CHAPTER III Aerial Warfare

GENERAL PRINCI PLES

Before we can draw up an accurate estimate of the scope of an Independent Air Force, we must first consider the following point: An Independent Air Force is an offensive force which can strike with terrific speed against enemy targets on land or sea in any direction, and can force its way through any aerial opposition from the enemy. From this fact emerges this first principle governing its operation: An Independent Air Force should always operate in mass.

This is the same principle which governs warfare on land and sea; and therefore the material and moral effects of aerial offensives — as of any other kind of offensive — are greatest when the offensives are concentrated in time and space. In addition, keeping together in mass in its operations makes it possible for the Air Force to force its way through aerial opposition successfully.

The radius of action of an Independent Air Force obviously must depend upon the radius of action of the planes comprising its units. But because all its units cannot be located at a single base, the disposition of the various units in relation to one another and to the general theater of war have some influence upon the radius of action. Once the disposition of its units has been decided, the Air Force’s field of mass operation against enemy targets can be shown on a military map simply by tracing the periphery which can be reached by all units. It is self-evident that any enemy target, on land or sea, within this line can be reached with equal facility by the entire Air Force in a few hours, at most in the time needed to cover the maximum distance between its bases of operation and any given point on that periphery. The attack may therefore be prepared in complete secrecy and launched without fore warning the enemy, with the offensive retaining the advantages of operational initiative. And, considering the suddenness of the attack, it is unlikely that the enemy would have time enough to parry the blow effectively either in the air or from the ground. Whatever he might be able to do, in general he could oppose the attack with no more than a fraction of his air forces.

Whatever the total strength of an Independent Air Force, provided it has at its disposal an adequate number of bombing units, the attack can be successfully directed not only against a single target, but against a number of them within the same zone. Since a bombing unit is potentially able to destroy any target on a specified surface, a fully activated Air Force is potentially capable of demolishing as many such targets, or surfaces, as there are bombing units. An Air Force of 50 bombing units, each capable of destroying a surface 500 meters in diameter, could in a single flight completely destroy 50 enemy objectives, such as supply depots, industrial plants, warehouses, railroad centers, population centers, et cetera.

In considering the objectives situated within striking distance of the Air Force, it would be advisable to subdivide the area into zones of 50 targets each. If we get 10 zones when the subdivision is mapped out, it means that the Air Force has the potential capacity to destroy all enemy objectives in that area of land or sea in ten days of operation, after which its striking power can be transferred to other zones designated for destruction.

All this sounds very simple; but as a matter of fact the selection of objectives, the grouping of zones, and determining the order in which they are to be destroyed is the most difficult and delicate task in aerial warfare, constituting what may be defined as aerial strategy. Objectives vary considerably in war, and the choice of them depends chiefly upon the aim sought, whether the command of the air, paralyzing the enemy’s army and navy, or shattering the morale of civilians behind the lines. This choice may therefore be guided by a great many considerations— military, political, social, and psychological, depending upon the conditions of the moment.For example, I have always maintained that the essential purpose of an Air Force is to conquer the command of the air by first wiping out the enemy’s air forces. This, then, would seem to be always the first objective of an Independent Air Force. But this is not always the case. Take,for instance, a case when the enemy’s aerial forces are so weak it would be a waste of time to devote men and materials to so unimportant an objective. It may be more profitable to subject the enemy to various other offensive actions instead, thereby doing him far more damage. Let us suppose — hypothetically, of course — that Germany had an Air Force of the strength described above, and decided to attack France, who was armed only with the aerial means now at her disposal. How long do you think it would take Germany to knock out not only the French flying forces, but the very heart of France?

The same thing is true of the grouping of enemy objectives into zones and in the disposition of the zones themselves, dependent as they are on diverse factors of vital consequence to the conduct of aerial operations as a whole. On this aspect of aerial warfare I do not believe it possible to lay down any specific rules. It will be enough to keep in mind the following basic principle, which is the same one which governs warfare on land and sea: Inflict the greatest damage in the shortest possible time.

