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Cessna Skymaster

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Cessna 336 Skymaster
337 Super Skymaster
Cessna 337 Skymaster
Role Personal use andair taxiaircraft
National origin United States
Manufacturer Cessna
Reims Aviation
First flight February 28, 1961
Introduction 1962
Produced 1963–1982
Number built 2,993[1]
Variants Cessna O-2 Skymaster
Conroy Stolifter
Spectrum SA-550

TheCessna Skymasteris an American twin-engine civil utilityaircraftbuilt in apush-pull configuration.Itsenginesare mounted in the nose and rear of its pod-style fuselage.Twin boomsextend aft of the wings to thevertical stabilizers,with the rear engine between them. Thehorizontal stabilizeris aft of thepusher propeller,mounted between and connecting the two booms.[1]The combinedtractorandpusherengines produce centerline thrust and a unique sound.[2]TheCessna O-2 Skymasteris a military version of the Cessna 337 Super Skymaster.

Development

[edit]
Retracting landing gear

The first Skymaster, Model 336 Skymaster, had fixed landing gear and initially flew on February 28, 1961.[3][4]It went into production in May 1963[1]with 195 being produced through mid-1964.[2]

In February 1965, Cessna introduced the Model 337 Super Skymaster.[5]The model was larger, and had more powerful engines, retractable landing gear, and a dorsal air scoop for the rear engine. (The "Super" prefix was subsequently dropped from the name.)[2]In 1966, the turbocharged T337 was introduced, and in 1973, the pressurized P337G entered production.[2]

Cessna built 2993 Skymasters of all variants, including 513 militaryO-2versions.[1]Production in America ended in 1982, but was continued byReimsin France, with the FTB337STOLand the military FTMAMilirole.[4]

Design

[edit]
Fuselage close-up with door open
Flight deck

The Skymaster handles differently from a conventional twin-engine aircraft, primarily in that if an engine fails, the plane will notyawtoward that engine. Without the issue of differential thrust inherent to conventional (engine-on-wing) twins, engine failure on takeoff will not produce yaw from the runway heading. With no one-engine-outminimum controllable speed(Vmc), in-flight control at any flying speed with an engine inoperative is not as critical as it is with engines on the wing with the associated leverage; however, performance in speed and, particularly, rate of climb are affected. Flying a Skymaster requires a pilot to hold a multiengine rating, although many countries issue a special "centerline thrust rating" for the Skymaster and other similarly configured aircraft.[2]

Ground handling requires certain attention and procedures. The rear engine tends to overheat and can quit whiletaxiingon very hot days.[6]Accidents have occurred when the runway is shorter than the single-engine take-off roll and pilots, unaware of a rear engine shutdown, have attempted take-off on the nose engine alone.[7]Federal Aviation AdministrationAirworthiness Directive77-08-05 prohibits single-engine take-offs and requires the installation of a placard marked "DO NOT INITIATE SINGLE ENGINE TAKEOFF".[8]

The Skymaster's unique sound is made by its rearpusher propellerslicing through turbulent air from the front propeller and over the airframe while its fronttractor propelleraddresses undisturbed air.[2]

Operational history

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From 1976 until the middle 1990s, theCalifornia Department of Forestry and Fire Protectionused O-2 variants of the 337 Skymaster as tactical aircraft during firefighting operations. These were replaced with North AmericanOV-10 Broncos,starting in 1993.[9]

During theRhodesian Bush War,the Reims-Cessna FTB 337G 'Lynx' was the main light attack aircraft used byRhodesian Security Forcesduring Fire Forcecounterinsurgencyair assaultmissions, which began in 1974. The Lynxes were armed with twin Browning.303 machine guns mounted above the wing and 37mmSNEBrockets, locally made Mini "Alpha" Bombs (cluster bombs), Mini "Golf" Bombs (450 lb (200 kg) blast and shrapnel bomb) andFrantan(a napalm variant carried in frangible drop tanks) bombs.[10]

