DESIGN
and
OPERATION
of United States
COMBAT
AIRCRAFT

Office of War Information

The Following Report on the Performance of American Military and Naval Aircraft was Prepared by the Office of War Information. Copies may be obtained, upon request, from the Division of Public Inquiries, Office of War Information. Washington, D. C. October 19, 1942

Design and Operation of
United States Combat Aircraft

THE people of the United States have a right to know, within those limits made necessary by military security, the strengths and weaknesses of their fighting men and fighting machines. It is their right to be informed and to debate these vital questions. But a degree of confusion has marked the public discussion of American combat aircraft. It has not been fully realized that the test of battle is the only valid one for an Army or Navy plane, whatever its type.

Failure of the public to appreciate this fact, and the additional one that there is no all-purpose plane, has bred doubt and discouragement. From believing their warplanes the best in the world, some people have swung to a conviction that British, German, and Japanese planes are superior. Then, their hopes brightened by accounts of American air victories, they have gone back to their original optimism.

The truth lies between the two extremes. The public, delving into a field of great complexity, has had to base its judgment on what it read and heard. Some of its information, whether praising or damning American military aircraft, was obviously inexpert. A good deal was either superficial or based on inadequate evidence. Part of the confusion arose from the difficulties inherent in translating a highly technical subject into terms comprehensible to the average intelligent -- but not technically trained -- American citizen.

A Report on Existing American Planes
This report is not a study of air strategy or an inquiry into the future of aerial warfare -- subjects to which the Office of War Information may at some future date return. The purpose of the report is to provide a background so that Americans can judge the capabilities and performances of United States combat aircraft

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Experts with varying degrees of ability have testified as accounts of victories and defeats in the air reached the United States. Generally speaking, the public could not form an adequate judgment because of over-simplification of one of the most complex subjects in all the complicated aspects of modern war: the designs and operation of military aircraft. Sometimes the experts were unfair because they demanded the impossible. They forgot the peace-minded past of their country. They ignored the patent fact that we as a nation had been unwilling to spend the money for aircraft development which should have been spent in preparations for the day when the Nation would be at war.

A Balanced Air Force the Goal
A balanced air force is the goal for which the United States and all the other warring powers. No campaigns in this specialized war have been won by tanks alone or by cavalry or by any other arm, friendly or enemy, are aiming and have been aiming. To compare this with a balanced ground army is exact. It is a military truism, with which the public now is abundantly familiar, that victory goes to the side with the best balance for a given situation, best employed.

Similarly, no war in the air will be won with an air force concentrated on the fighter, the bomber, or any other craft. The complete air force must be balanced. It needs fighters of various types capable of operating with maximum effectiveness through all the levels of air operation. It must have short-range fast-climbing interceptors for defense against enemy bombers, long-range heavily armed slugger types for the protection of its own bombers.

The complete air force needs bombers for best operations in all the specializations of that decisive activity; dive bombers for attacks on enemy surface craft, for cooperation with ground troops, and for other purposes; torpedo planes for attacks on enemy shipping and warcraft. It calls for long-range reconnaissance craft, for light and medium bombers capable of a variety of work, especially low-altitude strafing. It needs transports for its service operations, aircraft for the taking and developing of pictures of enemy targets, planes for coastal patrol and offshore operation against enemy shipping.

No nation ever has attained this development in its fullness -- although the United Nations in their combined air squadrons are close to it -- because no group of military men conceivably could

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anticipate all the demands to be made by war. In reaching toward the ideal, the United Stales air forces also have been hamstrung in the past by disagreement in their own fighting services as to the weight and power to be wielded by air power. In spite of this, the United Slates went into the war with a well integrated air force; not all of it distributed with maximum effect. The versatility of many of our types, notably our heavy bombers, made it possible to use one class of aircraft for a variety of purposes, for example, the employment of modified bombers as transports. Yet it is characteristic of a great deal of the criticism leveled against United States planes that no consideration was taken of the concept of the balanced air force. Probably the same thing would have been true of German and Japanese critics, if they had been free to speak their minds.

Within recent months there has been a new type of appraisal of fighting aircraft which projected the known performances of a warcraft (the Boeing B-17 Flying Fortress) into the future. The verdict of this school, in which many United Slates newspaper writers joined, was that the Flying Fortress was unfit for combat over the battlefields of Europe.

Bombers in Combat
The test of battle completely disproved this. Actual employment of the B-17 over Europe has exceeded even the fondest expectations of its American proponents. It has shown that the B-17 is capable of high-altitude day bombing of such precision that it astounded Allied observers. Combat has proved the great firepower of the Flying Fortress as well as its inherent toughness under enemy attack. This gave it decisive protection against enemy fighter attack, while its ability to operate at high altitudes cut down its vulnerability to antiaircraft fire.

The public already is familiar with some of the B-17's feats, such as the recent fight over Occupied Europe in which gunners in a flight of B-17's engaged 40 German fighters. Ten Focke-Wulfs were knocked down and eight more were claimed as "probables." All B-17's returned to their British bases, although one had been hit by six cannon shells and more than 200 machine-gun bullets.

In the October 10 raid over France -- the largest and most damaging daylight raid ever staged over Europe -- 115 Flying Fortresses and Liberators accompanied by Allied lighters proved their ability to fight their way through to a target and back again

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against the large and fierce opposition of the Nazis' newest and best Messerschmitts and Focke-Wulfs. We lost only four of our bombers while more than 100 enemy planes were destroyed or damaged.

