Concept drawing for Defense Advanced Research Projects Agency's (DARPA) Quiet Supersonic Platform (QSP) program, circa 2007, <a rel="nofollow" class="external free" href="https://news.northropgrumman.com/news/releases/northrop-grumman-unveils-concept-for-quiet-supersonic-aircraft">https://news.northropgrumman.com/news/releases/northrop-grumman-unveils-concept-for-quiet-supersonic-aircraft</a>
Air Force Association, artist unknown
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