Brothers to the Rescue

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Main article:Brothers to the Rescue

From 1991 until 2001 theCubanexile groupHermanos al Rescate(Brothers to the Rescue) used Skymasters, among other aircraft, to flysearch and rescuemissions over theFlorida Straitslooking for rafters attempting to cross the straits todefectfrom Cuba, and when they found them, dropped life-saving supplies to them. Rescues were coordinated with theUS Coast Guard,which worked closely with the group. They chose Skymasters because their high wing offered better visibility of the waters below, they were reliable and easy to fly for long-duration missions (averaging 7 hours), and they added a margin of safety with twin-engine centerline thrust. In 1996, two of the Brothers to the Rescue Skymasters wereshot downby theCuban Air Forceover international waters. Both aircraft were downed by aMiG-29,while a second jet fighter, aMiG-23,orbited nearby.[11]

Variants

[edit]

Cessna has historically usedmodel yearssimilar to U.S. auto manufacturers, with sales of new models typically starting a few months prior to the actual calendar year.

336 Skymaster
Original variant first flown in 1961 and introduced for the 1963 and 1964 model years. The 336 had a six-seat cabin and was powered by two 195 hp (145 kW) Continental IO-360-A engines. Production aircraft differed from the prototypes in that they had a roomier cabin and a redesigned rear engine cowling to improve engine cooling and reduce cabin noise. Gross weight was 3,900 lb (1,800 kg).[12][13]A total of 197 built; 2 prototypes and 195 production aircraft (102 in 1963 and 93 in 1964).[14][15]
337 Super Skymaster
The 1965 model year brought major changes to the Skymaster, which led to a new model number, 337, being assigned. The most significant change was the addition of retractableundercarriagesimilar to that of theCessna 210 Centurion,which sat four inches lower than the 336 for ease of entry/exit. Other changes included a redesigned nosecowlingand new rear engine intake, greater wingangle of incidence,shortened ventral tail fins, increased elevator chord, and an increased gross weight of 4,200 lb (1,900 kg). The 337 was powered by two 210 hp (160 kW) Continental IO-360-C or IO-360-D engines.[12][13]239 total built; 1 prototype and 238 production aircraft.[15][16]
337A Super Skymaster
1966 model year with canted engine instruments and rotary-type door latches.[12][13]284 built.[15][16]31 were later modified toMC337Astandard with loudspeakers and leaflet dispensers for use by theUnited States Air Forceas theO-2B Skymaster.[4][12]
USAFO-2A(M337B) over Panama
337B/T337B Super Skymaster
1967 model year with improved brakes, 38A alternators, a redesigned cabin heating system, a split-bus electrical system, and an increased gross weight of 4,300 lb (2,000 kg). A version powered by turbocharged 210 hp (160 kW) Continental TSIO-360-A engines was also offered as theT337B.[12][13]231 built, plus 479M337Bmilitary variants as the O-2A Skymaster.[4][15][16]
337C/T337C Super Skymaster
1968 model year with a new instrument panel, improved seat belts, and an increased gross weight of 4,400 lb (2,000 kg) (4,500 lb (2,000 kg) for theT337C).[12][13]223 built.[15][16]
337D/T337D Super Skymaster
1969 model year with reduced elevator chord and increased elevator up travel, electroluminescent instrument panel lighting, and new cowl flap controls. Also offered as the turbochargedT337D.[12][13]215 built.[15][16]
337E/T337E Super Skymaster
1970 model year with conical cambered wingtips, a new fuel quantity system, and an increased gross weight of 4,440 lb (2,010 kg) (4,630 lb (2,100 kg) for theT337E).[12][13]123 built, plus 24 in France byReims Aviationfor the European market as theF337E.[15][16][17]
FTA337E
One aircraft converted from the 20th production F337E.[15]
337F/T337F Super Skymaster
