THE INFLUENCE OF SUPERSONIC AIRFLOW ON AERIAL PHOTOGRAPHY
Abstract
The influence of a turbulent boundary layer, as it affects refraction, dispersion, and scattering of light rays, was investigated as one of the phenomena that degrades photographic resolution. The investigation was experimental and consisted of making photographs of a resolution target through a supersonic wind tunnel with a high resolution camera (35mm film, f equals 135mm, 1:2.8). Short-duration flash or long-exposure incandescent illumination was used and photographs were made when the wind tunnel was operating and when not operating. Under experimental test conditions the system gave an average resolution of 380 lines/mm when the tunnel was not running and gave an average resolution of 302 lines/mm when the tunnel was operated with speeds of Mach 1.5, 2.0, and 2.5 and pressures corresponding to 30,000 ft and 50,000 ft altitude. The loss in resolution of approximately 80 lines/mm corresponds to a stochastic influence of a boundary layer of about 1/3-inch thickness on light scattering and as if produced through a medium with an inherent resolution limit of 1500 lines/mm. The results are in fair agreement with NACA results. It was concluded that photographic systems with a resolution up to 100 lines/mm and usual aperture ratios may not be disturbed greatly by a thin turbulent boundary layer.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1961
- Accession Number
- AD0262000
Entities
People
- Hermann R. Mestwerdt
- Werner Rambauske