Forward-swept wing

This allows full aileron control despite loss of lift, and also means that drag-inducing leading edge slots or other devices are not required.

Such an increase in tip lift under load causes the wing to tighten into turns and may result in a spiral dive from which recovery is not possible.

At large angles of sweep and high speeds, in order to build a structure stiff enough to resist deforming yet light enough to be practicable, advanced materials such as carbon fiber composites are required.

Composites also allow aeroelastic tailoring by aligning fibers to influence the nature of deformation to a more favorable shape, impacting stall and other characteristics.

Composite materials allow aeroelastic tailoring, so that as the wing approaches the stall it twists as it bends, so as to reduce the angle of attack at the tips.

This ensures that the stall occurs at the wing root, making it more predictable and allowing the ailerons to retain full control.

An early example to fly, in 1940, was the Soviet Belyayev DB-LK, a twin-boom design with forward-swept outer wing sections and backwards-swept tips.

The Mallard was powered by a single engine, but it was followed by the Cornelius XFG-1 prototypes, which were flying fuel tanks, unpowered and designed for towing by larger aircraft.

He recognised many of the advantages that forward sweep offered over the backwards-swept designs then being developed, and also understood the implications of aeroelastic bending and yaw instability.

Flight tests on this and later variants confirmed the low-speed advantages but also soon revealed the expected problems, preventing high-speed trials.

These included the Convair XB-53 supersonic bomber and forward-swept variants of the North American P-51 Mustang, Bell X-1 rocket plane and Douglas D-558-I.

In 1954, Wocke returned to the German Democratic Republic, moving to West Germany shortly afterwards and joining Hamburger Flugzeugbau (HFB) as their chief designer.

In the late 1970s, DARPA began investigating the use of newer composite materials to avoid the problem of reduced divergence speed through aeroelastic tailoring.

[6] Advances in thrust vectoring technology and a shift in air combat tactics toward medium range missile engagements decreased the relevance of a highly agile fighter aircraft.