Boeing KC-97 Stratofreighter

The Boeing KC-97 Stratofreighter was 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.''

Operational history


The USAF began operating the KC-97 in 1950. It purchased a total of 811 KC-97s from Boeing, as opposed to only 74 of the C-97 cargo version. The KC-97 used piston engines, fueled by aviation gasoline, but it carried jet fuel for its refueling mission. It therefore used independent (transfer valves) systems for both types of fuel, and was able to transfer its aviation gas 145 to off-load to the receiver in an emergency (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 and Utah Air National Guards exchanged their KC-97Ls for C-130s and KC-135s, respectively.

Variants

 * Source: AIRTime


 * 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.
 * KC-97L
 * 81 KC-97Gs modified with two J47 turbojet engines on underwing pylons.

Operators

 * Spanish Air Force
 * Spanish Air Force

Israel
 * Israel Defense Forces


 * United States Air Force
 * United States Air Force

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

Active duty

 * 2d Bombardment Wing (Medium) - Hunter AFB, Georgia (1953–1963)
 * 2d Air Refueling Squadron
 * 9th Bombardment Wing (Medium) - Mountain Home AFB, Idaho (1954–1965)
 * 9th Air Refueling Squadron
 * 11th Air Refueling Wing - Altus AFB, Oklahoma (1957–1958)
 * 96th Air Refueling Squadron
 * 19th Bombardment Wing (Medium) - Homestead AFB, Florida (1955–1961)
 * 19th Air Refueling Squadron
 * 100th Air Refueling Squadron
 * 303d Air Refueling Squadron
 * 22d Bombardment Wing (Medium) - March AFB, California (1952–1962)
 * 22d Air Refueling Squadron
 * 22d Air Refueling Squadron - (relocated as a GSU to McChord AFB, Washington
 * 320th Air Refueling Squadron
 * 26th Strategic Reconnaissance Wing (Medium) - Lockborne AFB, Ohio (1953–1955; 1956–1958)
 * 26th Air Refueling Squadron
 * 321st Air Refueling Squadron
 * 28th Bombardment Wing (Heavy) - Ellsworth AFB, South Dakota (1962–1964)
 * 97th Air Refueling Squadron - GSU Malmstrom AFB, Montana
 * 40th Bombardment Wing (Medium) Schilling AFB, Kansas(1953–1960)
 * 40th Air Refueling Squadron
 * 42d Bombardment Wing (Heavy) - Limestone AFB, Maine (1955–1957)
 * 42d Air Refueling Squadron
 * 43d Bombardment Wing (Medium) - Davis-Monthan AFB, Arizona (1953–1960)
 * 9th Air Refueling Squadron
 * 43d Air Refueling Squadron
 * 44th Bombardment Wing (Medium) - Lake Charles AFB, Louisiana (1953–1960)
 * 44th Air Refueling Squadron
 * 68th Bombardment Wing (Medium) - Lake Charles AFB, Louisiana (1953–1957)
 * 68th Air Refueling Squadron
 * 70th Strategic Reconnaissance Wing (Medium) - Little Rock AFB, Arkansas (1955–1961)
 * 70th Air Refueling Squadron
 * 90th Bombardment Wing (Medium) - Fairchild AFB, Washington (1955–1960)
 * 90th Air Refueling Squadron
 * 91st Bombardment Wing (Medium) - Glasgow AFB, Montana (1952–1957)
 * 26th Air Refueling Squadron
 * 68th Air Refueling Squadron
 * 91st Air Refueling Squadron
 * 100th Air Refueling Squadron
 * 93d Bombardment Wing (Medium) - Castle AFB, California (1953–1957)
 * 90th Air Refueling Squadron
 * 93d Air Refueling Squadron
 * 96th Bombardment Wing (Medium) - Altus AFB, Oklahoma (1954–1958)
 * 11th Air Refueling Squadron
 * 96th Air Refueling Squadron
 * 321st Air Refueling Squadron
 * 380th Air Refueling Squadron
 * 97th Bombardment Wing (Medium) - Biggs AFB, Texas (1954–1957)
 * 97th Air Refueling Squadron
 * 98th Bombardment Wing (Medium) - Lincoln AFB, Nebraska (1954–1963)
 * 98th Air Refueling Squadron
 * 307th Air Refueling Squadron
 * 100th Bombardment Wing (Medium) - Portsmouth AFB/Pease AFB, New Hampshire (1956–1966)
 * 100th Air Refueling Squadron
 * 509th Air Refueling Squadron
