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

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The magnetic sensor seemed much more feasible as it did not have any delicate parts(figure 12). The magnetic sensor uses the Hall Effect by having a vane attached to onemagnet and as it is moved by the wind it causes the magnet to move and thus the HallVoltage to change. Although this had clear advantages as it did not have any criticalparts that had to be in contact (unlike the potentiometer), it was not compatible withthe electronics onboard Zephyr. It was decided that although a magnetic sensor was agood idea in the long run, it was not feasible to change the electronics on the aircraftat the present time.Figure 12. Diagram to show the magnetic sensor. The wind vane would be attached tothe brown magnet which would be placed inside the silver pod [12]Other magnetic sensors were investigated, but they were all too big and too heavy forZephyr. A sensor has to be small so it can be placed on the aircraft without affectingthe aerodynamics, and light not to add significant weight onto Zephyr.There was another possible solution which involved using the original sensor butheating it in order to keep it within its certified temperatures. It was decided however48
that due to the limited power available onboard Zephyr from the solar panels, thesensor should be modified and not heated.I finally decided that it was best to use the existing sensor but to modify it in order toprevent it failing at cold temperatures. After many discussions with themanufacturers, SpaceAge Control Inc, it was decided to remove the lubricant betweenthe track and the brush, and change the lubricant on the bearings within the brush tolow temperature lubricant. This would prevent the vane from freezing and not movingand it was hoped that this would solve the problem. Once the new improved vane wasdelivered it had to be tested in a thermal chamber to ensure that it would work at thecold temperatures.49
Page 1 and 2:
Zephyr:A High Altitude Long Enduran
Page 3 and 4: AcknowledgementsI’d like to thank
Page 5 and 6: ContentsChapter 1 - Introduction an
Page 7 and 8: Chapter 1Introduction and Backgroun
Page 9 and 10: 1.1 History of ZephyrZephyr is a li
Page 11 and 12: The Zephyr 5 project continued with
Page 13 and 14: airframe, with the main aim to impr
Page 15 and 16: 1.2 Environmental IssuesDuring the
Page 17 and 18: order to function, they may not thu
Page 19 and 20: 1.2.3 Cosmic RaysCosmic rays are en
Page 21 and 22: wind speeds. This is to ensure that
Page 23 and 24: crystalline silicon cells and can b
Page 25 and 26: which are then insulated. In order
Page 27 and 28: motion of the aircraft including ro
Page 29 and 30: Within the portable cabins the crew
Page 31 and 32: Simple payloads instructions withou
Page 33 and 34: In the event that the wing does not
Page 35 and 36: Graph 4 shows radiosonde density da
Page 37 and 38: 3.2 NIOSH Lifting EquationThe hand
Page 39 and 40: Variable Description MultiplierD (c
Page 41 and 42: Using the given values, the corresp
Page 43 and 44: 3.3 Airspeed SensorThe current airs
Page 45: 12VSensorPCBZenerDiodeFigure 8. Dia
Page 48 and 49: 3.4 PayloadThe payload is the carry
Page 50 and 51: where λ is the wavelength, c is th
Page 52 and 53: 3.5 Angle of Attack SensorThe angle
Page 56 and 57: Chapter 4Angle of Attack Experiment
Page 58 and 59: The sensor was powered using an ext
Page 60 and 61: It has to be noted however, that on
Page 62 and 63: experience the atmospheric conditio
Page 65 and 66: 5.2.1 Aerial PhotographyThe most co
Page 67 and 68: meaning that these cameras can be u
Page 69 and 70: Infoterra have a project called Far
Page 71 and 72: it out for long endurance missions.
Page 73 and 74: Figure 18. QinetiQ’s Zephyr5.4 Co
Page 75 and 76: where it is needed rather than havi
Page 77 and 78: Appendix 3Schematic diagram of the
Page 79 and 80: Appendix 5The results table for the
Page 81 and 82: BibliographyQinetiQ Documents[1] St
Page 83: [19] Encyclopedia Britannica, 2004.
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