The C-97 Stratofreighter was developed towards the end of World War II by fitting an enlarged upper fuselage onto a lower fuselage and wings that were essentially the same as those of the B-29 Superfortress with the tail, wing, and engine layout being nearly identical.
It can be easily distinguished from the Boeing 377 Stratocruiser by the “beak” radome beneath the nose and by the flying boom and jet engines on later tanker models.
The prototype XC-97 was powered by the 2,200 hp (1,600 kW) Wright R-3350 engine, the same as used in the B-29.
The XC-97 took off for its first flight on November 9, 1944.
On 9 January 1945, the first prototype, piloted by Major Curtin L. Reinhardt, flew from Seattle to Washington, D.C. in 6 hours 4 minutes, an average speed of 383 mph (616 km/h) with 20,000 lb (9,100 kg) of cargo, which (at that time) was impressive for such a large aircraft.
Production models featured the 3,500 hp (2,600 kW) Pratt & Whitney Wasp Major engine, the same engine as for the B-50.
The tenth and all subsequent aircraft were fitted with the taller fin and rudder of the B-50 Superfortress.
The C-97 had clamshell doors under its tail, so that two retractable ramps could be used to drive in cargo.
However, unlike the later Lockheed C-130 Hercules, it was not designed as a combat transport that could deliver directly to primitive forward bases using relatively short take-offs and landings.
The two rear ramps could not be used in flight, but removed, the C-97 could be used for air drops.
The C-97 had a useful payload of 35,000 lb (16,000 kg) and could carry two normal trucks, towed artillery, or light tracked vehicles such as the M56 Scorpion.
The C-97 was also the first mass-produced air transport to feature cabin pressurization, which made long range missions somewhat more comfortable for its crew and passengers.
Variants
XC-97
Military designation of the prototype Boeing 367.
YC-97
Cargo transport.
YC-97A
Troop carrier.
YC-97B
Fitted with 80 airliner-style seats, later redesignated C-97B, in 1954 became C-97D, retired to MASDC 15 December 1969.
C-97A
transport.
KC-97A
Three C-97As were converted into aerial refuelling tankers with rear loading door removed and a flight refuelling boom added.
After the design was proven, they were converted back into the standard C-97A.
C-97C
Second production version, 14 built, those used as medical evacuation transports during the Korean War were designated MC-97C.
VC-97D
staff transport and flying command post conversions, three C-97As converted.
C-97E
KC-97Es converted to transports.
KC-97E
Aerial refuelling tankers with rear loading doors permanently closed.
C-97F
KC-97Fs converted to transports.
KC-97F
3800hp R-4360-59B engines and minor changes.
C-97G
135 KC-97Gs converted to transports.
EC-97G
ELINT conversion of three KC-97Gs.
53–106 was operated by the CIA for covert ELINT operations in the West Berlin Air Corridor.
KC-97G
Dual role aerial refuelling tankers / cargo transportation aircraft.
KC-97G models carried under wing fuel tanks.
GKC-97G
Five KC-97Gs were used as ground instruction airframes.
JKC-97G
One aircraft was modified to test the under wing General Electric J47-GE-23 jet engines, and was later designated KC-97L.
HC-97G
KC-97Gs converted for search and rescue operations.
KC-97H
One KC-97F was experimentally converted into a probe-and-drogue refueling aircraft.
YC-97J
KC-97G conversion with four 5,700 hp (4,250 kW) Pratt & Whitney YT34-P-5 turboprops, two converted.
Originally designated YC-137.
C-97K
27 KC-97Gs converted to troop transports.
KC-97L
81 KC-97Gs modified with two J47 turbojet engines on under wing pylons.
Specifications
C-97
Crew
5–6
Capacity
134 troops
or
69 stretchers
Or
Refuelling boom
(Three KC-97A aircraft only)
Length
110 ft 4 in (33.63 m)
Wingspan
141 ft 3 in (43.05 m)
Height
38 ft 3 in (11.66 m)
Wing area
1,734 sq ft (161.1 m2)
Airfoil
Root
Boeing 117 (22%)
Tip
Boeing 117 (9%)
Empty weight
82,500 lb (37,421 kg)
Gross weight
120,000 lb (54,431 kg)
Max take-off weight
175,000 lb (79,379 kg)
Powerplant
4 × Pratt & Whitney R-4360B Wasp Major 28-cylinder air-cooled radial piston engines,
3,500 hp (2,600 kW) each
Propellers
4-bladed Hamilton Standard constant-speed fully feathering propellers
