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Alleycat 1/32 Spitfire PR XI


thierry laurent

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Hi guys,

 

While checking the contents of the conversion, I was a little bit puzzled by the two single cockpit components. Of course they are very visible elements but the out of my memory the PR XI had alas many more other features. So again I allocated my train journey time to an interesting task: to check all the changes.

 

I'm currently allocating the few hours I have at home to a project to help someone but when I will get some additional time I will try to take some pictures of the modifications I made last year.

 

Just to inform you, that mark had MANY other cockpit changes and some were VERY visible if you compare the pictures with the ones of a fighter.

 

To give some hints:

 

- the upper starboard side is completely different with no spare gunsight bulbs and no more fuel pump, morse key or gyro gunsight component. From the front to the rear, the PR cockpit had a box to stow a ration, a latch for maps, a lever to open the belly camera shutters and two supports for a cylinder-shaped incendiary bomb (I guess this was intended to destroy the plane in case of crash). If you open the cockpit door such features are VERY visible. By the way, the oxygen tube should be added as well.

 

- the port side did not change a lot. Alleycat give the large camera selector box but not the large support with two thermometers bezels that was added between the door opening and the front instrument panel. This is a very visible feature. Moreover, a relief tube with a funnel was going out of frame 10 on late production planes. However, I never found a picture of that change and this was probably not very visible.

 

- the instrument panel had additional features as well. A small fuel pressure warning lamp was added on the right side of the type 35 camera control box given by Alleycat. This is a very small and not obvious change. However, the left lower side of the panel got other very obvious changes that should normally be added: two large bezel boxes (a clock and a ammeter) were added on the lower port side, right under the IP. A slow running cut-out ring-shaped control was also added between the aforementioned additional bezels and the compass.

 

- the rear seat armor shall be removed and the seat had the flare holder but this was made out of a single peforated metal sheet. The flare pistol was seemingly clipped to the seat starboard side. I guess this was close to the very front end of the seat as the large seat heigth adjustment lever does not really give other options but I never found a picture. Most wartime planes had no head cushion but some got one (check your references).

 

- the rear cockpit also changed noticeably. The oxygen bottles had to move because an additional fuel tank was added between frames 11 & 12. Three smaller bottles were stored horizontally over the tank (from the front to the rear of the plane). If that area is not the most visible one of the cockpit, the color of the bottles really reveal the changes. This is an annoying omission as this ask for scratching all the components... I would not go mad detailing the black rubber covered tank but at least creating the main shapes is recommended.

 

- I do not know if this would be really visible on a kit but the radio was relocated close to frame 12 to give room for the cameras. Personally, as this was just a black box in a dark area, I would not really worry about that.

 

- Finally, the boots straps should not be added on the rudder pedals.

 

Note an external change should also be done: the wartime planes had no torsion links on the landing gear legs.

 

This shows that the amount of internal changes unfortunately goes far further than adding two resin boxes...! Of course, solving that comprehensively would ask for giving a full resin cockpit and I understand Alleycat did not want to go that route. However, some additional resin components such as the additional bezel boxes, the most visible items of the starboard side, the fuel tank and the modified oxygen bottles could have been included.

I had to cross check many sources to do that list. Again, this shows that the "well-known" Spifire still deserves better documentation... The best book stays the Ventura part II about reco Spits but it does not cover everything...

 

I hope this helps.

 

BR

 

Thierry

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A point I forgot: the fuselage fuel tank is a mystery to me!

 

The Wright Patterson museum plane has clearly a tank under the oxygen bottles...BUT...

 

The fuel tank system TM view of the PRXI I have does not mention such a tank. The Mk IX had a ferry tank but it was far larger and the one of the PR VII is not similar either as it heigth was taller!

 

So, I am puzzled! To me, the tank location was logical as the plane even got wet wings to lengthen her range and the relocation of the oxygen bottles is a clue that it was necessary to make room for something! Moreover, it was located close the center of gravity.

 

As the PRXI was built in some batches I am nonetheless wondering if all of them got a fuselage tank and how it looked like. Fortunately, even without the armor plate the seat plus the oxygen bottles will hide most of the features. I will probably just make a kind of box that corresponds more or less with the dimensions of the available area!

 

Thierry

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AFAIK the reaf fuselage tank was not standard on the PR XI, but I'll have a dig in my "bibles", Venturas Merlin PR Spitfires and Merlin PR Spitfires in Detail. 

 

 The best book stays the Ventura part II about reco Spits but it does not cover everything...

Yes indeed.

 

Thierry, thanks for this: all very useful and timely as I'm considering breaking out the Alley Cat set and starting one myself.

Edited by MikeC
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Sorry for the delay, got distracted.  Info and direct quotes from Merlin PR Spitfires, Wojtek Matuisiak, Ventura, 2007.  Bear with the bit about the D - it's relevant (I think).

 

The PR D was the first true production PR variant - the A, B, C etc were all conversions of standard fighters.  The initial Ds had a "wet" wing with a 57 gal tank in each wing, and the 29 gal rear fuselage tank.  (Also an extra oil tank in the port wing inner gun bay space.)  Fully loaded with fuel it was dificult to handle. "The aircraft was barely controllable during the first 30-60 minutes of flight until the rear fuselage tank emptied."

