Blog Technology Review has posted some details about the project scientists from Purdue University, who managed to upgrade the gun ping-pong balls, so that now their speed reaches 1, 24 Mach (speed of sound in air).
As is known, such a gun is the classical long pipe into which the ball, and the tube is sealed with a solid film on both sides. Then air is pumped from the pipe. If after this one of the pierced film, the ball will fly under the influence of the air at the speed of about 200 meters per second.
The authors decided to improve this unit so that the ball flew at a speed of not less than the speed of sound - 330 meters per second. To do this, they have made a few changes to the design: the camera was used memory pressure, but before the ball in a tube positioned Laval nozzle (pair of cones and a narrow bridge in the middle, is used in almost all rocket engines).
As a result, the ball flew at a speed of 406 meters per second, and its flight recorded speed video camera.