In an effort to determine the influence of atmospheric turbulence on the transition of natural laminar
flow (NLF) airfoils, such as those found on gliders, one of the first steps is to characterise the turbulence
of the lower atmospheric boundary layer. For this purpose measurements were performed using a
motorized glider (Grob 109b), outfitted with an instrumented wing glove. The possibility of duplicating
the measured turbulence spectra in a wind tunnel were also investigated by a project partner at the
University of Stuttgart, and comparisons will be drawn between the two situations. The extent to which
the e n method can be modified to predict transition is explored. This was followed by a study in which
the laminar-turbulent transition was delayed on the pressure side of the wing using two methods. The
first was to add momentum to the boundary layer, modifying the neutral curve of linear stability theory.
The second used active wave cancellation with dielectric barrier discharge (DBD) plasma actuators to
suppress Tollmien-Schlichting waves. Both methods were tested in the wind tunnel and the latter was
demonstrated in-flight.