Winglet performance

"Berry" wrote in message ...
In article ,
BruceGreeff wrote:

When asked what airfoil he used on his HP winglets, Dick Schreder
replied "I use the ROF-POB airfoil. Questioned further he elaborated
"Round on front-pointy on back".


I am aware of a lot of Schreder sailplanes with winglets; however, I haven't come across any with Dick's plywood slabs described above bolted to the wingtip rib. Almost all the HP/RS-15 winglets are based on (copies of) the winglets described in the Free Flight page 6 article by Peter Masak.(http://www.wgc.mb.ca/sac/freeflight/92_02.pdf)

HP pilots note that winglets definitely improve aileron effectiveness resulting in higher roll rates.

Wayne
http://www.soaridaho.com/Schreder

Just to throw my voice into the mix - my DG-300 was retrofitted with
(factory-supplied) winglets...

The difference in L/D is so small with most winglets, that even if its
working correctly it would be hard to notice... Like others have said
- its "almost as good as" an equal improvement in span. What's the L/
D difference between a good 15-meter ship and a good 16-meter ship?
Very little.

However, I do notice an improvement in slow-speed handling with my
winglets on. This is where I believe a lot of people derive benefit
from them: Improved airflow over the wing at slow speeds and while
turning can directly translate into better thermalling performance,
both in reduced drag and in improved aileron control/authority.

--Noel

On 2/22/2011 12:11 PM, noel.wade wrote:
Just to throw my voice into the mix - my DG-300 was retrofitted with
(factory-supplied) winglets...

The difference in L/D is so small with most winglets, that even if its
working correctly it would be hard to notice... Like others have said
- its "almost as good as" an equal improvement in span. What's the L/
D difference between a good 15-meter ship and a good 16-meter ship?
Very little.

No one can notice the difference between 40 and 42 in L/D. You might be
able to measure it with very careful measurements, but "notice" it? No.

However, I do notice an improvement in slow-speed handling with my
winglets on. This is where I believe a lot of people derive benefit
from them: Improved airflow over the wing at slow speeds and while
turning can directly translate into better thermalling performance,
both in reduced drag and in improved aileron control/authority.

Noel echos my experience, and it's not just in flight, but on the ground
roll, too. It makes a glider less likely to drop a wing at the start of
takeoff, or near the end of the rollout.

I retrofitted factory winglets to my ASH 26E. Besides the above, I could
see (and confirm with photographs), that the wingtips were higher in
flight with the winglets than without, evidence that the winglets had
shifted the lift distribution outwards. I have no idea if the cruise L/D
was changed.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)

Greenwell wrote:
However, I do notice an improvement in slow-speed handling with my
winglets on.

Noel echos my experience, and it's not just in flight, but on the ground

The main benefit of winglets, especially for the older among us, is that
we don't have to bow that much to pick up the wing.

On 2/23/2011 1:59 AM, John Smith wrote:
Greenwell wrote:
However, I do notice an improvement in slow-speed handling with my
winglets on.

Noel echos my experience, and it's not just in flight, but on the ground

The main benefit of winglets, especially for the older among us, is that
we don't have to bow that much to pick up the wing.

And, you can put a tire on it and it won't slip off in the wind! Not
that I'm suggesting that is a good practice...

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)

On Feb 23, 1:59*am, John Smith wrote:
Greenwell wrote:
However, I do notice an improvement in slow-speed handling with my
winglets on.
Noel echos my experience, and it's not just in flight, but on the ground

The main benefit of winglets, especially for the older among us, is that
we don't have to bow that much to pick up the wing.

and to the younger, they look bitchin'

Brad

On Feb 23, 3:27*pm, Brad wrote:
On Feb 23, 1:59*am, John Smith wrote:

Greenwell wrote:
However, I do notice an improvement in slow-speed handling with my
winglets on.
Noel echos my experience, and it's not just in flight, but on the ground

The main benefit of winglets, especially for the older among us, is that
we don't have to bow that much to pick up the wing.

and to the younger, they look bitchin'

Brad

Bah! Draglets!

Just stick your toe under the (beautifully unencumbered) wingtip and
lift your foot - voila, no bending required at all...

Anyway, if winglets were so great, why don't they have their own
winglets? - ad infinitum!

Kirk
66

At 13:11 24 February 2011, kirk.stant wrote:
On Feb 23, 3:27=A0pm, Brad wrote:
On Feb 23, 1:59=A0am, John Smith wrote:

Greenwell wrote:
However, I do notice an improvement in slow-speed handling with
my
winglets on.
Noel echos my experience, and it's not just in flight, but on the
gro=
und

The main benefit of winglets, especially for the older among us, is
tha=
t
we don't have to bow that much to pick up the wing.

and to the younger, they look bitchin'

Brad

Bah! Draglets!

Just stick your toe under the (beautifully unencumbered) wingtip and
lift your foot - voila, no bending required at all...

Anyway, if winglets were so great, why don't they have their own
winglets? - ad infinitum!

Kirk
66




you want winglets on winglets (wingwinglets? wing2lets?) ... Stanford got
there first :-)

http://aero.stanford.edu/CWing.html

Doug

On Feb 24, 8:11*am, "kirk.stant" wrote:
On Feb 23, 3:27*pm, Brad wrote:

On Feb 23, 1:59*am, John Smith wrote:

Greenwell wrote:
However, I do notice an improvement in slow-speed handling with my
winglets on.
Noel echos my experience, and it's not just in flight, but on the ground

The main benefit of winglets, especially for the older among us, is that
we don't have to bow that much to pick up the wing.

and to the younger, they look bitchin'

Brad

Bah! Draglets!

Just stick your toe under the (beautifully unencumbered) wingtip and
lift your foot - voila, no bending required at all...

Anyway, if winglets were so great, why don't they have their own
winglets? - ad infinitum!

Kirk
66

The law of diminishing returns.
I sense some closet winglet envy leading to denial.
UH