The BL 7.5-inch gun Mark VI[3] was the 45 calibre naval gun forming the main battery of Royal Navy Hawkins-class cruisers. These ships with seven single gun mounts were significant to the cruiser limitations defined by the Washington Naval Treaty.[4]
| Ordnance BL 7.5-inch gun Mk VI | |
|---|---|
 Gun on HMS Frobisher off the south coast of England, 5 June 1944, 12 hours before D-Day | |
| Type | Naval gun Coast defence gun |
| Place of origin | United Kingdom |
| Service history | |
| In service | 1919–1945[1] |
| Used by | Royal Navy |
| Wars | World War II |
| Production history | |
| No. built | 44[2] |
| Specifications | |
| Mass | 14 tonnes (14,000 kg)[2] |
| Barrel length | 337.5 inches (8.6 m); (45 calibres)[2] |
| Shell | 200 pounds (91 kg)[2] |
| Calibre | 7.5-inch (190 mm)[2] |
| Muzzle velocity | 2,770 feet per second (844 m/s)[2] |
| Maximum firing range | 12 miles (19 km)[2] |
Description
editThese were built-up guns with two tubes, full-length wire winding, a jacket, and Welin breech block with hand-operated Asbury mechanism. The mounting was a CP Mk V a hand-operated central pivot mount with additional power training and elevation provided by a 10HP electric motor and hydraulic pump. Elevation was +30 degrees to -5 degrees and loading was possible up to +10 degrees. The total weight of the mount including its 1in open-backed shield was 45.975 tons. They used two cloth bags each containing 14 kg (31 pounds) of cordite to fire a 200-pound (91-kg) projectile up to 19 kilometres at their maximum elevation of 30 degrees. Useful life expectancy was 650 effective full charges (EFC) per barrel.[2]
Coast defence guns
editSeven guns were installed as coastal artillery in the Netherlands Antilles, five in Mozambique, three in Canada, and three in a battery at South Shields during the Second World War.[2]
Shell trajectory
edit| Range[2] | Elevation | Time of flight | Descent | Impact velocity |
|---|---|---|---|---|
| 5000 yd (4.6 km) | 2° 30′ | 7 sec | 3° 19′ | 1799 ft/s (548 m/s) |
| 10000 yd (9.1 km) | 7° 3′ | 17 sec | 12° 32′ | 1218 ft/s (371 m/s) |
| 15000 yd (14 km) | 15° 21′ | 32 sec | 27° 33′ | 1038 ft/s (316 m/s) |
| 20000 yd (18 km) | 27° 59′ | 51 sec | 44° 35′ | 1071 ft/s (326 m/s) |
See also
edit- List of naval guns
- BL 7.5-inch Mk II – V naval gun (earlier Royal Navy guns of the same calibre)
- BL 8-inch Mk VIII naval gun (used on subsequent Royal Navy heavy cruisers)
Notes and references
editBibliography
edit- Campbell, John (1985). Naval Weapons of World War Two. Naval Institute Press. ISBN 0-87021-459-4.
- Lenton, H.T. & Colledge, J.J. (1968). British and Dominion Warships of World War Two. Doubleday and Company.
- Preston, Antony (1980). Cruisers. Prentice-Hall. ISBN 0-13-194902-0.
- Whitley, M.J. (1995). Cruisers of World War Two. Brockhampton Press. ISBN 1-86019-874-0.
External links
edit
- Tony DiGiulain, Britain 7.5"/45 (19 cm) Mark VI