Reynolds flying or floating bodies (for airships) according to their speed and the chord of their wings (or their length, for airships). This chord or length is indicated by diagonals, as well as the speed of sound.
<a href="//commons.wikimedia.org/wiki/User:Bernard_de_Go_Mars" title="User:Bernard de Go Mars">Bernard de Go Mars</a>
CC BY-SA 4.0
<span class="int-own-work" lang="en">Own work</span>