Seat Belt fun

Thanks Mike and Alan for comments about the seat belt. This is very valuable experience for you guys to share. In light of your feedback, I'm going to make sure to change or at least seriously evaluate how easily the belt opens before any flying. I can find a replacement lap belt with the push button type buckle with the same steel end plates, so I figure installing this belt won't be a backward step.

The original location Sandlin used was to loop the webbing material aft of the rear seat tube, just forward of the structural wing cable/strut attach point. Since I'm using the steel plate style with a 5/16" bolt, this location doesn't work exactly. The belt would rub on the end of the lower seat tube. My option is to move the belt to frame attach point forward.

Trying to figure out where to mount the lap belt, I have turned to aircraft standards, which are less descriptive for this mounting location than I hoped. From my student club days, I know the Formula SAE car competitions have stringent requirements on the students' creations, so I consulted the 2009 rules: http://www.sae.org/students/mbrules.pdf. Section 33.3 covers lap belt and in particular Figure 9 (shown here).

The Formula SAE regulations give a minimum of 45deg to a maximum of 65deg for the lap belt centerline to body angle. I clamped my belt in my proposed location and took a side-on self-portrait to compare the angle. I'm relatively happy with this angle, maybe even fine sliding the bolt forward a bit, and figure my updated seat will put my behind in a similar location for the belt angle. I'll probably sit on this (pun intended!) for a few days and pull out my 5/16" drill bit.