Hispano Suiza type 404

The Spanish/Swiss designed Hispano Suiza was perhaps a much better weapon than the contemporary Oerlikon, with a higher rate of fire and higher muzzle velocity, but the Oerlikon had the large advantage that it was already in full production when the HS was introduced. The Dutch ordered a number of the type 404, for both the Dornier Do 24 K flying boats ( in production under license ) and on board the new TM 51-class motortorpedoboats, also under construction. Due to the invasion of Holland by the German army, it was never used in large numbers with the Dutch navy, in contrast with the American and British airforces. The Dutch cruiser Jacob van Heemskerck carried six of these guns to England, where they became a reliable part of the AA-defence, until their replacement by Oerlikons later in the war. The Dutch designated this gun the "mitrailleur v/20 mm no.1". 42 were ordered in France and 30 were delivered from the UK. 12 were lost when the freighter Tajandoen was sunk in late 1939. The turrets in which they were placed were built by "Societe d'Application des Machines Motrices (S.A.M.M. Paris)". Later, a Dutch company ( N.V. Enkes ) also started producing them under license.

TM-51 in the UK, May 24 1940

Gun specs
Gun type Hispano Suiza type 404
Origin Swiss
Purpose Close range AA
Bore 20 mm
Barrel length 1702 mm ( 67 inch )
Overall length 2502 mm ( 98.5 inch )
Classes used on TM 51-class MTB
Design 1047
Jacob van Heemskerck
Date in service with RNN 1939
Gunweight 109 lbs
Initial velocity 2880 feet/second
Rate of fire 450 - 500 rounds/minute*
Shell specs
Shell types  
Shell weight  
Range ( max )  
Ammo feed 30 round drum
Mount specs
Mount type Hispano Suiza AB-15 turret in Dornier flying boats
TM-51 class MTB's unknown
Mount armor -
Train method Hydraulic in Dornier Do 24K flying boats
TM-51 class MTB's unknown
Notes * I also found a source listing 600 rpm. I assume this was a theoretical rather than a practical speed.

Thanks to Bert Kossen for providing interesting details.


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