By: BobKat
- 14th February 2013 at 17:23Permalink- Edited 1st January 1970 at 01:00
Thanks Air Ministry - that's very helpful. I can't immediately identify ARI 5617. To what piece of equipment does this relate? Yet another use for Junction Box Type 25, it would appear!
..........
Air Ministry, I have it from the National Archives index - Monica Mk.III. Many thanks indeed, just what I was hoping for.
By: BobKat
- 15th February 2013 at 09:25Permalink- Edited 1st January 1970 at 01:00
Junction Box Type 25
The attached completes the picture of a splendid combined effort – many thanks to all those concerned, particularly the RAF Museum at Hendon for getting us on the right track with the details from AP1086, then WV-903 and the Duxford Radio Society people for their thoughts, Peter for the photographs, and finally Air Ministry for the diagram.
Another challenge for Laurent to find what, if anything, remains of the aerial!
Air Ministry,
Does your documentation have an AP number, or is it still recorded under its Secret Document (SD) reference as shown on the diagram? For future reference, would it be too much trouble to ask you to confirm whether the narrative (if you have it) lists all the major components with their AM reference numbers and, if so, whether you could let me know what they all are? I am specifically thinking of the Transmitter T3237, Receiver R3601, and Indicator Unit Type 116A, in addition to the Junction Box Type 25 which we already have and which would presumably be shown as 10AB/288 - and anything else listed.
By: Air Ministry
- 15th February 2013 at 13:18Permalink- Edited 1st January 1970 at 01:00
Here are the Stores Refs. for the major items of the system: there is no further breakdown of components except for the connectors which are listed in the photo I uploaded yesterday. Items such as Block, terminal, 3-way or Switch, Type B are common or garden items which might be from almost anywhere in the aeroplane so beware of declaring "Monica switch found!".
These lists relate to Monica IIIC and IIID. I looked this file up at Kew because my knowledge of systems such as Monica and Boozer is inadequate. The file does not indicate when/if this equipment came into widespread use. All it says is that it is intended to replace Monica I (perhaps development of M III leapfrogged M II?).
So it's possible that ED906 was flying with the earlier equipment, in which case some of these Stores Refs will be wrong. Thinking about it, don't the records held by DORIS list the equipment fitted to any particular airframe (Form 78 or 1180 - others on here will have a better knowledge of these things)?.
Anyway, that's about the sum total of what I can contribute on Monica. I didn't find that much at Kew but I intend to return to the search once the subjects of my current obsessions are exhausted.
By: BobKat
- 15th February 2013 at 14:47Permalink- Edited 1st January 1970 at 01:00
Very many thanks, Air Ministry, for the time and trouble you have taken in providing these details. I note your cautionary comments about switches and terminal blocks which could be from anywhere on the aircraft, but I think we can safely say that the Junction Box Type 25 with its reference number 10AB/288 is clearly listed as part of the Monica radar system.
I have a note that ED908 was equipped with IFF Mk.II (ARI 5025), Gee Mk.II (ARI 5083) and Oboe Mk.II (ARI 5582) when it was shot down. There is no mention of Monica, perhaps because its use on the aircraft had been discontinued following the discovery that Luftwaffe night-fighters were homing in on the broadcast – I don’t know exactly when in the summer of 1944 that would have been – but perhaps the receiver and transmitter had been removed, and maybe the aerial as well, just leaving the “permanent” connection point bolted to the fuselage? I can find little information about Monica Mk.II (ARI 5222 apparently with transmitter/receiver TR3207) and it would not be surprising if the Mk.III version (ARI 5617) replaced the Mk.I (ARI 5122), but unless some more pieces are found amongst the wreckage, we can only speculate as to which version was on board.
What seems to be apparent is that the Type 25 junction box was common to both systems.
By: Air Ministry
- 15th February 2013 at 15:55Permalink- Edited 1st January 1970 at 01:00
We had a good discussion on the forum about Bomber Command losses a few years ago but I can't find it now. I posted a graph showing bomber losses against significant events such as the introduction of Window, etc.
I'm pretty sure the order to cease using Monica came in August 1944 after the abilities of the Flendburg homing device fitted to the JU88 captured at Woodbridge had been proven to Harris. So, no reason why ED908 should not have Monica installed at the time it was shot down.
However, another possibility is that the aeroplane had been "plumbed" for Monica but the equipment had not been installed. This sometimes happened where the supply of equipment, manufactured on a small scale, was outstripped by the supply of airframes from several large factories.
