| 摘要 |
A gas gun has a charge chamber, an inlet valve to admit a charge of compressed gas to the charge chamber and either a plane or rifled barrel which communicates at its breech end with the charge chamber via a rotary outlet valve. Preferably the inlet valve is linked to the outlet valve so that closing of the inlet valve immediately precedes the opening of the outlet valve. The outlet rotary valve includes a frestoconical valve member which rotates within a complementary seat and has a radial bore which can connect two or more ports in the wall of the seat and is strongly biassed to the open position. The inlet and outlet valves may be combined in a three-way valve. In use a projectile is placed at the breech end of the barrel and the inlet valve is opened and the outlet valve closed. After compressed gas, preferably helium, has been introduced to the charge chamber to the desired pressure, the gun is fired by closing the inlet valve and immediately thereafter opening the outlet valve. The projectile expelled thereby has a velocity that is determined in part by the gas pressure in the charge chamber and may readily be varied by adjusting the gas pressure. Chamber pressures in the range 500 to 1500 psi lead to projectile velocities of the order 250-460 meter/second. The gas gun is especially useful in ballistic testing of, for example, personal armor. |
