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Scratch Build Partial Strip Down Vickers FB 5 Gunbus


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Evening All,

 

I have been back to soldering again because I needed to attach the lower wing spars to the fuselage nacelle frame. The wing spars are brass bar and the wings have a small amount of dihedral, so I had to bend the bar to get the correct angle. This was done by placing a bar on the front elevation of the plans, marking the inflection points of the dihedral and gently bending the bar with a pair of pliers. Having made one spar the second had to be made to exactly the same shape. Having achieved this I now had to solder the spars to the frame, a task which I had been putting off for some time, (which is one reason why I started on the top wing as described in the last post. Anything but solder the lower spars...). This is a pusher biplane which will be all struts, booms and wires when it is completed, and if anything is out of true it will show up like a sore thumb, so getting the spars dead square and at the correct angle of dihedral on each side of the nacelle is absolutely essential if the completed model is to look right. During the soldering process everything has to be rigid to prevent movement, but setting up a jig to hold things steady on a kitchen worktop is not easy. I am not one for fancy, (and sometimes expensive), jigs and tools - everything I do is a tribute to Heath-Robinson - and I firmly believe that much can be achieved with little. Except patience - you need a large amount of that when scratch-building.

 

So I set up my jig as follows:

 

44807276301_7c1525858f_c.jpg

 

This is jig 1: it was designed to align the spars correctly on the base of the nacelle frame. The spars had been coated with solder paste to encourage them to stay in place long enough for me to be able to heat the joints with the tip of the soldering iron and make a stable, (but weak) joint. Now I could turn the assembly over and pin it to a block of balsa, (jig 2), so that it would not move while I really made a permanent joint with silver solder. This also shows how I added the frames between the spars - the left one is being held rigid and in place with pins:

 

29870515977_1dc1e47b90_c.jpg

 

Repeat the above on the other spar, clean up the joints with a file and I had this:

 

44807276391_294dd28625_c.jpg

 

Or from another angle:

 

44807276421_56ba431649_c.jpg

 

I  added the frames between the spars at the bottom of the nacelle after the spars had been soldered in place. It did mean that I had to solder one joint three times because it came apart twice, but I got there eventually. The short white pieces on the top of the nacelle are plastic rod held in place with CA because these are too small to make from brass and solder into position. The nacelle and lower spar assembly is not quite complete - there are some pieces to be added to the nose but they will wait until later otherwise they will be in the way and get damaged easily. (Guess how I know?) I was delighted to find that when I checked this assembly against the plans everything lines up as it should - including the dihedral on the spars. I also tried out adding the ribs to the spars just to get a sneak preview of what they will look like on the completed model:

 

29870515957_b27f77518a_c.jpg

 

This model is turning into a "how-to-learn-from-mistakes" exercise. I realised that having made the ribs for the exposed wing sections, I would have to make some more because a number of ribs have three slots between the spars, and I had only made ribs with two! So back to the plastic strip and more filing, drilling and cutting....... However clouds have silver linings - well sometimes - in fairy tales and other works of fiction, don't they? In my case it was not fiction, it has really happened! I was soakling in my bath wondering how to extract the brass rods from the upper wing described in the last post when I thought that I would have one last check of the alignments of both sets of spars, including  those on the fuselage frame. When I checked the top wing spars with the lower pair, I found that they align exactly!! The spars in the upper wing had not moved as I had thought, and my improvised jig for holding them in place while the epoxy resin cured had worked. Joy of joys!! This was the kind of "mistake" that I would like to repeat. Please do not ask how I came to believe that there was somthing wrong because I just do not know. But having discovered that I could use the wing assembly I proceeded to add ribs using 10 x 30 thou Evergreen strip and putting Mr Surfacer 500 and 1000 filler along the edges and sanding it all down. I also cut out the aileron and treated that in the same way. The happy result for me is that I have half of the top wing complete except for drilling the various holes for struts, rigging wires, pulleys, aileron hinges, etc which will adorn it when finished. I have started to work out how to represent the internal bracing wires which will extend from the centre of the wing to the uncovered section - more on that later.

