Need help with hotwiring foam wings

[javachip89]

Hi! Can anyone teach me how to build a hotwire and how to hotwire foam wings? I was wondering which airfoil to use also. I'm a newbie at this..

[viper1990]

hi there,

Its hard to teach over the internet/forum,it'll be easier to teach in person,nevertheless, i just did a mini demostration and hope its easy to visualise,(see pictures below)

My suggestion is go take some waste foam and go practise cutting them with hotwire. Just take any retangular,triangle or anyshape you want and try cutting them out into solid blocks before venturing into airfoil shapes. Play around with the hotwire, the temperature of the wire, the amount of force you need to pull the wire through the foam. Need some craftman skills to cut something out nice the first time! I screw up plenty of wings when i first started hotwiring but after a while it got easier.

For the airfoil, you'll have to do your own research to find out which airfoil best suits the intended application. For example ,flying wings you'll want to use Mh60 airfoils, Sailplanes will be the SD7032 , and many many thousands of airfoils to name. Trust me, i only use up to 20 of them until now.

I've written a mini guide on how to use the hotwire over here. Take a look!

http://www.daddyhobby.com/forum/showthread.php?t=55993

[edmond22]

The slightly more overboard alternative

You can also try fabricating a CNC cutter if you are in for the long run in this hobby.

This is an old machine I build a long time ago, still working great in cutting out that odd projects I have from time to time. Cost of setup, less than a k. Check the video of the machine at work below.



I based the build off this great guide here http://www.8linx.com/cnc/cnc.htm, A complete guide to building a inexpensive CNC cutter. See his build below, very nice.

[Deedubya]

Hi,
Great tutorial Viper.
I might add that there are two good books on the subject: Building with Foam by Keith Sparks and Radio Control foam Modeling by David Thomas. I think the Thomas book is a bit better but both cover all the basics and are very usefull.
Also I might suggest downloading an airfoil template program. I use Profili ( http://www.profili2.com/). There is a free version but the pay version (15 euros I think, the developer is Italian and takes PaypaL) is really worth it. He offers good support-i.e. answers e-mails readily and the program is really easy to use- I mean if a techno-phobe like me can get it to work...
Print out templates with wash-out built in- to me that's pretty neat. Can also use for built up wings. I've used it quite a bit for both.

A CNC cutter? Man that would be sweet. But it might be pushing it with the missus. Maybe I'll work on that after I convince her I need some serious vacuum bagging equipment...

[viper1990]

Thanks alot, yes i'm also using profili to get my airfoils printed out pretty neat software. But i didn't pay for it, but i still manage to print out the airfoils using printscreen method! haha.

As for the CNC hotwiring machine, thats insane man.. pretty cool to have one at home. Unfortunately my parents would kill me for taking up alot of space in the house! haha..

[javachip89]

Hello! I've been searching alot about airfoils and stuff, but i'm a little lost as to how i can print out the airfoil and use it as a template. Where do i look for the pictures of airfoils?

[joe yap]

You can print out the patterns directly from Profili, or you can export DXF files to Autocad.

[javachip89]

What i cant do is to get it to be big enough to cut out as a template.

[viper1990]

Hi javachip89

Do you mean that the airfoil you wanted to print exceed the size of the A4 paper? In that case the profili program enables you to print the airfoil in parts, you will have to cut out the 2 pieces and glue them together to form one big airfoil template.

I recommend you to download profili as it contains a tons of airfoil data in them,everything you need can be found in there.

[javachip89]

hmmm but u have to pay for it right?

[viper1990]

Its a freeware by it's own. But to unlock more features like printing you'll have to pay for it.