No 1A de Haviland: 1/32 stripdown Airco DH 1A

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2 months 3 weeks ago #286 by Stevef
Evening All,

I have finally bitten the bullet in that I have soldered the lower wing spars to the nacelle frame. This is one of the most tricky parts of the assembly - if this is not completely accurate then the rest of the model will look distorted and unbalanced. In brief the spars have to be laterally dead centre to the nacelle, the centres of the spars have to be perpendicular to the sides of the nacelle, and the spars have to be at 90 degrees to the fore - aft line. Usually with wings there is a tab or interface between the end of the wing and the side of the nacelle which provide surfaces to join the wings to nacelle/fuselage , but in this case the spars are fixed to four points at the bottom and rear of the nacelle: if any of those are mis-aligned it can have unfortunate, not to write disastrous, consequences.

Before I soldered the spars I had to solder a piece of brass rod to the upper nose - this represents the upper part of the frame in front of the observer - a machine gun mount and a folding split windscreen was fixed to this on the real aircraft:



With this in place I proceeded to mount the spars. I put a rib on the ends of the spars to ensure that they were the correct distance apart and they could not move together or apart. I had carefully measured and marked the centres of both spars and these were lined fore-aft up as accurately as possible. The spars were placed on the bottom of the 4 vertical frames at the rear of the nacelle and the height of tips of the spars to the top of my desk measured - these had to be equidistant or the spars would not be properly aligned with the nacelle and one wing would be higher at the tip than the other. Minor adjustments were made until this was right. The the set-up was jigged so that the centres of the spars were in the centre of the nacelle frame, and that the spars could not move sideways or fore-aft while I wielded the soldering iron:







Having taken several deep breaths I proceed to solder and hoped that nothing moved while I was working. The result:





I have now got to write the instructions for the next stages of construction because I need to prime and paint the metalwork of the nacelle but do not want to prime the spars until later. This is that the ribs slide along the spars and strip the primer from the meta but I have to attach a rib flush to each side of the nacelle and these and the nacelle frame have to be painted first, and have holes for double lift wires drilled into them. I also need to consider carefully how and what to assemble inside the nacelle before i work on the wing ribs - which incidentally also have to have bracing wires. I intend to use my previous experience with the Gunbus, but some things are very different on this model and have not been fully worked out yet. However I am hoping that the next post will not be a bit quicker than the current ones.

Thanks for looking.

Stevef.

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2 months 1 week ago - 2 months 1 week ago #287 by Stevef
Evening All,

I have had the great good fortune to be advised by another modeller (Dennis) on Britmodeller of the existence of drawings by W. Wyman of the DH 1A which have quite a lot of information about the cockpit details, (and from which the drawings in the DataFile were almost certainly copied). This means that I am now able to reconstruct something closer to reality in the nacelle. This has meant that I have had to make several alterations to the nacelle frame and other changes. At least I have this information at a time when I can use it constructively without having to conduct major surgery or start afresh.

The first change was to remove the vertical bar in the rear nacelle bay and replace it with a bar from plastic strip further to the rear. Before:



after:



The bottom frames were also added from plastic strip, followed by the lower curved section in the front of the observer's cockpit. The vertical bar in the nose was soldered to the two half-rings:







The metalwork was primed, and bulkheads fixed to the rear of the pilot's cockpit and between the pilot and observer cockpits. The remaining cross members of the nacelle frame completed this structure including two engine bearers in the rear. The frame was painted with acrylics and the bulkheads with oils - the latter were coated with Revell clear orange varnish when the oil paints were dry:





At last I should be able to start adding the internal details to the cockpits.

Thanks for looking.

Stevef.
Last Edit: 2 months 1 week ago by Stevef.

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2 months 6 days ago #288 by Stevef
Evening All,

I have rewritten the instructions several times as I try to work out the best way of going forwards with this one. Originally I had intended to add the interior details of the nacelle and then proceed with the ribs on the lower wing, but then I realised that the pilot's seat, the engine and radiator would stand very proud of the top of the nacelle and would in all certainty be knocked off when I try to put the wing ribs into place. So a rethink or two later I decided it was safe to put in the observer's seat and rudder bar, after the seats and rudder bar assembly had been completed. The seats were mounted on plywood sheets resting on the nacelle frame, so they were represented by thin plastic card:



I am still not sure that I am happy with the seat belts - I may replace them later. The observer's seat and the rudder bar were fixed in place:





The wires in the second photo are from the ribs nearest the nacelle: these have been painted and rigging and bracing wires inserted because it will not be possible to reach here later on in the build when I want to start rigging. I also inserted the next three ribs between the nacelle and the boom attachment point on both sides of the nacelle. The booms are from brass rod and were soldered to the rear boom: the ribs against the nacelle were far enough from the soldering iron and hot metal that they did not melt. I did not photograph the jig for soldering on this occasion but it is simple enough to describe. I set the nacelle sub-assembly on a block of balsa wood and placed the brass rod booms over a copy of the plan. The height of the rear end of the boom relative to the spar is calculated from the side elevation drawing as follows:

a. draw a horizontal line from the rear of the rib to beneath the rudder post;

b. measure the vertical distance from the bottom of the rudder post to the line. This distance is the height that the rear end of the boom needs to be above the rear end of the spar on the model.