 

29870516067_27b8d09820_c.jpg

 

On the other hand I have found that the nacelle half that I have moulded is not quite the right shape, so I am going to have to modify the male mould and make a new half. Another error! I have also got to think about how to finish the details of the cockpit and add them to the nacelle.

 

Thanks for looking.

 

P

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  • 4 weeks later...

Evening All,

 

This is a slow build, not assisted by many interruptions from life.... My thanks to Bigbadbadge, Steve and Ian for you positive comments. I am sorry not to have replied earlier, but I was distracted by both trying to get on with the model and the aforementioned interruptions. I have also been experimenting, with some success, and have therefore been waiting to be able to present something of interest to readers. I hope that what follows will not disappoint.

 

First, as noted in the previous post, this is a model with a steep learning curve, so I will get the mistakes out of the way. I had been a bit concerned about the wing which I reported on in the last post, and decided that I would reject it after all as the curvature on the underside was not sufficient, and the tip was flat rather than curved. I had still to mould the lower wing so I decided to have another go at moulding a new set of wing sections for both the upper and lower wings. When I tried to do this before I found that I could not get a clean pair of mouldings, and I was going to try to use a vacform machine to make some new ones. However after giving the problem some thought, (my brain can accomplish such feats when I am not being distracted by other things....), I decided that I would have another try using my Kitchen Method (ie my gas-grill), on the grounds that a vacform machine is too sophisticated for the average modeller, i.e. me. I considered that the cause of the problem was that as these are relatively large mouldings, (they are the largest that I have attempted to date), I was not heating the plastic sheet and former enough, and the male mould was also not hot enough. In particular the male mould was probably cooling the plastic sheet sufficiently to prevent it from bending easily. Consequently I placed the male mould face up on the floor of the grill so that it was warming while I heated the plastic sheet. This I heated by holding the former at twice the normal distance from the gas flame i.e. approx 4inches (10cm) with the plastic facing away from the flame. This meant that the plastic did not curl and bubble while the wood former absorbed much more heat. Heating took two minutes and when I withdrew the former and mould to make the pressing I managed to get a good set of mouldings almost first time every time: actually I had to make 6 attempts to get 4 usable parts. Before I had made 10 attempts to get only 4 usable parts. I will describe in the next post the manufacture of the new wing halves as I am currently in the process of making them.

 

I also needed a new nacelle half as also explained in the last post, so I modified the existing male mould and made a new nacelle half at the same time as the wing sections. The cockpit openings and various holes for spars, struts, oil tank, rudder bar, etc were drilled or cut out and the new part painted. Before this I had been experimenting with the idea of using real metal for the upper decking and underside of the nacelle. Vickers Gunbus nacelles consisted of a steel tube frame covered with aluminium on the top, bottom and nose, and fabric sides, so I cut the ends off an old beer can and the split it down the middle:

 

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Suitably sized and shaped pieces were cut from the can after the printed logos had been removed,

 

44498527315_764467f93a_k.jpg

 

and I then tried to attach these to the old nacelle half which I was discarding because it was the wrong size and shape. It was at this point that I found that my good idea was not so good after all. I could not shape the pieces around the nose without causing creases in the metal. In addition the junction between the edges of the metal and the plastic which represents the fabric sides was much too proud. Finally the pieces around the nose also had horribly large and out-of-scale joints and I could not think of a way of making these less prominent. End of another good idea!

 

Many of the interior details of the nacelle had to be fitted before I could put on the nacelle side, so I added the fuel tank behind, and instrument panel in front of, the pilot, and the starboard wood side panel as this will be set against the solid nacelle half. This panel has the oil pulsometers (pumps), which were an aftermarket part from Taurus Models. They are very small but very finely detailed and I am glad that I have not had to try to make them from scratch.

