Rear Spar – Sonex 1362

January 13, 2013August 22, 2018

Fit Rib Gussets and Ribs To Wing

We located the gussets to the ribs. There are a lot of holes on those parts

Match drilling the ribs to the spars took some thought. Since we are scratch building, the pilot holes are located in the spar and the rib flanges are blank. The basic process for the right wing was:

1) Lay out spar for wing station locations

2) Align and clamp the FWD ribs to align with the upper and lower spar caps using procedure described in plans for overlap of wing skin.

3) Match drill the FWD rib then remove.

4) After all FWD ribs have been matchdrilled, clamp spacers (Wxx-x and Wxx-x) in correct location at each wing station for AFT ribs and then match drill.

5) Tape spacers in place and then remove clecoes.

6) Clamp AFT ribs at proper alignment with top and bottom of spar cap and match drill.

Ribs to rear spar

Return To Wings – Ribs

March 28, 2012January 13, 2018

Complete the Bending of Rear Spars

Here are some pictures of finishing the rear spar bends. As usual the first time you try something new, like these really long bends, it takes a while and you learn the little subtleties. For example we noticed that the ends of the bend would form much more than the center, slightly bowed, perhaps the center of the brake is bending a little. Since we have to go past 90 degrees we have to bend it a second time since the brake can only rotate 90 degrees before it binds. We have to bolt another flange (or a peice of wood) onto the brake. Well if we don’t push at the ends for this second bend it all seems to average out.

Here we can see that we got the first flange angle but it looks pretty wavy along the length

When you bend the flange on the other side it all straightens out:

That looks awesome!!

Here are the two completed rear spars. These are the long lengths (108 7/8″) so we don’t need the splice plate (snx w12-04).

During this process you can see we were using lots of C-Clamps. Here’s what happens when Dan wants something tight:

Return To Wings – Rear Spar

March 25, 2012January 13, 2018

Rear Spars First Bend

Since we finished “Big Bend” (the David Clay bending brake design) we were eager to try out the beast. This is the method we have developed for accurate bends.

Here is the rear spar cut to shape and edges deburred and smooth. One can calculate the width from the standard bending formula tables. We mark the centerline of the spar blank

We clamp the flange side in the bending brake so we can push up against the larger center portion. From the bend formulas you can calculate the tangent points of the bend. Since the part will be formed around the radiused nose of the brake, we need to locate the part’s tangent line right on the tangent line of the nose of the brake. How can you do this if the part’s tangent line is covered up? What we need is called the “Sight Line”. Looking straight down on the un-bent part this theoritical line should be located right at the nose of the profiled brake angle. It happens to be the radius of the bend from the tangent line. I will post a summary of this with lots of pictures. It is tricky to get this line in the right position visually, so we use a caliper and measure from the center line out to the nose of the brake. (In the picture below we are using the top fingers of the caliper. The paint on brake nose was sanded off so it is a bit shiny.)

Tighten up the clamp bolts on the brake

** Important ** When we clamp on the narrow flange section we have less than .5″ of the sheetmetal clamped so the top angle will tilt back since it is 3″ long. This reduces the clamping force and the little flange can slip during the bend. We insert shims of the same thickness of the bend piece in the backside of the clamp to keep it level.

Here is the first bend, we can only get about a 90 degrees (with the spring back) since we can only rotate the brake up a little more than 90 degrees.