Author Topic: Scratch build partial stripdown Vickers FB 5 Gunbus 1/32 scale  (Read 4985 times)

Offline lone modeller

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Re: Scratch build partial stripdown Vickers FB 5 Gunbus 1/32 scale
« Reply #60 on: November 20, 2018, 10:19:49 AM »
Evening All,

Thank you Gregory, Rick, Andreas, Ryan and Bud for your encouraging and supportive remarks. I have been in need of them recently because I have just tackled what has up to now been the most difficult part of the project: soldering the upper wing boom.

Some of you will be aware that I have considerable form when it comes to building pushers, albeit in the True Scale. My preferred method is to attach the tail booms to the wings, put the top wing into place with the rudder post in support at the rear, and then add the boom struts. In this way alignments are very much easier to achieve and the modeller does not have to handle two fragile structures while trying to attach them to the rear of the wings and align them correctly with the rudder post. I am using my tried and tested method on this model. However there is a big difference with this model because it is a larger scale and I have to solder 2 of the 4 booms to the rear spars of the wings which means that the boom alignment has to be very accurate or the structure will simply look awful or worse. I have been giving this problem considerable thought for some time but I could prevaricate no longer.... so I consulted William Heath Robinson for advice which he generously gave to me.

First I masked the solid part of the wing with a plastic bag and then laid the assembly on the plans and aligned them.



I placed the fuselage nacelle/lower wing assembly over the top wing:





The position of the boom/rear spar joint of the lower wing could be copied on to the rear spar of the top wing. This was essential because the two booms must align exactly even though they are not in the precise position over the plan (they are approximately 0.5mm too close to the fuselage nacelle). The lower wing assembly was set aside and the top wing laid on a block of balsa which will be the base for the soldering process. The balsa block was placed on the plans so that the wing is directly over the plan as allowed me to use it to align the brass rod which I will use for the boom. A second block of wood was laid on the plan with the edge along the leading edge of the horizontal tail unit. The brass rod was laid so that one end touched the rear spar and the other was resting on the second wood block and was over the boom on the plan. To get the correct height at the tail end of the boom I had to add some pieces of plastic card:



I will briefly explain the simplicity of this method which I have used many times - I have converted or scratch built 10 pushers this way so far, and have not had a problem yet. Tail booms have to conform to two angles as explained in an earlier post. Aligning the angle in relation to the vertical centre line is easy - just lay the wing and boom over the plan. The angle in relation to the thrust line can be achieved by using the height difference between two easy-to-measure  points on the boom:



The diagram above shows the distance 'a' between the trailing edge of the wing and the leading edge of the horizontal tail unit. The height 'b' is calculated from the side elevation of the aircraft in question by drawing a line (2 on the diagram) which touches the leading and trailing edge of the wing and is continued under the leading edge of the tail. Height 'b' is the distance on the plan between line 2 and the boom on the plan (line 1). Therefore the rear of the boom resting on the wood block has to be the equivalent of height 'b' above the balsa block on which the wing assembly is resting.

To lift the boom rod so that it made good contact with the centre of the rear spar I used a file and then held it in place with paint pots as advised by H R:





I checked the alignment with the lower wing assembly by placing the latter over the former:



I removed the lower wing assembly, put flux and solder paint on to the boom-spar joint, and after checking and adjusting one last time to make certain all was in its correct position I heated my soldering iron and used solder wire to reinforce the joint. The result when  I placed the lower wing over the new upper wing and it looked like this:



The remainder of the top wing assembly followed the procudures I have already described.



and the two wings look like this:



I have still to make the ailerons and add the trailing edge and tip wires to complete these structures.

Unfortunately this is as far as I will be able to take this project for the time being as I now have to go on one of my periodic journeys, this time for an undetermined period. I simply do not know how long it will be before I can pick it up again but I am hoping that it will only be 2-3 weeks: fingers crossed. Until then I hope that you all have an enjoyable time with your own projects.

Thanks for looking.

Stephen.

Online lcarroll

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Re: Scratch build partial stripdown Vickers FB 5 Gunbus 1/32 scale
« Reply #61 on: November 20, 2018, 10:53:42 AM »
    The master of the improvised jig strikes again, sheer genius Stephen! This is going to be a Model to be reckoned with, it's already in it's own league. I'll be waiting for your return and restarting of this project with eager anticipation.
Cheers,
Lance

Offline p9o1r1sche

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Re: Scratch build partial stripdown Vickers FB 5 Gunbus 1/32 scale
« Reply #62 on: November 21, 2018, 03:07:24 AM »
I'm just catching up with this thread.  Great work, Stephen!  This project appears very complicated and you are tackling it like a pro.

Kudos.


Ken M
Ken M.

Offline Bughunter

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Re: Scratch build partial stripdown Vickers FB 5 Gunbus 1/32 scale
« Reply #63 on: November 21, 2018, 06:42:45 AM »
Beside your great work I like the idea of half strip down / half real one model more and more.
I have to build another D.H.2 beside my strip down for the same effect.

Looking forward to next updates.
Cheers,
Frank 
Wikipedia says: A model is a simplified representation of reality.
So I create downscaled originals.