The test exercise was originally intended to verify the design for the Wing
Attach Fittings (WAF). In the picture for testing the KR-2 spar, the jack
was placed at the end of the inner spar section. that placed a point load
there. Loading of a KR-2 spar in flight has a distributed force. The test
method had no measurement for the actual forces being applied; might have
been equivalent to 6 G, maybe 20 G, totally unknown. At the time the talk
was: Since we have no instrumentation, just break it and see where it
breaks. Due to the test setup the web plywood was subjected to shear force,
not the vertical force that was originally designed for. Also note the
failed glue joints for the vertical blocks; another indication of shear
loading and poor workmanship. The anhedral of the outer wing spar in the
first picture definitely indicates the shear loading..
Sid Wood
Tri-gear KR-2 ex-N6242
California, MD, USA
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It would seem to me the force on the web is more in shear or tension
than compression as evidenced in the photo. The web appears "pulled
apart", not compressed.
http://www.krnet.org/mvn2008/080921265.jpg
http://www.krnet.org/mvn2008/080921282.jpg
What am I missing?
Larry Flesner
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