10,2 cm Mark 16
These guns appeared on these two ships after their completion in 1941. Jacob van Heemskerck originally had a main armament of 5.9 inch Mark 11 guns, but the needed fire control system couldn't be delivered. This type was very effective against air targets, but too light to be really useful in seabattles.
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| One of the twin 4-inch mounts aboard HMS Resolution in Gibraltar, 1939 |
| Gun specs | |
| Gun type | Mark 16 |
| Purpose | High Angle/Low Angle ( sea- and airtargets ) |
| Bore | 10,2 cm ( 4 inch ) |
| Classes used on | Jacob van Heemskerck |
| Isaac Sweers | |
| Date of design | 1934 |
| Date in service with RNN | 1941 ( commissioning Jacob van Heemskerck ) |
| Length | 40 calibers ( 4,84 m ) |
| Gunweight | 2,4 tons |
| Initial velocity | 2651 feet/sec |
| Rate of fire | 20 rounds minute |
| Shell specs | |
| Shell types | HE only |
| Shell weight | 35 lbs |
| Range ( max ) | 12000 meters @ 80 degrees |
| 16200 m @ 0 degrees | |
| Mount specs | |
| Mount type | Mark 19 |
| Mount armor | - |
| Mount weight | 14 tons |
| Elevation | -10 / +80 degrees |
| Train | 340 degrees ( +170 / -170 ) |
| Train method | Manual |
| Diagram | |
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| Twin 4 inch Mark 16 diagram ( click to enlarge ) | |
| A | Loading lamp |
| B | Percussion firing lever |
| C | Recuperator cylinder |
| D | Breech mechanism lever |
| E | Breech mechanism lever locking lever |
| F | Safe/fire lever |
| G | Semi-automatic gear link |
| H | Semi-automatic/quickfire changeover lever |
| I | Balance weight |
| J | Recoil cylinder compensating pipe |
| K | Training buffer |
| L | Fuze setting machine, Mark II |
| M | Follow fuze number |
| N | Fuze-setting handle |
| O | Ejector lever |
| P | Safety firing cam |
| Q | Safety firing rolling follower |
| R | Layer's footrest |
| S | Elevation receiver |
| T | Star shell datum spirit lever |
| U | Layer's monocular |
| V | Sighting ports |
| W | Deflection dial |
| X | Range dial |
| Y | Recuperator ram cross-head |
| Z | Cross-head tie rod |
| a | Recoil cylinder compensating tank |
| b | Intensifier |
| c | Interceptor |
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