The Roswell Report: Fact vs. Fiction in the New Mexico Desert

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this switch a circuit is closed when the rate of descent exceeds 1/5 mb/minute, allowing ballast to flow. The record of Flight 97 indicates that good control was obtained for a four hour period using this switch. However, the instrument is so delicate and susceptible to temperature effects that its use is not advised.

## E. Flight Simulation

To make laboratory tests on the control equipment just described, a flight-simulation chamber has been built combining a bell jar and a temperature chamber. A drawing of the temperature chamber designed and built at New York University is shown in Figure 17. (Investigation of commercially sold chambers showed that the cost of purchasing a temperature chamber of the size desired would be prohibitive.) First designs called for the use of a freon refrigerating system; however, use of dry ice as a coolant proved to be more advantageous. This chamber, with its automatic control, can hold temperatures as high as $ + 1 0 0^{\circ} \mathrm{F} $ and as low as $ - 9 0^{\circ} \mathrm{F} $ within 50 for a period of several hours. Dry ice consumption at $ - 6 0^{\circ} \mathrm{F} $ is approximately 150 pounds for a 24-hour period.

LOWEST WORKING TEMP. -65° To -70°C ACCURACY OF TEMP CONTROL 0.5°C

Figure 17. Temperature control chamber.

It is possible, using a bell jar for flight-similitude studies, to arrange switches so that the vacuum pump is turned off and on at