An aircraft (e.g. transonic, unmanned) has a wing 3 defining upper 14 and lower 15 geometric surfaces meeting at the intersection with the airfoil chord 13. The aerofoil defines upper 19 and lower 20 aerodynamic surfaces meeting at the intersection with stagnation (attachment) line dividing airflow over upper and lower aerodynamic surfaces. The lower geometric surface adjacent the leading edge 11 has a roughness strip 22 with a step height of at least 50 microns (μm). The stagnation point moves downstream along the lower geometric surface with increasing lift through incidence to onset flow (angle of attack) and hence the roughness strip is on the lower aerodynamic wing surface when the aircraft flies at a load factor of 1g (e.g. cruise), but the step is located on the upper aerodynamic surface when the lift to weight ratio increases to 1.2g or more (e.g. during a dive, gust, buffet, manoeuvre). The step may trip a laminar boundary layer to become turbulent, causing predictable interaction with a shockwave 21. The step may be a groove, applique, tape, paint coat strip, joint, fasteners, zig-zaged or straight, continuous or broken line.
Aircraft wing roughness strip
2017-09-06
Patent
Electronic Resource
English
IPC: | B64C AEROPLANES , Flugzeuge |
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