Begin' Acro Glider

I'm guessing the spar slots are a perfect fit which makes the ribs line up perpendicular to the spar. But the wing requires the spar to be swept back so you will need to lightly sand the spar slots to allow this. You don't need to be too anal about this because the wings strength comes from the spar and the sheeting, not a perfect spar slot

Hi Colin,

Here's a link to the plan PDF: www.topmodel.fr/goodsdoc/100007_time_1331831088.pdf You can see the wing and the reason for my query, I guess it's not a conventional shape.

Thanks Mike, I figured it probably requires little fettling, but just wondered if there was a trick to it that I didn't know.

Chris - Thanks for link - all is clear now.
Colin

MikeSeale wrote: ... You don't need to be too anal about this because the wings strength comes from the spar and the sheeting, not a perfect spar slot

I can't help thinking that Mike is hinting that I might focus on the minutia too much

Anyway I decided the first step was to get the leading and trailing edges to sit at their respective angles without being pulled out of shape by the ribs.

Through careful calculation i determined that the leading edge lugs of the ribs required a 6º taper. To demonstrate a relaxed approach to these things I rounded it up to 6.5º and created a wedge.


With a chisel following the taper of the wedge I removed the offending 6.5º

The result is that the ribs, leading and trailing edges slot together correctly without any tension.


Further work will be required to fettle the other parts of the wing.

A little rough fettling of the spar slots and the wing slotted together without out tension.



I've put the two halves together, back to back, and was pleasantly surprised that they line up with each other. There will be a little finishing off to do before I can glue the first wing skin on, but that will have to wait for another evening.

The bottom of each wing is now sheeted, I used magazines to weight it down and conform to the shape, next time I'll used a ream of paper, as this will follow the shape of the aerofoil better.



Sheeting the top is going to be fun as there is the potential to twist the wing.