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1/72 Blackburn Twin scratchbuild


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Evening All

 

Thanks Pete, Dennis, Charlie, Stuart, Torbjorn, and Steve for the encouraging comments.

 

Steve: I do not know the Strutter kit so I cannot comment whether trying to use the fuselage would be a short cut for this model. There is a strong similarity in the shape of the fuselages but I am not sure about size. In any event if you have suitable engines and cowlings, building the rest of the fuselage from scratch is not such a difficult task.

 

Writing about engines I made two from a piece of sprue which I filed to the correct size for the centre and then added the cylinders from thick rod. I scribed the cylinders to represent the cooling fins and used thin rod for the push rods on the front.

 

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The second fuselage was completed in the same way as the first and then I could cut out and add the fins to both. I also added the cockpit coamings at the rear from thin rod. The observant modeller will see just how much filler was needed to fair in rear fuselage decking on the second fuselage! One of the problems of these limited run kits is that sometimes the fit is not as good as WNW for example!!?

 

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With the fuselages complete I could glue them to the lower wing. I did this one at a time and placed the wing and fuselage over the plan to make sure that all was correctly aligned: which I am pleased to report is the case!

 

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Unlike the fuselages the wing to fuselage joints needed almost no filler at all - so sometimes limited run kits can be good after all. However the underside of the fuselage should protrude slightly below the under-surface of the wing so to make this look more realistic I cut some thin pieces of 20 thou card which were shaped to the under-wing profile on one edge and straight on the other. These were glued under the wing to align with the sides of the fuselages and then the gap between them had some card glued in place and finally liberal amounts of filler - which is even now setting so that I can start to sand and level it:

 

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Thanks for looking.

 

P

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  • 2 weeks later...

Evening all,

 

Many thanks gentlemen for the very kind and encouraging comments: I really appreciate them all.

 

I have done some more construction work and painted the bulk of the model and it is beginning to look like what you see in the photos. I completed the horizontal tail unit by cutting and inserting between the rear fuselages a piece of 30 thou card with Evergreen strip (10 x 20 thou) ribs. I also added the small units on the outer sides of the fuselage plus the tail bracing, and then the two rods which were set between the forward parts of the fuselages: I assume that these were for the engine controls on the starboard side (the pilot sat on the port side).

 

Painting followed - mainly acrylics for the upper and lower surfaces but Humbrol enamel white for the floats because I have some left from the past and I find that it gives a better coverage than the acrylic paint. The struts were Revell SM 382 which is another enamel - I just like the soft brown to represent the pine of the struts. The cockades were home printed and the serial came form an old set of RNAS/RFC numerals from Pegasus. The rudder stripes were painted:

 

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The white dots on the upper surfaces are holes for the struts. To put the top wing in place I used a procedure which I have found from experience is most suitable for multi-bay biplanes. I put some of the cabane struts into the lower wing - in this case the pair on the inner side of each fuselage, and the outer pairs of main wing struts. I used ordinary styrene cement and placed the inner struts against the fuselage sides first, then quickly added the two outer pairs and lowered the top wing. I had put drops of cement into the respective holes in the top wing. I was lucky because three of the fuselage struts fitted exactly and the fourth only need a minor adjustment. The outer struts were a little more fiddly but still went into place quickly. The whole assembly was jigged with paint pots to keep it square while it dried out overnight. The result was what I desired:

 

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This structure was quite robust when dry and allowed me to put in the remaining struts, one at a time, without problems. After these had been put into place I again left the assembly for a couple of hours to set properly before I added the kingposts on the outer parts of the top wing:

 

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The model is now ready to add the floats and that will be the next stage.

 

Thanks for looking.

 

P

 

 

 

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Amazing build - a lot of plane to drop just 70lb of Ranken Darts on a Zep! Ok I know it would have been more if the 150HP Smith had worked, instead of being replaced by 100HP Gnomes, but I would have thought they could have given the chap in the other fuselage a gun of some sort as well. Rigging could be fun!