Now a block of wood or other support can be set at the correct height relative to the nacelle sub-assembly and spar and the ends of the booms placed on it.

With the booms soldered and the joint cleaned the inner ribs could be slid into place and set with CA:



To get the ribs accurately into place on the opposite side I had to pin the structure to the balsa block and pull the ribs over the plans:

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2 months 6 days ago #289 by Stevef
The ribs outboard of the booms could now be put on with some of the flying wires attached via holes in the ribs, as I do not wish to use turnbuckles. Personally I think that the items available on the aftermarket are too large to be realistic, and in addition trying to fix them on parts of this model, (the brass bar nacelle frame and brass rod booms), is not possible. However it does mean that I have a tangle of threads on both wings which I am sure are going to be a real pain during the build until I fix the top wing and can put them into place:







Two small ribs are missing from the wing tips - these are being left off at the moment as I have decided that the brass bar alone is too thin to represent the spars accurately so I intend to add strips of 30 thou plastic to the top and bottom. If I put the last two spars into place now I know for a fact that I will have to put them on again after I have knocked them off!

Thanks for looking.

Stevef.

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2 months 23 hours ago #290 by Stevef
Evening All,

Thanks all for your continued interest and support, it is greatly appreciated. The funny thing about scratch building is that it often takes a long time to make things and progress seems to be going nowhere, then suddenly a lot of things come together and a model really begins to take shape. This is certainly true in this case as I started this months ago and for a long time had nothing on my desk that even remotely suggested that I was making a large model. Now in a few days I can see what has hitherto just been in my imagination beginning to become real.

I checked again the width of the seat belts and found that although they look wide, they conform to the size of contemporary lap belts as used by the RFC so I am not going to replace them after all.

Fixing the ribs of the lower wing to the spar has set things in motion: I have now finished the construction of the lower wing except for the ailerons which I will make later. The compression ribs on the leading edge were CA'd into place - some minor adjustments had to be made to some of the ribs to bring them to the same thickness as the main ribs, but generally they fitted well. I decided that the brass rod was too thin to represent the spars on the real aircraft so I have CA'd strips of 30 thou plastic to the top and bottom of the bars to make them equal thickness to the ribs as on most contemporary aircraft:







The two small wingtip ribs were added at this stage as they were now less likely to be knocked off by handling. Next was the leading and trailing edge frames to the wings - from 20 x 30 thou Evergreen strip. Two small braces on the ribs closest to the nacelle and central strips on the upper and lower edges of the ribs completed the wing structure for now:









I will paint the wings next while I decide whether to make the top wing or add the nacelle details to the existing structure. Either way I am eventually going to have to set a large fragile structure to one side while I work on the other so that no damage is done.

Thanks for looking.

Stevef.

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2 months 1 hour ago #291 by Stevef
Evening All,

Continuing the theme that scratch building seems to reflect the course of evolution - long periods when very little happens punctuated by periods of very rapid change - I have now completed the painting and internal rigging of the lower wings. This is an important stage because I can now add many of the internal details of the nacelle and install the engine, radiator and fuel tank before proceeding more slowly once again with the top wing and tailplane.

Here is the painted structure - a mix of Revell Oker (88), fiery red (330) and Humbrol insignia yellow (154).



When the paint was dry I rigged the internal bracing of the wings using some of the pre-placed threads which had been a nuisance beforehand - now at least there are 4 threads less than before!





I am planning to put on a coat of clear orange later to even the tones of the wood and give a slight sheen, but first I want to complete the details described above.

Thanks for looking.

Stevef.

