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
Equipment:
Body: Medium radio transmitter and receiver,
navigation instruments, IFF, searchlight, two stretcher pallets (carried
externally).
Statistics:
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.
Design
Notes:
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.
Variants:
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