曝光台 注意防骗
网曝天猫店富美金盛家居专营店坑蒙拐骗欺诈消费者
The Dull
B-2 crews flew 30-hour roundtrip missions from Missouri to Serbia during 34 days of the Kosovo conflict in 1999. The normal two-man crews were augmented with a third pilot, but even so, fatigue management was the dominant concern of unit commanders, who estimated 40-hour missions would have been their crews’ maximum. The post-Kosovo RAND assessment states “…the crew ratio of two two-man crews per aircraft might need to be increased to four crews or else provisions made [for foreign basing.] A serious limiting factor…is that doubling the B-2’s crew ratio would require either doubling the number of training sorties and hours flown by the Air Force’s limited B-2 inventory or reducing the number of sorties and flying hours made available to each B-2 crew member—to a point where their operational proficiency and expertise would be unacceptably compromised.” Contrast this short term imposition on crew endurance with the nearly continuous string of day-long MQ-1 missions over Afghanistan and Iraq that have been flown by stateside crews operating on a four-hour duty cycle for nearly two years.
The Dirty
The Air Force and the Navy used unmanned B-17s and F6Fs, respectively, from 1946 to 1948 to fly into nuclear clouds within minutes after bomb detonation to collect radioactive samples, clearly a dirty mission. Returning UA were washed down by hoses and their samples removed by cherrypicker-type mechanical arms to minimize the exposure of ground crew to radioactivity. In 1948, the Air Force decided the risk to aircrews was "manageable," and replaced the UA with manned F-84s whose pilots wore 60-pound lead suits. Some of these pilots subsequently died due to being trapped by their lead suits after crashing or to long term radiation effects. Manned nuclear fallout sampling missions continued into the 1990s (U-2 Senior Year Olympic Race).
The Dangerous
Reconnaissance has historically been a dangerous mission; 25 percent of the 3rd Reconnaissance Group's pilots were lost in North Africa during World War II compared to 5 percent of bomber crews flying over Germany. When the Soviet Union shot down a U.S. U-2 and captured its pilot on 1 May 1960, manned reconnaissance overflights of the USSR ceased. What had been an acceptable risk on 1 May became unacceptable, politically and militarily on 2 May. Although this U-2 and its pilot (Francis Gary Powers) were neither the first nor the last of 23 manned aircraft and 179 airmen lost on Cold War reconnaissance missions, their loss spurred the Air Force to develop UA for this mission, specifically the AQM-34 Firebee and Lockheed D-21. The loss of seven of these UA over China between 1965 and 1971 went virtually unnoticed. Thirty years later, the loss of a Navy EP-3 and capture of its crew of 24 showed that manned peacetime reconnaissance missions remain dangerous and politically sensitive. Other historically dangerous missions that appear supportable with UAS are SEAD, strike and portions of electronic attack. The highest loss rates to aircrew and aircraft in Vietnam and the Israeli-Arab conflicts were during these types of missions. One of the primary purposes for the employment of UA is risk reduction to loss of human life in high threat environments. Assignment of these missions to Unmanned Combat Air Vehicles (UCAV) directly addresses the dangerous mission of attacking or degrading integrated air defense systems.
中国航空网 www.aero.cn
航空翻译 www.aviation.cn
本文链接地址：
无人机系统路线图 Unmanned Aircraft Systems Roadmap(17)
