What's It all About ???

This page is all about the building and flying of radio controlled model aircraft. It's a highly diversified hobby that takes in as many skills as you like to use. Everything from electronics to carpentry, to painting, to drawing and designing with a little bit of metal work thrown in. Some builders even go into doing their own machining, pattern designing, fibre glassing, moulding and engine design. You can use electric motors, 2 stroke or 4 stroke internal combustion engines or even minature turbine (jet) engines for power. My own models use 2 and 4 stroke internal combustion engines and range in size from about a metre in wingspan to well over 3 metres from tip to tip!

Saturday, October 27, 2012

In The "Good Old Days"

As readers will know one of my current projects is a Lanzo Bomber and, as it a classic old timer design, I've tried to build it as much as possible by traditional methods and with traditional materials - SO - that just had to include covering it with tissue instead of one of the modern iron one materials.

Tissue?? - yep - and a good old traditional shrinking dope. Now the older readers probably know what the hell I'm talking about but younger modellers might think I've lost a marble or two. So - for their information and amusement here is how we used to do it in the "good old days"

I've added this comment because some one commented on the dangers of using chemicals: 

Model aircraft dope contains dangerous chemicals which are both toxic and volatile! Do not use dope without adequate ventilation and preferably with a fume mask. Do not smoke or use the product near an open flame. Children should only use this product under Adult supervision

First job is to select the grade of tissue - it's usually available in light -medium and heavy grades. For this job I chose SILKSPAN medium grade. Then for the typical covering job you need to cut out 4 panels - that is top and bottom on both sides. Of course for things like the fin and rudder you only need 2 and for a big wing you might use 8 or more.

You also need a couple of brushes, a can of dope and preferably a bottle or can of Acetone for thinning and cleaning your brushes after use.

I apply the first panel buy brushing on unthinned dope around the edges of the panel and then applying the tissue over the panel before the dope has dried.I brush a second coat over the edges of the tissue to ensure it is firmly fixed all around.

Trim the tissue after the dope has dried and cut slits every cm or so around curved edges - tissue does not have the same 'stretch to conform' properties as the iron on covering

When everything is trimmed I use a water spray to lightly soak all the tissue. I wipe off excess water and leave the tissue to dry thoroughly - this step pre shrinks the tissue so you get a nice tight finish when you dope the whole structure.

I apply an overall coat of dope - thinned by 40% with acetone over the whole structure. For light weight tissue this is sufficient but for medium 2 coats and some times 3 for the heavy weight.

And when every thing is dry this is the result. Remember that tissue is translucent and any marks that would normally be covered by heat shrink film will show through the tissue. Some Hobby shops might be able to sell you coloured tissue or if not you can colour the thinned coats of dope with food dyes. Remember to use a fuel proofer if you are using an IC engine.