Build your first flying scale model - Chapter 5 - Final fuselage work
OK, let's get back to working with balsa again, which is much more fun that wire (at least in my opinion!)
Here you can see the last stringers, which are added under the nose. I found I needed to adjust two of the slots in F.12 to get them symmetrical.
When the cement was dry, the stringers were sanded flush at the nose, and formers F.2 and F.3 added. below you can
hopefully see that I also decided to cut out the intake opening in F.2
rather than just paint it on.
Having already added some sheet inlay in the fuselage sides at the nose, I decided to now carry this on and sheet between the stringers
above and below the nose. Besides adding some useful strength where it is needed, this is also very satisfying
work to do, and a useful technique to learn for future models.
You could probably get away with using soft 1/16 sheet for this, but I prefer 3/32 if double curves are involved,
to make sure you can leave enough wood sticking up to sand down later to the correct contours.
Take a piece of soft balsa sheet, and cut a strip across the grain, so the width of the strip is just a
touch greater than the gap between formers F.4 and F.5. You can get the final fit using an emery board.
Offer up the wood to the longeron, and mark roughly where the next stringer up meets the sheet of wood (front and back).
Cut the sheet between the marks. Now offer it up to the space you are trying to fill, and see how the fit looks.
Using an emery board, sand the four edges until a snug fit is obtained, with the sheet sitting proud of the stringers
and formers. You will probably have to sand chamfered angles on all four sides. There will be a lot of trying for fit,
taking a bit more off, trying again, trimming a bit more, and so on. Try to leave no gaps at all around the edge.
If it takes a couple of attempts to get the piece to fit, then so be it you will get faster the more you do,
and because the wood is soft, shaping the parts is relatively fast. When happy with the fit glue in place with
the aliphatic wood glue.
As you work up the fuselage, the angles get more interesting, and you have to shape the bottom edge of the sheet before
you can mark the top.
Here is the completed filled upper fuselage
Next was the section at the bottom between F.4 and F.12.
The outermost pieces here were done a slightly different way, in that they were simply slid in from the side, and sit on the lower longerons
The centre two pieces are done like the upper cowling, and are let in as normal.
Once the glue is hard, the upstanding blocks of sheet can be carved roughly to shape with a sharp blade.
The stringers act as your guide as to how much wood to remove. Here is the nose prior to sanding.
Next, final shaping is carried out using emery boards, followed by a final polish with 600 grit wet and dry paper
(used dry, of course).
In this view you can see that I have also started to shape the nose laminations, and have rounded off the bottom corners.
As I mentioned, I find this work very satisfying to do, but as we are all different,
it is quite possible you will not. In which case, this step can be easily omitted at
least you have the side sheeting to get a firm grip on while winding the model.
I tackled the cockpit sides next. The kit design features a notepaper pattern which is glued over the balsa structure.
This is simple to do, but as usual I decided to change things, on the grounds that paper is easily damaged and creased by
careless handling of the model. I much prefer to use balsa for cockpit openings - in this case soft 1/16" sheet.
You can see in this photo how I used the paper pattern as a guide for cutting out my four pieces of balsa.
Here is the first piece glued in place. I have deliberately left it slightly proud. Final shaping of the opening
and blending back to the rest of the structure is done
after the glue is dry,
All four cockpit pieces have been fitted and shaped in this view. You can also see the two small filler pieces I added behind the
headrest to give me someting to stick the tissue to later. Also the sheet pieces for the rubber retaining dowel, and the scalloping out of the formers, both detailed below.
The kit shows a relatively large hole for the rubber dowel, but if you use a length of aluminium tube (fairly standard amongst
flyers nowadays) the hole does not need to be this large. I usually make the holes with a round needle file like this. Best to leave it a bit undersized at this stage.
Returning to those former scallops - this is the sanding block I usually use to help with this. Made by X-Acto, I have had it for years. I like the different shapes of the two ends ends - the
small radius is very useful when sanding between stringers that are very close together. The larger one for when they are further apart. Wet and dry sandpaper is wrapped round it - possibly 360 grit - I can't remember.
Here it is in action. The reason for removing the wood between the formers is simply to stop it showing through the tissue
after covering. If only the stringers show, it looks much neater.
Nothing to stop you making a set of home made blocks yourself, of course, or just rolling the wet and dry paper round a section of dowel of suitable diameter.
You could even just hack out the wood between the stringers with your modelling knife - it would not look very neat, but nobody is going to see after you have covered the model.
Final job was to open up the hole in the nose formers ready to accept a nose plug. The shape is not too critical, but it needs to be as large as you think you can get away with, so the
rubber will fit through it comfortably while stretch-winding. You will see how I modified an emery board by cutting it much thinner to use as a sanding aid.
Here is the final nose shape after a bit more sanding - at one point at the lower corner you can see daylight is beginning to show as I have rounded it off so much. We will worry about the
nose button in a later chapter.
To give you an idea of a target weight, my completed fuselage came out at 6 grams (using a postal scale accurate to 0.5 gram).
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