Bell H-13 Sioux (Model 47) Helicopter
The prototype for the Bell Model 47 helicopter first flew on December 8th, 1945. By March 1946, the aircraft had been awarded full certification as a civilian aircraft, a first for a helicopter anywhere in the world. The type remained in production until 1973, and was used by civilians, the U.S. Army, the U.S. Navy, and the armed forces of 39 other countries. It became a recognizable icon as the M*A*S*H ambulance helicopter (officially designated the H-13C) in the movie and television series. The H-13C was the result of a 1952 conversion of 15 H-13Bs to carry two litters externally.
The H-13C burns 6 gallons of aviation fuel per hour of routine usage. A full load of fuel costs $5.80.
Subassemblies: Small Helicopter chassis +2; Rotor -1, two fixed skids -1.
Powertrain: 117-kW Aerial HP gasoline engine with 117-kW Helicopter transmission and 29-gallon standard fuel tank [Body], 4,000-kWs battery.
Occ.: 2 CS Body, 2 PS on external pallets.
Cargo: 1.5 Body.
Armor F RL B T U
Body: 3/5 3/5 3/5 3/5 3/5
Rotor: 3/10 3/10 3/10 3/10 3/10
Wheels: 3/5 3/5 3/5 3/5 3/5
Body: Medium radio transmitter and receiver, navigation instruments, IFF, searchlight, two stretcher pallets (carried externally).
Size: 31'x?'x9' Payload: 0.49 tons Lwt.: 0.99 tons
Volume: 72 Maint.: 127 hours Cost: $2,470
HT: 11. HPs: 56 Body, 16 Rotor, 3 each Skid.
aSpeed: 85 aAccel: 2 aDecel: 6 aMR: 2 aSR: 1
Stall Speed: 0 mph.
Historical data and design requirements created a paradox between engine output, historical loaded weight, and design loaded weight. Sources often did not specify which variant of the H-13 was under consideration for the data listed, and historical loaded weights that were found were always in excess of the 1,170 lb. design maximum required by the historical 117-kW engine (or even a historical variant, see below) found in the H-13C. One source did quote a 210-kW engine; this may have served better in the design, despite historical inaccuracy. To lower weight, the Open Frame Armor rule from p. VE23 was applied to lower chassis weight (and cost) by 1/5. Design loaded weight is 25% lighter than historical loaded weight, but still in excess of the powertrains's lifting capacity. Calculations were therefore made using the design loaded weight of 1,988 lbs. Fuel capacity is 30 gallons but the design purchases the historical 29 gallons. Design aSpeed was 106 mph, and was reduced 20% to the historical value. Since the medevac version was modeled, no consideration was given to weaponry, but some models carried two .30-cal M37C machine guns, two 7.62mm M60C machine guns, or 8-tube 2.75" FFARs.
Dozens of variants exist for the Model 47, given its wide use in both civilian and military markets over the course of three decades. The prominent U.S. Army types used until 1962 include:
The H-13B (1948) was the original version accepted by the U.S. Army and designated "Sioux." 65 were built.
The H-13D was similar to the -C.
The H-13E was a 3-seat, dual-control trainer model.
The H-13G introduced a small elevator.
The H-13H upgraded the engines to 186-kW.
The H-13J featured a 179-kW engine.
The H-13K had a larger diameter main rotor and a 168-kW engine.
From the Aerodrome for GURPS
© 2008 by Jim Antonicic