Posted by wunhuanglo [ 68.222.55.80 ] on August 04, 2006 at 21:46:13:

In Reply to: Re: Martin, I agree totally!!!! posted by Martin on August 04, 2006 at 11:34:11:

I swear this is true. I go to the FEA gunius - 1978, IBM mainframe, MSC Nastran - tell him I need the 1G gravity sag at the center of a three-point edge supported, circular, 3 foot diameter fused silica mirror, three inches thick, lightweighted fom the back with 1-1/2" square pockets on a more-or-less regular grid, leaving about a 1/2" faceplate when polished.

3 or 4 weeks later I receive about 5 inches of green&white - output section says the center deflection is 3 INCHES!!!

I go to wonderboy and say "You think there might be something wrong here?

Wonderboy says (indignantly) "Can't be, that's what the model says."

Wonderboy's boss (who refused to talk to him) was a Mercury/Gemini era structural guy. He and his buddy had (more than 1) editions of Rourke that they had hand corrected over the years, doing the derivations independently and comparing them to Rourke and marking up the text. For fun.

There were some guys working in the old days.

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