# Boeing C-97 Stratofreighter
The **Boeing C-97 Stratofreighter** was a long-range, four-engine heavy military cargo aircraft developed by Boeing from its B-29 and B-50 bombers, and the basis for the KC-97, the [United States Air Force](https://www.edgepedia.org/united-states-air-force)'s first mass-produced aerial refueling tanker. Boeing designated the design Model 367. The first of three XC-97 prototypes flew on 9 November 1944, production ended in 1956, and the type served with the Air Force, Air Force Reserve, and [Air National Guard](https://www.edgepedia.org/air-national-guard) into the late 1970s.[1](https://www.aflcmc.af.mil/NEWS/Article/3935483/this-week-in-aflcmc-history-october-14-20-2024/) • [2](https://museumofaviation.org/portfolio/kc-97l-stratofreighter/)
| Key fact | Detail |
|---|---|
| Manufacturer's model | Boeing Model 367; developed from the B-29 and B-50 bombers[3](https://www.boeing.com/content/dam/boeing/boeingdotcom/history/pdf/Boeing_Products.pdf) |
| First flight | 9 November 1944 (XC-97 prototype)[1](https://www.aflcmc.af.mil/NEWS/Article/3935483/this-week-in-aflcmc-history-october-14-20-2024/) |
| Production | 890 aircraft ordered: 74 C-97 transports and 816 KC-97 tankers; last KC-97G delivered 16 November 1956[2](https://museumofaviation.org/portfolio/kc-97l-stratofreighter/) • [4](https://airandspace.si.edu/collection-objects/boeing-kc-97g-stratofreighter/nasm_A19790913000) |
| Powerplant | Four Pratt & Whitney R-4360 Wasp Major radials of 3,500 hp each[3](https://www.boeing.com/content/dam/boeing/boeingdotcom/history/pdf/Boeing_Products.pdf) |
| Performance | Top speed 375 mph, cruising speed 300 mph, range 4,300 miles, ceiling 35,000 feet[3](https://www.boeing.com/content/dam/boeing/boeingdotcom/history/pdf/Boeing_Products.pdf) |
| Cargo volume | 6,140 cubic feet of usable cargo space, more than twice the volume of any transport then flying[4](https://airandspace.si.edu/collection-objects/boeing-kc-97g-stratofreighter/nasm_A19790913000) |
| Service life | Entered service 1947; last USAF C/KC-97 retired 1973, last Reserve and Air National Guard examples 1978[5](https://vintageaviationnews.com/warbird-articles/today-in-aviation-history-first-flight-of-the-boeing-c-97-stratofreighter.html) • [2](https://museumofaviation.org/portfolio/kc-97l-stratofreighter/) |
## Design
Boeing began design studies for a transport derivative of the B-29 in 1942, and the US Army Air Forces awarded a contract for three XC-97 prototypes in January 1943. Because Boeing was concentrating on B-17 and B-29 production, the transport was a second priority, and the first prototype did not fly until 9 November 1944.[6](https://gvgoebel.nekoweb.org/av/avb29_2.html)
**The double-bubble fuselage** was the design's central feature. The B-29's circular cross-section was not practical for cargo, so Boeing engineers stacked one fuselage section on top of another in an inverted "figure 8" arrangement: the lower lobe matched the B-29 fuselage diameter, while the larger upper lobe was streamlined into it. The wing and landing gear remained those of the B-29.[4](https://airandspace.si.edu/collection-objects/boeing-kc-97g-stratofreighter/nasm_A19790913000) • [7](https://www.airandspaceforces.com/PDF/MagazineArchive/Magazine%20Documents/1997/February%201997/0297classics.pdf) The pressurized upper-deck cargo compartment was 74 feet long, with large rear clamshell doors for rapid loading of items up to 61 feet long; cargo was loaded through belly doors using a built-in ramp and a hoist.[4](https://airandspace.si.edu/collection-objects/boeing-kc-97g-stratofreighter/nasm_A19790913000) • [8](https://secure.boeingimages.com/archive/Building-the-C-97-Stratofreighter-2F3XC5QN4YD.html)
The XC-97 demonstrated the design's performance soon after its first flight: in January 1945 it flew nonstop from Seattle, Washington, to Washington, D.C., in six hours and four minutes at an average speed of 383 mph while carrying a payload of 10 tons, a transport airplane speed record.[7](https://www.airandspaceforces.com/PDF/MagazineArchive/Magazine%20Documents/1997/February%201997/0297classics.pdf) • [9](https://www.airplanes-online.com/c97-stratofreighter.htm) The C-97 was the first mass-produced transport to feature pressurization.[10](https://www.flight-manuals-online.com/product/boeing-c-97-stratofreighter/)
