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

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5.3 Zephyr CompetitorsThe two nearest competitors to the Zephyr UAV are the Global Hawk (manufacturedby Northrop Grumman) [21] and the Global Observer (designed by AeroVironment)[22]. The Global Hawk is already being used by the US Air Force for surveillance inboth Afghanistan and Iraq, and was also used to monitor the Californian wildfires inOctober 2007. The Global Observer is currently being developed and should be inproduction by 2011. Table 3 shows the specifications of the Global Hawk, GlobalObserver and Zephyr.Global Hawk Global Observer ZephyrMaximum Altitude 65,000 ft 65,000 ft 65,000 ftMaximum Payload 2000 lbs 400lbs 5 lbsPower SourceTurbofan engineLiquidhydrogenSolar-electric(jet engine)internal combustionEndurance 35 hours 7 days 3 monthsTable 3. Table showing the main specifications of Zephyr and its competitorsThe Global Hawk which has a huge capability for a payload can only fly for 35 hoursbefore having to refuel. For some applications this may not be a hindrance, but it rules64
it out for long endurance missions. Furthermore, at a cost of $35 million USD they arevery expensive as they are still very new. During the Iraq War seven Global Hawkswere used with two lost due to technical failures, although the manufacturers claimedthat this was due to the lack of trained staff and spare parts. It does however have afailure rate per hour flown of over 100 times that of the F-16 fighters also used in thewar.As it is on the market first it automatically has an advantage as it is a market leader inunmanned surveillance and reconnaissance missions and it can carry such a largepayload. On the other hand, not only is the price of one Hawk so large, but with therising cost of fuel and the publicity about global warming, the public may not behappy with their government spending taxes on these fairly unreliable UAVs.The Global Observer is still in its development stage like Zephyr and also uses anenvironmentally friendly method of flight. It is being designed as a communicationrelay and remote sensing UAV, however with its short endurance it would need to berefuelled weekly if it was to be used as a longer term telecommunications platform.Although it has a much larger payload capacity than Zephyr, its endurance isconsiderably smaller and thus is a limiting factor. It is much easier to replace thepayload with a much lighter one than it is to lengthen the time a hydrogen poweredUAV can stay up in the air for.Zephyr has the advantage against its nearest competitors as it can fly for a few monthswithout needing to be refuelled. It is cheap to buy (in comparison to its competitors)and cheap to run, so that even if one did was involved in an accident the cost of65
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Zephyr:A High Altitude Long Enduran
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AcknowledgementsI’d like to thank
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ContentsChapter 1 - Introduction an
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Chapter 1Introduction and Backgroun
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1.1 History of ZephyrZephyr is a li
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The Zephyr 5 project continued with
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airframe, with the main aim to impr
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1.2 Environmental IssuesDuring the
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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 54 and 55: The magnetic sensor seemed much mor
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: Infoterra have a project called Far
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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