Depending on what your doing with the Prandtl-Glauert correction, you can vary velocity for example as much as ~75 mph TAS over measured results or even more depending on the design specifics.

The basic correction agreement between calculated and wind tunnel data for a tailess DC-9 for example shows the Prandtl-Glauert correction to be some 66 mph TAS pessimestic over measured results.

Got a link?

Ah. Not quite what I expected.

Very good link - Thx

Most of the text seems to be extracted from an abridged version of the book written by the father of modern aerodynamics at NACA/NASA in the early 50's. This book is available on Amazon at such a cheap price that's it's a shame that it's not part of the basic every engineering student shld have right on his desk. No, most of the time you have to buy expensive book written by Mr Professor or one of his collegue with only a fraction of the knowledge available inside. I have alrdy given the title somewhere.

Ok just that to say that Crump is really helping the comunity to step forwrd. He has is own style, that's for sure, but ehhh, why do you think some of us are bidding so much time writing here ?

And for all the aficianados of obscurantism that want to raise the 1940 RAF in lieu of a new religion may I remind you that this fight was all about putting an end to obscurantism . You seems to forgot that with your arguments hammered contently in every forum despite the fact tht Britain in those times was the bright and best example of a democracy at war struggling with all her might to survive - making me really thinking of - Oh funny is that - to France at the time of the Napoleon's war ! (yeah I know you just fall of your chair ;-D ) - or Israel in the early times - and Israel strategy was very much inspired by the Britain example )

However, I would remind to all that all those tearing depate for who is the real pilot and who is not, this sentence from a test pilot : None pilots will ever do a a good engineer and vice versa. You don't have to expect the same from the ones that are proud to put frwrd their"pants" when other swear only by their brains.

I think we need some kind of PETA's campaign on this forum with some kind of slogans like " Free the Crumpp" or whatever because the constant firing on him look like very much the beating of baby seals.

just my two cents.

~S to all !