Introduced for the 1971 model year with an increased gross weight of 4,630 lb (2,100 kg) (same as the T337F) a refined instrument panel, a padded glareshield, a front engine access panel, and other minor changes. The 1972 model year introduced nose-mounted landing/taxi lights and minor interior changes. The turbochargedT337Fwas only offered for the 1971 model year.[12][13]147 total built; 83 (1971) and 64 (1972). Reims also built a total of 31 as theF337F;21 (1971) and 10 (1972).[15][16][17]
337G Super Skymaster
Introduced for the 1973 model year with a recontoured nose cap, flush wingtip lights, low-drag front exhaust stack and wing strut fairings, a flush-mounted pitot port on the left wing strut, a splitairstairdoor replacing the cabin and baggage doors, aileron gap seals, and a hydraulic powerpack replacing the engine-driven pump. Power was provided by two 210 hp (160 kW) Continental IO-360-G engines. The 1974 model year introduced recessed parking brake control, a hydraulic gear accumulator, and improved subpanel rocker switches. 1975 introduced an optional 148 US gal (560 L) auxiliary fuel system and theSkymaster IIwith a preferred options package. 1976 introduced a "Camber-Lift" wing, a redesigned instrument panel, and a reworked fuel system with tail boom fuel sump tanks removed. 1977 introduced a new front propeller airfoil and an auxiliary master power switch. A turbocharged version of the unpressurized 337G was not offered.[12][13]354 total built; 88 (1973), 56 (1974), 65 (1975), 77 (1976), and 68 (1977). Reims also built a total of 29 as theF337G;8 (1973), 8 (1974), 5 (1975), 3 (1976), and 5 (1977).[15][16][17]
Reims FT337GP Pressurized Skymaster
P337G Pressurized Skymaster
Also known as theT337G,[note 1]introduced for the 1973 model year as a turbocharged, pressurized version of the 337G. The P337G was powered by two 225 hp (168 kW) TSIO-360-C engines. Like the 337G, the Skymaster II option was also available for the P337G.[12][13]292 total built; 1 (1971 prototype), 148 (1973), 45 (1974), 31 (1975), 32 (1976), and 35 (1977). Reims also built a total of 22 as theFT337GP;8 (1973), 5 (1974), 2 (1975), 2 (1976), and 5 (1977).[15][16][17]
FTB337G
Military variant of the F337G withSierra IndustriesRobertson STOL modifications and underwinghardpoints.Known as theLynxinRhodesian Air Forceservice. 61 built.[4][10][15]
337H/T337H Super Skymaster
Introduced for the 1978 model year with redesigned control wheels and minor interior refinements. The turbocharged version was also offered after a six year absence as theT337H,which was powered by two 210 hp (160 kW) Continental TSIO-360-H engines. TheT337H-SPwas introduced for the 1980 model year and was powered by TSIO-360-JB engines. The 1980 model year replaced the engines of the 337H and T337H with the TSIO-360-GB and TSIO-360-HB, respectively.[12][13][16]140 total built; 58 (1978), 47 (1979 337H/T337H), 1 (1979 T337H-SP prototype), 24 (1980 337H/T337H), and 10 (1980 T337H-SP). Reims also built 2 aircraft in 1978 as theF337H.[15][16][17]
P337H Pressurized Skymaster
Introduced for the 1978 model year as a turbocharged, pressurized version of the 337H powered by two 225 hp (168 kW) TSIO-360-C engines, which were replaced by the TSIO-360-C for the 1980 model year.[12][13]64 total built; 26 (1978), 24 (1979), and 15 (1980). Reims also built 1 aircraft in 1978 as theFT337HP.[15][16][17]
348
Based on the M337B but with two 317 shp (236 kW)Allison 250-B15turboprop engines, a longer span wing, and improved high lift devices. DesignatedO-2T,only a single prototype was built.[18][13]
351
Also known as theO-2TT,a proposed variant of the O-2T with a tandem two-seat cockpit for the pilot and observer. Only a mockup was built.[4][18][13][15]
377/327 Baby Skymaster
Reduced-scale four-seat version of the 337 first proposed in 1965 withcantileverwings replacing the 336/337 strut-braced configuration. It was later redesignated as the Model 327 in 1967 and was first flown in in December of that year. One prototype was built before the project was canceled in 1968 due to lack of commercial interest in the design. The prototype was delivered toNASAto serve as a full-scale model forwind tunneltesting. It was used in a joint Langley Research Center and Cessna project on noise reduction and the use of ducted versus free propellers.[19][12]

