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Within the ELFIN I program, flight tests using a Fokker FIDO aircraft equipped with a naturallaminar-flow glove demonstrated that natural laminar flow is feasible for transport aircraft with up to 130 passengers. Furthermore, the flight tests generated a wealth of experimental data. These data have been evaluated with all known variations of the e^-method within the ELFIN II program. The aim of this investigation was to compare the different methods and to identify the best. No clear winner turned up in our investigation; each method has its merit. The envelope method, if based on compressible stability theory with surface curvature effects, gives a valuable TV-factor correlation. With this method, few "pathological" cases occur. These are characterized by a measured transition behind the maximum of the computed TV-factors. Methods using the TV-factor pairs (TVTs,TVg) and (NTS,NCF) computed with incompressible or compressible stability theory without curvature effects are also suitable. With these methods, however |
