[figure]
Figure 31. Tests of Olland-Cycle performance.
Hysteresis at any one temperature was the worst serious cause of the width of the envelope of curves. However, this error was minimized by the smoothness of the rotating cylinder and the continuous motion of the cylinder under the contact pen. Probably the necessary looseness of the bearings and the joining to the motor gear train had a great deal to do with the spread between different calibrations.
The maximum variation of any one calibration curve from the mean was about ±3 millibars.
The following recommendations are made for the use of the Olland-Cycle modulator:
(a) The modulator should be mounted inside the battery box and insulated so as to keep its temperature above -30°C.
(b) During the rapid-rising portion of the flight the accuracy of the data warrants reading only to the nearest one percent of a cycle, or about one millibar of pressure.
Tests on the sensitivity of Olland-Cycle modulators indicate that although the accuracy is limited as indicated above, small variations may be detected with the result that it is valid to read the pressure record to the nearest tenth of one percent of one revolution.
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