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Another early Spitfire question: the voltage regulator cabling


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Hi,

 

The early Spitfire had a dome shaped voltage regulator that from the end of the Mk I/start of Mk. II production was changed to the common two cylinders-shaped system. Various pictures show that the cabling of the later type clearly went down on the port side of the bulkhead. However, I could not find a clear picture for the early one. There is just one in the Aerodetail dedicated to early Merlin Spitfires and it seems to indicate the cabling went to the other side and entered into a hole in the top of the bulkhead. However, this is probably only part of the cabling while most of the cables would indeed go down on the port side. The 1/24 Airfix kit shown in the old PSL book seems to indicate that the cabling was taking the same port route than on the later types. This is the logical approach but as many changes occured at the end of the Mark I production, I'm not absolutely sure and as this area is right under the rear canopy, behind the head armor plate, it is very visible. So, I would like putting the cabling correctly.

 

For those who do not know what this part is, here's a picture of the one I made for my kit: i1X8LQi.jpg

 

I still need to add screw heads and rivets. BTW, I had just ended making the part that I realized I had the same part in my spare box (coming from an Eduard set)! However, as there are slight dimensions differences between the Aires set I'm using as a base for my cockpit and the Eduard one, the resin part looks a little bit too small. At least, I didn't do that for nothing and I will use the resin part in another early mark kit.

 

If anyone has any information about that cabling, I would be glad to get it!

 

Thanks in advance

 

Thierry

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Well...

 

It looks I'm particularly gifted to question myself about obscure topics or items that should not be taken for granted too quickly...! ;-) Edgar, where are you...?

 

For some weird reasons, it is very difficult to find pictures of that device in situ whereas there are multiple airframes that were preserved and restored with that configuration (N3200, X4650, X4590, R6915 or P9444).

 

There's one good picture of Mk.Ia X4650 on Wikipedia (https://commons.wikimedia.org/wiki/File:Supermarine_Spitfire_I_‘X4650_-_KL-A’_(G-CGUK)_(40121560291).jpg#filelinks) but again that area is not very visible.

 

By the way, I also observed that system changed noticeably during the Spitfire long life. Initial Mk.Is had none. Than, the dome-shaped cylinder system appeared during the Mk.I run up to the beginning of Mk.II batches. It was then replaced by the more common double cylinder-shaped system. And finally it disappeared during production of the Mk.IX and on subsequent types.

 

The quest goes on...

 

 

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Thanks.

 

It is quite weird nobody seems to have worried about that before as that area is quite visible because of the location under the canopy. 

 

The Mk.Is are not that common on LSP but three kits were released for that mark: the Airfix 1/24th kit, the Revell first 1/32 Spitfire and one release of the Hasegawa kit (actually a late Mk.IIa/Va).

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Hi guys,

 

I think you would be interested in knowing I probably found the answer! Cox drawings are known to be quite accurate and they clearly show the cabling going down on the port side of the bulkhead. So, again this went against what I deciphered on the Aerodetail picture but the bulkhead port side was not visible on that one. So, I was still puzzled by such discrepancies.

 

And then, I finally found pictures of the plane preserved in Chicago. The interesting part is the fact that plane was not a "restored" airframe. The pictures show that part of the cabling is going in down on the port side whereas the other is going to a hole in the bulkhead on the starboard side. Have a look at the arrows. This explains what I saw in the Aerodetail book.

 

cR1k94B.jpg

 

Conclusion: the cabling is not the same than on later planes but not fully different either! However, no drawing, nor current kit or aftermarket set is correct regarding that detail.

 

Hope this helps!

 

Thierry

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  • 5 months later...
On 3/4/2020 at 12:07 PM, thierry laurent said:

Well...

 

It looks I'm particularly gifted to question myself about obscure topics or items that should not be taken for granted too quickly...! ;-) Edgar, where are you...?

 

For some weird reasons, it is very difficult to find pictures of that device in situ whereas there are multiple airframes that were preserved and restored with that configuration (N3200, X4650, X4590, R6915 or P9444).

 

There's one good picture of Mk.Ia X4650 on Wikipedia (https://commons.wikimedia.org/wiki/File:Supermarine_Spitfire_I_‘X4650_-_KL-A’_(G-CGUK)_(40121560291).jpg#filelinks) but again that area is not very visible.

 

By the way, I also observed that system changed noticeably during the Spitfire long life. Initial Mk.Is had none. Than, the dome-shaped cylinder system appeared during the Mk.I run up to the beginning of Mk.II batches. It was then replaced by the more common double cylinder-shaped system. And finally it disappeared during production of the Mk.IX and on subsequent types.

 

The quest goes on...

 

 

The Voltage regulator fitted to the back of frame 11 on a MkI, Mk II or MkV Spitfire is a 12 volt regulator that has a simple on off toggle swith to operate next to the volt meter and ammeter on the instrument panel.

 

The Voltage regulator with twin barrels fitted to some Spitfire Vc's and MkIX's is a 24volt regulator fitted in comnjunction with a major rediesign of the whole aircrafts' electrical system in late 1942. The dials and switch remain in the same position on the instrument panel.

 

All spitfires built with a Merlin II engine - ie K9787 up to K9980 had a different wiring, no regulator and a twist switch with three positions - OFF, HALF, FULL so once 12.4 volts had been reached in flight the pilot would switch to "HALF CHHARGE" and leave it there unless the voltmeter showed less than 11.5 v. In other words the pilot was the regulator. You will not find this in any published book including Shacklady.  There is an issue as to when the wiring changed, some people I know are convinced it coincided with the introduction of the Merlin III, personally I am not convinced of that since no L series Spitfire I know has a regulator fitted on frame 11. N series Spitfires on all had the 12v regulator fitted in the well known position on frame 11 behind the headrest with the wiring protected by a metal shield and running down the port and starboard

side of the frame.

Edited by 19squadron
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Thanks very much Don,

 

I got the same TM view when I was looking for information in order to scratchbuild the battery. Your analysis confirmed what I concluded from the rare pictures.

 

It is nice to be able to collect all those information as the knowledge related to early Spitfires is full of gaps! If the Shacklady book is very good, all those aspects that are quite important to build an accurate model are alas simply ignored. <_<

 

Thierry

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On 3/4/2020 at 12:07 PM, thierry laurent said:

Well...

 

It looks I'm particularly gifted to question myself about obscure topics or items that should not be taken for granted too quickly...! ;-) Edgar, where are you...?

 

For some weird reasons, it is very difficult to find pictures of that device in situ whereas there are multiple airframes that were preserved and restored with that configuration (N3200, X4650, X4590, R6915 or P9444).

 

There's one good picture of Mk.Ia X4650 on Wikipedia (https://commons.wikimedia.org/wiki/File:Supermarine_Spitfire_I_‘X4650_-_KL-A’_(G-CGUK)_(40121560291).jpg#filelinks) but again that area is not very visible.

 

By the way, I also observed that system changed noticeably during the Spitfire long life. Initial Mk.Is had none. Than, the dome-shaped cylinder system appeared during the Mk.I run up to the beginning of Mk.II batches. It was then replaced by the more common double cylinder-shaped system. And finally it disappeared during production of the Mk.IX and on subsequent types.

 

The quest goes on...

 

 

Mk IX's were basically MkV's re engined, and retained most of the internal layout of the MkV including 24v regulators on the back of frame 11. Mk VII Mk VIII, MkXII and MkXIV etc were all total redesigns of all srtuctures bar C wings and all systems and they do not have any regulator mounted on the back of frame 11,

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