Slipping in Turns

I'm wondering if many people hold a mild slip in turns and why they do it.
Please reply to this post if you do this and give your reason(s).

Thanks,
Jim Hendrix

I'm wondering if many people hold a mild slip in turns and why they do it.
Please reply to this post if you do this and give your reason(s).

Thanks,
Jim Hendrix


I do because Dick Johnson, in a talk, convinced me it is both safer and more
aerodynamically efficient. It also seems to make it easier to thermal
precisely.

Larry Pardue 2I

Jim,

There was a thread on this subject a year or two ago, you might want
to search the archives.

The simple aerodynamic answer goes like this: The circle is traced by
the glider's center of gravity, which means that your nose extends
beyond the edge of the circle. To visualize, draw a circle, then draw
a line tangent to it. You can see that the nose and tail of your
fuselage transcribe larger circles. A yaw string forward of the cg
will show a slight slip for a coordinated turn (that is, coordinated
at the cg, or wing). If your yaw string is straight, then you are, in
fact, slightly skidding the turn. This effect also exists at the tail,
requiring you to hold a little bit of rudder into the turn (but not so
much that you straighten out the yaw string). Obviously, the longer
the arm, the greater the effect.

I've tried to observe the difference between the front and rear yaw
strings on a G103, but the canopy edge generates too much turbulence
to mark any clear difference.

For practical purposes, the slip is small (5 to 10 degrees).

Measured with a cad-program, for a turn radius of 30 m, the thread angle
should be 3.6 degrees, if the distance of the thread from cg is 2 m. Tighter
turn, wider angle. How precisely you can keep your thread in a 3-4 degree
angle?

js

"Chris OCallaghan" wrote in message
om...
Jim,

There was a thread on this subject a year or two ago, you might want
to search the archives.

The simple aerodynamic answer goes like this: The circle is traced by
the glider's center of gravity, which means that your nose extends
beyond the edge of the circle. To visualize, draw a circle, then draw
a line tangent to it. You can see that the nose and tail of your
fuselage transcribe larger circles. A yaw string forward of the cg
will show a slight slip for a coordinated turn (that is, coordinated
at the cg, or wing). If your yaw string is straight, then you are, in
fact, slightly skidding the turn. This effect also exists at the tail,
requiring you to hold a little bit of rudder into the turn (but not so
much that you straighten out the yaw string). Obviously, the longer
the arm, the greater the effect.

I've tried to observe the difference between the front and rear yaw
strings on a G103, but the canopy edge generates too much turbulence
to mark any clear difference.

For practical purposes, the slip is small (5 to 10 degrees).

"JS" wrote in message ...
Measured with a cad-program, for a turn radius of 30 m, the thread angle
should be 3.6 degrees, if the distance of the thread from cg is 2 m. Tighter
turn, wider angle. How precisely you can keep your thread in a 3-4 degree
angle?

js

Hello JS -You must be flying a hang glider to be capable of turning a 30 meter radius while thermalling. For a given bank angle, the theoretical turn radius is proportional to the square of the flight velocity. Right?
My unballasted Ventus requires about 48 kts of airspeed when
performing a 45 degree banked thermalling turn. Under those conditions
I calculate my turn radius to be about 204 ft, or 62 meters.
Dick Johnson

I toke a small radius just to show, how tigth the turn must be to get about
5-10 degree angle for thread. With a 60 m radius, the angle of thread is
about 1.7 degrees, if it shows the true slipping angle of the position,
where the thread is located.

Added the asymmetric force of the air to the another side of the glider
while slipping, I doubt if there is any even small advantage to do it. It
coud be vice versa, so that there is some advantage to do skidding, because
then the air forces the glider a bit towards the core.

