Accession Number : AD0428819


Title :   THEORETICAL STABILITY DERIVATIVES FOR A DUCTED PROPELLER.


Descriptive Note : Interim rept.,


Corporate Author : ITEK CORP PALO ALTO CALIF VIDYA DIV


Personal Author(s) : Kriebel,A R


Report Date : 18 Oct 1963


Pagination or Media Count : 1


Abstract : Static force and moment coefficients at angle of attack and their dynamic pitching derivatives are given for an isolated ducted propeller. These result from a potential flow analysis which is based upon Fourier expansion of the vorticity distribution. The analysis offers a valid technique for combining existing theory for ring wings at angle of attack and ducted propellers in axial flow. The propeller is represented as a uniformly loaded actuator disk and the effects of duct chord-to-diameter ratio, circular arc camber, taper, and thickness are shown for the duct coefficients and their pitching derivatives. The predicted thrust ratio of duct to disk for hovering flight is only slightly less than the asymptotic value of unity for thin cylindrical ducts with chord-to-diameter ratio greater than one half. For either hovering or axial flight, the duct thrust, the thrust ratio, and the propulsive efficiency all increase with duct chordto-diameter ratio, with outward taper downstream, with inward circular arc camber, and also with duct profile thickness if the actuator disk is located in the most favorable position in the duct where the internal cross-sectional area is minimum. (Author)


Descriptors :   *SHROUDED PROPELLERS , THRUST , VERTICAL TAKEOFF AIRCRAFT , HOVERING , AXISYMMETRIC FLOW , RING WINGS , STABILITY , ANGLE OF ATTACK , PITCH(MOTION) , MATHEMATICAL PREDICTION , AERIAL PROPELLERS


Distribution Statement : APPROVED FOR PUBLIC RELEASE