In the B-17's test in the European theatre, there have been many other examples of the same kind of superlative performance. All of them follow the pattern of this plane's rugged, hard-hitting record in the Pacific. It is a tribute to the determination of the Army Air Forces in developing this type of craft that the same kind of record has been made by the Consolidated B-24 in Egypt and in other areas. Thus what applies to the B-17 applies in general to the work that the B-24 has done. In these airplanes the United States has weapons of marked and proven superiority in their fields. The example of the United States' heavy bombers is cited to illustrate a basic principle in the appraisal of any combat airplane: peacetime capabilities can strongly indicate its qualities, but only operations in the field can prove them. Even then the trial of battle can prove them only in the field in which the record is made. The fighter that performs capably in the Southwest Pacific can turn out to he completely unsuitable for the defense of Britain; the bomber that is best for heavy night attacks on German industry can well be capable of no more than a second-class performance in the Solomons. On the vast pegboard of war the holes to be plugged are of a great variety of shapes. Only the pegs cut to their measure can fill them.

Aerial War on Many Fronts
For the United Stales, the requirements of this war are more varied than they are for any other combatant. Today aircraft of the Army Air Forces, for example, are in daily operation against the enemy on many fronts with variations in climate and battle situations that are the severest possible test of military aircraft. In the Aleutians, they are operating over water, in cold and forbidding weather, against Japanese establishments and aircraft. In the Solomons, operations are in stifling heat and drenching rains. In the desert, heat is compounded by swirling sand. In Australia and New Guinea a given aircraft in a single day may fly from subtropical temperatures to the chill of early spring. Operations continue, in these areas and in Europe, India, China, the central Pacific. They go on in the Caribbean, off our own coasts, off the coast of South America. It is proof

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of the soundness of United Slates design and the versatility of American crews that they do go on, under conditions more varied and difficult than men and machines ever have had to meet before.

Some Planes Badly Designed
Some American warplanes are badly designed or ill-matched against the equipment of the enemy. Some planes now in action have definite deficiencies, even within the purposes for which they were designed, but even such aircraft often have fought admirably, because of their positive virtues and inherent soundness despite such tactical handicaps as climate, inadequate air-raid warnings, and other considerations of war. It also is a fact that some American aircraft have proved excellent in every theatre in which they have been employed.

It is a truism that no military aircraft are perfect, even for their designed specially. The measure of their excellence is relative; it is the score of their showing against the enemy. Since not every aircraft type has been tried yet in every theatre -- some because they are obviously unsuitable, some because they are not available yet in sufficient quantities -- a full appraisal in their capabilities is not yet possible. It will not be possible until the war has been won, because, as it develops, new types and substantial modifications of old types will be thrown into action. But on the basis of 10 months of war, a fairly complete summary, subject to this limitation, can be made.

(1) The Navy went into the war with considerable quantities of aircraft that were not of the latest type and unquestionably suffered losses that could have been avoided had the latest equipment been available. But secret battle reports which have been examined by the Office of War Information show that the latest floating-base aircraft of the Navy are, when compared plane for plane with the planes of other navies, superior in all types.

(2) In battle areas in the Pacific where it has had its most complete trial, Army flying equipment hardly can be said to have had a fair trial in the early days of the war. The disruption caused by the surprise Japanese attack and the necessity of retiring to bases inadequate to the technical demands of aircraft operation imposed conditions that no aircraft could meet fully. Yet in the Pacific area, as in China, the over-all battle score of Army aircraft has been much better than the enemy's. This is not to say that it could not have been better still. If the services

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had been more on the alert for Japanese treachery or had more accurately forecast the performance and tactics of Japanese aircraft, if they had predicted the possibility of early hostilities with Japan and had been in a position to make timely preparation for it, then the showing would have been immeasurably better. If the necessarily slow process of better types could have been speeded, United States aircraft in the Pacific, especially fighters, would have been better fit for their jobs. As it was, the country paid in blood, and defeat for the determined blindness of its peaceful years. Even our bombers, performing superbly in retreat, could have done better if the past had given them a chance.

(3) In the vital European theatre, our newest fighters have not been fully tried up to now. Yet appraisal of our older lighter types -- the Bell P-39 and the Curtiss P-40 -- compels the conclusion that they are not right for operation under today's high-altitude tactics in England. Admitted deficiencies in their performance makes them unsuitable. Both are outclassed in the high-altitude field by the British Spitfire and the German Messerschmitt 109 and Focke-Wulf 190. But it is one of the apparent paradoxes of aircraft performance that the P-39 has proved a splendid weapon on the Russian and Aleutian fronts, and that the P-40 is a first-line fighter in Egypt, able to slug it out with the Messerschmitt 109 on substantially even terms. This is due to the peculiarities of the tactical situations in these theatres which will be discussed in more detail further on.

(4) Two newer fighter types, the twin engined Lockheed P-38 (Lightning) and the single-engined Republic P-47 (Thunderbolt), are in production and show great promise as high-altitude pursuit planes. Yet the public should be warned (a) that neither plane is the complete answer to the lighter problem (probably no plane ever will be) and (b) that neither has been tested adequately hi battle. Until they are, a complete judgment on their qualities must be withheld.

(5) The Army's four-motored bombers, as stated above, have proven superior in their categories in all theatres. The Consolidated B-24 (Liberator) recently has been fully tested in the European theatre and its splendid performance there and in other areas (notably the Middle East) and its general characteristics indicate that it will make a record parallel to that of the B-17 (Flying Fortress) wherever it is employed.

