Boeing KC-97L Stratocruiser
The range of the B-29 Superfortress immediately interested Boeing in developing a passenger version for postwar use; this would make transatlantic and Hawaii flying routes economical for the first time. Since the standard B-29 fuselage would be inadequate for passengers, Boeing designers added a larger-diameter fuselage atop the old B-29 fuselage, resulting in a “double-bubble” appearance. The tail and engines of the B-50 advanced version of the Superfortress were adapted to what would become the Model 377 Stratocruiser. While only 55 Model 377s entered airline service, quickly eclipsed by the jet age, they were considered luxurious for their time, with the lower deck being used for airborne lounges or sleeping compartments, all in pressurized comfort—a first for the airline industry.
The USAF developed the C-97 Stratofrieghter version of the Model 377 at the same time, which differed from the airliner version by being used for cargo missions, with undernose weather radar and clamshell doors in the rear fuselage. The C-97 arrived just too late for the Berlin Airlift, but was used extensively in Korea. Like the Stratocruiser, only 60 dedicated C-97 transports were built: by the time the aircraft reached the USAF in numbers, the Lockheed C-130 Hercules was already in development.
Where the Stratofreighter would truly shine was as an airborne tanker: over 800 KC-97s would be built as the first purpose-built airborne tankers in the world. The clamshell doors were deleted, though cargo capacity was retained on the upper deck, giving the KC-97 a dual role. Fuel tanks were added to the lower deck, along with a station for the Boeing flying boom attached to the rear fuselage. The aircraft had to have separate fuel systems, as the KC-97 used piston engines and the jets it refueled would need a differing type. The use of piston engines was to prove problematic for the KC-97 as well: by the time it entered service in 1950, it was far slower than the jets it would need to refuel. The complicated Wasp Major engines were difficult to maintain, notorious for spraying oil at startup, and prone to catastrophic fires. At least two KC-97s were lost to engine explosions, something that had plagued the Model 377 as well. As the B-50 was retired in the early 1960s, J47 jet engines were removed and attached to Stratofreighters as the KC-97L variant.
The KC-97 could still be called a success, despite all of its problems and the fact that technology threatened to render it obsolete as soon as it entered service. Replaced in frontline service by the KC-135 Stratotanker, the KC-97 was relegated to Air Reserve and Air National Guard units in the mid-1960s, where it freed up KC-135s for service in Vietnam. Even with jet augmentation, the KC-97 was clearly obsolete by the 1970s, but a few KC-97Ls soldiered on until 1978, when it was finally withdrawn from service. A few briefly served with the Spanish Air Force during the 1970s, while Israel modified theirs to essentially KC-97 standard and utilized them in the Yom Kippur War of 1973.
52-2697, the KC-97 seen here, was the first KC-97G to be converted to L standard. It had served with the frontline USAF as a KC-97G, but after conversion, it was transferred to the 126th Air Refueling Group (Illinois ANG), assigned to Chicago-O'Hare International Airport. The 126th flew the KC-97L from 1961 to 1978. When the unit retired its Stratofreighters, the Grissom AFB Museum requested an aircraft, as the 126th ARG had used Grissom as a training base (the airspace at Chicago-O'Hare being rather crowded). 52-2697 was duly delivered to the base in 1979.
2697 has recently been repainted in anticorrosion gray, which is much easier on the aircraft than bare metal. Its markings are fairly anonymous, except for the SAC stripe carried around the fuselage. It is nearly impossible to see from this angle, but the boom at the rear of the aircraft is displayed as if deployed for refueling.
Boeing KC-97L Stratocruiser
The range of the B-29 Superfortress immediately interested Boeing in developing a passenger version for postwar use; this would make transatlantic and Hawaii flying routes economical for the first time. Since the standard B-29 fuselage would be inadequate for passengers, Boeing designers added a larger-diameter fuselage atop the old B-29 fuselage, resulting in a “double-bubble” appearance. The tail and engines of the B-50 advanced version of the Superfortress were adapted to what would become the Model 377 Stratocruiser. While only 55 Model 377s entered airline service, quickly eclipsed by the jet age, they were considered luxurious for their time, with the lower deck being used for airborne lounges or sleeping compartments, all in pressurized comfort—a first for the airline industry.
The USAF developed the C-97 Stratofrieghter version of the Model 377 at the same time, which differed from the airliner version by being used for cargo missions, with undernose weather radar and clamshell doors in the rear fuselage. The C-97 arrived just too late for the Berlin Airlift, but was used extensively in Korea. Like the Stratocruiser, only 60 dedicated C-97 transports were built: by the time the aircraft reached the USAF in numbers, the Lockheed C-130 Hercules was already in development.
Where the Stratofreighter would truly shine was as an airborne tanker: over 800 KC-97s would be built as the first purpose-built airborne tankers in the world. The clamshell doors were deleted, though cargo capacity was retained on the upper deck, giving the KC-97 a dual role. Fuel tanks were added to the lower deck, along with a station for the Boeing flying boom attached to the rear fuselage. The aircraft had to have separate fuel systems, as the KC-97 used piston engines and the jets it refueled would need a differing type. The use of piston engines was to prove problematic for the KC-97 as well: by the time it entered service in 1950, it was far slower than the jets it would need to refuel. The complicated Wasp Major engines were difficult to maintain, notorious for spraying oil at startup, and prone to catastrophic fires. At least two KC-97s were lost to engine explosions, something that had plagued the Model 377 as well. As the B-50 was retired in the early 1960s, J47 jet engines were removed and attached to Stratofreighters as the KC-97L variant.
The KC-97 could still be called a success, despite all of its problems and the fact that technology threatened to render it obsolete as soon as it entered service. Replaced in frontline service by the KC-135 Stratotanker, the KC-97 was relegated to Air Reserve and Air National Guard units in the mid-1960s, where it freed up KC-135s for service in Vietnam. Even with jet augmentation, the KC-97 was clearly obsolete by the 1970s, but a few KC-97Ls soldiered on until 1978, when it was finally withdrawn from service. A few briefly served with the Spanish Air Force during the 1970s, while Israel modified theirs to essentially KC-97 standard and utilized them in the Yom Kippur War of 1973.
52-2697, the KC-97 seen here, was the first KC-97G to be converted to L standard. It had served with the frontline USAF as a KC-97G, but after conversion, it was transferred to the 126th Air Refueling Group (Illinois ANG), assigned to Chicago-O'Hare International Airport. The 126th flew the KC-97L from 1961 to 1978. When the unit retired its Stratofreighters, the Grissom AFB Museum requested an aircraft, as the 126th ARG had used Grissom as a training base (the airspace at Chicago-O'Hare being rather crowded). 52-2697 was duly delivered to the base in 1979.
2697 has recently been repainted in anticorrosion gray, which is much easier on the aircraft than bare metal. Its markings are fairly anonymous, except for the SAC stripe carried around the fuselage. It is nearly impossible to see from this angle, but the boom at the rear of the aircraft is displayed as if deployed for refueling.