Boeing C-97 Stratofreighter
|Role||Military transport aircraft|
|First flight||9 November 1944|
|Primary users||United States Air Force
Israeli Air Force
|Number built||60 (total of 888 in all variants)|
|Developed from||Boeing B-29 Superfortress
Boeing B-50 Superfortress
|Variants||Boeing KC-97 Stratotanker
Boeing 377 Stratocruiser
Aero Spacelines Pregnant Guppy
Aero Spacelines Super Guppy
Aero Spacelines Mini Guppy
The Boeing C-97 Stratofreighter was a long-range heavy military cargo aircraft based on the B-29 bomber. Design work began in 1942, with the prototype's first flight being on 9 November 1944, and the first production aircraft entered service in 1947. Between 1947 and 1958, 888 C-97s in several versions were built, 816 being KC-97 tankers. C-97s served in the Berlin Airlift, the Korean War, and the Vietnam War. Some aircraft served as flying command posts for the Strategic Air Command, while others were modified for use in Aerospace Rescue and Recovery Squadrons (ARRS).
Design and development
The C-97 Stratofreighter was developed towards the end of World War II by fitting an enlarged upper fuselage onto a lower fuselage and wings which were essentially the same as those of the B-50 Superfortress with the tail, wing, and engine layout being nearly identical. It was built before the death of Boeing president Philip G. Johnson. It can be easily distinguished from the 377 Stratocruiser by the "beak" radome beneath the nose and by the flying boom and jet engines on later tanker models.
The prototype XC-97 was powered by the 2,200 hp (1,600 kW) Wright R-3350 engine, the same used in the B-29. This aircraft and the other pre-production examples were fitted with a shorter fin and rudder than used subsequently. The C-97 had clamshell doors under its tail, so that a retractable ramp could be used to drive in cargo. However, unlike the later Lockheed C-130 Hercules, it was not designed as a combat transport which could deliver directly to primitive forward bases using relatively short takeoffs and landings. The rear ramp could not be used in flight for air drops.
On 9 January 1945, the first prototype, piloted by Major Curtin L. Reinhardt, flew from Seattle to Washington, DC in 6 hours 4 minutes, an average speed of 383 mph (616 km/h) with 20,000 lb (9,100 kg) of cargo, which was for its time impressive for such a large aircraft. Production models featured the 3,500 hp (2,600 kW) Pratt & Whitney Wasp Major engine, the same engine as for the B-50.
The C-97 had a useful payload of 35,000 lb (16,000 kg) and could carry two normal trucks, towed artillery, or light tracked vehicles such as the M56 Scorpion. The C-97 was also the first mass-produced air transport to feature cabin pressurization, which made long range missions somewhat more comfortable for its crew and passengers.
One YC-97A (45-9595) was used in the Berlin Airlift during April 1949 operating for the 1st Strategic Support Squadron. It suffered a landing gear accident at Rhein Main Air Base and by the time it was repaired, the Soviet Blockade was lifted.
C-97s evacuated casualties during the Korean War. C-97s also participated in the Biafran airlift, delivering relief materials to Uli airstrip in Biafra during the Nigerian Civil War. Flying under the cover of darkness and at treetop level to evade radar, at least two C-97s were lost.
The USAF Strategic Air Command operated C-97 Stratofreighters from 1949-1978. Early in its service life, it served as an airborne alternative SAC command post. While only 60 C-97 transports were built, 816 were built as KC-97 Stratotankers for inflight refueling. Many KC-97s were later refitted as C-97G transports and equipped several squadrons of the US Air National Guard.
The civilian derivative of the C-97 was the Boeing 377 Stratocruiser, a very luxurious transoceanic airliner which featured a lower deck lounge and could be fitted with sleeper cabins.
Two C-97s are still airworthy at the present day, one (s/n 52-2718, named "Angel of Deliverance") operated as a privately owned warbird, the other operated as a fire bomber in the United States.
