CAD package specifically for designing wings for laser cutting

Whilst not a CAD package specifically intended for designing wings MOI done a good job on this test.

OK here is the elusive elliptical wing with a 2 degree washout

This was created in around 20 minutes with the programme called MOI that I listed right in the first post.

The reason that I created this dummy model was to show that 'one tool may not fit all' but to be fair Fusion 360 actually does a pretty good job if the only thing it struggles with is doing a washed out elliptical wing.

We should probably discuss the work flow on this part rather than the programme though.

This my workflow for the elipical wing using MOI, it certainly sets up some framework.

The CAD package which I completed the dummy elliptical wing with is a surface modeller (NURBS Non Uniform Rational B Spline).

3D Surface modelling is a bit more like building an airframe up from bits and pieces of strip wood, in the CAD speak these are called wires, we then drape a surface and imagine that to be like a covering film across the structure.

So for this wing, I defined the plan view eclipse, which was quite easy. But I really need to create that eclipse In a 3D space (remember we have 2 degrees washout) as it will form the leading and trailing edge of the wing. So I extruded the plan view wire upwards but this just the wire getting extruded and creating a vertical elliptical wall.

I now create a surface that is bigger in all directions than the plan view eclipse and has a 2 degree twist (washout), I trim the larger surface which has the 2 degree twist to the vertical eclipse surface. I can now extract the wire from that edge and this is the wire that is in 3D space and forms the leading and trailing edges.

I then setup 4 scaled sections down the span of the wires. One of these sections must very definitely be at the root, it helps if there is one section close to the tip, say about 10mm inboard of the tip, I then set the other two sections up roughly equal spacings between the tip and the root. We then create the surface selecting the leading and trailing edge wires along with the four sections and hey presto we get the wing surface.

If we don't have these additional sections to hold the surface up it kind of sags in much the same way that some covering might do if you stretched it across too big an area.

NURBS surface modellers such as Rhino and MOI are quite good at organic modelling.

(14) Car modeling in Moment of Inspiration (MoI) (SUV Modeling) and 2 Ways to get a Seamless Surface - YouTube

(14) MOI 3D WZ-10 Modelling [Part 1] - YouTube

The second link shows some great reverse engineering which is a nice way to create scale models from 3 view plans.

Post originally by

HI - SO BEEN PLAYING WITH TWO PIECES OF SOFTWARE - AND I THINK ALL THIS DEPENDS ON WHAT YOU WANT TO GET OUT OF THIS AND MORE IMPORTANT - HOW MUCH TIME YOU WANT TO PUT IN !!!

AT THE BOTTOM END OF 2D CAD - SO SAY DESIGNING A WING AND WING RIBS - SO YOU CAN CUT OUT RIBS OR BETTER - LASER CUT - I THINK JUST STARTING WITH - WING HELPER - WOULD BE A GOOD PLACE TO START - THEY DO A TRIAL VERSION - SO YOU CAN PLAY - AND GET TO UNDERSTAND - RIBS - SPARS - LEADING EDGE - TRAILING EDGE - ETC - AND IF YOU WANT TO PAY FOR IT - PRINT IT ALL OUT

BUT THEN FURTHER UP THE SCALE IS DEV WING - WHICH FOLLOWS THE SAME PRINCIPALS - AND ALLOWS YOU TO GO A BIT FURTHER -  AND SEEMS TO DO JUST ABOUT EVERYTHING - SO PLEASE CORRECT ME IF I AM WRONG - THIS SEEMS A GREAT PACKAGE - FOR 2D WORK - DOES THE ELLIPITAL WING WITH WASHOUT - BUT NOW MOVING UP TO 3D - I AM LOOKING AT FUSION - BUT AS A 3D CAD PROGRAM - YOU HAVE TO THINK COMPLETELY DIFFERENTLY AND THINK IN 3D - WILL REPORT BACK WHEN I HAVE PROGRESS - BUT AS I HAVE SAID - ALL THESE PACKAGES REQUIRE SOME TIME TO GET RESULTS - THE BIGGER THE PACKAGE THE LONGER IT TAKES - AND TE CHOICE OF 2D OR 3D - LASER CUTTING OR 3 D PRINTING - HOPE THAT ALL MAKES SENSE - THANKS - DAVID

@pylonuk nice detailed post Barrie, I’ll do the same for what I’ve done in Fusion 360 but it will be quite a long post!

Steps I take to get ribs for laser cutting for an elliptical wing with washout.

Create plane for root rib. 

Create sketch on root plane and import airfoil section.

Create horizontal plane going through airfoil LE ‘nose’ point and TE ‘tail’ point.

Create sketch of elliptical wing shape either by free hand or trace outline from image file (jpg, png or tif) using the insert decal function. Note separate line for LE and TE.

Create offset plane for tip rib.

Create sketch on tip plane and import airfoil with washout, lining up LE ‘nose’ point with horizontal plane.

Create 3D sketch line between LE ‘nose’ point on root rib sketch and ditto on tip rib sketch.

Create 3D sketch line between TE between ‘tail’ point on root and ditto on tip rib.

Create plane on line of LE 3D sketch and project elliptical LE sketch.

Create plane on line of TE 3D sketch and project elliptical TE sketch.

Surface loft root airfoil sketch to tip airfoil sketch using LE and TE elliptical sketch lines as rails.

Create new rectangular sketch on root rib plane and apply the Surface tool Patch.

Create rectangular pattern of that throughout the length of the wing at C/C to suit.

Using the split face tool, select all of the rib faces that have been created and split them using the wing skin.

Save the individual ribs as DXFs for use in Lightburn.

Further to my post above.

I’m not sure if the following feature is only available in the purchased copy of Fusion 360, I’ll have to check.

To extract the ribs as dxf files in one go I use the Manufacturing Arrange option. This provides a nesting function whereupon the individual pieces are laid flat on a sketch of a measured surface (balsa sheet) and the result sketch can then be exported as one DXF.

I hope to show this in a future webinar.

@rong In Manufacturing Arrange is there any options for grain direction? This has always been my issue with automated nesting programmes, as they assume the materials the same properties in all directions (quasi isotropic) ie no grains or wave patterns to respect.

@pylonuk Yes you have the option to select the grain direction.

@rong Very well thought out then.

@pylonuk it is quite impressive, the more you look at and use Fusion 360 the better it gets!

@rong A friend of mine is doing some simple projects (not aeromodelling) using Fusion 360 and he was struggling, I went to help, I have never used Fusion 360 but was able to get the required results (very easy stuff) straight away, it is a very well thought out programme.

@pylonuk I think that as long as you understand the basic concept of construction planes>sketches>bodies then you can work your way through it.