Apart from its uniqueness, Concorde is seen as a pace-setter because all other attempts to design such aircraft have relied on its delta wing design.

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Each side of Demon's delta wing has one row of these slots in the upper part of its trailing edge and another on the lower part.

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Their final design of the QSST jet is reminiscent of Concorde in its delta wing shape, but with a number of unique features, including an "inverted V-tail" and tailored nose cone.

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Paper or not, Boeing is milking the image of the futuristic delta-wing design with huge posters on, for instance, the road from central London to Heathrow airport.

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