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<br />173 <br /> <br />Cloud Production <br /> <br /> <br />Seeding with the flares using the Schweizer proved to <br /> <br /> <br />be feasible. The general procedure was to put the aircraft <br /> <br /> <br />into a standard rate turn with a diameter of about one mile <br /> <br /> <br />and fire a flare whenever the contrail length indicated <br /> <br /> <br />proper conditions and the aircraft was in an area where <br /> <br /> <br />it was permitted to seed. The cloud trails so nucleated <br /> <br /> <br />proved to be difficult to observe in the generally bright <br /> <br /> <br />conditions at the high altitudes where seeding was performed. <br /> <br /> <br />No successful clouds Were noted in the .1977 trials, <br /> <br /> <br />but in the 1978 trials, 5 out of 8 flights had successful <br />seedings. The 1977 flights were carried out over New <br />Mexico without ground observers. In 1978 ground observa- <br />tions were made on all but two flights. <br />In two 1978 cases at least, clouds were viewed from <br /> <br /> <br />the ground which were not observed by the pilot initially <br /> <br /> <br />because of lateral drifting, ~nfavorable viewing conditions, <br /> <br /> <br />and other clouds aloft. In retrospect, the pilot speculates <br /> <br /> <br />that he may have made clouds on several occasions in 1977 <br /> <br /> <br />which he was unable to see because they did not develop <br /> <br /> <br />immediately and which finally may have developed after he <br /> <br /> <br />had lost track of the seeded circle. The Schweizer is a <br /> <br /> <br />single-seater with no inertial guidance system and it requires <br /> <br /> <br />almost superhuman effort to fly it and keep track of a <br /> <br /> <br />certain patch of clear air~ at the same time, at 30,000 <br /> <br /> <br />feet' altitude. In one case the pilot observed no cloud <br />