[Land-speed] OT, but...., Reno Air Race crash 2011 NTSB report

[23weldon]

http://www.ntsb.gov/news/events/2012/reno_nv/index.html

Interesting read.  Especially the sentence under "Probable Cause" that
reads:
"The reduced stiffness was a result of deteriorated locknut inserts that
allowed the trim tab attachment screws to become loose and to initiate
fatigue cracking in one screw sometime before the accident flight."
Most of us if we use elastic stop nuts or similar plastic thread lockers we
don't use them on prestressed alloy bolts.   Rather they get mostly used on
suspension or control bolts that don't have fatigue issues.  But the more we
push our limits the more likely we are to encounter such things in our LSR
machines.
I'm going to put my mechanical engineer's hat on for a moment and suggest
you creative guys who build really fast machines get a little familiar with
the subject of fastener fatigue and prestressing (by torquing) and the
meaning of the "modified Goodman diagram" (google this phrase). "metal
fatigue" and "metal endurance limit".  Not a lot of math there; but a basic
understanding or aluminum and steel metallurgy will help.
Ed Weldon