Boeing C-97 Stratofreighter

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 3 prototype XC-97s flew on 9 November 1944 (none saw combat), and the first of 6 service-test YC-97s flew on 11 March 1947. All these (9) 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 gunners position blanked off. The first of 3 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.[1][2] 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).

C-97 Stratofreighter
C-97 stratofreighter 041116-F-9999R-002
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
Developed from Boeing B-29 Superfortress
Boeing B-50 Superfortress
Variants Boeing KC-97 Stratofreighter
Boeing 377 Stratocruiser
Aero Spacelines Pregnant Guppy
Aero Spacelines Super Guppy
Aero Spacelines Mini Guppy

Design and development

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.[3] 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.[4]

Boeing YC-97 (45-59590) (4641652679)
YC-97 Stratofreighter with the shorter fin and smaller engines of the B-29 in 1947

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 (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.[3]

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 which 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 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.[5]

Operational history

The C-97 entered service in 1947, during a period of rapid development of heavy transport aircraft. Only 77 were built before the 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 1949–1978. 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 KC-135 in 1957. Many KC-97s were later refitted as C-97G transports and equipped several squadrons of the US 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.[6]

Boeing C-97G 0-30349 Minn ANG DM 22.04.71
Boeing KC-97G Stratofreighter of the Minnesota Air National Guard in 1971 after service as part of Military Airlift Command

Only one C-97 is still airworthy at the present day,(s/n 52-2718, named "Angel of Deliverance") operated by the Berlin Airlift Historical Foundation. It is painted as YC-97A 45-59595, the sole 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.[7] 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.[7] 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.[8][9]


military designation of the prototype Boeing 367, three built.
cargo transport, six built.
109th Air Transport Squadron Boeing C-97A Stratofreighter 49-2607
C-97A Stratofreighter 49-2607 of Minnesota Air National Guard (1960)
troop carrier, three built.
fitted with 80 airliner-style seats, later redesignated C-97B, in 1954 became C-97D, retired to MASDC 15 December 1969.[10]
transport, 50 built.
Three C-97As were converted into aerial refueling tankers with rear loading door removed and a flight refueling boom added. After the design was proven, they were converted back into the standard C-97A.
Second production version, 14 built; those used as medical evacuation transports during the Korean War were designated MC-97C.[11]
staff transport and flying command post conversions, three C-97As converted.[12]
KC-97Es converted to transports.
aerial refueling tankers with rear loading doors permanently closed; 60 built.
KC-97Fs converted to transports.
3800hp R-4360-59B engines and minor changes; 159 built.
135 KC-97Gs converted to transports.
ELINT conversion of three KC-97Gs. 53–106 was operated by the CIA for covert ELINT operations in the West Berlin Air Corridor.
dual-role aerial refueling tankers/cargo transportation aircraft. KC-97G models carried underwing fuel tanks; 592 built.
Five KC-97Gs were used as ground instruction airframes.
One aircraft was modified to test the underwing General Electric J47-GE-23 jet engines, and was later designated KC-97L.
KC-97Gs converted for search and rescue operations; 22 converted.
A YC-97J, an experimental turboprop-powered variant, in flight
One KC-97F was experimentally converted into a probe-and-drogue refueling aircraft.
KC-97G conversion with four 5,700 hp (4,250 kW) Pratt & Whitney YT34-P-5 turboprops, two converted. Originally designated YC-137.[13]
27 KC-97Gs converted to troop transports.[14]
81 KC-97Gs modified with two J47 turbojet engines on underwing pylons.


