Cessna U-3A Blue Canoe
Twin-engine six-seat cantilevered low-wing tricycle-gear cabin military utility aircraft, U.S.A.
Archive Photos 
[Cessna U-3A "Blue Canoe" (AF 57-5869) c.2002 at the Hill Aerospace Museum, Hill AFB, Salt Lake City, UT (Photo by John Shupek]
Cessna 310 
- Cessna 310/320, U-3
- Role: Twin-engined cabin monoplane
- Manufacturer: Cessna
- First flight: January 3, 1953
- Primary users: General Aviation, United States Air Force
- Produced: 1954-1980
- Number built: 6,321
- Unit cost: US $147,750 (normally aspirated version, 1978 price)
The Cessna 310 is an American six-seat, low-wing, twin-engined monoplane that was produced by Cessna between 1954 and 1980. It was the first twin-engined aircraft that Cessna put into production after World War II.
The 310 first flew on January 3, 1953 with deliveries starting in late 1954. The sleek modern lines of the new twin were backed up by innovative features such as engine exhaust thrust augmenter tubes and the storage of all fuel in tip tanks in early models. In 1964, the engine exhaust was changed to flow under the wing instead of the augmenter tubes, which were considered to be noisy.
Typical of Cessna model naming conventions, a letter was added after the model number to identify changes to the original design over the years. The first significant upgrade to the Cessna 310 series was the Cessna 310C in 1959, which introduced more powerful 260 hp (194 kW) Continental IO-470-D engines. In 1960 the Cessna 310D featured swept back vertical tail surfaces. An extra cabin window was added with the Cessna 310F.
The Cessna 320 Skyknight was developed from the Cessna 310F, which featured turbocharged TSIO-470-B engines and a fourth cabin side-window. The Cessna Skyknight was in production between 1961 and 1969 (the Cessna 320E was named the Executive Skyknight), when it was replaced by the similar Cessna Turbo 310.
The Cessna 310G was certified in 1961 and introduced the canted wingtip fuel tanks found on the majority of the Cessna twin-engined product line, marketed as stabila-tip tanks by Cessna because they were meant to aid stability in flight. A single side window replaced the rear two windows on the Cessna 310K (certified in late 1965), with optional three-blade propellers being introduced as well. Subsequent developments included the Cessna 310Q and turbocharged Cessna T310Q with a redesigned rear cabin featuring a skylight window, and the final Cessna 310R and Cessna T310R, identifiable by a lengthened nose containing a baggage compartment. Production ended in 1980.
Over the years there were several modifications to the Cessna 310 to improve performance. Noted aircraft engineer Jack Riley produced two variants, The Riley Rocket 310 and the Riley Turbostream 310. Riley replaced the standard Continental 310 hp (230 kW) engines with Lycoming TIO-540 350 hp (261 kW) engines. These turbocharged inter-cooled engines were installed with three-blade Hartzell propellers in a counter-rotating configuration to further increase performance and single-engine safety. At 5,400 lb (2,400 kg). gross weight the aircraft had a weight to power ratio of 7.71 lb (3.50 kg). per horsepower. This resulted in a cruising speed of 260 knots (480 km/h) at 18,000 feet (5,500 m) and a 3,000 fpm rate of climb.
Operational History 
The Cessna 310 was a common charter aircraft for the many air taxi firms that sprang up in the general aviation boom that followed World War II. The advantages of the Cessna 310 over its contemporaries, such as the Piper PA-23, were its speed, operating costs and after market modifications such as the Robertson STOL kits which made it popular worldwide for its bush flying characteristics. It could use short runways while at the same time carrying a large useful load of 2,000 lb (910 kg) or more, at high speeds for a twin engine piston aircraft.
In 1957, the United States Air Force (USAF) selected the Cessna 310 for service as a light utility aircraft for transport and administrative support. The USAF purchased 160 unmodified Cessna 310A aircraft with the designation Cessna L-27A and unofficially nicknamed Blue Canoe, later changed to Cessna U-3A in 1962. An additional 36 upgraded Cessna 310 designated Cessna L-27B (later U-3B) were delivered in 1960-61; these aircraft were essentially military Cessna 310Fs and as such equipped with the more powerful 260 hp (194 kW) engines and can be identified by their extra cabin windows, longer nose and swept vertical fin. A USAF study after one year of operational service found the Cessna U-3A had direct operating costs of less than $12 an hour. Some USAF aircraft were later transferred to the U.S. Army and US Navy and the type continued in U.S. military service into the mid-1970s.
- Cessna 310: Production aircraft powered by two 240 hp (180 kW) Continental O-470-B engines, 547 built.
- Cessna 310A: Military version of the Cessna 310 for the United States Air Force, designated Cessna L-27A and later Cessna U-3A, 160 built.
- Cessna 310B: Cessna 310 with new instrument panel, O-470-M engines and minor changes, 225 built.
- Cessna 310C: Cessna 310B with 260 hp (190 kW) IO-470-D engines, increased takeoff weight and minor changes, 259 built. Unit cost $59,950 in 1959
- Cessna 310D: Cessna 310C with swept vertical tail and minor detail changes, 268 built.
- Cessna 310E: Military version of the Cessna 310F, designated the Cessna L-27B and later Cessna U-3B, 36 built.
- Cessna 310F: Cessna 310D with extra cabin window each side, pointed nose, new tip tank shape and other minor changes, 156 built.
- Cessna 310G: Cessna 310F with slimline tip tanks, six-seat cabin, an increased takeoff weight and detail changes, 156 built.
