..ecco qua, ho rintracciato il post (non era un articolo) di Mark Drela su RCGroups dove parla degli svantaggi del differenziale in termica:
markdrela
Mar 26, 2006, 05:43 PM
"The fundamental disadvantage of aileron differential is that uses added profile drag to generate a yaw moment. A rudder uses lift instead, and hence it can overcome adverse yaw at a significantly lower energy cost -- for a given yaw moment, the induced drag on the typical rudder is far less than the net added profile drag on the upward-deflected aileron. The larger the vertical span of the rudder, the better it looks in this regard. All this is may not be an issue on most powerplanes, but it is on gliders.
The second drawback of aileron differential is that it does indeed alter the pitch trim. This noticably interferes with precise pitch control while thermalling.
I no longer use any significant aileron differential on my gliders, primarily to get rid of the pitching effect. The only exception is during winch launch, where I use 100% differential. Here the reason is avoiding tip stall rather than overcoming adverse yaw."
Per chi è interessato, qui c'è l'intera discussione
http://www.rcgroups.com/forums/showthread.php?t=496506
Per finire, come si usa il direzionale in termica, sempre di Drela:
http://polecataero.com/articles/usin...thermal-flying
Mark
...ma non Drela <_<