(6) United States medium and light bombers. part of the bombardment specialization peculiar to this country (as a result

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of its earlier preoccupation with defense of our shores only), are the best in the world. They have been tested in all theatres. United States scout bombers, product of the Navy's long-time development of this destructive art, also are without peers among single-engine dive bombers.

(7) The firepower and protection of United States fighting aircraft (guns, armor, and leakproof fuel tanks) are equal in all cases to the best our allies and the enemy have in the air, and in some cases are decidedly superior. In these necessities, brought forth by the war, United Stales aircraft were deficient when the war began in September 1939 and continued deficient for months thereafter. Conduct of the war by the British provided us with an effective proving ground. Many lessons learned by the British and the elaboration of some of their practices, particularly for airplanes built to their order by the United States, served largely to remedy the deficiencies by December 7, 1941.

It should be of great satisfaction to the American public that when these deficiencies were remedied, the job was done with armor and with guns previously developed in the United States by Ordnance experts of both. Notable in these developments was the .50-caliber machine gun, with its superior hitting power, range, and rate of fire, and the plane-borne cannon. In the latter field the United Slates' 37-millimeter gun is the heaviest piece of ordnance carried by any fighter in the world.

The Problem of Design

The designer about to build a new airplane type is, by rough analogy, in the position of a man with a fixed amount of money to be spent on a new and vital outfit of clothing. He has, say, $75 to spend, can use it all, but can get no more. Surveying his problem he considers the climate where the outfit will be worn, the nature of the work he is to do, whether in office or afield, the nature of the going he will encounter, whether on sidewalks, in mud, or over stones, during the day or night. For a severe climate he needs the best overcoat he can buy. But if he buys the $60 overcoat which is the best protection against the cold, he will have to get along with a cheap suit, and without accessories for his ensemble. If most of his time is spent indoors, he may want a $60 suit, but then his protection against the weather will be completely inadequate. So his purchases

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turn out to be compromises imposed by his funds. Either one of the elements is superior to all the rest, because of some specialized propose, or all are below the standard he would attain otherwise.

Expendable Horsepower
The strait jacket of the aircraft designer is the horsepower he has available. Given 1,000 horsepower, he can spend the surplus remaining after he has used what he needs to get his airplane into the air. It is this surplus that makes primarily for rate of climb. But as he also is ordered by the purchaser, i. e., the armed services, to build greater range into his airplane, he must spend some of his surplus to carry the weight of a greater fuel load. If armor must be added, more surplus is spent. There are other expenditures for guns and ammunition and perhaps light-bombs. When it finally flies in action. the plane, as all planes are, is a compromise. Lightly armed and armored, lightly built in its essential structure, it may climb with lightning speed, maneuver as nimbly as a swallow. But if it has been shortened of guns, it is a fighter of fancy footwork. without a killing punch. And if it is without protection for the pilot, if it is so lightly built that a burst of machine-gun fire will blast it apart, the plane is a fighter with a glass jaw, like the Japanese Zero. As a flying machine it is spectacular; as a fighting machine it is deficient.

If, on the other hand, the end product of the designer's work is heavily armed and armored and fitted with leakproof tanks, the plane will have a slower rate of climb and will not be so maneuverable as the lighter aircraft. It will have to rely on its speed, its heavier punch, its ability to absorb punishment when it gets within range of its nimbler adversary. Such a fighter is the P-40, and such is the direction toward which all the major warring nations save Japan have tended.

The reasons why, on altitude, the American P-39 and P-40 are inferior to some comparable allied and enemy types are many -- essential design, specialized purpose, armament, and armor are among them. But it is primarily due to another consideration that in its own specialized fighter class the P-40 has been demonstrably surpassed by comparable British and German planes.

This consideration is the quality as well as the quantity of the horsepower available to the designer. Two given engines may each develop 1,000 horsepower. One develops this output

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at 16,000 feel, let us say, and another at 20,000 feet. It is obvious that where it is of vital advantage to a fighter pilot to get on top of his adversary before attack, the engine with the 20,000-foot critical altitude ensures the better of two fighters designed for the same purpose. Up to ten or twelve thousand feet the planes may have the same performance, or the plane with the lower critical altitude may even be superior. But a fighter pilot would prefer the second to the first in any theatre where altitude is a deciding consideration of battle.

Air-Cooled vs. Liquid-Cooled
This brings up the question of the air-cooled versus the liquid-cooled engine and a problem of profound technical complexity which is far from final solution. The only liquid-cooled engine of American design now in mass production and general military use is the Allison. This drives the P-38, the P-39, and the P-40. Its development was late in starting and was carried on under great difficulties. It has not yet caught up with its opposite numbers, Britain's Rolls-Royce (also being manufactured in this country) and Germany's Daimler-Benz.

All three engines are liquid-cooled. When the last war ended, the United States had a reasonably good liquid-cooled engine -- the Liberty -- and went on to the construction of better power plants of this kind. Meanwhile, the development of the radial air-cooled engine bad been taken up with great skill and determination. The new-type engine had an appeal for the United States public because of its dramatic accomplishments. These began with the Lindbergh flight to Paris in 1927.