The Israelis turned to Stratocruisers and KC-97s when they could not buy the highly regarded C-130. The Israelis adapted Boeing 377 Stratocruiser airliners into transports, including many using C-97 tail sections including the loading ramp. Others were adapted with swiveling tails and refueling pods. One Israeli C-97 was downed by an Egyptian SA-2 Guideline missile on 17 September 1971, while flying as an electronic counter-measures platform some 12 miles from the Suez Canal.
- military designation of the prototype Boeing 367, three built.
- cargo transport, six built.
- troop carrier, three built.
- fitted with 80 airliner-style seats, one in 1954 redesignated VC-97D, retired to MASDC 15 December 1969.
- transport, 50 built.
- 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.
- medical evacuation transports, 14 C-97As converted during the Korean War (also designated MC-97).
- staff transport conversions, one YC-97A, two C-97As converted, plus the YC-97B. Later designated C-97D.
- KC-97Es converted to transports.
- aerial refueling tankers with rear loading doors permanently closed; 60 built.
- KC-97Fs converted to transports.
- 3800hp R-4360-59B engines and minor changes; 159 built.
- 135 KC-97Gs converted to transports.
- ELINT conversion of three KC-97Gs. 53-106 was operated by the CIA for covert ELINT operations in the West Berlin Air Corridor.
- dual-role aerial refueling tankers/cargo transportation aircraft. KC-97G models carried underwing fuel tanks; 592 built.
- Five KC-97Gs were used as ground instruction airframes.
- One aircraft was modified to test the underwing General Electric J47-GE-23 jet engines, and was later designated KC-97L.
- KC-97Gs converted for search and rescue operations; 22 converted.
- One KC-97F was experimentally converted into a probe-and-drogue refueling aircraft.
- KC-97G conversion with four 5,700 hp (4,250 kW) Pratt & Whitney YT34-P-5 turboprops; dropped in favour of the KC-135 Stratotanker; two converted
- KC-97Gs converted to troop transports.
- 81 KC-97Gs modified with two J47 turbojet engines on underwing pylons.
U.S. Air Force Units
The following Air Force wing organizations flew the various C-97 models at some time during their existence:
Air National Guard
- 105th Aeromedical Transport Group - Westchester County Airport, New York (1962–1969)
- 137th Air Transport Squadron
- 106th Air Transport Group - Suffolk County Airport, New York
- 102d Air Transport Squadron
- 109th Air Transport Group - Schenectady Airport, New York
- 139th Air Transport Squadron
- 111th Air Transport Group - NAS Willow Grove, Pennsylvania
- 103d Air Transport Squadron
- 116th Air Transport Group - Dobbins ARB, Georgia
- 128th Air Transport Squadron (Heavy)
- 118th Air Transport Group - Nashville International Airport, Tennessee
- 105th Air Transport Squadron
- 126th Air Refueling Wing - O'Hare Airport, Illinois
- 133d Air Transport Wing - Minneapolis-St Paul International Airport, Minnesota
- 109th Air Transport Squadron (Heavy)
- 137th Air Transport Group - Will Rogers World Airport, Oklahoma
- 185th Air Transport Squadron
- 138th Air Transport Group - Tulsa International Airport, Oklahoma
- 125th Air Transport Squadron
- 139th Air Transport Group - Rosecrans Air National Guard Base, Missouri
- 146th Air Transport Wing - NAS Point Mugu, California
- 115th Air Transport Squadron (Heavy)
- 195th Air Transport Squadron (Heavy)
- 151st Air Transport Wing - Salt Lake City International Airport, Utah
- 191st Air Transport Squadron (Heavy)
- 157th Air Transport Group - Grenier Field, New Hampshire
- 133d Air Transport Squadron
- 161st Air Transport Group - Sky Harbor International Airport, Arizona (1966–1972)
- 197th Air Transport Squadron
- 162d Air Transport Wing -, Arizona
- 164th Air Transport Group - Memphis International Airport, Tennessee
- 155th Air Transport Squadron (Heavy)
- 165th Air Transport Group - Savannah International Airport, Georgia
- 158th Air Transport Squadron (Heavy)
- 166th Air Transport Group - Greater Wilmington Airport, Delaware
- 142d Air Transport Squadron
- Berlin Airlift Historical Foundation
- Foundation for Airborne Relief (USA)
- Hawkins & Powers Aviation
- Zantop Air Transport
Accidents and incidents
- 22 May 1947 - A USAF XC-97, 43-27472, crashed in a wheat field near Wright-Patterson Air Force Base and caught fire, killing five of seven crew on board.
