Boeing KC-97 Stratofreighter

KC-97 Stratofreighter
KC-97L in Ohio Air National Guard markings
Role Strategic tanker
Manufacturer Boeing
Introduction July 14, 1951[1][2]
Retired June 1978[3]
Primary users United States Air Force
Spanish Air Force
Produced 19511956[4][5]
Number built 811
Developed from Boeing C-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.

Design and development

The KC-97 Stratofreighter was an aerial refueling tanker variant of the C-97 Stratofreighter (which was itself based on the Boeing B-29 Superfortress), greatly modified with all the necessary tanks, plumbing, and "flying boom." The cavernous upper deck was capable of accommodating oversize cargo accessed through a very large right-side door. In addition, transferrable jet fuel was contained in tanks on the lower deck (G-L models). Both decks were heated and pressurized for high altitude operations.

Note: Occasionally the KC-97 has been quoted as "Stratotanker". However, all reputable sources refer to the KC-97 as Stratofreighter, not -tanker. This includes both Boeing and the USAF themselves.[6][7]

Operational history

Two USAF A-7 Corsair IIs refueling from a KC-97.

The USAF began operating the KC-97 in 1950. It purchased a total of 811 KC-97s from Boeing,[5][8][9] as opposed to only 74 of the C-97 cargo version.[10][11][12] The KC-97 carried aviation gasoline for its own piston engines but it carried jet fuel for its refueling mission, this required an independent system for each type of fuel. However, it was able to offload its aviation gas to a receiver in an emergency in a procedure known as a "SAVE".

These tankers were vitally important to the world-wide Boeing B-47 Stratojet strategic operations. An example was the support of Arctic reconnaissance flights from Thule Air Base.

While it was an effective tanker, the KC-97's slow speed and low operational altitude complicated refueling operations with jet aircraft. B-52s typically lowered their flaps and rear landing gear to slow the aircraft enough to refuel from the KC-97. In addition, a typical B-52 refueling engagement profile would involve a descent that allowed the aircraft pair to maintain a higher airspeed (220-240 knots). In the early 1960s, the Tactical Air Command added General Electric J47 jet pods from retired KB-50 tankers to produce the KC-97L. The jet pods increased performance and made the KC-97 more compatible with jet aircraft.

In 1956, SAC began phasing out the KC-97 in favor of the KC-135. KC-97s continued operating with Tactical Air Command, the Air Force Reserve, and the Air National Guard. The KC-97 was finally retired completely in 1978, when the Texas Air National Guard and Utah Air National Guard exchanged their KC-97Ls for C-130s and KC-135s, respectively.

Variants

The KC-97's refueling boom
Source: AIRTime[13]
KC-97A
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.
KC-97E
aerial refueling tankers with rear loading doors permanently closed, 60 built. Some were later converted into transports as the C-97E.
KC-97F
3800hp R-4360-59B engines and minor changes, 159 built. Some were later converted into transport as the C-97F.
KC-97G
Dual-role aerial refueling tankers/cargo transportation aircraft. KC-97G models carried underwing fuel tanks. 592 built.
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.
C-97G
135 KC-97Gs converted to transports.
GKC-97G
Five KC-97Gs were used as ground instruction airframes.
JKC-97G
One aircraft was modified to test the underwing General Electric J47-GE-23 jet engines, and was later designated KC-97L.
HC-97G
KC-97Gs converted for search and rescue operations, 22 converted.
KC-97H
One KC-97F was experimentally converted into a hose-and-drogue refueling aircraft.
YC-97J
two KC-97G conversion with four 4250 kW Pratt & Whitney YT34-P-5 turboprops, dropped in favour of the Boeing KC-135 Stratotanker.
C-97K
27 KC-97Gs converted to troop transports.[14]
KC-97L
81 KC-97Gs modified with two J47 turbojet engines on underwing pylons.

Operators

Spanish Boeing KC-97L Stratofreighter at Albacete (1985)
A KC-97L Stratofreighter (s/n 52-2630 Zeppelinheim) at the National Museum of the United States Air Force
 Spain

 Israel

 United States

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

Active duty

Air National Guard

Accidents and incidents involving the KC-97

Survivors

A number of KC-97s survive, at least two of which are potentially airworthy: 52-2718 / N117GA Angel of Deliverance operated by the Berlin Airlift Historical Foundation.,[32] and N1365N known as Tanker 97 and operated until recently as an aerial firefighting airtanker by Hawkins & Powers.