Assuming your info about ED908 being fitted with H2S, Gee etc originated in DORIS, this may explain why you have no mention of Monica on the record card but a component at the crash site.
I don't suppose we'll know for sure unless Laurent unearths some new bits or an already recovered component is identified.
By: BobKat
- 16th February 2013 at 12:28Permalink- Edited 1st January 1970 at 01:00
An afterthought to the identification of the Monica aerial connection: we have both the junction box (seemingly bolted to a piece of fuselage, although the diagram suggests that the back plate is an integral part of the junction box) and the connecting socket for the antenna. If the aerial was not in place, then there would presumably be no need for the removable connecting socket still to be attached to the junction box. This would suggest that the Monica warning system was therefore on board the aircraft when it crashed.
Air Ministry mentioned DORIS (Department of Research & Information Services at the RAF Museum, Hendon) as a source of information for what equipment was on board. I have obtained Form 78 from them – this gives the history of the aircraft – built by AV Roe, with Merlin 28 engines, and its squadron allocations until reported missing, but nothing about the equipment on board. Curiously the information I have came from the personnel records of the Canadian mid-upper gunner! This was a marvellous source of information and included a copy of the telegram sent on 21 July 1944 from 582 Sqn to the Air Ministry. It gave the serial numbers of the engines and the airborne radar equipment carried, as well as details of the crew and their next-of-kin, etc. Much more information than is available from the UK personnel records released to members of the public (as distinct from next-of-kin). I have the Casualty report reference number (dealt with by No.1 MREU – the Missing Research & Enquiry Unit), but although there is a reference for these reports at the National Archives, they are not yet available for viewing.
I have some more information from France about item 33 (post #118). This piece was found close to the Monica junction box, so might well also have come from the rear turret area. It is made of copper or brass (“cuivre” translates as either!), is about 16mm, or a little more than half-an-inch, in diameter, and appears to be solid rather than hollow. It doesn’t seem likely to be part of the aerial if it is solid – maybe part of one of the guns???
By: WV-903.
- 16th February 2013 at 22:37Permalink- Edited 1st January 1970 at 01:00
Once again, great detection chaps.
Thanks for your thought, Peter. Maybe others will follow?
Air Ministry, that's a fascinating graph - many thanks for that. As you say it establishes that ED908 was likely to be carrying the Monica system.
Ow-eee !! again, ain't it a great feeling to get a gritty problem sorted by co-operation and help. Spitfire Ales all round and applause too. A bit late now, but here's a pic. of a new one of these Plugs. ED-908 's item probably had a lesser amount than 10 connecting holes and pins, at least this gives you an idea.
Looking forward to see what next our French stalwarts will find and the pics. we can scrutinize.
By: BobKat
- 18th February 2013 at 09:38Permalink- Edited 1st January 1970 at 01:00
Some identified items: 5 – Canopy/cupola framework
Thanks for your enthusiastic comments WV-903 – I will also have to try to find an appropriate Lancastrian brew with which to celebrate!
No more thoughts on item number 33 over the weekend. Most of the metal on the aircraft would presumably have been aluminium or steel. On the assumption that the piece has been correctly identified as being made of copper, then its use would most likely have been as a conductor of heat or electricity. What were those “H” shaped aerials used for, and would they have (what appears to be) a solid copper component? Or, changing tack completely, could it be part of a temperature measuring device???
It’s probably time to move on, but any more thoughts will be welcome.
Staying with the theme of gun turrets, this next item, number 27, was found some while ago, again not far from the Monica system junction box, so possibly from the rear turret? I have described it as an identified item, but it is slightly curious in that it does not quite seem to fit with the pictures I have managed to find of the main canopy and turret cupola framework.
The attached picture shows the piece photographed from both sides. It seems to be a double strip of metal bolted together with fragments of perspex, which protrude in both directions, attached on one side. It seems, therefore, not to be an edge piece that was attached to the main fuselage, but something from the central part of the canopy or cupola. Its bolts are placed off-centre, unlike pictures I have seen where they all, with one exception (see below), seem to be placed centrally.