In the light of this principle the value of the surprise attack is obvious. A really strong Independent Air Force such as the one described above could inflict upon an unprepared enemy such grave damage as to bring about a complete collapse of his forces in a very few days. To confirm the truth of this statement, I suggest that the reader solve for himself the following military problems:

Given a possible enemy armed with an Independent Air Force of enough bombing units, each capable of demolishing a surface 500 meters in diameter, and with an adequate radius of action —

1. How many bombing units would be needed to cut all rail communications between Piedmont and Liguria, and the rest of Italy, in a single day?

2. How many bombing units would be needed to cut Rome off from all rail, telegraph,telephone, and radio communication, and to plunge the city itself into terror and confusion by the destruction of governing bodies, banks, and other public services in a single day?

If the reader remembers that by a 500-meter surface we mean an area of that dimension upon which a variety of explosive, incendiary, and poison-gas bombs will be dropped, he needs must answer the questions with very small numbers indeed; and his conception of the power of this new weapon of warfare will be that much clearer and nearer the truth.

THE DEFENSE

The very magnitude of possible aerial offensives cries for an answer to the question,“How can we defend ourselves against them?” To this I have always answered,“By attacking.”

More than once I have stressed the preeminently offensive character of the air arm. Like a cavalry corps (unless it is dismounted), whose best defense is always to attack, the air arm depends upon attack for its own best defense, to an even greater degree, in fact. But before we go on with the air arm, we should thoroughly understand what we mean by the term“to attack.”

Let us suppose that Nation A is armed only with combat units and depends upon them in case of war to repel the attack of Nation B’s Independent Air Force. What do you think would be their respective situations at the outbreak of hostilities? The probability is that the air force of Nation A would have to seek for B’s Independent Air Force, find it, compel it to fight, and defeat it.

To find it is the crux of the matter. One may look — but where? The air is a uniform element everywhere; there are no signposts to show the road Independent Air Force B will follow in attacking Nation A. The word“seek” becomes an abstraction; and“to find” is a possibility, not a probability. For A’s air force to compel B’s Independent Air Force to engage in battle, A must have greater speed than B; to win, A must be stronger than B and have good luck besides.But while air force A’s search for Independent Air Force B is going on unsuccessfully, B can strike at A’s territory and do enormous damage, with A helpless to inflict any damage at all on Nation B. If, however, Nation B considers A’s air force dangerous, her Independent Air Force will doubtless concentrate her attacks upon demolishing everything essential to the functioning of A’s air force. A’s wasted time looking for Independent Air Force B will then result not only in a futile joyride, but in a real if indirect defeat, since her air potential will have been wasted without her having had a chance to engage Independent Air Force B in combat.

If we also consider that the air force of Nation A must operate in mass in order to be in the best position to win, the question comes up of where and when to concentrate those forces,operating as they are from scattered airfields.

This kind of action is essentially defensive in spite of its offensive appearance, and it has all the disadvantages of the defensive. To attack on land means to attack, without the need of scouting for them, fixed targets immovable upon the surface, targets which are the very lifeblood of an opponent’s air force. On the sea, conditions are different. Naval bases are as a rule so strongly fortified that it is practically impossible for hostile naval forces to destroy them. This fact increases the importance of naval battles fought to prevent or carry out subsequent possible action against land targets by one belligerent or the other. Things would be radically different,however, if naval bases could no longer be protected, and instead were subject to destruction in a few hours by naval forces. In such a case the destruction of naval bases would set the value of battle fleets at naught, because it would prove of incalculable help in crippling the operating efficiency of such fleets without wasting time and materiel trying to catch and sink them on the open seas.

For a nation to be equipped with an air force intended for aerial combat alone is not only to jeopardize the home front, but also to preclude any possibility of offensive action against enemy objectives — a condition of profound aerial inferiority.

