christian Boehm Posted October 26, 2018 Share Posted October 26, 2018 Hi everybody I am back with my Blenheim upgrading questions about building both Mk I and IV for replacement of my “old” Frog and Airfix models . Actually the “new” Airfix kit is quite a good one in many approaches but not so fantastic as one’s waiting for … See particularly the interesting option of closed or open cowl flaps: I choose the opens ones but was surprised by raising lines between each flap ; if someone wants engraved lines , that really must be these ones, not ? I had to engrave all flaps separations. About the Mk IV, I want to build a desert plane including specially the so called “chin” blister nose underside rear firing turret; it’s the Frazer – Nash FN 54-A model and there are some obscure things about this stuff. I admit it would be operated through the nose inside, as for the compact Frazer – Nash FN 54 (as indicated in the very good book “British Aircraft Armament – from Wallace-Clarke , page 131) But unfortunately this book doesn’t tell anything about the plexiglas FN 54A chin turret ! How was it inside the cockpit ? Probably the same telescopic periscop sight control column ? But it’s impossible to imagine a folding seat over that clear blister as on the compact turret, or … ? A photo on page 66 of Valiant Ed Airframe Album n°5 shows the extracted turret and doesn’t help a lot. Does anybody know more on how it looked like inside ? Thanks a lot Christian Link to comment Share on other sites More sharing options...
Tweener Posted October 26, 2018 Share Posted October 26, 2018 41 minutes ago, christian Boehm said: Hi everybody I am back with my Blenheim upgrading questions about building both Mk I and IV for replacement of my “old” Frog and Airfix models . Actually the “new” Airfix kit is quite a good one in many approaches but not so fantastic as one’s waiting for … See particularly the interesting option of closed or open cowl flaps: I choose the opens ones but was surprised by raising lines between each flap ; if someone wants engraved lines , that really must be these ones, not ? I had to engrave all flaps separations. About the Mk IV, I want to build a desert plane including specially the so called “chin” blister nose underside rear firing turret; it’s the Frazer – Nash FN 54-A model and there are some obscure things about this stuff. I admit it would be operated through the nose inside, as for the compact Frazer – Nash FN 54 (as indicated in the very good book “British Aircraft Armament – from Wallace-Clarke , page 131) But unfortunately this book doesn’t tell anything about the plexiglas FN 54A chin turret ! How was it inside the cockpit ? Probably the same telescopic periscop sight control column ? But it’s impossible to imagine a folding seat over that clear blister as on the compact turret, or … ? A photo on page 66 of Valiant Ed Airframe Album n°5 shows the extracted turret and doesn’t help a lot. Does anybody know more on how it looked like inside ? Thanks a lot Christian I have been wondering about this myself. I will see what I can find, and at the very least, will be following this. Do you know if it was a similar turret to the Mark V? Link to comment Share on other sites More sharing options...
Ivor Ramsden Posted October 27, 2018 Share Posted October 27, 2018 The engine cooling gills on the Blenheim's engines are not separated by gaps when open. Between each gill is a narrow plate which covers the gap so engraved lines are not correct; the plates are correctly and neatly represented in the kit. 4 Link to comment Share on other sites More sharing options...
Graham Boak Posted October 27, 2018 Share Posted October 27, 2018 The transparent blister mounting for a single gun was not Frazer Nash but a Bristol design. Apparently it was not a turret but a fixed fairing and the gun could be depressed but not traversed. The twin gun mounting was the FN54 and could be depressed and traversed. There has been some discussion about the designations FH54/54A. It would seem logical to me that the term FN54A refers to the faired version on the Blenheim Mk.V, but I've not seen any definitive statement. Google brings up a thread on Flypast's Historical aircraft forum, including a reference to a Frazer Nash history which may say more. Link to comment Share on other sites More sharing options...