If it is from the main canopy, I can’t see how it would have been attached to the spruce frame. If it was from the central part of a gun turret (if the rear, presumably the FN20), then would it not be expected to have bolt fittings extending on both sides of the metal strip? Here the perspex is attached by bolts passing straight through the metal strip, and the spacing between the bolts of the piece found looks a little closer than in the pictures I have seen of the FN20. At the right the perspex (seemingly intact with a straight edge) extends slightly, suggesting that this might be an upright piece and that the picture needs to be turned through 90 degrees to see how it might have fitted into the frame. The metal does not appear to have fragmented: if it has snapped, it was with a clean straight break. It has seven bolts along its length. It looks too short to be from the inboard end of the main rear turret frame of an FN20 turret and the bolts seem to be too closely spaced, although this is a point at which the perspex might overlap the metal strip?
I am drawn to the conclusion that it looks more like the upward frame from the inboard end an FN4 turret (pictured with acknowledgements to spitfirespares.com) which had a different style of framework, but I am not aware that these were ever fitted to the Lancaster. ED908 entered service in around April 1943 – perhaps early enough to have the old style of turret? It may be, of course, that I am wrong in my assumption that it was most likely to be from the rear turret, and it could be from one of the others – the FN5 front turret or the FN50 mid-upper turret, but neither of the structures of these seem to be quite right.
This is perhaps where turretboy’s knowledge would be of great help?
By: Peter
- 18th February 2013 at 15:50Permalink- Edited 1st January 1970 at 01:00
Bobkat.. another head scratcher..From the sketchy details gleaned from the picture, we can rule out rear cockpit canopy section which was made of wood. It almost looks like a cross brace section of the front canopy but this piece in the picture is flat not curved...
By: BobKat
- 18th February 2013 at 17:09Permalink- Edited 1st January 1970 at 01:00
Peter, sorry to be the cause of more head scratching!!!
I have previously tried to find some close up pictures of the canopy in sufficient detail to show the bolt placings on the cross braces and supports, but so far without success. Nothing that I have found looks quite the same as what we have, except on the FN4 turret pictured.....
Do you (or does anybody) know if this turret was ever fitted to the early Lancasters? If so, then this would seem to be a possible answer.
By: BobKat
- 19th February 2013 at 10:33Permalink- Edited 1st January 1970 at 01:00
Peter , exactly as you say – it has no metal tabs, and that is what has left me wondering.
turretboy, many thanks for your comments. I assume you have no further thoughts about our piece 31 following my post #142? (This may be complicated by the fact that we might have an FN4 turret).
As I understand it, the FN120 was a variant on the FN20 turret introduced in late 1944. The Lancaster Manual (AP2062A) of May 1944 refers to the FN20 turret which, at that time, was presumably the standard rear turret fitting. As far as I can tell, its metal framework is quite different to what we are looking at – bolts more widely spaced, etc.
ED908 was built by AV Roe as part of a batch of mixed Mk.I and Mk.III Lancasters and was completed in around April 1943. I can find no reference to the FN4 turret ever being used on the Lancaster, but I suppose it could just be that some of this early batch of aircraft were fitted with the last remaining FN4 turrets previously used on the Manchester??
It is the picture below that I find so convincing. Everything looks right about the upright part on the right – the width of the metal, the spacing between the bolts, and their being offset to one side. Our piece is clearly not one of the lateral or diagonal supports – one has metal tabs, and they are both thinner with their bolts placed centrally. It is that bit of perspex that is sticking out to the right on our piece that seems odd. Could it be that the perspex overlapped the metalwork by a fraction to help provide a “snug” (??) fit to the door frame?
By: Air Ministry
- 19th February 2013 at 14:34Permalink- Edited 1st January 1970 at 01:00
Hi Bobkat,
I'm with turretboy on this. Although I can see the similarity, I cannot match your piece to a Lancaster turret.
For my credentials, I own a Lancaster front turret and several mid-uppers so I'm pretty familiar with Frazer Nash construction.
Your description "a double strip of metal bolted together with fragments of perspex" doesn't ring any bells with me.
Besides the turrets, I have just about every A.P. (Vol I) for F.N. turrets. One of the useful things each one contains is a diagram showing the attachment of perspex to the cupola, with cross sections of each method. I've checked all the Lanc ones and, just for fun, the FN4 too. None of them appear to have the type of arrangement you've described.
Apart from the prototype, I am convinced no Lancaster was ever fitted with the FN4 turret. (Incidentally though, I did read correspondence between Harris and the "turret people" at the Ministry in which he severely criticised the lack of vision out of the FN20, comparing it unfavourably with the FN4.)
