Design and Development History of the Canadair Cl-84 V/Stol Tilt-Wing Aircraft
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DESIGN AND DEVELOPMENT HISTORY OF THE CANADAIR CL-84 V/STOL TILT-WING AIRCRAFT Introduction Throughout time man raised his head to the heavens while watching the seemingly effortless flight of birds and insects, and dreamed of achieving the full range of flight: to rise upwards, soar, hover and land safely on fixed wings. At the dawn of the 20th century twelve seconds that changed the world occurred with the first powered flight of a fixed wing airplane, and man began to achieve much of his dream. Some preferred the prospect of using rotary wings to explore the skies, exploiting a unique ability that fixed wing aircraft could not attain, with Leonardo da Vinci having the forethought of producing the first conceptual drawings of a helicopter more than 400 years ago. Engine manufacturers were soon working hand in hand with the early aircraft manufacturers in an effort to appease both schools of thought regarding how best to accomplish powered flight reliably and economically in all regimes. The development of high power-to-weight ratio gas turbine engines made possible the design of a new family of convertiplane aircraft combining the speed, range and efficiency of the fixed-wing airplane, with the vertical take-off and landing, and slow-flight capabilities of the helicopter. Canadair Limited in Montreal, Quebec, was formerly the Aircraft Division of Canadian Vickers Limited from the early 1920s until the Aircraft Division was officially reorganized by the Canadian Government as a Crown-owned corporation on 3 October 1944. Due to space constraints at Vickers, this Division was relocated to the nearby Cartierville Airport, the oldest airfield in Canada. Canadair Limited was sold to the Electric Boat Company of Groton, Connecticut, in January 1947. Electric Boat also owned Convair, the acronym for the merged Consolidated Aircraft and Vultee Aircraft Corporations. These organizations formed the nucleus of what was to eventually be known as the General Dynamics Corporation in 1952. Canadair, the largest manufacturer of aircraft in Canada, was the Canadian subsidiary and paragon of the General Dynamics Corporation from February 1947 until the Canadian Government bought it back as a Government-owned concern on 5 January 1976. The General Dynamics Corporation, through its Canadair and Convair Divisions, was actively interested in the idea of Vertical Take Off and Landing (VTOL) aircraft since the advent of the gas turbine engine expanded the possibilities of VTOL aircraft beyond the helicopter concept. Convair made an advanced and outstanding contribution in the field of VTOL flight in the early 1950s when the XFY-1 Pogo tail-sitter, the world’s first successful fixed wing vertical take-off aircraft, was manufactured and flight-tested as a proposed convoy escort fighter for the US Navy. Since that time, continuous theoretical and experimental studies by both Canadair and Convair significantly advanced the state-of-the art in VTOL aircraft that eventually resulted in various specific aircraft proposals. What follows is the background and complete history on Canadair’s Vertical/Short Takeoff and Landing (V/STOL) aircraft research and development programmes. This chronology covers from the early design of proposed V/STOL concepts and test models, through to the highly successful Canadian Armed Forces CL-84-1 tilt-wing/slipstream deflection V/STOL evaluation aircraft, and concludes with the final legacy of Canadair VTOL design and development – the CL-227 series of Remotely Piloted Vehicles (RPVs). Cover Photo Caption: Canadair’s CL-84-1, CAF serial CX8402 literally flies circles around low-hovering sister ship, CX8401 in November 1972. ACKNOWLEDGEMENTS For all those aviation enthusiasts who are, or were, fascinated and interested in the varied experimental, prototype, developmental, the one-off or just plain weird aircraft produced by foreign aviation manufacturers and test organizations around the world, here is the history of a fascinating and interesting Canadian-designed and built aircraft. The limited number of such research and development aircraft types is rarely recognized fully in print with corresponding little known or seen associated photographs compared to the oft-repeated tomes written about their over hyped production brethren. At the Canadair Limited 50th Anniversary special event in June 1984, renown Canadian aviation author and historian Larry Milberry challenged and inspired me to; “…write it ALL down to preserve the history”, of the aircraft and projects that have only had scant and abbreviated mention in the print media. As an honour to the imaginative designers, engineers and technologists, as well as the manufacturing, assembly and test personnel, and, of course, the brave and dedicated flight test crews, this is written to preserve the full history of the limited production of the truly unique Canadair CL-84 V/STOL tilt-wing aircraft. Many thanks go to the following