| 336 Skymaster 337 Super Skymaster | |
|---|---|
| Role | Civil utility aircraft |
| Manufacturer | Cessna |
| First flight | 1961 |
| Status | Active service |
| Primary user | Private individuals and organizations |
| Produced | 1963-1982 |
| Number built | 2,480 |
| Variants | O-2 Skymaster |
The Cessna Skymaster is a twin-engine civil utility aircraft built in a push-pull configuration. Instead of the engines being mounted on the wings, one is mounted on the nose and the other at the rear of the pod-style fuselage. The stabilizers are mounted on twin booms that extend from the wings. The rear engine is between the booms. The combination of a tractor and a pusher engine produces a unique sound.
Development
editThe first model of the Skymaster was the 336. It had fixed landing gear and first flew in February 1961. It went into production in 1963 and 195 were produced to mid 1964.
In 1965 Cessna introduced the model 337 Super Skymaster. This aircraft was larger, had more powerful engines, retractable landing gear and a dorsal air scoop for the rear engine (the "Super" was subsequently dropped from the name). In 1967 the turbocharged T337 was introduced and in 1972 the pressurized T337G entered production. Cessna built 1,859 standard and turbocharged Skymasters and 332 T337Gs. In addition, they built 513 military O-2 versions.
Cessna production ended in 1982 but Skymaster production continued with Reims in France with the FTB337 STOL and the military FTMA Milirole. Reims produced a total of 94 Skymasters.
After a 20-year hiatus the centerline thrust, pod and twin-boom concept has been revived in the Adam A500.
Design
editWith both engines along the centerline of the airplane, the Skymaster is easier to handle if one engine quits, compared to conventional twin-engine aircraft which will yaw into the dead engine. When there is a loss of power, use of the instruments to determine which engine has failed is more critical in a Skymaster, since the pilot can see only one engine and sound may not provide enough information. The Skymaster is also controllable at lower airspeeds than a comparable conventional twin. There is no minimum controllable speed advisory (Vmc) on the airspeed indicator. Nevertheless, the Skymaster requires a multi-engine-rated pilot, who must be trained to manage both engines.
Notwithstanding the more docile handling characteristics, the Skymaster accident statistics are comparable to those of conventional twins. Some believe that it is because pilots think of it as a simple aircraft and fail to give it the attention it deserves. For instance, many of the accidents are due to fuel-management errors, despite the fact that the fuel system is unremarkable.
Extended taxiing on hot days can cause the rear engine to overheat and sometimes to quit; this led to some accidents when pilots, unaware of the shutdown, attempted take-off on the nose engine alone even though the single-engine take-off roll exceeded the runway length (a directive requiring acceleration of the rear engine first has corrected this).
The Skymaster produces a unique unmistakable sound. All rear-engined aircraft produce a characteristic sound as the propeller slices through turbulent air coming off the airframe. Since the Skymaster also has a nose engine, with a propeller that operates in undisturbed air, its sound is different from a pure pusher.
Operational history
editThe California Department of Forestry and Fire Protection uses various models of the 337 Skymaster as spotter planes during firefighting operations.
In 1994 the Cuban exile group Hermanos al Rescate (Brothers to the Rescue) used Skymasters to drop life-saving supplies to rafters attempting to cross the Florida Straits to defect from Cuba. They were also used to violate Cuban airspace, flying over Cuba's capital, Havana, and dropping leaflets with anti-Castro propaganda. They chose Skymasters because they were easier to control at slow speeds than conventional twin-engine aircraft. One plane contacted the water (it is difficult to judge altitude over relatively calm water), damaging the landing gear doors and the nose propeller. Since the rear engine is mounted higher, it wasn't damaged and the aircraft was able to return to Florida to make a belly landing.
In 1996 two of the Brothers to the Rescue's Skymasters were shot down by the Cuban Air Force over international waters. One by a MiG-23 and another by a MiG-29.
Aircraft type clubs
editThe Cessna Skymaster series is supported by a number of Aircraft Type Clubs, including the Skymaster Owners and Pilots Association and the Cessna Pilots Association.
Variants
editCessna
edit- 327 Mini Skymaster - reduced scale version of the 337, with cantilever wings (instead of the strut-braced configuration), one built. The cantilever wing was not stiff enough to prevent "boom bounce", a persistent up-down movement of the empennage after any disturbance due to turbulence or pilot input. This problem, together with an unacceptably high estimated cost of production, led to the factory decision to cancel further work on this program.[citation needed] Only known prototype was delivered to NASA to serve as a full blown model for wind tunnel testing.
- 336 Skymaster - production version powered by two 195 hp Continental IO-360-A engines, 195 built.
