Spitfire Mk 1a guns question

[Alte Hase]

Hi all,

I'm a bit confused...in all the photos of spitfire mk I aircraft I've seen(not cannon equipped or mk Ib versions!), the four .303 guns in each wing are completely internal-no part of the gun protrudes from the wing or gun openings at all. This is supported by the fact that RAF ground crews used to stick red canvas patches flush over the gun firing openings and these would be completely flat against the leading edge of the wing.

So today I opened the Tamiya 1:48 spitfire mk Ia kit, and the two furthest outboard guns on each wing actually protrude quite a lot...about 2mm on a 1:48 kit. (this kit is definitely for a mk Ia only-no option of a cannon equipped version).

So, is this correct? did the spitfire mk Ia have any part of its .303s protruding from the wing at any of the gun positions? As I said, I've always thought the guns and barrels were entirely internal and are not in any way visible or protruding from the wing...I'm confused!

Any info or input as to whether the kit has it wrong and if I'd best remove the guns that protrude for a mk Ia version would be greatly appreciated as always!

 

[Edgar Brooks]

Early Spitfires carried Brownings which had a flash eliminator on the end; this was because it was envisaged that the aircraft could be used as nightfighters, and flash would need to be eliminated if possible. It was realised that this was unlikely (even though it was tried, in desperation, after the Battle of Britain,) and weight of fire was more important.
At the start of WW2, the early guns were replaced by a faster-firing version, with no flash eliminator; at first, the guns had "covers," which slid down the leading edge tubes, and disappeared from sight. The fabric covers did not appear until mid-1940, and were not officially used, by Supermarine, until 24-9-40.
In other words, guns protruded until the war's start; after that they were invisible, and patches were not normally seen until well into the Battle of Britain.

 

[Juha]

I have nothing to add to the main part of Edgar's answer but the use of Spitfire as a night fighter was at first somewhat successful because it was something the LW wasn't prepared for. During the first bigger LW raid against inland targets in UK on 18/19 June 40, Spits shot down 3½ He 111s, 2 by Malan, out of 5 lost, Blenheims got 1½.

Juha

 

[Alte Hase]

Thanks Edgar Brooks! That's exactly the clarification I was after!

 

[krieghund]

The book, "Spitfire the History" states that the Mk1b cannon armed version did not have any .303 guns installed which is why the big problems when the cannon jammed.

 

[Edgar Brooks]

You have to be a little wary of StH, at times; the first cannon-armed Spitfires weren't known as Ib, that designation came later. Although there were no .303" guns, the compartments remained, so they could have been refitted if the will was there; the Squadron members were just so disenchanted with the way that the aircraft swung, when a single cannon jammed, that they requested, and got, their original type of Spitfires back. Though the results, when the guns did operate properly, were spectacular, it simply didn't happen often enough. The cause was the jamming of the empty shells, after firing; several different types of feed were tried, but none worked, and it took the Vb's arrival, with a different system, to solve the problem.

 

[Airframes]

According to an armourer, and a pilot (George Unwin) on 19 Sqn at the time, the cause was the 'play' in the feed system, induced by 'g'. This would have the effect of the head of the round being misaligned with the breech, with the round tipping, causing it to bend when rammed forward, and thus jam the feed. This was eventually changed, and partly cured, by a new feed system, and the weapon itself being mounted on its side.

 

[vikingBerserker]

Great information gents!

 

[Shortround6]

This was eventually changed, and partly cured, by a new feed system, and the weapon itself being mounted on its side.

Was the weapon mounted on it's side as part of the cure or was it part of the problem?

As an engine mounted cannon (or in P-400s, early P-38s (?), and early Beaufighters the Hispano was mounted upright with the drum on top. When mounted in the Spitfire the gun was rolled 90 degrees so the gun was on it's side and most of the drum was inside the wing. An upright gun would have needed a really big fairing over the drum. When the belt feed was introduced I believe the gun was rolled 90 degrees back to upright with the rounds entering the gun through the top from the belt feed mechanism. a

As far as the outer guns protruding see:

http://www.spitfireperformance.com/20mm-303-gun-installation.jpg

Without longer barrels or the above mentions flashhiders the guns would not have protruded as the recievers were mounted behind the wing spar and unless the hole through the spar was large enough to admit the receiver the guns could not be moved forward.

 

[Edgar Brooks]

Was the weapon mounted on it's side as part of the cure or was it part of the problem?

It was the whole problem; the Hispano was designed for the shells to be gravity fed, dropped in from above, then the empties dropped out from below. Going in, and out, from the side, meant that gravity couldn't assist, and the slightest twist to the breech mounting, plus G forces from the aircraft's movement, caught and pinched the ammunition as it just sat there. There was the same sort of trouble, in WWI, with the Lewis gun, which was gravity fed, and continually jammed.
On the Vb, the empties slid straight out, and dropped through a hole beside the wheel well, so there was less for the shells to catch on.