Build your first flying scale Jet - Chapter 8 - Cockpit and canopy
Before we can mould a canopy we need to carve a canopy block. Here the side profile has been cut from the plan and stuck to a suitable balsa block
using a restickable glue stick. As with the spine, note a bit extra is left at the bottom to account for the curved upper fuselage.
Rough shaping has been carried out using the same knife used for the spine.
The final upper profile was achieved by sanding on some emery paper glued to a perspex offcut.
To get the plan view correct, the shape was cut from the plan and glued to the bottom of the block.
To make it easier to check the fit on the fuselage, I sanded in a concave section to the base of the canopy block
Now the canopy block can be tested for fit on the fuselage
The paper patterns were removed, and the top rounded off to the correct cross section.
Check continuously at the back to match the shape to the fuselage spine.
To help get the front of the canopy block the right shape, a line was drawn on at the break where the canopy opens on the real aircraft.
This allows the top of the flat front windscreen to be positioned correctly. Shaping is just about complete in this photo.
No finishing materials are used on the canopy block - it is just bare balsa. If you were vac-forming a canopy, rather than plunge moulding,
further steps would be needed to give the canopy plug a smooth enough surface.
Before moulding, a small block was added to the rear of the plug to avoid local thinning of the plastic at that point, and a piece of 1/8"
balsa sheet glued to the bottom.
Here the lower sheet has been carefully sanded to maintain the contours of the canopy plug and a length of hardwood dowel glued into a drilled hole in the bottom of the block.
Behind you can see my first attempt at the female part of the mould - basically a suitable aperture cut in a sheet of 3/16" balsa, with rounded edges.
After pulling a couple of test canopies it became apparent that I had left too big a gap between the plug and the hole at the rear of the canopy, and so
the plastic was not following the contours of the plug properly. Hence the bodge shown here to avoid having to make a new female form (actually I had
run out of suitable thick balsa sheet). A gap of about 1/16" would be ideal I think.
A piece of suitable plastic sheet is pinned across the female mould like this.
Heat under the grille, and when the sheet is hot enough, push the plug through the hole to this depth.
For more details of the process, refer to this article.
Here is the view from the other side with the plug removed.
One canopy has been trimmed, the other kept as a spare. The plug is inserted into the canopy while you trim it, using the join between the block
and the bottom 3mm plate as a cutting guide.
It's now time to add a few rudimentary cockpit details, including this bit which sits at the rear and stops you seeing right
through the rear two windows of the canopy.
After carving and sanding the outside shape, I dug out the inside a bit to save weight.
I freely admit to being rubbish at making pilots, and always use a commercially available option if there is one. Unfortunately there
didn't seem to be a suitable jet fighter pilot to buy, so I had to resort to butchering an innocent block of soft balsa.
Completed cockpit details ready for painting - the seat was made from scraps of sheet balsa. All the parts have had a couple of coats of
sanding sealer applied.
Note I have used a thin marker pen to draw on
the canopy poisition - this gives a guide to which area needs painting before attaching it.
Here are the results after painting. The pilot is pretty poor, but at least it will look like someone is at the controls when I get it flying.
The canopy is glued into position with water based "Formula 560" canopy glue, which has the advantage of drying clear. Note the back edge of the canopy
sits just over the front of the spine block.
When dry, paper fairings can be added to blend the spine and canopy into the fuselage contours. If you look at photos of real Thunderstreaks,
this smooth transition between spine, canopy and fuselage is very obvious, and these paper fairings add considerably to the realism of the model.
They are also easy to do. I used some glossy paper that dropped through our letterbox advertising something or over.
The strips are cut out and curved over the
edge of a table to preshape before application. They are then stuck on with canopy glue again. The water based glue softens
the paper somewhat and helps it conform to the desired shape.
Here you see the other side, with all three pieces added.
And here is the finished fuselage ready for painting.
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