|Role||Military transport aircraft|
|First flight||9 November 1944|
|Primary users||United States Air Force|
Israeli Air Force
|Number built||77 (total of 888 in all variants)|
|Developed from||Boeing B-29 Superfortress|
Boeing B-50 Superfortress
The Boeing C-97 Stratofreighter was a long-range heavy military cargo aircraft developed from the B-29 and B-50 bombers. Design work began in 1942, the first of three prototype XC-97s flew on 9 November 1944 (none saw combat), and the first of six service-test YC-97s flew on 11 March 1947. All nine were based on the 24ST alloy structure and Wright R-3350 engines of the B-29, but with a larger-diameter fuselage upper lobe (making a figure of eight or "double-bubble" section) and they had the B-29 vertical tail with the gunner's position blanked off. The first of three heavily revised YC-97A incorporating the re-engineered wing ( higher strength 75ST alloy), taller vertical tail and larger Pratt and Whitney R-4360 engines of the B-50 bomber, flew on 28 January 1948 and was the basis of the subsequent sole YC-97B, all production C-97s, KC-97s and civilian Stratocruiser aircraft. Between 1944 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).
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 was built before the death of Boeing president Philip G. Johnson. 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 takeoffs 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.
The civilian derivative of the C-97 was the Boeing 377 Stratocruiser, a very luxurious transoceanic airliner that featured a lower deck lounge and could be fitted with sleeper cabins. The first Stratocruiser flew on July 8, 1947. Only 56 were built.
The C-97 entered service in 1947, during a period of rapid development of heavy transport aircraft. Only 77 were built before the Douglas C-124 Globemaster II was delivered in 1950, with nearly twice the payload capacity of the C-97. The USAF Strategic Air Command operated C-97 Stratofreighters from 1949 to 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. The KC-97 began to be phased out with the introduction of the Boeing KC-135 Stratotanker in 1957. Many KC-97s were later refitted as C-97G transports and equipped several squadrons of the U.S. Air National Guard.
One YC-97A (45–59595) was used in the Berlin Airlift during April 1949, operating for the 1st Strategic Support Squadron. It suffered a landing gear accident at Gatow 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.
Only one C-97 is still airworthy at the present day,[when?] (S/N 52-2718, named "Angel of Deliverance") operated by the Berlin Airlift Historical Foundation. It is painted as YC-97A 45-59595, the only C-97 to participate in the Berlin Airlift.
The Israelis turned to Stratocruisers and KC-97s when they could not buy the preferred C-130. They adapted Boeing 377 Stratocruiser airliners into transports, including many using C-97 tail sections including the loading ramps. 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.
The following Air Force wing organizations flew the various C-97 models at some time during their existence:
Data from Boeing C-97 Stratofreighter
Aircraft of comparable role, configuration, and era