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

It has to be noted however, that only one modified sensor was tested and this is notenough to definitely say that it performs better at colder temperatures compared to theoriginal - it might just be luck that this sensor performed correctly. It is possible to saythough, that we are very confident that the modified sensor does not lose contactdown to -100C. I recommended that further modified sensors should be tested tocheck for any manufacturing variations that affect low temperature performance.Both sensors are of a contact design however, and although the modified one doesperform well at cold temperatures it is possible it could lose contact for reasons otherthan icing, for example the brush might deform in the cold temperatures. Theexpected lifetime of the modified sensor is 50 million cycles minimum which is muchmore than it will ever have to endure on Zephyr, but ultimately it is recommended thata non contact sensor should be used, for example a magnetic sensor.54