Conversions/modifications

[edit]
Ampaire Electric EEL
Hybrid electric aircraftwith the forward piston engine replaced by an electric motor powered by a battery, in aparallel hybridconfiguration. The demonstrator first flew on 6 June 2019, before Hawaiian regional carrierMokulele Airlinesexperiment connectingMauiairports with the aircraft.
AVE Mizar
Flying car,created byAdvanced Vehicle Engineers,was an attachment of Skymaster wings, tail, and rear engine to aFord Pintooutfitted with aircraft controls and instruments.[20]
Conroy Stolifter
An extensive single-turboprop engine STOL cargo plane conversion of the Skymaster. Front engine was replaced with aGarrett AiResearch TPE-331turboprop;rear engine was removed, and its space filled with an extended cargo pod.
Groen RevCon 6-X
Test conversion of a Cessna 337 Skymaster airplane. This aircraft conversion tested the theory of using fixed-wing airplanes as the basic airframes for gyroplanes to reduce cost and shorten development time.
Spectrum SA-550
Built bySpectrum Aircraft CorporationofVan Nuys,California,it was an extensive single-turboprop engine conversion of a Reims FTB337G constructed in the mid 1980s. They removed the nose engine, lengthened the nose, and replaced the rear engine with a turboprop.[21]
Summit Sentry O2-337
Summit Aviation ofMiddletown, Delawarere-manufactured existing used 337 airframes into the militarizedO2-337which includes four wing-mounted NATO standard pylons capable of carrying 350 lb (159 kg) each for 7.62 mm and 12.7 mm gun pods, rocket launchers, bombs, markers and flares. The aircraft was marketed for the target identification and marking, reconnaissance, helicopter escort and aerial photography roles. Examples were sold to theHaitian Air Force,Honduras,Nicaragua,Senegaland theThai Navy.The variant was still in production in 1987.[3]
VoltAero hybrid electric conversion
VoltAero is a startup company formed in September 2017 by theCTOand test pilot of the 2014Airbus E-Fan1.0. The company has been established inRoyan,with support from the FrenchNouvelle-Aquitaineregion. It is developing a hybridelectric aircrafttestbed based on the Skymaster, which is intended to fly in late February 2019. It will be followed up by theVoltAero Cassioprototype in 2020, a clean-sheet, all-composite design.[22]

Military operators

[edit]
Thai NavyT337H-SP
Angola
FAPA/DAA[23]
Burkina Faso
Force Aérienne du Burkina Faso[24]
Colombia
Colombian Air Force[25]
Mozambique
Força Aérea de Moçambique(3 x FTB-337G) - ex-Portuguese Air Force FTB-337G refurbished and offered by the Government of Portugal to Mozambique in 2011 and 2012.[26]
Namibia
Namibian Air Force[citation needed]
Nicaragua
Nicaraguan Air Force[27]
Togo
Togo Air Force[3]
Zimbabwe
Air Force of Zimbabwe[3]

