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Fidd88

Frazer Nash FN5 gun-turrets

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Fidd old mate, this is very interesting, you mention the weight of this apparatus, do you have any idea of how much it will weigh during the pouring process? Also I sure would love to see a video of the pouring procedure........ this is quite new to me, and most interesting....

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Thanks, it's really great to get feedback and suggestions for my videos - I'm no David Lean! I'll try and film the pour, but its likely to be a slow process. Not sure when it will happen as my daughter possibly has Cv19, and we're therefore self-isolated, so rather than popping out to the shops to fetch plastic jugs etc, I have to order from Amazon. Grr! This is all first time stuff for me, so naturally I'm a bit more concerned about not ballsing it up, than I am about filming! I'll try. I need to do some calculations for the weight, but I've bought 20kg of the EP426 which will give me a finished cast of minimum 40mm thickness at the narrowest point.

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I took a few more pictures this evening having sorted the male-mould attachments. The little sticks on top are to tension the wires so that if can't move fore / aft or athwartships, they'll be tacked in-situ to hold them fast for the duration of the cure. I still need to cover the ABS male mould with mould-release spray before setting it up again for the pour. So you can now see how the whole edifice goes together. It's a bit "Heath Robinson", but should do the trick. There'll be an additional sandbag under the plaster-mould so that not all of the weight is being carried by the flanges of the mould. The current guestimate for the all-up weight when the resin is poured is 12kg, plus the weight of the mould which is about the same weight, so call it 25kg, or 50lbs if you will, and 12kg once demoulded.

mld1.jpg

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Thanks for the pics, I find this quite fascinating actually................  I do think however, you may need and small engine hoist to lift this, I am amazed at how heavy it will be..... engineering at a fine touch for sure.....  looking forward to more

Jeff

 

Hydraulic-Folding-Engine-Hoist-Shop-Crane-portable.jpg

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Cheers, I'm pleased you're getting something from it. Yesterday, I did the resin pour, which for various reasons was harder than I expected. Altogether far too many bubbles I think, which may prove disasterous when the casting is under vacuum or during the heat-treat. I didn't know at the time, but I wasn't at my best. By later afternoon I had a high temperature, and slept over 20 hours straight. Hey ho.

Latest film here:

FILM

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I've had a very difficult couple of days, demoulding the resin from the silicone and plaster mould, made all the more tricky by an error when applying the 2nd and 3rd coats of silicone. It took so long to demould, as I was very mindful that if I became impatient, it was going to be very easy indeed to damage the casting, as whilst the resin is very strong in compression, it's pretty weak in tension, and that any overly enthusiastic attempts to part one with t'other was going to result in a bust casting. Two days later, I'd got the bugger to separate cleanly. I learned lots throughout the whole process, and will be much better at it next time. The wooden box support worked really well in terms of minimising mess and keeping what would otherwise have been a very unwieldly mould under control.

FILM of demoulded tool and AAR

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I've been more or less stalled on this project, for want of materials and restrictions on movement due cv19, meaning that I can't get the vac-forming done. I did get a small tranche of final parts yesterday which have since been painted and fitted. These consisted of a pair of flanges to widen the apertures of each of the spent-cases chutes, and a reinforcing plate on the face of the chute as viewed by the gunner. In both cases these were to widen the apparent width of these chutes which although width'd from the best drawings I could find at the time, are rather too narrow. Also in this last load of parts were fittings which will be glued and screwed to the cupola structure, through which the Perspex window panels will be bolted. I've yet to fit these. Pics attached, the red arrows point to the new reinforcement plate with simulated rivets, and the two flanges per chute.

New Films covering this, and various other elements of the build in the usual place.

I hope you're all keeping well and out of the path of this bloody virus.

flanges3.jpg

flanges2.jpg

flanges1.jpg

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Posted (edited)

The vac-forming for the forward windows of the turrets has now been done, and some properly sized poly-carbonate 1mm sheet sourced for the side and overhead windows which are simple-curvatures. 

vac-forming film

Edit - Addendum: Pictures of front and front quarter panels, with as yet unpolished view through Perspex panels in 3rd shot. Very hard work on the fingers! By Sunday evening, gremlins permitting, I should have completed the front turret cupola completely, which will involve refitting all the brass strapping on the exterior of the turret, and then bolting these through the Perspex onto the fittings on the other side. Very tedious, but so far going fairly well.