that helped to make this full historical rendition possible: Doug Adkins, Catherine Chase, Bob Deans, Garth Dingman, Roy Dishlevoy, Ken Dommett, Marc Ducharme, John Hillsdon, LCol Barry Gartner and Mrs. Laura Gartner, Brian Griffith, Peter Hargrove, Maurice Holloway, Larry Milberry, V.R. (Butch) Miller, Tim Leslie and Margaret (Marg) Bower of the NRC at Uplands, George Parker, Brian Parrack, Ron Pickler, Robert St-Pierre, Dick Richmond, John Robinson, Mark Roe, Paul Sagala, Wayne Saunders, Fred Shortt, Cliff Symons, Gord Tottle, Marc-André Valiquette, and Larry Zbitnew. And, my parents, who continually berated me over many, many years as to what the hell was I going to do with all this “airplane stuff” that I had amassed and was now collecting dust. – Well, as a short answer, on the following pages is a very small part of that mass of dust-collecting history. All photographs and drawings were provided courtesy Canadair Limited and Bombardier Aerospace via the author’s collection unless otherwise indicated. Bill Upton Blainville, Quebec, Canada 2013 Early Deflected Slipstream and Tilt Wing V/STOL Research During the tense Cold War era of the 1950s and 1960s, the study, research and development of varied types of V/STOL aircraft configurations was deemed imperative to the successful operations of military air forces, particularly those in North America. With the probability that a first strike attack could be against civilian and military aerodromes, to deter or prevent retaliatory offensive and hinder counteractive defensive capabilities, the need to somehow get aircraft airborne from short strips, roads, and unprepared areas was paramount towards gaining air superiority and ensuring survival. In early 1950, the United States Army and the United States Air Force (USAF) began joint engineering and design studies towards determining the general characteristics of a convertiplane concept that could rise and descend vertically like a helicopter and fly horizontally with the speed of a conventional aircraft. Initial studies tended towards a single seat, deflected slipstream / tilt wing configuration that could be capable of a forward speed of 260 knots (483 km/h / 300 mph), be able to hover at 1,524 m (5,000 ft), and have a service ceiling of 4,877 m (16,000 ft). By 1951, the US Army design specification required a single or two-place cockpit concept for use in front-line reconnaissance and for air rescue operations. The story of the Canadair CL-84 would not be complete without briefly acknowledging a few of the design accomplishments in the field of military and civilian (NACA / NASA) research with deflected slipstream and tilt wing V/STOL aircraft. Among the actual flight-tested antecedents to the CL-84 were the following: (Compiled by Bill Upton) Vertol 76 VZ-2A Tilt Wing In 1956, Vertol was contracted by the Office of Naval Research and the US Army Transportation Corps to research, build and study a functioning tilt wing concept aircraft. On the short-span, rectangular planform wing, dual 2.9 m (9.5 ft) diameter propellers were powered by a single Lycoming YT53-L-1 turboshaft engine mounted on the top of the uncovered framework of the fuselage. The two-man crew and dual aircraft controls were initially enclosed inside a Perspex bubble from a Bell Model 47 Vertol 76 VZ-2A at NASA Langley Research Center (NASA Photo) helicopter. Small ducted fans on the tail provided lateral and longitudinal control in the transition and hover portions of flight. Its first VTOL flight occurred on 13 April 1957. The first conventional, horizontal flight occurred on 7 January 1958, then the VZ-2A performed the first ever successful transition of a tilt-wing aircraft on 18 July. Following the contracted flight-test career in which more than 450 flights had been performed, the pioneering VZ-2A was sent to the NACA (later NASA) Langley Research Center for continued studies. Ryan Model 92 VZ-3RY Vertiplane Deflected Slipstream The Ryan Aeronautical Company was awarded a joint contract in 1956 by the Office of Naval Research, the US Army, and NACA to build and test one of the first of a line of deflected slipstream V/STOL aircraft concepts. Large, double-slotted retractable flaps along the trailing edge of the short wing span extended rearwards and far below, deflecting the slipstream from the two three-bladed wooden propellers, which were driven by a single 1,000 shp Lycoming T53-L-1 turboshaft engine. Large, downward facing wing Ryan VZ-3RY at the NASA Ames Research Center (NASA Photo) endplates on the high-wing configuration contained the airflow from the propellers under the wing. During the hover portions of flight, a universally jointed exhaust-deflector was mounted to the rear of the jet exhaust to provide directional stability. The single seat flying test-bed research aircraft was rolled out and performed some taxiing trials in February 1958, but it wasn’t until 21 January 1959 that a conventional flight was attempted. Later, inflight transitions and hovers were demonstrated, yet it never performed a vertical take-off.