Comparison of Boundary-Layer Transition Predictions Using Flight Test Data

Flight tests using a Fokker F100 aircraft equipped with a natural laminar  ow glove demonstrated that natural laminar  ow is feasible for transport aircraft with up to 130 passengers. Furthermore, the  ight tests generated a wealth of experimental data. These data have been evaluated with all known variations of the emethod. The aim of this investigation was to compare the different methods and to identify the one that yielded the best correlation. No clear winner turned up in our investigation; each method has its own merit. The envelope method, if based on a compressible stability theory with surface curvature effects, gives a valuable N-factor correlation. With this method, few pathological cases occurred. These were characterized by a measured transition behind the maximum of the computed N factors. Methods using the N-factor pairs (NTS, N b ) and (NTS, NCF) computed with incompressible or compressible stability theory without curvature effects are also suitable. With these methods, however, many pathological cases occur. A satisfactory correlation can only be obtained if the pathological cases are excluded.