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 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 (G-L models). 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
A Boeing KC-97 Stratofreighter's refueling boom operator's station from the National Museum of the US Air Force
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.[6][7]
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 in an emergency, it was able to also offload its aviation gas to a receiver in a procedure universally known as a "save".[13]
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 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 (for short periods of time) and made it more compatible with jet fighter planes like the F-84, F-100, and F-101.
One KC-97 airframe (AF Ser. No. 52-0828)[14] 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.
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
3800 hp R-4360-59B engines and minor changes, 159 built. Some were later converted into transport as the C-97F.
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.[19]
6 July 1956
USAF KC-97E 51-0220 crashed in a wooded area 45 mile northeast of Goose Bay, Canada after reporting an engine fire, killing all six on board.[20]
KC-97F AF Ser. No. 51-0258 en route from Sidi Slimane Air Base, Morocco, to Lajes AB, Azores, ditched in the Atlantic 550 km (343.8 mls) SE of the Azores Islands following a double engine failure. All seven crew survived. The airplane floated for ten days before being sunk by the battleship USS Wisconsin.[23]
18 July 1957
KC-97G AF Ser. No. 52-2737 from the 380th Air Refueling Squadron with a crew of eight, exploded and crashed into Lake Champlain at 2128 hrs., when two of the four engines failed three minutes after take-off from Plattsburgh AFB, New York.[24] There were three survivors.[25]
29 October 1957
KC-97G AF Ser. No. 52-2711 of the 509th Bomb Wing,[26] out of Walker AFB, New Mexico, crashed 35 miles north of Flagstaff, Arizona, while on a nine-hour low-level survey flight to determine minimum altitude restrictions for B-47 training routes. The 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.[27][28]
KC-97G AF Ser. No. 53-0231 of the 384th Air Refueling Squadron, out of Westover AFB, Massachusetts, collided with a B-52 during a refueling mission at an altitude of ~15,000 feet. The aircraft lost the whole left horizontal stabilizer and elevator, the rudder, and the upper quarter of the vertical stabilizer. The crew made 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."[32] Aircraft stricken as beyond economical repair. Two crew on the B-52 ejected, parachuted safely, and were recovered by helicopters in a snow-covered wilderness area. The bomber and remaining eight crew safely landed at Westover AFB.[33]
30 March 1960
KC-97 AF Ser. No. 51-0363 (Manufacturer's Serial Number 16430) ditched and sank off Cape Canaveral. This particular aircraft was lost due to engine damage caused by hail. The crash resulted in 3 fatalities of the 14 crew. The wreck of the aircraft was discovered June 6, 2015, in 365 feet of water by divers.[34]
KC-97G AF Ser. No. 52-2728 of the 380th Air Refueling Squadron, Plattsburgh AFB, New York, suffered 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, the tanker's number one (port outer) powerplant caught fire. As the bomber moved away from the burning tanker, the crew tried unsuccessfully to put out the blaze. The plane went into a spin as the wing failed outboard of the engine; the aircraft crashed on Jonathan Smith Mountain, a hill east of Puzzle Mountain in Newry, Maine. The flash of the fire was seen from as far away as Lewiston and Bridgton. All five crew were killed. Wreckage covering five acres was still there as of 2010.[37][38][39]
28 February 1961
KC-97 AF Ser. No. UNKNOWN of Selfridge Air Force Base, MI. Aircraft crashed shortly after take-off due to engine failure. All five crew members were killed. The aircraft struck houses and an ornamental windmill that was a landmark along Gratiot Rd. (M-25), just north of the base. The attached article incorrectly identifies Selfridge AFB as Selfridge ANGB. Selfridge was not transferred to the Air National Guard until 1 July, 1971. https://www.baaa-acro.com/crash/crash-boeing-kc-97-stratotanker-selfridge-afb-5-killed
5 November 1964
KC-97 AF Ser. No. unknown of Pease Air Force Base crashed on takeoff; all five crewmen were killed.[40][41][42]
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.[43]
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.[44]
17 September 1971
KC-97G IAF Serial 4X-FPR/033 of the Israeli Air Force, was shot down by Egyptian missiles over Suez, Egypt; seven of eight-man crew were killed.[45]
The KC-97 Stratofreighter is shown in both its cargo and tanker tasks 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)
3-view line drawing of the Boeing KC-97G Stratofreighter
Data from USAF Museum,[75] FAS: KC-97 Stratotanker[76]
^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
.jpg)