The air-cooled engine, inherently reliable, sturdy, and light, went into air-line equipment and into military bombers and fighters. Its future was assured because it enjoyed the subsidy of private and public enterprise. The result, United States air-cooled engines built by Wright and Pratt & Whitney are unequaled for horsepower output, ruggedness, and altitude performance, by any other nations power plants of the same design. These engines were not, however, specifically developed for fighter planes, as was the new German B. M. W. (Bayerische Motor Werke) in the Focke-Wulf 190. For small fighter planes the B. M. W.'s compactness gives it a notable advantage over other air-cooled power plants. The development of the liquid-cooled engine was all but dropped for a period of several years in the United States as a

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result of the ascendancy of the radial, air-cooled power plant. Although it seemed an ideal engine for single-seater fighters, both the armed services lost interest in it. The proponents of the engine found it first difficult, then impossible, to get from their superiors and from Congress the money needed to develop their project. Chief of these means of development was high-speed racing. The British, Germans, and Italians tested their liquid-cooled engine developments in the crucible of the Schneider Trophy race and other similar competitions. From these they learned invaluable lessons in design, which were tried in their turn in later competitions. But the United States, after a brief career in racing, withdrew. For a period of several years, development of the liquid-cooled engine was all but abandoned while the services concentrated on air-cooled engines. The Navy worked exclusively with air-cooled motors until recently. Meanwhile the Army had finally gone back to the development of the liquid-cooled engine because of certain desirable attributes, notably its adaptability to streamlining in small combat aircraft. But precious time had been lost. When war emergency orders called on the makers of the Allison for quantity production, the engine was not yet ready for its task. Suddenly recognized once again as an essential power plant for the well-balanced air force, the America liquid-cooled had lost ground that it has not yet regained.

The Supercharger
An informative side light on the priceless value of time in engine (and aircraft) development may be a brief discussion of the chief reason for the Allison engine's failure to become a world leader as of today. The reason lies in the engine's supercharger, a complicated device for furnishing air at sea-level pressure to an engine in the progressively rarefying atmosphere that a plane meets as it climbs.

When the first modern Allison was being manufactured for use in military planes, the minds of its makers and the Air Corps officers in charge of its development were on the turbo-supercharger. This is in effect a rotary 'air pump, separate from the engine but driven by its exhaust gases, which furnishes sea-level pressures to the carburation system far beyond the range of the integral supercharger. An exclusively American development, it promised great high altitude performance for United Slates airplanes. It has lived up to its promise in bombers and in the

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larger of the fighters, as will be discussed later. But in the smaller lighters which the Allison was to power, its incorporation in the design of the airplane proved, for that day. impossible. Technical difficulties, which could net be fully realized until it was tried in the air, blocked its use.

Thus time was lost -- an experience more or less typical in aeronautical design the world over. Meantime, less work had been done on the Allison's own self-contained supercharger than would have been done if its users and makers had realized they would have to depend on it and it alone. When development was resumed, the Allison was still further behind the parade.

Now, however, a two-stage, two-speed supercharger has been developed and thoroughly tested. This is an elaboration which in effect gives the pilot a high gear for his supercharger when his airplane has climbed beyond the best limits of his low-speed blower. Allison's power plants with this supercharger, regarded by the Air Forces as completely tested and proved, are being manufactured and flown and will shortly be in quantity production. They will vastly improve the performance of Allison-power aircraft and progressively step up its horsepower as improvements continue.

With the turbo-supercharger installed, notably in the big two-engined Lockheed P-38, the Allison engine lately has given a splendid service performance after months of tests during which all kinds of "bugs" developed and were eliminated, as was to be expected in a design which was new and unconventional. The result appears to be one of the best high-altitude, long-range lighters in the world. But the public is cautioned once again to remember that it has not vet been tested in combat and cannot be considered fully proved until it has.

Today, as we have said, the Allison engine after three years of wide service in the United States Army Air Forces still is a substantial jump behind its opposite numbers in the British and German air arms for altitude performance. Yet it is already a vastly better engine than many of its critics have made it out; few if any other liquid-cooled power plants are as rugged or as responsive to field maintenance. Since Pearl Harbor its horsepower output has been stepped up close to 40 percent, due to the research work done on the engine in the two or three years preceding our entrance into the war.

The British Rolls-Royce engine has improved at a parallel rate and still tops the Allison's horsepower output by close to 100

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horses so precious to a plane's rate of climb and altitude performance. But, with the turbo-supercharger, the Allison is rapidly gaining ground, While its direct competitors, British and German, are judged to have come close to the maximum performance of which they are capable.

In the liquid-cooled field, both services, with war emergency funds at their disposal, have actively encouraged and participated in the design of engines made by other manufacturers. Several of them show promise of excellent performance. Their tests in aircraft, which cannot be greatly foreshortened by any device known to science, will determine their suitability for use in battle aircraft. They are mentioned only to show that the development of the liquid-cooled engine in this country is fully alive again.

Thus, in the course of time, neglect in the United States of an essential power plant will have been made up. Such neglect is not unique, in the United States or in other countries. The British and Germans, in their need of fighter craft, stressed the liquid-cooled engine. It was not until a few months ago that the Germans brought out their first air-cooled first-line fighter, the Focke-Wulf 190. This German development illustrates again how difficult is the question of deciding upon either air or liquid cooled engines. The Navy's tried and listed Grumman F-4-F has an air-cooled power plant and so does the Army's promising P-47, although our Allies still have no first-fine fighter with this engine.

Aeronautical Design Slow
The basic specifications for United States aircraft now flying in combat areas were laid down five years or more ago, an indication of the slow process of aeronautical design in peacetime. Military and naval men were faced with a problem that the officers of many other major nations did not have to meet; they could not with any accuracy predict where the airplanes they were to build were to fight. Germany had a definite plan for employment of its aircraft then under test. So did Japan. So, for different reasons, did the designers of England. A striking proof of their conviction is the Spitfire, a splendid fighter admirable in all respects for the defense of France and, as it later proved, of England itself.

