my plans are dated Jan 1990 page 6 of the KR2 plans say "design stress loading is +/- 7 g's at 800 lbs gross" but the specifications on page 3 say the gross weight is 900 lbs.
+/- 7 g @ 800 lbs is equiv to +/- 6.2 @ 900 or +/- 5.7 @ 980 or +/- 5.33 @ 1050 But the KR2S uses a longer wing, which will create larger bending moments at the fuselage and wing attach fittings. The report titled "Structural Properties of the Rand-Robinson KR2S" prepared by Marcy Analytics Corporation states "For the KR-2S, the design ultimate load factor is 6.0, and by extension, the design limit load factor is 4.0." In a later section it pulls numbers from FAR 23, Appendix A for a V-n diagram that is where the -2 load factor is described. -- wesley scott k...@spottedowl.biz ----- Original Message ----- From: "Duncan" <k...@chalksoft.com> To: "Wesley Scott" <k...@spottedowl.biz>; "KRnet" <kr...@mylist.net> Sent: Sunday, August 08, 2004 2:41 PM Subject: Re: Spar strength was Re: KR> KR2S Sport pilot eligible??? > Wesley, > Hi. +4/-2? My plans say +7/-7 @ 800lbs - does this compute to +4/-2 @ > 1050lbs? > > Duncan > ===================================== > At 04:05 a.m. 9/08/2004, you wrote: > > >What g factor are you using for the analysis? RR used +4/-2 as the design > >limit load factors (FAA requires an ultimate load of 1.5x the limit load). > >At a gross weight of 1050 pounds, there is an approximate margin of safety > >of 16% per Bill Marcy's analysis. > > > > >
