Frazer Nash FN5 gun-turrets

[Fidd88]

Hi all, 

As it's a bit of an unusual modelling subject, I thought some might be interested in the pair of FN5's I'm building for a very large RC Wellington Mk 1c, in the colours (eventually) of one of the Polish RAF squadrons operating the type in 1941. The turrets will have "FPV" cameras installed eventually, allowing the rear turret to track targets through a working reflector gunsight (built in collaboration with Tim Noack) whilst the front turret will have a more general view that is pan/tiltable independent of the turret movement.

The turrets feature working pneumatic rams elevating and depressing the gun cradle, with all the mechanical linkages that keep the gun-sight parallel to the guns working as per the full-size turret. Virtually no glue has been used anywhere, with most parts 3d printed in SLS Nylon, then holes drilled and tapped before finally being screwed together, usually with M1 machine-screws, nuts and washers.

The turret have extensive lighting, an overhead lamp, spot-lamp, amber warning light, and 3 coloured Bendix lamps, all of which are either "grain or rice" or "grain of wheat" light-bulbs. The gun-sight has an LED, and produces an auto-dimming  glowing reticule in correct for the era, which at the correct focal length us the correct size. All function.

From initial research to where the builds are now has taken three and a half years during which I've taught myself CAD, soldering, and using an airbrush, as well as all the engineering side to have the moving parts, often separated by gaps of only 0.1mm, work as intended.

If you search youtube for Fidd88 you can see the videos that documented the build over the last 13 months or so. I should point out that I'd never used a cine camera or looked at youtube when I started, so some of them are a bit dull and repetitive, I'm not what you'd call a "talented film-maker"!

I'd recommend starting with the most recent films and working back.

All of the parts have been 3d printed from my own CAD drawings. There are a few known errors in dimensions, but as there are no extant technical drawings to work from the whole thing has been reverse-engineered from photographs. No two museum turrets being the same, this was a difficult exercise as you may imagine! It's as accurate as I could make it however.

Anyway, here are a few pictures. If any of you have comments or questions, please feel free to ask, and I'll do my best to explain.

There's still a lot to do: 

Fabrication of initial plug to make mould to cast positive over-which hot Perspex is pulled to make cupola windows.

Bolting window panels to sub-frame, attachment of cupola

Plumbing of pneumatics to drive elevation and depression of gun-cradles

Camouflage of same to resemble hydraulic pipes

Addition of plethora of cosmetic hydraulic pipework

Weathering, dirtying and so on of entire turret paintwork.

When all services are proved, lock-tighting of all nuts.

I hope you find this interesting, if not up the amazing standards of modelling here! The eventual intention is to build the Wellington 1c in extruded alloy channel to form a geodetic construction as per the original aircraft.

[Clunkmeister]

WOW!  1/3 scale?  That looks phenomenal so far. 

That’s definitely Large Scale. 

[Fidd88]

It's approximately 1:4.5 scale. The scale being determined by two things, the relatively small choice of 9 cylinder radials available to power it, and how small one can make the internal fittings of the geodetics which enable two geodetic members to cross each other but remain locked in relation to each other. 

Incidentally, I love your Rescue Lance!

I attach a few more pictures of the mechanism within the turrets, and one of a similar actual one in the mid-war onwards all black scheme. likewise the 2nd shot of the extinguisher is for comparison. I had a lot of fun making my own transfers (decals).

[Jeff]

WOW! This is fantastic..................incredible workmanship and attention to the finest of details................... HOLY

[FME erk]

Am I allowed to say "Bloody 'ell"  thats brilliant.

I can't understand why you didnt go for it and build a full size one  . . . .

The detail you have put in there is superb and a credit to your skills and I for one will look forward to you posting more.

I going to youtube now to look at what other parts of the aircraft you have achieved results with . . .   

Carry on the good work

David

[Bomber_County]

What David said, some very fine modelling skills on show. Welcome to the forum, it’s the friendly corner of the web......

[Fidd88]

Thanks for the welcome chaps. Really the whole turret thing has been dictated by what I could actually draw in CAD using Autodesk Fusion 360, and what details would resolve in SLS nylon. So for example it took me over 60 attempts to correctly draw the curved and twisted ammunition feeds (I was bloody well "curved and twisted" by the time I achieved them!) The green metal pieces that connect the arch of the turret are known as chordal brace stiffeners, and I drew them over 40 times, from scratch. So it's really more being stubborn and always seeking to improve the drawings than actual model-building talent. That's my tuppence worth!