## Variants and production
The first of 44 C-97A production models flew on 16 June 1949, and the Military Air Transport Service received its first production C-97A on 17 October 1949.[4](https://airandspace.si.edu/collection-objects/boeing-kc-97g-stratofreighter/nasm_A19790913000) • [1](https://www.aflcmc.af.mil/NEWS/Article/3935483/this-week-in-aflcmc-history-october-14-20-2024/) Later production versions used the engines and empennage of the B-50.[10](https://www.flight-manuals-online.com/product/boeing-c-97-stratofreighter/) A tanker version, the KC-97, was introduced in 1950 using the Boeing-designed flying boom, whose operator could "fly" the boom's end into the receiving airplane; all subsequent Air Force contracts for C-97s were for tankers.[2](https://museumofaviation.org/portfolio/kc-97l-stratofreighter/) • [3](https://www.boeing.com/content/dam/boeing/boeingdotcom/history/pdf/Boeing_Products.pdf) The first of 60 production KC-97E tankers was delivered in July 1951, followed by 159 KC-97Fs and then the KC-97G, of which 592 were built; the KC-97G's internal refueling tanks allowed it to carry troops or cargo without removing the refueling equipment.[4](https://airandspace.si.edu/collection-objects/boeing-kc-97g-stratofreighter/nasm_A19790913000)
The XC-97 also served as the prototype for the commercial [Boeing 377 Stratocruiser](https://www.edgepedia.org/boeing-377-stratocruiser) airliner, of which 56 were built.[4](https://airandspace.si.edu/collection-objects/boeing-kc-97g-stratofreighter/nasm_A19790913000) • [1](https://www.aflcmc.af.mil/NEWS/Article/3935483/this-week-in-aflcmc-history-october-14-20-2024/) Other conversions included 135 KC-97Gs stripped of refueling gear as C-97G cargo aircraft, 26 C-97K passenger-configured transports, 28 HC-97Gs for air-sea search and rescue, and VC-97 VIP transports.[11](https://www.airandspaceforces.com/app/uploads/2024/09/AFmag_1974_05.pdf) • [7](https://www.airandspaceforces.com/PDF/MagazineArchive/Magazine%20Documents/1997/February%201997/0297classics.pdf)
## Operational service
**Korea.** During the [Korean War](https://www.edgepedia.org/korean-war), C-97s flew with the Military Air Transport Service, which used its C-47s, C-54s, C-97s, C-119s, and C-124s to carry 214,000 passengers and 80,000 tons of cargo across the Pacific, moving them from the United States to staging areas in Japan.[12](https://www.amcmuseum.org/history/airlift-during-the-korean-war/) Early cargo models were used extensively to bring Korean War casualties back to the US west coast from Japan, and ten pressurized C-97 transports were reconfigured and delivered as MC-97s in February 1951; the MC-97C variant could carry up to 79 casualties with a crew of four medical attendants.[7](https://www.airandspaceforces.com/PDF/MagazineArchive/Magazine%20Documents/1997/February%201997/0297classics.pdf) • [13](https://www.afhistory.af.mil/Portals/64/Books/Titles/Aeromedical%20Evacuation.pdf?ver=2017-05-16-130645-297)
**Tanker work and its limits.** The KC-97 served as the mainstay of [Strategic Air Command](https://www.edgepedia.org/strategic-air-command)'s refueling fleet, supporting the B-47 Stratojet; the 2nd Air Refueling Squadron set a record by transferring 563,270 gallons of fuel to B-47s in sixteen days in 1955.