XB-53 / XA-44
The forward swept wing XB-53 was designed by Convair based on German research data captured in WWII. The benefits of forward swept wings have long been understood. Both forward and aft swept wings yield significant drag reduction in the transonic speedrange. Since air flows inboard on forward swept wings, unlike the outboard flow on traditionally swept wings, the forward swept wings’ tips remain unstalled at higher angles of attack, retaining maneuverability and controllability. However, until composite materials became readily available in the early 1970s, the forward-swept-wing design suffered from weight penalties in utilizing the conventional aluminum structure.
The advantages of the Forward-SweptWing (FSW) design have been recognized since World War II, with Germany taking the most active role in producing several forward-swept-wing aircraft designs. Germany's first design was the Junkers JU287 Bomber. Several designs made forays into FSW technology. The sculpted, minimalist contours of the unflown Bugatti R-100 of 1937 included a modestly forward swept wing planform created by veteran Belgian designer Louis de Monge. His earlier designs had claimed three sanctioned speed records, and in the late 1930s, it is said de Monge wanted to best the speed claims of the emerging Messerschmitt fighter team. The tandem-engine R-100 did not fly in France before occupation by Germany caused the aircraft to drop out of sight until after the war, when it was no longer a speed contender in the jet age.
During World War II, the U.S. Army Air Forces at Wright Field, OH, studied a FSW concept advocated by designer George Cornelius, who had earlier designed a light aircraft, the “Mallard,” having a forward swept wing, that first flew in August 1943, showing some promise for further development. Dr. Courtland Perkins, later to become Assistant Secretary of the U.S. Air Force (USAF), reviewed Cornelius’s ideas, and in a memoir Dr. Perkins recalled: “The characteristics of the sweptforward wing would be very good with a strong possibility of having a stable airplane at high angles of attack.”
Though the Cornelius glider did not lead to production, its concept sparked interest and research at Wright Field. A theoretical aircraft design was created by the Design Branch at Wright Field to enable a wind tunnel model to be constructed. The FSW model had a circular fuselage with a vertical fin. Ailerons were on the outboard portions of the wings and elevators occupied the inboard sections. Tested in Wright Field’s 5-foot test section wind tunnel, the radical model “confirmed all our projections,” Perkins recalled. “It had good longitudinal and lateral control powers, had excellent directional stability and it was longitudinally stable up into the stall.”
The model led to the construction of two manned FSW gliders, the Cornelius XFG-1, which were described as “easy and pleasant to fly,” with one possible difficulty being stall/spin recovery, which the National Advisory Committee for Aeronautics’s (NACA’s) Langley Research Laboratory spin tunnel tests had indicated.
The XB-53 was originally intended as an attack aircraft to be known as the XA-44. The wings would be forward swept at a 30 degree angle with an 8 degree dihedral. The wing, which also functioned as the horizontal stabilizer, was situated at the aft portion of the fuselage. Pitch and roll adjustments were made with wing mounted control surfaces. The XB-53 featured elevators on the inboard wing and ailerons on the outboard. The wingtips also functioned as variable incidence control surfaces. It's turbojet engines were concealed in the fuselage.
The XB-53 had a weight capacity of 60,000 lbs. and a range of 2000 miles. It's three General Electric J35 engines propelled the craft to 580 mph and allowed it to carry up to 12,000 lbs. of bombs.
Funding for the XA-44/XB-53 project originally came from development funds for the XB-46. The Air Force debated canceling the XB-46 altogether but eventually a compromise was struck. Corvair built one stripped down XB-46 and planned on building two XA-44s instead of the XB-46s left on the contract.
Although the two aircraft were ordered (S/N 45-59583/4) the program was scrapped before they could be completed and delivered.
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