With the design of the 5-Inch/38 Dual Purpose Gun, the United States Navy had an outstanding piece of ordnance of medium artillery capable of surface action or anti-aircraft defense. The USN is also very fortunate in having very close connections with the Royal Navy and learned of their experiences since the start of World War Two. In August 1940 a Navy Department AA Board was organized to examine and organize the optimum ordnance and batteries for the various classes of ships in the USN.

The best available weapons, readily available at the time, were the .50 cal machine gun and 1.1-Inch cannon. By December 1940 it was clear that these weapons were still inadequate, based upon the current aerial threat. Two new weapons systems were on order but not yet available; the Oerlikon 20mm gun and the Bofors 40mm gun.

The Swiss Oerlikon 20mm cannon had been available since the early 1930s. The USN rejected the weapon in 1935 and cited a low muzzle velocity and rate of fire. It is indeed ironic that the Oerlikon company was saved from bankruptcy by an order from the Imperial Japanese Navy. During the Spanish Civil War the Oerlikon gained a reputation as an excellent piece of ordnance. The USN AA Board examined the glowing combat reports from the Royal Navy and selected the piece for installation aboard USN warships, to start in late 1941. 

Single 20mm Oerlikons
WEM350AA2215Oer.JPG (182149 bytes) WEM350AA2210Oer.JPG (124550 bytes) WEM350AA2211Oer.JPG (103733 bytes) WEM350AA2220Oer.JPG (90747 bytes)

Between December 7, 1941 and September 1944, the Oerlikon was responsible for 32% of all identifiable AA kills in the fleet. In this fret White Ensign Models provides sixty single 20mm Oerlikon guns and fittings, which is enough for almost any ship that served. If you look at the plastic pieces for the Oerlikons that come with the Trumpeter Hornet or Essex, you will see that that they are overly thick and tall. At the very least, they need the gun shields added, since they are not in the Trumpeter kits. With this WEM fret, the modeler has several options. The easiest is just to use the shields. The modeler can use the full WEM installation for complete replacement or use the gun, shield, traverse wheel, shoulder brace and sites on top of the conical plastic base of the Trumpeter box parts.

That AA kill average was steadily decreasing as the war progressed. In the second half of 1942, the percentage was 48.3% but by 1944 it was down to 25%, due to the increasing battle ranges. The Bureau of Ordnance still saw significant value in the Oerlikon, since it could be operated by crew alone, without power from the ship. To increase firepower of the system, the twin 20mm mounting was developed in 1944 and was first tested in September 1944. 

Twin 20mm Oerlikons
WEM350AA2218twinOer.JPG (87707 bytes) TwinOer9962.JPG (100361 bytes)

Most ships refitted after this date, received twin Oerlikon mounts in lieu of their single mounts. As an example, the last refit of USS Indianapolis replaced the single 20mm Oerlikons with fewer twin Oerlikon mounts. To model that cruiser in her configuration as lost, the model would have to have the twin mounts. With this fret White Ensign Models provides ten of the twin mounts. These parts include guns and shielding without the base.

For many if not most of the serving officers and men in the USN, the twin Oerlikon was still not the answer. The commander of USS O’Brien DD-725 stated, "When the 20mm opens fire, it’s time to hit the deck." Another report stated that the opening of 20mm fire was the signal to the engine room to shut down the blowers in order to keep the flash of the Kamikaze hit from being drawn into the machinery spaces.

40mm Bofors
WEM350AA2216bof&twinOer.JPG (153409 bytes) WEM350AA2214det.JPG (142818 bytes) WEM350AA2213bofer.JPG (102653 bytes)

For them, they emphatically wanted more Swedish designed, 40mm Bofors guns, which had the range and stopping power to deal with the Kamikaze threat. The Bofors design began life as a 1919 Krupp design. The AA Board worried that the 1.1-Inch gun was still too light for adequate protection and bought one Bofors for trial in August 1940. The first destroyer twin mount was with the USS Coghlan DD-606, on July 1, 1942. Thereafter, everything was being refitted with Bofors. The quad mount was a further development to provide even more fire power. All of the larger new construction, were fitted with the quad positions and as ships were refitted, the Bofors would replace the 1.1-Inch mounts and be added to other positions. By 1945 even destroyers were receiving quad Bofors. The WEM USN AA fret provides shielding, railing, and gun sites for 18 mounts. These pieces are to be added to existing plastic bases and guns in order to super detail the mount. (History from Destroyer Weapons of World War 2 by Peter Hodges and Norman Friedman.)

If you wish to add the detail to the Oerlikon and Bofors guns on the Trumpeter Hornet, Essex, Yorktown or any other USN ship model, set your sites on the White Ensign Models USN AA fret WEM PE 3555. With this super-detailed ordnance fitted to your model, you’re sure to score hits at the next IPMS show and it comes with the stopping power to stop those IPMS judges from ignoring your model.

WEM350AA2208pack.JPG (104483 bytes) WEM350AA2209fret.JPG (146012 bytes) WEM350AA2221Inst.JPG (67677 bytes)
WEM350AA2222Inst20s.JPG (49215 bytes) WEM350AA2223InstOert.JPG (51794 bytes) WEM350AA2224Inst40.JPG (95765 bytes)

WEMlogo02.jpg (7338 bytes)