sin αst

LIST OF ATTACHMENTSALTERNATIVE AIRFOIL TEST
The charted results for profile B:
Figure J.8: Measured lift coefficient, drag coefficient and glide ratio for profile B
Profile A stalls at an angle of attack of 10�, while profile B stalls at 13�. Both profiles have
an optimum angle of attack of 4.5�, where the glide ratio is maximal. Profile A however has
a higher glide ratio and it is therefore considered the better of the two profiles.
The variation of the test results are primarily ascribed to uncertainties in the adjustment
of the angle of attack. Another factor that has contributed to the result variance is the lack
of stiffness of the test airfoil, which vibrated slightly during the performed tests, resulting
in fluctuating measurements of load.
The measured aerodynamic properties of profile A are added to the rotor design tool using
the method described in appendix D. Figure J.9 shows the lift coefficient, drag coefficient
and glide ratio for the airfoil in the angle of attack range of 0�-90�. The properties are de-
rived using Viterna and Corrigan (see appendix D) and with �opt of 4.5�, �st of 10 and Cd.max
= 1.11+0.018AS [16].
220