Evolution of the Liaison-Type Airplane 1917-1944, Army Air Forces Historical Studies: No. 44, produced by AAF Historical Office, April 1946.

A detailed look into how the U.S. arrived at the point where a diminutive airplane, collectively known as L-birds, or liaison aircraft, became some of the most imposing forces in the Allied victory of WWII.

Forward

This study of the liaison airplane was written in the Air Technical Service Command Historical Office by Capt. Irving B. Holley, Jr. The history is focused primarily on the evolution of the idea of the liaison airplane as distinguished from the observation airplane, and emphasis is placed on the problems of isolating and identifying the growth of this concept rather than on the liaison airplane as a continuous engineering development. Engineering details are discussed only when they were factors that influenced and delimited the evolution of the concept. In short, the history is concerned with the gradual emergence of a clear understanding of specific tactical functions for the liaison airplane. When this had been gained, it was possible to establish engineering objectives.

Chapters include:

  • Heritage of World War I, 1918–1929
  • Evolution of the Observation Airplane, 1929–1937
  • The Observation Airplane in Use, 1927–1937
  • Lighter-Than-Air Experiments and Autogiros, 1930–1940
  • Light Planes and Slow Planes, 1929–1938*
  • The O-49 [L-1 Vigilant], First of the Liaison Airplanes, 1938–1940*
  • Lessons Learned From the European War and From maneuvers, 1940–1941*
  • The Liaison Type is Recognized, 1942–1944*

(* Denotes excerpted here.) [Frequently quoted Air Technical Service Command 452.1]

Chapter V – Light Planes and Slow Planes

The history of Air Corps interest in light airplanes dates back as early as 1929, when the Materiel Division conducted an extensive survey to determine the possibilities of using light commercial aircraft in lieu of existing specialized training equipment. Despite the fact that 40 manufacturers expressed an interest in the project, the division found only one model which was at all suitable. All others contained objectionable features, for the most part structural members which did not conform to Army-Navy materials specifications. Taken collectively, the utter lack of standardization and interchangeability presented a most serious objection to the use of commercial aircraft for military use, and the division gave up the idea.

One of the manufacturers of light-weight airplanes, the Taylor Aircraft Company, had no intention of abandoning the military market for training airplanes. Writing to the Assistant Secretary of War for Air late in 1931, Taylor pointed out that light-weight airplanes had dropped in average price from $5,000 to $3,500 between 1930 and 1931 and predicted that in another year the light airplane would be outselling all other types. Stressing the favorable economy of cub airplanes selling at $1,325, Taylor urged the war Department to consider the cub as a trainer, saying: “If some of these Army contracts were passed around to the manufacturers of light airplanes, it would greatly strengthen their position.”

Outcast and Unwanted

The Materiel Division had no interest in strengthening the position of light-airplane manufacturers, and brushed off the Taylor proposition with the remark that parachutes and heavy, winter flying equipment made the use of small airplanes impossible. Just why cadets in preliminary flying training should be wearing heavy flying clothing was not explained, but the division reply was emphatic, that the small airplane had no place in the Air Corps training program.

When Taylor renewed the attempt to sell the idea of light training in 1935, the Materiel Division replied that the “present program” did not call for light airplanes, that all airplanes were procured in competitions, and that the division would be glad to include Taylor on the list of manufacturers receiving circular proposals. The manufacturer pointed out that there had been no intention of competing with existing standard equipment. Taylor had hoped to interest the Materiel Division in a project to experiment with light-weight airplanes for preliminary training quite apart from existing practices.

The Baker Board [under President Roosevelt, War Department Special Committee on the Army Air Corps headed by former Secretary of War Newton D. Baker] in 1943 recommended the use of small, inexpensive, “non-military” airplanes for training purposes. The Assistant Chiefs of Staff G-3 and G-4 and the Chief of the Air Corps disagreed with the report, but the Chief of staff pointed out, by way of comparison, that the Coast Artillery used subcaliber practice guns successfully and directed the Air Corps to investigate the use of light training airplanes.

The Materiel Division had marshaled a number of arguments against this directive. Light airplanes introduced increased supply problems; they could not carry the “necessary equipment”; they did not conform, in general practice, to Army standards in strength factors, flying characteristics, etc.; and finally, they could not be put to “military use.”

The Light Airplane as Experimental Trainer

It was not until 1938 that the Air Corps pressed the question further. General Westover, then Chief of the Air Corps, raised the issue once again, in noting that commercial flying schools were using light airplanes successfully. The Materiel Division took steps to procure a number of commercial models “off-the shelf” to test them experimentally at the Training Center. Type specifications were prepared, and the division circularized the commercial flying schools to garner all available information on the use of light airplanes.

It is significant that more than 10 years earlier the British had begun using De Havilland Moths with 80 hp. engines as an economy measure in trainer airplanes. Something of the prevailing attitude in military circles is reflected in the report of the Military Attaché in London that “These planes have no tactical value, but are intended for communications and transportation purposes.” World War II experience was to demonstrate how wrong that opinion had been, and the attitude represented by such expressions was to account for the fact that the Materiel Division was forced to accept, partially satisfactory airplanes when tactical requirements made large-scale procurement of light airplanes an urgent necessity. In Europe, however, the light airplane had long been accepted as a military instrument.

De Havilland DH.82 Tiger Moth

Reporting on the French Army exercises of 1932 the Assistant Chief of the Air Corps noted that “the important feature of the maneuvers, from an aeronautical point of view, was the use of, reserve personnel.” Small, touring aircraft, piloted by their owners, members of the air reserve, were used for staff and command liaison agents and couriers. Government bonuses and subsidies encouraged owners of light airplanes to participate.

It was no accident that the French were using light airplanes as well as more conventional, high-performance aircraft. French military doctrine encompassed the utilization of light airplanes. An engineer writing in L’Aerophile in 1935 called speed the “queen quality of aviation” in all save observation and army-cooperation aircraft, where other factors were more important.

The course of instruction for French air units assigned to the army corps considered the specific problem of observation equipment in detail. After noting the disparity between the absolute necessity of close liaison between command posts and observation airplanes and the improbability of finding adequate airdromes for high-performance aircraft in the vicinity of command posts, the French text suggested the feasibility of utilizing light, unarmed, staff airplanes to help take over the forward-area liaison function.

Seeing Is Believing

In Germany too there was general recognition of the importance of light airplanes. In fact, the Germans had gone so far as to perfect a special, slow-flying airplane capable of extremely short-run take-offs for the express purpose of forward liaison and observation. In September 1937, the U.S. Office of Naval Intelligence quoted the Völkischer Beobachter account of an episode in the German infantry maneuvers at Stavenhagen, east of Lake Malchin, where Generals Milch and Udet flew up in a Fieseler Storch which landed in a 20-meter run. General Udet, described the machine as “the airplane with the record for slow speed.”

Its “unsurpassed” landing qualities made it independent of an airdrome, a quality which, in conjunction with its potential high speed for escaping hostile attack, led the German paper to comment: ”One can easily imagine how important this new construction will be for the tactical scouting flight.” Easy as it may have been for the Germans to imagine a light, unarmed, slow-flying airplane in a tactical role, there were a number of military minds which found such a thing extremely difficult to visualize.

Fieseler Fi 156 Storch

The Storch, the German Air Force’s Fi-156, was built by the Fieseler Flugzeugbau at Kassel-Bettenhausen. It was a three-place, tandem, steel-tube airframe powered by a 250-hp. Argus engine. Its wings, spanning approximately 48 feet, could be folded back for road travel and ground concealment. Despite the fact that the airplane had a low speed of only 32 m.p.h., its high speed was around 115 m.p.h. A wing loading of 9 1/2 pounds, in conjunction with slots and flaps, made possible landing runs conservatively estimated at 92 feet, a high figure in the light of eyewitness accounts of the Storch’s performance. All this information which had been gathered by Naval Intelligence became of peculiar significance in view of the reported military use which the Germans were making of the new airplane as a liaison aircraft for tank corps commanders, for artillery fire control, and for road control of mobile trains.

There was nothing exceptionally covert about German plans for using the Storch. It was demonstrated at the International Aviation Meet in Zurich, where Fieseler himself flew the airplane in competition with autogiros to show that it could land and take off in a shorter run than that required by the typical autogiro. The tactical potentialities of the Storch may have been realized by the Germans, but the U. S. Military Attaché in Paris was unimpressed. He commented: “A useful communication aeroplane, but not of great interest beyond this; a sort of Gugnunc [Handley Page H.P.39], as far as I can judge, with no really original features.” If the Attaché spoke disparagingly, the Germans were not listening. In 1937 there were 120 Fi-156 “observation airplanes” on contract. In 1938, 50 of these airplanes had been delivered and Fieseler was producing them at the rate of one a day. The model was still in production in 1939, when the Storch was used extensively in the Polish campaign.

Handley Page H.P.39 Gugnunc

If the attaché at Paris failed to see the importance of the Storch, its implications were not entirely lost on those who studied intelligence reports in the United States. The General staff informed the Chief of the Air Corps that although foreign observers had indicated that autogiro tests were proving disappointing, the German Air Force had been successful in developing a slow-flying airplane with military characteristics approximately equal to the autogiro characteristics approved by The Adjutant General in August 1936. The Materiel Division was confident that it would be possible to develop such an airplane along conventional lines, using accepted and proved principles.

Slow-flying airplanes were not unknown in the United states. The Guggenheim Safe Airplane Competition winner of 1930, the Curtiss Tanager, a conventional airplane with slots and flaps giving it a speed range between 30 and 110 m.p.h. with a 176-hp. engine, was well known at the Materiel Division, but there was a great deal of difference between knowing of the slow-flying airplane and visualizing its tactical potentialities. When the General Staff directive regarding slow-flying airplanes reached the Materiel Division, a survey was made to compile flight data on 22 light, commercial-model airplanes from such manufacturers as Aeronca, Fairchild, Rearwin, Ryan, Stearman, and Taylor. The results were not impressive. Apart from paper claims made by the manufacturers, the performance characteristics fell below those of the Fieseler Storch.