 

Pete

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On 12/3/2019 at 8:00 PM, Torbjorn said:

 

Thanks for describing the assembly procedure. I have only put together a multibay biplane once, but my method was less efficient.
 

I developed this technique as a result of trying to build pusher biplanes and have used the method since with success. Here are some examples of my method from earlier builds:

 

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This was an FE 2b conversion: the photo shows clearly the outer struts only were put into place because the upper boom was supposed to rest on the rudder: what happened was that the expoxy holding the booms to the upper wing failed and the boom dropped off! However the top wing stayed in place because the struts were secure and I was able to re-attach the boom. The cabane and remaining interplane struts were added afterwards.

 

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Another conversion - this time the DH 1A and I used the same method of attaching the outer interplane struts and used the rudder as the third support. Adding the cabane and remaining interplane struts was very straightforward. In both of the above cases the assembly was strong enough to be handled easily and gave no indication that it would fall apart while extra struts were added.

 

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This is a scratch built Ago which had twin booms joined by a single tail unit so I had to assemble the wings first. Here I did put in the cabanes with the outer interplane struts because the structure would have been too weak without them. Jigging this was easy as the struts are vertical so a simple jig kept everything in line while the cement hardened:

 

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The method can also be applied to kits where necessary, but always give the cement plenty of time to harden and use at least 4 attachment points so that when you want to handle the model it has sufficient rigidity to be lifted and turned at high angles.

 

These are examples of where I only used the cabanes as fixing points:

 

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Avro type D biplane (1912).

 

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Maurice Farman Longhorn: note that the tail struts help this structure but only the cabanes hold the wings.

 

All of the above are multi-bay types.

 

Hope this helps.

 

P

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She's looking good P!

It looks as though you may have a problem with the roundals not settling properly though. From here it looks like there are gaps under them.

 

Ian

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Evening All,

 

Thanks to all of you who commented on my last update - I should have replied sooner but even as I was posting the distraction on how I put struts into multi-bay biplanes I was beginning to get some aches and pains associated with a horrible bug/cold which has made modelling life somewhat difficult. It also meant that my intention to leave a response was shelved: I apologise for not having commented and thanked you all sooner. Adding the floats while in a state of incomplete concentration and having a shortage of patience has been a lesson in itself - next time I will wait until I am feeling a bit better....but the deadline looms!

 

The rear pair of floats were fixed using 20 thou rod cut to length: first one side was fixed and then the other was made so that it matches from the side and longitudinally. The struts are not vertical so this operation would have been tricky even if I had been feeling normal. As it was it took three attempts to get the second float properly aligned. The struts were painted after I had calmed down.

 

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That left the two large floats at the front. These too had to match both from the side and be properly aligned longitudinally and again the struts are not vertical with respect to the bottom of the fuselage or thrust line. There is also a cross strut between the forward and rear pairs and there were fixings on the floats to allow the angle of incidence to be changed - this was an experimental type. Knowing from experience that fitting one float would be relatively straightforward I decided to tackle one side and then wait until I felt better before tackling the other. I will not give a blow by blow account but Burns' memorable lines about "best laid plans of mice and men" assumed significant proportions while I was trying to get even the first float properly aligned. The second finally submitted after a real struggle: I have not had such problems that these presented for a very long time. But they are there now....and the aircraft is a tail sitter! But I have a cunning plan - to which I mean that I intend to mount the model on small carriages and trestles as per the photos of the machine represented by the model when it was at RNAS Grain in 1916.

 

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And before anyone comments I have still not properly softened the cockades on the upper wing: I have not had the patience left to deal with that yet!

 

When I am feeling considerably better I will rig this model and add the final details. In the meantime I am making a small base and the carriages and trestles which require much less concentration and can be picked up and put down easily.

 

Thanks for looking.

 

P.

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On 12/5/2019 at 3:11 PM, pheonix said:

Hope this helps.

It does, thank you. I like your solutions.  I’m a fan of simple is good and finding the easiest solution of least resistance (ok I’m lazy) to each (potentially complex) problem, and it looks like you adhere to that too :) 

Floats look perfectly aligned from here, and look like identical twins too.

Edited by Torbjorn
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