Re: [RCSE] CF on spruce spars - on the right track

[Hilaunch]

In a message dated 8/20/05 8:23:31 AM Pacific Daylight Time, [EMAIL PROTECTED] writes: I have in the past bagged CF to existing spruce spars, but have never  been sure whether to put the CF on top of the top spar, or between  the spar and the shear webs, same with the bottom.  It does seem to  make sense to put the CF between the spar and webs to avoid de- lamination Barry,       Nearly all of the wing failures are in compression, meaning the top of the wing fails first.  In extreme cases, sections of the wing near the root will be missing entirely (turned to dust) from the force of the failure.       Therefore it makes sense to stiffen the upper spar a bit more than the lower.  In the past I have used .014 pre-preg for the upper spar and .007 for the lower.  As you observed CF is better in extension than compression.  Ideally, placing the CF in the middle of the upper spar would provide great strength, but placing it under the spar and on top of the shear web (and ribs) should suffice.       Look forward to seeing your new Challenger.  I too have one in a box and am searching the web for a barrel of patience before I start building it.   Don Richmond San Diego, CA [EMAIL PROTECTED] www.hilaunch.com