Frazer Nash FN5 gun-turrets

[Jeff]

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....

[Fidd88]

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.

[Fidd88]

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.

[Jeff]

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

 

[Fidd88]

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

[Fidd88]

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

[Fidd88]

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.

[Fidd88]

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.

Edited May 15, 2020 by Fidd88
addition of pics

[Fidd88]

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.

[Wingco57]

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

[Fidd88]

Cheers! It also makes a rather fine hat! 

[FME erk]

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

[Fidd88]

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.

[Bomber_County]

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 

[Fidd88]

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

[Fidd88]

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.

[Fidd88]

Ever had one of those days? One where everything just goes completely pear-shaped? As of first thing this morning, I'd retrofitted both cupolas with the 3d printed scale "penny-washers" and only had the pair of small windows above the slots to glue into position. This all went beautifully, until I noticed a deeply unwelcome drop of superglue had somehow arrived in the middle of the front half-left window, the one with the cut-out for the ventilator. 

"Bugger"!  -  quoth I (with feeling)

I then mopped it off, and tried polishing it out with some acylic polish.

This extended the damage by spreading the interior of the turret with blue spots of polish and did nothing to the blob of glue.

"Bugger!.. with bells on"! 

At which sanity prevailed - not before time - and I walked away from all the tools and workshop lest any further cures of mine did yet more damage.

An hour later, after a consoling mug of tea, I returned, and decided to replace the quarter-panel, refitted the ventilator to it and cleaned-up the mess "the erks" had left, arriving back at the position I commenced at 8am this morning. Sad, but wiser.

Any further window-panel fixing will be done with my tried and trusted tiny-machine-screws, and if ever you see me reaching for bloody superglue, kindly whisper "remember the cupolas" to me, and I will cast it into outer-darkness with extreme prejudice.

Other than that, the last few days have gone well, with the front-turret tub painted and fitted, and the both cupolas complete (notwithstanding today's vandalism)

So, a couple of wiring faults to chase down, and then they'll be salted away for eventual fitting. One long-put-off bit of mathematics also occurred, with me working out the scale of the eventual model, after lots of close measurement.

I worked it out from the size of the turrets: 1:3.703, and via the ratio of the turrets to the length of a large scale plan from front to rear terminal rings, and thence to the known length of a full-size Wellington. Result 1:3.706! So that's comforting. The scale was 1:4.5 when I started the initial drawings for the turrets, but I changed the scale as I was concerned that at 1:4.5 there was virtually no clearance between the diameter of the chosen engine, and the cowl. At 1:3.7 I've a bit more wriggle room.

I hope your projects are proceeding well, and that none of you are using superglue!

 

[GusMac]

Glad you got it sorted. The 'big deep breath and walk away' is often best.

Look on the bright side you didn't glue yourself to it which is generally my default with superglue!

[Fidd88]

Thanks all, for the support and encouragement. As I've now completed the turrets, I've put a link to my final film on them in the "completed" section, but to save those following here from having to trawl over there, here's the link. All new footage and stills, and some narration.

Final film of the turrets  

[Edit] And a few pictures..

Edited June 6, 2020 by Fidd88
addition of pictures

[Fidd88]

This isn't strictly 'modelling' per se, but I've just finished lengthening the jig in which the fuselage, mainspar and wings will be built over the coming years. The change arose because I realised the planned engines would have been too tight a fit in the cowls, so the scale was expanded from 1:4.5 to 1:3.7 

This brings the fuselage length, without the turrets or supporting structure outboard of the two terminal rings to 5.02m, and a wingspan of over 7m. The increase in scale should also make rivetting and bolting the standard geodetic nodes (where they 'cross') easier as the channel will be larger.

Currently I have some pc woes, but once the new PC is up and running, I hope to start re-scaling and re-constructing the 3d shape of the geodetics around the fuselage, which will in turn provide the shapes of the formers used to bend each geodetic member. Happily these are symmetrical, so in effect I only need the ones for half the fuselage one side of the mid-line.

The next phase is to source and possibly adapt a pneumatic rivet-gun for miniature rivets. This has to be done to ensure that the final design of the cross-section of the geodetic channel can actually be rivetted together. The tooling cost for the extruded alloy being fairly expensive! So I have to get that one right 1st time.

Film of the jig (built 5 years ago, recently extended)

 

[Jeff]

Sir Barnes Wallace would be MORE than impressed, and I'm sure he is well smiling at this dedication to supreme detail............... this is incredible Fidd, old Mate.....

[Fidd88]

Cheers, I'll be happier once I've made some test-pieces of geodetics and dealt with several "problems":

1. Ensuring the tool-head of the rivet gun will fit in the geodetic channel to rivet the shear fittings.

2. Learned to control the curvature of the extruded channel without deforming the cross-section

3. Learned to accurately "notch" the geodetic channels where they cross - without causing crack-propagation and therefore metal-fatigue

4. Tested the proposed build technique and found it strong enough and sufficiently resistant to vibration/shock loads.

When that little lot is sorted, the build proper can begin, but it'll be an expensive experiment if it fails, the tooling costs for the extruded alloy is well over a thousand quid.  

All of these 4 are pretty nasty problems to solve. I think I've figured 2 and 3, in theory...

[Fidd88]

I've done a lot recently, but have absolutely nothing to show for it! The chief PITA has been my old pc becoming emphasemic, so that's being stripped and rebuilt as a standby pc for email etc, and I've spent a King's ransom on a new pc for CAD work, optimised for that and gameplay. What used to take 5 minutes to open on the old one now takes seconds. Loud cheers! What with copying multi-gigs of data from one to t'other and backing everything up, then dealing with a bad Microsoft patch (what a bloody shambolic out-fit they are!) I've now got all my beans in a row to crack on with the CAD work.

Also I've completed the jig and shot a few mins of footage of it in motion. (below)

A few months CAD work ahead now.

 

[Fidd88]

Hi all,

Sorry there's not much to look at just now, but I've been having a huge clear-up/reorganisation in the workshop, which created a lot of additional stuff to do indoors. The CNC router, it's table, and the large enclosure which goes around it, are all slated to come up into an unused bedroom, and the liberated space will partially be used to relocate the 5 boxes of mini-draws used for storing all the machine-screws and what-not. Where they are currently I have to reach over the jig to get to them, which is far from ideal.

However, "it's all grist to the mill", and should result in an easier time of it when bending the extruded channel eventually commences. I'll also be lofting a whole bunch of materials, moulds and so on used in the production of the turrets, which should liberate a lot of shelf-space too.

In the meantime, I'm now learning to fly RC aircraft, practising on "Realflight9", It's just as well I did, as I crashed innumerable models before getting the hang of it! One of the things to adjust to is the rapidity with which a circuit is flown with an RC aircraft relative to a real one, so flying a complex aircraft with undercart and flaps has one working like the proverbial "one-armed paper-hanger"! I'm doing about 20 circuits a day now, in various wind conditions, and am looking to improve the consistancy and accuracy of the circuits flown.

I'll post again when there's something tangible to look at!

Cheers, 

[Bomber_County]

Having flown RC by all means use the PC version but I recommend the real thing as well. Find a club and become certified, every club have training sessions with buddy box controls, so if you get into difficulties they can help you out. You can buy an ARTF (almost ready to fly) cheaply, then add a transmitter.........