The prime specification for United States airplanes was that they would defend our shores. This, more than any other fac-

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tor, explains our preoccupation with long-range bombers, designed to fly high, fast, and far, to meet the enemy far from our soil and turn him back. We did not expect the enemy to reach us, or to fight him over his own territory. This partially explains our failure to develop, in time for the war's opening, a good interceptor, capable of climbing rapidly on short notice and intercepting enemy bombers. Our entry into the war without such an invaluable piece of equipment can he explained only by failure to give due consideration to the possibility of full American participation in aerial warfare overseas. Subsidiary explanations are shortage of development funds in peacetime years, the failure of a pivotal power plant (discussed above) to measure up to expectations, and the prevalent faith of the public that the country could avoid involvement in a foreign war.

In the vast revision of ideas of design after the war began in Europe, the United Stales owes a vast debt to the Allies, particularly to the British, and to the lessons they brought to America from the battlefield. Beyond their large orders for aircraft and accessories, which forced the building of substantial production facilities, the British also underlined the necessity for substantial changes in design and armament and dramatized their necessity by ordering the changes on their American-built aircraft. Notable among them are substantially heavier armor, a great increase in fire power, and the adoption, for bombers, of the power turret.

These improvements, already available because of American technical developments mentioned before, were on most of our aircraft and on all warcraft coming off the production lines when Pearl Harbor was attacked. One effect of the changes on our fighters, however, was that it loaded them down more than ever, gave them more protection and power but deprived them of nimbleness. It is illustrative of the fluidity of aircraft design that many United States fighter pilots now believe that the armor on their craft should be lightened and that they should have fewer guns.

Change is continuous. First the German, with his genius for speed and heavy hitting power, turned United States design into new channels with the accent on fire power and protection at the expense of nimbleness and rate of climb. Next the Japanese, who had developed his fighter craft in an opposite direction, set up a demand for the highly maneuverable, fast-climbing pursuit plane.

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The Influence of the Tactical Situation

In public discussion of the performance of United Slates aircraft in this war, little notice has been taken of the effects of the battle situations into which they were thrown. The point already has been made that few if any designers of American airplanes envisaged, or were either asked or permitted to design for, a war in which United States aircraft would be called mom to defend Britain, or that bombers would have to be operated in short-range missions against objectives that once were Dutch, Belgian. and French. Thus the fast-climbing interceptor aircraft was almost completely neglected, and bombers were designed to carry medium loads over long distances rather than great loads over short distances.

Fortunately, the British were working toward the ends which we had neglected because items of greatest importance in their defense were of minor importance in ours, as it was then conceived. The result is that the United Nations now have a fairly adequate selection of aircraft of all types. But it is not, nor is it likely to be, superior to the enemy in all categories. The best that the public can expect, and the best it will get, is that on average the equipment of the allied air forces shall be superior to the equipment of the enemy.

The effect of the tactical situation on the performance of aircraft operation is most strikingly demonstrated in the performance of P-40 fighters in the losing battle that began with the attack by the Japanese on the Philippines and ranged down through the South Pacific, through defeat after crushing defeat until at last a stand was made in Australia and southern New Guinea. Through the bitter days of the battle in Java, and tine first weeks of the light in Australia, P-40's performance was decidedly less than standard for its own capabilities. The odds against any other record were overwhelming. One reason was that many of the pilots in the area of retreat were new and untried and that they faced veteran airmen. But a more decisive reason was the fact that in retreat the loser progressively is deprived of the installations vital for successful combat operation. Operations were from makeshift fields. Repair and overhauling facilities were at a completely inadequate minimum.

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Inadequate Air-Raid Warnings
Most disastrous of all was the complete lack of air-raid warning systems. In the Philippines the system carefully set up was disrupted by fifth-column agents before it had once functioned. As the battle wore south there was often none at all. Furthermore, our fighter pilots were without the technical equipment -- detectors, etc.- to prepare themselves for the approach of the enemy. The result was that in many raids the first notice came when the enemy's planes were sighted. If our fighters were ready in the air they had a fair chance of getting up and doing battle with the enemy or, as happened more often, of waiting for the enemy pursuit to come down to them and then slugging it out.

With this great deficiency in the preparation for air war, no pursuit airplane ever built could completely have overcome it. It is too late to start a climb to victory when the bombers are overhead. Undoubtedly the P40's could have given a better account of themselves if they had had a higher rate of climb and adequate warning system, or a better altitude performance. On the other hand, our losses in men and planes would have been far greater had they not been equipped with their heavy protective armament and high fire power.

How such equipment can be well employed with adequate warning service was illustrated by Brigadier General Claire Chennault's A. V. G. flyers in China. Buttressed by one of the finest air-raid warning systems in the world, his pilots scored the destruction of 218 Japanese planes, including many Zeros, while losing only 84 of their own. (Their personnel losses were much lower because of the protective values of the P-40.) The score was made by P-40's of an older type than the planes now in service. A. V. G.'s successor, the present pursuit group of the Army Air Forces in China, likewise under command of General Chennault, is making a record that is at least as good in every particular. It must be repeated that all the credit does not go to the pilots nor to the planes: a great part of it is due to the warning system.