The only really effective aerial defense cannot but be indirect; for it consists in reducing the offensive potentiality of the opponent’s air forces by destroying the source of aerial power at its point of origin. The surest and most effective way of achieving this end is to destroy the enemy air force at its bases, which are found on the surface. This is the principle which governs the situation: it is easier and more effective to destroy the enemy’s aerial power by destroying his nests and eggs on the ground than to hunt his flying birds in the air. And every time we ignore this principle we commit an error. Therefore, even if a nation has no other end in view than self-defense, it should be armed with an Independent Air Force capable of launching powerful offensives on land and sea.

It remains for us to take up the question of what I shall call local defense, meaning defense of singularly important points on one’s land and sea territory. Theoretically there are two ways of making this defense effective: by preventing enemy bombardment of them and by immediate repair of the damage inflicted by bombardment. This last appears at once impossible to effect,since it would be impossible to bomb-shelter entire cities with their rail centers, port facilities,supply bases, factories, and so on. In a measure aerial enemies could be kept at a distance and prevented from bombing certain objectives either by antiaircraft fire or by defensive aerial operations. Since antiaircraft guns are limited in range and not effective enough, practically speaking, to be of any great value, large numbers of them would have to be used; and since any country has a great many vital centers to be defended, even partial protection of them would require an enormous number of antiaircraft guns.

Moreover, the fact must be taken into consideration that antiaircraft guns may be neutralized by the escorting combat units’ drawing on themselves the fire of the guns. These operations are even safer at a low altitude than at a higher one, for the simple reason that the angular variation of the gunfire would have to be greater to keep the diving planes in sight. A plane flying at 100 meters is far more difficult to hit than one flying at 2,000 meters because the angular variation is about twenty times greater. If, therefore, the escorting combat planes should dive with machine guns wide open straight at the gun emplacements, it would be very unlikely that the gunners could stay at their posts and keep firing at the high-flying bombing units. In all probability, if they were not quite forced to drop the guns and take up the rifle, they would naturally shift their fire, trying to hit the immediate menace, hard as it might be to keep them in sight. For my part,I maintain — and war experience has already confirmed me in my opinion — that the use of antiaircraft guns is a mere waste of energy and resources.

As for the utilization of aerial units for purely defensive purposes, we have only to recall that if an enemy’s Independent Air Force operates efficiently, as presumably it will, it will function in mass, so the defensive units must at least be equal to the combat units of the hostile Independent Air Force. To defend effectively all areas threatened by such an Air Force would require a defensive force equal to the total combat strength of the attacking Air Force,multiplied by as many times as there are defensive positions to be protected. To obtain even this negative result it would be necessary to spend an enormously greater amount of resources than the enemy had to spend to obtain a positive result. This clearly demonstrates that it is both cheaper and wiser to put these resources to work where they will do the most good, for offensive purposes.

In conclusion, no local defense can be very effective when confronted by an aerial offensive of this magnitude; therefore, the expenditure of men and resources for such a purpose goes against the principles of sound war economy.

Viewed in its true light, aerial warfare admits of no defense, only offense. We must therefore resign ourselves to the offensives the enemy inflicts upon us, while striving to put all our resources to work to inflict even heavier ones upon him. This is the basic principle which must govern the development of aerial warfare.

THE DEVELOPMENT OF AERIAL WARFARE

As long as aerial forces remain mere auxiliaries of the army and navy, there will be no real aerial warfare in case of conflict. True, there will be air battles of major and minor proportions,but always subject to land or sea operations. Before any real aerial warfare can take place, its basic elements, such as planes, personnel, and their organization into an autonomous fighting body, must first be created and forged into an efficient fighting organization.

Under the circumstances, the first nation to arm herself with a real Independent Air Force will be in a superior military position, at least until other nations follow her example; for she will be in possession of an offensive weapon of formidable power, while the others will be dependent upon mere aerial auxiliaries. No doubt the necessity of establishing military equilibrium among the nations will induce others to follow her lead.

To study the development of aerial warfare, let us consider two cases: (1) a war between Nation A, armed with an Independent Air Force, and Nation B, without one; and (2) a war between two nations, both armed with an Independent Air Force.

