Hi Guys. The bracing I used are 4 x 1.5 and the screws are 6G which are pretty thin. I pre-drilled the bracing timbers all the way through with one hole at each end. I then marked the drill bit with masking tape at the 2" line and went through the bracing and into the spar caps 1/2". From memory the drill bit used was 3/32". Pre-drilling the holes avoided any chance of the screws splitting or bruising the timbers. Second screws were used in the end of the braces after the first were "nipped up". Considering the strength of the added floxed struts, I could probably remove the bracing anyway. The spars are not about to move in any direction. When the time comes I will fill the 1/2" long holes with T88 as they are too small for dowels.
I can not imagine there is going to be any impact on spar strength given that we drill 1/4" holes right the way through the main spar for the landing gear brackets. This area of the spar must take a hell of a pounding given some of the landings people have admitted to. I have heard of gear legs bending so far that wheels have punched up through the wing skin, but never the spar snapping. And all those 3/16" bolt holes concentrated where the WAFs attach don't seem to cause any strength issues. I wasn't at the 2008 Gathering but I am very impressed with the spar that was tested to destruction. http://www.krnet.org/mvn2008/ .......and my outer spars have webbing on both sides. I thought long and hard before using the bracing option and considered it to be a non event given the above examples. I appreciate the concerns. Thanks guys. -- Darren Crompton AUSTRALIA My web site: www.kr-2s.com