Research was also a problem, as as far I can tell, there are no extant technical drawings, and the illustrations about are generally wrong in places. Hence the over 1200 revisions to the main assembly drawing, and around the same number of individual component drawings.

Currently there is no aircraft model to attach them to, although I have built a home-made jig on which the fuselage, inner and outer wings, floating main-spar, tail and fin can be assembled. The finished aircraft will be just over 4.5m long including the turrets iirc.

Attached are pictures of the jig (yellow) shewing the central black bar on the aircraft datum, and the "cage" which rotates and can be locked off though 360 degrees of rotation  at 16 degree intervals iirc. The idea here was to make assembling the port or starboard side as easy as the other, without having to drag the whole thing out of what us a very small workshop! There's also an (old) picture of the two main join types in the Wellington's geodetics, which have had to change slightly to ward off metal-fatigue issues with the reduction in scale. Also pictured are the individual .303 rounds of my own design, which fitted together into a tapered slot of the adjoining round. This enabled "belts" to be formed, which would curve and twist evenly around the chutes, before being glued in situ. It was that or to try and construct  a curved and twisted belt in CAD! No THANKYOU! (with feeling)

The final picture is a method of making geodetic channels out of carbon-fibre, using extruded silicone moulds, the idea being to place these over a former to go hard in situ before being demoulded. Amazingly it did work, with weight of 33mm to the gramme and was very strong to shear-loads, but rather less so to tortional ones. The failure rate and time and money involved really put the tin-lid on it, although I may use it for short and highly curved ones.

At the moment I'm fighting with the clips which go on the back of the brass strips, sandwiching the windows, and recommissioning the CNC router to make the plug for said windows. Both are a little frustrating just now!

I daresay you have people here who can draw up parts, for 3d printing, but please sing-out if I can be of help in that regard.

[JeroenPeters]

Mind. Blown.

[crazypoet]

This is surreal...  My mind is - yet again - completely twisted ‘round itself trying to comprehend the talent, skill and pure stubbornness (as it takes to make things perfectly believable up-close) that I see on display here

and did I read that you’re going to fly this thing on scale radial engines?!?!?!  With functioning turrets and gunsights???

gawds - I hope to live long enough to master even 1/10th the skills I see on display here every day

[BlrwestSiR]

Still trying to find my jaw after it dropped and hit the ground somewhere.

Truly amazing work there. Can't believe just how big it is.

Carl

[Fidd88]

Hehe. the funny thing is I havn't actually added many of the detail parts yet, mainly as their too fragile to stand all the wrangling that's done fitting other more hefty parts. There's a huge amount of hydraulic pipes, hoses, brackets and general plumbing to add shortly. American turrets were developed from British examples sent over in 1941 by Boulton Paul and Frazer-Nash, and subsequent American refinements were either all electric or electro-hydraulic as per Boulton Paul designs, whereby all the hydraulics were in the turret, which made for less leak-prone designs. This being a Frazer-Nash turret, there's pipes bleedin' everywhere!

I'll take some more up to date shots tomorrow and post back.

Thanks lads,

[Fidd88]

As many of the previous pictures posted are several months, or in some cases years old, I took the camera into the workshop and 'shot some more stills' (I typed more carefully this time)

Apologies if one or two are a bit similar, I can't view pictures already posted when in the workshop easily. I've made the max dimension 2000 pixels, I hope this isn't too large for here?

My little you-tube channel documenting the turret builds is here: Fidd88 

I expect that's about it for the foreseeable until the windows are done, or the pneumatic system is up and running. Happy to answer any questions people might have regarding the limits of SLS nylon printing, or on the subject of gun-turrets. If I can help with CAD drawings for your own projects, anyone, please just ask.

In the picture below, the battens on the roof are my patent storage. The natural wooden battens are screwed to joists at every joist. The red ones only span 1 pair of joist each, and have a screw only on one allowing them pivot parallel to the joist for getting long objects up there. Home-made fittings with a detent position prevent them moving and dropping stuff on my nut!

[Wingco57]

Absolutely bl@@dy fantastic. Just a thing for the man cave. Although I have never seen that type of fire-extinguisher in any

British power turret.

Well done.

