| Ammunition type | Contact fused HE fixed shell, with
or without tracer. HE/incendiary and SAP rounds were also available. The complete round (projectile plus cartridge) weighed about 0.531 lb (0.241 kg) and was up to 7.18 in (18.2 cm) long. |
| Projectile weight | 0.272 lb 0.123 kg |
| Velocity | 2740 feet/s 835 m/s |
| Maximum elevation | 90 degrees |
| Range | 4800 yards 4390 meters |
| Altitude | 10,000 feet 3050 meters |
| Rate of fire | 480 rounds per minute |
The Swiss
Oerlikon is usually regarded as a successful design, and it was
certainly a
vast improvement over heavy
machine guns firing solid shot. It won high praise for its
performance at the Battle of
the Eastern Solomons, where it accounted for at least half of all
the Val dive bombers that attacked the American carriers. It was calculated
that by September 1944 the Oerlikon had accounted for 32 percent of all
identifiable antiaircraft kills by the Pacific Fleet. It was usually
shipped
in single free-swinging mounts with splinter shields. Fire control
was initially based on simple optical sights,
but the Mark 14 gyroscopic computing gunsight was developed early in
the war. As the war
progressed, ships undergoing refit tended to ship additional guns
wherever there was enough space on deck to bolt one down, limited only
by magazine
capacity and top weight. (The single free-swinging mount, gun, and
shield weighed about 1700 lbs [770 kg]).
However, the single 20mm
proved too light a weapon to fend off the kamikazes. One destroyer commander reported that "when the
20 mm. opens fire, it's time to hit the deck", while another report
noted that "20-mm. fire was a signal to the engine room to shut down
the blowers to keep the flash of the explosion from the suicide hit being drawn into the machinery spaces" (Friedman
2004). Single mounts were beginning to be replaced by dual or even
quadruple mounts by the
end of the war. Most of the dual mounts were also free swinging, but a
few dual mounts and the quadruple mounts were powered and were directed
using a joystick and the Mark 51 director. The latter was a Mark 14
mounted on a "dummy gun".
The sustained rate of fire of most models was much reduced by the need to pause and reload the 60-round magazine. An experimental quad mount using belted ammunition would have had a sustained rate of fire of 150 rounds per minute, but was superseded by by twin 40mm Bofors mounts.
References
The Pacific War
Online
Encyclopedia © 2007, 2009-2010 by Kent G. Budge. Index