[14](https://www.sacmuseum.org/visit/exhibit/kc-97g-stratofreighter/) The piston-engine tanker was a poor match for jet bombers, however. To refuel a B-47 it had to enter a shallow dive to gain speed while the receiver flew nose-up, and the B-52 had to cruise near stall speed during refueling. The KC-97 could offload only 53,000 pounds of fuel, 21 percent of the B-52's capacity, and the bomber burned considerable fuel descending to and climbing from the tanker's altitude.[15](https://historynet.com/filling-stations-in-the-sky/) Starting in 1956, Air Force KC-97s were gradually replaced by the jet-powered KC-135.[7](https://www.airandspaceforces.com/PDF/MagazineArchive/Magazine%20Documents/1997/February%201997/0297classics.pdf)
**Air National Guard and Creek Party.** From 1964, selected aircraft were returned to tanker configuration as the KC-97L, primarily for the Air National Guard, with two [General Electric J47](https://www.edgepedia.org/general-electric-j47) jet engines added under the outer wings to increase speed and altitude.[2](https://museumofaviation.org/portfolio/kc-97l-stratofreighter/) Ten ANG tanker squadrons rotated five KC-97Ls through Rhein-Main, Germany, in Operation Creek Party, providing refueling support to United States Air Forces in Europe while SAC's KC-135s were committed to Southeast Asia. The operation, initially seen as temporary, ran from 1 May 1967 to 28 April 1977.[16](https://www.globalaviationresource.com/reports/2011/aircraft-history-boeing-c97/) The USAF retired its last C/KC-97 in 1973, but examples remained in use with the Air Force Reserve and Air National Guard as tankers or air-sea search and rescue aircraft until the last was retired in 1978.[2](https://museumofaviation.org/portfolio/kc-97l-stratofreighter/)
**Biafra.** In 1969 the United States sold C-97s at nominal cost to Joint Church Aid, the church consortium flying night relief flights into blockaded Biafra during the Nigerian civil war; the airlift cost about $4,000 per flight per aircraft, and one JCA C-97 was lost in a landing crash at Uli airfield with its crew uninjured.[17](https://history.state.gov/historicaldocuments/frus1969-76ve05p1/d66) • [18](https://www.govinfo.gov/content/pkg/GPO-CRECB-1969-pt30/pdf/GPO-CRECB-1969-pt30-3-1.pdf)
## Berlin Airlift and survivors
A single C-97 flew in the Berlin Airlift of 1948 and 1949: the YC-97A 45-59595, one of three delivered to the Air Force in March 1948, was sent to Germany for evaluation under actual airlift conditions. It arrived at Rhein-Main on 2 May 1949 and flew 23 missions, delivering 444.8 tons of cargo to Berlin, though engine problems forced an emergency landing that closed Gatow's runway for over seven hours.[19](https://www.spiritoffreedom.org/yc97a.html)
Of the 888 C-97/KC-97s built, only a handful survive. The C-97G serial 52-2718, named "Angel of Deliverance" and operated by the Berlin Airlift Historical Foundation, returned to flight on 7 November 2017 after a fifteen-year restoration and is painted in the livery of the Berlin Airlift YC-97A; it is described by the foundation as the world's only flying C-97.[5](https://vintageaviationnews.com/warbird-articles/today-in-aviation-history-first-flight-of-the-boeing-c-97-stratofreighter.html) • [20](https://www.spiritoffreedom.org/c97.html)
## Legacy
The C-97's fuselage diameter carried forward into Boeing's jet age: engineers based the 367-80 Dash 80 prototype, ancestor of the 707 and KC-135, on studies of improved Model 367 designs, and the Dash 80 had the same fuselage diameter as the KC-97, with the project name chosen partly to disguise the jet as a reengined C-97.[21](https://airandspace.si.edu/collection-objects/boeing-367-80-jet-transport/nasm_A19730272000) • [22](https://www.airandspaceforces.com/article/letters-2006-08/)