- 337 Super Skymaster - 336 with retractable undercarriage, re-designed nose cowling and new rear engine intake, and greater wing angle of incidence, powered by two 210hp Continental IO-360-C engines, 239 built.
- 337A Super Skymaster - 337 with minor detail changes, 255 built.
- 337B Super Skymaster - 337A with increased take-off gross weight, option belly cargo pack and optional turbocharged engines, 230 built.
- 337C Super Skymaster - 337B with a new instrument panel and increased take-off gross-weight, 223 built.
- 337D Super Skymaster - 337C with minor detail changes, 215 built.
- 337E Super Skymaster - 337D with cambered wingtips and minor changes, 100 built.
- 337F Super Skymaster - 337E with increased take-off gross weight, 114 built.
- 337G Super Skymaster - 337F with split airstair entry door, smaller rear side windows, improved flaps, larger fron propeller, powered by a Continental IO-360-G engine, 352 built.
- T337G Super Skymaster - 337G with presurised cabin and turbocharged engines, 292 built.
- 337H Skymaster - 337G with minor changes and optional turbocharged engines, 136 built.
- P337H Pressurised Skymaster - T337G with minor changes, 64 built.
- 337M - US military version, designated O-2 Skymaster in service, 513 built.
- O-2A - US military designation of the 337M Forward air control, observation aircraft for the US Air Force.
- O-2B : Psychological warfare version for the US Air Force (31 former civil aircraft not 337Ms).
- O-2T : Twin turboprop-powered version of the O-2.
- O-TT :
- Sentry O2-337 : Military version.
- Lynx : Armed military version for the Rhodesian Air Force.
- T337H-SP
Reims Cessna
edit- F337E Super Skymaster - Reims-built 337E, 24 built.
- F337F Super Skymaster - Reims-built 337F, 31 built.
- F337G Super Skymaster - Reims-built 337G, 29 built.
- FT337G Super Skymaster - Reims-built T337G, 22 built.
- F337H - Reims-built 337H, one built.
- FP337H Pressurised Skymaster - Reims-built P337H, 1 built.
- FTB337G Milirole - Reims-built military F337G with Robertson STOL modifications and underwing hardpoints, 61 built.
- Lynx : Rhodesian designation for 21 FTB337Gs delivered to the Rhodesian Air Force.
Conversions/modifications
edit- One 337 radically modified by Conroy Aircraft as a STOL cargo plane. Front engine replaced with an Garrett AiResearch TPE-331 and rear engine with an extended cargo pod.
- The AVE Mizar flying car created by Advanced Vehicle Engineers by attaching the wings, tail, and rear engine of a Skymaster to a Ford Pinto outfitted with aircraft controls and instruments.
- Summit Sentry - Summit Aviation built a militarized Skymaster as the O2-337 in 1980, and sold a few examples to the Haiti Air Corps and the Thai Navy
- Spectrum Aircraft Corporation of Van Nuys, California made an extensive conversion of a Reims FTB337G in the mid 1980s - the Spectrum SA-550. They removed the nose engine, lengthened the nose and replaced the rear engine with a turboprop. This aircraft (serial number 61) is currently registered to Basler Turbo Conversions of Oshkosh, Wisconsin.
Military Operators
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Burkina Faso
Chad
Chile: Chilean Air Force
Colombia
Costa Rica
Dominican Republic
Ecuador
El Salvador
Haiti
Jamaica
Mexico
Peru
Portugal: Portuguese Air Force (32 FTB-337G)
These aircraft were bought in 1973 by Portugal to replace its aging Dornier Do-27 that were being intensively used in the Portuguese Colonial War, but the first deliveries only arrived in December 1974 - after the end of the war. The last Skymaster in service with the Portuguese Air Force was retired in July 25, 2007.
South Africa: South African Air Force
South Korea
Sri Lanka
Thailand: Thai Air Force
Togo: Togo Air Force
United States
Zimbabwe (Rhodesia)
- Terrorist organizations
Specifications (337D)
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General characteristics
- Crew: 1
- Capacity: 5 passengers
- Length: 29 ft 9 in (9.07 m)
- Wingspan: 38 ft 0 in (11.58 m)
- Height: 9 ft 4 in (2.84 m)
- Wing area: 201 sq ft (18.7 m2)
- Empty weight: 2,655 lb (1,204 kg)
- Max takeoff weight: 4,400 lb (2,000 kg)
- Powerplant: 2 × Continental IO-360-C piston engines, 210 hp (160 kW) each
Performance
- Range: 760 mi (1,220 km, 664 nmi)
- Service ceiling: 19,500 ft (5,940 m)
- Rate of climb: 1,200 ft/min (6.1 m/s)
- Power/mass: ()
External links
editSee also
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Related development
Aircraft of comparable role, configuration, and era