miles is the Nike Cajun. This vehicle would allow more instrumentation and weight than the Arcon vehicle. However, the Nike Cajun motor cost is presently estimated at about $7, 500. The large sample sizes calculated for the rotorchute system indicate that a smaller rocket-borne sampler may be of interest for particular tests and for repetitive test programs. The Arcas rocket manufactured by Atlantic Research is capable of transporting a 12-pound payload to just over 200, 000 feet. of the missile is 100 inches and the burnout weight of the motor is 24 pounds. The maximum length This rocket should be capable of carrying a collector which would sample about 1/4 the amount indicated in the design calculation. the Arcas motor is about $850 in lots of 150 units. The cost of However, the cost of the payload would probably not be much less than for the Arcon. Nomenclature qi, Diameter of the particle microns H Altitude above sea level feet K Inertia parameter Kn Cunningham correction factor L Half width of individual impactor feet Maximum half width of impactor at blade tip inches P Absolute pressure (ib force) /(sq ft) r Distance along blade from center line feet To Radius of rotorchute or parachute Vp Velocity of air relative to the rotorchute blade ft/sec Vx Velocity of descent of rotorchute with forward motion ft/sec Wa Weight of air sampled lb force Wr Total weight of descending vehicle plus sampler lb force p Density of the air lb mass/cu ft Py Density of the particles lb mass/cu ft Po Density of air at sea level 0.0765 ib mass/cu ft B Absolute viscosity lb mass/ft sec max ‘ feet References 1. Air Force Cambridge Research Center, General Electric Missile and Space Vehicle Department, 2, Atlantic Research Corporation, Quarterly Progress Report No. 3. Atlantic Research Corporation, Quarterly Progress Report No. 2, ''Sampling the Upper Atmosphere for Particulate Matter," September 25, 1959 to March 25, 1960, Contract No. AT(30-1)-2404. “Atmospheric Model," December 1959. 1, "Sampling the Upper Atmosphere for Particulate Matter," June 15 to September 25, 1959, Contract No. AT(30-1)-2404.