July 1968. 4to. (Project 1T02170A047, contract DA 44-177-AMC-316(T); Dynasciences Corporation report DCR-275.) [Prepared by Dynasciences Corporation, Blue Bell, Pa.] Includes bibliographic references.

Analytical methods are developed for determining the downwash environment generated by multirotor/propeller V/STOL aircraft configurations operating in ground proximity. These methods are utilized to compute rotor flow field and contaminant dust cloud characteristics (including particle density and size distributions) for the H-21, XC-142, X-22A, X-19A, and XV-5A aircraft. The effects of the contaminated atmosphere on pilot's visibility, ground equipment, and personnel are also determined for these aircraft. The theoretically predicted results are generally in good agreement with the limited test data. Additional full-scale test data are required to verify further the assumptions inherent in the theory.