The other side of the picture is shown by the destructive Japanese raid on Port Darwin, Australia, in February 1942. The first notice our limited number of pursuit pilots had that fine raid seas on was the sight of the Japanese bombers and pursuit screen in the sky. Five of our 10 P-40's were already air-borne. The other

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five immediately took off. One of our planes was shot down by three Zeros as it crossed the border of the field. Another, just behind him, shot down a Zero before he had had time to retract his own wheels, was in turn shot down and parachuted to safety.

In that brief, destructive attack, while the Japanese bombers were blasting allied ships in the harbor, we lost eight of our ten P-40's. Only the armor in the planes and the fact that our flyers were fighting over their own territory cut the loss in the pilots to four.

Our Score Improves
How the favorable change in that nearly impossible tactical situation has altered the performance of our planes is best shown by recent events. On August 23, a force of 27 Japanese bombers and 20 Zeros attacked Darwin again. Our P-40's, now adequately forewarned, intercepted them. They shot down four bombers and eight enemy fighters and forced the rest to jettison their bombs. Not a single United States pilot was lost. After the first shock of the surprise attack had been absorbed, United States effectiveness against the enemy immediately improved. For example, from recent battle history in the Solomons, the Navy's F-4-F's knocked down 42 Japanese aircraft in four days without loss to our own force. A dramatic increase in the destructiveness of Army aircraft has, meanwhile, been continuing.

Thus from February 1 through September 20 Army planes (including our bombers) destroyed 270 enemy planes on the Asiatic and Australian fronts; our losses were 114 planes (and a lesser number of fighter pilots). For the month of August a great improvement over this good average was shown -- enemy planes destroyed, 75; United States planes lost, 15. In that month it is interesting to note that the score of the P-40's was 18 to 2; the P-39's score was 20 to 5. As this is written, the Army Air Forces are engaging the enemy around the world. It is consistently piling up a plus record.

A superficial deduction from this would be that there is not much use worrying about the quality of our fighter aircraft. Again, it would be an oversimplified conclusion. The fact is simply that under the tactical situations now existing in the South Pacific, in China and in other theatres, and with the improving methods of employment of our fighter craft, the score of United States pursuits has been on the winning side for months despite

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seemingly overwhelming numbers of the enemy. The average is improving. But this does not mean that we have won a decisive battle or gained permanent ascendancy in the air. A new and secret type of enemy airplane, a shift in enemy tactics which would force us into different battle conditions, could change the picture once again. All of us must keep such possibilities in mind. In this, as in all other wars, only complete victory is decisive.

In contrast to their unsuitability for high-allitude service in Britain, P-39's and P-40's have shown on the record that they are valuable weapons in Russia and in Northern Africa. Again the explanation is in the tactical situation. Both are battlefield areas. The duties of aircraft in battle, where a great part of air force is used in support of ground troops, draw them down below the levels at which they would operate if working as independent air power. A battle situation calls for a predominance of low-altitude work by dive bombers, bomber-strafers. and army cooperation craft of all descriptions including low-flying pursuits. To situations of this kind the heavily armed and armored P-39 and P-40 are well suited. Their deficiency in altitude performance does not count heavily against them. Thus in the desert the P-40 long has been, and still is, a first-line pursuit weapon. With its latest improvements, it probably is the most efficient fighter in the desert. One of the apparent oddities of its employment in Africa is that it can compete on equal or superior terms with the German Messerschmitt. with which it could not adequately cope in the high altitudes of the European theatre. Similarly its African performance has been as good as the justly famed Spitfire and in certain tactical situations better. In the similar situation on the Russian front, the cannon-carrying Bell P-39 has been employed effectively by our Allies. The Russians report that it has turned in a crack battlefield performance, even besting the cream of the Luftwaffe's pursuits in the air. Details of its performance are lacking, but the assumption must be made that the encounters are at relatively low altitudes to which level German equipment is forced in order to do an adequate job of cooperation with ground troops or a satisfactory job of attack on Russian ground units and establishments. Similarly, in the Aleutians the strafing power and range of the P-39 have node it one of the most valuable weapons, particularly in attacks on ships, submarines, and Japanese ground establishments.

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A Few Notes on American Types

As indicated before, probably the most highly specialized combat type is the fighter airplane. As engineers now know design, no fighter can be the best in all things. Another determinant of the fighter's pivotal influence is the engine and its supercharging equipment.

The problem may be stated roughly as follows: A power plant which develops its maximum horsepower at low altitude will lose its effectiveness as it passes the critical altitude and the performance of the plane in all its flying functions -- speed, climb, maneuverability -- will progressively fall off. An engine which develops its maximum at high altitudes, e, above 25,000 feet, will have inferior performance at the low levels. This is because the full force of its supercharging equipment cannot be used at the low levels -- except for short periods of so-called "flash performance" -- without overtaxing the engine and sending it toward complete mechanical failure.

Thus the possession of a crack high-altitude fighter does not mean mastery of the air. For complete domination, we need fighters capable of maximum performance at possibly three levels -- sea level to 15,000, 15,000 to 25,000, and above 25,000. Probably we never will be unquestioned masters at all these levels (which are arbitrary figures only). Other variants in performance -- e. g., plane design, load, and variation in power plant -- will and do make for overlapping performances.