Cheers

Cees

[Fidd88]

It's modeller's license on my part, possibly. I deduced that there would likely be one on inside the front turret, as the gunner couldn't escape from there without help from other aircrew, (in the air) and this took time. The rear turret, I learned after fitting it, had an extinguishers stowed on the fuselage wall immediately forward  of the turret, so that one is definitely wrong. Similarly the position of the thermos-flask holder was a case of putting it where it might plausibly have been fitted. No examples survive in museums, although there are usually a raft of empty holes from which now missing fittings were once fitted. I have read that some 15 wire mesh thermos-holders were scattered throughout the Wellington, so I believe it's reasonable to assume provision was made in the turrets. I've read accounts of front-gunner drinking tea from thermos within the turret, but as to where precisely it was stored... I know not! Frankly there's buggerall room, so not that many spaces the extinguisher and thermos can fit and still have the gunner get to the controls/tanks etc.

As for the extinguisher type, this I believe to be correct, although the brass-finish may have been over-painted in a duller colour. If it was, I have no scheme to work from.

Something I forgot to mention about the "jig" is the function of the "cage", which is the 4 long yellow bars at the corners of the rectangular end plates (yellow). What you may not be able to see in shot is that all these cage bars have very accurately positioned metal measuring tape JB Welded to them, reading from a common datum. There's also a trolley with register marks, which can be positioned along the uppermost cage bars, on either the long or short lateral axis, to the mm. On the trolley is a laterally sliding bar, capable of being locked about 20 cm either side of the central position, and from the trolley descends a plumb-line on the same centre register lateral line. This enables me to very accurately measure linear distance anywhere on the fuselage, regardless of the jig rotation. Vertical height can also be measured, however corrections need to be applied owing to about 3/4" "sag" of the cage-bars over their length with a further correction being applied for the rotational angle of the jig. The central datum bar, to which all temporary structures defining the shape of the fuselage are bolted is 50mm square section, with radiused corners and 4mm thickness. So that doesn't perceptibly sag! (It is however bloody heavy)

[crazypoet]

I am truly jealous of your workshop!!!

my entire bench is shoehorned into one small section of my living room... but I can dream!

[FME erk]

Thats not modelling its engineering. Fantastic stuff at that 

If the turret will be able to rotate and guns elevate etc I presume this will be done by remote control once the aircraft is built and flying ??

Will you be sourcing aircrew members or will it be possible to 3D print the basic torso and dress them accordingly ?

I am just thinking ahead of some of the things you are going to need, tyres, propellers, etc which, as a radio control aircraft builder, you have already eyeballed fromthat field.

Mr Jackson may have a need for such a Wellington in his up coming (?) remake of a certain film.

[IainMackayDall]

Just for context. Here is a Fraser Nash. My Father was an Lt Royal Navy Engineer. It seems just after D-Day, on his American build LST on Gold or Juno, or maybe later from the Mulberry harbour. He managed to find a BMW marine engine to bring back on said LST. Somehow for some reason he replaced the engine in his Fraser Nash with this Marine BMW ( I presume it must have been bigger and more powerful ) But it never quite worked out as planned, It worked but constantly overheated on long trips. Maybe the engine missed all that cooling seawater?

[Fidd88]

P'raps I should contact Mr Jackson at that, as the FN5a in the front Lancaster turret is essentially a truncated version of the FN5 with a slightly different cupola and doors... Nice pic of the FN car btw. 

Hi all,

 

I wasn't expecting to upload a new film quite so soon but last night I connected up all the pneumatic lines to the distribution box and thence to the rams, A pair of syringes on the supply lines stand in for the yet-to-be-devised servo operated "fine tracking valve" and the "speed-limited" supply from the compressed air tank.

 

It all worked first time, which was a great surprise and most welcome.

 

Footage of the working rams and sight bar mechanism seemingly moved by "magic":

Film of mechanism moving via pneumatics

[Fidd88]

To answer some of the questions above:

FME Erk, you're quite correct, my "modelling" skills, in terms of painting, weathering and so on are still fairly poor, I only recently re-learned using an airbrush after a 30 year hiatus, and am still not very competent with it. It's actually the reason I found this place, to learn more.