Military operators

 United States

U.S. Air Force units

The following Air Force wing organizations flew the various C-97 models at some time during their existence:[15]

Air National Guard

Boeing C-97G N227AR FAR LGB 13.10.73 edited-3
Boeing C-97G of the Foundation for Airborne Relief at Long Beach Airport, California, in 1973

Civil operators

Accidents and incidents

  • 22 May 1947 – USAF XC-97 43-27472 crashed in a wheat field near Wright-Patterson Air Force Base and caught fire, killing five of seven crew on board.[17]
  • 6 June 1951 – USAF C-97A 48-0398 crashed near Kelly Air Force Base due to a possible asymmetric flap extension on takeoff, killing all nine crew on board.[18]
  • 15 October 1951 – After taking off from Lajes Field, Azores, USAF C-97A 49-2602 of the Military Air Transport Service went missing on a flight back to Westover Air Force Base, Massachusetts. The aircraft was piloted by Captain John Francis Dailey, Jr. and had a crew of 11. A total of 50 aircraft and ships searched the intended route but no trace of the aircraft or crew was ever found.[19]
  • 22 October 1951 – USAF C-97A 48-0413 crashed and burned next to a runway at Kelly AFB, killing four of six on board.[20]
  • 27 June 1954 – USAF KC-97G 52-2654 crashed into Box Springs Mountain, killing all 14 on board. The aircraft was diverting to Norton AFB due to poor weather at its destination, March AFB.[21]
  • 4 May 1955 – USAF KC-97G 53-0110 was flying in formation when it crashed into the Atlantic 90 mi off Iceland due to loss of control caused by an engine fire, killing all nine on board.[22]
  • 6 July 1956 – USAF KC-97E 51-0220 crashed in a wooded area 45 mi northeast of Goose Bay, Canada after reporting an engine fire, killing all six on board.[23]
  • 22 January 1957 – USAF KC-97G 53-0222 of the 384th Air Refueling Squadron crashed in the Adirondack mountain foothills while on a refueling training mission, killing all seven on board.[24]
  • 22 March 1957 – USAF C-97C 50-0702 en route to Tokyo went missing over the Pacific Ocean, with 10 crew and 57 passengers on board. It is the deadliest incident ever involving the C-97.[25]
  • 18 July 1957 – USAF KC-97G 52-2737 crashed in Lake Champlain due to double engine failure, killing six of eight on board.[26]
  • 29 October 1957 – USAF KC-97G 52-2711 struck a mountain in poor visibility 35 mi north of Flagstaff, Arizona during a survey flight, killing all 16 on board.[27]
  • 19 January 1958 – USAF C-97A 49-2597 en route to Wake Island from Honolulu went missing over the Pacific Ocean with seven crew on board.[28]
  • 22 July 1959 – USAF KC-97G 52-2703 of the 509th Air Refueling Squadron crashed near Andover, New Hampshire due to an in-flight fire while on a night time training mission, killing all seven on board. The fire was caused by a turbocharger bearing failure which then caused a fuel leak.[29]
  • 30 March 1960 – USAF KC-97F 51-0363 ditched in the Atlantic off Florida in high winds, killing two of 14 on board.[30]
  • 27 June 1960 – USAF KC-97G 52-2738 of the 380th Air Refueling Squadron was one of two KC-97G's in crew T-51 which were to refuel a B-47 under simulated combat conditions. 52-2738 was about to connect with the B-47 when the number one engine caught fire. The aircraft turned left and went into a spin. The outer portion of the left wing, weakened by the fire, separated and the aircraft crashed out of control into a mountain near Newry, Maine, killing all five on board.[31]
  • 29 June 1964 – USAF HC-97G 52-2773, along with USAF HC-54D 42-72590, were performing pararescue training and photography missions for the NASA Gemini program when the HC-54 banked to the right, colliding with the HC-97 and shearing off the wing and tail section; both aircraft crashed in the water off Bermuda, killing 17 on board both aircraft; seven survived after they jumped before the aircraft collided. The cause was probably incapacitation of the HC-54 pilot.[32]
  • 19 December 1964 – USAF KC-97G 52-907 ran off the runway at Ernest Harmon AFB after the pilot landed too far down the runway, killing all five on board. The pilot attempted to abort the landing, but the aircraft struck approach lights and crashed into a pond.[33]
  • 19 January 1969 – Wisconsin Air National Guard KC-97L 52-0904 crashed short of the runway at General Mitchell Airport, killing four of 11 on board.[34]
  • 26 September 1969 – A Nordchurchaid C-97G, (N52676), struck trees and crashed while on final approach to Uli Airstrip, killing all five on board.[35]
  • 30 November 1970 – Israeli Air Force KC-97G 4X-FPS/037 was being towed across runway 30 at Lod International Airport when it was struck by a TWA Boeing 707; both aircraft caught fire. Two people on the ground died.[36]
  • 17 September 1971 – Israeli Air Force KC-97G 4X-FPR/033 was shot down by Egyptian missiles after penetrating Egyptian airspace along the Suez Canal, killing seven of eight on board.[37]
  • 30 July 1987 – After taking off, a C-97G (HI-481) operated by Belize Air International (a cargo airline) crashed onto the Mexico City-Toluca highway after the cargo shifted, killing 5 of 12 on board and 44 on the ground.[38]

