A note on aircraft armament in France:
"Like the British, the French had little time for HMGs, jumping straight from RCMGs to cannon. Hotchkiss did produce a belt-fed aircraft version of their 13.2mm HMG which was capable of 600 rpm, but its use is uncertain. Like the Germans, the French first experimented with large and powerful cannon, among them the 25mm Hotchkiss, a gas-operated gun weighing 70kg but initially firing at only 180 rpm from a ten-round clip. By the late 1930s the performance had improved to 300 rpm from a thirty-five-round magazine and a visiting US delegation showed some interest, but the French claimed that it was secret and refused to sell. The first French cannon to see service, however, were versions of the Oerlikon FFS already described, adapted for engine mounting and made by Hispano-Suiza as the Types 7 and 9. Early inline-engined aircraft such as the Dewoitine D.501/510 and Morane-Saulnier MS405 carried one of these together with a pair of RCMGs." (Williams, 178)
"The low rate of fire of the Oerlikon guns (around 400 rpm) was considered unsatisfactory, and as a result a much better weapon emerged (designed by a Swiss, Marc Birkigt), the famous 20mm Hispano-Suiza HS 404. This was used in the Dewoitine D.520 and MS.406, but again only one engine-mounted cannon was fitted, supplemented by four or two RCMGs respectively. It appeared that Birkigt initially tried mounting the gun rigidly as had been achieved with the low-recoiling HS 7 and 9. However, the HS 404's action resulted in a much sharper recoil blow so a recoiling mounting had to be devised, complicating the ammunition feed from the drum, which needed to remain stationary as its size and weight precluded its being rattled to and fro ten times per second." (Williams, 178)
"The French were rightly proud of the HS 404 and were intending to rely increasingly on it had they remained in the war. Some versions of the radial-engined Bloch MB-152 and the MB-155 carried two wing-mounted cannon. It was even fitted as a defensive weapon in bombers such as the Farman (Centre) NC 223 and Liore-et-Oliver LeO 451. While initial French interest was focused on a version firing a powerful 23x122 round (the HS 406), only the 20mm saw service. The gun even saw German service. Some versions of the Do 24, built on captured Dutch production lines, were equipped with the HS 404 in the dorsal cupola, and the gun was also used as an AA weapon." (Williams, 178)
"Oerlikon were not the only Swiss company producing aircraft cannon. The Swiss adopted a version of the French MS406 fighter as the D-3800 series but fitted their own engine-mounted cannon, the recoil-operated FMK38, designed around a high-velocity 20x139 cartridge which was the precursor of the current Oerlikon KAD round. Rather bizarrely, the gun was also fitted to the C-35 biplane, thus combining an ancient aircraft concept with one of the most powerful 20mm aircraft guns ever to see service." (Williams, 178-179)
Source:
Rapid Fire - The Development of Automatic Cannon, Heavy Machine Guns and their Ammunition for Armies, Navies and Air Forces, by Anthony G. Williams (2000 Airlife):
Edited by J311yfish, 21 May 2018 - 12:57 AM.
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