Spitfire out/in let question

[Snautzer]

What was the function of the the outlets? And why aren't they even in size?

( i suspect is was for getting rid of fumes from the guns but cant find the answer)

Thank you

[Graham Boak]

Although these are shown on general arrangement drawings of the A and B wings in the Spitfire Mk.V Manual, they are not included in any of the functional drawings or descriptions. A vent would seem to be the obvious purpose, though I would add the heating air to the guns as another (or alternative) requirement. They do not seem to be fitted to the PR wings.

I have also found them on earlier marks, but not (yet) on later ones. This leads to the question of how was this (undetermined) requirement met in the later designs?

And as you say, why asymmetric?

[Snautzer]

thanks

i haven't seen them on later mark spitfires. indeed with only cannon there arent any.

So thats why i thing that the .303 mg in the earlier mark needed a vent.
(Its obvious why the VA and VB had them as well. mark V being based on the airframe from a mrk I/II with a merlin 45 engine )
With less .303 on board the become scarser.

Heating air to the guns possible . air passing the vent drawing air out of the gun bays. hot air drawn from engine. I seem to remember about electric heating for the guns though

[Graham Boak]

The guns were heated by air drawn from the starboard radiator. This gave some problems with the supply to the port guns not keeping hot enough, so a pipe was added into the exhaust flow - this can be seen aft of the last exhaust.

If later aircraft had electric heating that would explain the removal of these vents.