Cessna UC-78B Bobcat
Twin-engine five-seat low-wing light transport/training aircraft, U.S.A.

Archive Photos ¹

Cessna UC-78B "Bobcat" (AF 42-71626) c.2001 at the USAF Museum, WPAFB, Dayton, OH (Photos by John Shupek)

Cessna UC-78B "Bobcat" (AF 43-32578, N44795) at the MCAS El Toro Airshow (Photos by John Shupek)

Series Overview ²

• Cessna UC-78B Bobcat
• Role: Five-seat light transport
• Manufacturer: Cessna Aircraft Company
• First flight: March 26, 1939 (T-50)
• Primary users: United States Army Air Forces, Royal Canadian Air Force, United States Navy
• Produced: 1939-1944
• Number built: 5,422

The Cessna AT-17 Bobcat was a Twin-engine advanced trainer aircraft designed and made in the United States, and used during World War II to bridge the gap between Single-engine trainers and Twin-engine combat aircraft. The AT-17 was powered by two Jacobs R-755-9 radial piston engines. The commercial version was the Model T-50, from which the AT-17 was developed.

Design and Development ²

The AT-17 was a military version of the commercial Cessna T-50 light transport. The Cessna Airplane Company first produced the wood and tubular steel, fabric-covered T-50 in 1939 for the civilian market, as a lightweight and low-cost twin for personal use where larger aircraft such as the Beech 18 would be too expensive. A low-wing cantilever monoplane, it featured retractable main landing gear and wing trailing edge flaps, both electrically actuated. The wing structure was built up of laminated spruce spar beams with spruce and plywood ribs. The fixed tailwheel is non-steerable and full-swivelling. The prototype T-50 made its maiden flight on 26 March 1939.

In 1940, the United States Army Air Corps ordered them under the designation AT-8 as multi-engine advanced trainers.

Operational History ²

Thirty-three AT-8s were built for the U.S. Army Air Corps, and production continued under the designation AT-17 reflecting a change in equipment and engine types. In 1942, the U.S Army Air Force (the successor to the Air Corps from June 1941) adopted the Bobcat as a light personnel transport and those delivered after January 1, 1943 were designated UC-78s. By the end of World War II, Cessna had produced more than 4,600 Bobcats for the U.S. military, 67 of which were transferred to the United States Navy as JRC-1s. In addition, 822 Bobcats had been produced for the Royal Canadian Air Force as Crane Is, many of which were used in the British Commonwealth Air Training Plan. The aircraft did not last long in North American postwar military service. Few (if any) Bobcats were in service with the United States Air Force when it was formed in September, 1947. Surviving military aircraft were declared obsolete in 1949.

Dubbed the "Bamboo Bomber" by the pilots who flew them, it was one of the aircraft featured in the popular television series "Sky King" of the early-to-mid 1950s. The aircraft was replaced in later episodes by the T-50’s successor, the all-metal Cessna 310.

Postwar, surplus AT-17s and UC-78s could be converted by CAA-approved kits to civilian standard aircraft allowing their certification under the T-50s original Type Certificate (ATC- 722, issued 3-24-1940). They were used by small airlines, charter and "bush" operators and private pilots. Some were operated on floats. By the 1970s, the number of airworthy aircraft had dwindled as they were made obsolete by more modern types and by the maintenance required by their aging wood wing structures and fabric covering. Since then, several have been restored by antique airplane enthusiasts.

In August 2009, FAA records show 378 T-50s, 10 AT-17s and 30 UC-78s are listed on the FAA registration database. In the postwar years, Bobcats continued in military service with Brazil and the Nationalist Chinese.

Variants ²

• T-50: Company design number. Five-seat Twin-engine commercial transport aircraft, fitted with Jacobs L-4MB radial piston engines.
• AT-8: Military trainer version of the T-50 with two 295 hp (220-kW) Lycoming R-680-9 radial piston engines, 33 built.
• AT-17: As the AT-8 but powered by 245 hp (183 kW) Jacobs R-755-9 (L-4) engines, 450 built some later converted to AT-17E.
• AT-17A: As the AT-17 but with metal propellers and reduced weight, 223 built. 182 to Canada as Crane IAs and later conversion to AT-17Fs.
• AT-17B: As the AT-17A but with equipment changes, 466 built. Subsequent aircraft were built as UC-78Bs.
• AT-17C: As the AT-17A but different radio equipment, 60 built.
• AT-17D: As the AT-C with equipment changes, 131 built.
• AT-17E: AT-17 with gross weight limited to 5,300 lb (2,400 kg).
• AT-17F: AT-17A with gross weight limited to 5,300 lb (2,400 kg).
• AT-17G: AT-17B with gross weight limited to 5,300 lb (2,400 kg).
• C-78: Military transport version for the United States Army Air Forces, redesignated UC-78 in 1943, 1354 built.
• UC-78: C-78 redesignated in 1943; variable-pitch propellers.
• UC-78A: 17 impressed civilian T-50s.
• UC-78B: Originally the AT-17B, wooden propellers and reduced weight, 1806 built.
• UC-78C: Originally the AT-17D, same as UC-78B with equipment changes, 196 built and 131 AT-17Ds redesignated.
• JRC-1: Navy light transport version of the UC-78 with two Jacobs-9 engines, 67 delivered.
• Crane I: Royal Canadian Air Force designation for T-50s with minor equipment changes, 640 delivered as light transports.
• Crane 1A: 182 AT-17As delivered to Canada under lend-lease.
• P-7: An experimental variant of the T-50 with more powerful 300 hp (220 kW) Jacobs L-6MB engines, and plywood covered tailplane and wings, one aircraft only first flown June 2, 1941.
• P-10: 1941 advanced bomber trainer with modified fuselage, sliding canopy and 330 hp (250 kW) Jacobs engines, 1 built.

