-altitude bombing while dive bombing, although more accurate than either, suffers from the use of a smaller projectile.
In individual rapidity of fire, the advantage rests entirely with the big gun, which can fire every 30 seconds or less. The individual plane, for the purposes of any single naval engagement, must be considered as being a single-shot, nonreloadable device for the launching of a bomb. For shore-based planes operating at a distance from their base this is obvious, while for carrier-borne aircraft rearming would involve a return to the carrier, reloading, and refueling, a second take-off and climb for altitude, and finally a return to the scene of operations—a matter of hours.
But when we come to consider volume of fire from the standpoint of collective effort, the advantage accrues to the other side as an aerial striking force may, to use a current colloquialism, “shoot the works” long before the battle line has made any visible inroads in its ammunition supply. In this connection the number of planes available is the governing factor. With our present force of battleships, approximately 100 bombing planes (a conservative figure), each carrying a 2,000-pound bomb, would be required to deliver a weight of metal equal to a single broadside from the big guns of the battle line. If 200 planes were available, the aerial force could be accorded a superiority in volume of fire in the ratio of 2:1, and so on. The relative volume of fire between bombing and big-gun fire is therefore dependent upon the numerical strength of the aerial striking force. If we arbitrarily limit the ammunition supply of the battleship to the very moderate figure of 100 rounds per gun, a force of 10,000 bombing planes would be required to equal the total weight of projectiles that the battleship force could hurl. While such an aerial force, or perhaps one half that size, could overwhelm and destroy the battle line because of its tremendous superiority in volume of fire, its materialization is chimerical because of the obvious difficulties in basing and supply.
Next to be considered is the relative availability of the two weapons for use under varying conditions. Because of the multiplicity of factors involved, the scope of this paper permits of discussion only in the most general terms. The first of these factors is that of range of action. As previously stated, the present stage of aerial development limits the operations of heavily laden aircraft to approximately 500 miles from their base. The big-gun carrier, on the other hand, has a range of action about eight times as great. Battleships may maneuver for days near the expected scene of operations while the endurance of planes is limited by their fuel capacity and is measured in hours. The bomb, because of the vastly greater speed of its vehicle, may be brought into action sooner than can the big gun with respect to any locality that is within the range of its means of transportation. On the other hand, at least one-half hour must elapse between the command for the take-off of the bombing planes and the actual dropping of their projectiles, while the big gun can be expected to fire within ten minutes after the sounding of the call to general quarters. When weather conditions are to be considered, it is true that there are certain relatively rare occasions when the operations of the big gun would be hindered and those of the bomb carrier facilitated. Nevertheless, unfavorable weather conditions may be usually expected to affect aerial operations more adversely than those of surface craft. In summation, it should be obvious that while certain factors are more favorable to the use of the bomb, the big gun may be considered as being more universally available under varying conditions.
There remains for discussion the relative immunity of the means of transportation of these two weapons to hostile activities. In the case of the plane, its chief protection is a function of its speed and maneuverability, while that of the battleship is derived from its structural strength. The battleship has, as one of its primary attributes, the ability to continue in action after being struck; the plane would be brought down by almost any sort of a hit. Naturally the problem is to hit the plane. This difficulty arises rather from its inherent speed and maneuverability than from the increased complexity of surface gunfire due to the introduction of the third dimension. Hence, the obvious remedy is to use a plane that nullifies as far as practicable this great asset. Such planes, designated in the naval service as fighting planes, possess greater speed and maneuverability and are admirably adapted for attacking the larger and slower bombing planes. As a discussion of aerial combat is not pertinent to this paper, it will suffice to say that a certain percentage of losses may be expected in a bombing squadron as a result of hostile aircraft, following which the surviving planes must run the gauntlet of anti-aircraft fire before reaching the requisite point for the release of their bombs. Therefore, one is fully justified in stating that the bombing plane suffers in comparison with the battleship in ability to continue its activities in the face of hostile resistance.