 

44689808234_ae95b4073f_k.jpg

 

These were fixed to the panel before I attached the latter to the fuselage frame, and then I added two lengths of wire painted a copper colour from the pulsometers to the sides of the fuel tank where they disappear. In reality these would have been connected to the oil tank and then the inlet to the engine crankcase, but I cannot find any drawings or photos of this section of the aircraft, and anyway they would probably not be visible after the nacelle side is in place, so I am not bothering. I did add a fuel line which runs from the hand pump on the port side of the nacelle frame via the front of the instrument panel and behind the starboard side panel, over the top of the fuel tank to the engine - this would be seen when the nacelle half is in place. There is also a frame member behind the fuel tank - I think that it supports the end of the engine crankshaft:

 

44688927974_d53d93818f_k.jpg

 

Next part was the new nacelle half. I decided that although I could not use metal I would represent the stitching between the metal and fabric parts with real thread, so I drilled two lines of holes, starting at the top rear:

 

43596523040_4c9daa33cd_k.jpg

 

and working my way round the whole unit. After three laborious sessions I had this:

 

43596522910_fd78624402_k.jpg

 

and before anyone comments that the holes are not exactly the same distance apart and in dead straight lines, I can assure you that they were not so on the actual machines either, as photos show! I also drilled the holes for the rigging which will be attached to the fuselage frame later. Then the sewing began.... and after two more laborious sessions I had this:

 

43596523050_6f20f683ef_k.jpg

 

But as the old proverb says: "patience is a virtue....." and if you have enough of it, and the time, you will get this:

 

43596523060_b8fc127409_k.jpg

 

The nacelle half has been permanently attached to the frame. Now I could add the observers seat in the front:

 

43596523000_d784cd183d_k.jpg

 

and the engine firewall to the rear:

 

45361884592_fe373a518b_k.jpg

 

Well if you have got this far, thanks for looking.

 

P

 

 

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Dear Phoenix

Have you thought of using tissue paper and cellulose dope to make the flying surfaces of the wings? You already have the ribs. This was something my dad taught me about 50 years ago with flying balsa wood gliders that use tissue paper to cover  the wings.

 

Regards Toby

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26 minutes ago, Sofusthecat said:

tissue paper and cellulose dope

Ah yes...my favourite was the Guiilow's Nieuport 11.  It was good flyer on calm days.  Don't forget the final stage of that process Toby: a light mist of water from plant sprayer and left to dry will tighten up the paper over the ribs.

 

I might have to build one of those this winter.  It's been a donkey's age!

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5 hours ago, Sofusthecat said:

Dear Phoenix

Have you thought of using tissue paper and cellulose dope to make the flying surfaces of the wings? You already have the ribs. This was something my dad taught me about 50 years ago with flying balsa wood gliders that use tissue paper to cover  the wings.

 

Regards Toby

Thanks for the idea Toby but I fully intend to have one half of the model covered as per a flying machine, and the other side uncovered to show the internal details and structures which are not normally visible. I know that this is not an original idea, (a modeller did something similar in 1/72 scale with a Moraine Parasol on ti site some years ago), but I wanted a challenge that is a little different from just building a straight replica. This means that I will have to construct all of the internal wing structure and rigging.... Er yes, I di write that, but please do not ask me how I am going to do that yet because I have not worked it out yet. As usual with scratch building, I am writing re-writing the instructions as I go along....!

 

P

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  • 2 weeks later...
On 10/21/2018 at 7:54 PM, TheBaron said:

Words fail me.

This is simply magnificent in all respects P. 

Whether soldered or sewn, the work here absolutely inspires me!

Thank you Tom: from one who does not hesitate to plunge into some of the more difficult or arcane aspects of modelling media and techniques, I take your comments as the highest compliments. I am simply trying to follow where others have already led.... and nearly falling off the learning curve in the process!!

 

P

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Evening All,

 

I have been able to spend a little more time on this project lately and am able to report some new developments with specific reference to the wings. The model will have one half "solid" i.e. it will look just like a normal aeroplane with the external surfaces and colours, but the other half will be exposed to show all of the structural elements - that is why I have only moulded one half of the nacelle covering. The starboard (right) wing wings will be "solid" and it is these that I have been steadily working on recently, but I have also carried out an experiment for proof of concept for the port (left) wing halves.

