When I returned to the hobby some thirty years ago, I was bemused by the changes since I built my first Modelair Peanut. My thirst for knowledge took me to my friends’ workshops and just about every magazine I could get my hands on. To those experienced modellers, this was all pretty ho hum, but for me it was like finding Aladdin’ s cave. I fear that now, we“ experienced modellers” run the risk of becoming the“ Ho Hum” with regard to the basics and we risk overlooking the fact that thirsty new modellers are joining the hobby every day with little knowledge and under developed building skills. With the explosion in ARF, greater numbers are being exposed to our hobby, and a lot of these members are thinking,“ How do I build that myself” or“ How do I fix that?”
In recent discussion with our Editor Murray and President Barry who are always looking for copy for MFW,( an editor’ s lot is not always a happy one!), I suggested soliciting a series of“ How to” articles from the vast store of knowledge out there in our members’ experience. Not something copied and pasted from the internet, we can all do that anytime, but something personal and to the point applied to the various basic stages of aeromodelling. The obvious answer was...“ Put yer Money where yer Mouths is!“... so here we go. The following is not written to tell the experienced how to do it, nor is it meant to infer this is the best or only way. It is simply how I do it in my workshop that suits my circumstances. Even when talking to club members, I’ m amazed how many still ask me....“ how do you cut and shape foam like that?”, well, for what its worth, here we go.
FOAM CUTTING.
White polystyrene foam has been used around the modelling scene for many years, and is just another tool in our building armoury. Some love it, some hate it, especially wives who have just vacuumed the house and come home to find those little white beads spread throughout! Shaped correctly it serves as the basis for very accurate and strong wings and tail surfaces, and with use of just four templates, any shape and size of wing can be made.
Fig 1. Various cutting bows and power supply. The basic tools are a“ Hot Wire Bow” and a“ Power Source“, both of which are well covered in President Barry’ s recent articles. I made my original bow, still being used, bent from a piece of ¾ inch stainless pipe with the. 5mm Nichrome heating wire attached with insulators. The heating source is an old Ralta electric blanket transformer which can switch from 20 to 26 volts, I have no idea about the current, but it works! The thinner the cutting wire, the longer the cut or the denser the foam, more heat is required.
My first foray into wing cutting( 29 years ago!!) was under the guidance of John Clarke, an experienced local modeller and friend. I wanted a parallel chord plank wing. We made two identical aerofoil formers from formica and pinned them to each end of the block of foam already cut to the correct size. The formers were marked in steps one to ten so as we pulled the bow along say the top of the former, one person would call the numbers as the bow progressed and the other could then keep his end moving at the same speed and get a parallel cut. This system also works with a tapered wing, but usually because of a unsynchronised pulling or slight hook-ups etc the finish can leave a bit to be desired.