Original Posted By: "Jack T. Textor"
Brian,The 3/4" spars are plenty strong for your plane as they are, even for an Aircamper (assuming they meet all the specs for aircraft-grade). Both Bernard's later recommendation on this, as well as the experience of probably hundreds of builders proves this. The 1" spars, like much of the rest of the plane, is an over-build. Glue 1/2" wide strips of 1/8" plywood vertically on your spar (both sides) at each rib station and your ribs go on perfectly. If you are using Grega ribs, you should cut down your rear spar to fit that width.Kip GardnerOn Sep 9, 2007, at 11:00 PM, Brian Kraut wrote:> >> I have a very interresting Sky Scout project. The wings and tail were> removed and used on an Aircamper. A new tail was made, but not > covered yet.> New ribs are made for the Grega GN-1 wing. I guess I will call it > a GN-1/2> when I am done.>> I got all of the ribs and the spar material with the project. The > original> Scout plans show spars that are 1" wide and 4 3/4" tall. Front and > aft> spars are the same. The plans show most of the spar routed out on the> inside to give an I beam section that is 1" wide at the top and > bottom and> 1/2" wide in the webs. Makes a lot of sense since you want the > strength on> the caps of the spars. The GN-1 spar plans show them being 1" > thick without> the routed out section at all. The rear spar location is moved aft > in the> GN-1 so the rear spar is only 4 1/4" tall.>> For some reason that I don't understand the spar material I got is > not 1"> thick, it is 3/4" thick although the ribs are still made for 1" > thick spars.>> What I am thinking of doing is running the spars I have through a > planer and> getting them down to 1/2" thick then laminating 1/4" X 3/4" webs on > the top> and bottom on both sides. That will give me the same I beam > section as> shown on the plans. I will glue on vertical pieces at each rib > location and> will glue in plywood sections between the webs where the wing attach> fittings and the strut attach fittings go. This will give me every > bit of> the strength of the original Sky Scout routed spar sections and > likely more.>> A few things I am considering is maybe keeping the 3/4" and just > laminating> 1/4" strips on one side to make it easier to build and stronger, but> heavier. Also thought of doing that just on the aft spar since it is> shorter on the GN-1 wing and would not be as strong in the I beam> configuration with the 1/2" web as the original taller scout spars > are.> Then again, the rear spar does not carry near the load of the front > spar and> the taller spar in the original scout plans is probably overkill > anyway.>> I am also thinking that maybe the full thickness spars like the > Grega plans> show would be best. Who knows, might want to build an aircamper > fuselage> and move these wings and tail to it someday. Already happened on > this plane> once. Are the regular Aircamper original spars routed like the > Scout were> or are they the full 1" thick?>> Thoughts? Suggestions?>> Anyone have any idea how many Gs the original aircamper wings are > designed> for?>> Brian Kraut> Engineering Alternatives, Inc.> www.engalt.com>>________________________________________________________________________________Subject: Pietenpol-List: Good weekend of buildingDate: Mon, 10 Sep 2007 08:04:13 -0500