 

I started by moulding the solid parts of the wings as upper and lower surfaces - I have described the procedure already. For the lower wing I had to put a rib in at the fuselage end as there was a small gap between the nacelle side and end of the wing. The rib was made from 15 thou card and two holes drilled and squared off to allow the spars to pass through. I also butressed the rib with some scrap card:

 

DSCF9529.jpg

 

Blocks of scrap plastic were glued to the lower wing shell to provide support for the brass bar spars and to ensure that where I will have to drill rigging holes later, there will be continuous plastic otherwise the rigging thread is likely to disapper into the cavity and I will not be able to pull it tight:

 

DSCF9531.jpg

 

To protect the nacelle I wrapped it in a plastic bag which had been slipped over the brass bars: that was to stop me from accidentally damaging the nacelle and attached rigging wires, and stop dust and other muck getting into the cockpit areas where it would be difficult to remove later. I cut a small strip of plastic to fit into the wing tips: experience with the top wing had shown me that a gap is likely to appear there when I shape this area and I wanted to ensure that there is enough plastic to allow for much filing and sanding. The spars were epoxied to the wing:

 

DSCF9533.jpg

 

and the top half of the shell glued into place. The structure was held with hair clips while the resin cured and glue dried out:

 

DSCF9534.jpg

 

Much scraping, filing and sanding followed to get the tips to the correct shape and shape the leading edge and thin down the trailing edge. Some filler was needed to sort out some unwanted depressions at the tip, but the aerofoil section is close enough:

 

DSCF9556.jpg

 

With the wing shaped to the correct size and profile I could drill the holes for the booms. I do not like to let good, practical ideas go to waste so I employed the same basic technique to drill the holes for the booms as I have used on my 1/72 scale pusher builds. First I draw a line which runs from the undersides of the leading and trailing edges of the wing to a point vertically beneath the rudder post. The angle between this line and the boom on the side elevation drawing gives me the angle that I have to hold the drill chuck against the wing when I drill the hole. I taped the sub-structure to the plan drawing so that the wing is exactly in the correct position and then held the hand chuck so that it is in line with the boom on the plan. A piece of paper with the correct angle as measured from the side elevation diagram steered me to a nearly correct angle to the horizontal for drilling. I used a smaller diameter bit than the brass rod which I will eventually use for the boom

 

DSCF9562.jpg

 

and then gently enlarged the hole with a needle file:

 

DSCF9563.jpg

 

By offering the brass rod to the hole I could use the plan to make sure that the alignment was correct. To achieve the correct final angle of the boom from the horizontal I placed a block of wood 22mm high, 12.6cm from the trailing edge of the wing (actually the front edge of the block was laid over the leading edge of the horizontal tail unit on the plan: that is 12.6cm from the wing). The hole in the wing could then be enlarged until the rod rested on the wood block: voila the rod has the exact angle and orientation.

 

DSCF9565.jpg

 

The above procedures had already been carried out on the upper wing, and I had added the ribs and filled and sanded them, so I was able to check the alignments of the booms by resting the tip of the upper wing on a paint pot and the other end on the nacelle. The tips and leading edges of the wings were squared using a small set square and the alignments of both booms checked: the upper boom should be exactly in line with and above the lower one, although their respective angles in relation to the wings are different.

 

DSCF9558.jpg

 

DSCF9559.jpg

 

Please do not let anyone ever tell you that scratch building a pusher is a) difficult, b) complicated, c) needs expensive tools and jigs: I am demonstarting that they do not. All of this was done on my work tray and desk top!

 

The ribs were made from 10 x 30 thou strip glued with liquid cement after the ailerons had been cut off:

 

DSCF9575.jpg

 

Mr Surfacer 500 followed by Mr Surfacer 1200 was used to fill the sides of the ribs and riblets, and then the sanding and filling began. When I thought that they were almost ready I applied a thin coat of primer and continued with the filling and sanding....

They are now ready to paint.

