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Airfoil Plotting

Posted By:
Jack Hurdle
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#1 Posted: 5/9/2011 20:19:39

I'm new to CAD -- I need to be able to manipulate the chord/thickness of a given airfoil for a semi-elliptical wing design and then plot it full-size on a roll-feed plotter.  What's out there to do this economically?  Thanks!

Jack Hurdle



Craig Cantwell
43
Posts
8
#2 Posted: 5/10/2011 09:53:54 Modified: 5/10/2011 09:55:35

Any of the 2D CAD programs should be able to do it very easily. Simply lay out you axis, designate your 0,0 location and start inputting the points. Make the moves you need and then connect the points with a polyline. Layout a scale in both axis directions somewhere close to the wing section...something like you see on charts for scales. When you do your final plot, if it's to be used as a template, make sure that you plot it on Mylar to combat shrinkage and stretching from humidity and running through the plotter itself. You can use a good scale or a set of dividers against the plotted scale to make sure you don't have a dimension change in either direction.

 

Hope this helps without confusing.

 



Greg Heckman
Vintage Aircraft Association MemberHomebuilder or CraftsmanAirVenture Volunteer
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#3 Posted: 5/12/2011 12:24:06

Microsoft Excel will even work for this -  simply plot a chart of the X/Y, i.e. chord/thickness data.  Works great!



Todd Parker
Homebuilder or Craftsman
7
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#4 Posted: 5/13/2011 00:17:46

I recommend Profili2. It will plot any size airfoil in various formats and will interpolate the ribs in between two known airfoils. It can also have offsets for skin thickness, lightening holes, spar cuts, etc. If you are using foam cores or wood ribs it will even generate CNC paths for cutting the cores or ribs. It also includes a huge library of airfoils, or you can enter your own. You can also use the X-foil system to design your own airfoil if you wish to go that far with it.

 

http://www.profili2.com/eng/default.htm

 

Todd



Always thinking about airplanes
Mike Dean
Warbirds of America MemberYoung Eagles Pilot or VolunteerHomebuilder or Craftsman
39
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6
#5 Posted: 5/13/2011 08:14:33

There are a number of good, low priced CAD programs available. And some free programs also. Here's a couple I would suggest loooking at:

TurboCAD Designer ($49): http://www.turbocad.com/TurboCAD/TurboCADWindows/TurboCADDesigner17/tabid/1626/Default.aspx

DesignCAD ($50): http://imsidesign.com/Products/DesignCADSeries/DesignCADv21/tabid/1837/Default.aspx

DoubleCAD (Free): http://www.doublecad.com/Products/DoubleCADXTv3/tabid/1100/Default.aspx



John McGinnis
Young Eagles Pilot or VolunteerHomebuilder or CraftsmanAirVenture Volunteer
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#6 Posted: 5/14/2011 00:50:17

Jack,

Don't overlook the fact that this approach will give a non-elliptical lift distribution due to lower Reynolds number. The wing would probably benefit from having higher airfoil thickness percentages outboard than inboard, and airfoils of different shape, to prevent tip stalls and related behaviors. Different chord lengths mean different Reynolds numbers which means different 'design speeds'.



Jack Hurdle
2
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#7 Posted: 5/14/2011 06:24:31

Thanks for the advice gentlemen.  How about a roll-feed printer that doesn't cost an arm and a leg?



Craig Cantwell
43
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8
#8 Posted: 5/15/2011 12:51:58

Jack: A better idea, unless you need to plot quite a bit, would be to take the plot file to someplace like Kinko's or an engineering graphics support place. Even with a sheet feed plotter, you are looking at well past a grand for one that will take 36" wide paper/mylar. I think you can run a plot at Kinko's for just a couple of bucks. You might have to settle for velum unless they run mylar, or have to buy a roll.  Mine is in storage or I'd say send me the file.



John MacKay
Homebuilder or Craftsman
3
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#9 Posted: 5/17/2011 17:39:54

Jack,  Before I build my LSA Whizbang, I'm building 3D CAD models of both the Aircraft Spruce / Wittman Tailwind and the Earl Luce / Wittman Buttercup from plans . For my draft prints, mark-ups and red lines,I am plotting half size on cheap paper (not durable) at Kinko's, 17"x24" at $0.77 each.  Final presentation prints on Bond @ $4.60 or dimensionally stable for forms and molds, on Mylar @ $5.00 per sheet..

