Spitfire Stencilling I have not seen before

[JohnT]

I was watching the BBC News on line and an interview with Wing Commander Paul Farnes here

 

https://www.bbc.co.uk/news/uk-44775939

 

At 1.53 and following there is a still photo of him in his spitfire in the cockpit.  The hood is pushed back and under the canopy just aft of the fixed closed rear portion there appears to be writing that I don't recall seeing before on a Spitfire.  It is partially obscured but could read :-

 

"This..

Not to...

........."

 

I cant make out the other words.

 

Any thoughts chaps?

 

John

[Pete in Lincs]

Looks like, This tank not to be filled.....

 

Missing words? could be, Completely or to the top or beyond half?

Probably something to do with the CG on that aircraft?

I can't remember seeing it before either, but an expert will be along presently.

[JackG]

No idea here either, but it looks more hand written or chalked in place rather than an actual stencil?

[Alex Gordon]

Is this the image?

 

 

I'm looking at the odd bit on the top of the rear canopy section and thinking that it's a new one on me.

 

Edited to add; Internally armoured windscreen,round rear view mirror,fully blown sliding canopy portion,cut here marks around sliding canopy portion,light coloured squadron code letter.Could this be a post war Mk21?

Edited July 10, 2018 by Alex Gordon

[Corsairfoxfouruncle]

Here it is blown up further. 

looks like @Pete in Lincs is correct.

[JohnT]

27 minutes ago, Alex Gordon said:

I'm looking at the odd bit on the top of the rear canopy section and thinking that it's a new one on me.

 

Edited to add; Internally armoured windscreen,round rear view mirror,fully blown sliding canopy portion,cut here marks around sliding canopy portion,light coloured squadron code letter.Could this be a post war Mk21?

Nicely observed Alex.  Sometimes the more you look at photos the more questions that crop up.

 

I think Peter hit the nail on the head and I do wonder if the writing at the cockpit is a "one off" direction for that particular aircraft for some reason.  

 

Now I am wondering about the oddity on the top of the rear canopy section too.  It reminds me of some flush aerial panels you see on jets but thats not it surely

[gingerbob]

If the squadron code is 'FJ', I make this to be 164 Squadron.  According to Wiki, they had Spit IXs from June '45, to XVI July '46, but changed to 63 Squadron at end August.

 

Excellent spotting, and that is definitely an aft fuel installation.  This was in the works for some time, and use was forbidden unless specifically authorized after the war (whether it was ever used DURING the war is another question).  I think it's the first time I've seen a high-back in squadron service so fitted.

 

bob

[fewr9fkr9595]

Could it be a filler of some sort? As in a one off tank on this particular plane that the chalk refers to?

There seems to be a ‘neck’ coming down from it? 

[JohnT]

This is when we miss Edgar so very much

[Graham Boak]

Mk.XVIs and some Mk.IXs were fitted with the aft fuel tank, but as long as it was full aircraft could not carry out combat manoeuvres safely.  This made it unusable by Fighter Command in Eastern England which already operated with external tanks.  What was needed was the new larger tail that was never fitted to Merlin Spitfires.

 

However the fighter bomber units operating on the Continent could not carry external tanks because they were using that position to carry bombs, so they found this extra fuel capacity very useful.   The restriction was that the aft tanks should be emptied first, before reaching enemy territory. The same restriction applied to P-51 s and P-47s of the 8th AAF.

 

My understanding is that deliveries of the Mk.XVI was delayed until these aft tanks were cleared, resulting in a large stock of these fighters building up until December 1944.

 

[Pete in Lincs]

See, an expert in a fast taxi. 

Nice bit of information, Graham.

And thanks.

[gingerbob]

Sorry Graham, but the XVI was being delivered well before the aft fuel installation was cleared.  There are even low-backs that do not have the filler spout, which I interpret to mean no aft tank fitted.  I have a fair amount of data about the intentions, but my trail goes a bit cold when it comes to actual results.  As near as I can figure, the green light wasn't given until at least March or April '45.

[Graham Boak]

I recall Edgar talking about a build-up of Mk.XVIs awaiting a clearance, and that this was linked to the aft tanks saga.  Or was this some other mod?  If the aircraft wasn't built with the aft tanks then there's be no reason to delay their service use, as you make clear.

 

The difference in use between the two organisations remain.  I think that FC 's objections have an air of "not invented here" about them, and ways around the  main (genuine) problem could have been found, but without full information it's impossible to be certain.

 

There were two tanks - a low one that could be fitted to all Spitfires, and a high one that could only be fitted to the original fuselage.  Quill implies that the stability limit was reached at some intermediate fuel state, but I've not seen it specified what this was.  It would be easy to suppose that this could equate to the lower tank only, but I think that's unsafe.

 

That full inscription might be helpful in that respect.  

 

Regards 164  Sq. Postwar it was suggested that the FJ codes were dropped on favour of UB, but this photo shows that FJ was retained for some time.

[JohnT]

I never cease to be amazed and awed by the extent of members knowledge on here.

[Gwart]

On page 115 of the Merlin SAM datafile is a more specific diagram for the rear fuselage tank in standard back IX +.

 

 

[72modeler]

1 hour ago, Gwart said:

On page 115 of the Merlin SAM datafile is a more specific diagram for the rear fuselage tank in standard back IX +. 

 

Graham and gingerbob,

 

Certainly no expert on the Spitfire, but after reading the discussion and looking at the photo and diagram, could the stenciling have something to do with not filling the fuselage tank completely? Perhaps only filling the bottom 33 gallon fuel tank to keep the cg within safe limits? Only filling the lower tank would preclude fuel sloshing around, as what happened when the 85 gallon fuselage tank in P-51's was only partially filled to keep the  cg at a safe limit.  I learned something new here, as I had thought only the bubble canopy XVI's and subsequent had a fuselage fuel tank fitted.

Mike

[Gwart]

It looks like 'This tank is not to be filled'.Probably due to stability problems as you mention @ Mike/72 .

[Graham Boak]

Going back to the diagram in post 15.  The Modification numbers suggest that the lower aft tank preceded the larger forward tank, but I had understood that this was already standard on the Mk.VIII.    Is this wrong?  Or was this Mod. 1377 specific to the Mk.IX/XVI?  I have also seen that this tank was unpopular with ground crews for the difficulty in removing and replacing it, but that may not be Mark specific.

 

I've wondered how the larger forward tank and inner wing tanks on the Mk.VIII affected the instability of the rear tanks.  The extra weight forward would have compensated to some extent.  Without knowing the acceptable level of fuel in the rear tanks it's not possible to judge, and what was acceptable to Quill may not have been acceptable to the RAF for less talented pilots.  Use of these forward tanks would have provided the RAF with a somewhat more usable fighter at a longer range but heavier in combat.  However I do not recall any mention of differing internal fuel states affecting the combat value of earlier Spitfires.

 

The Mk.XIV had the inner wing tanks, and a heavier engine/prop combination.  Perhaps the aft tanks would have been more acceptable  on this variant?  At least in wartime - the Mk.18 suffered the same postwar prohibitions on their use. That doesn't mean that the same restrictions would have applied to the type n wartime - witness the instability of the P-51 with similar aft tanks.