Curtiss Model 54 Tanager

Among the many slow-flying airplanes considered at the Materiel Division, the Crouch-Bolas was perhaps the most novel. The Grouch-Bolas principle, first suggested for pursuit airplanes in 1936, achieved a high degree of lift in power-on landings by passing the slipstream over as large a portion of the wing area as possible. The Crouch-Bolas Dragon Fly, “capable of operating from highly restricted and unprepared areas” over a large speed range, seemed to offer an ideal compromise between the conventional observation airplane and the autogiro.

Crouch-Bolas Dragonfly

Changing Perceptions

The Chief of the Air Corps circulated the Crouch-Bolas “courier-observation” airplane idea to the General Staff (G-3 and G-4), as well as to the chiefs of Infantry, Cavalry, and Field Artillery. The consensus of replies to this proposition seemed to favor experiments with the type, but more important, it was suggested that observation squadrons be formed with a small number of high-speed observation airplanes and a large number of slow-flying airplanes. The trend in observation aircraft had already begun to change. Perhaps even more important, the Chief of Cavalry went so far as to break with accepted doctrine in noting that the slow-flying airplane need not have armament. He visualized mechanized warfare in which staff officers, observing from the air, would actually land near congested road columns to give instructions.

The Materiel Division did not favor the Crouch-Bolas principle. Reiterating an earlier statement, the division agreed that it would be wiser to develop a slow-flying airplane along conventional lines after proved principles. Such an airplane could be procured, the division claimed, within a year, while it would take “at least two years” to develop an airplane along Crouch-Bolas lines. This attitude was primarily a result of the conclusion that the principle of power operation in the low-speed range would be fundamentally unsound. The Dragon Fly idea, like the autogiro experimentation, did not entirely lead up a blind alley, however, for despite the fact that no immediate procurement resulted from the project, the interest expressed by the ground arms was probably worth the discussion.

By the end of December 1937 it was apparent that whatever promise the autogiro might hold tor the future, it was not at the moment sufficiently perfected to be put into production. Unfortunately, few funds were available to press experimental work vigorously. A similar situation prevailed in the case of the slow-flying airplane. The type held great promise, but no single model had been perfected for military use, and in 1937 the fiscal future, as far ahead as 1939, offered no funds for development work. The Chief of the Supply Division suggested that $100,000 be earmarked in FY 1940 funds to develop the “light courier type,” in line with existing policy which contemplated service testing the autogiro in competition with the slow-flying airplane. This plan anticipated a decision between the two by 1942, when a production-model competition could be held for the most suitable type. This was sound and progressive planning in terms of normal peacetime Air Corps developments, but in Europe the tempo of progress was no longer normal.

The technical assistant in Europe of the National Advisory Committee for Aeronautics (NACA), J.J. Ide, continued to prove his worth by confirming and supplementing the information of the attachés. After describing in detail the Fieseler Storch with which the Germans “startled the Zurich Meet,” Ide identified a significant European trend when he stated: “High performance army cooperation and observation airplanes are almost non-existent.” The direction of observation-airplane development had already been set in Europe, but nearly two years were to pass before the impact of this trend would strike with all its implications in the United States.

The Storch, however, continued to influence thinking in military circles. On learning of Materiel Division interest in slow-flying airplanes, the director or aeronautical research of the NACA sent the Engineering Division chief a copy of a Handley-Page bulletin on the Fieseler airplane. At about the same time intelligence reports revealed that German Panzer divisions anticipated attaching Storch observation squadrons to the Panzer organization, consisting of 11,000 men and 3,000 vehicles.

Three Times Persuasive

Perhaps the most telling influence of the Storch came somewhat later when a Fieseler model flew at the Cleveland Air Races in competition with an autogiro. Materiel Division representatives were so much impressed by personal observation of the Storch in action that the division chief asked OCAC to arrange for the aircraft to be brought to Wright Field where the airplane was inspected in detail by Aircraft Laboratory personnel. The Storch’s performance was convincing, but even before it came to Wright Field, the Materiel Division had been perfectly willing to admit its tactical value.

By the end or January 1938 the Materiel Division suggested that there seemed to be no need for a formal design competition of slow-flying airplanes, since physical articles approaching the desired characteristics were already available. In line with Expansion Program policies, the division recommended that a circular proposal be prepared for a production model slow-flying airplane if funds could be found somewhere in 1939 allocations.

Liaison Type Technical Approval

Probably the real landmark in the evolution of observation airplanes came in March 1938 when The Adjutant General formally approved the Air Corps’ military characteristics for the observation airplane, a “short range liaison” type, a two-place single-engine aircraft with an assigned mission of artillery fire control and liaison function for ground commanders. It was contemplated that performance characteristics for the new type would include a speed range from 40 to 125 m.p.h., the ability to clear 50-foot obstacles in a run of 500 feet or less, and, most significantly, no armament. The World War I heritage of observation aviation was beginning to break down into its component functions. From this point on, the development of liaison aircraft became a foregone conclusion, but a great distance lay between the decision to develop the type and the actual tactical use of the type in large quantities by service units during World War II.

Chapter VI – The O-49, First of the Liaison Airplanes, 1938–1940

General Arnold touched on the very core of the observation airplane problem when he said, in an address before the Society of Automotive Engineers in November 1938: “This type has now reached a point where, due to its high performance, it is unsuitable tor some close support missions.” The gradual but continual progress in aviation since World War I had brought about a change which made inevitable a drastic alteration of observation airplane policy. The relatively low-performance airplanes of the earlier war had been able to perform such extremes in function as infantry liaison and tactical reconnaissance deep into hostile territory, but during the following 20 years, as speeds increased, the multipurpose observation airplane became an anachronism. The trend of thinking was clearly defined when General Arnold said: “Those of you who saw the exhibition at the Cleveland Air Races join me in believing that these slow speed liaison airplanes may prove to be more practical than the autogiros which the Army is now service testing.”

In all probability, the Air Corps’ failure to perfect the organization and equipment of its observation squadrons was a direct result of the lag in shaking loose from the World War I concept of aviation as a tactical adjunct of the ground forces and in establishing airpower as an independent, strategic weapon. It was almost inevitable that the effort to enlarge the strategic role of air power should lead to the neglect of army-cooperation and observation functions. Almost exactly the same difficulties appeared in France and England, where the creation of separate air forces developed a whole series of similar liaison problems.

Close Support of Ground Troops

By 1938, however, the Air Corps could no longer neglect the question of observation aviation. Even if the current of events in Europe had not forced the development of slow-flying airplanes, a General Staff directive made it mandatory for the Air Corps to concentrate on army-cooperation equipment. After pointing out that the infantry division continued to be “the basic combat element by which battles are won,” the General Staff directive stressed the fact that the Air Corps was to press the development of equipment “for the close support of ground troops to the same extent that now pertains with respect to types suitable for strategic and more distant missions.” Between pressure from the Army and the spectacular performance of the Fieseler Storch, the Air Corps could scarcely avoid the decision to speed the perfection of liaison aircraft.

Nevertheless, the decision to develop a slow-flying airplane did not in itself solve the problem liaison aircraft. Before an effective combat weapon could be perfected, it was essential to work out the details of its use, especially the organization of which it would become a part, since the nature of the organization would, in a large measure, determine the aircraft’s design. Equipment suited to Air Corps use, operating primarily from bases with maintenance facilities, might well fall short of the equipment required for cow-pasture operation with but the barest of first-echelon maintenance performed by the pilot.

Organic to Ground Forces

Moreover, the question of design was further complicated by the question of operation. The using arms—the Field Artillery, the Cavalry, and the Infantry, as well as the mechanized and armored forces—were convinced that Air Corps observation squadrons could not provide adequate liaison service because they were not integral parts of the ground force team and lacked the ground force point of view. This school of thought held that only by making the liaison units organic parts of the ground force troops which they served could they perform maximum service. This problem of organic versus detached organization was to vex the Air Corps and ground forces for months to come, but of immediate significance to the development of materiel was the fact, that the nature of the organization of liaison units would have an important bearing on the design of the airplanes themselves. Any complications such as adjustable-pitch propellers, intricate flight instruments, etc. implied maintenance and pilot-training problems which almost necessarily required Air Corps organization.

Every month of delay in reaching a decision in the matter of the operation and organization of light aircraft was to cost the Air Corps heavily when the time came for quantity procurement. The go-ahead on light airplanes was officially expressed in a circular proposal (C.P. 39-2) inaugurating a design competition for “short range liaison observation” airplanes, a competition which was scheduled to close on 23 February 1939. This invitation for bids marked a definite step forward, but at the beginning of 1939 actual production on the type stretched out into an indefinite future.

The Materiel Division anticipated a development program in 1940 and 1941 which would produce an improved corps and division observation airplane “based on a compromise” between the requirement for liaison airplanes and the existing corps and army observation type. But the Materiel Division’s plans were only plans. At the time, during the first half of 1939, Air Corps observation squadrons were entirely equipped with corps and division airplanes nearly three years after the decision to divide observation into army reconnaissance, corps and division observation, and corps and division short-range observation.

Something of the confusion of concept which persisted after the introduction of the light airplane type is indicated in the complexity of type terminology in the observation class. Within the compass of the term observation came the reconnaissance airplane, a long-range strategic weapon; the army and corps and division airplane, sometimes called the corps and army airplane; and the short-range liaison airplane. The Materiel Division favored the designation “low speed liaison” to “short-range liaison” because the airplane represented a “distinctly different type as to size, performance, mission and purpose, “but OCAC promised to reach a decision between the two phrases only “when and if the development of the proposed Short Range Liaison airplane” was successfully completed.

