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Max Holste Broussard 1/72 Scratch Built Masters & Models

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  • 2 months later...

There's been a pause on this project due to some necessary house repairs, but I got back to the project late morning today. The task for today was the cabin windows. For this I planned to cut them out of very thin styrene which would then be glued to the side of the modelboard cabin section. Two over long pieces of thin styrene were cut, and cyano was applied in a tiny strip along the end of each piece. The two pieces were then pressed together until stuck. This left me with the two pieces fastened by the ends, allowing my to cut two identical parts. A print out of the windows was then attached to the plastic with double sided tape. I then sharpened the tip of my scalpel on a diamond stone before slowly starting to score around the frames, one by one.




The cabin block then had to be thinned by the thickness of the styrene so the overall width would remain correct. The block was wet sanded on some 240grit wet and dry. It is seen here being tested for thickness. On the final model, there will of course be the need to fill this seam, which will be between the normal resin fuselage and the clear resin cabin section.




It was a fiddly job but I'm pleased with the way it went. I'm back at Breighton this weekend, so will have another chance for a close look at the real Broussard.



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The window frames were glued to the cabin today and the cabin bolted back onto the rest of the fuselage to allow blending of the two parts. To do this I had to open up he holes in the underside of the cabin, and epoxy some M3 nuts into the bottom. This would allow bolts to pass through the holes still in the main part of the fuselage to hold it firmly in place for filling and sanding. There was other stuff going on today so didn't get much else done. 




Building the windscreen frames will be next around the front, and the first of the side windows needs an additional small dividing frame that runs parallel to the sloping front edge.




Since I'm back at Breighton this weekend, I'm taking the pattern along in its current state and will see if I can generate any more interest for one, assembled or in kit form.



Edited by Army_Air_Force
Spelling - missed letter
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The fuselage top extends over the centre wing section. This required an area building up on top of the wing. Electrician's tape was used to control the area where the filler would be applied.




I also started cutting and gluing microstrip for the front framing.



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The centre frame is now glued on, but the rounded corners on the frames haven't been reproduced yet. The rear fuselage also needed building up a little to blend smoothly into the wing. The layer of filler is only around 0.5mm thick.




The filler needs a little more work yet, but I ran out of time to do much more, and wanted it presentable for the weekend event rather than plastered in unsanded filler.



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  • 1 month later...

Time today was split between a customer's Pitts Special and the Broussard. On Bruce, I was working on the intakes on the cowling. This strip of styrene will form the carb intake, but as it needed to be slightly thicker, it was glued to a larger sheet of 0.25mm styrene. Once hardened, it would be cut out and trimmed to shape. This would also involve heating one end with a soldering iron to allow it to curve over the front edge of the cowl.




The oil cooler was to be part styrene and part modelling resin. There was a flat strip of styrene that needed to be glued to the bottom of the cowl first, with the resin part on that. At around 4mm wide, it was a nightmare to hold and sand with my sausage fingers!



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  • 1 month later...

There's been a few delays due to other customer projects, but I got back to "Bruce" today. Fin was scribed first and hole drilled for the counterweight..




Next I moved to the fuselage doors, cut from 0.25mm styrene. A fiddly job. The fin and doors swallowed 3 hours of the day!



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The cowl took some plotting of where the exhausts and panel lines went. I made a scribing too to cut the cowl gill lines around the odd shape.




However, things don't always go to plan! While the tool was great, making the tool with the cowl front edge as reference and then sitting the cowl on its back edge for scribing put the lines in the wrong place, so they had to be filled and left to dry for another go. Must pay more attention next time!! Then it was time to pick my daughter up from school and there was another day gone!



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I got the cowl panels partially scribed today, but it wasn't an easy job due to the mix of filler and model board used in its construction. For that reason, I've decided not to panel the fuselage, but to mould it first, take a pure resin version which can then be scribed and a second mould made. Having a fuselage made from the one material will make the scribing much easier and means I won't risk damaging the master pattern if the panelling goes wrong. I'm not looking forwards to scribing around the fuselage. I finished the windows on the fuselage too, adding the small frames on the front windows and the join in the sliding window where the gun sticks out.




Here's the tiny tail wheel. Turning the 4mm diameter was fun!



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  • 2 weeks later...

With Christmas just around the corner, I don't have money to spare for silicone and casting resin just now. So I fancied a change of pace and turned my attention to the decals. Using measurements and pictures from the fullsize and scans of the model parts, I set about producing the master artwork for the decals. The graphics could be trial "fitted" using a layers in my photo program to check and adjust the size against the model. This scan has the fuselage side flat against the scanner, but I did another with the tapered rear fuselage flush with the glass.




