Wednesday, September 27, 2017

F8U Two-Position Wing

The F8U was one of the few production airplanes with a variable-incidence wing, with the wing raised for takeoff and landing to reduce the nose-highness of the fuselage for those flight conditions while still providing a wing angle-of-attack that maximized lift and therefore minimized takeoff and landing speed to meet carrier-basing limitations.

It was in part the result of Vought's experience with the F7U Cutlass and the Navy's dislike of its nose-high attitude on takeoff and landing. The F7U-3's radome, cockpit, and canopy had to be redesigned to provide adequate visibility over the nose before at-sea carrier landing qualification trials were authorized.
When Vought proposed what was to become the F8U, the need for low drag for maximum speed restricted the height of the canopy. The height of the landing gear, particularly the nose gear, was also to be minimized for various reasons, including weight reduction and to avoid problems experienced with the F7U's long nose landing gear. However, these two design stipulations were difficult to accommodate with the longer aft fuselage of a conventional tailed airplane with an afterburner.

The two side views in the following illustration are to the same scale with the main landing gear wheels and static ground line (approximately the landing attitude relative to the deck) coinciding. Note that the aft fuselage of the F8U would strike the deck with the nose raised only a little over five degrees.
The result was the incorporation of a two-position wing to allow for both adequate visibility over the nose for carrier landings and aft-fuselage clearance on touchdown.

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