An Independent Air Force must be always ready for action; otherwise 90 per cent of its effectiveness is lost. Given the speed of its units, no matter how widely dispersed their bases of operation may be in time of peace, it should be able to concentrate its forces along its line of battle and be ready for action in a few hours. If civil aviation units, scattered over the country,are a part of the Air Force’s organization, they must be located where their integration into the Air Force can be accomplished as quickly as possible. In short, the Independent Air Force must be organically and logistically organized so that it can go into action immediately upon the outbreak of hostilities.

Now let us examine the first case. Independent Air Force A begins its action to catch Nation B in the midst of mobilization. But let us assume that Nation B is found to have immediately mobilized all her military aviation. Only her pursuit and bombing specialties, however, could take part in the battle, because her other specialties are suitable only for integrating the action of her naval and land forces. It is clear, then, that Independent Air Force A will have freedom of action, for B’s pursuit aviation certainly could not hinder it. On the contrary, assuming that Air Force A has an adequate number of combat units, it will be able to inflict losses on B’s pursuit aviation. Thus Air Force A will rapidly gain command of the air by destroying the mobilization,maintenance, and production centers of Nation B’s aviation.

Once the command of the air has been won, the combat units of A’s Independent Air Force will naturally cease functioning solely to protect bombing units and will be used to neutralize the fire of antiaircraft batteries during bombing operations by the entire Air Force, and to bomb and machine-gun troop concentrations, supply trains, transport or marching columns, et cetera.Furthermore, if constructed to undergo the necessary conversion in equipment, these combat units can quickly be transformed into first-rate bombing planes. Therefore, with the command of the air an accomplished fact, Independent Air Force A will have won complete liberty of action to strike at will, with no risk to itself, over all the enemy’s territory, and quickly bring him to his knees.

By bombing railroad junctions and depots, population centers at road junctions, military depots, and other vital objectives, Air Force A could handicap the mobilization of B’s army. By bombing naval bases, arsenals, oil stores, battleships at anchor, and mercantile ports, it could prevent the efficient operation of B’s navy. By bombing the most vital civilian centers it could spread terror through the nation and quickly break down B’s material and moral resistance.

The reader who thinks this picture overdrawn has only to look at a map of Italy, and imagine himself the commander of an Independent Air Force belonging to any of the nations on our frontiers. Let him remember that his Air Force is capable of destroying 50 surfaces 500 meters in diameter every day; and then ask himself how many days of operation it would take to achieve the aim described above. He must also take into consideration the fact that, even in the present stage of aeronautical development, the daily operational strength of such an Independent Air Force would be, even if only half of it were used on alternate days, about a thousand machines, requiring only a few thousand men to man it. Then he may draw his own conclusions.

At this point I want to stress one aspect of the problem — namely, that the effect of such aerial offensives upon morale may well have more influence upon the conduct of the war than their material effects. For example, take the center of a large city and imagine what would happen among the civilian population during a single attack by a single bombing unit. For my part, I have no doubt that its impact upon the people would be terrible. Here is what would be likely to happen to the center of the city within a radius of about 250 meters: Within a few minutes some 20 tons of high-explosive, incendiary, and gas bombs would rain down. First would come explosions, then fires, then deadly gases floating on the surface and preventing any approach to the stricken area. As the hours passed and night advanced, the fires would spread while the poison gas paralyzed all life. By the following day the life of the city would be suspended; and if it happened to be a junction on some important artery of communication traffic would be suspended.

What could happen to a single city in a single day could also happen to ten, twenty, fifty cities. And, since news travels fast, even without telegraph, telephone, or radio, what, I ask you, would be the effect upon civilians of other cities, not yet stricken but equally subject to bombing attacks? What civil or military authority could keep order, public services functioning,and production going under such a threat? And even if a semblance of order was maintained and some work done, would not the sight of a single enemy plane be enough to stampede the population into panic? In short, normal life would be impossible in this constant nightmare of imminent death and destruction. And if on the second day another ten, twenty, or fifty cities were bombed, who could keep all those lost, panic-stricken people from fleeing to the open countryside to escape this terror from the air?

