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 .