Selwyn Posted October 27, 2018 Share Posted October 27, 2018 (edited) 22 minutes ago, Graham Boak said: The transparent blister mounting for a single gun was not Frazer Nash but a Bristol design. Apparently it was not a turret but a fixed fairing and the gun could be depressed but not traversed. The twin gun mounting was the FN54 and could be depressed and traversed. There has been some discussion about the designations FH54/54A. It would seem logical to me that the term FN54A refers to the faired version on the Blenheim Mk.V, but I've not seen any definitive statement. Google brings up a thread on Flypast's Historical aircraft forum, including a reference to a Frazer Nash history which may say more. Graham is correct it was a Bristol design, the perspex blister is correctly called the Beaufort blister mounting as it was actually designed for that aircraft. When it was identified that the Blenheim urgently needed under fuselage protection it was already in existence and a convenient quick fix for the problem pending the design of the purpose made FN 54 twin turret. The nose of the Blenheim and Beaufort had a great deal of design commonality, especially in relation to the dimensions of their respective under nose emergency hatches (which gave a mounting point for the installation). For crew escape both the beaufort blister and the FN54 were jettisonable in an emergency. There was never a FN 54A turret despite what you might read in various publications, although this mounting was developed further into the rarely seen FN 64 under fuselage mounting for the Lancaster bomber. If you look at wallace clarkes book “British Aircraft Armament " there is a correctly captioned picture of the Beaufort blister right next to the FN 54 illustration! Selwyn Edited October 27, 2018 by Selwyn 2 Link to comment Share on other sites More sharing options...
christian Boehm Posted October 28, 2018 Author Share Posted October 28, 2018 Hello all again First I have really to apologize …. Ivor is totally right : the Blenheim engine cooling gills are not separated by gaps when open. I was totally blinded by the usually separated gills on main planes and didn’t watch enough seriously the pictures. So now I found on my docs the gills covered by a thin plate in any case. Thanks a lot Ivor. Secondly sorry again for too less research and thanks to Graham and Selwyn Again you’re right. I opened my Wallace- Clarke -turret boo k again and found on page 35 the actually Bristol chin turret , false named Frazer Nash 54A in other publications; as well I founded it on Beaufort docs ‘ specially good shots in Bruce Robertson Ian Allan book) , although , as I read, it was rarely set on this aircraft. There is a drawing showing how the operator had to lie down to sight and fire (after folding his navigator seat as I believe) I will try to fit the turret as faith I can on the kit. So thanks to all for helping ! I am happy to travel to Telford in 2 weeks ( third time , always amazing experience)…. Christian 2 Link to comment Share on other sites More sharing options...
larumivi1951 Posted October 29, 2018 Share Posted October 29, 2018 Picture of the Nash FN 54 turret: Rudolph 1 Link to comment Share on other sites More sharing options...
Graham Boak Posted October 29, 2018 Share Posted October 29, 2018 (edited) The source is wrong because it shows the Bristol gun position, which is not a turret anyway. I would also suggest that the differences between the two were so significant as to require a different designation, not just a suffix. Edited October 29, 2018 by Graham Boak Link to comment Share on other sites More sharing options...
christian Boehm Posted October 29, 2018 Author Share Posted October 29, 2018 Thanks Larumivi That's exactly what I had ( in that bbok) and why I thought there are (54 and 54A Fraer nash) posts. And Graham is riht : this is a wrong interpration Link to comment Share on other sites More sharing options...
christian Boehm Posted October 29, 2018 Author Share Posted October 29, 2018 (… sorry gone too fast) … wrong interpretation . The only FN 54 was the compact one and the real Builder is Bristol , not FN ; You will find the proof in Wallace Clarkes book on british armament. Eventually and although these photos show the shape of the gun mechanism , it remains obscur how the cockpit floor ( actually the escape hatch part) was amended to permit sighting an,d firing I think I will pearce a small opening range with a sight column Inside the cabin ( (I read this column was telescopic for the FN 5' ; it must be the same for this one …?) Christian Link to comment Share on other sites More sharing options...
Walter Lindekens Posted October 29, 2018 Share Posted October 29, 2018 Hi Christian & all, As correctly pointed out above the under-nose blister mounting on the Blenheim Mk IV was an adaptation of the undernose blister mounting developed by Bristol's for the Beaufort. The Frazer-Nash FN 54A was a completely different design, by Frazer-Nash's as its name says. In Air Publication 1659B, VOL 1, which covers Bristol turrets the under-nose blister is referred to as "The Blenheim IV Under Defence Turret, Single Gun". Whether it is a true "turret" I will leave open to debate :). As pointed out by Graham there has been some discussion about the FN 54/FN 54A designation but Bristol Blenheim IV Modification Leaflet 1073 describes the fitting of the FN54A twin under defence gun mounting. If there ever was an FN 54B I do not know, The Air Publication for the Blenheim Mk V simply refers to the under defence gun mounting without specifying the exact type. Correctly portraying the blister gun on a model takes more than simply sticking on a blister under the nose but as pointed out by Christian it is dificult to find details of what was actually going on inside the nose of the aircraft when the blister was fitted so I hope these images out of AP1659B may be of interest: Cheers, Walter 3 5 Link to comment Share on other sites More sharing options...