Which brings about the question of "mods" on the unit. I've studied enough rear turret photographs to know that many received mods, some official but many unofficial ones too, especially to address the rearward vision problem: sliding sections which could be opened to give direct vision, whole areas of perspex simply removed, etc. It would be difficult to make sense of your mystery part in that context though, as the perspex extends beyond each side of the metal strip, suggesting it's not part of some sliding or detachable piece.
Could it be from the main canopy? Well, I'm fortunate to have one of those too. The rear half is wooden as already stated and the front half is assembled out of circular section tubing for the main part, so your part doesn't match either.
Which leads us to puzzle over what exactly it might be. I think you'll have to reassign it to the "unidentified" pile for now. Maybe another piece with more clues will turn up eventually?
By: BobKat
- 19th February 2013 at 15:02Permalink- Edited 1st January 1970 at 01:00
Air Ministry,
That was pretty emphatic – many thanks – good to have an authoritative source! The best we seem to be able to come up with is that it might be related to a repair or modification to a perspex covering.
One thing that can be said is that the metal strip seems to match that used on the FN4 turret, and that would lend some credence to the theory that it could be a repair using available metal parts, and therefore possibly turret related.
Back to the “unidentified” box it seems to have to go!!
Posts: 10,167
By: Peter - 14th February 2013 at 15:43 Permalink - Edited 1st January 1970 at 01:00
Yes that item in post 118 is a solid metal fitting of some sort. I imagine the antenna would be hollow for wiring to run through.
Posts: 1,918
By: Air Ministry - 14th February 2013 at 16:55 Permalink - Edited 1st January 1970 at 01:00
This should help...
Posts: 936
By: BobKat - 14th February 2013 at 17:23 Permalink - Edited 1st January 1970 at 01:00
Thanks Air Ministry - that's very helpful. I can't immediately identify ARI 5617. To what piece of equipment does this relate? Yet another use for Junction Box Type 25, it would appear!
..........
Air Ministry, I have it from the National Archives index - Monica Mk.III. Many thanks indeed, just what I was hoping for.
Posts: 936
By: BobKat - 15th February 2013 at 09:25 Permalink - Edited 1st January 1970 at 01:00
Junction Box Type 25
The attached completes the picture of a splendid combined effort – many thanks to all those concerned, particularly the RAF Museum at Hendon for getting us on the right track with the details from AP1086, then WV-903 and the Duxford Radio Society people for their thoughts, Peter for the photographs, and finally Air Ministry for the diagram.
Another challenge for Laurent to find what, if anything, remains of the aerial!
Air Ministry,
Does your documentation have an AP number, or is it still recorded under its Secret Document (SD) reference as shown on the diagram? For future reference, would it be too much trouble to ask you to confirm whether the narrative (if you have it) lists all the major components with their AM reference numbers and, if so, whether you could let me know what they all are? I am specifically thinking of the Transmitter T3237, Receiver R3601, and Indicator Unit Type 116A, in addition to the Junction Box Type 25 which we already have and which would presumably be shown as 10AB/288 - and anything else listed.
Posts: 1,918
By: Air Ministry - 15th February 2013 at 13:18 Permalink - Edited 1st January 1970 at 01:00
Here are the Stores Refs. for the major items of the system: there is no further breakdown of components except for the connectors which are listed in the photo I uploaded yesterday. Items such as Block, terminal, 3-way or Switch, Type B are common or garden items which might be from almost anywhere in the aeroplane so beware of declaring "Monica switch found!".
These lists relate to Monica IIIC and IIID. I looked this file up at Kew because my knowledge of systems such as Monica and Boozer is inadequate. The file does not indicate when/if this equipment came into widespread use. All it says is that it is intended to replace Monica I (perhaps development of M III leapfrogged M II?).
So it's possible that ED906 was flying with the earlier equipment, in which case some of these Stores Refs will be wrong. Thinking about it, don't the records held by DORIS list the equipment fitted to any particular airframe (Form 78 or 1180 - others on here will have a better knowledge of these things)?.
Anyway, that's about the sum total of what I can contribute on Monica. I didn't find that much at Kew but I intend to return to the search once the subjects of my current obsessions are exhausted.
Posts: 936
By: BobKat - 15th February 2013 at 14:47 Permalink - Edited 1st January 1970 at 01:00
Very many thanks, Air Ministry, for the time and trouble you have taken in providing these details. I note your cautionary comments about switches and terminal blocks which could be from anywhere on the aircraft, but I think we can safely say that the Junction Box Type 25 with its reference number 10AB/288 is clearly listed as part of the Monica radar system.
