Boeing KC-97 Stratofreighter

The Boeing KC-97 Stratofreighter is a four-engined, piston-powered United States strategic tanker aircraft based on the Boeing C-97 Stratofreighter. It replaced the KB-29 and 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, greatly modified with all the necessary tanks, plumbing, and a flying boom first developed for the KB-29 bomber. The cavernous upper deck was capable of accommodating oversize cargo accessed through a very large right-side door. In addition, transferable jet fuel was contained in tanks on the lower deck. Both decks were heated and pressurized for high altitude operations. The boom operator lay prone, viewing operations through a window at the bottom of the tail, a configuration later used on the KC-135.
''Note: Occasionally the KC-97 has been referred to 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 received a total of 811 KC-97s from Boeing, as opposed to only 74 of the C-97 cargo version, while ordering 819 KC-97s and 74 C-97s. 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 in an emergency, it was able to also offload its aviation gas to a receiver in a procedure universally 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.
During Operation Creek Party, which started in 1967 and lasted for 10 years, Air National Guard and Air Force Reserve tankers supported active duty USAF and NATO units in Europe, including an 160th Air Refueling Group Ohio Air National Guard KC-97L.
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. In the early 1960s, the Tactical Air Command added General Electric J47 two twin- jet pods from retired KB-50 aerial tankers to produce the KC-97L. These jet pods increased the speed of the KC-97 and made it more compatible with jet fighter planes like the F-84, F-100, and F-101.
In 1956, the Strategic Air Command began phasing out its KC-97s in favor of the KC-135 Stratotanker. KC-97s continued flying with Tactical Air Command, the Air Force Reserve, and the Air National Guard. The rest of the KC-97s were retired completely in 1978, when the Texas Air National Guard and the Utah Air National Guard exchanged their KC-97Ls for the C-130 Hercules and the KC-135 Stratotanker, respectively.
One KC-97 airframe was adapted into the Aero Spacelines Super Guppy, a transport plane designed to carry Apollo Program rocket stages from California to Florida. The aircraft carried the Saturn S-IVB stage, which served as the second stage of the Saturn IB, the third stage of the Saturn V, and the fourth stage for the never-built Nova rocket.
This modified KC-97, constructed in 1953, was eventually purchased by NASA in 1997. It is still in service supporting NASA, other Federal agencies, and Federal contractors. It is one of two KC-97s left still in flyable condition, the other being former KC-97G 52-2718, "Angel of Deliverance", currently flown by Berlin Airlift Historical Foundation as YC-97A 45-59595.

Variants

;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: Company designation Model 367-4-29. Aerial refueling tankers with rear loading doors permanently closed, 60 built. Some were later converted into transports as the C-97E.
;KC-97F: Company designation Model 367-76-29. 3800 hp R-4360-59B engines and minor changes, 159 built. Some were later converted into transport as the C-97F.
;KC-97G: Company designation Model 367-76-66. 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 Central Intelligence Agency 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: Company designation Model 367-86-542. 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.
The codenames "Eager Beaver" and "Rivet Box" were used for Big Safari-built photoreconnaissance modifications to the C-97G for the 7405th Support Squadron along the Berlin air corridors.

