Quad (figure skating)
A quad, or quadruple, is a figure skating jump with at least three but less than four revolutions. Most quadruple jumps have 3 1/2 revolutions; the quadruple Axel has 4 1/2 revolutions, although no figure skater to date has completed this jump in competition. The quadruple toe loop and quadruple Salchow are the two most commonly skated in the discipline. Quadruple jumps have become increasingly common among World and Olympic level men's single skaters, to the point that not having one in a program has come to be seen as a severe handicap. The first person to land a ratified quadruple jump in competition was Canadian Kurt Browning in 1988. In 2002, Miki Ando became the first woman to do so, and she remains one of only two women to have landed a ratified quadruple jump in competition.
Delta wing
Triangular stabilizing fins for rockets were described as early as 1529-1556 by Conrad Haas and in the 17th century by Kazimierz Siemienowicz. A true lifting wing in delta form did not appear until 1867, when it was patented by J.W. Butler and E. Edwards in a design for a dart-shaped rocket-propelled aeroplane. This was followed by other proposals, such as a biplane version by Butler and Edwards, and a jet-propelled version by the Russian Nicholas de Telescheff.