This important Department of Defense document, issued by the Office of the Secretary of Defense, presents a comprehensive study of the reliability of Unmanned Aerial Vehicles (UAVs). The combined U.S. military UAV fleet (Predators, Pioneers, and Hunters) reached the 100,000 cumulative flight hour mark in 2002. This milestone is a good point at which to assess the reliability of these UAVs. Reliability is at the core of achieving routine airspace access, reducing acquisition cost, and improving mission effectiveness for UAVs. Although it has taken the fleet 17 years to reach the 100,000 flight hour milestone, this study is the first comprehensive effort to address formally the reliability issue for these increasingly utilized military assets. The results presented are based primarily on actual flight operations data and augmented by in-house reliability assessments performed by individual UAV programs and contractors. Section 2 focuses on the military UAV platforms currently in service with the Air Force (Predator), Army (Hunter), and Marine Corps (Pioneer). It also presents discussions on developmental UAV systems including the Global Hawk and Shadow. This study compares not only the traditional metrics of reliability engineering (availability, mishap rate, and mean time between failure), but also presents the failure modes which have driven these metrics to their current levels. Section 3 compares U.S. UAV reliability to that of foreign UAVs and U.S. manned aircraft. Two conclusions are immediately apparent. First, U.S. and foreign (Israeli) UAVs share virtually identical percentages of failure modes. Second, the proportions of human error-induced mishaps are nearly reversed between UAVs and the aggregate of manned aircraft, i.e., human error is the primary cause of roughly 85% of manned mishaps, but only 17% of unmanned ones. Effects of design, weather, and aerodynamic anomalies are also examined in Section 3. Interesting trends due to one such effect – low Reynolds number flight – are presented as a poorly understood contributor to the poor flying qualities, and perhaps mishaps, of some smaller UAV systems. In analogy, where the airliner sees air molecules as many ping pong balls, small UAVs see them as a few beach balls. Areas for research are proposed to further understand, and circumvent, these effects. Section 4 of this study highlights technologies that exist in both aerospace and nonaviation related disciplines that can offer potential solutions to some of the more prevalent reliability “Achilles heels” of UAV platforms. From propulsion to human machine interactions, new methods, procedures, hardware, and software can target current failure modes which lie at the core of the majority of UAV mishap rates, unavailability, and MTBF statistics. In some cases where cost, size, and weight are of particular sensitivity to a UAV system, there exists commercial or government-off-the-shelf technology that may be able to provide affordable, short term solutions until some of the advanced technologies are available. Based on the reliability data and system information, this study concludes with recommendations in Section 5. Implicit within these recommendations is the conclusion that high reliability is not an elusive goal attainable by only the most sophisticated manned aircraft. The report contains 24 figures and 27 tables.
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Book Description Progressive Management, 2005. Ring-bound. Book Condition: Brand New. 73 pages. 11.20x10.40x0.80 inches. In Stock. Bookseller Inventory # 1422000982