Aerodynamic characteristics of an axisymmetric body undergoing a uniform pitching motion
By: by Lloyd H. Smith [and] Robert H. Nunn
Contributors: Nunn, R. H. (Robert H.); Naval Postgraduate School (U.S.)
Publisher: Naval Postgraduate School
Published: 1975
Place of publication: Monterey, Calif
Language: eng
Number of pages: 99
Subjects: Wakes (Fluid dynamics); Aerodynamics; Vortex-motion
Description: An experimental investigation was conduct3ed to determine the effect of a uniform pitching motion on a slender axisymmetric body while undergoing large excursions in angle of attack.  Force and moment measurements were obtained for a slender tangent-ogive/cylindrical body over a range of Reynolds numbers from 5 x 10 to 1.4 x 10 while varying the angle of attack from zero to 90 degrees and the pitch rate between zero and 281 degrees per second.  Smoke flow visualization studies were used as an aid in assessing wake vortex transitions.  The results of the investigation show that there is an increment of normal force directly attributable to the uniform pitching motion.  The incremental increase in the normal force is sufficient to cause significant errors in calculating body damping derivatives from static force measurements.  Distinct wake vortex transitions at approximately 20, 50, and 65 degrees were observed.  The effect of a uniform pitching motion shifts the angle of attack at which these wake vortex transitions occur, and can reduce the abruptness of those transitions. (
Notes: Title from cover.

"February 1975"--Cover.

"NPS-59Nn75021"--Cover.

Author(s) subject terms: Aerodynamics, missile, high angle-of-attack, vortex wake.

Includes bibliographical references (p. 95-97)

"Approved for public release; distribution unlimited."

Technical report; 1975.