 

The wing structure on the port (left) side has been given some thought. It looks complicated, but when broken down it is not really. I had some spare wing ribs becuse when I was making them I forgot that some ribs have two gaps between the spars, and some three. I had only made ribs with two gaps.... hence the spare ones. I started by sliding the ribs on to the brass bars which represent the spars on the real aircraft. When the ribs had been aligned over the plan of the wing they were superglued to the brass bars. A lenght of 40 thou rod was glued to the front ends of the ribs to represent the leading edge:

 

DSCF9599.jpg

 

and 10 x20 thou strip was cut and bent gently with tweezers before being cemented with liquid cement to the rod to make the riblets:

 

DSCF9601.jpg

 

A coat of thinned Revell acrylic ochre (88) was applied before the next part of the assembly:

 

DSCF9603.jpg

 

DSCF9605.jpg

 

That was adding the rigging. I used monofilament thread and passed it between the rib and spar at the relevant points. I had drilled some holes in some of the ribs because I thought that I might fill the gaps between the ribs and spars with paint, but that did not happen and I will not be drilling holes in the ribs which i will put on to the wings:

 

DSCF9606.jpg

 

Now the structure could be completed by adding the narrow reinforcemnt pieces from 10 x 20 thou strip on the top and bottoms of the ribs, and the wire trailing edge. I used thin copper wire for the latter but it is too bendy so on the actual wings I will use some slightly thicker wire:

 

DSCF9608.jpg

 

DSCF9609.jpg

 

Concept proved. So now to paint the solid parts of the wings, add the roundel on the underside of the lower wing and drill the strut and rigging holes. The I can take off the nacelle cover and continue to add more interior details there.

 

Thanks for looking.

 

P

 

 

 

 

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On 9/20/2018 at 10:38 PM, pheonix said:

patience - you need a large amount of that when scratch-building.

 

On 9/20/2018 at 10:38 PM, pheonix said:

everything I do is a tribute to Heath-Robinson

 

On 9/20/2018 at 10:38 PM, pheonix said:

This model is turning into a "how-to-learn-from-mistakes" exercise.

Crikey, Phoenix, are you a mind-reader??

 

This is fantastic to see - every day a school day etc. I wish I had as much patience! I still think the scale stitching is brilliant!

Jon

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I had somehow missed this until now - maybe becauae I am loitering in the maritime section a lot at present.  This is fabulous; great techniques, lots of patience & persistence, and stunning outcome.  Wonderful.

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Just caught up on this - you are certainly using every modelling technique in the book! The central nacelle looks great with the stitching.

 

I do wonder a little about the side-to-side balance if one side is open and the other side clothed. To sit on its wheels and not rest on a wheel and a wingtip the CoG needs to fall laterally within the wheelbase. Hopefully the brass spars will be most of the weight and equal on both sides, and the ribs will balance out the plastic sheet covering to some extent.

 

Questions of balance are currently uppermost in my mind after I nearly ran out of places to hide noseweight in a B-26!

 

Regards,

Adrian

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8 hours ago, AdrianMF said:

I do wonder a little about the side-to-side balance if one side is open and the other side clothed. To sit on its wheels and not rest on a wheel and a wingtip the CoG needs to fall laterally within the wheelbase. Hopefully the brass spars will be most of the weight and equal on both sides, and the ribs will balance out the plastic sheet covering to some extent. 

 

 

This is a problem that occurred to me some time ago, and now that the solid part of the wing is fitted it has loomed even larger. I think that the ribs and othe structurs will compensate for the weight a little but not sufficent to prevent the model leaning on a tip skid. I am therefore planning to show the aircraft as if it was being tethered with guy ropes - one per underwing skid. In that way I can pull the lighter side and hopefully prevent it from leaning. That at least is the plan....

 

On 11/5/2018 at 3:00 PM, Marklo said:

Isn't every scratch build. This looks like it will be amazing when finished.

Yes they are, but this one is teaching me more than usual for my builds. In part this is because I am not used to this super-large scale - everything is so visible.

 

P

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