polar for unpowered aircraft with weight 2000 kg, wing arae 15 m^2 in atmosphere density 1.2 kg/m^3.  Drag polar 0.017+ 0.075*(Cl-0.1)^2
<a href="//commons.wikimedia.org/wiki/User:TSRL" title="User:TSRL">TSRL</a>
<span class="int-own-work" lang="en">Own work</span>