- 6 June 1951 - A USAF C-97A, 48-0398, crashed near Kelly Air Force Base due to a possible asymmetric flap extension on takeoff, killing all nine crew on board.
- 15 October 1951 - After taking off from Lajes Field, Azores, a Boeing C-97A of the Military Air Transport Service went missing on a flight back to Westover Air Force Base, Massachusetts. The aircraft was piloted by Captain John Francis Dailey, Jr. and had a crew of 11. A total of 50 aircraft and ships searched the intended route but no trace of the aircraft or crew was ever found.
- 22 October 1951 - A USAF C-97A, 48-0413, crashed next to a runway at Kelly AFB, killing four of six on board.
- 22 March 1957 - A USAF C-97C, 50-0702, en route to Tokyo went missing over the Pacific Ocean, with 10 crew and 57 passengers on board. It is the deadliest incident ever involving the C-97.
- 19 January 1958 - A USAF C-97A, 49-2597, en route to Wake Island from Honolulu went missing over the Pacific Ocean with seven crew on board.
- 26 September 1969 - A Nordchurchaid C-97G, registration N52676, struck trees and crashed while on final approach to Uli Airstrip, killing all five on board.
- 30 July 1987 - After taking off, a C-97 operated by Belize Air International (a cargo airline) crashed onto the Mexico City-Toluca highway, killing 5 of the 12 people on board and 44 people on the ground.
- C-97G 52-898 is on display at the Chanute Aerospace Museum (former Chanute AFB) in Rantoul, Illinois.
- C-97G 52-2626 is on display at the Pima Air & Space Museum, adjacent to Davis-Monthan AFB in Tucson, Arizona.
- C-97G 52-2718 "Angel of Deliverance" is under restoration to flight status by Berlin Airlift Historical Foundation at Hangar B of Floyd Bennett Field.
- C-97G N227AR (the former USAF serial number 52-2764) is on display at the Don Q Inn, next to the (now closed) Dodgeville Municipal Airport outside Dodgeville, Wisconsin. It was used for filming commercials and has a fuselage signed by Farrah Fawcett 
- C-97G 53-0272 is on display at the Milestones of Flight Museum, Fox Field, Lancaster, California.
- KC-97G ex USAF 52-2799, c/n 035/4X-FPO is on display at the Israeli Air Force Museum, Hatzerim Airbase, Beersheba, Israel.
- C-97G (ex KC-97L) USAF 53-0218 is on display at the Minnesota Air National Guard Museum at the Minneapolis-St. Paul Airport.
- C-97 USAF tail number 20895 at 2070 Milligan Way Medford, OR 97504; 42.375306, -122.881770 on edge of Rogue Valley International-Medford Airport
- Crew: 4 (Pilot, Copilot, Navigator, Flight engineer)
- 96 troops or
- 69 stretchers or
- tanker equipment
- Length: 110 ft 4 in (33.7 m)
- Wingspan: 141 ft 3 in (43.1 m)
- Height: 38 ft 3 in (11.7 m)
- Wing area: 1,734 ft² (161.1 m²)
- Empty weight: 82,500 lb (37,410 kg)
- Loaded weight: 120,000 lb (54,420 kg)
- Useful load: 37,500 lb (17,010 kg)
- Max. takeoff weight: 175,000 lb (79,370 kg)
- Powerplant: 4 × Pratt & Whitney R-4360B Wasp Major radial engines, 3,500 hp (2,610 kW) 28-cylinders each
- Maximum speed: 375 mph (603 km/h)
- Cruise speed: 260 knots (300 mph, 482 km/h)
- Range: 4,949 nm (4,300 mi, 6,920 km)
- Ferry range: 5,000 nm (5,760 mi, 9,270 km)
- Service ceiling: 35,000 ft (10,670 m)
- Wing loading: 69.2 lb/ft² (337.8 kg/m²)
- Power/mass: 0.117 hp/lb (192 W/kg)
- Related development
- Aero Spacelines Mini Guppy
- Aero Spacelines Pregnant Guppy
- Aero Spacelines Super Guppy
- Boeing B-50 Superfortress
- Boeing 377 Stratocruiser
- Boeing KC-97 Stratotanker
- Aircraft of comparable role, configuration and era
- Douglas C-54 Skymaster
- Lockheed C-69 Constellation
- Convair XC-99
- Douglas C-118 Liftmaster
- Lockheed C-121 Constellation
- Douglas C-124 Globemaster II
- Lockheed C-130 Hercules
- Lockheed R7V-2/YC-121F Constellation
- Related lists
- "ASN Aviation Safety Database." Aviation Safety Network, Flight Safety Foundation. Retrieved: 27 April 2009.
