lml@lancaironline.net Mailing List Archive

With all of this discussion on max gross weights for the Lancair 320/360, what is the engineering/design decisions that has gone into increasing the gross weight? The reason I ask is that, I assume, the factory has done some type of engineering analysis. The factory increase in gross weight document is: http://www.lancair.com/media/builderupdates/235-320-360/Non-PDF-Docs/WeightI ncrease320-360.pdf Here, it states that the new main gear overcenter link must be used (Standard in kits produced after 10/93), the stall speed will be increased, and the allowable G limits are reduced to +4.0/-2.0. (Those reduced G limits aren't normally a problem for me) The maximum landing weight has not been changed. In Mac McClellan's blog http://macsblog.com/2011/08/when-a-kit-aircraft-is-not-a-kit-aircraft/ he asserts that all changes to a kit make each one a one-off. He refers to Dick (Van's) VanGrunsven's article about the engineering that goes into setting the RV-10's gross weight: http://macsblog.com/wp-content/uploads/2011/08/94-99_Handbook_v6.pdf While Van (nor I) dispute that there are airplanes flying around (successfully) with higher gross weights, I'm concerned that I do not have the engineering background to justify any gross weight other than to use what the factory provides. Vans asserts that the built-in engineering margin belongs to the designer and you can't have it. In particular, does the G loading become so low that I'd have to be concerned about turbulence breaking my wings off? I have no idea. Granted, the 360 has a lot of factory options. And I agree that no two are probably alike. But I feel a little better while building mine that I'm sticking to something that a real aeronautical engineer designed and approved. (That is meant that *I* do not have the aeronautical engineering skills to make that determination, I can't speak for anyone else) Thoughts? I have no idea what mine will weigh when finished. But I know the girlfriend likes to pack heavy. Might be time to look for a 4-place... -Rob (Lancair 360 MKII, 15% completed)