The vertical shear spar loads will not drop to zero inside the fuselage, unless the seats are mounted to the longerons instead of to the spar as they normally are. The horizontal shear loads caused by the bending moments remain constant (not zero) inside the fuselage if there is no vertical load applied to the spar inside the fuselage.
-- wesley scott [email protected] Message: 16 List-Post: [email protected] Date: Tue, 8 Feb 2005 18:30:56 -0600 From: "Bubba" <[email protected]> Subject: Re: KR> Question on bent spars To: "KRnet" <[email protected]> Message-ID: <067901c50e3e$a007bcb0$0200a8c0@Katana> Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original Ron Smith wrote: > I plan to make my spars with the dihedral bend at the fuselage. Mark > Lankford wrote that this bend might occur inside the fuselage. > > If they are built that way I don't see how they can rest on the > bottom longeron, and still be in plane with the rear spar. (because > of the taper) > > I plan to bend mine just after the fuselage wall. > > Am I missing something? I'd a bit hesitant to put the bend at the fuselage sides. Spar loads are highest right at the sides of the fuselage and drop to zero inside the fuse. Bending the spar instead of cutting it is certainly stronger, but I still don't know if I'd want the bend right there. If the bend is inside the fuselage you just have to move the spars to set the incidence. It may very well put the wing higher on the fuselage than intended, but I doubt that would be an issue aerodynamically. Worst case you have to build a foam and glass belly pan and make the bottom of the fuselage rounded like the turtledeck and front deck. Hey, here's a thought, why not get some good, straight grained pine and make a couple of test pieces? Make one perfectly straight and the other bent and see which breaks where. Or even balsa would do. It isn't a test to see how strong the actual spar is, just whether the bend costs strength. -- Steve N205FT [email protected] He who seeks will find, and he who knocks will be let in.
