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Old Dec 12, 2014, 08:46 AM
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United States, AL, Daphne
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I Need Templates

I posted this in the Classifieds but figured I'd put it here as well:

Juzwuz is busy until some time next year but I'd like to get some laser cut templates so I can start cutting cores. PM me for details of what I need then you can give me a price.

Thanks
Trey
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Old Dec 12, 2014, 04:13 PM
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United States, AL, Daphne
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I'm looking at G_T's SynerJ foil and Drela's AG foils. I can't seem to find the thickness of Drela's AG40, AG41, AG42 and AG43. Anyone know the thicknesses?

Thanks
Trey
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Old Dec 12, 2014, 06:22 PM
Little Red Plane
United States, NC, Greenville
Joined Dec 2012
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Profili has a template tool. Have you looked at it?
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Old Dec 12, 2014, 06:58 PM
Red Merle ALES
Curtis Suter's Avatar
United States, Mt, Helena
Joined Apr 2002
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If you take this free program:
http://www.xflr5.com/xflr5.htm

And these airfoils
http://www.charlesriverrc.org/articl...t-airfoils.htm

....and these airfoils
http://m-selig.ae.illinois.edu/ads/coord_database.html

That should keep you busy.

When I get home if you don't have the answers I can go to Profili or XFLR5 I can get you the specific info you requested.

Curtis
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Old Dec 13, 2014, 09:53 AM
Red Merle ALES
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United States, Mt, Helena
Joined Apr 2002
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Quote:
Originally Posted by Trey4U View Post
I'm looking at G_T's SynerJ foil and Drela's AG foils. I can't seem to find the thickness of Drela's AG40, AG41, AG42 and AG43. Anyone know the thicknesses?

Thanks
Trey
AG40-02f
Max Thickness 8.00% at 27.8% of the chord
Max Camber 2.04% at 39.1% of the chord

AG41-02f
Max Thickness 7.72% at 26.4% of the chord
Max Camber 2.01% at 37.7% of the chord

AG42-02f
Max Thickness 7.31% at 25.0% of the chord
Max Camber 1.98% at 34.9% of the chord

AG43-02f
Max Thickness 6.54% at 22.2% of the chord
Max Camber 1.84% at 34.9% of the chord
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Old Dec 13, 2014, 01:46 PM
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Jim.Thompson's Avatar
Australia, NSW, Bellingen
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Trey,
This tip may be superfluous, but will offer it in case it is not obvious.
When you get the templates cut, make sure they are cut with proper hot wire cutting entry and exit ramps and not just a sharp turn where the chord line intersects the airfoil shape.
This discovery was a huge breakthrough in hot wire cutting for me. No sanding at the trailing edge required, and only a slight amount required at the leading edge.
Further details provided if necessary.
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Old Dec 13, 2014, 02:32 PM
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Quote:
Originally Posted by Curtis Suter View Post
AG40-02f
Max Thickness 8.00% at 27.8% of the chord
Max Camber 2.04% at 39.1% of the chord

AG41-02f
Max Thickness 7.72% at 26.4% of the chord
Max Camber 2.01% at 37.7% of the chord

AG42-02f
Max Thickness 7.31% at 25.0% of the chord
Max Camber 1.98% at 34.9% of the chord

AG43-02f
Max Thickness 6.54% at 22.2% of the chord
Max Camber 1.84% at 34.9% of the chord
Thanks! I got XFLR5 but couldn't figure out how to import Drela's coordinates. Got Profili which had some of Drela's foils but not the ones I wanted. Couldn't figure out how to import coordinates there either. Thanks again.

Quote:
Originally Posted by Jim.Thompson View Post
Trey,
This tip may be superfluous, but will offer it in case it is not obvious.
When you get the templates cut, make sure they are cut with proper hot wire cutting entry and exit ramps and not just a sharp turn where the chord line intersects the airfoil shape.
This discovery was a huge breakthrough in hot wire cutting for me. No sanding at the trailing edge required, and only a slight amount required at the leading edge.
Further details provided if necessary.
Yep, learned that the hard way over 20 years ago.

