Volume 2 : 3 ratio of the volumes of the sphere and cylinder is credited to Archimedes. The volume of a sphere is the integral of an infinite number of infinitesimally small circular disks of thickness "dx". The calculation for the volume of a sphere with center 0 and radius "r" is as follows. The surface area of the circular disk is formula_10. The radius of the circular disks, defined such that the x-axis cuts perpendicularly through them, is or where y or z can be taken to represent the radius of a disk at a particular x value. Using y
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