Plots of power and thrust for a typical aircraft, the two related by P=TV.  The minima yield the sped for maximum endurance and the tangents for maximum range. Speed is normalised to that of the power minimum.
<a href="//commons.wikimedia.org/wiki/User:TSRL" title="User:TSRL">TSRL</a>
CC BY-SA 3.0
<span class="int-own-work" lang="en">Own work</span>