The model parts were added into one photo layer and the photos of the original aircraft added in a layer over the top. Everything was enlarged to four times model size to make the tracing easier. Each colour was then traced in black on separate layers so I had a red, white, blue, black and orange/yellow layers, but all in black. This would allow printing of each colour separately or I could colourise and combine layers for a full colour print, depending on how my decal maker wanted to do it.




The image below shows the progress so far. Each colour is actually completely black at present, but that would mean the roundel and rudder would be just one black splodge. So the yellow, red, white and blue layers have all had their transparency adjusted so they show up as different greyscales to show each different colour.



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  • 4 weeks later...

No progress of late. My workshop was taken over by some essential bodywork repairs on my 1/1 scale Jeep. Both the front right fender and right side of the body needed some attention to deal with rust and age fatigue.


While I was using the workshop for welding and angle grinding, it was in too much of a mess to do any modelling, but I wanted the work done before it got too cold and damp to do the repairs and painting.


It's all back together now and the floor and benches swept clean again, but now I'm suffering from "Christmasitus", that "can't be bothered" feeling as you approach a holiday period!!


I'm hoping to get some fun modelling done with my daughter over the holiday.


Fender repairs to the corner and "hat channel" that reinforces the panel and inner skin of the fender.





The step and a little further back on the body needed some welding too.




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  • 1 month later...

Yesterday, I got a delivery of silicone and casting resin and did a couple of small castings to test the properties of the resin. I also made a bending template for the landing gear. The cowling is awaiting the engine casting.




Yesterday I began to box up the parts ready to make moulds.



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Centre section, tailwheel and fin/rudder.




The fuselage mould is just the first step to making the final mould. The cowl is made from different materials and that caused difficulties scribing the panel lines. For the fuselage, I'm going to make a resin version to scribe the panels as it will all be one material. I'll then make a second mould for the final casting.



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Over the last few days, I did some test casting with the resin. I was only mixing very small batches to see what it was like. I got some slow cure, which has a pot life of around 8 minutes - plenty of time to get the resin into all the small details without being rushed and without having to vacuum the moulds. I was using two moulds I'd made earlier in the rpoject. One was a set of wheels while the other was a radial engine. I needed the engine which would be cut down in diameter to fit into the front of the cowling.


The first test didn't set hard. This was either due to getting the mixing quantities wrong due to using such small quantities ( around 4 to 6 grams total ), or due to the very small parts not generating much heat in the initial phase of the cure. After they'd been "green" for a while, I put them in the airing cupboard over night, but they were still soft the following day.


For the second test, I tried to be very carefull to weigh out as close to identical weights as possible - still tricky at 3 grams per pot. Once all the moulds were poured, they were left on top of a convection heater to put some more heat into the small parts in case they weren't generating enough themselves. After an hour, they went up to the airing cupboard over night.

They were opened up on Saturday morning and had fully cured and were nice and hard, and the very watery resin had picked up the detail nicely. The engine casting was trimmed down later in the morning and glued into the cowling so that was ready to mould.



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Today, after boxing the cowl and landing gear template, I started mixing rubber. I had to come into the dining room, rather than the workshop, as I just couldn't get the workshop warm enough for the minimum temperature of the silicone. Unfortunately the 1.1Kg bottle of silicone wasn't quite enough to mould the main wing panels, so I had to order another bottle. That should be here by Tuesday or Wednesday.



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After a night in the airing cupboard, the moulds were removed and the styrene box carefully cut awat along the glue seams. One by one, starting with a none Broussard mould, the rubber was peeled away from the master patterns.




Here's the cowl and gear jig mould and masters, now separated.



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The edge of the rubber was trimmed where surface tension had curled it up the sides of the styrene box. This would allow the mould to sit flat on the bench for casting.




The moulds were all cleaned up across the morning and the bench cleared and prepared for casting. That gave me time to get the workshop warmed up. In addition to the Broussard, I had some other moulds ready in case I mixed up too much resin. It turned out I mixed up quite a bit extra! So after the Broussard parts were all poured, I cast the spare moulds.



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Early evening, I started removing the castings from the moulds. The rudder had a small air bubble, so I sliced trailing edge of the mould with a new scalpel blade to allow my poking skick to work the resin in better next time. The surface detail in the tail, fin and wing were there, and engine detail in the cowl. The most delicate parts were the tail wheel and prop which also formed well. The glazed area was cast in cream resin as a first test of the detail and to clean the mould prior to doing a clear resin cast.




Here's a close up of the cowl and tail wheel. Later in the evening, I poured some more castings which will be ready tomorrow. Perhaps the new batch of silicone will arrive tomorrow and I can get the main wing mould made. For now, the next job will probably be to scribe the fuselage casting with the panel lines. 


It's nice to see it like this after so long measuring, carving and sanding. It's almost a year since I went to Breighton to do my day of photographs and measurements.



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