Surviving aircraft

C-97G 52-2764 parked in front of the Don Q Inn just north of Dodgeville, WI on Highway 23.


On display

United States

On display

Specifications (C-97)

Data from Boeing C-97 Stratofreighter[49][50][51]

General characteristics


See also

Related development

Aircraft of comparable role, configuration and era

Related lists


  1. ^ Bach 1996, p. 7
  2. ^ Bowers 1989, pp. 353–359.
  3. ^ a b Swanborough and Bowers 1989, p. 125.
  4. ^ Bowers 1989, p. 353.
  5. ^ Bach 1996, p. 40
  6. ^ "ASN Aviation Safety Database." Aviation Safety Network, Flight Safety Foundation. Retrieved: 27 April 2009.
  7. ^ a b Archer Aeroplane May 2017, p. 94.
  8. ^ Rubinstein and Goldman 1979, p. 89.
  9. ^ "East of the Suez". Israeli Air Force official website. Retrieved 19 February 2013.
  10. ^ Bowers 1989, p. 357.
  11. ^ Bowers 1989, p. 358.
  12. ^ Bowers 1989, p. 362.
  13. ^
  14. ^ Bowers 1989, p. 364.
  15. ^ Ravenstein, Charles A., ed. Air Force Combat Wings: Lineage and Honors Histories, 1947–1977. Washington, D.C.: United States Air Force Historical Research Center, Office of Air Force History, 1984. ISBN 0-912799-12-9.
  16. ^ "A Mission of History, Education and Remembrance." Spirit of Freedom, 2011. Retrieved: 21 October 2011.
  17. ^ Accident description for 43-27472 at the Aviation Safety Network. Retrieved on 26 January 2013.
  18. ^ Accident description for 48-0398 at the Aviation Safety Network. Retrieved on 26 January 2013.
  19. ^ Union News, Springfield, Massachusetts, 16 October 1951.
  20. ^ Accident description for 48-0413 at the Aviation Safety Network. Retrieved on 26 January 2013.
  21. ^ Accident description for 52-2654 at the Aviation Safety Network. Retrieved on 2015-06-30.
  22. ^ Accident description for 53-0110 at the Aviation Safety Network. Retrieved on 2015-06-30.
  23. ^ Accident description for 51-0220 at the Aviation Safety Network. Retrieved on 2015-06-30.
  24. ^ Accident description for 52-0222 at the Aviation Safety Network. Retrieved on 2015-06-30.
  25. ^ Accident description for 50-0702 at the Aviation Safety Network. Retrieved on 26 January 2013.
  26. ^ Accident description for 52-2737 at the Aviation Safety Network. Retrieved on 2015-06-30.
  27. ^ Accident description for 52-2711 at the Aviation Safety Network. Retrieved on 2015-06-30.
  28. ^ Accident description for 49-2597 at the Aviation Safety Network. Retrieved on 26 January 2013.
  29. ^ Accident description for 52-2703 at the Aviation Safety Network. Retrieved on 2015-06-30.
  30. ^ Accident description for 51-0363 at the Aviation Safety Network. Retrieved on 2015-06-30.
  31. ^ Accident description for 52-2738 at the Aviation Safety Network. Retrieved on 2015-06-30.