A complete breakdown of the social structure cannot but take place in a country subjected to this kind of merciless pounding from the air. The time would soon come when, to put an end to horror and suffering, the people themselves, driven by the instinct of self-preservation, would rise up and demand an end to the war — this before their army and navy had time to mobilize at all! The reader who thinks I have over-colored the picture has only to recall the panic created at Brescia when, during funeral services for the victims of an earlier bombing — a negligible one compared with the one I have pictured here — one of the mourners mistook a bird for an enemy plane.

Now to the second case, of two nations each armed with an Independent Air Force. It is easy to see that in this case, even more than in the first one, the nation who struck first would have the edge on the enemy; or, conversely, how imperative it would be to parry as well as possible the enemy’s blow before it struck home. To simplify the situation, then, let us admit that both Independent Air Forces could begin operations simultaneously. We have already seen that the fundamental concept governing aerial warfare is to be resigned to the damage the enemy may inflict upon us, while utilizing every means at our disposal to inflict even heavier damage upon him. An Independent Air Force must therefore be completely free of any preoccupation with the actions of the enemy force. Its sole concern should be to do the enemy the greatest possible amount of surface damage in the shortest possible time, which depends upon the available air forces and the choice of enemy targets. Whatever resources, of men, money, and equipment,are diverted from the strength and essential purpose of an Independent Air Force will result in slowing down the conduct of the war and delaying its final outcome.

The choice of enemy targets, as I have already pointed out, is the most delicate operation of aerial warfare, especially when both sides are armed with Independent Air Forces. In such a case the final decision depends upon the disequilibrium between the damage suffered by the enemy and his powers of recuperating from a blow which must be struck as quickly as possible, lest the enemy strike at us first. Of course, it may still be possible for one side to use its Independent Air Force to conquer the command of the air, which would ultimately win the war. But there may not be time enough for this if the other side succeeds in striking first and throwing the country into complete confusion.

The truth of the matter is that no hard and fast rules can be laid down on this aspect of aerial warfare. It is impossible even to outline general standards, because the choice of enemy targets will depend upon a number of circumstances, material, moral, and psychological, the importance of which, though real, is not easily estimated. It is just here, in grasping these imponderables, in choosing enemy targets, that future commanders of Independent Air Forces will show their ability.

Once the choice of enemy objectives and the order of their destruction have been determined,the task of the Air Force becomes very simple — to get on with their destruction in the briefest possible time, with no other preoccupation. In the case we are considering, therefore, both Air Forces will, at least in theory, proceed simultaneously in mass from their points of concentration toward their chosen objectives, without seeking each other out on the way. Should they happen to meet in flight, an air battle is inevitable; but I repeat that their purpose is not to seek each other out and fight in the air.

I consider this phase of aerial warfare very important, and I should like to pause here to clarify it further. Let us suppose that one of the Air Forces does seek out the other; but meanwhile the latter, avoiding an encounter, goes straight to its chosen objectives. He who seeks may find;but he may also return empty-handed. If one Independent Air Force deviates from its essential purpose, wastes time and fritters away its own freedom of action by seeking out the enemy in the air, the chances are not only that it will fail to find the enemy Air Force in the air, but also that the latter is at that very moment carrying out unchallenged its operations against the home territory. The one will have accomplished its task successfully; the other will have missed its opportunity and failed. In this kind of war, in which time is a vital factor, such a failure may have grave consequences in the outcome of the war, and should at all costs be avoided.