## References
1. [This Week In AFLCMC History, October 14-20, 2024, Air Force Life Cycle Management Center](https://www.aflcmc.af.mil/NEWS/Article/3935483/this-week-in-aflcmc-history-october-14-20-2024/)
2. [KC-97L Stratofreighter, Museum of Aviation Foundation](https://museumofaviation.org/portfolio/kc-97l-stratofreighter/)
3. [C-97/KC-97 Stratofreighter, Boeing historical product summary](https://www.boeing.com/content/dam/boeing/boeingdotcom/history/pdf/Boeing_Products.pdf)
4. [Boeing KC-97G Stratofreighter, National Air and Space Museum](https://airandspace.si.edu/collection-objects/boeing-kc-97g-stratofreighter/nasm_A19790913000)
5. [Today In Aviation History: First Flight of the Boeing C-97 Stratofreighter, Vintage Aviation News](https://vintageaviationnews.com/warbird-articles/today-in-aviation-history-first-flight-of-the-boeing-c-97-stratofreighter.html)
6. [Boeing B-50 & C-97, G. Goebel aircraft history](https://gvgoebel.nekoweb.org/av/avb29_2.html)
7. [Bombers: C-97 Stratofreighter, Air Force Magazine, February 1997](https://www.airandspaceforces.com/PDF/MagazineArchive/Magazine%20Documents/1997/February%201997/0297classics.pdf)
8. [Building the C-97 Stratofreighter, Boeing Images](https://secure.boeingimages.com/archive/Building-the-C-97-Stratofreighter-2F3XC5QN4YD.html)
9. [Boeing C-97 Stratofreighter and KC-97 Aerial Tanker, Airplanes Online](https://www.airplanes-online.com/c97-stratofreighter.htm)
10. [Boeing C-97 Stratofreighter, Flight Manuals Online](https://www.flight-manuals-online.com/product/boeing-c-97-stratofreighter/)
11. [Air Force Magazine, May 1974, C-97 data](https://www.airandspaceforces.com/app/uploads/2024/09/AFmag_1974_05.pdf)
12. [Airlift During the Korean War, Air Mobility Command Museum](https://www.amcmuseum.org/history/airlift-during-the-korean-war/)
13. [A History of Aeromedical Evacuation in the U.S. Air Force, Air Force History Office](https://www.afhistory.af.mil/Portals/64/Books/Titles/Aeromedical%20Evacuation.pdf?ver=2017-05-16-130645-297)
14. [KC-97G Stratofreighter, Strategic Air Command & Aerospace Museum](https://www.sacmuseum.org/visit/exhibit/kc-97g-stratofreighter/)
15. [These Airborne Filling Stations Give Aircraft the Fuel to Reach Around the Globe, HistoryNet](https://historynet.com/filling-stations-in-the-sky/)
16. [Aircraft History: Boeing C-97, Global Aviation Resource](https://www.globalaviationresource.com/reports/2011/aircraft-history-boeing-c97/)
17. [Memorandum on Joint Church Aid C-97 sales, Foreign Relations of the United States, 1969-1976, Vol. E-5, Part 1, Document 66](https://history.state.gov/historicaldocuments/frus1969-76ve05p1/d66)
18. [Congressional Record, Senate, 1969, Biafran airlift costs](https://www.govinfo.gov/content/pkg/GPO-CRECB-1969-pt30/pdf/GPO-CRECB-1969-pt30-3-1.pdf)
19. [A History of Boeing YC-97A 45-59595, Berlin Airlift Historical Foundation](https://www.spiritoffreedom.org/yc97a.html)
20. [C-97G 52-2718 "Angel of Deliverance", Berlin Airlift Historical Foundation](https://www.spiritoffreedom.org/c97.html)
21. [Boeing 367-80 Jet Transport, National Air and Space Museum](https://airandspace.si.edu/collection-objects/boeing-367-80-jet-transport/nasm_A19730272000)
22. [Letters: On Course for Tankers, Air Force Magazine, August 2006](https://www.airandspaceforces.com/article/letters-2006-08/)
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*Topic: Encyclopedia › Technology and the built world › Transport and spaceflight › Aviation › Military aviation › Military aircraft by type and era › Reconnaissance, AEW, and support aircraft › Military transport aircraft*
*Initially written Sep 17, 2026 · Reviewed: Oct 15, 2026 · Edited: Oct 15, 2026 · Last review: Oct 15, 2026*
*Copyright 2026 EdgeChat AI, a subsidiary of Biostate AI.*
License: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license