I have a note that ED908 was equipped with IFF Mk.II (ARI 5025), Gee Mk.II (ARI 5083) and Oboe Mk.II (ARI 5582) when it was shot down. There is no mention of Monica, perhaps because its use on the aircraft had been discontinued following the discovery that Luftwaffe night-fighters were homing in on the broadcast – I don’t know exactly when in the summer of 1944 that would have been – but perhaps the receiver and transmitter had been removed, and maybe the aerial as well, just leaving the “permanent” connection point bolted to the fuselage? I can find little information about Monica Mk.II (ARI 5222 apparently with transmitter/receiver TR3207) and it would not be surprising if the Mk.III version (ARI 5617) replaced the Mk.I (ARI 5122), but unless some more pieces are found amongst the wreckage, we can only speculate as to which version was on board.
What seems to be apparent is that the Type 25 junction box was common to both systems.
Thanks again for your help.
Posts: 1,918
By: Air Ministry - 15th February 2013 at 15:55 Permalink - Edited 1st January 1970 at 01:00
We had a good discussion on the forum about Bomber Command losses a few years ago but I can't find it now. I posted a graph showing bomber losses against significant events such as the introduction of Window, etc.
I'm pretty sure the order to cease using Monica came in August 1944 after the abilities of the Flendburg homing device fitted to the JU88 captured at Woodbridge had been proven to Harris. So, no reason why ED908 should not have Monica installed at the time it was shot down.
However, another possibility is that the aeroplane had been "plumbed" for Monica but the equipment had not been installed. This sometimes happened where the supply of equipment, manufactured on a small scale, was outstripped by the supply of airframes from several large factories.
Assuming your info about ED908 being fitted with H2S, Gee etc originated in DORIS, this may explain why you have no mention of Monica on the record card but a component at the crash site.
I don't suppose we'll know for sure unless Laurent unearths some new bits or an already recovered component is identified.
Posts: 936
By: BobKat - 16th February 2013 at 12:28 Permalink - Edited 1st January 1970 at 01:00
An afterthought to the identification of the Monica aerial connection: we have both the junction box (seemingly bolted to a piece of fuselage, although the diagram suggests that the back plate is an integral part of the junction box) and the connecting socket for the antenna. If the aerial was not in place, then there would presumably be no need for the removable connecting socket still to be attached to the junction box. This would suggest that the Monica warning system was therefore on board the aircraft when it crashed.
Air Ministry mentioned DORIS (Department of Research & Information Services at the RAF Museum, Hendon) as a source of information for what equipment was on board. I have obtained Form 78 from them – this gives the history of the aircraft – built by AV Roe, with Merlin 28 engines, and its squadron allocations until reported missing, but nothing about the equipment on board. Curiously the information I have came from the personnel records of the Canadian mid-upper gunner! This was a marvellous source of information and included a copy of the telegram sent on 21 July 1944 from 582 Sqn to the Air Ministry. It gave the serial numbers of the engines and the airborne radar equipment carried, as well as details of the crew and their next-of-kin, etc. Much more information than is available from the UK personnel records released to members of the public (as distinct from next-of-kin). I have the Casualty report reference number (dealt with by No.1 MREU – the Missing Research & Enquiry Unit), but although there is a reference for these reports at the National Archives, they are not yet available for viewing.
I have some more information from France about item 33 (post #118). This piece was found close to the Monica junction box, so might well also have come from the rear turret area. It is made of copper or brass (“cuivre” translates as either!), is about 16mm, or a little more than half-an-inch, in diameter, and appears to be solid rather than hollow. It doesn’t seem likely to be part of the aerial if it is solid – maybe part of one of the guns???
Any ideas, anyone?
Posts: 10,167
By: Peter - 16th February 2013 at 15:04 Permalink - Edited 1st January 1970 at 01:00
First thought would be the elevation rams for the guns but sadly no as they were stainless..
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By: Air Ministry - 16th February 2013 at 15:23 Permalink - Edited 1st January 1970 at 01:00
I found the graph I referred to a couple of posts above:-
http://forum.keypublishing.co.uk/attachment.php?attachmentid=181089&d=1264677604
The last but one of the vertical entries at the top of the graph reads "Monica restricted" and confirms this was done some time after ED908 was lost.
