Wing Ribs.
Building Tips
Introduction Wing Joining Wing Ribs Graphics Thrust Angles Manifolds Exploding the Myth
Here's a method for producing very accurate wing ribs from balsa. It takes around two hours to complete the process from start to finish and works well for tapered wings.
Any 2D CAD drawing package can be used although AutoCAD LT For Windows is what's been used here. There are some good low price drawing packages available and several have been given away as freebies with some of the computer magazines (ie. bCAD 2.2 PC Plus April '98). A CAD drawing package can be used for loads of other applications (Come back later!!!!)
Draw out at full size the root and tip profiles for the wing you are building.
 |
Draw out the wing profile and position the two ribs at the root and tip of the wing.
Note that if the wing you are making is parallel, you needn't bother with this step or the next.
 |
Mark in the wing spars, leading and trailing edges and the rib positions. Note that the ribs need neither be equispaced nor the same thickness. Scale each of the ribs to it's proper length.
 |
On each rib, mark in the cut outs for the spars then offset each rib profile by the sheeting thickness you are going to use for the wing, (usually 1.6mm (1/16")).
 |
Remove (or turn off the layer containing) the wing structure and you should be left with all the wing sections shown.
 |
For each rib, remove the spar, web and outer profile and you will be left with the true rib template.
 |
Reorganise the rib positions so that you can get as many on a sheet of A4 or whatever size of paper your printer takes and print out the rib templates, remembering to print at full size! If you can get your hands on the self adhesive stuff, so much the better. You'll also need two copies of each rib profile. Don't use a photocopier for this as a true copy is not always given!
Cut out each rib slightly oversize and use self adhesive tape (or the self adhesive printed paper!) to fix the templates to appropriate sheets of balsa. You should be able to get virtually no wastage.
Using a surgical scalpel or whatever, cut out each rib. The advantage here is that the paper template stops the cutting edge from folloing the grain of the balsa.
You should now have a set of perfectly sized ribs.
This system works most easily for any wing which uses the same aerofoil type at the root and tip. Where the root and tip sections are different types, more effort is required in the rib scaling stage as a point to point method will have to be used.
Building Tips
Introduction Wing Joining Wing Ribs Graphics Thrust Angles Manifolds Exploding the Myth