Speaking of aerial actions, I have already mentioned the possibility of having units of an Independent Air Force operate on alternate days; but I meant it merely as an illustration of how an Air Force might achieve results of major importance even with only half her strength,or with a relatively small number of planes. But during actual operations it would be an error to employ the strength of the Air Force piecemeal; for the purpose of an Independent Air Force is to inflict upon the enemy the greatest possible damage in the shortest possible time. The potential strength of an Independent Air Force should always be used to its fullest, with no thought of economy, especially when confronted by another equally strong Air Force which could do equally heavy damage. To replace personnel and equipment with fresh reserves may be expedient; but the Air Force itself — that is, its full complement of planes — should always remain in the air battering at enemy targets. It is the total effect of these bombing operations which decides the outcome of the conflict in favor of that Air Force which succeeds in dumping the largest quantity of bombs in the shortest time.

In presenting these ideas of the general character of aerial warfare, I have attempted only to show that if aerial warfare in its broad outline looks like a simple matter, it nevertheless presents staggering problems, the solution of which is very complex. But even in this brief resume we can catch a glimpse of the heights of atrocity to which aerial warfare may reach.

When we stop to think of the magnitude and power of aerial offensives, and realize that no really effective method of parrying them exists; and since it would be futile to divert aerial forces to defense, the phrase“to submit to whatever damage the enemy may inflict” becomes a phrase expressing actual circumstances of tragedy attending aerial warfare.

Tragic, too, to think that the decision in this kind of war must depend upon smashing the material and moral resources of a people caught up in a frightful cataclysm which haunts them everywhere without cease until the final collapse of all social organization. Mercifully, the decision will be quick in this kind of war, since the decisive blows will be directed at civilians,that element of the countries at war least able to sustain them. These future wars may yet prove to be more humane than wars in the past in spite of all, because they may in the long run shed less blood. But there is no doubt that nations who find themselves unprepared to sustain them will be lost.

THE FUTURE

The matters I have been discussing up to this point are all actual possibilities which could easily be put into practice with the means existing at the moment. By that I mean that any nation, if convinced of its value and expediency, could make practical application of present day aerial weapons to the science of making war along the lines I have described.

Having accepted this premise, we can now look toward the future — a near future, be it understood, and no idle exercise of the imagination, but a future which takes into account prevailing tendencies in the technical development of aviation; tendencies which point out the road we must follow if we wish to keep abreast of technical advances for tomorrow’s use.

The technico-practical problem faced by aviation is to make aerial navigation safer, more dependable, more economical, and in general better suited to the needs of society. Study of the problem is therefore directed toward realizing these four aims:

1. To increase the safety of flying and of take-off and landing facilities.

2. To exclude materials which warp and deteriorate in use today in the construction of airplanes.

3. To increase the carrying capacity and radius of action of airplanes.

4. To increase the speed and give better performance on less fuel.

Improvement along these lines will give the airplane much greater utility in peacetime and in wartime as well.

I shall now briefly analyze these trends.

1. To increase the safety of flying and of take-off and landing facilities: While in the air an airplane is self-stabilizing and tends automatically to maintain equilibrium. If an airplane has enough space beneath it, and if the pilot does not willfully keep it off balance against its natural tendency to right itself, whatever positions the plane may go through, eventually it will end up in its natural flying position. This phenomenon is the basis of aerial acrobatics — nose dives,spirals, spins, loops, and so on. To execute any of these acrobatic stunts, the pilot has only to throw the plane off balance in a certain way; to straighten out, he has only to stop interfering,and the plane will automatically regain its equilibrium. The equilibrium of a plane may also be disturbed by abnormal air conditions — air pockets, storms, cross-currents, et cetera; but in this case too, once the disturbing action of the air has ceased, the plane will automatically regain equilibrium. In short, a plane may lose its natural equilibrium in the air for a number of reasons owing to abnormal air conditions or to actions of the pilot.

These disturbing air conditions usually prevail at low altitude, near the surface of the earth where atmospheric pressure is greatest. Just as sea waves are more irregular near the shoreline,air currents, even if generated by entirely different influences, are more pronounced near the surface, which is in effect the shoreline of the air.

