3D Romeo

My Feedback: (111)

Hi,

I'm trying to draw up an airplane in AutoCAD and was wondering if anybody knows how to make a tapered wing using solid modeling?

I have the tip and root rib drawn up as Polylines right now, and the rest of the lines are just there to help me visualize what the wing will look like when done. My first attempt I started off with a solid block the size of the wing and then sliced off a piece at a time until it looked close to what the wing was suppose to be. But I didn't care for the results. So I was wondering if anybody knew how to model this correctly, where the wing would retain the smooth airfoil shape instead of looking rather rough with edges at all the endpoints and tangents?

I hope somebody can help me? []

Thank You,

Mark

cltom

You need to define the root rib or the tip rib as a region, then extrude the shape to the other end of the wing. When you extrude, carefully calculate and input the scale reduction (or increase) of the airfoil, and the axis of extrusion. This will give you the taper and result in a perfectly smooth extruded shape.

dr_wogz

My Feedback: (3)

While that will work, I doubt it'll give you teh results you want.. That will taper teh whole thing by XX scale amount. and that might mean your tip is miniscule!

This is ultimately a lesson ins surface modelling, and from what I remeber, Acad isn't all that great at surfacing. You'll soon find it confusing. The Mechanical Desktiop parametric modeller extension for Acad will make your life a lot easeir, or find another parametric modeller, such as solidworks, or Adesk's Inventor.

Sorry, But as a seasoned Acad user (2D & 3D and 'parametric modelling'), I beleive you are trying to create soemthing that might be best left to '2D' land drafting.

From what I do remeber about surfacing, youi'll need to define teh lines to create teh plane. What you'll eant to do, is select teh root & tip 'upper half' lines, and teh trailing / leading edge as the other line (rail I beleive is teh term) and create the surface. Repeat fort eh bottom surface, and one fort eh sharp TE surface, and one foe ht tip , and then one fore th root template . You'll then have to 'stich' these 5 or 6 surfaces togethetr to create a solid model. One mistake, and you'll be re-building it... Oh, and your 'wing profile templates' Root & Tipe templates shoudl be made of at least two plines, one top and one bottom.

3D Romeo

My Feedback: (111)

Thanks for tips guys...But...

I kinda gave up on my dream of modeling the wing in ACAD and had my brother model it for me using VISI. He said it was very easy in this program and only needed the 2 PLines to generate it. Then he just exported it back into ACAD.

I may play around with ACAD a little more in the future just to see what kind of results I get.

Anyway, Thanks again for the replies!

Mark

cltom

You are correct. Unfortunately my MicroStation experience is showing. Scaling independently in all three dimensions in MicroStation is basic drafting. It existed in the first data definition of Intergraph IGDS before MicroStation was a glimmer in the Bentleys' eyes.

While drawing in 3D with MicroStation, you don't scale by "XX scale amount." You scale by XYZ amount, and each is infinitely variable in each axis. If the tip rib is a 25% section, while the root rib is a 20% section, then your Y scale would be 25/20 = 1.25. If the root chord is 12 inches, while the tip rib is 10 inches, then your X scale is 10/12. Z would be the axis of extrusion, which you would set to a point midway between the spar notches on the root and tip ribs.

Actually, with the advent of Mstn SE (6 yrs old at least!), you could extrude a surface to connect any two shapes - with a single command: "Construct Skin Surface." Draw the root rib, scale and copy the tip rib from the root at the desired 1/2 span distance, and select the shapes to construct a surface skin to connect them. It also allowed you to select the axis as a "trace curve." This meant that you could actually extrude a tapered wing with an elliptical taper rather than a straight line.

There is a Lisp command called Xscale.Lsp at http://www.spaug.org/LISP_Index99.Html. it's supposed to let you scale independently in 3 dimensions. Perhaps that will make up for AutoCAD's mickey mouse limitations - yuck! This stuff is in the basic MicroStation CAD program right out of the box.

Balsa Master

why are you doing it in 3d? make it 2d ans just scale each rib by whatever decimal you want to make it smaller then align it on a rib and trim out the spar notches and lightening holdes. (unless you want to see the plane in 3d...)

3D Romeo

My Feedback: (111)

Yep...It wasn't a matter of life or death. I was just trying to model it up in 3D for fun.

Thanks again for all the replies!

Mark

mulligan

If you're interested, I've written an AutoCAD application for creating 2D rib shapes for an airfoil with taper, dihedral, and separate root & tip sections.

PM me if anyone wants a copy- I call it G-Wing.