Seahawk Posted October 29, 2018 Share Posted October 29, 2018 6 hours ago, christian Boehm said: The only FN 54 was the compact one and the real Builder is Bristol , not FN ; You will find the proof in Wallace Clarkes book on british armament. Think you have slightly misconstrued what Clarke is saying on p.130 of his book (1st Vol). The story is: Parnall, based at Yate near Bristol, were issued with "an urgent request to provide some means of under-defence for [Blenheims]"; "A Blenheim was flown into Yate, complete with structural drawings"; At the same time a "small design team from Tolworth" [Frazer-Nash's design office near the Kingston bypass], arrived "to make an on-the-spot assessment. They submitted a design for a twin Browning installation mounted under the nose, manually controlled by the bomb aimer"; "The company [Frazer-Nash] was instructed to proceed with a prototype with the greatest urgency"; "Work started at Tolworth [ie chez Frazer-Nash] immediately and the turret was given the [Frazer-Nash] Type number FN54." Earlier (p.92) Clarke explains that Frazer-Nash had taken over Parnall's Yate factory to provide the increased production facilities that would be needed in wartime, with the design and development teams remaining at Tolworth. So the whole task took place under the Frazer-Nash umbrella, with Bristol's role limited to the loan of a Blenheim and the structural drawings. Link to comment Share on other sites More sharing options...
Graham Boak Posted October 29, 2018 Share Posted October 29, 2018 A listing of Bristol powered gun turrets does not include the fixed transparent cupola, as it was neither powered or a turret. It does not traverse, which is something of a requirement of a turret in gunnery terms. Obviously not in the case of castles and other pieces of architecture. Link to comment Share on other sites More sharing options...
dogsbody Posted October 29, 2018 Share Posted October 29, 2018 2 hours ago, Walter Lindekens said: Hi Christian & all, As correctly pointed out above the under-nose blister mounting on the Blenheim Mk IV was an adaptation of the undernose blister mounting developed by Bristol's for the Beaufort. The Frazer-Nash FN 54A was a completely different design, by Frazer-Nash's as its name says. In Air Publication 1659B, VOL 1, which covers Bristol turrets the under-nose blister is referred to as "The Blenheim IV Under Defence Turret, Single Gun". Whether it is a true "turret" I will leave open to debate :). As pointed out by Graham there has been some discussion about the FN 54/FN 54A designation but Bristol Blenheim IV Modification Leaflet 1073 describes the fitting of the FN54A twin under defence gun mounting. If there ever was an FN 54B I do not know, The Air Publication for the Blenheim Mk V simply refers to the under defence gun mounting without specifying the exact type. Correctly portraying the blister gun on a model takes more than simply sticking on a blister under the nose but as pointed out by Christian it is dificult to find details of what was actually going on inside the nose of the aircraft when the blister was fitted so I hope these images out of AP1659B may be of interest: Cheers, Walter Bravo, Walter! This it the first time that I have ever seen these images and they really show the Bristol rear gun fairing. Chris 2 Link to comment Share on other sites More sharing options...
christian Boehm Posted October 29, 2018 Author Share Posted October 29, 2018 yes Dogsbody I was just reading with attention Walter's text and watching with high interest his drawings I agree totally with you Dogs and congratulations to Walter for sending this message It's interesting to know , for the theory , which and how companies set out this gunnery. Was it FN or Bristol , ok, but that's a second hand question And , considering the modeller's practice , I also minded that simply sticking a blister under the noseopening was not the way. So I finally see what I have to do on the kit : a credible hole in the hatch Under the blister , setting ammunition box, asf ; the pictures show all you need And finally, about Walter's Drawings , it's just an example that google is fantastic but never perfect ! Above that comes the modeller's chating , with their docs stools, through good forums as ours , not ? thanks +++ christian 1 Link to comment Share on other sites More sharing options...
dogsbody Posted November 2, 2018 Share Posted November 2, 2018 I see that the Airfix Blenheim Mk.IV kit comes with parts for both under-nose gun fittings. Chris 1 Link to comment Share on other sites More sharing options...