As I explained above, a pilot may willfully throw his plane off balance, in which case the assumption is that he has it under control and can regain equilibrium; or he may make an error in maneuvering and lose control of the plane. Losing control may, of course, happen at any altitude. If the pilot keeps his head he may easily straighten the plane out in time, if he has enough space beneath him. But if he loses his head and the plane continues out of control, he may crash no matter what the altitude.

All in all, we can see that the higher the altitude, the safer flying is. But if some mechanical device could be built into the plane to prevent the pilot from throwing it off balance whether from voluntary or involuntary action, more than half of the accidents in flying would be prevented. Hence the tendency toward the invention of a mechanism — which we need not go into here — to keep the plane automatically self-stabilizing while in flight. An automatically equilibrated plane should be as simple to fly as an automobile to run. That is, an accelerator to increase the power of the motor in climbing or diminish it in descending, and a steering wheel to turn right and left. We shall certainly soon reach this goal.

As early as 1913, in the arsenal at Vizzola, a plane was constructed which took off, flew, and landed, simply with an accelerator and a steering wheel. This plane, which would not allow the pilot to lose equilibrium and reacted automatically to disturbing atmospheric conditions,hung up a world endurance record for automatic flights (over an hour). We can easily imagine the practical results of such an improvement, once it is firmly established.

Take-off and landing are two of the most difficult operations in flying, just as entering and leaving port are two of the most difficult operations in navigation. The reason for this lies either in the difference in the physical resistance of a plane passing from a fluid to a solid medium, or in air disturbances near the surface. Of the two, landing is the more difficult; and, as the shock upon touching ground is proportionate to the speed of the plane, the greater the landing speed,the greater the hazard.

Safety in flying therefore requires that a plane be able to land at a very low speed; while on the other hand more and more flying speed is demanded. Three hundred kilometers an hour have already been surpassed, and 300 kilometers an hour are equivalent to about 83 meters per second, or a little more than a quarter of the velocity of sound. Aeronautical science is therefore trying to develop planes of greater speed in flight and slower, safer landing and take off speeds. Surface improvements in the form of better airfields, runways, and signal systems will no doubt contribute to safety in aviation.

2. To exclude materials which warp and deteriorate in use today in the construction of airplanes: As a machine the airplane has marvelous accomplishments to its credit; but it is still a long way from what could be considered a hundred-per-cent perfect machine. Except in a few recent rare experiments, such perishable materials as wood and canvas are still used in the construction of planes. It is true that wood and canvas have certain characteristics of elasticity and lightness that we have not been able to duplicate even today in metals. On the other hand, their lack of structural homogeneity and their rapid deterioration from a number of causes, such as meteorological conditions, create a doubt of their permanent value. The ideal machine should be entirely of metal, because the characteristics of metal are definite and not easily altered. Hence the trend to construct airplanes entirely of metal, which, besides affording greater stability in construction, will minimize if not eliminate the necessity of housing planes in hangars. From this, especially in wartime, a great saving in time and labor can be effected.

3. To increase the carrying capacity and radius of action of airplanes: The trend toward increasing the carrying capacity of airplanes is in line with principles of sound economy and with the desire to increase the radius of action of the planes. Greater carrying capacity in a plane proportionately decreases total costs of construction and operation. A two-passenger plane carrying two passengers instead of one has no need to double its personnel because of the extra passenger. It costs less to transport ten passengers, or ten quintals of cargo, with a single plane than with ten planes. Moreover, by varying within certain limits the proportion between useful load and fuel weight, an increase of total carrying capacity of planes would also extend their radius of action. And no regular transoceanic service could be effectuated except with planes of greater carrying capacity than those in use today.

A plane is kept aloft by its wings, the stress of its total weight being distributed over its wing surface. But since the weight per square meter of its wing surface cannot be increased beyond a certain predetermined limit, its carrying capacity will depend upon its wing surface.Therefore, the greater the carrying capacity desired, the greater will have to be the wing surface.At one time triplanes seemed to offer the best possibility for maximum wing surface, but even this maximum could not be forced beyond certain limits. Recently, however, a new type of plane made its appearance in Italy — a tailless plane based on a series of triplane cellules and operated by a new system of controls. It was tested in the air, and the experiment proved practical.

