On Tue, 16 Feb 2016 19:58:42 -0800, Eric Greenwell
wrote:



I am curious about why a 20 meter glider would need a lot of yaw to
climb well, when my 18 meter ASH 26E hardly needs any. 20 or 30 degrees
would be a poor choice for the 26E, but you say an Arcus needs that
much?


I guess it's a question of aircraft geometry and cannot be predicted
precisely.

I was surprised how nasty the Arcus was thermalling with the yaw
string centered (some of the PICs I instructed needed full aileron
input and really hard work to keep it in the turn) and how nice it
flew with significant opposite rudder.

I didn't expect that, especially since the Duo Dicus with its very
similar wing geometry doesn't show this behaviour.

Dihedral does not seem to be an important factor: The Arcus with its
huge dihedral behaves similar to the AS 22-2 that has too little
dihedral (and needs nearly full opposite aileron if you turn with the
yaw string centered) and no winglets.


Is that part of the operating manual for the glider? I would
expect the inner winglet to be stalled, and the outer winglet to be
producing outward lift.

I don't think so, but I haven't read the Arcus POH that carefully I
have to admit.

I am pretty sure that the outer winglet is the one that is stalled
(camber is pointing towards the fuselage, therefore reducing stall
AOA).