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Sep 23, 2021, 07:41 PM
Duane, LSF IV
Wazmo's Avatar
Well, it's not exactly a NACA 63012A. Here's an overlay of NACA 63012A, scaled up so truncating the airfoil at 12 inch chord yields a 1/16 inch (1.6mm) thick trailing edge, on the root airfoil shown on the plans. I think the best approach at this point will be for me just to trace the airfoils from the plans.

Name: NACA 63012A vs Chilli Wind plans.png
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Sep 23, 2021, 07:41 PM
TLAR Aviation
Harry D's Avatar
Hi Jeff.

I used Compufoil to make a few sketches that might help you with this. Inch units, because that's what the original plan is in.

First off, I trial fitted a few standard airfoil files to the hand-drawn, side-of-the-boot one shown on the Outerzone plan. I ended up using a NACA0014-23 airfoil as a base, tweaked in Compufoil to give a 13.6% thickness and 1/16" trailing edge on all ribs. It fits pretty closely and cleans things up a bit.

Some assumptions:

- A rib spacing of 3", with an additional rib at 1.5" from the center of the wing (under the fuselage side).

- Constant 1.5" wide ailerons, per the plan; 1/4" wide LE and rear strips.

- As you requested in your similar query on the RCM&E forum (I assume that was you) I have shown two 1/4" square spars at the airfoil high points.

- I assumed you will be using 1/16" leading edge sheeting and capstrips, as shown on the rib layouts.

The attached PDF files show the basic wing plan with rib locations indicated, and a set of ribs. Both generated in Compufoil. These are on A1 and A2 size sheets, so you would have to tile print or get access to a large format printer.

Hope this helps. Please let me know if you would like anything done differently. It's easy to make changes with just a few clicks. Let me know about any goofs so I can fix them. If you want to have the ribs laser cut, I can let you have the CAD files.

Good luck with your project. Let us know how it turns out.

Sep 23, 2021, 11:31 PM
Registered User
I want to add that when printing profiles on paper, it is imperative to calibrate the printer. And make sure the dimensions of the printed rib match the dimensions of the rib drawing.
Sep 24, 2021, 05:01 AM
Registered User
Thread OP
Hi Guys
Thanks for all your help, much appreciated.

i think we expected the profile to be slightly thinner, comes from the 012 designation. Personally I wasn't too worried. They do say the Wind is a speedy ship anyway, this would just make it a little more so.
Don't know much about computer plotting, but I thought it would be easier working with a known section.
If it helps, I got the rib profiles scanned into a pdf file. I could easily send that to you.
Tracing sounds so old fashioned.
Let me know.

How you managed to do so much in a short time impresses me. What I wouldn't give to be that fluent.
You even included a rib at the fuz edge. Great idea which hadn't even occurred to me.
Did run into a small issue, probably more at my end.
On your pdf I set the zoom to 'actual size' and printed off a copy. Printed fine, except the overall length of the root rib came out at 11 3/8" (290mm) rather than the plan at 12" (305mm).
Quick calculate says changing the zoom ratio to 105% would do the trick, but I only appear to have the choice of 100% or 110%.
Your thoughts?

Did a google search for how to calibrate my printer (Canon Pixma iP1800) but found nothing apart from a note that some Canon printers cannot be calibrated.
Perhaps mine is one of them.
Cue hordes of posts saying 'yes you can'!
Any thoughts?

Thanks again

Sep 24, 2021, 10:22 AM
Registered User
Hi Jeff.
I am using the old way of building ribs. Not on the drawing board, but in Auto CAD. It looks something like the photo.
I have an HP Deskjet 2020 series printer. When printing to JPEG or PDF, I didn't find the calibration either. But when printing in Auto CAD, the calibration appears in "properties" and subsection "device and document". Probably because dimensional accuracy is required. I assume that your printer works like that as well.
Sep 24, 2021, 10:42 AM
TLAR Aviation
Harry D's Avatar
Jeff, I'm not sure what that problem with scaling is about. I test printed the root rib from the PDF file I posted on my laser printer and it came out at exactly 12". The only thing I can think of is that if you were printing on A4 paper (11.4" long) perhaps your printer is being too "smart" and thinking to itself, "Well, this guy asked for 100% scaling, but if I do that he won't get the whole thing so I'll make it just small enough to fit the page". A long shot, and I don't know if printers even do that kind of thing, but I can't think of any other reason for that wrong scaling. Printers do sometimes give scaling errors but in my experience not that badly. Do you have any legal size paper (8.5" x 14") you could try, if you haven't already?

