The twisted airfoil (aerofoil) shape of an aircraft propeller was pioneered by the Wright brothers. The aircraft had a redesigned, thinner, inverted gull wing of laminar flow aerofoil section. The rotor blades were a symmetrical aerofoil around a load-bearing spar. Axial compressors rely on spinning blades that have aerofoil sections, similar to aeroplane wings. The twisted aerofoil shape of modern aircraft propellers was pioneered by the Wright brothers. Paper pilot gliders make use a curved-plate aerofoil shape for best performance. This is the basis of aerodynamics and the foundation of modern aerofoil theory. Glauert wrote numerous reports and memoranda dealing with aerofoil and propeller theory. A wing with a conventional aerofoil profile makes a negative contribution to longitudinal stability. The Challenger's wing has been referred to as being a modified NACA symmetrical aerofoil. A wing is a flat, horizontal surface, usually shaped in cross-section as an aerofoil. The classic aerofoil section wing is unstable in flight and difficult to control. As the season progressed the team experimented with fitting aerofoil 'wings' to the car. This creates an aerofoil enabling them to glide or more. This creates an aerofoil enabling them to glide 50 metres or more.