set of films. On the other hand, failure of a clock or of a shutter or of a power source is equally ruinous. Natural cloud cover can kill the mission completely. The results of these cloud-rise studies are easily the best obtained to date. However, the basic plan fell short of complete fulfillment in several. important respects. 3.2.1 Equipment Failures. The most-serious failures were those of the special shutters in the modified K—-17C cameras. This is presumably caused by the lowtemperature operation and was not encountered before the operation because of the ‘closeness of the schedule. The failures manifest themselves in double exposures, underand over-exposures occurring in a sequence of properly exposed photos andin the shutterremaining open during film transport. The resulting photographs sometimes give partial information but result more frequently in gaps in the data. Fortunately, these gaps are sometimes filled by cameras in the other planes. This difficulty became less serious as the operation preceeded. The data-recording chambers in these cameras were usually well exposed and legible. On.two occasions when the camera v’2s operated at runaway speed (1.5 second picture in- terval versus the prescribed 20 second) the vibration caused complete loss of the chamber data. This difficulty was eliminated. : _ The compasscard in the recording chamber sometimes.gave.data which are obviously Inerror. (The plane's course swings around a.60 degreé arc, but the card shows an angular change in aimingof only 25 degrees.) It is understood thatlack of time prevented the coupling of this card to a gyr‘o~repeater and that the settings were putin. manually. . Owingto the pressureof time, the prescribed short~focal-length lenses were not ysed on the motion-picture cameras. The use of long lenses, together with the too-close positioning of the aircraft, limited the field of view to about a third of the prescribed dimensions. As a result, the cloud invariably ran out of field in two minutes orless. There were two cases of failure of the clocks in the Eclair cameras, owing to lowtemperature operation. The difficulty was remedied satisfactorily. 3.2.2 Failures Due to Aircraft Location. The aircraft were much too close to the point of detonation, for the purposes of Project 9.1, because of compromises with other experimenters using the same planes. The RB—36 plane was needed by Project 11 to begin sampling operations after the first 10 minutes. This requirement pulled the plane in tg a range of 50 nautical miles on every shot and resulted in too small a field of view for the cameras. The cloudwentout-of-frame in the K—-17C cameras at 4 minutes (Shot 1) to % minutes (Shot 4) and in the Eclairs at 1.5 to 3.7 minutes. An accompanying difficulty arose from the Program 11 wish to have the plane in the southeast quadrant—-there was not enough light once the fireball dimmed, so that exposure-times up to 4 seconds had to be used. The platform was not steady enough for such long exposures, and the pictures are blurréd and difficult to read. The C—54 planes were shared with Task Unit 9, which wanted to be as close as possible to the burst. The compromises adopted werecertainly unsatisfactory to them as well as to Project 9.1. The ships were placed in the right directions but were only 40 to 60 nautical miles from ground zero— so close that the useful period of observation was limited to 10 minutes or less. There were two exceptions on Shot 5, when the planes were at 90 and 100 miles and procured good photographs to 15 and 20 minutea respectively. 3.2.3 Failures Due to Navigation Errors. The position data supplied by the aircraft navigators are not as good as had been expected. Undoubtedly EG&G did not appreciate all 15 SECRET ame. ve emcees wee omen scadienetinioasicaiminiatetiabatnieaiea ne