Boeing C-97 Stratofreighter Transport Aircraft
The C-97 Stratofreighter was a critical product for both Boeing and the US military throughout the 1950s and 1960s.
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A post-World War 2 design, the C-97 was developed by The Boeing Company from its Model 367 product - a military-minded transport airframe originating from the successful Boeing B-29/B-50 Superfortress heavy bomber design. As such, many of the design elements found on the B-29/B-50 are apparent in the C-97 including the wings and tail sections. The C-97 saw service during the Berlin Airlift (1949) and in the Korea War (1950-1953), for the latter primarily utilized to shuttle casualties, sometimes at tree-top altitudes to avoid enemy eyes. Others were eventually stationed as air command posts and in-flight refueling tankers for Strategic Air Command (SAC). 60 x C-97's were built over the span of a decade. First flight was on November 9th , 1944 as one of three XC-97 prototypes while the final C-97 was retired from service in 1978. The C-97 gave good service during its time aloft, totaling 888 examples when including all of its available variants beyond the standard C-97. The 377 Stratocruiser was the civilian passenger transport of the C-97. 56 of these aircraft were completed and operated by Pan Am, BOAC and Northwest. The Aero Spacelines "Pregnant Guppy", "Super Guppy" and "Mini Guppy" are all based on the Model 367/C-97.
Externally, the C-97 was designed as a mammoth aircraft with a lengthy wingspan mounting four engines, a deep-volume ("double-lobed") fuselage and a traditional empennage. The flight deck was situated in an elevated position at the extreme front of the aircraft. The deep fuselage allowed for various internal arrangements to be had. Each wing managed two engine nacelles along their leading edge. Power was served through 4 x Pratt & Whitney R-4360B Wasp Major radial piston engines delivering 3,500 horsepower each while powering four-bladed propellers. The aircraft could reach a top speed of 375 miles per hour and cruise at 300 miles per hour up to a ceiling of 35,000 feet and range out to 4,300 miles. Internally, the pressurized cargo hold could house 96 infantry or 69 medical patients with staff. In the air tanker role, the C-97 was instead outfitted with large fuel stores which fed awaiting aircraft via a single directional boom at the base of the tail. The cargo hold was accessed through clamshell doors along the belly of the fuselage. The undercarriage was fully retractable and consisted of a double-wheeled nose leg and twin-wheeled main legs. A radar was housed in a chin radome which immediately differentiated the design from the similar 377 Stratocruiser series. The standard operating crew (in basic C-97 transport configuration) was two pilots, a navigator and a flight engineer.
The C-97 was undoubtedly a large aircraft. Its wingspan measured over 141 feet and the fuselage was over 110 feet long. Height was listed at over 38 feet. When empty, the C-97 displaced at 82,500lbs and this ballooned to 175,000lbs when under full load.
Cargo evaluation versions existed under the YC-97 designation and six were produced. The YV-97A was an evaluation troop transport of which three were manufactured and the YV-97B was an evaluation type featuring passenger seating for 80 though only one example was converted as such. The initial production model was the C-97A of which 50 were delivered. Three were converted to the air tanker role as the KC-97A and then returned to C-97A standard after testing. The C-97C was a MEDEVAC variant built from 14 C-97A models during the Korean War. The C-97E was a transport as was the C-97F. Both of these were born from the KC-97E and KC-97F air tankers (60 and 159 built respectively). The KC-97G was another air tanker in 592 examples then converted into 135 KC-97G transport. 81 KC-97Gs were converted as troop transports under the C-97K designation. The C-97 existed in many other specialized forms including training, search and rescue (SAR), turbojet testbed and ELINT.
Operators of the C-97 (beyond the United States) went on to include Israel and Spain. Ex-USAF airframes found their way to the Air National Guard as transports while others found their way into private hands. Some has survived as restored/protected museum pieces.