topic Re: Drawing wings with washout (twist) in Fusion Design, Validate & Document Forum

Drawing wings with washout (twist)

Anonymous — Tue, 31 May 2016 01:28:19 GMT

Hello guys,

Getting towards the wing part of the project I'm working on on and off, and before I start I am running into a problem of how to draw it.

In SW, this was my basic workflow:

Import all airfoils
Draw reference plan form
Create a spline for the leading edge (LE), and a spline for the trailing edge (TE), using the reference sketch as reference
Create planes along each station in the wing for airfoil placement
Project the airfoils to their respective planes, scale, and add in appropriate washout (rotation/twist). This is usually along the hinge area, so the LE and TE both do not intersect with the LE and TE splines, which was OK in SW but not OK in F360 since it seems profile must intersect once with the rail.
Loft

I am having trouble wrapping my head around how to create the LE and TE splines in 3D space, and more so because the airfoil stations with washout is spec'ed at an angle for the airfoil itself, so I don't know the Z axis displacement of the LE and TE either.

What do you guys think? And, would there be another drawing workflow you would use in F360 to achieve the result?

Thanks!

Thomas

Re: Drawing wings with washout (twist)

davebYYPCU — Tue, 31 May 2016 10:31:22 GMT

I am not near my Fusion system today,

your workflow is more complicated than it needs to be, depending on your shapes, I will presume you

need three different airfoils for your half wing, straight leading edge in front view.

airfoils are true size in Fusion.

I would do your step 1 and 2.

Then place (snap) root rib leading edge zero - zero on the reference leading edge, with chord line zero degrees.

then position rib 2 on the parallel plane, snap leading edge zero - zero of this airfoil on reference leading edge. Use move command to rotate the respective washout, with rotate point being the Le snap point.

do this for tip rib, snap, then rotate for tip washout.

now you can create "3D sketch", then project include, each of the trailing edge points.

Connect 3 point trailing edge (spline?) shape using reference as a guide

you can test the loft command for errors all points are connected, etc.

i would then, create a plane for top and bottom spar position (front view). Create sketch on this plane, Project intersect each airfoil. For loft I do two sketches here one for top and one for bottom sheet definition, use these points snap spline curve shape to suit.

Loft with 1, 2, 3 ribs for the profiles, then add rails, top, bottom, Le, Te. Loft gives you a preview if all is ok on each selected curve, or an error. With successful loft, mirror the loft with rib 1 face for the full wing.

This workflow works for me, but I get problems with the next bit, shelling for wing skin with sharp trailing edges in Fusion, still working on a workaround.

Browny.

Re: Drawing wings with washout (twist)

Anonymous — Thu, 02 Jun 2016 08:53:50 GMT

Hey Browny,

Thanks for the quick reply!

I will give that a shot, the difference will be rotation is at the bottom surface of the hinge location, so that the hinge is as straight as possible.

Our TE's are not sharp since that is not replicable in real life, taking into account of the top and bottom layers of carbon it'll be approx. 0.4 - 0.6 mm thick depending on the fabric we plan to use, so, we shall see whether that becomes a problem or not for me. I'll give it a shot this week and report back the result 🙂

Yours,

Thomas

Re: Drawing wings with washout (twist)

davebYYPCU — Thu, 02 Jun 2016 12:04:11 GMT

Yeah ok Thomas, I tried to paint the picture in your mind, so it can proceed with specific data.

if you use the hinge position for the rotation, then I think you will need the LE as a 3D sketch as well.

Whether you get a straight hinge will be dependant on the airfoil shape/s, together with construction methods later down the track.

Browny.

Re: Drawing wings with washout (twist)

Anonymous — Wed, 14 Dec 2016 16:07:26 GMT

Howdy, newby here

I am about to draft a sailplane I designed in XFLR5 that uses washout throughout the span. I too need to rotate on the bottom surface of the hingle line located 30% from the trailing edge.

I tried the method described above, but the move command applied in the sketch does not even move/rotate the spline. Here is what I did:

Downloaded the AG24 airfoil, post processed with Excel to scale, converted chords to required scale and in cm (result is attached).
In Fusion360, Scripts and Add-ins, Import spline from csv file
Double clicked on my post processed csv file
Result = airfoil is imported and visible, it is still open at the trailing edge (not closed)
Edit the sketch created by the import
M (move command)
Selection = Select all 161 points
Set pivot to a point on the bottom surface
Grab the handle to change the X Angle
Result = the handle moves but the points do not 😞

Help will be greatly appreciated.

Re: Drawing wings with washout (twist)

davebYYPCU — Thu, 15 Dec 2016 01:22:36 GMT

Almost there, you need to confirm that new pivot point position, with green tick box,

So move to pivot position, tick green box, then roll airfoil and in the text box you can type the angle if you know it, or, move then OK.

Time zones didn't see this one for a while....

Re: Drawing wings with washout (twist)

Anonymous — Sat, 24 Dec 2016 19:33:15 GMT

One possible solution is to import airfoils that are rotated the requisite mount.

I suggest that the rotation point be at the aileron or flap hinge line (if there will be one) on either top surface or bottom surface (perhaps as a loft guide rail). That way the hinge line comes out straight(er).

Re: Drawing wings with washout (twist)

Beyondforce — Sun, 25 Dec 2016 03:07:58 GMT

Hi @Anonymous,

Welcome to Fusion 360.

If you could screencast your model and what you need, it will be very helpful.

Cheers / Ben
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Re: Drawing wings with washout (twist)

Anonymous — Tue, 02 May 2017 05:25:26 GMT

I have prepared screencast how to construct a wing including winglet. Hope it helps: https://knowledge.autodesk.com/community/screencast/6050dc36-fa43-48ec-a5da-07bca22bb55d