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40mm AA gun


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Today 80 years ago.


The Dutch naval gunboat "Van Kinsbergen" meets USS cruiser "Tuscaloosa" a number of miles north of Trinidad to demonstrate her 40mm AA guns.
Tuscaloosa arrives from Guantanamo, Cuba. Van Kinsbergen comes out of Paramaribo (Dutch west indies).

This meeting comes after the witnessing of Dutch naval 40mm AA guns aboard heavy minelayer "Willem van der Zaan" in England by an American
liaison-officer a number of months before. After this the US Navy made contact with the Dutch Naval attache Meyer Ranneft in Washington.
Captain Blandy (having an important position in the Navy material department) explained that the US Navy would like to know more about the 40mm AA guns
used by the Dutch navy because they have difficulty in the development of its own 2.1 inch AA gun. A demonstration of these guns would be highly appreciated.
For this demonstration planes from Tuscaloosa are used to fly as target tugs. Aboard Van Kinsbergen are then 2 British and 2 US naval officers
to witness the demonstration. One of the latter is Blandy who flew into Trinidad especially for this occasion.

Being impressed by what he witnesses he makes contact again with Meyer Ranneft. Could he get the Technical
drawnings so that the gun could be taken into production as soon as possible in the US? Ranneft promised to see what he could do.
Ranneft succeeded in getting a complete set of micro-films containing the tech.drawnings for Blandy in a couple of weeks. A poignant detail was that a couple
of hours after Blandy received the micro-films a Swedish naval attache (or one of its representatives) made a complaint to Meyer Ranneft that the gun drawings
where of the Bofors (a Swedish) company and they had not given permission (the system making it so accurate comes from the Dutch company Hazemeyer
becoming known as a "self contained unit" with an automatic aiming, stabilisation, guidance and control unit).
Ranneft tells him to make the complaint to the Dutch government in London (Holland itself being already occupied since May 1940). If the Swedes overheard some
US talking or they did some fine intel work in this matter is not known.
After changing the drawings for American use (inches) the York, Safe & Lock company in Baltimore is given the order to produce a prototype. This was then tested at
the gunnery range of Aberdeen (to the north of Baltimore at Chesapeake Bay). This results in single, double, triple and quadriple guns being manufactured and used on
US navy vessels.
The new battleship "South Dakota" is one of those ships equipted with these AA guns. Before it was finished and set sail to the SW-Pacific Ranneft was invited
to see the ship and to see the numerous AA guns installed. The battleship later taking part at Guadalcanal. For Ranneft it must have been very interesting and
satisfying to see the numerous 40mm AA guns aboard this battleship.
After WWII America paid the Bofors and Hazemeyer companies compensation for building large numbers of these AA guns.

In Britain the gun is also taken into production by Vickers Armstrong (200 double barrelled units) but this takes more time. Apparantly because of
competition between the Department of Naval Ordnance and the Admiralty Research. These units are modified to use radar.


40mm Bofors/Hazemeyer AA gun unit on the Dutch light cruiser "Tromp". She was the first ship to be equipped with these units. 

40mm Tromp.png


USS Tuscaloosa

USS Tuscaloosa.png


Van Kinsbergen

Van Kinsbergen St Anna baai.png

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