Plane:

The Douglas A-26 Invader (designated B-26 between 1948 and 1965) is an American twin-engined light bomber and ground attack aircraft. Built by Douglas Aircraft Company during World War II, the Invader also saw service during several major Cold War conflicts. A limited number of highly modified United States Air Force aircraft served in Southeast Asia until 1969. It was a fast aircraft capable of carrying a large bomb load. A range of guns could be fitted to produce a formidable ground-attack aircraft.

A redesignation of the type from A-26 to B-26 has led to confusion with the earlier and unrelated Martin B-26 Marauder,[3] which had already been withdrawn from service when the designation was reused.

Design and development:

The A-26 was Douglas Aircraft's successor to the A-20 (DB-7) Havoc, also known as Douglas Boston. Designed by Ed Heinemann, Robert Donovan, and Ted R. Smith,[4] the innovative NACA 65-215 laminar-flow airfoil wing of the A-26 was the work of project aerodynamics expert A.M.O. Smith.[5][6]

The Douglas XA-26 prototype (AAC Ser. No. 41-19504) first flew on 10 July 1942 at Mines Field, El Segundo, with test pilot Benny Howard at the controls. Flight tests revealed excellent performance and handling but engine-cooling problems led to cowling changes and elimination of the propeller spinners on production aircraft. During testing, the nose wheel was found to be structurally inadequate and strengthened.[7]

center of the column 'flipped', showing the gunner a limited view similar to the view the upper periscope was seeing. As he pressed the handles downward, and as the bead passed the centerline, the mirror automatically flipped, transferring the sight "seamlessly" to the lower periscope. The guns aimed in the approximate direction the periscope was aimed, automatically transferring between upper and lower turrets as required, and computing for parallax and other factors. While novel and sound in principle, the developers invested a great deal of time and effort in their attempts to get the system to work, delaying production. As might be expected, the complex system was difficult to maintain in the field