Another small piece of the puzzle I suppose.
Posts: 936
By: BobKat - 16th February 2013 at 16:07 Permalink - Edited 1st January 1970 at 01:00
Thanks for your thought, Peter. Maybe others will follow?
Air Ministry, that's a fascinating graph - many thanks for that. As you say it establishes that ED908 was likely to be carrying the Monica system.
Posts: 564
By: WV-903. - 16th February 2013 at 22:37 Permalink - Edited 1st January 1970 at 01:00
Once again, great detection chaps.
Ow-eee !! again, ain't it a great feeling to get a gritty problem sorted by co-operation and help. Spitfire Ales all round and applause too. A bit late now, but here's a pic. of a new one of these Plugs. ED-908 's item probably had a lesser amount than 10 connecting holes and pins, at least this gives you an idea.
Looking forward to see what next our French stalwarts will find and the pics. we can scrutinize.
Bill T.
Posts: 936
By: BobKat - 18th February 2013 at 09:38 Permalink - Edited 1st January 1970 at 01:00
Some identified items: 5 – Canopy/cupola framework
Thanks for your enthusiastic comments WV-903 – I will also have to try to find an appropriate Lancastrian brew with which to celebrate!
No more thoughts on item number 33 over the weekend. Most of the metal on the aircraft would presumably have been aluminium or steel. On the assumption that the piece has been correctly identified as being made of copper, then its use would most likely have been as a conductor of heat or electricity. What were those “H” shaped aerials used for, and would they have (what appears to be) a solid copper component? Or, changing tack completely, could it be part of a temperature measuring device???
It’s probably time to move on, but any more thoughts will be welcome.
Staying with the theme of gun turrets, this next item, number 27, was found some while ago, again not far from the Monica system junction box, so possibly from the rear turret? I have described it as an identified item, but it is slightly curious in that it does not quite seem to fit with the pictures I have managed to find of the main canopy and turret cupola framework.
The attached picture shows the piece photographed from both sides. It seems to be a double strip of metal bolted together with fragments of perspex, which protrude in both directions, attached on one side. It seems, therefore, not to be an edge piece that was attached to the main fuselage, but something from the central part of the canopy or cupola. Its bolts are placed off-centre, unlike pictures I have seen where they all, with one exception (see below), seem to be placed centrally.
If it is from the main canopy, I can’t see how it would have been attached to the spruce frame. If it was from the central part of a gun turret (if the rear, presumably the FN20), then would it not be expected to have bolt fittings extending on both sides of the metal strip? Here the perspex is attached by bolts passing straight through the metal strip, and the spacing between the bolts of the piece found looks a little closer than in the pictures I have seen of the FN20. At the right the perspex (seemingly intact with a straight edge) extends slightly, suggesting that this might be an upright piece and that the picture needs to be turned through 90 degrees to see how it might have fitted into the frame. The metal does not appear to have fragmented: if it has snapped, it was with a clean straight break. It has seven bolts along its length. It looks too short to be from the inboard end of the main rear turret frame of an FN20 turret and the bolts seem to be too closely spaced, although this is a point at which the perspex might overlap the metal strip?
I am drawn to the conclusion that it looks more like the upward frame from the inboard end an FN4 turret (pictured with acknowledgements to spitfirespares.com) which had a different style of framework, but I am not aware that these were ever fitted to the Lancaster. ED908 entered service in around April 1943 – perhaps early enough to have the old style of turret? It may be, of course, that I am wrong in my assumption that it was most likely to be from the rear turret, and it could be from one of the others – the FN5 front turret or the FN50 mid-upper turret, but neither of the structures of these seem to be quite right.
This is perhaps where turretboy’s knowledge would be of great help?
Posts: 10,167
By: Peter - 18th February 2013 at 15:50 Permalink - Edited 1st January 1970 at 01:00
Bobkat.. another head scratcher..From the sketchy details gleaned from the picture, we can rule out rear cockpit canopy section which was made of wood. It almost looks like a cross brace section of the front canopy but this piece in the picture is flat not curved...
Posts: 936
By: BobKat - 18th February 2013 at 17:09 Permalink - Edited 1st January 1970 at 01:00
Peter, sorry to be the cause of more head scratching!!!
I have previously tried to find some close up pictures of the canopy in sufficient detail to show the bolt placings on the cross braces and supports, but so far without success. Nothing that I have found looks quite the same as what we have, except on the FN4 turret pictured.....