Former military operators

[edit]
Argentina
Gendarmeria Nacional ArgentinaTwo examples, 1965-1986[28]
Bangladesh
Bangladesh Air Force[29]
Chile
Chilean ArmyThree examples, between the end of 1970s and mid-1990s, sold to civilian interests.[citation needed]
Chad
Chadian Air Force[3]
Ecuador
Ecuadorian Air Force[3]
El Salvador
Air Force of El Salvador[3]
Equatorial Guinea
Armed Forces of Equatorial Guinea[30]
Guinea-Bissau
Força Aérea de Guine-Bissau[31]
Haiti
Haitian Air Force[3]
Jamaica
Jamaica Defense Force[3]
Niger
Military of Niger[27]
Mexico
Mexican Air Force[3]
Portugal
Portuguese Air Force[3](32 × FTB-337G): Purchased in 1973 to replace the force's agingDornier Do 27fleet, which had been used intensively in thePortuguese Colonial War.The first 337 deliveries did not arrive until December 1974—after the end of the war. The last Skymaster in service with the Portuguese Air Force was retired on July 25, 2007.
Rhodesia
Rhodesian Air Force[32]
Senegal
Senegalese Air Force[33][unreliable source?]
Sri Lanka
Sri Lanka Air Force[3]

Specifications (337D)

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3-view line drawing of the Cessna T337C Turbo System Super Skymaster
3-view line drawing of the Cessna T337C Turbo System Super Skymaster

Data fromJane's All The World's Aircraft 1969–70[34]

General characteristics

  • Crew:1
  • Capacity:5 passengers
  • Length:29 ft 9 in (9.07 m)
  • Wingspan:38 ft 09 in (11.81 m)
  • Height:9 ft 4 in (2.84 m)
  • Wing area:201 sq ft (18.7 m2)
  • Aspect ratio:7.18:1
  • Airfoil:NACA 2412 at root, NACA 2409 at tip
  • Empty weight:2,655 lb (1,204 kg)
  • Max takeoff weight:4,400 lb (1,996 kg)
  • Fuel capacity:92 US gal (77 imp gal; 350 L) normal, 128 US gal (107 imp gal; 480 L) with auxiliary tanks
  • Powerplant:2 ×Continental IO-360-Cair-cooledflat-sixpiston engine, 210 hp (160 kW) each
  • Propellers:2-bladed McCauley fully-feathering, constant-speed propeller, 6 ft 4 in (1.93 m) diameter

Performance

  • Maximum speed:199 mph (320 km/h, 173 kn) at sea level
  • Cruise speed:144 mph (232 km/h, 125 kn) at 10,000 ft (3,000 m) (econ cruise)
  • Stall speed:69 mph (111 km/h, 60 kn) (flaps and undercarriage down)
  • Range:965 mi (1,553 km, 839 nmi) (econ cruise, normal fuel)
  • Service ceiling:19,500 ft (5,900 m)
  • Rate of climb:1,200 ft/min (6.1 m/s)
  • Takeoff distance to 50 ft (15m):1,545 ft (471 m)
  • Landing distance from 50 ft (15m):1,650 ft (500 m)

See also

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Related development

Aircraft of comparable role, configuration, and era

Notes

[edit]
  1. ^These aircraft were referred to as "T337G" on theFederal Aviation Administrationtype certificate,but were given "P337" construction numbers by Cessna.