Classification of Airplane Types

By the end of 1938 observation aviation as a class included the corps and any single-engine, three-place airplane designated “O”; the corps and division short-range, single-engine, two-place airplane designated “OL”; the corps and division single-engine autogiro or rotary-wing aircraft designated “OG”; the army reconnaissance twin-engine, multiplace airplane designated “R”; and two types of amphibians. If all these designations seemed to cloud the true picture of observation aviation, the time had come when the confusion of terms was to disappear.

In May 1939 a board of officers selected to determine the military characteristics of short-range observation airplanes reaffirmed the earlier three-way division of observation aviation functions: army reconnaissance high-speed, twin-engine, attack-bomber types; corps and division single-engine, armed observation airplanes for “shallow penetration” over hostile areas; and liaison airplanes for command use, liaison, courier, and artillery fire-adjustment missions.

The board’s conclusions, while merely echoing a previously developed philosophy, were important for several reasons. They gave specific definition to the growing concept of segregated observation. Moreover, the board was truly representative, including National Guard, Air Corps, Infantry, and Field Artillery representatives. The board received testimony from those services, as well as reports from the Coast Artillery, GHQ Air Force [bombardment, attack, and pursuit planes], observation squadrons at Forts Knox, Riley, Benning and Sill, and Materiel Division personnel. Most significant of all was the statement of General Arnold, made during the board’s deliberation: “I feel you (the ground forces) should determine more of the character of this vehicle than we because we have to secure the information that you want. We have to please the customer, and you are the customer.”

The attitude typified by General Arnold’s statement was followed by a concrete expression of cooperation in the military characteristics proposed by the board for the short-range liaison airplane, a single-engine, high-wing, two-place, unarmed airplane with a speed range of 40 to 125 m.p.h. capable of clearing 50 feet in a 500-foot run. The plane’s mission was to act as a liaison agent for the use of ground commanders as well as to locate targets and adjust fire for artillery. These military characteristics were not merely academic, for the new short-range liaison airplane designs were just then being evaluated.

First Appropriations

Of 117 bids invited on the circular proposal, 10 were received, and a board of officers selected the designs of Stinson, Bellanca, and Ryan as the winners, in the order named, recommending that three airplanes of each model be obtained. Shortly after the outbreak of war in Europe, the Materiel Division informed the Chief of the Air Corps that three contracts had been negotiated and were awaiting approval:

100Stinson YO-49$1,853,451.69
3Bellanca YO-50181,693.00
3Ryan YO-51132,020.00
Bellanca YO-50
Ryan YO-51 Dragonfly

Contracts approved in September 1939 could not materialize into production in time to meet the demands of the rapidly expanding ground forces. The Field Artillery in particular was insistent upon the need for slow-flying airplanes. Typical of the belated cry for observation-airplane artillery adjustment was an article in the Field Artillery Journal, which declared that there would be no utility in improving the quality and range of field pieces unless Air Corps appropriations included funds earmarked for artillery fire-control airplanes.

The Field Artillery cry was “belated” because in France the ground arms had been pleading for organic artillery-observation aviation over a period of several years. The precedent of World War I in the battles of the Somme and Verdun, “where artillery firing, nearly without exception, was controlled by airplanes,” had made a profound impression on French military thinking. While almost no articles appeared on the subject in the United States, the French military and aviation periodicals were full of discussions regarding organic air units in the artillery and the types of equipment best suited to the work. One writer, discussing artillery aviation, summed up the problem concisely in suggesting that artillery units should be equipped with light, unarmed “tourist” airplanes, such as the Fairchild “24” capable of landing near the battery served.

Fairchild 24, Army UC-61 Forwarder

Probably the most influential French author on the subject in the United States was Lt. Col. A. Verdurand, a French Army air reservist whose discussion of artillery aviation was translated and reprinted at the Army War College for distribution to the services. Colonel Verdurand reviewed the background of aerial artillery observation, cited the dictum of General Estienne prior to 1914 regarding the need tor artillery aviation, and reached the conclusion that artillery aviation should be organic because the air arm would never accord ground cooperation more than a “modest rank in the order of its priorities.” The colonel cited the specific military characteristics which artillery observation aircraft should have: slow speed, no armament, landing qualities suited to operating from unprepared and minute fields near the firing batteries, and demountable wings for road transportation. After suggesting the British Comper Scamp as representative of the desired type, Colonel Verdurand noted that such airplanes should be comparable in cost to a standard five-ton truck.

Scamp Concept by Nicholas Comper. A high-wing monoplane with a pusher engine, a tricycle undercarriage, and a single fin tail-mounted on twin tail-booms.
Comper Scamp Prototype

Without attempting to assess the relative importance or degree of influence exercised by the French publication, it is significant to note that Field Artillery opinion immediately began to reflect a similar attitude. The Chief of Field Artillery was reported as “keenly interested in the development of artillery observation airplanes,” and distressed that “no substantial progress in this highly important matter has been made since the war.”

However thoroughly the higher echelons of command were convinced of the need for slow-flying airplanes, it is important to remember that the tactical units were not yet using them. A Philadelphia National Guard unit borrowed an autogiro for use in the 1939 maneuvers and commented that “even a slow-flying airplane (if we had one) could not approach the autogiro” in being able to find landing fields. If the Air Corps seemed progressive in developing slow-flying airplanes, it must be remembered that the tactical units could not perfect their use without receiving them in quantities.

Re-evaluating Observation

The Office of the Chief of Infantry visualized observation missions in cooperation with infantry troops, including five-mile penetration over hostile areas to locate points of organized defense, massed reserves, tank concentrations, and road blocks, as well as to report promptly to front-line battalions all enemy tactical movements. Despite this extensive function anticipated by the Infantry, the observation squadrons which were to serve the corps and division were still equipped for a very different role.

Early in 1938 the corps area commanders had been instructed to conduct service tests of the [Douglas] O-46 and [North American] O-47 under field service conditions from small, unimproved fields in order to determine whether the substantial increases in speed, weight, and complexity of corps and division observation airplanes had not had an adverse effect upon the suitability of the type to perform its assigned mission.

In response to this directive, the commanding officer of the 97th Observation Squadron reported on maneuvers held at Pine Camp and Fort Dix, where an “excellent opportunity” had been afforded to operate from “small unimproved fields.” The Pine Camp field consisted of two surfaced runways, 100 by 1,000 and 2,000 feet; the Fort Dix field consisted of a sodded square, 1,200 feet to a side. The report considered these areas “typical of what can be expected in wartime use by observation aviation cooperating with the Corps and Division,” and believed that the speeds of the O-46 and O-47 had had “no adverse effect” upon their ability to perform the assigned mission.

Nevertheless, the Materiel Division pointed out that the reports of various boards and studies by the Technical Committee found the O-47 inadequate for corps and division use. OCAC answered: “In view of the proposed Expansion Program of the Air Corps, changes in the Military Characteristics for Corps and Division Observation type airplanes will not be made at this time.” Although OCAC would scarcely admit being committed to a policy of obsolescent airplanes, its unwillingness to re-evaluate existing equipment was almost certain to lead to difficulties in a time when large procurements were anticipated. A report from a tactical unit, received somewhat later, pointed up the nature of these difficulties:

The O-46 is a very nice fair weather cross country airplane for a pilot who is in no great hurry. It is too slow to outrun hostile pursuits and is too heavy to out-maneuver them. It is too heavy to work out of wet, unprepared fields and is too slow on the take-off to get out of fields surrounded by woods, and is too big to hide under the trees.

At almost the very same time this report was written, the Air Corps was purchasing a large number of corps and division airplanes.

Even as late as April 1939, the board evaluating the winners of C.P. 39-2 for utility as to type came to the conclusion that, “justification for the introduction of this type of military airplane has not been sufficiently proven to warrant its procurement in quantity at this time.” Despite this hesitancy, appropriations had been earmarked to provide for 250 short-range type observation airplanes. The following chart gives comprehensive picture of anticipated observation airplane procurement during the critical period immediately prior to the war:

ObservationCorps and Division Liaison
On hand, Dec. 1938246
On order, Dec. 1938113
On hand, Dec. 1939359
On order, Dec. 193974
Supplementary order, 1939
Regular order, 1940
5,500 Program, 1940203250
On hand, 1940411250

The outbreak of war in Europe in September 1939 must have seemed to provide ample justification for pushing the short-range liaison type into production. The O-49 Mockup Board, meeting at Wright Field in September 1939, not only recommended that the government take up its options on the outstanding contract with Stinson but also suggested the utility of considering procurement of stock-mode commercial airplanes, in view of the fact that the requirement for a special type such as the O-49 had resulted in an appreciable increase in cost over commercial airplanes with relatively comparable performance.

The figure of 250 airplanes in the 5,500 Program [launched by the Air Corps in the spring of 1939 guided its expansion for more than a year] had been determined on the basis of three short-range liaison-type airplanes for 41 existing observation squadrons (12 Regular Army and 29 National Guard), or a total of 123 with a 100 per cent reserve of 127, making a total requirement of 250 airplanes. The 100 O-49’s, 3 O-50’s, and 3 O-51’s already on order totaled 106 airplanes, which left 144 of the authorized number as yet, unprovided, but the Air Corps was unwilling to approve additional procurement until extensive service tests could be performed on the new types.

Since the 106 airplanes on order were insufficient to equip existing observation squadrons with a minimum number of airplanes, a total need calculated at 123, there was considerable pressure on the Materiel Division to procure substitutes in the form of commercial models.

The Air Corps had been disappointed in the results of C.P. 39-2, which had returned plans for airplanes costing substantially two-thirds of the cost of existing corps and division types. This unexpectedly high cost had obligated a proportionally great amount of the available funds, making it imperative to consider less expensive models in order to procure the desired quantity without recourse to a deficiency appropriation.

Utilizing Commercial Aircraft Models

Late in November OCAC division chiefs decided to prepare a circular proposal for commercial liaison aircraft to permit a 30-day opening of bids. The objective in mind was to have a sufficient number of airplanes ready for the 1940 spring Army maneuvers. The necessity had become so urgent that the division chiefs agreed to procure commercial models no matter what the utility board findings happened to be.