Static displays include:

In popular culture

The KC-97 Stratofreighter is shown in the 1955 film Strategic Air Command, refueling a B-47 in flight, and in the 1957 film Bombers B-52, refueling B-52s.

Specifications (KC-97L)

Data from USAF Museum[46] and FAS.[47]

General characteristics

Performance

See also

Related development
Aircraft of comparable role, configuration and era
Related lists

References

Citations

  1. Bach, p. 13
  2. Swanborough / Bowers 1989, p. 128.
  3. Bach, p. 31
  4. Bach, p. 14
  5. 1 2 Swanborough / Bowers 1989, p. 127-129.
  6. Boeing History homepage
  7. National Museum of the US Air Force, factsheet Boeing KC-97L Stratofreighter
  8. Bach, p. 12
  9. Bowers 1989, p. 358-359.
  10. Bach, p. 4-7
  11. Bowers 1989, p. 353-358.
  12. Swanborough / Bowers 1989, p. 125-126.
  13. for KC-97: AIRTime Publishing. (2006). International Air Power Review, Vol 20. ISBN 1-880588-91-9
  14. Bowers 1989, p. 364.
  15. Rarenstein, Charles. (1984). Air Force Combat Wings: Lineage and Honors Histories 1947-1977. ISBN 0-912799-12-9
  16. Aviation Safety Network: Accident Description
  17. ASN Aircraft accident Boeing KC-97F-55-BO Stratofreighter 51-0258 Azores Islands
  18. Strategic-air-command.com: Plattsburgh AFB, NY - SAC - 380th Bomb Wing - B-47, B-52, FB111A Retrieved on 2011-12-1.
  19. 1 2 3 4 5 1952 USAF Serial Numbers
  20. JoeBaugher.com: 1952 USAF Serial Numbers, Retrieved on 2011-12-1
  21. Smithsonian Institution, "All That Remains", Air & Space Magazine, Washington, D.C., November 2002. Retrieved on 2011-12-1
  22. AircraftArchaeology.com: KC-97G, #52-2711 crashed 29 Oct 1957, 35 miles north of Flagstaff., Retrieved on 2011-12-1
  23. Associated Press, "Two Chutists Found Safe", Lincoln Evening Journal and Nebraska State Journal, Tuesday 15 December 1959, page 3.
  24. Aviation-Safety.net Accident: 14 Dec 1959 KC-97G Stratofreighter, Retrieved on 2011-12-1
  25. wreck found
  26. http://www.lincolnkings.com/lafb/crashdigest.htm
  27. Member Photos2
  28. MeWreckchasers.com: REMEMBERING THE CREW OF KC-97G 52-2728, by Peter Noddin, Dirago Flyer, October 2001
  29. Langeveld, M.Dirk, Staff Writer, "The ultimate sacrifice; wreck sites a reminder of military plane disasters", Sun Journal, Lewiston, Maine, 12 September 2010. Retrieved on 2011-12-1
  30. SunJournal.com: Oxford Hills The ultimate sacrifice; wreck sites a reminder of military plane disasters, Retrieved on 2011-12-1
  31. ASN Aircraft accident Boeing KC-97G Stratofreighter 4X-FPR/033 Suez Canal
  32. Berlin Airlift Historical Foundation
  33. "Boeing KC-97L Stratofreighter." National Museum of the US Air Force. Retrieved: 22 August 2015
  34. KC-97L STRATOFREIGHTER | Grissom Air Museum
  35. Strategic Air Command & Aerospace Museum
  36. BOEING C-97G STRATOFREIGHTER | Exhibits | Minnesota Air National Guard Museum
  37. KC-97L Stratotanker - Air Mobility Command Museum
  38. 1 2 3 4 5 6 1953 USAF Serial Numbers
  39. Museum Home
  40. .
  41. "Boeing KC-97L". USAF Museum. Retrieved 2011-12-02.
  42. "KC-97 Stratotanker". Federation of American Scientists WMD Resources. Retrieved 2011-12-02.

Bibliography

  • Bach, Martin: Boeing 367 Stratofreighter, Boeing 377 Stratocruiser, Aero Spacelines Guppies. NARA Verlag, Allershausen 1996, ISBN 3-925671-18-8.
  • Bowers, Peter M.: Boeing Aircraft since 1916. Putnam Aeronautical Books, London 1989, ISBN 0-85177-804-6.
  • Swanborough, Gordon and Bowers, Peter M.: United States Military Aircraft since 1909. Putnam Aeronautical Books, London 1989, ISBN 0-85177-816-X.

External links

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