Zephyr: A High Altitude Long Endurance Unmanned Air Vehicle ...

The sensor was powered using an external power supply and was controlled by aservo actuator. The servo was connected to the vane and could be controlledexternally to make the vane move and replicate the movements it would face onboardZephyr. The movement of the vane caused the brush to move along the resistive trackwithin the potentiometer casing thus changing the voltage output which could bemonitored outside the chamber. An oscilloscope was also connected to the sensor toenable and voltage to be seen on screen as well as on the voltmeter. This allowed anyvoltage spikes to be seen easily rather than having to be read from the voltmeter(Appendix 4).4.3 ResultsBoth tests were completed without any problems. The voltages recorded were asexpected and there was no spiking evident in either test at any temperatures. Theprevious sensor lost contact at -83C, -74C and 70C but the modified sensor keptcontact at all times.Although the testing was supposed to be conducted at 50 mbar, there was a problemwith the chamber meaning that it could not get to a low temperature at such a lowpressure. It was decided that the temperature was the most important variable and thatincreasing the pressure by 50 mbar to 100 mbar would not affect the results greatly.The first test which was conducted in order to compare results with the previoussensor was mostly completed at 50 mbar (see Appendix 5).52