  32. ^ Accident description for 52-2773 at the Aviation Safety Network. Retrieved on 2015-06-30.
  33. ^ Accident description for 52-907 at the Aviation Safety Network. Retrieved on 2015-06-30.
  34. ^ Accident description for 52-0904 at the Aviation Safety Network. Retrieved on 2025-06-30.
  35. ^ Accident description for N52676 at the Aviation Safety Network. Retrieved on 26 January 2013.
  36. ^ Accident description for 4X-FPS/037 at the Aviation Safety Network. Retrieved on 2015-06-30.
  37. ^ Accident description for 4X-FPR/033 at the Aviation Safety Network. Retrieved on 2015-06-30.
  38. ^ "Accident Report: Boeing C-97 Stratofreighter G, 30 July 1987." Aviation Safety Network. Retrieved: 21 October 2011.
  39. ^ "C-97K Stratofreighter/AF Serial No. 52-2799." Retrieved: 8 November 2011.
  40. ^ "FAA Registry: N117GA." Retrieved: 20 July 2016.
  41. ^ "C-97G Stratofreighter/AF Serial No. 52-2718 'Angel of Deliverance'." Retrieved: 13 November 2010.
  42. ^ "USAF Serial Number Search (52-898)". Retrieved 2018-02-14.
  43. ^ "Aerial Visuals Airframe Dossier (52-0898)". Retrieved 2018-02-14.
  44. ^ "Volk Field Air National Guard Base", Wikipedia, 2018-10-31, retrieved 2019-06-18
  45. ^ "C-97G Stratofreighter/AF Serial No. 52-2626." Retrieved: 20 July 2016.
  46. ^
  47. ^ "C-97G Stratofreighter/AF Serial No. 52-2764." Don Q Inn. Retrieved: 20 July 2016.
  48. ^ [1]
  49. ^ "Boeing – History – C-97 Stratofreighter." Archived 2010-02-07 at the Wayback Machine Boeing. Retrieved: 27 April 2009.
  50. ^ Hansen, Dave. "Boeing C-97 Stratofreighter." Warbird Alley, 27 April 2009.
  51. ^ "C-97 Stratofreighter Specifications.", 27 April 2009.
  52. ^ Bridgman 1952, p. 184.
  • Archer, Bob. "Database: Boeing C-97". Aeroplane, Vol. 45, No. 5, May 2017. pp. 81–97. ISSN 0143-7240.
  • Bach, Martin. Boeing 367 Stratofreighter, Boeing 377 Stratocruiser, Aero Spacelines Guppies. Allershausen: NARA Verlag, 1996. ISBN 3-925671-18-8.
  • Bowers, Peter M. Boeing Aircraft since 1916. London: Putnam Aeronautical Books, 1989, ISBN 0-85177-804-6.
  • Bridgman, Leonard. Jane's All The World's Aircraft 1952–53. London: Sampson Low, Marston & Company, 1952.
  • Rubinstein, Murray and Richard Goldman. The Israeli Air Force Story London: Arms & Armour Press, 1979. ISBN 0-85368-462-6.
  • Swanborough, Gordon and Peter M Bowers: United States Military Aircraft since 1909. London: Putnam Aeronautical Books, 1989, ISBN 0-85177-816-X.

External links

133d Operations Group

The 133rd Operations Group is the flying component of the Minnesota Air National Guard's 133d Airlift Wing, stationed at Minneapolis–Saint Paul Joint Air Reserve Station, Minnesota. If activated to federal service, the group is gained by Air Mobility Command of the United States Air Force.