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1 month 3 weeks ago #292 by Stevef
Evening all,

After a great deal of umming and ahhing I decided that I would complete the current sub-assembly (nacelle and lower wing), before I make the upper wing and tail plane. Then I had to decide whether to add the pilot's cockpit interior details or the engine and radiator: either way I may run into problems with bits sticking out and getting broken off or alternatively being in the way.... Eventually I decided to add the engine and radiator first, so I completed the oil tank by adding the support brackets and the exhaust and painted them all. The engine was glued to the mounts which will later rest on the nacelle frame:



The oil tank was attached to the side of the engine and a pipe to the oil pump made from copper wire. The exhaust has been added for the photo - I will not glue it into place until I have attached the water pipe to the top of the engine:



The fuel tank was placed in the nacelle under the engine bay and two straps added from 10 x 20 thou Evergreen strip - I am not sure whether these were used but they had straps on the FB 5 so I am guessing they had them here too:



The radiator was fixed to the nacelle frame behind the pilot's cockpit - I assume that it was held on brackets and probably braced with wires on each side but there are no photographs so I am making this up as I go along:





The water pipe was fixed to the top of the engine and the engine sub-assembly glued to the nacelle frame so that the water pipe fitted into a hole drilled in the top rear of the radiator:





I have still to add the carburettor system to the left side of the engine and then there are various wires, pipes and a control horn on the magnetos which are not included in the kit. I will add the exhaust pipe to the engine after I have put in the seat and other details in the pilot's cockpit. More on those details later.

Finally for the moment I have made some of the fuel pipework and taps which were fixed to the bulkhead in front of the pilot. These are from copper wire and plastic and are ready to be bent to shape:



If you have been, thanks for looking.

Stevef.

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3 weeks 4 days ago #293 by Stevef
Evening All,

I have been away a lot recently visiting family so have not had much time for modelling. However recently I have managed to make a little more progress and here are the results.

I have added some more details to the pilot's cockpit in the form of the seat and bench, control column (from rod with thin wire for the grip), and elevator bar, hand pump and pipework for the fuel, and pulleys for the control cables to the ailerons and rudder. The photos are not particularly good as these parts are partially hidden and difficult to see even on the model itself:









There is still some touching in to do but that can wait until I have finished scraping paint to fix some other parts on to the nacelle structure.

I have also been working on construction of the top wing. It has the same composition as the lower wing: brass bar for the spars and plastic strip for the ribs. The ribs between the boom attachment points to the rear spar were put in a group in the middle of the wing and a single rib near the tips of the wing. This ensured that the spars would be correctly spaced and that the centre ribs would not be affected by heat when I soldered the booms to the rear spar. When threading the ribs care had to be taken to ensure that they were in the correct order as they are not all the same. The booms are 1/16 inch brass rod: these had the front tailplane spar, made from 30 x 80 thou Evergreen strip, inserted at the rear end. Because there is no incidence on the booms relative to the spars (ie the rear of the boom is at the same level as the spars), it was easy to make a simple jig to allow me to solder the booms into place. The spars and booms were placed over a plan of the upper surfaces of the aircraft and held with pins before the nacelle and lower wing was held over the jigged upper wing to make sure that the two sub-assemblies match as closely as possible. When I was satisfied with the alignments I soldered the booms. An after solder check showed that the minor mis-alignments between the upper and lower wings and booms can be easily corrected at the final assembly stage.



The ribs between the booms were aligned with the ribs in the lower wing but the ribs which will hold the cabane struts had to be aligned with the nacelle frame: all were CA'd into place:



The ribs outboard of the booms were CA'd: each one had to be measured against its counterpart in the lower wing to make sure that all are properly in line:



Now I have to add the plastic strips above and below the brass spars between the ribs to increase the thickness of the former prior to adding the compression ribs. Other details will also be added before I paint the wood parts of the wing. I have also got to think about and decide how I am going to construct the tailplane as that too will only consist of ribs and spars, but has to be strong enough to hold the elevators.

Thanks for looking.

Stevef.

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1 week 5 days ago #294 by Stevef
Evening All,

Evening All,

Once again I have been absent from home and as usual it takes a few days for me to get back into things - hence the delay in reporting. However recently I have been able to make some more progress, much of which has been repeat what I did for the lower wing.

I have continued slowly with the construction of the top wing. Having put the ribs into place I had to thicken the spars with Evergreen strip. The strip was CA'd into place as per the lower wing, leaving gaps on the underside where I will have to pass the rigging through the ribs later. When the rigging is complete the remaining gaps can be filled and painted.



The contrast between spars which have been thickened and those which have not can be seen in this picture of the upper and lower wings:



When the spars were finished the compression ribs could be inserted on the wing leading edge:







The rear of the booms were soldered to make a strong joint: later this will hold the rudder post and form an important part of the overall structure of the model so strength matters here:



The front spar of the tailplane has been CA'd too - this adds strength to the rear of the model. Later when the Evergreen strip that I have ordered arrives, I can build the framework of the tailplane on to this spar.

Meanwhile I have constructed the remainder of the framework for the top wing, including the leading and trailing edge strips, and the longerons across the span:





The metal parts of the top wing and the booms have been primed with Halfords rattle can primer: while this dries I am going to finish some details on the nacelle and engine and start to make the ailerons for the wings.

Thanks for looking.

Stevef.

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