What are these for? (Spitfire E wing cannon blisters)

[Daniel Cox]

Hi All,

Does anyone know what these small protrusions (studs) seen on the aft end of the cannon blisters on the E winged Spitfire Mk XVI TB863 are? They feature on the cannon blisters on both wings, with two being present on the port side while three are on the starboard side. Additionally it should be noted that these studs are made from rubber and appear quite pliable when pressed with a finger.

A cropped image showing the starboard wing featuring cannon blisters with three rubber studs on the aft part of the blister.

A Cropped image from another angle showing the three rubber studs on the aft part of the starboard side wing cannon blister.

A cropped image showing the two rubber studs on the aft part of the port side wing cannon blister.

A further cropped image that shows in greater detail the two rubber studs on the aft part of the port side wing cannon blister.

I have not seen (noticed) these studs on any other Spitfire aircraft so was wondering what they are meant to be for and have they appeared on other Spitfires?

All images are Copyright ©2012 Daniel Cox.

Cheers,

Daniel.

[rs2man]

They look like ordinary rubber blind grommets . At some time , someone must have drilled holes in the blisters and these are just blanking off the holes . Why somebody drilled the holes in the first place , I cannot imagine .

[Edgar]

Judging by the line of screws, crossing the panel in line (?) with those grommets, where, on wartime aircraft, no line of screws normally existed, I'd say that something (almost certainly not to wartime requirements) has been done to the area underneath the panel.

[Daniel Cox]

Hi rs2man and Edgar,

Thanks I hadn't considered that they were rubber blind grommets, as to the panel not being quite right I concur, I could not find these grommets on any other Spitfire so I suspected it was probably unique to TB863 as seen today. According to Peter Arnold this may be part of some modification related to fitting fuel tanks into the wing for warbird use, also that the studs/grommets on the blisters are visible in restoration images when TB863 was still in primer.

On Friday I'll take the time to find out what is under those blisters and will post the results at some point over the next few days after that.

Cheers,

Daniel.