The Method of Mechanical Theorems convenient to use a little bit of coordinate geometry. If a sphere of radius 1 is placed with its center at "x" = 1, the vertical cross sectional radius formula_2 at any "x" between 0 and 2 is given by the following formula: The mass of this cross section, for purposes of balancing on a lever, is proportional to the area: Archimedes then considered rotating the triangular region between "y" = 0 and "y" = "x" and "x" = "2" on the "x"-"y" plane around the "x"-axis, to form a cone. The cross section of this cone is a circle
Eurocopter X³ et de l’espace in 2014 for public display. The Airbus RACER "(Rapid And Cost-Effective Rotorcraft)" is a development revealed at the June 2017 Paris air show, final assembly will start in 2019 for a 2020 first flight. Cruising up to , it aims for a 25% cost reduction per distance over a conventional helicopter. Eurocopter X³ The Eurocopter X³ "(X-Cubed)" is an experimental high-speed compound helicopter developed by Airbus Helicopters. A technology demonstration platform for "high-speed, long-range hybrid helicopter" or H³ concept, the X³ achieved in level flight on 7 June 2013, setting an unofficial helicopter speed record. In June