 * 301st Bombardment Wing (Medium) - Barksdale AFB, Louisiana/Lockborne AFB, Ohio (1953–1963)
 * 301st Air Refueling Squadron
 * 303rd Bombardment Wing (Medium) - Davis-Monthan AFB, Arizona (1953–1956; 1960)
 * 9th Air Refueling Squadron
 * 43d Air Refueling Squadron
 * 96th Air Refueling Squadron
 * 303d Air Refueling Squadron
 * 305th Bombardment Wing (Medium) - MacDill AFB, Florida (1951–1959)
 * 305th Air Refueling Squadron
 * 306th Bombardment Wing (Medium) - MacDill AFB, Florida (1951–1962)
 * 306th Air Refueling Squadron
 * 307th Bombardment Wing (Medium) - Lincoln AFB, Nebraska (1955–1960)
 * 307th Air Refueling Squadron
 * 308th Bombardment Wing (Medium) - Hunter AFB, Georgia (1953–1959)
 * 303d Air Refueling Squadron
 * 308th Air Refueling Squadron
 * 310th Bombardment Wing (Medium) - Smoky Hill AFB/Schilling AFB, Kansas (1952–1963)
 * 40th Air Refueling Squadron
 * 310th Air Refueling Squadron
 * 320th Bombardment Wing (Medium) - March AFB, California (1952–1960)
 * 320th Air Refueling Squadron
 * 321st Bombardment Wing (Medium) - Pinecastle AFB, Florida (1954–1956)
 * 307th Air Refueling Squadron
 * 321st Air Refueling Squadron
 * 340th Bombardment Wing (Medium) - Whiteman AFB, Missouri (1954–1962)
 * 34th Air Refueling Squadron
 * 340th Air Refueling Squadron
 * 341st Bombardment Wing (Medium) - Dyess AFB, Texas (1956–1960)
 * 11th Air Refueling Squadron
 * 376th Bombardment Wing (Medium) - Barksdale AFB, Louisiana/Lockborne AFB, Ohio (1953–1963)
 * 91st Air Refueling Squadron
 * 376th Air Refueling Squadron
 * 379th Bombardment Wing - Homestead AFB, Florida (1956)
 * 19th Air Refueling Squadron
 * 384th Air Refueling Wing (Heavy) - Little Rock AFB, Arkansas (1961–1963)
 * 70th Air Refueling Squadron
 * 397th Bombardment Wing (Heavy) - Dow AFB, Maine (1963–1964)
 * 71st Air Refueling Squadron
 * 341st Air Refueling Squadron
 * 407th Strategic Fighter Wing - Great Falls AFB, Montana (1957)
 * 407th Air Refueling Squadron
 * 497th Air Refueling Wing - Plattsburgh AFB, New York (1962–1964)
 * 26th Air Refueling Squadron
 * 380th Air Refueling Squadron
 * 499th Air Refueling Wing - Westover AFB, Massachusetts (1963–1965)
 * 11th Air Refueling Squadron - GSU Dover AFB, Delaware
 * 19th Air Refueling Squadron - GSU Otis AFB, Massachusetts
 * 99th Air Refueling Squadron (Operated KC135 & EC-135 aircraft Only)
 * 303d Air Refueling Squadron - GSU Kindley AFB, Bermuda
 * 305th Air Refueling Squadron- GSU McGuire AFB, New Jersey
 * 384th Air Refueling Squadron - Westover AFB, Massachusetts (1963–1965)
 * 500th Air Refueling Wing - Selfridge AFB, Michigan (1963–1964)
 * 44th Air Refueling Squadron
 * 307th Air Refueling Squadron
 * 509th Bombardment Wing (Heavy) - Walker AFB, New Mexico/Pease AFB, New Hampshire (1954–1965)
 * 509th Air Refueling Squadron
 * 4397th Air Refueling Training Wing - Randolph AFB, Texas (1958–1963)
 * 4397th Combat Crew Training Squadron
 * 4050th Air Refueling Wing - Westover AFB, Massachusetts (1955–1962)
 * 11th Air Refueling Squadron - GSU Dover AFB, Delaware
 * 19th Air Refueling Squadron - GSU Otis AFB, Massachusetts
 * 26th Air Refueling Squadron - Westover AFB, Massachusetts
 * 303d Air Refueling Squadron - GSU Kindley AFB, Bermuda
 * 305th Air Refueling Squadron- GSU McGuire AFB, New Jersey
 * 384th Air Refueling Squadron - Westover AFB, Massachusetts (1963–1965)
 * 4060th Air Refueling Wing - Dow AFB, Maine/Plattsburgh AFB, New York (1955–1962)
 * 4108th Air Refueling Wing - Plattsburgh AFB, New York (1961–1965
 * 4045th Air Refueling Wing - Selfridge AFB, Michigan
 * 4061st Air Refueling Wing - Malmstrom AFB, Montana
 * 4081st Air Refueling Wing - Ernest Harmon AFB, NFLD (19?? - 1966)
 * 376th Air Refueling Squadron

