Supermarine Spitfire gas vents

[Wirbelwind]

Hi guys,

It's my understanding that the Spitfires had two circular gas vents near the gas filler cap (as seen here circled in red). However when I look at the Spitfire Mk1a N3200 (detailed picture here), I don't see any gas vents at all. I know that this particular Spitfire is a complete rebuild as the original wreck from Calais beach was damaged beyond the point of restoration, but I do know that they followed the specs/blueprints down to a T, even going as far as using original construction methods whenever possible.

Were the gas vents omitted during the build or did the original N3200 Mk1a not have them either? I'm pretty sure I've seen at least one other Mk1a that did have the gas vents clearly visible.

Thanks,
Max

 

[Airframes]

Looks like the vents are there, aft of the filler cap.

 

[Wirbelwind]

Looks like the vents are there, aft of the filler cap.

Do you see them in this picture of N3200?



I don't see them at all. I know where they're supposed to be, but all I see is a smooth surface there.

 

[Airframes]

Yes. I'm on a campsite at the moment, 6 miles from where that Spit is based, using a lap top. With limited enlargement, I could see both vents, aft of the fuel filler.
I can check my files on my home computer when I get home, but I'm fairly certain the vents are there.

 

[Wurger]

Actually there is one hole on the port side. It seems that the kite had it just in the way... the enlarged shots show it quite clearly. There is one black dot only.

 

[Wirbelwind]

Interesting. Thanks for those close-up shots of the cowling, Wurger.

Can anyone shed some light onto why this particular Mk1a doesn't have the "standard" two gas vents aft of the filler cap?

 

[Airframes]

Being away from home, I can't check my references, but at a guess, it may be the configuration for a single fuel tank, as opposed to the upper and lower tanks.

 

[Wurger]

I agree. When the two tanks were combined there was the one vent only which was a 1/2" hole inside the 1" cutout in the cover on the port side.

 

[Wirbelwind]

Was the combined tank with the single vent a later modification on the Mk1?

 

[Wurger]

It was later modification for late Spitfires as memo serves. So the Mk.I should have the pair of holes there. At least the layout can be found in many other shots of the Spit variant. Unfortunately none of the existed images of crashed N3200 allows to see the number of cutouts and get it for sure. Because the flying plane was restored almost from scratch it is possible it could have had the later fuel tank installed.

 

[waroff]

On the port side, it is a bonding socket to grounded the airplane during refuelling.
The fuel vent outlet is forward the radiator fairing

 

[Wirbelwind]

It was later modification for late Spitfires as memo serves. So the Mk.I should have the pair of holes there. At least the layout can be found in many other shots of the Spit variant. Unfortunately none of the existed images of crashed N3200 allows to see the number of cutouts and get it for sure. Because the flying plane was restored almost from scratch it is possible it could have had the later fuel tank installed.

Are you sure that the dual vents were only present on the early Mk.I spitfires? I see that MH434 has two vents in the photo below.

Aviation Photo #5513985: Supermarine 361 Spitfire LF9B - Untitled

Also, how many vents would the Mk.IIa and Mk.IIb have had?

 

[Wurger]

I'm afraid you got me wrong. The Mk.I , as the earlier plane, had the two fuel tanks there rather. So there were the two cutouts for the "vents". Later Spitfire models had the two cutouts too. But in fact the hole in the cutout was in the port one only. The starboard one either got there a screw or there was nothing. So please don't confuse the number of cutout with the holes (vents) there. Actually waroff migh be right but I have heard two different opinions on the "vents". Here a couple of shots found via the net.

the pic source: the Internet.

 

[Wurger]

And here two shots more. The top is for Mk.IX just of the MH434 and the bottom one of the Mk.IX NH183.

the pic source: http://www.rcuniverse.com/forum/rc-...4-carf-spitfire-assembly-scale-detailing.html

 

[waroff]

Spit Mk I

Filler position, Bonding socket position and ????? position ?
above, seen on Mareng type tank(steel)
below, tank build in 20G Alclad

 

[Wurger]

So all should be clear now.

 

[Wirbelwind]

Someone correct me if I'm wrong, but so far I've learnt that:

1. All Spitfires (at least Mk.I to Mk.IX) had two cutouts aft of the filler cap
2. Early Mk.I Spitfires with two separate fuel tanks had two cutouts aft of the filler cap, and two vents (one in each cutout)
3. Later Mk.I Spitfires with combined fuel tanks also had two cutouts aft of the filler cap, but only a single vent in one of the two cutouts

Does this mean that N3200 has two cutouts even if there's only one vent hole? I'm having difficulty seeing both cutouts in the picture of the rebuilt N3200 in my original post... or perhaps it's just difficult to see.

 

[waroff]

1. All Spitfires (at least Mk.I to Mk.IX) had two cutouts aft of the filler cap.
2. Early Mk.I Spitfires with two separate fuel tanks had two cutouts aft of the filler cap, and two vents (one in each cutout) read the description of vent pipes in the post above, the outlets are not on the top surface of upper tank. I coloured in red the vent pipes.
3. Later Mk.I Spitfires with combined fuel tanks also had two cutouts aft of the filler cap, but only a single ventNo, it's not vent hole but a bonding socket

the only technical drawing(Mk I & II) of cowling fuel tank show two holes after the filler hole, so it could be used with any type tank

 

[Wirbelwind]

1. All Spitfires (at least Mk.I to Mk.IX) had two cutouts aft of the filler cap.
2. Early Mk.I Spitfires with two separate fuel tanks had two cutouts aft of the filler cap, and two vents (one in each cutout) read the description of vent pipes in the post above, the outlets are not on the top surface of upper tank. I coloured in red the vent pipes.
3. Later Mk.I Spitfires with combined fuel tanks also had two cutouts aft of the filler cap, but only a single ventNo, it's not vent hole but a bonding socket

the only technical drawing(Mk I & II) of cowling fuel tank show two holes after the filler hole, so it could be used with any type tank

Ok, that makes things a little more clearer.

I am right about all Spitfires from Mk.I to Mk.IX having two cutouts aft of the filler cap regardless of how many vents there are, yes? If that's true, then I still can't figure out why the rebuilt N3200 appears to only have a single cutout in its cowling...

 

[Wurger]

To annswer the first part of your question ... yes two cutouts aft of the filler cap regardless of how many vents there are.

To replay the second question ... as you may notice in the pics above there are two cutouts but there is one hole in the port one only. If the port cutout with the hole is the bonding socket but not the vent hole and there is nothing in the starboard one it is quite obvious that the starboard cutout is not needed anymore. And that's the reason it was omitted while making the new cover of the fuel tank compartment. One more hole to drill , more work to done and nothing to get. Just my opinion.