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ftq1.jpg

Edited by Fidd88
addition of pics
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After a marathon effort today, the front turret cupola is finished, bar for the ventilators in the quarter right and left window panels, the position of which I need to research. In the cup2.jpg note the 3 M1 machine screws and nuts per attachment. Each nut was started with my cocktail-stick with a blob of blutak, and has to be placed on the thread end, then very gently teased with the stick until the nut starts on the thread, whereafter I can go on in with nut-spinner and jeweller's screw-driver to finish it. Once the cupola is complete, I'll put a little locktite on the exposed threads to prevent the nuts unwinding with vibration. Once the cupolas are completed I'll post some pictures with them on the turrets. The front of each cupola engages with "feet" on the turret assembly, and then is held down at the back by two screws which go down through the cupola and through the alloy plate on which most of the turret mechanism is built.

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Absolutely fantastic, my gob is well and truly smacked! If I didn't know I would think that was a restored full size cupola.

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Thats is just bloody amazin . . . . who would have thought it was for a flying model ??

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Well, to remains to be seen if it can. as there's plenty of potential "show-stoppers". The intention all along has to be produce a large model Wellington 1c, in Polish/RAF service, with interior cameras - some FPV - to take footage from within the model in flight - hence use of proper geodetics internally.

The second aim, is to build the model using alloy geodetics, as close as possible to those used on the original machine. Possible problems are radio-interference from the metal "basket" structure (it's basically a Faraday cage!) to expense and difficulty in construction, to metal-fatigue. Even if I can build it, it's hard to see the chance of multiple successful flights being higher than around 30%, and that may well be optimistic. On the other hand, it'll be deeply satisfying if it comes off. Some builders have made geodetics in wood, however these are usually limited to the upper-surface of wings and tail-plane, where it shews, but otherwise use bulkheads and stringers and longerons in balsa, ie not geodetics, for the fuselage. If mine works, it'll be the first metal Wellington, and the first all geodetic model throughout..

Today has been spent on the rear-turret cupola having finished the front turret cupola yesterday. I reckon another 3 days should see the rear turret cupola finished. I had some good news yesterday, the chap printing the front turret tub has despatched it, so once that arrives I'll be able to bring both turrets to completed status, and salt them away whilst moving on to the metalworking side of the project.

Attached are some pictures of the front turret cupola on the turret mechanism. Since these were taken I've added the rings on the ventilators.

if you're new to this thread, you may wish to check out my youtube channel which documents the build, and all the trials and tribulations of developing these prototypes - the intention being, eventually, to produce these as a "kit", if I can get the unit cost down. As currently designed, they're terribly time consuming to build, and very expensive.

r.jpg

fr.jpg

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Absolutely stunning, as an ex RC flyer and if I’d built something 1/16 as stunning as your turrets, they would never go aloft.....congrats 

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Cheers Phil. The hard work was really the CAD side of things. Not that I'd really want to do it all again but when it finally prangs - as all RC aircraft eventually do - I hope to have lots of film footage to remember it by! Having built the turrets, I now reckon I could rebuild them inside 6 months - as opposed to the best part of 5 years to go from initial drawings to where we are now..

Further to this, I've just posted a new film:

https://www.youtube.com/watch?v=ppVC-NaSqBM

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Bit of a red-letter day. Over the last day or two I've assembled the cupola for the rear-turret and married these to the internal mechanism. I decided to rework the clips which hold the perpex panels in place with the addition of 3d printed scale "penny washers", painted to a brass colour. These make putting the nuts on easier, as the screws can't fall out when trying to start the nut on the thread, and look much better from the inside. So when they've arrived and been painted, I need to refit most of the clips, this'll be much easier to do second time around with each window panel being registered by all but one machine screw - at a time.

Also still to come is the "tub" for the front turret, qv. I'm probably also going to make stands for them, similar to those used at the central-gunnery school, where gunner's under training could operate turrets powered hydraulically by a nearby lorry-borne generator. It'll be ages before I'm in a position to mount them in the fuselage. At some point I'll open the doors and try and photograph them from the view I hope to eventually obtain from the "gunner's eye" FPV cameras.

cups3.jpg

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cups1.jpg

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