The B-2 bomber racked up an impressive combat debut in the Kosovo bombing campaign. Six B-2s, operating from Whiteman air force base in the American Midwest, flew 49 sorties during Allied Force. While three missions were recalled, and one was a non-combat operation, 45 aircraft dropped 682 bombs, although four percent failed to work. According to the air force, B-2 bombs " damaged a higher percentage of their targets than any other aircraft participating in combat operations." But there's a catch. The maintenance load for these aircraft is enormous, particularly for the radar absorbing material it is covered with. As a result, only 40-50 percent of the B-2s are ready to fly missions at any given time. The aircraft was designed to be available 60 percent of the time, even though the heavy maintenance load was known all through the aircraft's development. All that time in the hanger getting fussed over has caused many to tag the B-2 a Hanger Queen (slang for a troublesome aircraft that's always under repair.)