A4D (A-4) Skyhawk
The A-4 Skyhawk is a lightweight, single engine attack aircraft, with a design based on experience gained in the Korean War. The "Scooter" is probably one of the most famous attack aircraft ever designed. This short range attack and close support aircraft was originally intended for the US Navy and Marine forces. The design was a quick success, and Skyhawks continue to fly in air forces around the world. There are numerous models of the A-4 in use. All models have two internally mounted 20mm cannons, and are capable of delivering conventional and nuclear weapons under day and night visual meteorological conditions. The aircraft is a very compact design, with no wasted space. The structure is a conventional all metal semimonocoque type. Fitted with automatically operated wing slats and hydraulically operated split flaps. Folding wings were not provided.
Configuration of the aircraft is characterized by a cropped delta wing of 33° sweepback mounted in the low position on a short, stubby fuselage with a large vertical tail and dorsal surface. The horizontal tail is mounted part way up the vertical fin just above the wing chord plane extended and consists of an electrically actuated stabilizer and hydraulically powered elevator. The hydraulically actuated rudder is of a unique design, consisting of a single central skin with external riblike stiffeners. According to the interesting account of the development of the A-4 given in reference 164, this design feature was found to offer a solution to problems of rudder buffet or buzz.
Two inlets mounted high on the fuselage just ahead of the wing supply air to the single Pratt & Whitney turbojet engine of 8500 pounds thrust. The boundary-layer diverters located Just ahead of the inlets. The long landing-gear struts were dictated by clearance requirements for large stores carried beneath the wings on either side and between the main landing-gear legs. A braking chute was provided for use at shore-based landing facilities.
For simplicity, the wing of aspect ratio 2.91 was built as a single unit with continuous top and bottom skins. it was so small that no folding was necessary for storage and movement on the aircraft carrier, an unusual feature in a Navy aircraft. Automatic leading-edge slats and trailing-edge split flaps were provided for lift augmentation. Outwardly extending speed brakes were mounted on either side of the rear of the fuselage.
The Skyhawk is capable of carrying literally hundreds of combinations of external stores including fuel tanks, both conventional and nuclear bombs, rockets, and Sidewinder missiles. Armament consists of two 20-mm cannons, one of which is mounted in each wing root.
The Skyhawk has a remarkably low gross weight of 18,311 pounds but can deliver a weapons load of 2,040 pounds at a mission radius of 680 miles with two 300-gallon external tanks; unrefueled ferry range is 2130 miles. Maximum speed of the aircraft is 673 miles per hour (Mach 0.88) at sea level, and cruising speed is 498 miles per hour. Ceiling is just over 40 000 feet. Certainly, the aircraft has an impressive performance for a lightweight attack aircraft.
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