Do you (or does anybody) know if this turret was ever fitted to the early Lancasters? If so, then this would seem to be a possible answer.
Posts: 10,167
By: Peter - 18th February 2013 at 23:35 Permalink - Edited 1st January 1970 at 01:00
If it was turret Bobkat, it should have those metal tabs on it..
Posts: 562
By: turretboy - 19th February 2013 at 01:17 Permalink - Edited 1st January 1970 at 01:00
All Perspex on the FN120/121 turret is bolted to the internal framing made of aluminum square tube and a bent aluminum angle along the base.
I'm quite sure this is the case for most FN type turrets.
Posts: 936
By: BobKat - 19th February 2013 at 10:33 Permalink - Edited 1st January 1970 at 01:00
Peter , exactly as you say – it has no metal tabs, and that is what has left me wondering.
turretboy, many thanks for your comments. I assume you have no further thoughts about our piece 31 following my post #142? (This may be complicated by the fact that we might have an FN4 turret).
As I understand it, the FN120 was a variant on the FN20 turret introduced in late 1944. The Lancaster Manual (AP2062A) of May 1944 refers to the FN20 turret which, at that time, was presumably the standard rear turret fitting. As far as I can tell, its metal framework is quite different to what we are looking at – bolts more widely spaced, etc.
ED908 was built by AV Roe as part of a batch of mixed Mk.I and Mk.III Lancasters and was completed in around April 1943. I can find no reference to the FN4 turret ever being used on the Lancaster, but I suppose it could just be that some of this early batch of aircraft were fitted with the last remaining FN4 turrets previously used on the Manchester??
It is the picture below that I find so convincing. Everything looks right about the upright part on the right – the width of the metal, the spacing between the bolts, and their being offset to one side. Our piece is clearly not one of the lateral or diagonal supports – one has metal tabs, and they are both thinner with their bolts placed centrally. It is that bit of perspex that is sticking out to the right on our piece that seems odd. Could it be that the perspex overlapped the metalwork by a fraction to help provide a “snug” (??) fit to the door frame?
Hmmm ..... more head scratching I fear!
Posts: 1,918
By: Air Ministry - 19th February 2013 at 14:34 Permalink - Edited 1st January 1970 at 01:00
Hi Bobkat,
I'm with turretboy on this. Although I can see the similarity, I cannot match your piece to a Lancaster turret.
For my credentials, I own a Lancaster front turret and several mid-uppers so I'm pretty familiar with Frazer Nash construction.
Your description "a double strip of metal bolted together with fragments of perspex" doesn't ring any bells with me.
Besides the turrets, I have just about every A.P. (Vol I) for F.N. turrets. One of the useful things each one contains is a diagram showing the attachment of perspex to the cupola, with cross sections of each method. I've checked all the Lanc ones and, just for fun, the FN4 too. None of them appear to have the type of arrangement you've described.
Apart from the prototype, I am convinced no Lancaster was ever fitted with the FN4 turret. (Incidentally though, I did read correspondence between Harris and the "turret people" at the Ministry in which he severely criticised the lack of vision out of the FN20, comparing it unfavourably with the FN4.)
Which brings about the question of "mods" on the unit. I've studied enough rear turret photographs to know that many received mods, some official but many unofficial ones too, especially to address the rearward vision problem: sliding sections which could be opened to give direct vision, whole areas of perspex simply removed, etc. It would be difficult to make sense of your mystery part in that context though, as the perspex extends beyond each side of the metal strip, suggesting it's not part of some sliding or detachable piece.
Could it be from the main canopy? Well, I'm fortunate to have one of those too. The rear half is wooden as already stated and the front half is assembled out of circular section tubing for the main part, so your part doesn't match either.
Which leads us to puzzle over what exactly it might be. I think you'll have to reassign it to the "unidentified" pile for now. Maybe another piece with more clues will turn up eventually?
Posts: 936
By: BobKat - 19th February 2013 at 15:02 Permalink - Edited 1st January 1970 at 01:00
Air Ministry,
That was pretty emphatic – many thanks – good to have an authoritative source! The best we seem to be able to come up with is that it might be related to a repair or modification to a perspex covering.
One thing that can be said is that the metal strip seems to match that used on the FN4 turret, and that would lend some credence to the theory that it could be a repair using available metal parts, and therefore possibly turret related.
Back to the “unidentified” box it seems to have to go!!