The best thing for you to do, if you want to save a lot of hassles, is just go to a print shop and have them print the full A1 and A2 sheets. And while they're at it, print you a mirrored copy of the wing plan, for the left half. I gave up messing with tile printing and all that kind of thing long ago - it's just an exercise in frustration and the end result is never much good. Having a print shop do it properly is quick, easy, accurate, and inexpensive.

Good luck with this. I hope you find a solution that works for you.
Sep 25, 2021, 02:36 PM
Registered User
Thread OP
Hi Harry

Found a solution to the problem but it's a bit oddball. A post on the UK forum started the train of thought, so here it is:

When I open a pdf file, I get a dialog box with various options. One of these is 'save file'. Pretty obvious what that does. Another is 'Open File with Firefox' which is my default browser. Always used this one with no problem.
However someone on the other forum mentioned Acrobat DC, which is Adobe I believe.
Anyway, one of the other options was 'other' so I clicked on that and found a list that included Acrobat.
Opened the file with that and everything printed to proper size.
No idea why this was so, but I don't really care. I have a set of usable rib templates, so all I need to do now is to get building the damn thing.
This involves balsa and sharp knives. At last, something I know about, phew!
Couple of thoughts.
Guys on the other forum have been following my battle. Couple have expressed interest in your files so would you have any objection to me passing them on?
Also, someone suggested you send your files to Outerzone so they can include them as a supplement to the plan they already do.
Up to you, but it would get your fine work to a wider audience.
Meanwhile, many thanks for your help. It will be put to good use.
Sep 26, 2021, 10:37 AM
Registered User
There is a smaller version of the Chilli Wind called Chilli Breeze with 48 inch span.
Harry would you consider scaling down the ribs to make Chilli Breeze ribs?

Chilli Breeze is similar shape to Chilli Wind and was a free plan with RCME years ago. Quite popular design here in England. Construction is similar to the larger version and rib spacing is 2.25inch with aileron 1.25 inch wide. !/4 spars, 1/4 LE and 1/4 by 3/8 TE with 1/16th sheeting. Root rib 10.75 inch tip rib 7inch. wing shape is similar with angled tip rib. 11 ribs each half including common centre rib.
Sep 26, 2021, 11:09 AM
Registered User
Thread OP
Hi kdc

We are thinking along similar lines. Did wonder if Harry would be prepared to do the Breeze ribs as well, but since he's done so much work on the Wind, seemed it might be a bit of an imposition.
Anyway, now you've asked, I can lurk in the background and you'll get the blame if it ends in tears.
Just one thing to add.
The Breeze uses exactly the same wing section as the Wind, just a little smaller. In fact, rib no 5 on the Wind is almost a perfect match for the root rib on the Breeze.
I would suggest ignore the angled tip rib. Just adds extra complication. Same can be achieved by using a straight tip rib and some balsa block.
We'll see what Harry thinks

Sep 26, 2021, 04:40 PM
TLAR Aviation
Harry D's Avatar
Hi Jeff and kdc.

I've been following your Chilli Wind thread on the RCM&E forum (where I'm not a member but have been a regular lurker for years) and was about to post a respose there to the various questions and comments raised. But since you've asked here, I'll respond here to avoid saying the same things in two different places. You guys may want to post a link to this thread in the RCM&E forum in case anybody there wants to follow it.

First off: Jeff, I'm pleased to know you got your printer scaling issues resolved and can now go ahead with your build. The PDF files in Post #17 will work OK but because I hate the whole principle of tile printing plans so much, I spent a bit of time this morning reorganizing the rib layouts so that won't be necessary. See the attached revised PDF file, which has the balsa rib outlines only (not the whole airfoil section) and will fit on A4 sheets. (I sure wish we here in North America could get our metric act together and join the rest of the world, instead of perpetuating the mess we have now. But that's another subject.)

I've also attached a .DXF file of the rib outlines, in case anybody wants to laser cut them. DXF files can't be posted here as such, so I've changed the extension to TXT. Change it back to DXF to use.

Just a minor note here, which may be of interest to those of us using paper prints to cut parts (I still do that sometimes too). Forget glue sticks, double sided tape, and such. Cut the part templates around the outline, leaving a border all around (a few millimetres, doesn't really matter). Put the paper face down on a scrap surface, and mist on a VERY LIGHT dusting of 3M77 spray contact adhesive. Just one or two quick spritzes, from at least a foot or so away. Let this dry for AT LEAST TWO MINUTES - this is important. Then, press in place on the wood (or whatever) and cut/sand to shape. The paper template sticks firmly, but can be lifted off when desired with no problem and leaving no residue at all on the part. Very much like a Post-it note. Try it, you'll like it.

OK, to respond to a few of the issues raised on the other forum.

