0018933 2.2 INSTRUMENTATION The instrumentation for this project falls into two general classes: rocket-borne and aircraft-borne cloud samplers, Two types of aircraft, B-57D's and WB-50's, were used, 2.2.1 Rocket-Borne Cloud Sampler. The rocket, a 20 foot long unit, consisted of an air-sampling nose section, a two-stage propulsion unit and various items of auxiliary equipment (Reference 57). The air-sampling diffuser of the nose section was 36 inches long from the intake orifice to the filter. An additional 32 inches of length behind the filter was occupied by exhaust ports and auxiliary equipment. The extreme forward part of the rocket was a conical section 5 inches long which sealed the intake orifice prior to the time when sampling was begun. The orifice of the diffuser was 2 inches in diameter and the filter was 8-1/2 inches in diameter. An expansion from 2 inches to 8-1/2 inches in diameter in a length of 36 inches gave an expansion angle of 10 degrees, the maximum at’ which the flow would not separate from the diffuser walls, The filter was an 8 inch circle of matted cellulose fiber coated with stearic acid to help retain the particles. It was supported by a wire retaining screen. The inside wall of the diffuser was in the form of a revolved segment ef a circle 250 inches in radius and was parallel to the axis of the rocket at the erifice. Particles entering the sampling section were decelerated from about twice the sonic SAN BRUNO ERC 41 4