References

[edit]
  1. ^abcdWood, Derek:Jane's World Aircraft Recognition Handbook,page 471. Jane's Publishing Company, 1985.ISBN0-7106-0343-6
  2. ^abcdefPlane and Pilot:1978 Aircraft Directory,page 92. Werner & Werner Corp Publishing, 1978.ISBN0-918312-00-0
  3. ^abcdefghijklTaylor, Michael:Encyclopedia of Modern Military Aircraft;page 67; Gallery Books; 1987;ISBN0-8317-2808-6
  4. ^abcdefFitzsimons, Bernie:The Defenders - A Comprehensive Guide to the Warplanes of the USA,page 54. Gallery Books, 1988.ISBN0-8317-2181-2
  5. ^Green, William:Observers Aircraft,page 46. Frederick Warne Publishing, 1974.ISBN0-7232-1526-X
  6. ^McClellan, J Mac:Adam A500,Flying Magazinepages 52-58.Hachette Filipacchi Media U.S.,December 2007. ISSN 0015-4806
  7. ^"NTSB Identification: CEN12FA058, 14 CFR Part 91: General Aviation".NTSB. November 10, 2011.
  8. ^"Airworthiness Directive 77-08-05".Federal Aviation Administration. April 28, 1977.RetrievedOctober 24,2014.
  9. ^"CDF aviation management history".State of California.RetrievedJuly 4,2015.
  10. ^abCocks, Chris (2009).Fireforce: One Man's War in the Rhodesian Light Infantry.30° South Publishers. p. 33.ISBN978-0-9584890-9-6.
  11. ^University of MinnesotaHuman Rights Library (1999)."Armando Alejandre Jr., Carlos Costa, Mario de la Pena y Pablo Morales v. Republica de Cuba, Case 11.589, Report No. 86/99, OEA/Ser.L/V/II.106 Doc. 3 rev. at 586 (1999)".RetrievedDecember 7,2007.
  12. ^abcdefghijklmnSimpson, Roderick W. (1991).Airlife's general aviation: a guide to post-war general aviation manufacturers and their aircraft.Shrewsbury: Airlife Publ. [u.a.]ISBN978-1-85310-194-6.
  13. ^abcdefghijklmnPhillips, Edward H:Wings of Cessna, Model 120 to the Citation III,Flying Books, 1986.ISBN0911139052
  14. ^"Type Certificate Data Sheet No. A2CE".Federal Aviation Administration.RetrievedJune 10,2024.
  15. ^abcdefghijklmno"Skymaster Production"(PDF).Skymaster Owners And Pilots Association.January 14, 2005.RetrievedJune 10,2024.
  16. ^abcdefghijkl"Type Certificate Data Sheet No. A6CE".Federal Aviation Administration.RetrievedJune 10,2024.
  17. ^abcdef"Type Certificate Data Sheet No. A23EU".Federal Aviation Administration.RetrievedJune 10,2024.
  18. ^abTaylor 1969, pp. 304–305.
  19. ^Murphy, Daryl (2006)."The Cessnas that got away".Archived fromthe originalon February 27, 2009.RetrievedDecember 22,2008.
  20. ^Mitzar, Flying Pinto?ArchivedAugust 16, 2004, at theWayback Machine
  21. ^The Spectrum SA-550Archived2009-03-14 at theWayback Machine
  22. ^Graham Warwick (October 25, 2018)."E-Fan Experience Spawns French Hybrid-Electric Startup".Aviation Week & Space Technology.
  23. ^Fontanellaz, Cooper & Matos 2020,p. 13
  24. ^Flight International16–22 November 2004, p. 47.
  25. ^Flight International16–22 November 2004, p. 52.
  26. ^Mais AltoJune 2012, p. 16.
  27. ^abFlight International16–22 November 2004, p. 77.
  28. ^Aeroflight website
  29. ^Flight International16–22 November 2004, p. 45.
  30. ^Flight International16–22 November 2004, p. 56.
  31. ^Flight International16–22 November 2004, p. 62.
  32. ^Brent, W A (1988).Rhodesian Air Force – A Brief History 1947–1980.Freeworld. pp. 13–23.ISBN0620118059.
  33. ^World Air Forces – Countries"World Air Forces Countries".Archivedfrom the original on July 16, 2012.RetrievedFebruary 15,2021..
  34. ^Taylor 1969, pp. 303–304.
  • Fontanellaz, Adrien; Cooper, Tom; Matos, Jose Augusto (2020).War of Intervention in Angola, Volume 3: Angolan and Cuban Air Forces, 1975-1985.Warwick, UK: Helion & Company Publishing.ISBN978-1-913118-61-7.
  • Taylor, John W. R.Jane's All The World's Aircraft 1969–70.London: Sampson Low, Marston & Company, 1969.ISBN0-354-00051-9.
  • "World Air Forces 2004".Flight International,16–22 November 2004. pp. 41–100.
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