Why on Spitfires and Hurricanes are the gunports covered....

[ILS27R]

Why on Spitfires and Hurricanes are the gunports- found on the LE covered with canvas or some other type of fabric? Seems pointless because as soon as the aeroplane opens fire the fabric will become shredded. Is the fabric just put over the gunports to prevent dirt and mud from entering the barrels when the aeroplane is on the take off roll??

Cheers,

ILS27R

[Biggles Flies Undone]

It's always been my understanding that this was to cut down the aerodynamic drag from the open gunports. I guess it also looked pretty cool to come back from a mission with the patches blown away - I wonder how many pilots squeezed off a short burst on the way home from a quiet patrol.... :D

[DOC.400]

To prevent the guns from freezing old boy!!

Damn, cabbage crates over the briney, must dash, toodle pip.

DOC

[spekesoftly]

Purely a guess, but was it also a quick and easy way of indicating to groundcrew and aircrew that the aircraft had been re-armed ?

[Who has control?]

I always thought it was to prevent condensation, but when you start to think about it, its not very effective. The canvas patch seals the gunport, but not the gun barrel. The gun bay is not sealed either, so condensation can collect on any cold surface - as it can on the inside of a half-empty fuel tank. Early Spitfires had problems with guns jamming due to frozen condensation, so hot air was ducted to the gun bays to prevent it forming.

I suspect that its a bit of all of them, aerodymanic, a warning to ground crew that the guns have/haven't been fired, to stop mud & water entering the gunports on takeoff and to reduce water ingress into the guns from rain & condensation.

[SteveR]

So basically, the answer is - because it's a very good idea.

Steve R

[Doctor Cruces]

Always understood that it was to prevent moisture entering.

The boys on TWCU used condoms from the medical centre over the muzzles to prevent same. Gun system (or so I was told) is electric and very prone to moisture related misfires. It seems the guy that used to go down ansd ask for a two gross was looked upon as some sort of sex god by the girlies in medcentre!

Doc C

[Mycroft]

Main reason is to protect barrels from debris ingress on take off. It would also serve to notify pilots/groundcrew that a/c had been armed/fueled/serviced and was ready for action. It also served to show when the guns had been fired and rearmament was required. In the Hurricane the thick wing meant that the guns could be mounted vertically and were therefore close together an it was usual to use only 1 large patch, the Spitfire's thinner wing meant that the guns had to be mounted horizontally, the ports being further apart were covered by seperate patches. The Browning .303 was quite reliable, however it was prone to stoppages due to separated cases (poor adjustment by armourer, cured by making it a disciplinary charge for the armourer). Early 20mm cannon had a severe problem with stoppages but this was cured by introducing a new feed mechanism (but of course are not covered by the question, although covers were fitted- usually not condoms but could be in emergency)

[FNG]

Somewhat irrelevant, but just had to relate that when digging in my central London garden recently I unearthed a Browning .303 shell casing. It seems to me not unlikely that it fell from a Spitfire or Hurricane in action over the city in September 1940, so now it is reverently placed on my mantelpiece.

[CyclicRick]

The Hurricanes guns were mounted vertically whereas the Spitfires were horizontal? That needs explaining I fear.

I always put a condom on my pitot tube, stops all the suicidal insects going in and reduces wear in general.

How do you get a cabby in a Spit these days, anyone know??

[Who has control?]

I think that it was the 20mm cannons in early Spits that were mounted on their sides, so that they would fit within the wing structure. The ammo feed was then vertical. The problem was that as the wing flexed, the ammo drums came into contact with the skin and caused the feed to jam.

[Mycroft]

Cyclic Rick - If you look at a Browning .303 it is oblong in cross section with the barrel near the top. Part of the reasoning for this was that the guns could be mounted 'vertically' ie narrow side uppermost allowing guns to be placed close alongside each other giving greater concentration of fire, and this was done in the Hurricane. The Spitfires wing was too thin for this and the guns had to be mounted lying on their sides, not detremental to the operation of the gun itself, butplacing the barrels further apart meant that synchronising the guns (so they all fired at the same point) was more difficult and of course led to greater dispersion of fire.

[izod tester]

I don't know the definitive answer, but it would have been unwise to rely on the fact that the gunports had patches over them to indicate that the aircraft had been re-armed. The aircraft may have had the ammunition removed for an aircraft servicing since the patches were applied. Also, the tradesman who applied the patches may well have been different from the ones reponsible for re-arming the guns.

[PPRuNe Pop]

The definitive answer is as DOC400 said right at the beginning - to prevent the firing breeches from becoming frozen, which was a severe problem until it was resolved by the use of canvas patches to cover the ports.

And as the .303 guns had only 14 seconds of continuous firing time it didn't matter much after the ports opened, and after the first few rounds were fired.

[spekesoftly]

izod

I think you may have a point about different tradesmen - hence the expression:-

"Don't ask me Chief, I'm engines" :D

[CyclicRick]

Mycroft- Aha! The way it was described it sounded as though they mounted the guns vertically as in on top of each other! NOW I understand what was meant.

On another note, does anyone else think that the reason for the, in comparison to the Germans, low number of victories in the air by our fighter pilots was because of the inferior shot load of the rifle calibre weapons used? I am aware that they certainly had an advantage over our boys in that respect (numbers) because of the Spanish Civil War involvement. I'm sure that if we had introduced cannon armament earlier it would have improved the kill/sortie ratio.
Funnily enough it looks, on paperat least, as though the Americans faired slightly better using the 0.5 inch Browning on practically all their fighters which puts alot more shot (weight) on the target and is more likely to penetrate vital systems.

[FNG]

I would say that it was less to do with ammunition and more to do with (1) the Allies rotating aircrew to non flying duties, whereas German pilots tended to fly until they copped it (2) the Germans crediting pilots with aircraft destroyed on the ground (3) the Russian front, which was initially a Turkey shoot for German pilots owing to obsolete Soviet aircraft and undertrained crews (things changed later on) and (4) sceptical Allied (esp RAF) intelligence officers demanding detailed evidence of claims, partly as a reaction to over-reporting during the Battle of Britain

[CyclicRick]

Well that told me!
I take all your points and you are most probably correct in all of them.
The only thing that got me thinking was hearing on more than one occasion of pilots actually emptying their guns completly into a German bomber before anything drastic actually happened! I Know the reputation German hardware has ( I have to admit I live and work there!) but it must have been terribly frustrating to the chaps trying to to a decent job only to see meagre results come from it. I suppose it must have trained (out of necessity) our pilots to be much better marksmen to get any kind of result in the end.

Does anyone know if there is a re-build of a Hawker Tempest or a Typhoon in progress any where? I would love to see one of those back in the air again!

[FNG]

Undoubtedly, the .303 ammunition was not as effective as the cannon shells. Another factor in 1940 would be gun harmonisation, which was set at too great a range to achieve a concentrated effect. Some pilots modified their settings for close range attacks. From 1941 onwards, cannon were more commonplace, and both gun settings and tactics improved, so these factors would have less effect on total results. B-17 crews sometimes lamented the lack of hitting power in their .50 cal machine guns, although I heard Chuck Yeager, when asked what he liked best about his Mustang, reply "the four fifties". One thing that it's easy to forget is how hard it was to hit anything with anything. Most fighter pilots on both sides rarely hit a thing. A few had the flying skills, shooting skills and nerve to get close enough to hit regularly.

[izod tester]

Tempest II MW763 is being restored somewhere in Lincolnshire and another Tempest is being restored in the US. Don't know the timeframe to completion though.