Flight stability

Engineers at Lehigh University have designed and successfully flight-tested a new control device that a pilot can use to tailor the lateral stability of aircraft.

Joachim Grenestedt, associate professor of mechanical engineering and mechanics, designed "canted tabs" that are attached to the ailerons, the movable control surfaces on the wings that are used to roll an aircraft upright.

Grenestedt said the tabs, which measure a few inches in length and width, rotate around an aluminium tube that is inserted into the aileron.

Three tabs were mounted on each aileron for the test flights, which took place at the National Test Pilot School (NTPS) in Mojave, California. The tabs used in these tests could be adjusted in flight by as much as 30 degrees.

When tested on an Aermacchi AM-3 "Bosbok" observation-reconnaissance plane with eight-foot-long ailerons, the tabs made the laterally unstable aircraft stable, Grenestedt said. "When the plane started to side slip, the tabs applied force to the ailerons, causing the plane to bank, or roll, and regain lateral stability."