 As the wing swept back, the root also slid forwards, maintaining the centre of lift in a constant position.A variable-sweep wing of this sliding type was flown on the prototype Grumman XF10F Jaguar in 1952, however the F10F proved unacceptable for other reasons and never entered service.From the late 1940s, British engineer L. E. Baynes studied variable sweep, developing a method of varying the tail geometry as well in order to stabilise the centre of lift.