To implement the policy of reducing the specifications and the requirements in order to make commercial models acceptable, the Air Corps forwarded a revised and amended version of the military characteristics for short-range liaison observation airplanes to The Adjutant General for record and formal approval. The revised form contemplated a mission including “liaison within friendly lines,” primarily to assist corps and division commanders in maintaining contact with brigade, regimental, and battalion headquarters. Most significantly, the performance characteristics, as revised, called for landing and take-off on 1,000-foot sod runways. The Air Corps letter made no secret of the real reason for the changes sought:

In the event an extended service test demonstrates that a strictly commercial type will perform the limited military mission envisioned for this particular type, a savings of approximately $16,000 per airplane can be effected with the added advantage of accelerated production and simplification of procurement in the event of a war.

Furthermore, as the Chief of the Air Corps pointed out, procurement of large numbers of inexpensive, short-range liaison observation airplanes would release the more expensive corps and division observation airplanes from a variety of missions, thereby increasing the number actually available for more extended missions over hostile lines.

When the plan to utilize commercial models was first proposed to the various Army branch chiefs, it was given an “enthusiastic reception,” and their primary question had been to inquire the earliest date at which the light, stock-model airplanes would be available in quantity.

As soon as the revised military characteristics for the type were circulated, however, the enthusiasm turned to criticism. The Chief of Field Artillery summarized the service objections to the amended standards. Fire Control or artillery adjustment had been omitted from the stated mission; the landing and take-off runway distance was objectionably long; and finally, while commercial models were acceptable for test, the Field Artillery was emphatic in pointing out that they were not acceptable as substitutes for the O-49 which had been designed to do a special job and could be expected to do it well.

Acceptable Performance

The objections of the using arms led the Air Corps to rephrase the statement of mission to conform with that prepared for C.P. 39-2, which had produced the O-49. The performance characteristic for landing and take-off was redrafted to conform to O-49 performance as “desired” and to the performance of the best of the commercial models, the Stinson C-105 [Voyager], as the “minimum” acceptable.

Stinson 105 Voyager (HW-75), 1940.

In March 1940, a board or officers appointed to evaluate the bids submitted in response to C.P. 40-550, calling for a 30-day opening, found that all of the airplanes submitted in the competition were of such limited utility that they did not justify procurement. The board recommended all bids be rejected and other steps be taken to fulfill the requirement.

The original requirement for light planes in the 5,500 Program called for 250 airplanes, of which 123 were allocated to squadrons and 127 were reserve. Since 106 had already been procured, only 17 remained to complete the minimum requirement. This number, plus a 15 per cent operating reserve of 18, made a total of 35 airplanes which had to be procured to meet immediate obligations to tactical units. Sufficient funds remained in the 1940 allocation to procure about 35 O-49 airplanes which would meet the minimum requirement, until 1941. This number fell short of the 250 allocated on the 5,500 Program, and the 5,500 Program was to be only the first of an ever-expanding series of programs each more ambitious than its forerunner.

The war in Europe and the Army maneuvers of 1940 were to influence the course of short-range liaison observation airplanes far beyond expectations as tactical experience enlarged the scope of the liaison mission outside the sphere originally conceived for it in military circles.

Chapter VII – Lessons Learned From the European War and From Maneuvers, 1940–1941

Early in 1940 the Air Corps Tactical School circulated a questionnaire among the existing observation squadrons for opinions regarding proposed organizational changes growing from the trend toward mechanization, the formation of the new infantry division, and the development of new observation equipment. The questionnaire was significant not so much for the details it contained as for the attitude it represented. The Tactical School appreciated the changes of the times which impelled reconsideration of tactical doctrine, and directly or indirectly the school’s interest proved important, since shortly thereafter the longstanding basic regulation governing the use of observation aviation, TR 440-15 of October 1935, was superseded by FM 1-5, Employment of Aviation of the Army.

The new field manual considered observation aviation in two classes, reconnaissance on the one hand and observation and liaison on the other. The really radical change over previous doctrine appeared in the definition that observation and liaison aviation were “characterized by the ability to fly at very low speeds and to take off and land within small level areas.” It was apparent from this definition that official thinking was beginning to outstrip existing equipment, for at that time the O-47 and its predecessors were still the standard equipment of observation squadrons.

The growth of the tactical concept of slow-flying airplanes was perhaps far slower in the tactical units, which were still using obsolete equipment, than in the higher echelons of command, where European reports, information concerning anticipated O-49 procurement, and other similar theoretical considerations had been discussed in detail. In reply to a request from OCAC, Plans Division compiled a list of functions tor short-range liaison airplanes to supplement but not supplant the functions assigned to corps and division airplanes.

A New Type of Aircraft

Plans Division envisioned the short-range liaison airplane for use in friendly territory, where security from hostile action would not be solely dependent upon speed of flight and the defensive fire power of the airplane’s own weapons. The new aircraft type was considered suitable for general use as a courier and messenger agent, a convenient transport for unit commanders and staff officers, a command observation airplane suited to use in reconnoitering routes, camp sites, and airdrome locations, as well as a plane to check camouflage and perform conventional infantry and artillery missions of liaison and fire control.

Gradually, the Air Corps and the ground forces were reaching an understanding in the matter of corps and division observation airplanes. As the ground arms drew a clearer picture of the tactical function expected of the air arm, it became increasingly easier for the Air Corps to develop the specialized equipment necessary for the liaison role.

The importance of fostering coordination between air and ground elements was pointedly expressed by a San Antonio Air Depot engineering officer, who considered the O-47 a “very poor job” but confessed to a Materiel Division representative in proposing a slow-flying, short-range observation airplane: “I never realized the need for such an airplane until I took the course at Fort Leavenworth some years ago.” But maneuvers, tactical schools, and command courses, for all their value, could never equal the contribution of actual warfare in the perfection of tactical concepts.

In April 1940 the Military Attaché for Air in Paris, Lt. Col. G.C. Kenney, reported that developments in the European war indicated the urgent necessity of re-examining the existing observation squadron organization and the military characteristics of the equipment used. Unwilling to repeat the failure to accept last-minute reappraisals made at the time of the Expansion Program estimates, OCAC now pointed out that it was exceptionally important to reconsider the problem since the hour had arrived to prepare for the 1942 budget. The Air Corps recommended that a board of representatives from the using arms consider the question at once, but the General Staff saw no need for such a board because the Air Corps Technical Committee was already required by Army Regulations to include using-arm representatives when dealing with questions on cooperation equipment. But whatever the organization of the board or committee, the impact of the reality of war upon military thinking in the United States was unmistakable.

Reports from abroad continued to reiterate the importance of slow-flying observation airplane. The Attaché in London quoted the British War Office as “thoroughly sold on the idea of adopting a light, small, two-place, high wing monoplane for use in close Division observation.” Further reports revealed that British artillery was emphatic in demanding an observation fire-control airplane, since experiences in France and the Low Countries had convinced the army that “dependence upon the RAF, who appear to consider all forms of Army-cooperation a side issue, is futile.” The War Office purchased 200 light Stinsons for artillery and infantry liaison as well as staff-communications missions, and attaché reports revealed that the French air arm was “vitally interested” in a similar development which had been tested in France with success.

The test of combat experience seemed to prove the value of unarmed, slow-flying airplanes, but a fair combat test was difficult, if not impossible, as indicated by the fact that it was War Office funds and not Air Ministry funds which purchased the 200 Stinsons. The contest of organic versus integral air-arm observation units was not an isolated problem peculiar to the United States.

In many respects the Air Corps seemed far more willing than the RAF to cooperate with the ground forces. Unfortunately, the delay in procuring light airplanes in quantity led the ground forces to overemphasize the Air Corps’ unwillingness to cooperate and consequently to stress the necessity of organic observation aviation within the ground arms.

Planes for Every Division

The Field Artillery, in particular, was determined to secure its own air observation posts. Accepting Marshal Foch’s dictum that “there is no combat without artillery and no artillery without aviation,” the Field Artillery quoted reports from the Military Attaché in Germany, where slow-flying airplanes were being used as an “integral part of the combat team” and as “extra eyes for the army, quite apart from the general air arm.” Just why the Field Artillery had not heeded Marshal Foch’s advice 20 years earlier is hard to understand, but whatever the explanation, the fact remained that in July 1940 the Office of the Chief of Field Artillery recommended that a flight of seven light airplanes be assigned to each artillery brigade of the square division.

The Field Artillery proposal for organic observation aviation reflected the failure of the Air Corps to supply the airplanes at the time they were needed and of the kind that were needed. The two characteristics established by the Artillery were (1) airplanes that could land and take off from small unprepared fields, and (2) the immediate availability of such airplanes.

The General Staff did not favor an organic observation aviation element for the Field Artillery on the grounds that to do so would soon lead to a half-dozen separate air elements for all the other arms and services. However, while granting that the existing observation-squadron organization was “admittedly a compromise,” a General Staff spokesman pointed out that there were a number of factors which had prevented observation aviation from developing into an adequate tactical weapon. The lack of maneuvers involving large numbers of troops had hindered the evolution of tactical techniques, while the assignment of observation squadrons to service schools had led to a dangerous overspecialization, such as the development of tow-target work, not related to the primary tactical function.

An Air Corps observation board had previously raised these points in emphasizing the fact that “administrative flying,” in which observation airplanes were used as air base workhorse or utility carriers, had impaired the growth of observation training. Moreover, the board pointed out that until comparatively recently observation squadrons had spent the entire year operating from permanent, home bases with never an opportunity to experience actual field conditions. The board had even gone so far as to suggest that control and responsibility for training observation units might well be vested in the tactical units with which the observation units served rather than in the corps area commanders as current practice had established. This recommendation suggests a definite willingness on the part of the Air Corps to experiment for the best possible solution. The General Staff continued to support the Air Corps’ principle of integrity in frowning on organic observation in the Field Artillery.

