XF91 Thunderceptor
The xf91 design was one of two swept-wing modifications based on the original Republic F-84 Thunderjet, the other being the Republic F-84F Thunderstreak which was developed later.
A unique feature of the Thunderceptor was its unusual inverse tapered wing, in which the chord length increased along the wing span from the root to the tip, the opposite of conventional swept wing designs.
The wings were built to have considerably more chord at the tip than root, allowing them to generate more lift. This neatly addressed the problem of Sabre dance by delaying the point of stall on the tip to that of the entire wing.
Another design change was the ability to vary the angle of incidence of the wing as a whole, tilting it up for during takeoff and landing. This allowed the fuselage to remain closer to level while landing, greatly improving visibility.
(The second prototype had a V tail)
J47-GE-7 jet and XLR-11-RM9 rocket engine
Max speed Mach 1.49
build 2 prototypes
Build in 1949, first flight 1951