In either case the effect seems to be very small and question looks like
quite academic. Those opposite vectors might even summarize to absolute zero
anywhere bethween this very small angle...?

js


"Dick Johnson" wrote in message
om...
"JS" wrote in message
...
Measured with a cad-program, for a turn radius of 30 m, the thread angle
should be 3.6 degrees, if the distance of the thread from cg is 2 m.
Tighter
turn, wider angle. How precisely you can keep your thread in a 3-4
degree
angle?

js

Hello JS -You must be flying a hang glider to be capable of turning a 30
meter radius while thermalling. For a given bank angle, the theoretical turn
radius is proportional to the square of the flight velocity. Right?
My unballasted Ventus requires about 48 kts of airspeed when
performing a 45 degree banked thermalling turn. Under those conditions
I calculate my turn radius to be about 204 ft, or 62 meters.
Dick Johnsonto

A better question might be, "which is better, a slight slip or a
slight skid?" Since we try to hold the yaw string at 0 degrees in
wings level flight, holding it at 5 to 10 degrees shouldn't be any
more difficult. As others have alluded, there are safety advantages to
holding slip rather than skid in a turn, therefore, it seems
worthwhile to at least make an effort to keep the nose a little
slipped for the sake of the airflow over the wings.

As for the angle of the yaw string, first, there is no one angle. It
will change directly proportionally to increasing bank and inversely
with increasing speed. The position of the yaw string relative to the
cg is significantly different for different models. And as you have
noted, individuals' abilities to distinguish small angles varies. This
is why I suggested a broad range of 5 to 10 degrees, rather than a
single case optimization. 5 degrees is about 2 minutes sweep of the
minute hand of a clock; 10 degrees is not quite 4. These are
discernable and useful.

"JS" wrote in message ...
Measured with a cad-program, for a turn radius of 30 m, the thread angle
should be 3.6 degrees, if the distance of the thread from cg is 2 m. Tighter
turn, wider angle. How precisely you can keep your thread in a 3-4 degree
angle?

js

"Chris OCallaghan" wrote in message
om...
Jim,

There was a thread on this subject a year or two ago, you might want
to search the archives.

The simple aerodynamic answer goes like this: The circle is traced by
the glider's center of gravity, which means that your nose extends
beyond the edge of the circle. To visualize, draw a circle, then draw
a line tangent to it. You can see that the nose and tail of your
fuselage transcribe larger circles. A yaw string forward of the cg
will show a slight slip for a coordinated turn (that is, coordinated
at the cg, or wing). If your yaw string is straight, then you are, in
fact, slightly skidding the turn. This effect also exists at the tail,
requiring you to hold a little bit of rudder into the turn (but not so
much that you straighten out the yaw string). Obviously, the longer
the arm, the greater the effect.

I've tried to observe the difference between the front and rear yaw
strings on a G103, but the canopy edge generates too much turbulence
to mark any clear difference.

For practical purposes, the slip is small (5 to 10 degrees).

Jim Hendrix wrote:
I'm wondering if many people hold a mild slip in turns and why they do it.
Please reply to this post if you do this and give your reason(s).

Thanks,
Jim Hendrix


Yes many do, me included. In the gliders I've tried it in, Grob 103
Ventus b and Mosquito, I find I have much better pitch control when
turning steeply e.g. 45 deg. People argue the aerodynamic pros and
cons. I figure if I can stay in a tight thermal more easily, or a more
powerful core, I'll climb faster. Works for me.

Cheers,
Shawn

I'm anyway too stupid to fly coordinated, so I choose to better slip into
the thermal than skidding out of it :-)

--
Bert Willing

ASW20 "TW"


"Shawn Curry" a écrit dans le message de
hlink.net...
Jim Hendrix wrote:
I'm wondering if many people hold a mild slip in turns and why they do
it.
Please reply to this post if you do this and give your reason(s).

Thanks,
Jim Hendrix


Yes many do, me included. In the gliders I've tried it in, Grob 103
Ventus b and Mosquito, I find I have much better pitch control when
turning steeply e.g. 45 deg. People argue the aerodynamic pros and
cons. I figure if I can stay in a tight thermal more easily, or a more
powerful core, I'll climb faster. Works for me.

Cheers,
Shawn

What about this: when I press another pedal slowly down an keep it there,
holding wings level, plane begins to fly round a point at the noses and
pressed pedals side. Thread shows I am skidding to opposite side. I could
allmost thermal like this, holding wings in level.

So why shoud I slip into thermal, becouse skidding out of it turns the plane
into the direction of thermals core.

Complicated...

js


"Bert Willing" wrote in
message ...
I'm anyway too stupid to fly coordinated, so I choose to better slip into
the thermal than skidding out of it :-)

--
Bert Willing