Battle Experience

Meanwhile battle experience was influencing Air Corps thinking. When a representative board of Air Corps officers was willing to admit that the O-47 was not satisfactory since the situation in Europe had changed observation tactics and “necessitated radical changes in observation equipment,” the Air Corps was merely reflecting the progress of actual combat conditions of which there had been no successful simulation in the United States for 20 years or more. The response to European reports is nowhere better expressed than in the plans drawn up to overcome the immobility of the existing observation squadron organizations in cooperative action with mechanized forces.

If the Field Artillery demanded organic observation aviation, the Air Corps appeared determined to take every possible step to prevent a similar cry from cropping up among the mechanized division which were expected to grow out of Brig. Gen. A.R. Chaffee’s mechanized brigade. A board of Air Corps officers prepared a revised table of organization for an observation squadron to cooperate with mechanized forces, and the equipment planned for the squadron included two types of aircraft: fast, armed, high-performance, twin-engine airplanes and slow-flying, unarmed, light airplanes for courier-liaison work “well behind friendly lines.”

Despite the fact that the services had been unable to practice with slow-flying airplanes, everywhere the principles of their use were coming to be accepted. The General Staff was reported as being “very much interested” in the problem of light airplanes, and the Chief of the Air Corps had approved a plan to service-test one of each of the three commercial-model airplanes already under procurement at the Fort Benning Infantry School, the Fort Riley Cavalry School, and the Fort Sill Artillery School. Unfortunately, as late as August 1940 the Stinson YO-49 and the Bellanca YO-50 had not yet been completed.

The Materiel Division’s Engineering Section directed the Production Engineering Section to prepare a detailed service-test questionnaire on the technical aspects of the new type, but left the tactical and utility considerations to the using arms. This procedure may have been entirely logical, but the failure to perfect an elaborately detailed tactical questionnaire similar to the technical questionnaire prepared by the Materiel Division had a serious effect upon procurement. Since tactical function was of the utmost importance in basic design, it was dangerous to persist in employing subjective tactical utility reports, or reports of decidedly less objectivity than was customary in Materiel Division technical reports, in the procedure leading toward the development of a new type.

Army Maneuvers Tactical Tests

The acceptance of slow-flying airplanes is perhaps the more remarkable in view of the fact that the demand for the type in quantity preceded the allocation of the initial service-test items. This was, in a measure, the result of European experience, especially that with the German Storch, and partly the result of the shortcomings in existing equipment, such as the O-47, when given adequate tactical tests.

The First Army Maneuvers in Plattsburg in the summer of 1939 demonstrated the “urgent necessity” for an airplane capable of performing liaison missions. The small number of autogiros available was merely sufficient to demonstrate what could be expected of more conventional aircraft with similar characteristics, but the vicious circle was hard to escape. Since there had been, no large-scale maneuvers, it had been difficult to establish a requirement for slow-flying airplanes. With no well-established requirement to justify the expense, it had been difficult for the Materiel Division to develop a unique type of airplane, and now, belatedly, the using arms were demanding a light airplane which the Air Corps had ordered but could not produce in quantity in the short time remaining before the fall maneuvers of 1940.

Admittedly, the 1940 fall maneuvers of the four armies in no case lasted more than five days, but even that limited opportunity for tactical experience in conjunction with a large body of troops promised to be invaluable if it could be exploited. So far as the Air Corps procurement program was concerned, there seemed to be little promise of successful exploitation. But war experience in Europe was to force a decision in observation aviation regardless of the limited scope of the maneuvers of 1940.

Time to Scrap Observation Type

The lessons of combat seemed to demonstrate that the Air Corps had spent 20-odd years backing the wrong airplane. Maj. Gen. D.C. Emmons, reporting first-hand evidence from the scene of action declared in October 1940: “Observation aviation as a type must be scrapped. It cannot function under modem battle conditions. In its place must be a fast, well armed, light bomber.” This report was further amplified by General Emmons on his return from London: “We had the opportunity of talking with several commanders who had served in France prior to the evacuation from Dunkirk; they are definitely of the opinion that the day of the Corps and Division type, as we know it, has gone forever.”

In their haste to abandon the corps and division observation airplane, the British were inclined to discount the value of the light, unarmed, slow-flying airplane, but the Air Corps, while admitting the vulnerability of this type to hostile attack, continued to back the light airplane because of its utility in areas where air superiority made its use possible. The Field Artillery took the occasion to reiterate the need for short-run landing characteristics as an asset in escaping destruction, so that the airplane could land immediately in almost any terrain when threatened by hostile air attacks.

The trend became a policy in October 1940, when the Air Corps Technical Committee made a comprehensive study of observation aviation, with representatives of the Air Corps, GHQ Air Force, Infantry, Field Artillery, Cavalry, Coast, Artillery, and Signal Corps all present to evaluate the experience of the several arms and services in the light of the reports from Europe. The committee’s conclusions were another step in the evolution of the observation concept—in defining the term even more narrowly than before. Observation, the committee decided, would be performed by two types of aircraft: (1) the unarmed, short-range liaison airplane, and (2) the twin-engine, long-range, fully armed airplane for strategic and tactical reconnaissance. The latter possessed military characteristics comparable to those of the light bomber type.

The short-range liaison observation airplane was no longer a service-test stepchild but en equal partner with the twin-engine type. The Technical Committee’s decision did not work an immediate change throughout the service. Official doctrine continued to develop slowly behind the advance of the changing concept.

One Step Backwards

When a new Air Corps Field Manual, FM 1-20, Tactics and Technique of Air Reconnaissance and Observation, appeared in February 1941, it seemed almost that the Technical committee’s decision had been in vain. The new field manual, which continued to discuss corps and division observation airplanes as “light, moderate speed equipment,” asserted that the “most important employment of the balloon” was in artillery observation, and insisted that every staff officer should be a “qualified aerial gunner that he may man the gun of the station he occupies.” The latter was a direct reference to the old corps and division observation airplane.

In the tactical units, however, there was a growing uneasiness about the problem of observation squadrons. An Air Corps officer reported to the commanding general of the IX Army Corps after an inspection trip: “The entire concept of observation aviation… needs to be… remodeled.” After an absence of 10 years, he found “practically no change in the basic theories of the branch and very little change in the equipment assigned.” It appeared that an important branch of the Air Corps had “stagnated for the past fifteen years” and “should be the subject of immediate study.” General Emmons, speaking in an Air Council meeting, was less conservative; he felt that observation aviation had no progressed in 20 years.

The consensus of the Air Council, including Generals Arnold, Drett, and Emmons, Col. M.S. Fairchild, and Assistant Secretary of War for Air Robert A. Lovett, was that observation aviation had fallen into a state of neglect because observation squadrons were isolated from the Air Corps, and corps area commanders certainly could not accept, them as a primary responsibility. In short, the observation squadrons had had no one to “go to bat for them.”

Whatever the cause of the neglected status of observation aviation, by the spring of 1941 even the lower echelons were beginning to realize the inadequacy of the existing organizations. One critic, labeling his remarks the “crystallization of the composite views of many air and ground officers,” probably represented an awareness of observation’s shortcomings that was becoming general when he wrote:

A senior military observer in discussing the German blitzkrieg in France gave as one of the many reasons advanced for the poor performance of the French military forces, the entire lack of aircraft observation for those forces. The French observation was perhaps on a par, plane for plane, with that existing in our army today, and the French observation service was trained along the same lines. If faced with similar conditions, our observation service would be just as helpless, if not more so than the French.

The questioning and critical attitude represented by this statement was probably a healthy one. The evolution of tactical ideas was even less certain than the evolution of technical ideas, for the process of evaluating available information was of necessity infinitely less scientific. Opinion continued to serve in lieu of battle experience. Even where battle experience was available, the process of extracting accurate tactical conclusions reached different ends when different organizations studied the same events.

Doubts Persist

If tactical doctrine evolved slowly in the United States, the same could be said of Great Britain. Air Ministry officials believed that slow-flying, unarmed aircraft would find it difficult to survive under modern battle conditions. The airman’s point of view seemed to persist in distorting the pattern of ground operations: “If you have such a high degree of air superiority that light aircraft can function, then the situation on the ground will not be static; your guns will be constantly on the move, and the demands for air observation will be slight.” Although combat experience in the following three years was to prove this view erroneous, the opinion is worth considering because it helps explain why the Field Artillery demanded organic observation aviation. When an RAF officer, supposedly representing Air Ministry opinion, said of the short-range liaison airplane, “our view on this is, ‘let the soldiers play with their toys, it amuses them and doesn’t do us any harm,'” it is not difficult to understand why there should be differences of opinion regarding tactical doctrine.

The RAF may have scorned light airplanes; British ground forces did not. Observers representing the U.S. Army Field Artillery at British maneuvers in 1941 reported that Stinson and Taylor cubs flown by artillery officers “gave excellent service when used, but unfortunately were forgotten by… commanders after the first day or two.”

Air Observation Post

As in the United States, British experience seemed to demonstrate that there was no substitute for combat in completely “selling” the liaison airplane idea to commanders. Nevertheless, the observers at the British maneuvers drew some important lessons from the British exercises. They were convinced that the “air observation post” was of great value and should be encouraged in the United States; they recognized the necessity of drilling into ground commanders a thorough understanding of the uses of slow-flying airplanes, especially emphasizing the fact that it was very dangerous to misuse an unarmed aircraft. Commanders had to be educated to realize that the slow-flying airplanes could not fly on hostile area missions for which they were not designed.

German commanders were more fortunate. Their “maneuvers” in the invasion of Poland and later in France presented ample opportunity to perfect the use of Storch liaison airplanes in conjunction with ground forces. The Field Artillery Journal reprinted a startling photograph illustrating the Storch at work adjusting artillery fire on a column of French tanks while flying scarcely 200 feet overhead. Artilleristische Rundschau reported in detail on the extensive use of liaison airplanes by the German Army.