Air National Guard

 * 106th Air Refueling Group - NAS New York/Floyd Bennett Field, then Suffolk County Airport, New York (1962–1972)
 * 102d Air Refueling Squadron
 * 126th Air Refueling Wing - O'Hare International Airport, Illinois (1953–1976)
 * 108th Air Refueling Squadron
 * 128th Air Refueling Wing - General Mitchell Air National Guard Base, Wisconsin (1962–1977)
 * 126th Air Refueling Squadron
 * 134th Air Refueling Wing - McGhee Tyson Air National Guard Base, Tennessee (1964–1977)
 * 151st Air Refueling Squadron
 * 146th Air Transport Wing- Van Nuys, California (1962–1967)
 * 115th Air Refueling Squadron
 * 136th Air Refueling Wing - NAS Dallas, Texas (1965–1978)
 * 181st Air Refueling Squadron
 * 139th Air Refueling Group - Rosecrans Air National Guard Base, Missouri (1969–1976)
 * 180th Air Refueling Squadron
 * 151st Air Refueling Group - Salt Lake City Air National Guard Base, Utah (1972–1978)
 * 191st Air Refueling Squadron
 * 160th Air Refueling Group - Lockborne AFB, Ohio (1965–1975)
 * 145th Air Refueling Squadron
 * 161st Air Refueling Group - Sky Harbor Air National Guard Base, Arizona (1972–1977)
 * 197th Air Refueling Squadron
 * 171st Air Refueling Wing - Pittsburgh IAP Air Reserve Station, Pennsylvania (1972–1977)
 * 147th Air Refueling Squadron

Accidents and incidents involving the KC-97

 * 9 May 1957 – KC-97F 51-0258 en route from Sidi Slimane Air Base, Morocco, to Lajes AB, Azores, ditches in the Atlantic 550 km (343.8 mls) SE of the Azores Islands following a double engine failure, no fatalities amongst the seven crew. The airplane floated for ten days and was sunk by USS Wisconsin.
 * 18 July 1957 – The 380th Bomb Wing suffers its first peacetime major accident when KC-97G 52-2737 from the 380th Air Refueling Squadron with a crew of eight explodes and crashes into Lake Champlain at 2128 hrs. when two of the four engines fail three minutes after take-off from Plattsburgh AFB, New York. Three survivors.
 * 29 October 1957 – KC-97G 52-2711 of the 509th Bomb Wing, out of Walker AFB, New Mexico, crashes 35 miles north of Flagstaff, Arizona, while on nine-hour low-level survey flight to determine minimum altitude restrictions for B-47 training routes. Aircraft was seen over Gray Mountain, Arizona, at altitude of 60 feet shortly after 0830 hrs., and then heard striking a cloud-shrouded cliff face, killing 16 crew and strewing wreckage for 200 yards along mountainside.
 * 14 December 1959 – KC-97G 53-0231 of the 384th Air Refueling Squadron, out of Westover AFB, Massachusetts, collides with a B-52 during a refueling mission at an altitude of ~15,000 feet. The aircraft loses the whole left horizontal stabilizer and elevator, the rudder, and the upper quarter of the vertical stabilizer. Crew makes a no-flap, electrical power off landing at night at Dow AFB, Maine, seven crew okay. "Spokesmen at Dow Air Force, Bangor, said the B52 [sic] apparently 'crowded too close' and rammed a fuel boom into the tail of a four-engined KC95 [sic] tanker plane."  Aircraft stricken as beyond economical repair. Two crew on the B-52 eject, parachute safely, and are recovered by helicopters in a snow-covered wilderness area. The bomber and remaining eight crew members continue to Westover AFB, where a safe landing is made.
 * 15 April 1960 – Twenty-four airmen escape with their lives when KC-97G 52-0919 of the 307th Air Refueling Squadron, 307th Bomb Wing, crashes and burns on take-off from Lincoln AFB, Nebraska, when the undercarriage collapses. The only casualties are two airmen who suffer leg fractures and five others who suffer minor cuts and burns.
 * 27 June 1960 – A KC-97G 52-2728 of the 380th Air Refueling Squadron, Plattsburgh AFB, New York, suffers failure of lubrication on an engine impeller shaft, during an evening four-hour training mission to refuel a Boeing B-47 Stratojet. During rendezvous at 15,500 feet, bomber crew sees the tanker's number one (port outer) powerplant burst into flames. A burning fuel leak threatens the wing integrity. As the bomber moves away from the burning tanker, the crew tries unsuccessfully to put out the blaze. The plane goes into a spin as the wing fails outboard of the engine and crashes on Jonathan Smith Mountain, a hill east of Puzzle Mountain in Newry, Maine. The flash of the fire is seen from as far away as Lewiston and Bridgton, and several people witness the crash, including hundreds of moviegoers at the Rumford Point Drive-In. All five crew are killed – two are found wearing unused parachutes. Wreckage covers five acres and was still there in 2010.
 * 17 September 1971 – KC-97G 4X-FPR/033 of the Israeli Air Force, is shot down by Egyptian missiles over Suez, Egypt, seven of eight-man crew on board killed.