- Cessna 310H: Cessna 310G with increased takeoff weight and enlarged cabin interior, 148 built.
- Cessna 310I: Cessna 310H with IO-470-U engines, baggage compartments in rear of engine nacelles and minor detail changes, 200 built.
- Cessna 310J: Cessna 310I with minor detailed changes, 200 built.
- Cessna 310K: Cessna 310J with long 'vista view' side windows, increased takeoff weight and IO-470-V engines, 245 built.
- Cessna 310L: Cessna 310K with single-piece windshield, redesigned landing gear, increased fuel capacity and minor changes, 207 built.
- Cessna 310M: Revised designation for the Cessna 310E.
- Cessna 310N: Cessna 310L with revised instrument panel, optional fuel tanks in engine nacelles, IO-470-V-O engines and minor changes, 198 built.
- Cessna 310P: Cessna 310N with a shorter nosegear leg, ventral fin, and optional turbocharged Continental TSIO-520-B engines, 240 built.
- Cessna 310Q: Cessna 310P with takeoff weight increased to 5,300 lb (2,400 kg) and detailed changes, from the 401st aircraft fitted with a bulged rear cabin roof with rear view window, 1160 built.
- Cessna 310R: Cessna 310Q with three-bladed propellers, lengthened nose with baggage compartment, 5,500 lb (2,500 kg) takeoff weight and 285 hp (213 kW) IO-520-M engines, 1332 built.
- Cessna 310S: Original designation for the Cessna 320.
- Cessna 320 Skyknight: Enlarged version of the Cessna 310F with six seats, larger cabin and two turbocharged engines, 110 built.
- Cessna 320A Skyknight: Cessna 320 with stabil-tip fuel tanks and minor changes, 47 built.
- Cessna 320B Skyknight: Cessna 320A with nacelle baggage lockers and minor changes, 62 built.
- Cessna 320C Skyknight: Cessna 320B with a longer cabin, optional seventh seat and minor changes, 73 built.
- Cessna 320D Executive Skyknight: Cessna 320C with reshaped rear windows and 285 hp (213 kW) TSIO-520-B engines, 130 built.
- Cessna 320E Executive Skyknight: Cessna 320D with pointed nose, single piece windshield, modified landing gear, increased takeoff weight and minor changes, 110 built.
- Cessna 320F Executive Skyknight: Cessna 320E with minor changes, 45 built.
- Cessna L-27A: United States military designation for the Cessna 310A, later changed to Cessna U-3A.
- Cessna L-27B: United States military designation for the Cessna 310E/310M, later changed to Cessna U-3B.
- Cessna U-3A: Cessna L-27A redesignated in 1963.
- Cessna U-3B: Cessna L-27B redesignated in 1963.
- Riley 65: Cessna 310 to 310G by fitting two 240-260 hp (179-194 kW) Continental O-470D/-470M engines.
- Riley Super 310: Conversion of Cessna 310/320 by fitting two 310 hp (231 kW) Continental TSIO-520-J/-N engines.
- Riley Turbostream: Conversion of Cessna 310 by fitting two 350 hp Lycoming engines.
- Riley Rocket: Conversion of Cessna 310 by fitting two 290 hp (216 kW) Lycoming IO-540-A1A5 engines and more fuel.
Civil Operators 
The aircraft is popular with air charter companies and small feeder airlines, and is operated by private individuals and companies.
Military Operators 
Countries known to have operated the Cessna U-3/310 include.
- Argentina: Argentine Air Force - Cessna 310 and Cessna 320 models.
- Republic of the Congo:
- France: French Air Force - 12 operated
- Haiti: Armed Forces of Haiti
- Indonesia: Indonesian Air Force, Indonesian Army Aviation
- Madagascar: Air Force of Madagascar - One Cessna 310R
- Mexico: Mexican Naval Aviation
- Peru: Peruvian Navy
- Philippines: Philippine Air Force
- Saudi Arabia:
- Tanzania: Tanzanian Air Force
- United States: United States Air Force received 196 Cessna L-27A and Cessna L-27B (later redesignated Cessna U-3A and Cessna U-3B); United States Army received 25 ex-US Air Force Cessna L-27As (later Cessna U-3As) and at least 13 Cessna L-27Bs (later Cessna U-3B) from 1960.
- Uruguay: Uruguayan Air Force (One Cessna 310R)
- Venezuela: Venezuelan Navy
- Zaire: Zaire Air Force
Specifications (1956 Cessna model 310) 
- Crew: one
- Capacity: four passengers
- Length: 27 ft 0 in (8.23 m)
- Wingspan: 35 ft 0 in (10.67 m)
- Height: 10 ft 6 in (3.20 m)
- Wing area: 175 sq ft (16.3 m²)
- Empty weight: 2,850 lb (1,293 kg)
- Gross weight: 4,600 lb (2,087 kg)
- Powerplant: 2 × Continental O-470-B horizontally opposed piston engines, 240 hp (180 kW) each
- Maximum speed: 220 mph (354 km/h; 191 kn)
- Cruise speed: 205 mph (178 kn; 330 km/h)
- Range: 1,000 mi (869 nmi; 1,609 km)
- Service ceiling: 20,000 ft (6,096 m)
- Rate of climb: 1,700 ft/min (8.6 m/s)
- Shupek, John. Photos by John Shupek, Copyright © 2002 Skytamer Images (Skytamer.com). All Rights Reserved
- Wikipedia. Cessna 310
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