Plotters at home are great for convenience, but a way spendy.  Save your money for your instrument panel.



Spencer Gould
Homebuilder or Craftsman
32
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1
#10 Posted: 5/21/2011 21:43:28

  Normal 0 false false false MicrosoftInternetExplorer4 st1\:*{behavior:url(#ieooui) } /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-ansi-language:#0400; mso-fareast-language:#0400; mso-bidi-language:#0400;}

I’m using a decade old copy of Autocad R14 for my own homebuilt design, you may be able to find old copies, works great for 2D stuff.

 

As for 3D the best budget system I’ve seen is Alibre

 

http://www.alibre.com/

 

starts a $99 and goes up to a grand that would give you full FEM and CAM. I’m using the full blown package on some robotics consulting work.

 

As for printing on my project I set up a grid that fits a 8.5 x 11 on the part I would like to print then I just send it to the printer, I have some alignment features and a long axis line or chord line on the grid so I can cut and tape it all together. The printer is accurate to with in .030 witch is more then enough for airfoil work. this is by far the cheapest way to go.

 

If your going to pay someone to print your airfoil I would highly recommend giving them a pdf, note:  plot files a notoriously a giant pain in the…. For both users and the print shop.

 

You can download a free & legal pdf creator at http://sourceforge.net/projects/pdfcreator/

 

You just select the pdf creator instead of your printer in the print setup. The settings will confirm the size. Make sure you have the scale set to 100% and the paper size is right i.e. arch D for a D size print. Etc…

 

I would have some gauge points on the cad file as far apart as you can get so you know you are getting a 1 to 1 print.     

 

Hope this helps,

 

Spencer Gould

 

EAA 466275

 

Technical Counselor 5426

 

Note: I drive Unigraphics NX6 / Teamcenter for my full time job.

 

 



Mike Dean
Warbirds of America MemberYoung Eagles Pilot or VolunteerHomebuilder or Craftsman
39
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#11 Posted: 5/27/2011 13:13:18

Jack,

You don't indicate what a reasonable value would be for an arm & a leg (wink) but...

The HP DesignJet 111, 24" with Roll, is only $750. (http://www.shopping.hp.com/webapp/shopping/can.do?landing=printer&category=Designjet&catLevel=1&storeName=storefronts). You maybe able to find it for less, either via an online dealer, or through a local CAD/Drafting vendor.

Or you could check out Plotter4U (http://www.plotter4u.com/) for used, reconditioned plotters.



Mike Dean
Warbirds of America MemberYoung Eagles Pilot or VolunteerHomebuilder or Craftsman
39
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6
#12 Posted: 5/27/2011 13:35:00

Danged Oshkosh 365! For some reason it won't let me edit my own post. Errrrr!!!

Oh well... I wanted to add a post-script to my above post. I found the HP DesignJet 111, with Roll, for $680 on ebay. (http://cgi.ebay.com/NEW-HP-Designjet-111-24-Large-Format-Inkjet-Printer-wi-/150605278540?pt=LH_DefaultDomain_0&hash=item2310c62d4c)

 



Jack Moon
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#13 Posted: 5/28/2011 16:36:27
A Question for John MacKay,

Hello John,
That was good advice you gave to Jack ... use the same technical blueprint/copy companies that the consulting engineers use. The most accurate prints available ... and can be cheaper than Kinko's.

Now, my question: What 3d Cad program are you using? I would like to layout a tubular fuselage in a 3d format but have found dealing with tubing of various sizes and wall thicknesses to be a headache (I've been trying to use SketchUp). Will the program that you are using allow for the creation of a basic 3d design of tubing which can be stretched or shrunk to the size required for different applications and then moved and rotated to fit in the space required?

Thanks
Jack Moon





John MacKay
Homebuilder or Craftsman
3
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#14 Posted: 6/18/2011 10:47:12

Jack, sorry for the delay, have not been back to this site in a while.  I am using AutoCAD 2011 to build my 3D model. This LSA design is my interpretation of a blend of the Wittman Tailwind & Buttercup using registered plans from ACS and Earl Luce for reference.  Great thing about working in 3D is that I can rotate the part, or tube clusters and see exactly where to miter, stretch, push or pull the various pieces to get the alignment and fit that I want.  It may seem like overkill, but it also lets me more fully understand my project.  Yesterday I modeled Calbie Wood's aluminum wing and increased the span for my project.  Better to measure twice then cut once.  What kind of fuselage are you modeling ?