Read it and weep.....the 65% Critical Nr Number shows up in an actual flight test.
The caution that the report results should not be applied to other aircraft or conditions reminds us of what has been said.
IAS parameters were limited to 25-80 Knots....and airspeeds outside that range resulted in excessive vibrations.
http://ntrs.nasa.gov/archive/nasa/ca...1969019854.pdf