Andreas Maurer wrote on 2/15/2016 2:17 PM:
On Mon, 15 Feb 2016 07:16:51 -0800, Eric Greenwell
wrote:


Maybe this is intended as joke, but the last thing you want is a very
low L/D "airfoil" like the fuselage involved in providing any lift.


Depends on the type of glider.

An open class ship needs a lot of sideslip while thermalling.

I learned that a long time ago from Uli Schwenk, who told me that he
learned that from a guy named Klaus Holighaus.

Thermalling with the yawstring 30 degrees outwards makes a huge
difference in climb performance. Huge.

Explanation:
The yaw costs a lot of drag due to the "low L/D fuselage" - but it
saves even more drag because you barely need any opposite aileron
anymore, therefore you get a much better lift distribution (and
therefore much less induced drag) on the wing.


One other glider that needs a lot of yaw in a thermal: Arcus.

I agree there are gliders where that drag would be an acceptable
trade-off, but the pilot I was responding to thought it was a "bonus",
and it's clearly not that.

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? 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.


--
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
- "Transponders in Sailplanes - Dec 2014a" also ADS-B, PCAS, Flarm

http://soaringsafety.org/prevention/...anes-2014A.pdf