- Rubinstein and Goldman 1979, p. 89.
- "East of the Suez". Israeli Air Force official website. Retrieved 19 February 2013.
- Ravenstein, Charles A., ed. Air Force Combat Wings: Lineage and Honors Histories, 1947–1977. Washington, D.C.: United States Air Force Historical Research Center, Office of Air Force History, 1984. ISBN 0-912799-12-9.
- "A Mission of History, Education and Remembrance." Spirit of Freedom, 2011. Retrieved: 21 October 2011.
- Accident description for 43-27472 at the Aviation Safety Network. Retrieved on 26 January 2013.
- Accident description for 48-0398 at the Aviation Safety Network. Retrieved on 26 January 2013.
- Union News, Springfield, Massachusetts, 16 October 1951.
- Accident description for 48-0413 at the Aviation Safety Network. Retrieved on 26 January 2013.
- Accident description for 50-0702 at the Aviation Safety Network. Retrieved on 26 January 2013.
- Accident description for 49-2597 at the Aviation Safety Network. Retrieved on 26 January 2013.
- Accident description for N52676 at the Aviation Safety Network. Retrieved on 26 January 2013.
- "Accident Report: Boeing C-97 Stratofreighter G, 30 July 1987." Aviation Safety Network. Retrieved: 21 October 2011.
- "C-97G AF Serial No. 52-898." aeromuseum.org. Retrieved: 13 November 2010.
- "C-97G AF Serial No. 52-2626." pimaair.org. Retrieved: 13 November 2010.
- "C-97G AF Serial No. 52-2718 'Angel of Deliverance'." spiritoffreedom.org. Retrieved: 13 November 2010.
- Leuw, Rudi. "C-97G AF Serial No. 52-2764 showing civil registry N227AR." ruudleeuw.com. Retrieved: 13 November 2010.
- "C-97G AF Serial No. 53-0272." pimaair.org. Retrieved: 13 November 2010.
- "Israeli Air Force Museum Unofficial Museum Guide." aeroflight.co.uk. Retrieved: 8 November 2011.
- "Boeing C-97G Stratofreighter USAF Serial Number 53-0218" Retrieved: 23 December 2012
- "Boeing - History - C-97 Stratofreighter." Boeing. Retrieved: 27 April 2009.
- Hansen, Dave. "Boeing C-97 Stratofreighter." Warbird Alley, 27 April 2009.
- "C-97 Stratofreighter Specifications." GlobalSecurity.org, 27 April 2009.
- Rubinstein, Murray and Richard Goldman. The Israeli Air Force Story London: Arms & Armour Press, 1979. ISBN 0-85368-462-6.
|Wikimedia Commons has media related to C-97 Stratofreighter.|
- How to Fly the C97
- Airliners.net - The Boeing C-97 Stratofreighter
- Angel of deliverance: Boeing C-97G sn 52-2718
- Goleta Air & Space Museum - Boeing C-97 Stratofreighter/Stratotanker
- PhotoValet - Air Force Military Aircraft: Boeing C-97 and KC-97 Stratotanker/Stratofreighter images
- Newsreel introducing the C97 showing rear ramp