Despite all this publicity, word of the new short-range liaison airplane seemed to circulate slowly in the United States. The commanding general of the Fourth Army wrote General Marshall: “I have been informed that the Regular Army squadrons are to get O-49 and O-52 [Curtiss Owl] types this fall… Neither is a modern type and both types have been abandoned by the British and the Germans.” If the general did not know that the O-49 was far from obsolete, he could scarcely be blamed, for the Air Corps had been slow in making good the initial deliveries of the new type.

Early in 1941 the Field Artillery, disgruntled at the slow delivery of the O-49 airplanes, again raised the issue of commercial models to serve as “a suitable stop-gap until the liaison type airplane becomes available in quantity.” An artillery officer writing in the Field Artillery Journal put the question squarely: “Why not use the resources we have?” Admittedly, the Air Corps’ O-49 had superior qualities, but where was it?

Puddle Jumpers

In June 1941 the Secretary of War informed General Arnold of ground force plans to use 12 Piper Cubs during the Second Army’s June maneuvers in Tennessee. The Piper Aircraft Company made the original arrangements with the Second Army, but, believing it wise for the three largest light-airplane manufacturers in the United States to be represented, invited Aeronca and Taylor to participate in the tests. The commercial airplanes employed in this exercise were only rented from the manufacturers and they were flown by civilian pilots who were manufacturers’ representatives.

Apparently the ground forces were enthusiastic, for a similar arrangement was repeated in subsequent maneuvers with the Third Army in July and August, first in Texas and then in Louisiana. When General Arnold learned that airplanes, appropriately called “puddle jumpers” by ground force officers unencumbered with Air Corps terminology, were being procured directly from the manufacturers, he was gravely concerned. The Air Corps was “on the spot” since there were certainly not enough airplanes and pilots to fill the ground force needs. As a Materiel Division officer expressed it: “You can’t blame them for resorting to any measures possible to carry out their required training.”

While the Air Corps disapproved the idea of makeshifts in hiring commercial airplanes, there were obviously very few justifiable arguments against it.” The Materiel Division, however, felt that service tests should be run by service pilots and not by civilian pilots and mechanics, if any accurate indication of utility and maintenance factors were to be obtained. As if oblivious of the entire question of organic observation aviation for the ground forces, the Materiel Division noted: “There is also some agitation for various ground arms to fly their own airplanes.” But if the division really was naive in describing ground force intentions so wildly, there was no lack of realization that service-test reports were absolutely essential. The Engineering Section asked who would submit reports if civilians flew the airplanes, and pointed out that if reports had been prepared on the earlier maneuvers, there was need for them at Wright Field.

General Arnold perceived the danger of lost effort in the civilian enterprise and ordered a 24-hour shift or any other necessary expedient to rush O-49 production at Stinson to the point where it would be possible to equip at least two full squadrons of O-49’s for use in the maneuvers in order to establish an adequate basis of comparison with commercial models.

Simpler, More Affordable, in Greater Quantity

The results of the manufacturer’s trials may have been inadequate from the Material Division’s point of view, but they were sufficient to induce Assistant Secretary of War for Air Lovett to direct General Arnold to procure a service-test quantity of light airplanes from Piper, Aeronca, and Taylor for assignment with Air Force Combat Command. If the commercial models with their known limitations should prove acceptable, production and procurement of light airplanes would be vastly facilitated, since “off-the-shelf” commercial types required on 300 men-hours to manufacture, in contrast to the 6,000 man-hours for the O-49.

In order to secure an over-all picture of the rapidly changing observation-squadron problem, the General Staff circulated a questionnaire to the commanding generals of all armies, corps, and divisions asking information on the experience gained during the maneuver period. The questionnaire sought to determine whether or not observation aviation was always available for artillery action when needed; the number of liaison missions flown; and the time lag between requests for observation aviation and the appearance of airplanes in the area. By these and similar questions, the General Staff hoped to determine the most advisable organization for slow-flying aircraft.

It is impossible to determine exactly how effective the General Staff questionnaire really was, but, in any event the questions asked were probing an important problem, and answers can be found scattered throughout the reports on the maneuvers. General Arnold warned the Chief of Staff that puddle jumpers and O-49’s might serve a useful purpose in peacetime maneuvers, but doubted that they would live very long in actual combat. He feared that the use of light airplanes in maneuvers was likely to create “some strong impression” of what could be expected in war.

Fears of Vulnerability-Casualty

General Arnold’s distrust of the light airplane end fears for the vulnerability of the unarmed type apparently arose from a certain confusion of functions, the same confusion which the observers at British maneuvers warned against. The commanding general of the Air Force Combat Command clarified the issue by describing the difficulty encountered during the Carolina maneuvers, when puddle jumpers on tactical missions beyond the front lines were ruled casualties by the umpires. This experience led him to believe that the trouble lay in the misuse of the term observation or the designation “O” for puddle jumpers functioning as liaison aircraft. The Combat Command suggested the designation “L” for liaison to overcome this tactical difficulty.

This change in nomenclature seemed to settle the issue for the moment, and the services appeared willing to accept the fact that liaison aircraft would function within the periphery of friendly fire. As an artillery man pointed out in the Field Artillery Journal, European experience indicated it to be suicidal to fly below 5,000 feet over hostile areas, and, as a corollary, “that within these altitudes and over our own lines, friendly observation aircraft, would be comparatively safe.”

It remained for a Fort Riley Cavalry officer to express most concisely the prevailing attitude regarding liaison airplanes. They would be very valuable in air areas beyond reach of enemy pursuit, he said. In air areas which could be reached by enemy pursuit, the value of liaison airplanes would be proportional to the degree of air superiority that our forces were able to maintain. Liaison airplanes should not be used for flights over territory occupied by enemy ground forces. Observation end reconnaissance airplanes should be used for such missions.

Visualization of the Liaison Function

This visualization of the liaison function marked an important landmark in the concept of the use of light airplanes. Hitherto, the question of vulnerability had been discussed in positive terms—complete dismissal on the grounds of vulnerability to hostile air action or, at the opposite extreme, a blanket assertion of the need for absolute air supremacy to permit any liaison action. Combat experience was to prove that the Cavalry officer’s opinion was substantially correct. The use of liaison airplanes lay somewhere between complete air supremacy and utter vulnerability. Experience was also to prove that the Cavalry officer’s final dictum on the use of liaison airplanes was note entirely correct, especially when a fluid war of maneuver made the definition of enemy “lines” something unstable.

The maneuvers of 1941 completely sold the light airplane to the ground forces. The Field Artillery, down to the lowest echelon, was enthusiastic. A Mechanized Cavalry officer, speaking for that arm, asserted that the activities of the puddle jumpers with the mechanized regiment produced a “realization among officers and men that such a type of plane is invaluable to ground forces.” The Armored Force was even more specific. Experience of the maneuvers led to the conclusion that the Armored Force would require 15 liaison airplanes for each armored division and six for each armored corps headquarters.

A proposed table of organization forwarded to the Materiel Division to facilitate procurement planning established a tentative requirement for 680 liaison airplanes, including spares:

ProposedTotal OrderFor Liaison Aircraft
Army Observation Group12in medium observation squadrons
48in four armies at 12 each
1220% spares
Total72
Armored Corps6in medium observation squadrons
12in two corps
4spares
Total22
Corps Observation Group6in medium observation squadrons
36in three light observation squadrons
378in nine army corps
99spares
Total519
Cavalry Division6in medium observation squadrons
13in two divisions
4spares
Total22
Armored Division6in medium observation squadrons
36in six divisions
12spares
Total54
==
Grand Total689

The maneuvers were significant because they introduced the liaison airplane to the ground forces, but even more important because of their far-reaching influence on policy. General McNair, Commanding General of the Army Ground Forces, declared that the fall maneuvers, “our first wobbly efforts,” had three definite results so far as air-ground relationships were concerned. First, they paved the way for a new Field Manual, FM 31-35, Aviation Support of Ground Forces, appearing in April 1942, as a revised expression of air-ground doctrine. Second, the maneuvers led to the decision to make artillery observation aviation an organic part of the Field Artillery. And third, the maneuvers induced General McNair to make air-ground cooperation the main item of the 1942 ground force training program.

There could be no further misunderstanding. The Army Ground Forces had adopted the light airplane completely. The AAF faced the obligation of procuring the new-type airplane in sufficient quantity to meet increased demands and of sufficient quality to stand up to the tactical functions forced upon it. Three years or more in active combat were to prove exacting by requiring the light airplane to perform feats undreamed of in the early stages of its use.

Chapter VIII – The Liaison Type is Recognized, 1942–1944

At a puddle-jumper conference in Washington in January 1942, the ground forces established specific requirements for light airplanes. The Field Artillery anticipated a need for 2,750 airplanes. The Infantry repeated an earlier requirement, one squadron of 13 airplanes for every division. Cavalry and Coast Artillery (antiaircraft brigades) requirements brought the total to approximately 4,000 airplanes, a quantity which demonstrated conclusively how thoroughly the ground forces had accepted the light airplane as a tactical instrument.

Acceptance of the puddle jumper did not, however, change the prevailing ground force attitude with reference to the Air Corps. An observer at the conference noted that “the ground officers present were unanimous in their opinion that the Air Corps has throughout the years failed to provide adequate observation aviation of the ground forces.” But circumstances surrounding the procurement of light airplanes in quantity were to prove that the Air Corps was not alone at fault.

Back in August 1941, when the Assistant Secretary of War for Air had directed procurement of a dozen service-test, stock-model airplanes “off-the-shelf” from the three largest light airplane manufacturers, Taylor, Aeronca, and Piper, the Air Corps designated the three makes as YO-57, YO-58, and YO-59 [respectively]. These airplanes, in addition to some others provided independently by the Interstate, Rearwin, and Stinson companies, were not entirely unsatisfactory. The Combat Command reported that they were in some respects “definitely inferior” to the O-49. But the pressing demand for light airplanes could not wait on O-49 production, which had been disturbingly slow.