Operators ²

• Brazil: Brazilian Air Force (operated 39 from 1943-1956)
• Canada: Royal Canadian Air Force (operated 744 from 1941-1949); Queen Charlotte Airlines
• Costa Rica: Air Force of Costa Rica (operated one in 1948)
• Ethiopia: Ethiopian Air Force (operated two from 1946-1965)
• France: French Air Force & French Navy (operated eight from 1943-1951)
• Guatemala: Guatemalan Air Force (received one in 1949)
• Haiti: Haitian Air Force (operated four from 1943-1963)
• Nicaragua: Nicaraguan Air Force (received two in 1947)
• North Yemen: Yemeni Air Force (operated three from 1950-1958)
• Republic of China: Republic of China Air Force (operated 15 from 1946-1950)
• Peru: Peruvian Air Force (operated nine from 1945-1958)
• Poland: LOT Polish Airlines (operated 14 from 1946-1950)
• United States: Civil Aeronautics Authority, United States Army Air Corps/United States Army Air Forces, United States Navy, Northern Consolidated Airlines, Wiggins Airways, Wisconsin Central Airlines

Cessna UC-78 Bobcat Specifications ³

Type

• Twin-engine Advanced Training monoplane (AT-17 "Bobcat" or "Crane") or light Personal Transport (UC-78 or JRC-1).

Wings

• Low-wing cantilever monoplane.
• NACA 23012 wing-section.
• Wing in one piece with laminated spruce spars, spruce ribs, plywood-covered leading-edge at wing-tips, the whole covered with fabric.
• Spruce compression members and stainless-steel drag wire internal bracing.
• Trailing-edge flaps between ailerons and fuselage.
• Flaps are a wooden construction and electrically-operated.
• Statically and aerodynamically-balanced ailerons of similar construction to flaps.

Fuselage

• Rigidly-braced welded steel-tube structure covered with fabric over a light wooden secondary framework.

Tail Unit

• Cantilever monoplane type.
• Tail-plane and fin of wooden construction.
• Rudder and elevators have welded steel-tube frames.
• The whole unit is covered with fabric.
• Both rudder and elevators incorporate metal remotely-controllable balanced type twin-tabs.

Landing Gear

• Retractable type.
• Two independent units, incorporating Bendix air-oil shock-absorbers beneath each engine nacelle.
• Wheels retracted backwards into engine nacelles by single electric motor, roller chains and screw-jack arrangement.
• Hydraulic expander-type wheel brakes.

Power Unit

• Two 225 hp Jacobs R-755-9 seven-cylinder radial air-cooled engines attached rigidly to welded steel tube mounting.
• Engine mountings are attached to welded steel front nacelle truss through four vibration-absorber bushings.
• NACA cowlings.
• Hamilton-standard constant-speed airscrews.
• Fuel tanks in wing.
• Normal fuel capacity 129 U.S. gallons (453 L).
• Maximum capacity 160 U.S. gallons (605 L).

Accommodation

• Enclosed cabin seating four or five.
• Front pair of seats have dual controls.
• The commercial T-50 model was originally designed for a gross weight of 5,100 lbs (2,315 kg).
• Current military models are designed for a gross weight of 5,700 lbs (2,588 kg).
• The loading and performance given below are for the commercial version.

Dimensions

• Span: 41 ft 11 in (12.8 m)
• Length: 32 ft 9 in (10 m)
• Height: 9 ft 11 in (3.3 m)
• Wing area: 295 ft² (27.5 m²)

Weights and Loadings

• Weight empty: 3,500 lbs (1,588 kg)
• Pay load: 850 lbs (385 kg)
• Disposable load: 1,500 lbs (680 kg)
• Weight loaded: 5,100 lbs (2,315 kg)
• Wing loading: (16.9 lbs/ft² (82.5 kg/m²)
• Power loading: 10.2 lbs/hp (4.6 kg/hp)

Performance

• Maximum speed at sea level: 195 mph (314 km/h).
• Cruising speed at sea level: 175 mph (280 km/h).
• Cruising speed at 7,500 ft (2,288 m): 195 mph (307 km/h).
• Landing speed with flaps: 55 mph (88 km/h).
• Initial rate of climb: 1.525 ft/min (460 m/min).
• Service ceiling: 22,000 ft (600 (6710 m).
• Cruising range: 750 miles (1,200 km).

References

1. Shupek, John. Photos, copyright © 2009 Skytamer Images (Skytamer.com). All Rights Reserved
2. Wikipedia, the free encyclopedia. Cessna AT-17 Bobcat
3. Bridgman, Leonard. Jane’s All the World’s Aircraft 1943-44, Cessna: The Cessna Bobcat, London: Sampson Low, Marston & Co., Ltd., 1944, pp 171c.