Originally Posted by PBL
Originally Posted by Anderson, Introduction to Flight, Section 1.16.2 ....
I wrote that? So I did. It's section 6.12.1, p448.
Originally Posted by HN39
Anderson apparently makes the simplifying assumption that power-specific fuel consumption is constant, which in practice it is not
He discusses these issues in depth.
The issue is not whether and how one makes simplifying assumptions, which are part and practice of doing any engineering whatsoever, but how sensitive your answers are to those assumptions.
Given typical data on engines, it seems to me that the quadratic effect of velocity on the aerodynamic calculations generally overwhelms the rather linear (with low slope) relation of velocity to available thrust. But I am open to being otherwise persuaded if someone can produce data to say so.
PBL