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Thread: May be of interest to some - model FN5 turrets at 1:3.7 scale

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    Default May be of interest to some - model FN5 turrets at 1:3.7 scale

    Hi all,

    The cognicenti amongst you will spot the odd error, some were too expensive to correct (the turret doors) and others too much work to fix (the central console height and the lower mounts of the "rams") but I've spent the last 5 years building a pair of model FN5's, the intention being to film from within these turrets, with them fitted to a model Mk 1C "Wimpy". There's quite a few films on my youtube channel documenting the "triumphs and disasters" of the build. There are, as far as I know, no technical drawings of FN5's in existance, so I'm greatly indebted to Mark Evans who had measured wreckage of turrets and drawn them in CAD, which gave me a really useful start to the project.

    The turrets are built largely from 3d printed nylon, with some printed abs, sheet aliuminium and brass, and are largely held together without glue. Instead I drilled and hand-tapped holes for M1 and M1.6 machine-screws, and screwed or bolted all the parts together. This had the huge benefit of being able to disassemble a turret and try a different build sequence, which happened several times over the build, usually because of difficulty getting tools into tight gaps.

    The turrets feature working elevation of the gun-cradle, via pneumatic rams shrouded to resemble the hydraulic ones fitted during the war. The sight-bar linkage all functions keeping the gun-sight parallel to the guns. The sight itself is a working collimating gunsight, and has an area in plan of about an average thumbnail. This was designed and built in collaboration with Tim Noack.

    Having just completed the turrets, I've made a short 15 minute film, with a lot of footage and stills taken from within the turrets, and some narration.

    You can use the link below, but if you wish to see them full-screen, simply search youtube for "Fidd88" and follow your nose.



    There's also many many stills on Flickr at:

    https://www.flickr.com/photos/188620249@N06

    If you'd like to comment, or advise of errors you can see, YouTube comments would be appreciated - or here if you prefer

    Cheers, Tim Huff
    Last edited by 1bfts25course; 6th June 2020 at 01:32.

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  3. #2
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    Default Re: May be of interest to some - model FN5 turrets at 1:3.7 scale

    That's amazing work, Tim. I learned a lot about turrets just by watching the video.

    All the best with the rest of your project.

    Robert

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    Default Re: May be of interest to some - model FN5 turrets at 1:3.7 scale

    Hi Tim,
    That's outstanding, really impressive.
    Like Robert, I have learned a lot about the turret through your video.
    Good luck with your future plans for them.
    Gerry

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    Default Re: May be of interest to some - model FN5 turrets at 1:3.7 scale

    Cheers lads, it's really great to get some positive feed-back on these after nearly 5 years slog in the workshop manipulating thousands of tiny machine-screws into position with a nothing more than a cocktail-stick with a ball of "Blutak" on the end of it! (Most useful tool on the workshop!). Once the nut or screw is "started" by carefully "tickling" it with the Blutak, I then go over to a regular nut-spinner or jewellers screw-driver. A lot of holding my breath too! The hours spent most evenings on CAD were also a bit of a grind, especially when things went wrong.

    The next phase is to get all my beans in a row to fabricate the fuselage from extruded alloy geodetic channel. On the real aircraft the strip alloy was fed into a very clever machine that progressively curved and folded the alloy to the required cross-section. I can't devise that - it's too complex for my abilities - so the intention is to devise a system to curve the extruded channel with a chain of inserts inside the channel to prevent deformation of the cross-section. So for the next year or two I'll be sorting those issues out and then building some test pieces for destructive testing with the LMA before moving onto producing all the patterns which define the curvatures of individual members around the fuselage at 45 degrees to the horizontal datum. If I can solve all the issues, I'm anticipating the fuselage build to occur fairly quickly. It's the preparation that takes time. The wings and nacelles are rather more complicated to make, and will take much longer.

    I attach a picture of the old-scale (1:4.5) geodetics and node fittings (as redesigned by me) which shews the general principle of the structure. 99% of all joints on the aircraft are one of the two types in the picture, so once they're mastered I'm 'away to the races' as it were.

    1 of 300+ stills on Flickr

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    Default Re: May be of interest to some - model FN5 turrets at 1:3.7 scale

    I've also uploaded a new video of the jig I built 5 years ago in preparation for the 1:4.5 scale model. The scale was changed owing to the very tight fit of the planned engines, a pair of 9 cylinder radials from Air-En in the cowls. Consequently the jig had to be lengthened by 30cm, which will bring the total length of the fuselage to 16 and a half feet, between the terminal rings in the geodetic structure behind and in front of the front and rear turrets respectively. The wing-span will come out at 23 feet, when assembled, the wings outboard of the nacelles being removable for trailered transport. Similarly the turrets, and suporting structure will be assembled onto the model at the field.

    There are some other advantages to the new scale, the alloy geodetic channel, which will be extruded as straight sections, then curved to shape, will be a little larger in cross-section than previously, which will make it a little easier to get the rivet-gun in where it's needed.

    The next task will be to look into the rivet-gun tool size, ensuring it will fit into the channel during assembly of the standard geodetic nodes, before finalising the design of the channel, and the internal fittings.

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