Book Description

In most of the conditions analyzed, the computed bending moments were found to be in good agreement with the measured moments. The agreement between computed and measured torsion moments, however, was poor, indicating that improvements are required in the mathematical model as far as the torsional properties are concerned. (These may include the introduction of the control system degrees of freedom in the model.) Comparison of measurements with airloads obtained with the Cornell program shows good agreement of the variations of the airloads over the azimuth. At the lower forward speeds the rotor wake can be represented by a set of ring vortexes. An urgent need exists for a method for predicting wake deformation and for programming this method. Torsional responses are important in the computation of airloads. A rotor trim procedure included in a rotor loads program has been shown to be useful in the prediction of rotor loads. Based on the results obtained for chordwise bending moments, the relationship between normal force coefficient and chord force coefficient used in Lockheed Program I should be reexamined, particularly in high angle-of-attack areas. Such investigation may result in improved estimates of drag coefficients.