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Nov 17, 2009, 01:51 PM
Alex Hoekstra's Avatar

Your cuttingtemplates are made of steel I think this wil cool down your cuttingwire and thats why it might stick. I always learned not to use any metal for cuttingtemplates
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Nov 17, 2009, 10:20 PM
It's a mere flesh wound!
Buddy Roos's Avatar
Nov 18, 2009, 02:33 PM
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Berrie's Avatar
@Alex, I know some people give the advice not use metal templates.

I have made templates out of 1mm carbonsteel, 1mm aluminium, 1mm wood and from the 1mm stuff used for covering desks etc. All these templates NEVER showed a "problem" I have now.

A few minutes ago I tested the 0.45mm thick stainless steel and a 0.5mm wire. Guess what? No problem!! i have a lovely piece of foamcore.

If I look closer to the samples I have cutted with the 0.45mm stainless steel templates I noticed the following:

1) 0.3mm wire: surface of the core is indeed better than cutting with 0.5mm. The 0.5mm surface is a bit rougher and has "melting holes".

2) The theoretical thickness of the core should be 6.4mm. (Zone 36, 123mm)
Both cores are 6.1mm thick before sanding of the surface.

3) The theoretical thickness of the core should be 3.9mm. (Zone 25, 76mm)
Both cores are 3.8mm thick before sanding of the surface.

4) So 2) and 3) 'proves' that there is no difference in thickness of the core when you use a 0.3mm or 0.5mm cuttingwire. (At least, according to what I did now. Someone else might have other experience)

**We will make new templates with a minimum thickness of 1mm. The ramps for the cuttingthread for the uppersurface of the foil needs to be a bit less steep.**

Below a picture, diffucult to show the differences between the surface quality. The above foamcore is cutted with the 0.5mm wire. Other one cut with 0.3mm wire.

p.s. Almost forgotten; The thin trailing edge of the core cutted with the 0.5mm wire was melted down on the lower foambed wile cutting the uppersurface. I needed to use a knife to free the core. But thats not a problem, just a remark.

Last edited by Berrie; Nov 18, 2009 at 03:56 PM.
Nov 21, 2009, 11:14 AM
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Berrie's Avatar

More foamcutting stuff, exercises for the mini Zone.

Alex is right. Metal template do cool the foam, or wire, during cutting. Let me explain a few things. I got a PM with the remark that it is possible to cut cores with a much better surface quality. That's interesting, because I've build a several planes cutting the cores the same way. I use to cut with a sort of "light my wire" style. I use to cut with a real hot hotwire cutter. The key for better surface quality should be in cutting with as less heat as possible. A cuttingspeed of 5mm each second should be the mark.

I couldn't resist and did a few tests. I collected some pieces foam, took a dive in the cabinet for 1mm aluminium templates and start testing. The thinnest availeble wire for me is still the 0.3mm one. So all the cuts are made with this wire. Normally I set my adjustable powersupply ready with a setting, press the button and the wire starts to cut. Not this time. I turned the potentiometer to zero and switched the powersupply on. Now I "opened" the powersupply slowly till the wire starts to cut with the desired speed.

As you can see on the picture below, it didn't work:

Altough the 1mm alumium templates are very slippery, the cutting was very ribbed. In my opinion the following happened:

You need heat to cut. Let's call that: Heatinput. Heatinput is nothing else than electic energy (V*I*time(s)) distributed over some distance

Cutting the rooth cord and tip cord happens in the same time. But the rooth is bigger than the tip, so the roothcord takes the less heatinput.

In fact, the heatinput at the root is so critical low, that the aluminium template absorbed to much heat. A small edge of foam doesn't melt. It is more or less teared apart. The terings make the ribbing. See also the close up. You see some pieces of foam.

The tipcord get's a bit higher heatinput. Just enough to cut the way you want. But again, it's critical. You can see some "glassy" edge.

If the above is more or less true, an expirement with formica templates is worth trying. As you can see, cutting with low speed/cold as possible wire, gives no problem! The formica don't absorbe the heat of the wire.

I will make formica templates for one mini Zone panel. Time consuming, hoping it makes sense.......
Last edited by Berrie; Nov 21, 2009 at 11:19 AM.
Nov 21, 2009, 11:47 AM
Registered User
When we were learning how to cut foam cores 20 years ago we found that templates made from either 1/8" or 1/4" phenolic stock (available at some electrical supply houses) was a good choice because it wouldn't cool down the wire. I don't remember where we got it but there is a teflon tape that we stuck to the surface of the template that gave the wire a VERY smooth surface to run on. (It's thin enough not to affect the airfoil) Phenolic isn't as hard as steel but it's a hard material which makes it very hard to get an accurate airfoil. I found someone that could laser cut plywood templates, (more accurate than trying to make the phenolic ones by hand) then added the teflon tape which seemed to work pretty well. If there is a source now for laser cut plywood templates I would try that and get the teflon tape.

just my .02
Nov 22, 2009, 09:45 AM
Registered User
Pook's Avatar
Thanks for those photos Berrie...most informative!

