Steven:
This example was sourced from Suhl as were all others I have seen. Right off the top of my head me thinks I would have gleaned info from the patent, Klup's Drilling page 47, DGJ Volume 9, Issue 1(Spring 1998) at page 151 and I want to think a GGCA publication to have info but I am not certain. I think Dr. Martin Moog to be one of the authorities. If anyone doesn't have the DGJ issue and wants a brief, I may be able to put something together. Also I think it was Krieghoff to have offered example with short tubes.
Kind Regards,
Raimey
rse