- I posted those PDF files in this open, public, RCG forum so anybody who wanted to could view and use them in any way they liked. Absolutely no problem at all for me if fellow modelers use, share, copy, modify, or do whatever they want to with them. That's what they're there for. And it's certainly not in any way "my design", as I think was mentioned somewhere. Jeff, feel free to post or send any of those files anywhere you like.

- I was thinking of sending these files (or something similar) to Outerzone. I've done that in the past with several projects, but have generally tried to submit a more complete plan that may be more useful to Steve and his users. Maybe I'll do that at some point in the future, when I have something better. He would be more than welcome to what's here now, though.

- Jeff, you were asking about a trial version of Compufoil. I see that one does seem to be available: You may care to look into that. I've been using Compufoil for over 25 years, and have found it to be superb in every way. Support is excellent. I also have Profili, which works OK, but I much prefer Compufoil - possibly just a personal thing.

About the Chilli Breeze (smaller version). I'd be happy to draw up a set of ribs for that. No "imposition" at all - I really enjoy playing around with this stuff. I don't have that plan, so just to be sure I'm doing it right, I'll sketch something up and you guys can take a look at it. One of the nicest things about doing this stuff on a computer is that it's so quick and easy to make changes (and fix mistakes). I'll get onto that later today.

Enough of my rambling (almost). Just a curiosity question. I don't know where Toronto came from as my location - I'm in Edmonton, and there IS a difference! Also, I found the phrase "...Toronto of all places" kind of interesting. Not a problem in any way, and no big deal at all, just a little odd.

To be continued...
Sep 26, 2021, 04:55 PM
Entropy is happening!
Jim.Thompson's Avatar


There is a free piece of software called Profile, which I understand has an inventory (library) of a collection of common sections.
For applications such as this, I assume it would serve the purpose adequately.
For small power planes, airfoils are not nearly as critical as, for example, choosing one for a high performance sailplane.

(I use Profili2, so I have yet to try Profile).

Sep 26, 2021, 10:41 PM
TLAR Aviation
Harry D's Avatar
Originally Posted by kdc.
There is a smaller version of the Chilli Wind called Chilli Breeze with 48 inch span.
Harry would you consider scaling down the ribs to make Chilli Breeze ribs?

No problem, quick and easy to do. But there's a discrepancy between the dimensions you quoted (11 ribs spaced at 2.25", giving 22.5" half span) and the stated 48" total span (24" half span). See attached plan sketch. I'm probably splitting hairs here and it doesn't really matter anyway, but I like to try and do things correctly if I can. Maybe I'm missing something such as a central spacer. Do you have an actual plan that would help me here? Once we've clarified this, I can finalize the ribs.
Sep 27, 2021, 04:34 AM
Registered User
Old school does work. I think.
Sep 27, 2021, 04:38 AM
Registered User
Thread OP
Hi Harry

While the rib profiles you posted were easily sufficient to build the ribs, the cutting templates are even better and perfect for purpose.
Thanks for that.
Now, the Chilli Breeze.
On my plan, half span measures at 23", which would make the span 46", not 48". My plan came from the magazine many years ago, and has somehow lost a page so I don't know if it has any tip blocks fitted.
Judging by the Wind, I would think not, but even so they are unlikely to be 1"wide, so I would take the 48" to be a typo.
Also, although the plan does not include intermediate ribs, it does show the wing plan with rib positions.
The quoted rib spacing of 2 1/4" is from the outboard edge of one rib to the inboard edge of the next.
So the true rib spacing, c/l to c/l should be 2 5/16". On 10 bays this works out at 23 1/8". Close enough to my measured span for all practical purposes.
On the Wind, you moved the two inboard ribs inward to match the fuz sides. On a model the size of the Breeze, not sure if it's worth it. However, if you do, the width of the former above the wing cut-out is 2 3/8".
As always, appreciate your help.

Sep 27, 2021, 11:04 AM
Registered User
As you all guessed I measure rib spacing between the 1/16th ribs so the slight variation in span.
Chilli Breeze half span measures 23and 7/8ths inch on my copy of the free plan from RCME. So 47.75 inch span. This is measure at TE. Tip wing rib slopes so tip rib spacing is 3inch at TE and 2.25 at LE ( measured at rib centre line this time.) so ribs at 2& 5/16th inch spacing except tip rib which is 3 inch space at TE. 11ribs includes both ends so 10 spaces.
I think it's important not to reduce span on such a small model so it should be 47.75 inch span at least or round up to 48 inch if thats more convenient.
Jeff my plan half measure 23&7/8 thats 10 spaces 2.&5/16 plus the extra spacing of the sloping 3/16 thick tip ribTE makes the 23 and 7/8 half span.Mine is definitely an original RCME plan but could yours be a copy?

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