On 24 Feb 2005 00:11:50 -0800, Mark James Boyd wrote:

I was thinking recently about ground loops and flaperons and
adverse yaw and crosswinds. I can understand how
one needs a rudder for sideslips, but beyond that:

Is anyone making a modern competition glider without adverse yaw
using frise ailerons?
How about one that had no ailerons but just spoilers for roll?

Frise ailerons are made so that when one aileron goes down and
increases drag, the other aileron going "up" has a drag
edge on the bottom which increases drag on the opposite side
equally. So when the ailerons are deflected, there is
no adverse yaw, only increased drag on both wings equally.

Neat on the Duchess and the Aero Commander (twin engine planes)
but haven't heard of it in competition gliders.
Also haven't heard of rudder-aileron interconnect for gliders.

I have heard that some big jets, perhaps 737 and such, use spoilers
for additional roll authority as well.
And the U-2 was rumored to have twisting trailing edge landing gear,
so landing in a crosswind in a crab was fine.

The aircoupe combined a lot of these features to make a plane without
a rudder.

Have gliders other than the MDM-1 Fox or SZD 22C Mucha
tried frise ailerons?
A friend is building a Carbon Dragon,
which uses flaperons. Although that sounds great (nice speed
range) I wonder about the adverse yaw.

Ok, ok, maybe a frise type settup isn't aerodynamically efficient
(since there is extra drag during each roll in/out) but then again
lots of rudder during a roll isn't that efficient either.
Did some sailplane designer do a bunch of math and conclude
that frise ailerons, or using spoilers only, just wasn't
gonna work for sailplanes? Or has it just not been done generally...

The Mucha 22C took 1st place in the 1958 Standard Class world championships.
(according to the sailplanedirectory).
Was this the last time frise ailerons made a "splash" in gliding?

You answered your own question: Too much drag in a high performance
sailplane which spends quite a lot of its time banked in a turn in
thermals.
What's wrong with using the rudder ?
Cheers, John G.