Scratchbuilding the Dove part 9

As I cut the right side of the cockpit to conform to the outlines present in the performed access hatch, I marked down through radial lines -- viewing these obliquely quickly denoted what areas needed additional attention with file and sandpaper.  Work went very fast using the ten pound model building foam

Cutting The Cockpit To Contour  

Working with knife, file and sanding blocks I cut the right side of the cockpit to conform to the outlines present in the preformed access hatch. Note that in picture #10 that, as this work progressed, I marked the work with a series of evenly spaced radial lines. Viewing the radial lines from dead ahead, dead astern, and obliquely quickly denoted those areas needing additional attention with file and sandpaper. This kind of work, using only hand tools, goes  very quickly.

You can see how the distinctive front facets of the cockpit are driven by the triangular shape originating at the leading edges of the access hatch - my Rosetta stone.

Once the cockpit had been roughed to contour, I addressed the sloppy fit between cockpit and access hatch:  Here I'm brushing on some  silicon grease to work as a 'mold release'.  The idea here is to apply some Spot-Lite to the top of the cockpit, where the hatch rests, and to quickly mash the hatch down making the filler conform to  the bottom and back shape of the access hatch.

How To 'Tighten Up' A Sloppy Fit  

Once the cockpit had been  roughed to contour, I addressed the rather large gapes between cockpit and access hatch. Photo #11 shows how silicon grease, applied to the underside of the access hatch piece with a brush, was used to work as a 'mold  release'. What I did, after treating the access hatch with the silicon, was to apply some Spot-Lite to the top of the cockpit, and to quickly mash the hatch down, making the filler conform to the bottom and back shape of the access hatch. This of course produced a very tight fit between the access hatch and the seating surface of the cockpit. Just as the filler began to harden I used the knife blade to cut off the filler that  extruded from the seam line.

No longer able to get a purchase under the seam I could only unseat the access hatch from the cockpit by pushing a pin through one of the alignment/securing holes through the bottom of the cockpit piece. Doing so pushed the access hatch off its seat where I could then grab it and remove it from the cockpit. This operation performed only after the filler had cured hard.

The very porous surface of the ten pound modeling foam had to be filled.   For this I chose Evercoat's Euro-Soft.  With its slower curing time and harder finish, this was the material of choice for the job.

Filling The Surface Of The Cockpit Master  

The very porous surface of the ten-pound modeling foam that made up the cockpit piece had to be filled. For this I chose Evercoat's Euro-Soft. With its slower curing time and harder finish, this was the material of choice for  the job. The best way to lay down this filler in this application is to catalyze some on the workbench and then transfer it with a finger to the work using the finger to rub the filler into the open cell surface of the canopy piece.

Care had to be taken to quickly unseat the access hatch off the canopy before the filler could harden - permanently bonding the removable access hatch to the canopy. That would be a major league boo-boo!
 

Once the Euro-Soft had hardened, it was worked with file and descending grades of sandpaper  until a smooth, unblemished surface had  been achieved.

The access hatch was re-attached to the cockpit once the filler had hardened. The entire piece was then worked with file and descending grades of  sandpaper until a smooth, unblemished surface had been achieved. More on that process later.

To Be Continued  

The next page of the DOVE article will deal further with the forming of the cockpit master: use of the marking fixture to lay down accurate radial checking lines, use of the contour gauge, use of the hull as a sanding fixture, and the initial steps in producing a rubber glove and GRP mother mold tool from which to produce a tough, thin walled production cockpit/access hatch  master.