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 military
O-2 versions.[1] Production in America ended in 1982, but was continued by
Reims in France, with the FTB337
STOL and the military FTMA Milirole.[4]
Design
The Skymaster handles differently from a conventional twin-engine aircraft, primarily in that if an engine fails, the plane will not
yaw toward 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-out
minimum 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 while
taxiing on 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 Directive 77-08-05 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 rear
pusher propeller slicing through turbulent air from the front propeller and over the airframe while its front
tractor propeller addresses undisturbed air.[2]
During the
Rhodesian Bush War, the Reims-Cessna FTB 337G 'Lynx' was the main light attack aircraft used by
Rhodesian Security Forces during Fire Force
counterinsurgencyair assault missions, which began in 1974. The Lynxes were armed with twin Browning .303 machine guns mounted above the wing and 37mm
SNEB rockets, locally made Mini "Alpha" Bombs (
cluster bombs), Mini "Golf" Bombs (450 lb (200 kg) blast and shrapnel bomb) and Frantan (a napalm variant carried in frangible drop tanks) bombs.[10]
From 1991 until 2001 the
Cuban exile group Hermanos al Rescate (Brothers to the Rescue) used Skymasters, among other aircraft, to fly
search and rescue missions over the
Florida Straits looking for rafters attempting to cross the straits to
defect from Cuba, and when they found them, dropped life-saving supplies to them. Rescues were coordinated with the
US 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 were
shot down by the
Cuban Air Force over international waters. Both aircraft were downed by a
MiG-29, while a second jet fighter, a
MiG-23, orbited nearby.[11]
Variants
Cessna
327 Baby Skymaster - reduced scale four-seat version of the 337, with
cantilever wings replacing the 336/337 strut-braced configuration. It first flew in December 1967. One
prototype was built before the project was cancelled in 1968 due to lack of commercial interest in the design. The prototype was delivered to
NASA to serve as a full-scale model for
wind tunnel testing. It was used in a joint Langley Research Center and Cessna project on noise reduction and the use of ducted versus free propellers.[12]
336 Skymaster - production version powered by two 195 hp (145 kW) Continental IO-360-A engines, 195 built.
337 Super Skymaster - 336; retractable
undercarriage, redesigned nose
cowling and new rear engine intake, and greater wing
angle of incidence, powered by two 210 hp (160 kW) Continental IO-360-C engines, 239 built.
337A Super Skymaster - 337; minor detail changes, 255 built.
T337B (1967) Turbo Super Skymaster - 337B; two Continental turbocharged fuel injected 210 hp (160 kW) engines which boosted service ceiling to 33,000 feet (10,000 m), cruise speed to 233 mph (375 km/h), and range to 1,640 miles (2,640 km)
337C Super Skymaster - 337B; new instrument panel and increased take-off gross-weight, 223 built.
337D Super Skymaster - 337C; minor detail changes, 215 built.
337E Super Skymaster - 337D; cambered wingtips and minor changes, 100 built.
O-2B: Psychological warfare version for the US Air Force (31 former civil aircraft were converted to O-2B standard).[4]
O-2T: Twin-turboprop version of O-2, with two 317 hp (236 kW)
Allison 250-B15 engines, a longer span wing and improved high lift devices.[13]
O-2TT: Improved twin turboprop forward air control aircraft, with same wing (43 ft 0 in (13.11 m) wing and engines of O-2T but with new forward fuselage with tandem seating for pilot and observer to give improved view.[4][13]
Conroy Stolifter - an extensive single-turboprop engine STOL cargo plane conversion of the Skymaster. Front engine was replaced with a
Garrett 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.
Summit Sentry - Summit Aviation of
Middletown, Delaware re-manufactured existing used 337 airframes into the militarized O2-337 which 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 the
Haitian Air Force,
Honduras,
Nicaragua,
Senegal and the
Thai Navy. The variant was still in production in 1987.[3]
Spectrum SA-550 - built by
Spectrum Aircraft Corporation of
Van 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.[15]
VoltAero is a startup company formed in September 2017 by the
CTO and test pilot of the 2014
Airbus E-Fan 1.0. The company has been established in
Royan, with support from the French
Nouvelle-Aquitaine region. It is developing a hybrid
electric aircraft testbed based on the Skymaster, which is intended to fly in late February 2019. It will be followed up by the
VoltAero Cassio prototype in 2020, a clean-sheet, all-composite design.[16]
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.[20]
Portuguese Air Force[3] (32 × FTB-337G): Purchased in 1973 to replace the force's aging
Dornier Do 27 fleet, which had been used intensively in the
Portuguese 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.
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.