Trey
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Old Dec 13, 2014, 02:48 PM
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Quote:
Originally Posted by Trey4U View Post
...................
Yep, learned that the hard way over 20 years ago.
Trey
Very good!
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Old Dec 14, 2014, 11:09 PM
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Quote:
Originally Posted by Jim.Thompson View Post
Trey,
This tip may be superfluous, but will offer it in case it is not obvious.
When you get the templates cut, make sure they are cut with proper hot wire cutting entry and exit ramps and not just a sharp turn where the chord line intersects the airfoil shape.
. No sanding at the trailing edge required, and only a slight amount required at the leading edge.
Further details provided if necessary.
What do you mean by "proper hot wire cutting entry and exit ramps". I know there's a ramp or lip at the leading edge to start and aat trailing edge to exit, but a picture or explanation would really help. Do you use 2-piece airfoils, 1 for bottom, and the top that rests on the bottom one for the toptop, or a 1-piece airfoil cut out, and held on with tacks, etc.? Thanks.
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Old Dec 14, 2014, 11:31 PM
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Ok FF, I will explain. I might also get time to do a drawing tonight. I could post that later.
But here goes:
Leading edge shape when drawn ex Profili2 or similar, will show a sharp change of direction from the horizontal chord line to the curve of the leading edge of the airfoil. In both directions of course. Up for the top and down for the bottom.
This can create a problem with getting the wire to start moving through the foam.
A simple small radius curve of lets say, 6 - 10 mm (depending upon the size of the templates concerned) at this point will alleviate this problem. The curve will intersect the chord line and the beginning of the airfoil shape. This leaves a very small protusion that will be sanded off later.
The same curve is made on both top and bottom templates. Yes, I use separate top and bottom templates. I did try using a bottom template and an airfoil shaped one that sat on top for the top cut, but abandoned it after lots of problems with the wire going between the two instead of up and over for the top cut. Besides, it did not allow for the curve, mentioned above.

The Trailing Edge;
This is simple. The line of the last 1/3 of the airfoil is continued on instead of transitioning to the horizontal chord line. No sharp change of direction, which means that there is no problems created due to the inevitable wire lag. Done this way, it results in cores that need no sanding at the TE.

I hope that is reasonably clear.
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Old Dec 15, 2014, 07:02 AM
Red Merle ALES
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This is how I do it.
http://www.rcgroups.com/forums/showp...2&postcount=21

Curtis
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Old Dec 15, 2014, 12:10 PM
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The exit ramps appear to be on the chord line Curtis, at least that is the case in the top template, view # 137.
That will involved a change in direction of the wire at the templates. The wire lag will mean that it will not follow faithfully at the middle and so create some slight thickening there.
See my description above re how and why I avoid this.
I see that you have provided a "ramp" entry at the LE though.
It seems I will have to draw that diagram or diagrams.
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Old Dec 15, 2014, 12:34 PM
Red Merle ALES
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There is a 1/4" of foam at the trailing edge (TE) that is not used. The vertical line on the template at the trailing edge is the actual end of the wings TE. This way when the wing is done and I'm transporting the wings in the foam cores there is a 1/4" of foam to protect the fragile trailing edges.

I also like the foam core to be a smidgen shorter than the actual chord of the wing so that once bagged the top and bottom skins are touching one another.

Curtis

PS By the way, I measure with eyeballs and not a micrometer. In other words I'm more of what works than what the exact measurements are supposed to be.
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Old Dec 15, 2014, 12:57 PM
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I appreciate that this is a bit hard to communicate without pictures.
Maybe this diagram will clarify.
Please observe the trailing edge part of the template. There is no change of direction to create distortion due to the inevitable wire lag.
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Old Dec 15, 2014, 01:20 PM
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No ramps.

This diagram is one of a template ex Profili2 without entry and exit ramps. Note: the line at the trailing edge does change direction and so creating thickening effect around the middle of the panel at the TE.
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