0018933 on the first two shots. 2-3-5 Rocket Development. The project cloud sampling rocket (see Section 2.2.1) was a new one of complex design. The main motor had been used previously on the ASP (atmospheric sounding projectile) and the sustainer motor on the RTV (reentry test vehicle), but the nose cone and associated equipment had not been used as a componentof a rocket before. Development work on 2 similar sampling device had been done during Operation Plumbbob, andat the end of the operation a satisfactory unit for land recovery had evolved. After Plumbbob, Project 21.3, Task Unit 2, was set up for the purpose of developing a sea recovery version ; of the rocket for Operation Hardtack. When Project 2.8 was established, the existing rocket contracts were extended to provide additional units for use on this program. Because of the experimental nature of the rocket, the sponsors of this work, UCRL, assessed the probability of obtaining any rocket data as being of the order of 50%, The development problems were the responsibility of Project 21.3, bat a review of their work at the Eniwetok Proving Grounds is of interest since a large portion of Project 2.8 was directly dependent on the availability of@ suitable rocket-borne cloud sampler. This review will also serve to provide an explanation of the circumstances which led to the cancellation of the rocket experiment prior to Shot Oak, sye Std Phit GAN BRE: Gd