Ribs Preparation

8/21/2005

I have decided to build the ribs, so I can get started. The manual (if you can call it that - several sides of A4 text for the whole build) recommends starting the steel fuselage first, but I am more comfortable with wood fabrication (ex-cabinet maker). I will make the ribs / aileron ribs, then either pack them away and start the fuselage, or carry on and build the wings..not sure yet, since building the wings takes up a huge amount of space. If I can work out where I could store the finished wings, then I will probably build them before the fuselage.

I have decided to make the ribs out of birch aircraft grade 12-ply as opposed to the trussed/gusset type - this will save literally dozens of man hours, with only a weight penalty of approx' 7 pounds. The ribs will have lightening holes in strategic places.

Rib Fabrication Method

Basically I need to make 2 finished ribs as templates (top and bottom wings). Then all one has to do is temp' fix the template to a plywood piece, and run around it with a router fitted with a trim cutter that has a bush guide attached to it - the bush guide will follow the template contours, resulting in a perfect rib clone of the template...viola! When the ribs are made, I can then cut-off the trailing edge part of the template in order to fabricate the shorter ribs where the ailerons are positioned....this saves making 4 templates.

To make accurate templates, I got the full size rib blue-prints copied at Fedex Kinkos ($5 per copy). I then cut-out the ribs with scissors, leaving a 1/2" border. I will be glueing these cut-outs to a 1/2" piece of mdf. Once glued, they will be run through the band-saw, cutting about 1/8th" outside the line. Final finishing will be by using the bench mounted sanding disc or belt sander.

The belt sander pic below was an idea I had. Bench-mounted belt sanders cost a great deal of money, and the cheaper ones like at the Home Depot were not set at a right-angle to the user (I found one, but that was over 200 bucks). So, I created a jig that holds a hand-held belt sander at a right-angle. How is it clamped solidly in place? - It's clamped via a wedge of wood against the motor casing underneath....works great. Just ensure that the right-angle is setup at a true 90 degrees.