Battle of Britain fighters

[Tony Williams]

I have posted an evaluation of the armament of the principal Battle of Britain fighters at: http://www.quarry.nildram.co.uk/BoB.htm

Tony Williams: Military gun and ammunition website and Discussion forum

[Xjazz]

Thanks!

My regular h2h ride is Hurricane Mk I, so its nice to read some RL info.

[Engine]

Nifty stuff.

[Kweassa]

Thank you for the invaluable info Mr.Williams.

 I don't know, but it feels like the conclusions are a little bit consciously 'balanced out' , but it could be just me.

 The postscript about the Hispano-Suizas, I think, itself indicates a decisive 'judgement' that raises the hand of the cannon-armed scheme as the victor - clearly, the case of the USAAF/USN is more of an anomaly when seen in the context of armament schemes of the entire war.

 I've personally always thought that the need for having to arm 8~12 guns on a single plane, especially on the wings, is not as much an 'awesome display of firepower' as 'inefficiency'. A lot of good arguments have been made in the debate between the efficiency of cannons vs machine guns.. but most of the reasoning is about combat effectiveness, which I tend to agree both schemes were about equal.

 But what about it in regards to costs and maintenance issues? Reload times? Ammo configuration? Ammo stores? I don't think I've ever seen a comparison in that aspect (- probably because of the limited sources of reference I can get my hands on in Asia  )

[GScholz]

Our poor MG-FF or even 151/20 is nowhere near as powerful as the Hispano. I wonder if HTC will address the apparent undermodeling of HE blast damage in AH aircraft guns. I believe they've said they'd look into it.

The 20mm cannon did not entirely rely on the M-Geschoss. There was still a requirement for some tracer rounds, so lighter 117 g projectiles were developed (by fitting the 134 g HE-T with a light-alloy instead of brass fuze), loaded down to around 585 m/s (1,920 fps) to match the recoil characteristics of the M-Geschoss. The effectiveness of the M-Geschoss was somewhat reduced by the fast-acting fuze, which detonated instantly rather than inside the target's structure, although this was probably more of a problem against bombers than fighters. The British rated the M-Geschoss as about equal with the 20mm Hispano round, which contained much less HE but had a heavier shell fired at a higher velocity and could penetrate more deeply. Delayed-action fuzes for the German shells were introduced in 1941. AP shells were also developed later and were not available during the Battle of Britain.

[Batz]

It would seem that damage in AH is related more towards impact velocity. The problem with the MG FF was that its low muzzle velocity (longer flight time, trajectory drop) reduced hit probrability. Not that its damage was greatly reduced.

 The Minengeschoß round needed enough velocity to penetrate the skin of an aircraft. Granted the higher its velocity at impact the deeper it would penetrate before exploding. However, the Minengeschoß rounds were designed to destroy the structural integrity of stressed skinned all metal aircraft. They were effective in doing this. They had a harder time with the cloth skinned aircraft.

Maybe Tony can answer this for us.

What your is opinion of possible damage of the MG FF/M (I am not sure what rounds HT models, Minengeschoß?; hybrids?) at 250yrds? and 500?

There's a huge difference in the AH MG FF @ 250 and 500.

[Tony Williams]

Well, the whole question of fighter gun effectiveness was of course examined in the article I wrote with Emmanuel Gustin at: http://www.quarry.nildram.co.uk/WW2guneffect.htm

The problem is in separating the questions of destructiveness and hit probability. The destructiveness of cannon ammo didn't fall off much with distance, as it significantly depended on the HE blast which remained constant. However, the hit probability was another matter, especially with a ballistically poor weapon like the MG-FF/M.

The extent to which hit probability reduced with distance would of course depend on the nature of the target; a big bomber flying straight and level could be hit reliably from some distance away, a fighter was much harder and a manoeuvring fighter harder still.

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[Dowding]

Tony - I've been following an argument on another board regarding contact detonation of shells versus delayed action fuzes.

"Delayed-action fuzes for the German shells were introduced in 1941. AP shells were also developed later and were not available during the Battle of Britain."

I was just wondering what supports these statements - I'm assuming you have access to production records in German munitions factories or records of LW inventories or perhaps the actual dates from the weapons labs?

[Tony Williams]

The delayed action fuzes comment comes from various sources, including RAF tests of the German ammo (original documents in the PRO). The AP one is from ammo collectors who specialise in Luftwaffe ammo - no 20mm AP for the MG-FF or MG 151/20 dated earlier than 1941 has been found, and there is no documentary evidence to suggest it was available.

Tony Williams: Military gun and ammunition website and discussion
forum

[Dowding]

That's interesting. Thanks.

[Batz]

The 20x80RB M-Geschoss and the 20x110 (Hispano) HE were rated as about equal; the greater blast effect of the M-Geschoss was countered by the greater penetration and kinetic damage inflicted by the Hispano. They do indeed emerge with similar scores

[Tony Williams]

I have amended the 'Battle of Britain Armament' article to include additional information about the loading of the .303 guns and the selection of the 20mm Hispano.

See: http://www.quarry.nildram.co.uk/BoB.htm

Tony Williams: Military gun and ammunition website and Discussion forum