 

The D was considered acceptable, and put into series productiomn.  Standard production Ds, or PR IVs as they came to be designated about this time, had larger wing tanks of 66.5 gal each, and dispensed with the rear fuselage tank.  Total fuel tankage with the forward fuselage tanks was 218 gal in all, giving a range of about 1800 nm, which was about 100 nm further than the initial Ds.

 

Why is all that relevant?  The D essentially set the standard for subsequent PR Spitfires.  "From this variant on, the arrangement of all principal components was set: cameras in the rear fuselage and integral wing tanks.  From then on development of PR variants followed the path of fighter versions; ie ever more perful engines were fitted to improve performance, expecially service ceiling and top speed, in order to keep ahead of the latest German fighters."

 

There is no mention of rear fuselage tanks in the PR X/PR XI.  My own conclusion is that the Spitfire XI did not ever have any rear fuselage tank; I'll be happy to say I'm wrong if someone can produce definitive info or better still a photo.

 

Don't you just miss Edgar?

Edited by MikeC
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Thanks Mike,

 

Yes Indeed! He would probably give us the final word without hesitation!

 

What you found confirm the PRXI tech manual view I found BUT in that case there are still two aspects I do not understand:

 

1. Why is there a fuselage tank in the Wright Patterson PRXI?

 

2. Why did the PRXI use three small oxygen bottles located horizontally behind the seat to make room in the fuselage as the classical configuration was one small bottle located horizontally and two large ones set vertically? This puzzles me as all fighters produced at the same time got the vertical bottles! So why building the PR planes with such a non-standard configuration with less oxygen if there was a final decision to only use wing tanks...?

 

I am wondering if the classical configuration was not wing fuel tanks BUT with a provision kept to use a small fuselage tank in case of need. This is the only conclusion that looks logical to me and would explain why the US preserved plane has such a tank!

 

Thierry

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All valid questions Thierry.  However, the USAF Museum a/c is not all it seems.  Apparently it started life as PA908, served on 681 Sqn in India, and then as a ground instructional airframe with the Royal Indian Air Force before going to the US and to the museum.  http://www.airhistory.org.uk/spitfire/p084.html  The real MB950 was written off in 1945 http://www.airhistory.org.uk/spitfire/p061.html .

 

So whilst I don't doubt the diligence of the restorers, I'd be interested to know the reason for the apparent fuel tank.  Things done by Indian trainee fitters perhaps?  I believe the PR XI could carry a standard Spitfire slipper tank, so I would imagine there would be no point in having a rear fuselage tank that would undoubtedly be very difficult to fit. 

 

As for the oxygen bottles, no idea.  It certainly had this mod - perhaps a hangover from the PR IV design?  When the decision was taken to delete the rear fuel tank, the oxygen bottles were probably left as they were, no point changing?

 

I'll keep digging and I hope between us we can get to the bottom of it.   :)  

Edited by MikeC
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Well, hopefully!

 

Moving the internal tank was by no means easy as this required the prior complete removal of the seat...! However, this still offered a noticeable advantage for a long-range PR plane: no drag. So, this does not seem illogical to me.

 

As you, I had doubts regarding the restored airframe but this does not explain the effort to set-up such a non-standard oxygen configuration. Weird...

 

Thierry

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The PR.XI preserved at Gardermoen in Norway has three oxygen bottles behind the seat.  Me theory for this is that the PR.XI had a longer endurance than the fighters (evidenced by the deeper lower cowling for the enlarged oil tank), and as the pilot would be expected to stay high and fast, there was a need for more on board oxygen than for the standard fighter.  The two vertical tanks behind the seat on the port side were for air to cocke the guns (for the fighters) and presumably also the brakes since this PR.XI still have them installed, but were not oxygen designed for breathing.  There is no fueltank in the fuselage behind the pilot of that particular aircraft, but it could have been removed at some point in it's life?

 

Looking at my pics now, and I may be mistaken about that.  The tank might be between the oxygen bottles and the camera installations?  The cockpit is not complete - the undercarriage selector is obviously missing for a start...  All my own photos.

 

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kZB0mn2.jpg

 

Jens

Edited by jenshb
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OK ! At least this explains the bottles differences. So, I have to recreate the large ones I cut to make the small ones...

 

Thanks very much for your pictures. They show some support and connexion details of the bottles that I could not see so clearly.

 

If the vertical bottles were still used as a standard configuration, there is no room for a tank. So, even if this stays an oddity regarding the US preserved plane, I think that leaving an empty space under the bottles stays the most cautious and logical choice!

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http://www.spitfireperformance.com/spitfire9-fuelsystem-lr.jpg

 

http://c8.alamy.com/comp/KPHBPT/fuel-tank-from-a-spitfire-of-the-battle-of-britain-memorial-flight-KPHBPT.jpg

 

Just pull one out of the Mk XVI if you want one.

 

Hope this may help

Edited by Vandy 1 VX 4
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