Since planes of such weight probably could not land or take off except on liquid surfaces,we may have to build artificial lakes for their landing. That would be of some military advantage, because in case of war enemy bombardment could not put liquid fields out of service as easily as ground fields.

4. To increase the speed and give better performance on less fuel: The increased speed of planes is mainly due to increased power of their motors. It follows that the greater the power of the motor, the greater its power to conquer air resistance, and the greater the resulting speed.But we can see that such a system cannot possibly be economical. The need is to increase the speed not by increasing motor power, but by diminishing air resistance. But that is not in our power. Air resistance is what it is. But it is a fact that air resistance grows less as a plane gains altitude. Therefore, the higher we go, if we could continue to develop the same horsepower, the greater would be the speed and the economy in performance.

But the matter is not so simple as it would seem at first sight, and the difficulty lies in keeping motor power. One of the factors in determining the power of a motor is the intake volume of its cylinders; that is, the amount of air and gasoline mixture used by a cylinder at each intake stroke. If the cubic displacement of a cylinder is one liter, it means that with each explosion in the cylinder a liter of carbureted mixture is used up.

The density of air varies with the level under consideration. If this density is 1 at sea level, at 5,000 meters it would be about 1/2 and at 18,000 meters it would be about 1/4. That means that at 5,000 meters a motor, while keeping unaltered the volume of its cylinders, would absorb only half the quantity (weight) of the carbureted mixture it would absorb at sea level; and at 18,000 meters it would absorb only one-tenth as much. Therefore, if the power of the motor is 1 at sea level, it decreases as it climbs, to 1/2 at 5,000 meters and to 1/10 at 18,000 meters.

This phenomenon is actually more complex than that, but what I have said here should be enough to show how, owing to rarefaction of the air, the power of a motor decreases as the altitude increases. This explains why every type of airplane has, as we say, a“ceiling,” a limit to the altitude it can reach. At that altitude the power of a plane’s motor is almost exhausted, and it cannot climb beyond that.

Theoretically, to develop the same power at various levels, a motor would have to absorb at any altitude air of the same density as at sea level. To obtain such a result, still theoretically, it would be enough to compress the air intake of the motor to the density of 1, the density of sea level, as the air becomes gradually lighter on climbing. Studies to find a practical solution to this problem are being conducted by technicians all over the world; and there is nothing to keep us from thinking that some day or other it will be solved for all practical, if not for theoretical,purposes.

But, since air resistance is proportionate to its density, if the resistance is 1 at sea level, it becomes roughly 1/2 at 5,000 meters and 1/10 at 18,000 meters. Therefore, if we could succeed in keeping the same motor power irrespective of altitude, an airplane capable of 150 kilometers per hour at sea level could theoretically do 300 kilometers an hour at 5,000 meters and 1,500 kilometers at 18,000; and there would no longer be any limit to its ceiling, for the higher it climbed, the more easily it could climb.

Naturally, these are all theoretical goals which practice will never be able to reach, but toward which aeronautical progress is tending; and in fact technicians do not despair of making it possible in the near future to travel regularly and economically at the 10,000-meter level,and at 500 kilometers an hour. When flying at such an altitude becomes the normal thing,passenger cabins should of course be hermetically sealed with constant air pressure at sea level density, as in the case of the motors. This possibility of heavy air traffic at great speed and economy will permit the extension of the plane’s radius of action and greater comfort aboard.

From what we can see of present tendencies in technical developments, we can be assured that aerial navigation will make a great spurt of progress, especially in long-distance travel.The day will come when no one will think of crossing the ocean by steamer, just as no one today thinks of doing it by sailboat. And since the offensive power of planes, considered as war machines, will be constantly increasing, there is nothing to prevent us from thinking that in the not too distant future Japan may be able to attack the United States of America by air, or vice versa.

I have dwelt upon the future only to emphasize the necessities of the present; and to the present I shall immediately return.