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., and N1365N known as Tanker 97 and operated until recently as an aerial firefighting airtanker by Hawkins & Powers.

Static displays include:
 * 52-0895–Rogue Valley International-Medford Airport in Central Point, Oregon, registered as N1365D.
 * 52-0905– Wisconsin National Guard Museum at Volk Field Air National Guard Base in Camp Douglas, Wisconsin.
 * 52-2624– At the now-closed Florence Air & Missile Museum, Florence, South Carolina.
 * 52-2630– National Museum of the United States Air Force at Wright-Patterson Air Force Base near Dayton, Ohio.
 * 52-2694– Located at Grant County International Airport, Moses Lake, Washington. Seen wearing civil registration N31338.
 * 52-2697– Grissom Air Museum at Grissom Air Reserve Base (former Grissom AFB) in Peru, Indiana.
 * 52-2961– Located in Greybull, Wyoming, registered as N29862.
 * 53-0151– Pima Air and Space Museum adjacent to Davis-Monthan Air Force Base in Tucson, Arizona.
 * 53-0198– Strategic Air and Space Museum adjacent to Offutt Air Force Base in Ashland, Nebraska.
 * 53-0218– Minnesota Air National Guard Museum, St. Paul, Minnesota. Displayed in C-97G configuration.
 * 53-0230– Air Mobility Command Museum at Dover Air Force Base, Delaware.
 * 53-0240– Eighth Air Force Museum at Barksdale Air Force Base, Louisiana.
 * 53-0280– Tail section preserved in Zruč nad Sázavou, Czech Republic, registered as N49548.
 * 53-0282– Dyess Air Force Base in Abilene, TX.
 * 53-0283– Solo's Restaurant adjacent to Peterson Air Force Base and Colorado Springs Municipal Airport in Colorado Springs, Colorado.
 * 53-0298– Museum of Aviation at Robins Air Force Base in Georgia.
 * 53-0327– Whiteman Air Force Base in Knob Noster, Missouri.
 * 53-0335– Carolinas Aviation Museum at Charlotte-Douglas International Airport in Charlotte, North Carolina.
 * 53-0354– Castle Air Museum at the former Castle Air Force Base in Atwater, California.
 * 53-0363– March Field Air Museum at March Air Reserve Base (former March AFB) in Riverside, California.
 * 53-0360– Malmstrom Museum, Malmstrom Air Force Base, Montana. Displayed as 52-2638.
 * TK1-3– Museo del Aire (Spain) at Cuatro Vientos Airport in Madrid, Spain. Former USAF aircraft, AF Ser. No. 53-0189.

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.