Abstract: A projectile (10) arranged to be launched from a launcher (12), the projectile comprising a source of compressed gas (1) and control means (23) for controlling the release of the compressed gas, in which the control means (24) is arranged so as to release the compressed gas in response to the launching of the projectile (10) from the launcher (12). Typically, the control means (24) is a valve, arranged such that the application of gas pressure from the launcher (12) is required in order to release the compressed gas, but the application of gas pressure must abate before the compressed gas is released. Thus, the compressed gas may only be released once the projectile (10) has cleared the launcher (12).