An Cosantóir

www.military.ie the defence forces magazine | 19 be measured and accounted for or there will be an adverse affect on the fire-control solution. Periodic tilt- and-alignment checks will be carried out by the Naval Ordnance Section throughout the life of the ship and the error will be reduced and refined. The bedding-in shoot was also used to validate the operation and timing of the loading, recoil and ejection mechanisms. LÉ Samuel Beckett then returned to the Naval Base where NS ordnance personnel conducted the tilt-and-alignment measurements and tabulated the results. The three Danbuoy ranges then became the next focus of the trial which consisted of 24 firing 'runs' at three ranges. Warmers were fired at intervals as necessary to eliminate cold-barrel correction requirements. For each of the three ranges, eight rounds of 76mm HE were fired. (HE was selected to maximise the plume at impact for observation purposes.) All rounds were from the same lot, which had a muzzle velocity of 898m/s (measured by the Ordnance Section during ammunition accep- tance tests at purchase). The choice of range for each run was randomised in order to minimise uncontrolled factors. (It would have been unsound, for the purposes of the statistical trial, to conduct all the runs at one range, prior to moving to the next.) Each run was fired as a single shot and no corrections were applied, since correcting fall-of-shot at this stage would have militated against the purpose of the trial. The gun was 'parked' between each run, although the servos and hydraulics were left running. The statistical trial was designed to test the consistency with which the fire unit would solve the fire-control problem. To this end, the fire unit was not permitted to retain point-of-aim information but required to re-calcu- late it, coming from the low-port to the firing position, for each shot. The targets were presented ran- domly at three different ranges. It was not grouping that was of interest here but rather, the stability, rapidity and reliability of the solution of the problem for each individual round. Each impact therefore represented an initial ranging shot, calculated from zero with no corrections applied. Fall-of-shot was reported over the net and recorded by observers and by radar on both LÉ Samuel Beckett and LÉ Roisin (positioned down- range at 90° to the line of fire). Shots at the furthest range, beyond the visible horizon, were recorded by AW139 on SeaFlir. The operational shoot, unlike the statistical trial, involved changing range and bearing. As the ship closed on the target an initial salvo of five rounds was fired from 3,420m, which impacted correct for line but over the target. Two subsequent single shots were corrected onto the target (from 3,130m and 2,790m), fol- lowed with a three-round burst for effect from 2,200m. The operational shoot demonstrat- ed that the initial solution (assessed during the statistical trial) could be corrected while the range and bear- ing to the target was rapidly chang- ing. As a combat shoot it provided reassurance of the system's opera- tional capabilities. Comprehensive coverage of the range was achieved using the navigation radars of P61 and P51. The moment of impact for each trial round was captured by four X- Band and S-Band radar 'screen grabs' and by the AW139's camera. These were ranked in order of clarity and the best for each run were enlarged and printed. The distance and bearing between target echo and splash echo was also measured. Records were maintained of all elements of the trial including the fire-control data, gun totes, voyage data, weather, posi- tions, observation forms, navigation traces and ballistics. Tables were populated with data such as times of flight, MPIs, ranges, and bearings, and all data was collated and presented in the final report. Operation Godot was a fine joint effort by the ships, Naval Ordnance Section, FORST, D Ord, the Air Corps, the Artillery Corps, and DoD, and on foot of this trial the NSWG recom- mended acceptance of the system to FOCNS. 20mm Rheinmettal cannon, ships secondary armament 76mm OTO Melara main armament, rate of fire: 85 rds/min - range: out to 14kms

• Cover