The eventual intention is to have gunner figures within, arranged so that the FPV cameras are largely, or totally concealed within the figures when it's a static model on the flight-line, but these will "open up" in such a way to allow unimpeded filming from the cameras when recording. The front turret gunner's figurine will likely be filled with lead-shot to assist with correcting the centre of gravity, whilst the rear gunner will be hollow and as light-weight as possible. That's a long long way away though, as the FPV cameras will be the very last job on the build. Other FPV cameras will be on the pilots seat and likely another at the rear end of the raised floor above the bomb-bay, able to pan and travel along rails towards the pilots position past the navigator and wireless op crew positions. That's the plan. However there are literally decades of work ahead to build the geodetics and solve all the issues which will doubtless arise in doing so.

Crazypoet, this is actually the 5th workshop I've built now, so it more or less does itself. I always have pegboard on most of the walls on one side, with vertical shelf rails between the pegboards. This gives great flexibility, as I can use the pegboard to put hooks or other fittings to hold tools, but if needbe can use that same space as regular shelf-space. So as requirements change it's easy to change the type of storage used. All walls and ceiling are painted white, with lots of light-fittings to reduce shadows being created, and  powerful spot-lamp provides directable light near the bench. The floor is painted green to aid finding dropped parts. An M1 nut is about the size of this "O"! Lots of power-points finish the job.

I have a couple of "rules" which help keep things organised:

• Virtually nothing is stored on the floor to aid keeping it clean and clear, and to mitigate fire-risks and tripping on stuff
• Shelving either starts deep at floor level reducing with height (for heavy bulky items) or vice versa for light bulky storage.
• Maximum use is made of every nook and cranny to store smaller items, see above door and ceiling.

This works for me - YMMV of course, but you don't need much room to get an effective workshop up and running, but it does need designing rather than being allowed to grow organically if you see what I mean...

[crazypoet]

2 hours ago, Fidd88 said:

This works for me - YMMV of course, but you don't need much room to get an effective workshop up and running, but it does need designing rather than being allowed to grow organically if you see what I mean...

Exactly right!

i’m finding Ways to work with larger projects in limited space - i’ll Need room for that 1/48 B-52 at some point - so planning and best-use-of-space 

[Ryan]

Why dont you take a break and make some turrets for the 32nd B-24?

Fabulous work sir.

Ryan

 

[Fidd88]

On ‎9‎/‎11‎/‎2019 at 7:12 PM, Ryan said:

Why dont you take a break and make some turrets for the 32nd B-24?

Fabulous work sir.

Ryan

 

hehe. I guess that's 1:32 scale? There's no way in Hades I could engineer and build a "working turret" in that scale, not one with motorised moving parts. I might manage down to about to 1:8 but that would be a real struggle. At 1:4,5 is a good scale to work in given the structures, material properties and so forth. The work In one of these is fairly significant, most evenings and weekends for 3 and half years at the drawing board (CAD) and researching, with continuous revisions.

I am considering specialising in modelling turrets but the scale will likely be fixed at circa 1:4.5 and hideously expensive, as they take years and months to build, rather than weeks, especially for the first example of a design.

Thanks for the praise, it's nice to bring it out into the light after a prolonged build

EDIT: Helimadken did produce working FN5a and FN20 turrets for his 1/10th scale Lancaster, which can be seen below, but it's a very different construction technique to mine. Very impressive though, I think you'll agree!

 

Edited September 13, 2019 by Fidd88
Addition of 10th scale FN5a turret video

[Fidd88]

2 hours ago, crazypoet said:

Exactly right!

i’m finding Ways to work with larger projects in limited space - i’ll Need room for that 1/48 B-52 at some point - so planning and best-use-of-space 

Blimey O'Reilly! That's nearly a 4 foot wingspan? One of my earliest memories is seeing those on the news bombing the crap out of the Ho Chi Minh trail, which looked very impressive to my four year old self. I resolved, then and there, never to go to war with America! 

[crazypoet]

1 hour ago, Fidd88 said:

Blimey O'Reilly! That's nearly a 4 foot wingspan? One of my earliest memories is seeing those on the news bombing the crap out of the Ho Chi Minh trail, which looked very impressive to my four year old self. I resolved, then and there, never to go to war with America! 

This from the man who’s building a 4.5 **meter** RC Wellie???   

But yeah, I guess we both have a certain soft spot for the big’uns!

I very much look forward to following this build over whatever number of weeks or years it takes to complete 

[Fidd88]

Did you ever see James May's "toy stories" series (I think it was called) where he and volunteers built a life-size Spitfire plastic kit?

 

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