Specialized Pursuit Ships
The struggle in pursuit design is for supremacy at all levels, and until we can seize the offensive and force the enemy to fight at our most favorable altitudes we shall have to continue our engine and aircraft development relentlessly and skillfully. This we are doing. The Germans have been notable in recognizing the same fact and in acting upon it. The most recent example of this is the Focke-Wulf 190, a splendid pursuit plane powered with a specialty designed air-cooled radial engine For laymen who thought that the only struggle in the flying qualities of pursuit was for altitude, the Focke-Wulf 190 would be a technical disappointment. Close laboratory and flying studies of a captured model distinctly show that it is a middle-altitude performer. Like some of our own fighters (notably the Navy's Grumman F-4-F) it is equipped with a two-stage, two-

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speed supercharger. Thus it has enough flexibility to operate at great efficiency through an overlap of two of the levels named above. Below 10.000 feet it has a spectacular rate of climb which falls off radically as it reaches the altitude limits of its low-speed supercharger. When the second speed is engaged, it regains its sea-level rate of climb and holds it handily until it reaches 18,000 feet. From that altitude on, it has passed the limits of flexibility that the two-speed blower gives it, and its performance falls off rapidly. Its design is specific recognition, by a technically proficient engineering and flying group, that pursuit is still bound down by the necessity of specialization and that it will be so until radically new power and propulsion techniques have been developed.

The following descriptions of the most important United Slates warcraft now in service are not intended to be full or technical, but a summary for laymen of their records. In setting them down some repetition of observations already made is necessary. It will be noted that only passing reference will be made to types not yet in service, In this connection a few observations are in order, since many contemporary critics have a weakness for considering in their estimates the performance of aircraft not yet in service. A typical instance was the recent listing by a British writer of the 12 best aircraft types, as he saw them. Of seven American aircraft included in the list, two have not yet participated in battle.

Presumably this critic concluded that because both craft had been widely publicized more than a year ago, both must by now have had their battle test. The mistake could be charged as much to us as to him. In the unrestricted days of peace we were too ready to make the agile leap from the test of the prototype of a new aircraft to the day when it began rolling off the production line for service. Now we know. And now we are keeping secret the performances of our new aircraft lest we give information to the enemy. The current practice has another, equally important effect -- it stops wishful thinking which up to now has given the public a distorted idea of just how far, technologically, our battle aircraft have gone.

The best that can be said of the future is that the United States aircraft industry and the services are in an orderly ferment of developing specialized aircraft of high, and in some cases sensational, promise of battle performance. Some of them actually

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are flying, and, for some, production has begun. The temptation to all familiar with them is to make public the great hope they give for the near future. Some such promises are likely still to be made because it is human to look into the future. When they are made, the public should scan them with one thought in mind -- until planes are battle tested. they cannot be called proven. And no sound appraisal of their effect in the war can be made until they have been proven. Where reference to development for future planes is made in the notes below, they should be scanned in the same light. Some have passed their tests in the laboratory and in the air, some are still to be tested with great promise of success. But full judgment must still be reserved until the ultimate test is made.

Fighters
Curtiss P-40. Single-engine, liquid-cooled. Most discussed of all United Stales combat aircraft, this tighter has gone through six major type changes (from P-40A to P-40F). Types now in wide use are the "E" (Kittyhawk) and "F" (Warhawk). Substantially improved through each change, it has the virtues of heavy hitting power, excellent armor, high diving speed, and leakproof tanks common to all United States combat aircraft. Against the Zero it has proved on average to be superior. The Zero's advantages of fast climb, great maneuverability, and better ceiling are offset by its vulnerability and the fact that when a Zero goes down its pilot almost always goes down with it. He is riding a lightly built aircraft, highly inflammable -- since it has no leakproofinig and is without armor protection. It is not this poorly protected Zero fighter that American pilots prefer. But most P-40 pilots frankly say that they would like more altitude, if they could still maintain their advantages of superior firepower and protection.

Bell P-39 (Airacobra). Single-engine, liquid-cooled. A part sharer in the criticism heaped on the P-40, the P-39 has roughly the same limitations and the same positive virtues. Developments now being made in this design give the promise of much improved performance while retaining all its virtues, including splendid visibility for the pilot in missions cooperating with ground troops. Armed with a cannon as well as machine guns, it is also a powerful ground-strafing craft.

North American P-51 (Mustang). Single-engine, liquid-cooled. Newest of the Allison-powered United Slates pursuits, the P-51

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has been quietly developed. It did not come prominently into public notice until the British had used it in the raid on Dieppe. One of the fastest fighters in the world, it has roughly the same limitations on altitude performance of other single-engined Allison craft. Improvement in the power plant (treated above) and other technical changes promise a sensational improvement in the altitude performance of this airplane.

Lockheed P-38 (Lightning). A two-engine, liquid-cooled pursuit plane, the P-38 has so far had only limited tests in action, notably in the Aleutians. Its performance has been brilliant. Turbo-supercharged, it has excellent high altitude performance. Its long range (exceeding the range of the Spitfire, Messerschmitt 109, and Focke-Wulf 190) and its great fire power give it real promise as an escort to our high-altitude bombers. At its best altitude it is one of the world's fastest fighting aircraft. Nevertheless, constant improvements are being made.

Republic P-47 (Thunderbolt). Powered by one of the largest United States air-cooled engines, the P-47 has been thoroughly tested, is in service and in production. It is turbo-supercharged, heavily armed, and has a greater high speed than the P-38 at extreme altitudes. Its trial by battle is not far off.