Operators

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

Active duty

2d Bombardment Wing – Hunter AFB, Georgia
*2d Air Refueling Squadron
9th Bombardment Wing – Mountain Home AFB, Idaho
*9th Air Refueling Squadron
11th Air Refueling Wing – Altus AFB, Oklahoma
*96th Air Refueling Squadron
19th Bombardment Wing – Homestead AFB, Florida
*19th Air Refueling Squadron
*100th Air Refueling Squadron
*303d Air Refueling Squadron
22d Bombardment Wing – March AFB, California
*22d Air Refueling Squadron
*22d Air Refueling Squadron –
*320th Air Refueling Squadron
26th Strategic Reconnaissance Wing – Lockborne AFB, Ohio
*26th Air Refueling Squadron
*321st Air Refueling Squadron
28th Bombardment Wing – Ellsworth AFB, South Dakota
*97th Air Refueling Squadron – GSU Malmstrom AFB, Montana
40th Bombardment Wing Schilling AFB, Kansas
*40th Air Refueling Squadron
42d Bombardment Wing – Limestone AFB, Maine
*42d Air Refueling Squadron
43d Bombardment Wing – Davis-Monthan AFB, Arizona
*9th Air Refueling Squadron
*43d Air Refueling Squadron
44th Bombardment Wing – Lake Charles AFB, Louisiana
*44th Air Refueling Squadron
68th Bombardment Wing – Lake Charles AFB, Louisiana
*68th Air Refueling Squadron
70th Strategic Reconnaissance Wing – Little Rock AFB, Arkansas
*70th Air Refueling Squadron
90th Bombardment Wing – Fairchild AFB, Washington
*90th Air Refueling Squadron
91st Bombardment Wing – Glasgow AFB, Montana
*26th Air Refueling Squadron
*68th Air Refueling Squadron
*91st Air Refueling Squadron
*100th Air Refueling Squadron
93d Bombardment Wing – Castle AFB, California
*90th Air Refueling Squadron
*93d Air Refueling Squadron
96th Bombardment Wing – Altus AFB, Oklahoma
*11th Air Refueling Squadron
*96th Air Refueling Squadron
*321st Air Refueling Squadron
*380th Air Refueling Squadron
97th Bombardment Wing – Biggs AFB, Texas
*97th Air Refueling Squadron
98th Bombardment Wing – Lincoln AFB, Nebraska
*98th Air Refueling Squadron
*307th Air Refueling Squadron
100th Bombardment Wing – Portsmouth AFB/Pease AFB, New Hampshire
*100th Air Refueling Squadron
*509th Air Refueling Squadron
301st Bombardment Wing – Barksdale AFB, Louisiana/Lockborne AFB, Ohio
*301st Air Refueling Squadron
303rd Bombardment Wing – Davis-Monthan AFB, Arizona
*9th Air Refueling Squadron
*43d Air Refueling Squadron
*96th Air Refueling Squadron
*303d Air Refueling Squadron
305th Bombardment Wing – MacDill AFB, Florida
*305th Air Refueling Squadron
306th Bombardment Wing – MacDill AFB, Florida
*306th Air Refueling Squadron
307th Bombardment Wing – Lincoln AFB, Nebraska
*307th Air Refueling Squadron
308th Bombardment Wing – Hunter AFB, Georgia
*303d Air Refueling Squadron
*308th Air Refueling Squadron
310th Bombardment Wing – Smoky Hill AFB/Schilling AFB, Kansas
*40th Air Refueling Squadron
*310th Air Refueling Squadron
320th Bombardment Wing – March AFB, California
*320th Air Refueling Squadron
321st Bombardment Wing – Pinecastle AFB, Florida
*307th Air Refueling Squadron
*321st Air Refueling Squadron
340th Bombardment Wing – Whiteman AFB, Missouri
*34th Air Refueling Squadron
*340th Air Refueling Squadron
341st Bombardment Wing – Dyess AFB, Texas
*11th Air Refueling Squadron
376th Bombardment Wing – Barksdale AFB, Louisiana/Lockborne AFB, Ohio
*91st Air Refueling Squadron
*376th Air Refueling Squadron
379th Bombardment Wing – Homestead AFB, Florida
*19th Air Refueling Squadron
384th Air Refueling Wing – Little Rock AFB, Arkansas
*70th Air Refueling Squadron
397th Bombardment Wing – Dow AFB, Maine
*71st Air Refueling Squadron
*341st Air Refueling Squadron
407th Strategic Fighter Wing – Great Falls AFB, Montana
*407th Air Refueling Squadron
497th Air Refueling Wing – Plattsburgh AFB, New York
*26th Air Refueling Squadron
*380th Air Refueling Squadron
499th Air Refueling Wing – Westover AFB, Massachusetts
*11th Air Refueling Squadron – GSU Dover AFB, Delaware
*19th Air Refueling Squadron – GSU Otis AFB, Massachusetts
*99th Air Refueling Squadron
*303d Air Refueling Squadron – GSU Kindley AFB, Bermuda
*305th Air Refueling Squadron- GSU McGuire AFB, New Jersey
*384th Air Refueling Squadron – Westover AFB, Massachusetts
500th Air Refueling Wing – Selfridge AFB, Michigan
*44th Air Refueling Squadron
*307th Air Refueling Squadron
509th Bombardment Wing – Walker AFB, New Mexico/Pease AFB, New Hampshire
*509th Air Refueling Squadron
4397th Air Refueling Training Wing – Randolph AFB, Texas
* 4397th Combat Crew Training Squadron
4050th Air Refueling Wing – Westover AFB, Massachusetts
*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
4060th Air Refueling Wing – Dow AFB, Maine/Plattsburgh AFB, New York
4108th Air Refueling Wing – Plattsburgh AFB, New York
4045th Air Refueling Wing – Selfridge AFB, Michigan
4061st Air Refueling Wing – Malmstrom AFB, Montana
* 407th Air Refueling Squadron
4081st Strategic Wing – Ernest Harmon AFB, Newfoundland, Canada
*376th Air Refueling Squadron