In November 1941, after the maneuver tests had been completed, the General Staff suggested that despite the superiority of the O-49, the commercial models had sufficient merit, particularly with regard to cost, to make them a suitable substitute. Moreover, commercial-model production promised to offer the least detriment to the program for production of heavier, armed warplanes. Acting on this advice, the Materiel Division began negotiations to procure 617 light airplanes: 342 airplanes divided among the YO-57, YO-58, and YO-59’s, and 275 Stinson “76” [Sentinel] airplanes, a vastly improved model with Stinson had hurried to completion during the fall maneuvers.

When the Washington puddle jumper conference established an over-all requirement for 4,000 light airplanes, the Chief of the AAF directed the Materiel Division to increase the existing procurement by 1,000 airplanes. Six months later this number was increased by 1,960 airplanes, entirely for allocation to the Field Artillery.

Observation Changed to Liaison

The light airplane had become a mass-production article. In April 1942 the Secretary of War ordered the designation Observation changed to Liaison. The O-49 became the L-1 and the O-57, O-58, and O-59 became the L-2, L-3, and L-4 respectively. But the liaison aircraft did not really come of age until October, when the Director of Military Requirements issued a statement of liaison aircraft military characteristics which effectively established the type as a class of its own.

The appearance of liaison aircraft as a distinct type, however, did not solve the problems which were inherent in the peculiar position of a weapon procured by the Army Air Forces for use with the Army Ground Forces. One of the most serious difficulties of this dual position grew from the problem of establishing a detailed requirement for the military characteristics desired. The Air Corps’ failure to deliver a slow-flying airplane in the numbers asked by the ground forces had led the latter to resort to less satisfactory commercial models which were already in production. Because these commercial models were procured irregularly, at first on a rental basis end later in a limited, service-test quantity, the normal channels of service-test procedure were destroyed. This difficulty was further involved by the fact that the using agencies represented a number of different activities.

The tactical role conceived by the Infantry for liaison airplanes differed in many respects from that envisioned by the Armored Force. With no standardized service-test procedure established to define the desired characteristics of tactical utility, and with different tactical objectives to strive for, it is not surprising that the liaison airplane program developed in confusion.

When the Washington conference indicated that liaison airplanes would become big business, the Secretary of War pointed out that there were some 50 manufacturers of light airplanes in the United states with extensive productive capacity, but to avoid complexities of supply and maintenance, he urged that every effort be made to concentrate on a single design and type. Despite this logical recommendation, it seemed impossible to single out a design for standardization, and service tests continued to be somewhat haphazard. The 12th Observation Squadron at Fort Knox reported that the Interstate Cadet, available for testing in the North Carolina maneuvers, had been “much more satisfactory” than either the Taylor or Piper Cubs. The Fort Knox report was enthusiastic: “All pilots who flew this ship found it highly superior to any other ship of its class.” On the basis of this evidence, the Experimental Engineering Section at Wright Field requested permission to procure a service-test quantity.

Instructions from the Materiel Division headquarters in Washington disapproved the service-test plan and ordered a single Interstate to be tested at Wright Field by an “informal board,” including representatives of the Armored Force and the Air Support Command. If the results, of this test proved satisfactory, the board was to submit a recommendation for a production rather than a service-test quantity. The Experimental Engineering Section cautiously replied that a “very informal board” had approved the Interstate L-6 (sometimes called O-63) but wished to compare it with the Stinson “76” or L-5 ( sometimes called O-62) in service-test quantity before putting it into production.

Rush to Fill Demand

This instance was one isolated case of many during the period of procuring and evaluating commercial models of liaison airplanes, but it is representative of the irregular and abnormal situation which prevailed during the rush to fill the sudden demand for liaison aircraft made by the ground forces. Nevertheless, even in view of the fact that the liaison airplane program was only a small portion of the Materiel Division’s procurement problems at the moment, the Experimental Engineering Section prepared specifications for an entirely new liaison airplane, a pusher type with emphasis on improved vision. The specifications were circulated to six light-airplane manufacturers, three of whom carried on advanced design studies.

The Materiel Division eventually decided not to enter into any contracts for the new type, but the foray in the field on unconventional design demonstrated the division’s attitude with regard to continuing development along experimental lines. Unfortunately, the rapidly expanding requirement for liaison airplanes made production appear more important than improved design, and the division had to concentrate on turning out relatively inferior and unsatisfactory airplanes in quantity rather than press the development for a superior design.

The demand for liaison airplanes grew even beyond military circles, Lend-Lease requirements, including requests from South American governments, made it evident that the light-airplane manufacturers were going to encounter an enormously increased production program. In November 1942 civilian and military agencies, whose activities required the use of light airplanes, held a meeting in Washington to coordinate 1943 requirements.

The Civil Air Patrol, engaged in 600,000 miles of coastal patrol each week and 40,000 miles of courier service each day, indicated a need for 200 airplanes in the L-2 class (which included L-2, L-3, and L-4), in addition to other, larger types. The Civilian Pilot Training Program, engaged in training flight instructors, liaison pilots, ferry pilots, and glider pilots, declared a requirement for 1,220 airplanes in the L-2 class in addition to other non-liaison types. The Office of the Coordinator of Inter-American Affairs anticipated a requirement for 100 airplanes of the L-2 class for Latin America, and the Army Ground Forces increased their requirement by 2,500.

The AAF air-ground support program would be satisfied by Stinson L-5 and Interstate L-6 production, but AAF Base Services expected to require 1,511 airplanes of the L-2 class. Secret operations planned by the Office of Strategic Services—presumably activities in conjunction with the underground in enemy-occupied countries—raised the L-2 class requirement by 1,700 airplanes to a total of 7,231, not including the estimated 5,000 airplanes in the non-liaison category.

On the basis of this conference, the Joint Aircraft Committee recommended that approximately 3,000 airplanes of the L-2, L-3, and L-4 types be procured by the AAF from existing facilities. The Committee recommended against procurement of the 9,000-odd additional airplanes “in view of the great shortage of machine tools, materials, and labor for the existing aircraft program.”

More Exacting Requirements

When there were no liaison airplanes at all, the ground forces had been enthusiastic about the “off-the-shelf” commercial models which the Assistant Secretary for War for Air had directed the Air Corps to procure; but when the commercial models were compared with superior types, the ground forces became more exacting in their requirements. Throughout 1943, repeated operational accidents at Fort Sill led the Field Artillery to ground all L-2 and L-3 airplanes and request the Air Corps to replace these types with L-4’s, the military equivalent of the commercial Piper.

The Field Artillery believed that the L-4, a 65-hp. airplane, was the “ultimate in simplicity” and ideally suited to artillery use. True, its take-off characteristics could be improved, but its maintenance was sufficiently simple for it to be accepted as ideal for Field Artillery operating conditions. The Air Corps, however, favored the L-5, a 185-hp. Stinson, twice as heavy as the L-4, though equipped with slots and flaps which gave it performance characteristics superior to those of the L-4. But the Field Artillery believed that these refinements were attained at the cost of increased complication in operation and maintenance. The Field Artillery considered the L-5 far too difficult to keep in repair under field conditions with “primitive equipment” and much “too hot” in the air for Field Artillery pilots.

The difference of opinion between the Air Corps and the Field Artillery regarding the relative merits of the L-4 and L-5 represented the very crux of the organic observation problem. The Field Artillery wanted organic aviation elements because there seemed to be no other way to secure air observation with an Artillery point of view. But organic artillery aviation required relatively simple airplanes, easy to fly and easy to maintain. Simple airplanes could not produce the desired military characteristics, especially with regard to short take-off and landing runs.

When the Air Corps procured airplanes with superior characteristics, their complexity inevitably increased, and they became more difficult to fly and more difficult to maintain on the ground. Since production capacity had very definite limitations, it was both logical and economical for the Air Corps to want to limit production to a single type. And because all the using agencies, save the Field Artillery with organic aviation elements, were interested in superior performance rather than simplicity of design, the Air Corps had every reason to favor the L-5 over the L-4. The Field Artillery problem, however, could not be dismissed entirely and a compromise was natural.

In line with over-all AAF policy, the AAF Board recommended, in October 1943, that action be taken to reduce the number of airplane types being manufactured. Consequently, the OC&R Requirements Division, while preparing 1944 estimates for the liaison airplane program, undertook to review the entire liaison airplane series.

Consolidation, Production Standard

By the end of December 1943 there were approximately 178 L-1 (O-49) airplanes in the AAF. Although the characteristics of the L-1 type more nearly fulfilled the requirement for a liaison airplane than any other fixed-wing aircraft produced up to that time, considerations of cost, production, size, weight, and maintenance made the L-1 undesirable as a standard type. The Army Air Forces and the Army Ground Forces together had 1,496 L-2 airplanes, 1,055 L-3 airplanes, and 2,079 L-4 airplanes. Since no further requirement existed for the L-2 and L-3, those types were recommended for classification as limited standard, while the L-4 retained the classification of standard for the Army Ground Forces.

There were 900 L-5 airplanes in the AAF at the end of 1943. Since this type was especially designed as a liaison airplane, it approached the L-1 in performance and characteristics without the attendant problems of cost, maintenance, etc. The L-5 was recommended for classification as standard for the AAF, but the L-6, of which there were 208 at the year’s end, failed to live up to the expectations, and, falling short of the L-5 in performance, was recommended for classification as obsolete.

There was considerable pressure in 1944 on the Director of Military Requirements to expand enormously the production of liaison airplanes. The director wrote, in December 1943:

It is not known in this office from whence came the requirement for 12,000 airplanes which has been sent to the Joint Aircraft Committee. It is presumed, however, that it originated in the Office of Strategic Services, an organization sponsored, so far as this office can learn, by a non-military high pressure group of light plane manufacturers and private operators with strong political connections.

At any rate, the anticipated expansion did not alter the AAF estimates for 1,200 L-4 and 1,200 L-5 airplanes. Not counting 306 airplanes on L-2 and L-3 contracts from the previous year, liaison airplane deliveries for 1944 actually reached 3,265, including 1,904 L-4 airplanes and 1,361 L-5 airplanes.

