G'day from the Goldfields.

Damn these monthly deadlines come around fast! I don't have a lot to report from the club this month, as it has been pretty much business as usual, with little news to report. However, in late breaking news, the Delta of John (speed freak) Bates has come to grief.

As I was away on the day, I can only report second hand, that it died in a manner unbefitting for a model that has given much entertainment. Apparently a plug failure at an inopportune moment saw it lose power and come down in the trees damaging it irreparably. Any doubt that it was irreparable was solved by John chucking the a match into it's remains, which was probably the best option anyway.

One downside of flying in the Goldfields is our cursed red dirt. Even a minor bingle gives a model a film of red dust that is next to impossible to eliminate, forever ruining the look of you models. I always advocate crashing on the concrete as it may be less forgiving, but a whole lot cleaner. In a major bingle, stray gold nuggets in the soil may also end up lodged in hidden areas causing balance problems for the un-initiated. Damn heavy stuff that gold. That is all I have of club relevance this month. The rest of this article continues the building of the Caribou saga. Those of you who have better things to do may wish to change the channel!

It's rare during the construction of a model to discover a technique or product that works way beyond expectations. I have been lucky to stumble onto three such examples during the construction of my scratch built Caribou.

The first is a lightweight wood filler available from most hardware stores and made by Selleys. Called Spak Filla Rapid, it is perfect filler to use in a number of instances. It is great for forming fillets a e base of rudders and wing roots as it is easy to shape when wet and when dry is extremely easy to sand to a finished shape. It is extremely light and when applied to large area of balsa such as a balsa sheeted foam cores when sanded off, it fills the wood grain and hardens the balsa to give a great surface to finish, either by priming and painting or covering in a paintable covering such as Oz Cover.

Oz Cover is the second of the finishing revelations that I have for you. An Australian product it is easier to use than the usual plastic coverings. For one it does not have that incredibly annoying backing to peel off. Just cut it to size and apply by the usual methods. The other large advantage is its tolerance to heat. In areas that prove difficult to shrink, just turn up the heat until you get the result that you want. To date, I have not had an incidence where I have melted a hole in a surface or had an edge melt back due to over enthusiastic use of the iron, both regular occurrences when I have used other shrink films. Being paintable with enamel paints is a huge bonus to a builder of off scale aircraft as I am able to use my favourite paints - epoxy enamel spray packs by Wattl Killrust. Although ver slow drying this is a superb paint, available in a few useful colours, including aluminium. Being an epoxy enamel it is very stable and durable.

The last of my revelations is a technique. I decided to try the brown paper and PVA glue method of covering the foam fuselage of the Caribou. I had read about the technique some time ago in edition 163 of Airborne magazine where it was used to cover a foam C130 electric model.

Fortunately I did not re-read the article before starting and blundered along on my own and came up a few accidental refinements. The first was the glue to water ratio. I mixed the two at 50/50 and got fantastic results at a cheaper rate that the 70/30 mix recommended by the author. I also applied my brown in strips, some as large as 600x50mm, overlapping each strip by 50% to get a hard shell two layers thick. Starting at the tail and moving forward applying vertical strips 20 mm wide in areas of large curvature and progressing to strips 50mm wide in flatter areas. Once the section from the tail to the rear of the wing was covered, by doing first the left and then right sides from the top centre line down, overlapping by 3mm along the top centre line. I then used the 600x50mm strips to cover from the rear of the nose section to the rear of the wing. Starting underneath the model and overlapping 50% on each strip quickly covering the centre section.

To cover the nose section, I started on the top rear and worked my way forward using smaller strips and squares to give the nose a total of 3 layers for extra strength.

When applied, the brown paper has the occasional wrinkles that will worry you. Smooth them out as best you can gently with a damp cloth then ignore them. As the brown paper dries, it shrinks and flattens like crazy leaving a very light weight smooth and strong surface. Using strips applied in similar size and direction to the panelling on the full size aircraft leaves behind a faint impression of the panelling.

I did not follow the author's method of applying the paper. The associated pre-wetting of the foam with glue, then wetting one side of the paper with glue, then applying the paper, then wetting the other side. All unnecessary and time consuming. All that is needed is to mix up your glue in a suitable container, dunk your bits of paper in and using you fingers squeegy off the excess glue by drawing the strips between your fingers. Position the pieces onto the foam and then gently dab dry off any excess glue with a clean cloth. A bucket of water to continually wash the glue off your fingers as you work may be an advantage. Pre-cutting lots of paper is also advisable. Also, only cover sections left to right, to avoid making a banana off the finished model as the paper does shrink considerably.

The shrinkage of the paper does also have the effect of compressing the foam a little, so expect some depressions that may need filling in curved area, or areas over underlying structures. Using shorter strips or squares may reduce this problem.

The end result of brown paper/PVA is a lightweight hard shell not unlike the pre-stressed skin on real aircraft. It is also cheap and can be applied to any shape. As polystyrene is very easy to shape and is super lightweight, there is no limit to the possibilities for future construction.

My next article should discuss the manufacture of fibreglass cowling, another technique I have yet to master. To date, I have only carved a foam replica of the finished article and used the Selley's rapid Spak filla to correct imperfections to surface an shape. It is important if using filler to finish a polystyrene model of the required article, that the entire surface of the article is coated with filler and then sanded off. This will give a consistent hardness to the total surface area of the article and will help to produce a more accurate final product free of surface depressions.

I feel I've used up more than my fair share of your precious time, so I'll leave you to it, whatever that may be !

Tim Bailye

GAM 08 90913714

Web Page : kalnet.com.au/gam