The group was first activated as the 367th Fighter Group, an Army Air Forces unit. The group trained in the western United States with Bell P-39 Airacobras. The 367th moved to England in the spring of 1944, where it became part of IX Fighter Command (later XIX Tactical Air Command) and converted to Lockheed P-38 Lightnings. The group engaged in combat with Lightnings, and later with Republic P-47 Thunderbolts, in the European Theater of Operations until VE Day, earning two Distinguished Unit Citations and the Belgian Fourragere for its actions. It returned to the United States in the fall of 1945 and was inactivated on 7 November 1945.

In May 1946, the group was allotted to the National Guard and renumbered as the 133d Fighter Group. It trained with North American P-51 Mustangs. In 1951 it was mobilized for the Korean War and served in an air defense role until inactivating in February 1952 in a reorganization of Air Defense Command.

The group was returned to the Minnesota Air National Guard in December 1952. It was an air defense fighter unit until 1960, when it converted to the Boeing C-97 Stratofreighter and the airlift mission. It was called to active duty during the Berlin Crisis of 1961. The 133d replaced its C-97s with Lockheed C-130 Hercules aircraft in 1971. It was inactivated in early 1975, when its component units were assigned directly to its parent 133d Tactical Airlift Wing. It was reactivated in 1994 and resumed its role as the operational component of the 133d Wing.

164th Airlift Wing

The 164th Airlift Wing is a unit of the Tennessee Air National Guard, stationed at Memphis Air National Guard Base, Tennessee. If activated to federal service in the United States Air Force, the 164th is gained by Air Mobility Command.

The wing has been an airlift unit since it was established as the 164th Air Transport Group in 1961, and has flown a variety of strategic and tactical airlift aircraft. After 34 years as a group, it was expanded to become a wing in 1995.

1707th Air Transport Wing

The 1707th Air Transport Wing is a discontinued United States Air Force unit. It was last assigned to Military Air Transport Service (MATS) at Tinker Air Force Base, Oklahoma. It was discontinued on 8 January 1966, when MATS replaced its Major Command controlled (MAJCON) wings with Air Force controlled (AFCON) wings when MATS was redesignated as Military Airlift Command. The mission, personnel and equipment of the wing were transferred to the 443d Military Airlift Wing, which was simultaneously activated.

180th Airlift Squadron

The 180th Airlift Squadron (180 AS) is a unit of the Missouri Air National Guard 139th Airlift Wing located at Rosecrans Air National Guard Base, St. Joseph, Missouri. The 180th is equipped with the C-130H2 Hercules.

48th Air Transport Squadron

The 48th Air Transport Squadron is an inactive United States Air Force unit. Its last was assigned to the 1502d Air Transport Wing, Military Air Transport Service, stationed at Hickam Air Force Base, Hawaii. It was inactivated on 25 June 1965.

Boeing KC-97 Stratofreighter

The Boeing KC-97 Stratofreighter is a United States strategic tanker aircraft based on the Boeing C-97 Stratofreighter. It was succeeded by the Boeing KC-135 Stratotanker.

Boeing Renton Factory

The Boeing Company's Renton, Washington Factory is a facility where Boeing 737 Next Generation and Boeing 737 MAX airliners are built. Current production includes the 737-700, 737-800, 737-900ER, 737 MAX 7, 737 MAX 8, 737 MAX 9, and 737 MAX 10 models. The floor space covered is 1.1 million square feet (102,000 square meters).The factory lies adjacent to Renton Municipal Airport.

Double-deck aircraft

A double-deck aircraft has two decks for passengers; the second deck may be only a partial deck, and may be above or below the main deck. Most commercial aircraft have one passenger deck and one cargo deck for luggage and ULD containers, but only a few have two decks for passengers, typically above a third deck for cargo.

Boeing military aircraft
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Army/Air Force sequence
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