I’m not sure of the best way to describe what I typically do and I’m sure you will have many questions after I outline the steps briefly here so it may be better to pm me and we can exchange emails unless you think the question will be of general interest to others.

• I draw everything in AutoCAD 2002 and it’s all in 2D.
• 1st draw the wing plan, only one side is needed to start with, place all ribs and spars with proper thicknesses shown
• Generate rib for wing, I trace a known wings root and then draw it with the CAD program
• Draw a thickness profile of the wing at the high point of the wing, offset for wing sheeting, now you have how thick each rib is
• Draw each rib using the plan for the length of rib and the thickness profile for the height of each rib
• Align ribs on the side of the plan and draw construction lines at locations where each spar cuts thru a rib, usually this will be on the top and bottom of each rib
• Draw lightning holes in each rib
• For spars I take a line parallel to the spar, draw lines from the end of the spar perpendicular to the new line, copy the perpendicular line to each location where the rib crosses the spar, use each rib to generate the thickness of the spar where the two cross

At this point the spars and ribs should be done, to do the special locations similar techniques are used of drawing lines parallel to the parts plan line and perpendicular to get length and then measuring the ribs or spars at each end of the part to get the thickness.

Ok half way there now, the parts for the wing should be done now onto the jig.

The jigs that I have been doing are symmetrical so only one set is required, the center line of the wing is parallel to the table. Also with 3/32” sheeting and the gentle slope of the airfoil only one set of jigs are required.

• I lay out the jig ribs / spars and spacer spars on a wing plan, just copy the wing plan and modify it for the jig
• All jig ribs under the major wing ribs, jig spars under main wing spars – I do this to help prevent the potential of the wing sheeting bulging when using Poly-U glue to sheet – place spacer spars at the LE & TE and then some within the plan itself – these will help maintain the spacing of the jig ribs
• I start at the root rib and see/guess how much material is needed at the high point to provide enough strength to the jig, typically if you offset the rib center line 1.75” there will be enough material
• Offset the center line at each rib the same amount, draw notches for all spars crossing each jig rib
• Draw spacer spars same way as wing spars

Now the two plans are done and all the parts for the wing and jig. At this point you will need to talk to your laser cutter and see how he wants it arranged on the wood. The cutter I use wants a 1/8” no cut
zone around the wood sheet and have tabs – uncut lines – so the parts stay in the sheet after cutting. I then arrange all the parts on the correct thickness wood with as little space between parts to save on material cost.

Hope that briefly explains what I have been doing and I’m sure there are much better ways to get the info generated and I hope others let us know how they do it.

Dave Snow