MFW June 2013 - Page 5

OK, agreed, a “drone” might be able to deliver a modest payload, maybe, but ask yourself, and you know, what is the chance of taking a new model full of technology, out for it’s maiden flight and it all works perfectly on day one, on arguably what is a complex and risky mission? Never mind of course, that you have managed to keep all your preparations away from other curious and prying minds and eyes No, I strongly believe the KISS principle will be the core of the next successful crazy attack. Yes, sure, “Drones” can do bad things in the right hands, but so can some sacks of fertilizer, trucks and fireworks. Let’s ban all this deadly baby-killing stuff! The next topic is one I learnt about 50 years ago from an old hand, and apologies if you know about it, but I find that few do. If you're looking for a effective, cheap, relatively safe, method for removing rust give electrolytic rust removal a try. What? It’s actually very simple and won't damage the underlying material. It consists of submerging the rusty metal part in an electrically conducting solution of washing soda The positive lead from an 12 volt battery charger is connected to a steel electrode and the negative lead is connected to the piece to be cleaned. A bit of rebar or an old tin can is ideal as the electrode. After a few hours the rust has been removed, the process does not damage the base metal in any way, it only removes the rust. Of course it does nothing to improve the finish of the metal under the rust so any pitting on the metal will remain, just the rust will be removed from it. The cleaning solution will last almost indefinitely, but gets to look pretty nasty and dirty. You only need to add water to replace that lost by electrolysis and evaporation, if you want, but washing soda is so cheap I always make a fresh lot. Other alkalis will work too, but most are more expensive and/or more hazardous. A few safety precautions are required. Please think, and take care ! • The cleaning solution is alkaline and will irritate your skin and eyes. You should use eye protection and rubber gloves when working with this and wash up any spills with fresh water • Make sure the battery charger can’t get water splashed on it. A cheap RCD is great insurance and is strongly recommended. • The leads from the charger are relatively safe but it is still possible to get a shock if you put your hands in the cleaning solution or touch the electrodes while the power is on. • The process generates hydrogen and oxygen. If you get it just right, a spark might cause a gas explosion, So, work in a ventilated place and avoid shorting out or sparking from the leads. Just like normal battery charging. But I do this outside to avoid any problems, and I’d suggest you do the same. Next topic. Let me be blunt, I hate planking, no, not the new craze of laying out here and there, if you don’t know what I mean, see en.wikipedia.org/wiki/Planking_(fad) and for proof that Darwin’s Law is true ! No I mean the old method of cutting increasingly smaller and more precise balsa strips to cover a fuselage turtle-deck or similar. So, I cook it and bend it! Or more precisely, I steam it. Some years ago, I learnt at a woodworking seminar, just how amazingly flexible wood becomes by heating it. It can be done with dry heat, but steaming tends to give better results. About 60 minutes of steaming per inch of timber makes it like sphagetti. My solution can be seen below. It’s an 800mm ply box held together with brass screws, a removable wood plug at each end and a hole to introduce steam at one end. An old whistling kettle on a camping stove provides the steam. Balsa, ply or veneer in there for about 30 minutes becomes very soft and flexible for about 10 minutes after it is removed. So you have to work quickly, and be careful of the steam, it takes surprisingly little to burn bare skin ! I know this, because ? Here’s a couple of finished examples. Right is 8 layers of veneer bent around a fin/rudder template and glued with ordinary PVA. Picture below shows how a piece of 1/16 balsa can be easily rolled around an ordinary pencil.