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Hello John
I have found the
Mesny's _expression_ on an old university stenciled book where only the data were
given, but some time ago, for purpose of include it in a program, I have
elaborated an empiric _expression_ that approximates
sufficiently these data. That is:
q = ( 1 + .95 d / D )^2 - .22
Best 73 to all Cesare
Hi Paul,
From the
interesting formula given by Cesare, the short answer to your question
appears to be 1/2 inch.
I tried to find out more about Mesny's
_expression_ from the Internet, but it looks like you have to buy the book.
I wonder whether Cesare can be persuaded to tell us the formula that
relates q to D/d? At a guess it appears to be logarithmic.
The second
formula can be simplified to
Reff/Rrf = 1 + (q-1)*sqrt(1-Rdc/Rrf)
When D/d = 9, q = 1 so the second term disappears and Reff = Rrf.
73, John, G4CNN
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