Helium bubbles used to show bird aerodynamics

Tango Whisky wrote on 3/21/2020 1:37 AM:
Absolutely. On a modern glider, this slope goes through zero at the angle of attack of best L/D (zero lift = minimum drag). Below that speed, the tailplane produces lift, above it produces downward force.

Curiously, that is not (we're told) how the model gliders are trimmed: the tail is
lifting at minimum sink. That seems inefficient to have a small wing producing
lift instead the big wing, with it's lower drag from a larger aspect ratio.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1