TIMELINE
1934 - 1940
History From 1934-1940

Summary
The mid to late 1930s saw the first helicopters capable of meeting the parameters of what might be termed a “successful” helicopter – i.e. capable of control about all axes, capable of translational flight, capable of autorotation, capable of flight out of ground effect and capable of flight to the endurance of its fuel. Whether these machines might be considered “practical” is another matter as they were severely lacking in payload, and could often be less stable than desired. The most significant advances occurred in Germany and France, with other important advances occurring in Great Britain. The promising advances of the Soviet Union suffered heavily under the heavy hand of Stalin’s purges. Outside of the small and ailing Autogiro industry, the United States remained a backwater of rotary wing development, but by 1939, the situation had begun to change as enterprising engineers and designers such as Igor Sikorsky and Arthur Young turned their attention to “the helicopter problem”.

Technology
The greatest advances occurred amongst those pioneers with experience in gyroplanes. Henrich Focke and Anton Flettner realized helicopter development as a continuum between their work with autorotating wings and their ultimate success in helicopter design. In 1935, famed French designer Louis Breguét and his engineer René Dorand achieved a significant milestone with their coaxial Gyroplane (which was not a gyroplane at all, but a true helicopter), which generally outperformed all previous helicopters by a wide margin (though it did not demonstrate an entirely “successful” autorotation). The design was particularly notable for full cyclic (lateral and longitudinal) and collective control. Outside of this advance, it was otherwise a fairly cumbersome and ungainly machine. Focke’s 1936 Fw 61 was less advanced in terms of control, featuring only longitudinal cyclic control in a cumbersome mechanism, but it was otherwise more refined and outperformed Breguét’s design by a wide margin.

The Autogiro industry was beginning its terminal descent, but military contracts kept it alive in the United States and Europe long enough for it to make additional contributions. The hybrid airplane wings and controls of first generation Autogiros disappeared in favor of “direct control” which greatly enhanced low-speed handling and stability. However, as Autogiros became more dependent on their rotors they became increasingly vulnerable to the condition of ground resonance, which would absorb a disproportionate amount of research and development funds. Jump takeoff was the hope for the future, but this line of development was insufficient to stop the shift away from Autogiros and towards helicopters and other alternatives (e.g. “grasshopper” STOL lightplanes, such as the Fieseler Storch). The most notable advances occurred at Raoul Hafner, an Austrian working in Britain, who started dabbling in gyroplanes with the intent of using them as a bridge to the practical helicopter. His innovative “spider” method of full cyclic and collective control was a remarkable advance ready-made for helicopters, but unfortunately conservatism in the Autogiro industry prevented its wider dissemination until the late 1940s when it was adopted on Britain’s first indigenous production helicopter, the Bristol 171.

Application and Operations
The struggle with technological and doctrinal changes in the nature of warfare during the interwar period led the military to become the primary adopter of rotary wing technology. Britain, France and Russia made significant efforts to develop operational battlefield gyroplanes, but it was the increasing militarization of Germany and its hospitable orientation towards new innovations with potential military applications that gave the helicopter its biggest boost towards becoming a viable operational aircraft. By 1939, prominent advocates in the Reichsluftfahrtministerium (RLM – Air Ministry), such as Ernst Üdet, had given Focke’s helicopter a prominent place in the Third Reich’s propaganda campaign and supported further development in spite of his tenuous Nazi credentials. The prominent place of the Fw 61 in Germany would ironically be used by American helicopter to garner their own funds to develop military helicopters. Meanwhile, Anton Flettner’s Fl 265 found some potential favor with the German Kriegsmarine as a potential submarine spotting platform.

The United States saw the Army Air Corps finally acknowledging the Autogiros after the Army Ground Forces had forced their hand with a Presidential directive from Franklin Roosevelt in 1934. The Air Corps saw the low and slow nature of the Autogiro as counterintuitive to its move towards ever-more high performance observation aircraft. However, the Ground Forces were looking for a more flexible observation platform than the tethered kite balloon and the Autogiro seemed to hold some promise in this regard. Not until World War II were the semantics of this debate resolved, with “Observation” disappearing in favor of “Reconnaissance” and “Liaison” (though not without considerable animosity between the two branches of the Army). Succumbing to pressure, the Air Corps began testing Autogiros, with the predominant type being Kellett’s YG-1. These Autogiros introduced the American Army to rotary wing aircraft on the eve of war, and if not a success in their trials, they did give hope that future developments might make rotary wing aircraft a worthwhile presence on the battlefield. Even this hope seemed to fade in the fall of 1938 when Wright Field saw a Fieseler Storch fly off against a Kellett YG-1. The Kellett slightly outperformed the Storch in takeoff and landing distance, but was sorely lacking in terms of payload, operating costs and maintainability.

In the civil sector, limited commercial use of Autogiros continued with some hope being held out for the Autogiro in urban mail service, but without heavy subsidies, such efforts had no hope of success in competition with more economical and conventional forms of transport.

Design and Manufacture
Focke ushered in the quantity manufacturing of helicopters (but not mass production) with the Fw 61 of which he built two. Though built at the Focke-Wulf plant, Focke’s relationship with that firm had deteriorated as it became increasingly politicized with the Nazis, so the helicopter marked Focke’s effort to strike out on his own. Flettner’s six Fl 265s were still short of mass production, but the move towards war was increasing the inertia of helicopter manufacturers. In the United States, by late 1938, Igor Sikorsky who had visited Germany and seen the Fw 61 in action, found his United Aircraft owned factory idle as he lost major flying boat contracts to Boeing and Martin. He successfully convinced his superiors at United to roll the aircraft on an experimental helicopter contract. The first large American aircraft manufacturer had now become involved in helicopter development with the Vought-Sikorsky VS-300.

Autogiro manufacturers saw small sustenance orders and generally the recovery phase of the Depression was harder on the industry than the darkest days had been. Companies like Kellett often had to turn to supplemental forms of income such as the manufacture of surgical lamps. Orders were typically in the single digits and the total production runs for Autogiro concerns in this period was measured in the tens, not hundreds of aircraft.

Government Involvement
Though the United States clearly lagged behind several European nations in the integration of Autogiros into the military reconnaissance role and the promotion of the helicopter as propaganda in Germany, 1938 saw a significant change in the role of American government in Autogiro development. The so-called Dorsey Bill designed by its sponsoring Pennsylvanian Congressman, Frank Dorsey, to aid the critically ailing Autogiro industry (then based exclusively in that state), instead resulted in the creation of dedicated board administered by the Army Air Corps to oversee rotary wing development, not only for its own interests, but also those of other interested government agencies. Though the intended $2M appropriation emerged as a fairly paltry $300,000, it coincided with some opportunistic alarms put forth by Laurence LePage, who in failing to achieve a license from Focke, elected to create anxiety that would support his own competing design. Beating out fellow competitor Sikorsky and the Autogiro manufacturers Pitcairn and Kellett, LePage and engineer Havilland Platt received the first government contract in the United States for a helicopter – the XR-1. Thus, even though the STOL plane had effectively eliminated future operational prospects for the Autogiro, enough inertia had built up behind the helicopter that it received critical support at time when military necessity was on the verge of rendering debates about the potential utility of the helicopter academic.

Representative Designs
Kellett YG-1B
Autogiro Company of America AC-35
Cierva C.30
Breguét-Dorand Gyroplane
Focke Fw 61
Flettner Fl 265
Hafner A.R. III

Notable Personalities
J.A.J. Bennett
Agnew Larsen
Richard Prewitt
Raoul Hafner
René Dorand
Henrich Focke
Anton Flettner
H. F. Gregory