I'm hopeing to be cutting some wings in the next few weeks so every bit of info I can get now the better
Dec 05, 2009, 02:27 PM
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Berrie's Avatar

An update

most of the past time is spent with making the templates from formica:

With those new templates I have cut the cores:

The cores need to be treaded. I will try to rub of the hairs with my fingers, after that some light sanding. The leading edge must also be sanded in shape.

The wing is very thin....... This picture is from the tip cores.

Dec 07, 2009, 04:48 AM
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Berrie's Avatar
As Gerald mentioned in post #1 he has got many requests for a 1mtr Zone.

Is anyone else already building one? If so, can you please show some results and tell us about the lay-up, weights, set up etc. I'm just curious...

@ Gerald: the remark about the tailgroup in post #1 is for the aspect ratio 9.

Will it also work for the aspect ratio 8?
Last edited by Berrie; Dec 07, 2009 at 06:04 AM.
Dec 07, 2009, 10:31 AM
Registered User

It will work. There was about that much margin built in. Just don't fly it with a VERY rearwards CG as that could put the horizontal out of its low drag range. A somewhat forwards CG is fine. Actually I recommend setting up the plane with the CG perhaps a little farther forward than most use, based on a dive test. I moved my CG progressively forward on my Zone this past season and have found I prefer it in the forwards position. It is generally more forgiving, easier to keep flying efficiently. For those concerned with air reading with a more forward CG - all DLGs read air quite well, regardless of CG. Zones read air better than most.

Or you could increase the tail sizes a touch if you want instead of the 2/3 Zone 2P size, or increase the tailboom length slightly (about enough to keep the trailing edge separation the same as before).

What we need is someone to do a practical test of launching and handling. I tend to prefer that in the end, to modeling.

Dec 07, 2009, 02:31 PM
Registered User
I doubt many are building this plane. Most are probably daunted by the thin wing, and the low weight. I got a lot of requests for a design, but not as much interest once it was done.

Dec 07, 2009, 02:43 PM
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Berrie's Avatar
Originally Posted by G_T
Most are probably daunted by the thin wing, and the low weight. I got a lot of requests for a design, but not as much interest once it was done.
Oow boy, here I go (again).....

Now we are talking about weight (I will try to let this list grow during the build of the testprototype to see what can made better for the final plane):

The foam cores before sanding: 17.4 gram
Spar caps (with 10mm extra length): 5.9 gram

115 gram - weights above makes 91.7 gram for the rest

Such a list is "killing""......

btw, my gain is about 50 gram for this wing. I have now idea how "normal" that is.
Last edited by Berrie; Dec 07, 2009 at 03:33 PM.
Dec 07, 2009, 08:55 PM
Registered User
Originally Posted by G_T
I doubt many are building this plane. Most are probably daunted by the thin wing, and the low weight. I got a lot of requests for a design, but not as much interest once it was done.

I'll be building something 1.2M but I'm thinking the Edge foils might be better for me. So I'll wait, sorry but its your fault for coming up with more/better. LOL

Dec 08, 2009, 03:26 AM
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Berrie's Avatar
Originally Posted by The Tellurian
I'll be building something 1.2M but I'm thinking the Edge foils might be better for me.
Mmm, I consider building a new full size as well. If I had to make the choice for the foils right now, I go for the Edge foils.

If Gerald can design a mini wing with final Edge foils I would like to try a test wing too (roothcord also 169mm)
Last edited by Berrie; Dec 08, 2009 at 04:15 AM.
Dec 09, 2009, 04:55 PM
Registered User
As you all know, the Edge foils are still under design. I'm hoping to have time to devote to them this weekend, but not likely before then. I have some progress since I posted but mostly with respect to examining characteristics of some alternative tips to see what to try next. What I may end up with in the end is a very small increase in drag for a very large improvement in transition point behavior.

One can use the Edge series as currently published and it will mostly work very well, just it will lose its stellar performance faster than it should in rough air, though it will still likely work pretty well. Pretty much any Zone design could have the Edge foils swapped in.

Dec 25, 2009, 09:08 AM
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Berrie's Avatar

Merry Christmas!!

First part of the wing came out of the bag this afternoon. I like the weight.

Flaperons need to be cut out and a simple tape hinge must be applied.

Next wingpart will follow soon.

Last edited by Berrie; Dec 25, 2009 at 09:21 AM.

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