Measuring projectile’s end velocity (1972)
This measuring device determines projectile speeds at the location of an imaginary target at a large distance from the cannon (1 to 2 km). The spread of the projectiles at this distance is large. The system is therefore designed with a large detection field: a diameter of 8 metres and a flight height of a 105 mm projectile of 10 metres. This measuring device was built in collaboration with TNO-TPD. The system was handed over to the Commission of Trials of the Royal Netherlands Army in 1972.
The measuring device consists of two optical units. Each unit contains three optical detectors with contiguous fan-shaped detection fields and an amplifier unit. The three optical detectors per unit are necessary to obtain a detection plane with an approximate 90° opening angle. The two optical units are provided with directional means to arrange the two detection planes in parallel. The units are placed at a distance of for instance 20 metres of each other. The flight time of the projectile is measured with two time-interval meters (counters t1 and t2) (see diagram). When the projectile passes the first photocell detector, the leading edge of the obscuration signal starts counter t1 and its trailing edge counter t2. When the second photocell detector is passed, counter t1 is stopped by the leading edge of the blackout signal and counter t2 on the trailing edge. The counter values can then be automatically added to the telex by the printout converter (PRICO), with the clock time and a serial number added. The projectile speed can be determined from the measurement data.
The printout converter or PRICO supplies the measurement data to a telex. The projectile velocity can be determined from the measurement data.