It appears that a preponderance of factors operates in favor of the big gun and that, if an immediate choice must be made between the two weapons, it would be one to the prejudice of the aircraft bomb. However, such a definite commitment would prove a step backwards and shut the door to a line of development that offers almost limitless prospects in the future. Also, it is entirely conceivable that circumstances might arise in which an aerial striking force, even if of moderate strength, might prove a more effective bulwark to the safety of the nation at that time than all the battleships afloat. To deprive ourselves of such an arm would be the equivalent of trusting the safety of the nation to luck. Conversely, even the most prejudiced are forced to admit that conditions might obtain that, while nullifying completely the ordinarily great potentialities of the bomb carrier, would permit of the unhampered utilization of surface craft armed with big guns. Is, then, the safety of the nation of such slight importance that it need not be safeguarded by forces capable of meeting any situation that might arise? If the answer is “No,” then the existing naval policy requiring the building and maintenance of a balanced fleet with the fullest development of all arms—surface, submarine, and aerial—is both logical and sound.
To demonstrate the matter more clearly, it might be profitable to consider the logical results of depriving the fleet of either aerial bombs or big guns. By the elimination of an aerial striking force, we would be able to devote all of the capacity of our carriers to scouting and fighting planes and thus improve the scouting efficiency of the fleet as well as its ability to defend itself against hostile aircraft. However, by so doing we would relieve the enemy of the necessity for preparing against a serious aerial attack unless the prospective engagement was certain to take place within range of our shore-based planes. This would permit a potential enemy to increase his effectiveness against our surface craft while reserving for his own forces the threat of a serious aerial assault upon our fleet.
If, on the other hand, we should decide to deprive our fleet of its battleship force and of its big guns, we could not effect the necessary changes as easily and as simply. In the first place it would be necessary to seek for a modification of the existing arms limitation agreement to permit us to increase our carrier tonnage. In view of the known attitude of certain foreign powers this would not be granted without considerable concessions of an indeterminate nature. It would then be necessary to build the additional aircraft carriers and their planes while training a large additional number of naval aviators. During and until completion of the process of transition, the safety of the nation would require the maintenance of the battleship force in full commission. Hence, even if the change could be effected rapidly, a considerable expansion in naval personnel would be involved with the attendant extra expense. After the process was completed, the need for the extra personnel would disappear and we would be forced to undergo all the evils inherent to a reduction in personnel. Let us assume that the dangerous period of transition can be safely undergone. The fleet would then consist of a main body of aircraft carriers together with supplementary cruisers, destroyers, and submarines. The function of these auxiliaries would be the protection of the main body against enemy light forces and the securing of information for its guidance. Our fleet, because of the vulnerability of the carrier type, would have to avoid surface contact with the enemy. This would impose the necessity for constant maneuvering at high speed upon our fleet which, in view of the increased fuel consumption at such speed, would act to the detriment of the effective range of action. This implies an increase in the difficulty of defending our nearer possessions, such as Hawaii and the Panama Canal, and would render the defense of those more distant practically impossible with resultant far-reaching political implications. It is true that the carriers themselves might be large enough to carry the greater fuel supplies necessary, but the smaller units of the fleet would be greatly handicapped in the absence of high speed, large cargo capacity, fuel ships capable of refueling those units at sea. The lack of battleships would increase the over-all vulnerability of the fleet to hostile aerial attacks and particularly so with respect to what would then be its major units, the carriers. Most critics will admit that a 2,000-pound bomb will sink or put out of action any type of naval vessel other than battleships or battle cruisers. Hence, a single bomb hit on any unit of the fleet would rob us of its services. In addition, a potential enemy, knowing that he would not be opposed by heavily armored vessels, might profitably discard his armor-piercing projectiles in favor of one having smaller penetrative qualities but carrying a larger charge of explosive. Such big-gun projectiles would then rival the effectiveness of the aircraft bomb against a lightly armored vessel and we could expect the loss of a unit of our fleet every time the enemy scored a hit with any weapon. In summation, a fleet of this composition would have the following comparative disadvantages: greater vulnerability, particularly to a surprise attack; inability to defend our over-seas possessions as well as does the present fleet; the necessity for avoiding surface contact with the enemy; decreased range of action; and inability to operate its most effective weapon under as wide a range of weather conditions as would a more balanced fleet. Its relative advantages, higher speed, and a greater volume of fire can hardly be considered as fully commensurate.
The final conclusions that may be drawn are:
(1) That the big naval gun is at present the most effective naval weapon.
(2) That the aerial arm of the fleet is complementary rather than subordinate and thus essential.
(3) That the building and maintenance of a balanced fleet composed of all types is essential to the safety of the nation.