Boeing C-97 Stratofreighter

The Boeing C-97 Stratofreighter is a long-range heavy military cargo aircraft developed from the B-29 and B-50 bombers. Design work began in 1942, with the prototype's first flight being on 9 November 1944, and the first production aircraft entered service in 1947. Between 1947 and 1958, 888 C-97s in several versions were built, 811 being KC-97 tankers. C-97s served in the Berlin Airlift, the Korean War, and the Vietnam War. Some aircraft served as flying command posts for the Strategic Air Command, while others were modified for use in Aerospace Rescue and Recovery Squadrons (ARRS).

Boeing C-97 Stratofreighter
Class Aircraft
Type Transport
Manufacturer Boeing
Origin United States of America
Country Name Origin Year
United States of America 1945
Country Name Operational Year Retirement Year
Israel View
Israel View
United States of America 1947 1978 View
ManufacturerName Production From Production To Quantity
Boeing 60 View

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 which were essentially the same as those of the B-29 Superfortress with the tail, wing, and engine layout being nearly identical. It was built before the death of Boeing president Philip G. Johnson. It can be easily distinguished from the 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.

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 a retractable ramp could be used to drive in cargo. However, unlike the later Lockheed C-130 Hercules, it was not designed as a combat transport which could deliver directly to primitive forward bases using relatively short takeoffs and landings. The rear ramp could not be used in flight for air drops.

On 9 January 1945, the first prototype, piloted by Major Curtin L. Reinhardt, flew from Seattle to Washington, DC in 6 hours 4 minutes, an average speed of 383 mph (616 km/h) with 20,000 lb (9,100 kg) of cargo, which was for its time 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 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.

The civilian derivative of the C-97 was the Boeing 377 Stratocruiser, a very luxurious transoceanic airliner which featured a lower deck lounge and could be fitted with sleeper cabins. The first Stratocruiser flew on July 8, 1947. Only 56 were built.

One YC-97A (45-9595) was used in the Berlin Airlift during April 1949 operating for the 1st Strategic Support Squadron. It suffered a landing gear accident at Rhein Main Air Base and by the time it was repaired, the Soviet Blockade was lifted.

C-97s evacuated casualties during the Korean War. C-97s also participated in the Biafran airlift, delivering relief materials to Uli airstrip in Biafra during the Nigerian Civil War. Flying under the cover of darkness and at treetop level to evade radar, at least two C-97s were lost.

The USAF Strategic Air Command operated C-97 Stratofreighters from 1949-1978. Early in its service life, it served as an airborne alternative SAC command post. While only 77 C-97 transports were built, 811 were built as KC-97 Stratofreighters for inflight refueling. Many KC-97s were later refitted as C-97G transports and equipped several squadrons of the US Air National Guard.

Two C-97s are still airworthy at the present day, one (s/n 52-2718, named "Angel of Deliverance") operated as a privately owned warbird, the other operated as a fire bomber in the United States.

The Israelis turned to Stratocruisers and KC-97s when they could not buy the highly regarded C-130. They adapted Boeing 377 Stratocruiser airliners into transports, including many using C-97 tail sections including the loading ramp. Others were adapted with swiveling tails and refueling pods. One Israeli C-97 was downed by an Egyptian SA-2 Guideline missile on 17 September 1971, while flying as an electronic counter-measures platform some 12 miles from the Suez Canal.

Role Military transport aircraft
Manufacturer Boeing
First flight 9 November 1944
Introduction 1947
Retired 1978
Primary users United States Air Force
Israeli Air Force
Produced 1944–1952
Number built 77 (total of 888 in all variants)
Unit cost $1,205,000
Developed from Boeing B-29 Superfortress
Boeing B-50 Superfortress
Variants Boeing KC-97 Stratofreighter
Boeing 377 Stratocruiser
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Aero Spacelines Super Guppy
Aero Spacelines Mini Guppy

General characteristics

  • Crew: 4:
  • Length: 110 ft 4 in (33.7 m)
  • Wingspan: 141 ft 3 in (43.1 m)
  • Height: 38 ft 3 in (11.7 m)
  • Wing area: 1,734 ft (161.1 m)
  • Empty weight: 82,500 lb (37,410 kg)
  • Loaded weight: 120,000 lb (54,420 kg)
  • Max takeoff weight: 175,000 lb (79,370 kg)
  • Powerplant: 4 x Pratt & Whitney R-4360 Wasp Major radial engines, 3,500 hp (2,610 kW) each

Performance

  • Maximum speed: 375 mph (603 km/h)
  • Cruise speed: 244 mph (212 knots, 393 km/h)
  • Ferry range: 5,000 nm (5,760 mi, 9,270 km)
  • Service ceiling 35,000 ft (10,670 m)
  • Wing loading: 69.2 lb/ft (337.8 kg/m)
  • Power/mass: 0.117 hp/lb (192 W/kg)

End notes