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Old Mar 10, 2010, 01:40 AM
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Next up - Parting line and plane.

Open up the parting line dialog, choose the pull direction and let it draw up the parting line. Make sure you go over every edge in the parting line since it can choose wrong sometimes. This is where the previous split comes in handy. The split line is exactly where I want it.

After generating the parting line go over to the parting surface dialog. This will be used to split the mold. If you've done the parting line correctly this should be very easy. Just make sure you make it wide enough to split the whole mold.
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Old Mar 10, 2010, 01:49 AM
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Tooling split.

This is where we generate the mold. Simply go to "Tooling Split". It asks you to choose a plane and draw the outline of the mold.

After that it should automatically choose the core, cavity and parting surface. Specify the height of the mold and press OK. I'm using a very shallow height here. Be careful! Milling a shallow mold can cause it to deform. I plan on building steel backing to my mold.

That's it basically! You should have a couple of surfaces and 3 solids. One is the wing itself and another 2 are the mold top and bottom.

You can now cut the other stuff needed for the mold like the rear channel (used for excess fabric runoff) and positioning holes. Don't skimp here. Make sure you model everything you can. I've found out that every time I forgot to model something in CAD I ended up working that much harder to add it later.
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Old Mar 10, 2010, 05:52 AM
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Been busy. Here's the tail.

First up I draw the root chord on the top plane. I also add a construction line which will be used later for drawing the sweep.

I draw ellipses for the LE and the TE. This will ensure that the planform is elliptical. I then trim the unneeded ellipse segments so I'm left with elliptical LE/TE.

I add a tip chord 20-30mm from the tip. On a new sketch I convert the old LE/TE and trim them at the tip chord. I add the tip as tangent arcs. The tip is a 15mm segment with the TE lined up vertically with the tip chord's TE.

Now I add the airfoil and scale it up as before. I now have a wireframe model of the panel.
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Old Mar 10, 2010, 06:06 AM
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Now to make the panel.

Sweep the profile from the root via the centerline we made earlier. Use the "Keep normals constant" option to make sure the profiles stay perpendicular to the profile.

Next we draw the mold. Since there's no twist to this panel we can use a simpler method to do the mold. Extrude the mold as a box around the profile making sure that the "Merge result" option is turned off. This will create a new solid and not eat up the nice panel we just made.

Next we subtract the panel from the box. That means that the main body is the box and the tool is the panel. Once this step is complete we have a nice one piece mold.
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Old Mar 10, 2010, 06:13 AM
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2 more steps before we can split the mold.

1) Drill holes through it. This makes sure they'll be aligned later. I use a single sketch and a rectangular array of holes.

2) TE Channel. This channel allows excess fabric and epoxy to drain out. It also makes it very easy to trim the TE accurately. Create a sketch on the top plane. convert the TE into it. Draw another sketch on the front plane and draw a circle on it. I align the circle with the top plane so when I split it later I get an equal channel on the top and bottom mold.
The circle is 8mm in diameter and placed so the center is 5mm from the TE. This gives me 1m of to trim after I mold it. I don't want to make it in the exact TE since I don't want to damage it.

Now I can sweep cut the channel using the circle and path I just made.
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Old Mar 10, 2010, 06:32 AM
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Now use the "split" command and the top plane to cut the mold into 2 parts.

Use the move command to rotate the top mold alongside the bottom mold.

I add a cut at the TE so I have room for excess cloth to exit. Without this cut the cloth will raise the TE and not allow the mold to close properly. I cut just 0.1mm from each side. This is a very small amount and is just barely noticeable in the finished panel.

Now we have a finished mold. Don't forget (like I did) to mirror it so you have a complete panel.
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Old Mar 10, 2010, 06:37 AM
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Here's the finished mold.
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Old Mar 10, 2010, 09:18 AM
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Nice! cant wait to see the finished cnc molds. What kind of model is it going to be? My only other recommendations on the flying surfaces is:

- consider any mounting feaures on the mold itself, like the wing hold-down fastener holes if thats applicable. May as well use the precision of CNC to get these integrated & aligned now so all wings from the mold will fit any fuse in exactly the same way.

- same for any non-airfoil blending features to the fuse, like if the wing or stab is partially submerged in the fuse top, you will have some remnants of the fuse profile on the LE & TE portion

- if there are going to be aileron/flap servo's inside the wing, consider integrating an outline scribe for the pocket and/or panel covers with the linkage cover boot etc
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Old Mar 10, 2010, 09:49 AM
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It's a DLG.

You're right. I should have added as much detail as possible except that I don't know where I want the lines. I'll probably add a pinstrip for the first couple of wings. Once I know where the hingeline should be I'll scribe it manually. Not ideal I know but it's what I have right now.

Adding the locations for the bolts is not difficult. I can put it back on the mill to scribe the locations. Again, I'm not adding because I don't know.

Fairing will be entirely in the pod.
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Old Mar 10, 2010, 09:53 PM
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Quote:
Originally Posted by erazz View Post
Hi Guys,

I thought I'd do a small how-to on designing a wing and making a mold out of it.
I hope I get the chance to mill it but even if I don't this may answer some questions on how to do wings.


So first up - import the curves into SW and draw up the planform.
I'm using the profiles and planform out of the following thread: http://www.rcgroups.com/forums/showthread.php?t=1139965. The wing is fairly complex with an elliptical planform, under-chambered airfoils and washout.

Let's get started:
First modify the polar so it uses 3 coord for every vertex. Usually polars use X and Y only so here I'm adding the Z as 0.0000.
Make sure that the polar starts at the back and loops to the front. It should also close in on itself so if it started on (1,0,0) it should close on exactly the same coord.

Go to Insert>Curve>Curve Through XYZ Points and use browse to load your curve to the table. Press OK to import your airfoil. Do this for both the root and tip.
I tryed to load a airfoil that way and it comes up invalid file. what am I doing wrong I uploaded the file. I am new to all this and i want to learn this.


Roger
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Old Mar 11, 2010, 12:51 AM
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Hi Roger,

You need to add trailing zeros to all of the points.

Please note that your profile is not closed at the TE. Once you convert and resize it into your sketch you need to close it with a line. Otherwise you won't be able to loft it as a solid.

Erez
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Old Mar 11, 2010, 06:46 AM
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Quote:
Originally Posted by erazz View Post
Hi Roger,

You need to add trailing zeros to all of the points.

Please note that your profile is not closed at the TE. Once you convert and resize it into your sketch you need to close it with a line. Otherwise you won't be able to loft it as a solid.

Erez
Thank you very much
Roger
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Old Mar 11, 2010, 12:15 PM
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Erazz,

Great tutorial.

It has come at the right time for a friend, and myself, in the UK. Do you have any plans to upload the part/assembly files onto the forum? Perhaps the tailplane mould?

Regards,

Martin
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Old Mar 11, 2010, 03:50 PM
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Hi Erazz,
Good tutorial, I am the friend of helibee. I have been slowly progressing with solidworks, to produce a solid model of a tailplane. The problem, I have found is trying to import a aerofoil section. When imported the aerofoil surface wasn't smooth, tried using the spline tool function, with limited success.
But with this thread, now I can complete the tailplane mould, for helibee.
Thank you very much for this thread.
Steve 827
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Old Mar 12, 2010, 10:48 AM
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Hi guys, thanks for the compliments!

I'm adding the parasolid files to this post. If you want the SW2010 files please PM me as they need to be emailed. My only request is that if you intend to mill it then post the results here so we can all see

I've started milling too! I hope to post pictures next week. It's extremely thin. The layup should be interesting.
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