Bob Russell wrote: >> When I trial fit the wings on the project I posted pics of the other day in >> the Facebook site, I did not tighten the nuts onto the bolts (just on loose >> ) but yesterday I checked for movement at the wing tips and there is indeed >> movement. My question for all is ... before you tightened the nuts ... was >> there any movement. << --------- My wing attach fittings on N56ML were originally set up with a tight fit, but after 1100 flying hours and several wing removals and other incidents, they do now wiggle around a bit. It's not a big deal, because it's the bearing of the bolts on the WAFs that keeps the wings intact, and of course the bearing of the bolts against the spruce (this one is the governing factor, according to an analysis that Don Reid did a while back).
The wiggle will disappear as soon as the wings are loaded during takoff, and you'll never see them wiggle in flight, obviously. You'll probably never see them bend either, so you can tell you are way down the scale when it comes to over stressing anything in that structure. At some point in the loading, all four of the main WAF bolts will have a good load on them...there will be no stragglers that are not contributing to support the load. Clamping force of the main 3/8" WAF bolts is not even used in the calculation for this joint's strength...it's all about bearing between bolts, WAFs, and spruce. For example, when our stress guys do calculations for NASA work, friction is not even allowed in the calculation....it's almost insignificant, and there's always the possibility that somebody doesn't torque the bolt properly, so you don't count on that friction load case supporting anything (speaking of bearing loads here, not alternating tensile loads in a reciprocating use like connecting rods). As I mentioned a few days ago, before anything in that system fails, the stub wings will have to be bent something like 10" from the WAFs to the fuselage, and I don't see how anybody could do that to this airplane without hitting the earth in a very bad way at high speed. Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com _______________________________________________ Search the KRnet Archives at https://www.mail-archive.com/krnet@list.krnet.org/. Please see LIST RULES and KRnet info at http://www.krnet.org/info.html. see http://list.krnet.org/mailman/listinfo/krnet_list.krnet.org to change options. To UNsubscribe from KRnet, send a message to krnet-le...@list.krnet.org