JPuente54 Posted November 3, 2018 Share Posted November 3, 2018 @dogsbody, Chris, I just read your post, and checked my kit; they are there. I believe that part D7 is the "base" for the single gun fairing. Joe 1 Link to comment Share on other sites More sharing options...
christian Boehm Posted November 3, 2018 Author Share Posted November 3, 2018 Hi Chris and Joe You're rigfht both underisde re Link to comment Share on other sites More sharing options...
christian Boehm Posted November 3, 2018 Author Share Posted November 3, 2018 …. following , sorry Hi Chris and Joe You're right Both underside rear firing posts are included in the H clear sprue ( Mk IV kit) specially as H2 for the "chin" and H7 for the FN 54 ( the last one has of course to be painted) And a part D7 comes for for the chin but it's very crude , without open space to Inside and, for me, inadequate Our above discussions were only about how operating of these posts were in the cockpit Inside range. About the FN54 compact one, the Wallace Clarke book is very useful but for the chin post , Chris's docs (dogsbody) broughtabove were goldworth ! christian PS : I will come again to you all later about other detail kit's imperfections I realized Link to comment Share on other sites More sharing options...
christian Boehm Posted November 3, 2018 Author Share Posted November 3, 2018 Here I am back Some other remarks about building 1) about the omitted escape hatch with circular window behind the bomb bay , I add them on both Mk I and IV ; see these exchanges https://www.britmodeller.com/forums/index.php?/topic/235043655-blenheim-fuselage-underside/&tab=comments#comment-3139002 2) On the kit's front cowling rings , you will find - first 2 bulges covering the exhausts tubes - on them a small and fine hollow tube Studying dozens of pictures I didn't find these 2 fittings anywhere, exept on canadian built Blenheims and on some restored museum planes . So I deleted it all Anyway it's nor on my planed RO ° P Blenheim Mk I and nor on my planed 14 squadron MTO Mk IV see this film : https://youtu.be/dz2wGymCE_U 3) About the 14 squadron , the plane "W" Z5893 had the chin clear fire post but the plane "N" had the compact FN 54 ; I have good shots of both Again note the Z5893 was the "W" plane (and not the "N" like in Xtradecals sheet) ; the "N" was Z7631 Link to comment Share on other sites More sharing options...
dogsbody Posted November 3, 2018 Share Posted November 3, 2018 Yes, Christian, those small tubes on Canadian-made Blenheims/Bollingbrokes are for additional cockpit and other heating. It can get quite cold here in Canada. I have personally worked outside when the windchill was -65C. Let me tell you clearly, that is thumb sucking cold! The Blenheim that is flying in the UK now and was used by Airfix to make their moulds is an airframe that originally came from Canada. It still has some of the features of that long-ago Canadian production. Chris Link to comment Share on other sites More sharing options...
Mi Tasol Posted August 24, 2020 Share Posted August 24, 2020 Walter Lindekens posted a number of pages from Air Publication 1659B, VOL 1 on October 30, 2018 These pages covered the Blenheim/Beaufort under defense gun and are no longer available on that post. Did anyone copy and save these photos and if so can they please post them back on this thread Alternatively does anyone know of any digital copy of AP 1659B that they can point me to. Thanks in advance Link to comment Share on other sites More sharing options...
Mi Tasol Posted August 24, 2020 Share Posted August 24, 2020 Graham Boak posted October 30, 2018 that A listing of Bristol powered gun turrets does not include the fixed transparent cupola, as it was neither powered or a turret. It does not traverse, which is something of a requirement of a turret in gunnery terms. While I cannot speak for the Blenheim turret the Australian Beaufort under defense gun most definitely does both elevate and traverse although only through a very limited range. I agree though that it is not a turret. Overall I would clasify it as an aerodynamic brake with little if any defensive ability (except to maybe give the enemy a good laugh). Link to comment Share on other sites More sharing options...
brewerjerry Posted August 24, 2020 Share Posted August 24, 2020 (edited) 36 minutes ago, Mi Tasol said: Walter Lindekens posted a number of pages from Air Publication 1659B, VOL 1 on October 30, 2018 These pages covered the Blenheim/Beaufort under defense gun and are no longer available on that post. Did anyone copy and save these photos and if so can they please post them back on this thread Alternatively does anyone know of any digital copy of AP 1659B that they can point me to. Thanks in advance Hi google brings this https://www.flickr.com/photos/wwrsimon/50011402843/in/photostream cheers jerry Edited August 24, 2020 by brewerjerry Link to comment Share on other sites More sharing options...
dogsbody Posted August 24, 2020 Share Posted August 24, 2020 I got these: Chris 6 1 Link to comment Share on other sites More sharing options...
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