Throughout 1944 the pattern of liaison airplane development continued to reflect the basic problems which had been apparent in the preceding 20-odd years. The Army Ground Forces suggested further airplane development; the Army Air Forces retorted that the introduction of new models would lead to production difficulties and increased complexities in the supply of spare parts. Moreover, the Materiel Command had introduced a series of improvements which made the L-4 more rugged than ever before. But improvements were made at the cost of performance. Increased weight increased the length of the take-off and landing run of the L-4, and this above all was the airplane’s vital quality if it was to continue operating successfully in the mediate vicinity of command posts and battery positions from unprepared, cow-pasture fields.

The AAF answer to the the faltering performance of the L-4 with its accretions and modifications was to suggest the L-5 with higher horsepower engines and controllable-pitch propellers. This proposal, which was at variance with the Field Artillery requirement for a low-cost airplane, easy to fly and easy to maintain with primitive equipment in the field, probably helps to explain certain objections raised by the Army Ground Forces to FM 100-20, Command Employment of Air Power.

Reminiscing the L-1 Vigilant

The Materiel Command may have felt in some sense well pleased in July 1944 when General Eisenhower in the European theater sent a personal wire to General Arnold asking for British Whizzers. The Whizzer was the Stinson Vigilant, an airplane very similar to the German Storch, which he declared “absolutely essential” for corps and division commanders. Since the Vigilant was substantially the same airplane as the O-49 or L-1, which the Materiel Command had originally procured for the very purpose General Eisenhower had in mind, the Materiel Command might have been inclined to consider the job well done. On the other hand, General Eisenhower, in referring to the British Whizzer rather than to the equivalent L-1, may have implied that the AAF failed to provide the airplane which the ground forces wanted.

When General Eisenhower’s request reached Washington, the L-1 was already long out of production and branded “obsolete.” Despite the general’s specific objections to the L-4 and L-5 as too slow at take-off and unable to descend fast enough for reasonable safety when attacked by hostile intruders, the AAF intended to improve the L-5 with a controllable-pitch propeller, giving it characteristics comparable to the L-1. Clearly, there could be no definitive solution to the problem of AGF requirement and AAF development, but systematizing and formalizing the means of determining tactically useful performance characteristics would go along way toward simplifying the procurement of airplanes attaining the desired objectives.

While the Requirements Division hoped to approach L-1 performance by using an L-5 with controllable-pitch propeller, request from the India-Burma sector pressed for the L-1 or the L-5, with as many of the former’s characteristics as possible, to use in removing litter patients from restricted jungle areas and dropping supplies from bomb shackle mounts to isolated garrisons.

From the same area came reports of helicopters operating 150 miles deep in enemy territory, rescuing pilot casualties in areas where Japanese patrols and air surveillance made it impossible to prepare even small strips for conventional liaisons. The evidence is hard to ignore. The peacetime argument that the vulnerability of unarmed, light airplanes would make their use impossible was proved absolutely wrong. Combat experience, as summarized in an AAF Regulation on liaison aircraft in November 1944, had demonstrated the fallibility of dogmatic assertions on the worth of light airplanes. Artillery adjustment, reconnaissance and light photographic observation, troop and light-cargo transport, aerial evacuation, column control on the march, camouflage checking and wire laying for communications—these and a dozen other command, liaison, utility, and courier functions, “consistent with the limitations of liaison aircraft,” were designated as the mission of the unarmed airplane.

The fears of those who argued the excessive vulnerability of the unarmed liaison airplane were probably demolished more effectively by the following Associated Press news item of April 1943 than by any other means:

West Front Tales

With the U.S. Seventh Army – (AP) – The Third Infantry Division with its proud record of 22 Congressional Medals of Honor regards itself as one of the Toughest outfits in any army… In a recent battle, “Iron Mike” O’Daniel (Maj. Gen. John W. O’Daniel, the division commander) watched from a cub plane while a company took one position but hesitated to move forward without reconnaissance. The General’s plane swooped low. He dropped a note saying, “No Boche [slang for German soldier] for two kilometers. Get moving.” The company moved.

Reconnaissance in the L-4, Piper Cub.

Summary

The evolution of the liaison airplane is of peculiar interest to the Army Air Forces because the type represents a cross section of problems involving both air and ground arm functions. From the summary of the liaison airplane in evolution, it is possible to extract some valuable lessons in the form of tentative conclusions.

The development of military airplanes during the 1920’s was hampered by the paucity of tactical studies based on World War I experience. Those accounts of aerial combat which were available were found to contain a disproportionate element of subjective opinion.

Not only were the analytical studies on airplane tactics few and therefore of limited utility at the end of World War I, but the machinery for evaluating those studies, the organization for converting tactical requirements into engineering facts, was never perfected. The remarkable system which had been organized at McCook Field during that war fell apart in a matter of weeks after the Armistice.

The heritage of World War I was unfortunate in that it seemed to stress airplanes rather than principles. The engineers who were confronted with the task of designing airplanes for observation were advised to build two- or three-place biplanes with fixed forward guns and flexible rear-firing guns. In short, the engineers inherited airplanes to improve rather than objectives to strive for. They were given a tradition, a complex of opinions and prejudices, as well as a body of experience. They were not given a series of tactical functions around which to build the best airplane possible.

The danger in attempting to develop an airplane, that is, perfecting a trend rather than building directly toward the most adequate solution of the tactical functions desired, was especially significant in the case of the liaison airplane. World War I presented, a highly specialized tactical situation. Throughout the greater part of the war the opposing sides operated from behind relatively stabilized lines from prepared airdromes. The airplane that was developed for observation and liaison purposes was the answer to that specific situation; it was a highly specialized instrument designed for a specific role.

The mistake of the Air Corps lay in the failure to identity the observation airplane of 1918 as a specialized weapon. The most convincing proof of this mistake appeared in 1940, when, after the first few months of warfare in Europe, the corps and division airplane disappeared. The Air Corp had backed the wrong horse for 20 years. There may be some consolation in the fact that other nations had made the same error.

Another lesson inherent in the evolution of liaison airplanes seems to point to the importance of large-scale maneuvers under field conditions. Undoubtedly a large measure of the failure to develop corps and division observation airplanes to meet the ultimate tactical role lay in the fact that, maneuvers, limited as they were down to 1940, were utterly lacking in realism. Observation squadrons supporting “opposing” armies from the same airdrome probably represent the apogee of absurdity, but even the best efforts of the Air Corps would probably be destined to fill until the opposing armies represented at least corps-sized groups or ground troops.

Inadequate and unrealistic air-ground maneuvers delayed the development of corps and division airplanes. This delay induced the Field Artillery to ask for organic aviation, which in turn forced the Air Corps to interrupt its normal technical development and improvement to continue production on airplanes simple enough for ground-arm operation. Without maneuvers, the air and ground arms could not grow together normally throughout the years, and inevitably the sudden expansion induced by the war emergency brought acute growing pains, organizational problems, and design difficulties.

The Air Corps probably unconsciously neglected to theorize on its tactical role in struggling to obtain recognition for the potential strategic role of aviation, but even if the emphasis of interest was placed on strategic weapons, the sizable number of “observation” airplanes produced in the between-war years certainly indicates that the tactical role was not slighted. There were many more observation airplanes than bombers down to the outbreak of World War II.

The case of the liaison aircraft suggests the utility of theorizing on the objectives desired when establishing military characteristics tor a new-type airplane. The handbooks on observation aviation prepared at the Tactical school went on year after year reprinting the same old truisms, which apparently did not even reflect more than a very limited survey of the available tactical studies from World War I. Tactical School theory influenced the boards and individuals who were responsible for establishing the performance characteristics desired, and lack of theorizing led to stagnation in design.

The extent to which this stagnation could be carried is interestingly illustrated by the case of the slow-flying airplane. The United States perfected a slow airplane in the Guggenheim Safe Plane competition, but the failure to speculate on its potential military use left the development of liaison aircraft to continue on its traditional course until the German Storch appeared to make its profound impression.

The dangers inherent in a relatively unquestioning acceptance of existing doctrine are clearly apparent in the contradictions found in the discussion of liaison airplanes on the one hand and observation-balloon policy on the other. While the Air Corps continued to accept the ungainly and helpless kite balloon with its obvious exposure to enemy action, it raised the most serious objections to the unarmed, light airplane because of its complete vulnerability. Inconsistencies of this sort seem to indicate a failure to carry the theoretical approach, in preparing military characteristics for a type, to a logical conclusion.

The importance of clear reasoning and thoroughly systematic approach to the problem of compiling type characteristics is illustrated by the reports of military attachés in foreign capitals. As individuals, military attachés are bound to suffer from the same subjective limitations which hinder those who write tactical résumés, but taken collectively, the information gathered by the attachés probably represents a most vital source of information. German development of the Storch was extremely influential in altering the Air Corps trend of design and tactical concept. The several attachés, as well as the NACA European technical assistant who reported on the Storch, secured sufficient information about the new airplane and its use to lead to the conclusions which were ultimately reached in the United States, but the evidence suggests that the individuals primarily concerned with military-type characteristics made comparatively little immediate use of the attaché and NACA reports.

The entire development program of liaison airplanes, dealing as it does with an exceptionally difficult problem of coordinating functional requirements with the ground ams, revealed one conclusion above any others. If the tactical objectives, the functions which an airplane is going to be called upon to perform, are hazy, the engineering objectives will be obscure. Unless the tactical objectives are clearly defined and accessible to those who compile type characteristics, there can be no adequate objectives for design, for technical and engineering advance. If the AAF is to avoid repeating the mistake of the corps and division observation airplane, it would do well to perfect the system of evolving military characteristics for types and to rationalize the method of obtaining tactical-performance data both at the service-test and combat level until tactical characteristics can be expressed almost as accurately and as definitively as technical characteristics.

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