Grumman F-4-F (Wildcat). The Navy's standard fighter, as of today, the F-4-F is unquestionably the best carrier fighter now in battle service. Powered with an air-cooled engine, with two-speed supercharger, it has shown altitude performance that comes close to the Zero. Its slower rate of climb and maneuverability are offset by its characteristically heavy armor and armament. Designed primarily for carrier work, it has folding wings for compact stowage. Like most such specialized installations. this feature steps up the weight of the F-4-F by 5 percent and thus cuts down slightly on its performance. The sacrifice is heavily overbalanced by the fact that it increases a given carrier's complement of fighters by 50 percent.

In the Solomons, F-4-F's operating against Japanese fighters and bombers have been destructive and in many encounters decisive. Yet superior replacements for the F-4-F are already in production.

Heavy Bombers
Boeing B-17 (Flying Fortress). A tried and thoroughly tested model with an unequaled combat record (four engines, air-cooled turbo-supercharged), the B-17 is essentially a high-alti-

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tude, long-range bomber designed for precision destruction of restricted targets at great ranges. Often compared, sometimes unfavorably, with the British Lancaster, it is not in the same category. While it is primarily designed for day bombing, it is easily convertible in the field for night bombing at lower altitudes and shorter ranges, with greater loads. This dual function is not possible with the specially designed, slower night bombers. The Lancaster is designed for night bombing, hence has much less altitude and speed performance, but is capable of carrying a heavier bomb load on short and middle distance missions. In its armament equipment, the B-17 has been most inaccurately characterized as deficient. The fact is that it is one of the most heavily armed bombers in the world. It has indicated by its work in the Pacific and over Europe as well that it can carry out high altitude day-bombing missions under the protection of its own guns and without fighter escort. Gunners in Flying Fortresses have shown that its destructive, high-rate .50-caliber machine guns have greatly extended the effective range of the bomber's defensive fire.

Consolidated B-24 (Liberator). Another four-motored, air-cooled bomber. turbo-supercharged like the B-I7 and capable of operation at high altitudes and over great ranges for high-accuracy bombing missions. In the Pacific, in Northern Africa, Europe, and the Aleutians the B-24 has shown itself a topflight performer, capable of duplication of the B-17's record.

Medium and Light Bombers
North American B-25 (Mitchell). A long-tested (two-engine, air-cooled) aircraft of speed, long range, and good load-carrying characteristics, chiefly dramatized for the United States public by the raid on Tokyo. No airplane of the same class in friendly or enemy air forces is known to equal it.

Martin B-26 (Marauder or Martian). Two-engine, air-cooled. This is also a battle-tested plane in general comparable with the characteristics and performance of the B-25. No nation but the United States, so far as is known, has so efficient a plane in its class.

Douglas A-20 (Boston or Havoc). A light (two-engine, air-cooled) bomber widely used by the British in the European and Egyptian theatres. Flexible in its performance, it has also been employed with modifications as a heavy lighter. It is unquestionably one of the best in its class.

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Douglas SBD (Dauntless) (Army counterpart A-24). The Navy's carrier-based standard dive bomber (single-engine, air cooled), this craft is the best in the world in its category. As a land-based craft it nay find its equal or even its superior in the Germans' latest Dornier and Junkers multimotored craft. It will shortly be supplemented by a newer design now in production.

Douglas TBD (Devastator). The Navy's standard torpedo bomber when we entered the war, this single-engine, air-cooled aircraft was as good as the best in service in tiny Navy. Yet development already under way soon caught up with it and it is being replaced by the -

Grumman TBF (Avenger). Single-engine, air-cooled. This plane made its battle debut at Midway. A bigger, more powerful, and in all respects more advanced airplane, the TBF is the best carrier-based torpedo plane so far seen in action in the war.

Patrol, Reconnaissance, and Miscellaneous
In this field, United States development has been satisfactory in quality. The Navy's patrol bombers are the equals of any in the world, and in range (the basic necessity of the work of such craft) they are probably superior. One of the Navy's types, the famous PBY, has been criticized for lack of speed. Such craft are not built for speed but for ability to stay long hours in the air and to land on rough water for refueling and servicing. In these capabilities the PBY is a superior aircraft. Its employment, however, is now overshadowed by later types, notably the new Consolidated and Martin patrol boats.

In the Army Air Forces the requirements of a plane for every task have brought into the military field many aircraft not mentioned in the foregoing summary. They range from troop carriers and transports down to the "grasshopper" planes for liaison, fine artillery fire adjustment, etc. These types are very good, on the average, and many of the newer craft are definitely superior to comparable equipment in other air forces. Rising production in this general category should give the United States Air Forces the best equipment of thus kind in the world.

Can the Pace Be Maintained?
Earlier in this report it was stated that on average the combat performance of United States' aircraft was good. In the past

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two months it has been more than that -- in many theaters, notably the Solomans and Australia, it may have been too good. That is to say, due to unusual tactical situations and other considerations, the pace may well have been too fast to be kept up. In this war, the United States has just begun to fight. In the months to come battles may be lost and crushing defeats may be suffered. It seems certain that our offensive activity is stepped up, casualties will increase and the losses in aircraft will rise with the spread of our participation.

This the public must realize, and for this it must be prepared. Against the proficient German Luftwaffe we have yet been only slightly engaged. Against the Japanese our offensive has only barely begun. When we meet reversals and the pull to victory seems to grow long and hard, Americans will do well if they indulge to the full their genius for critical self-analysis.

The information in this publication is valuable to others. When you have finished reading it, please pass it on to a neighbor or friend for further circulation.

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U.S. GOVERNMENT PRINTING OFFICE: 1942