Thanks for the info, FT, and the challenge to do some more research. Being not unfamiliar with Mr. Bernoulli's Theorem, I apologize for the earlier literary exuberance on my part. Your post sent me scurrying to the internet where my initial and admitted lay research (not being a fluids engineer) suggests this may be a tad more complex than presented. The more research, the more questions. Too much to compress into a short post, but those with equally bent interests may wish to look at:
<a href="http://www.hq.usace.army.mil/cemp/e/Et/efficien.pdf" target="_blank">http://www.hq.usace.army.mil/cemp/e/Et/efficien.pdf</a>
and some of the other academic/engineering sites using duct/friction/airflow as key words.
What intrigues me is the amount of air that goes into the engine - a cylinder bounded by the diameter of the inlet and equal in length to the forward movement of the aircraft. If there are inefficiencies at relatively low CFM, as indicated in the above URL, are they multiplied at very high volumes? Density at altitude is yet another factor. I'll grant you this is edge of the boundary-layer stuff, but there may be something to be learned here, even if it is not mainstream.
BTW, I am unconvinced about the no-download argument, having conducted practical tests and having pondered Newton's Third Law.
On the subject of airflow reversal in turbine engines, especially of the free sort, what of the PWC PT-6, with its 1080 degrees of directional change from free air to exhaust? I have always wondered if the relatively inferior fuel specifics of that engine (despite its many other sterling qualities) was yet another example of the many twists and turns through which gas had to thread itself, as it wended its way around the Gas Generator and Power Turbine. My own facetious theory of the PT6 is that half the power produced by that little engine is because the air is so frigging frustrated, all it wants to do is escape!
Cheers
TR. . <img src="confused.gif" border="0"> <img src="smile.gif" border="0">
[ 25 January 2002: Message edited by: Thermal Runaway ]
[ 25 January 2002: Message edited by: Thermal Runaway ]</p>