Flaps VS Airbrakes/Spoilers

[Walt Connelly]

Well about half of the posts re flaps only gliders made me feel positive about the possibility of finding a glider with flaps only, and the other half made me feel just the opposite. I guess you could dump flaps on final rather quickly if your speed was above stall for all ranges of the flaps as they came up but the purpose of flaps is to create more lift allowing for a lower approach speed or am I mistaken? Apparently beyond a certain point the flaps cease to provide lift and are only a drag device. It would make sense that a quick move from the drag area back to the maximum deflection for lift could be accomplished quickly with little problem.

I guess the best option is for a glider with both flaps and spoilers/airbrakes but I don't think there are a lot of those out there. Sometimes too many opinions from too many people are a bad thing.

Walt

[mike]

On Aug 15, 2:57*pm, Walt Connelly <Walt.Connelly.
> wrote:
> Well about half of the posts re flaps only gliders made me feel positive
> about the possibility of finding a glider with flaps only, and the other
> half made me feel just the opposite. *I guess you could dump flaps on
> final rather quickly if your speed was above stall for all ranges of the
> flaps as they came up but the purpose of flaps is to create more lift
> allowing for a lower approach speed or am I mistaken? *Apparently beyond
> a certain point the flaps cease to provide lift and are only a drag
> device. *It would make sense that a quick move from the drag area back
> to the maximum deflection for lift could be accomplished quickly with
> little problem.
>
> I guess the best option is for a glider with both flaps and
> spoilers/airbrakes but I don't think there are a lot of those out there.
> Sometimes too many opinions from too many people are a bad thing.
>
> Walt
>
> --
> Walt Connelly

Check out the Mini Nimbus, Mosquito and early Ventus.

[BobW]

On 8/15/2011 2:57 PM, Walt Connelly wrote:
> Well about half of the posts re flaps only gliders made me feel positive
> about the possibility of finding a glider with flaps only, and the other
> half made me feel just the opposite. I guess you could dump flaps on
> final rather quickly if your speed was above stall for all ranges of the
> flaps as they came up but the purpose of flaps is to create more lift
> allowing for a lower approach speed or am I mistaken?

The 'purpose of flaps' - Is this where philosophy enters the aerodynamic world
definable by flaps' effect on a glider's polar? To me, viewed most generally,
the purpose of (large deflection landing) flaps is identical to the purpose of
spoilers, i.e. to ease Joe Glider Pilot's task of safely making a landing
pattern into 'glider-size' fields...different ways to skin the ease/safety cat.

Beyond that, both options come with their pros & cons. Again to my way of
thinking, it would be a 'glider shame' to wantonly disregard/not use the
flap-related effect of increasing the max lift inherent in the use of the
simply-hinged flaps used on (say) every 15-meter FAI-class ship around and
most >15-meter span ships. That's true even if the ship uses its flaps 'only'
for optimizing the drag bucket of the airfoil in cruise (i.e. they don't
deflect much beyond ~20-degrees). Stated another way, if Joe Glider Pilot's
ship has (small deflection, 'intended for cruise optimization-only') flaps, in
conjunction with intended-for-landing spoilers, why *wouldn't* JGP go to max
positive deflection flaps before then using spoilers for primary glidepath
control? He still would (could) obtain a theoretical lower touchdown speed
benefit contrasted to not using the flaps.

Where I'm headed with this is, one can reasonably conclude the 'purpose of
flaps' is whatever JGP decides, within their aerodynamic capabilities. You've
noted above, one possible purpose...and others have (and probably will again!)
note this particular purpose comes with its own safety-based 'recommended user
guidelines!' In other words, there's nothing about having (only) large
deflection landing flaps that *insists* one make the whole approach below the
flaps-off stalling speed. I generally did so only under absolutely benign
conditions, otherwise until 'somewhere around' flare altitude keeping my speed
at or above the flaps-off stall speed, less from fear of 'falling out of the
sky like a brick' should I (for whatever reason) instantaneously dump the
flaps, and more because it simply provides a larger margin (margins being good
in my book). However, in any pattern conditions that I thought safely
permitted, I also sought to minimize my touchdown speed (whether on or off
airport) by *using* the extra lift inherent with flaps to minimize my
*touchdown* speed...easiest on the the equipment, if nothing else.

Apparently beyond
> a certain point the flaps cease to provide lift and are only a drag
> device.

"Roger that...and folks will probably 'O-beer-thirty' argue if that point is
30-degrees, 45-degrees, or more." Pick whatever number you like for now!

It would make sense that a quick move from the drag area back
> to the maximum deflection for lift could be accomplished quickly with
> little problem.

....and beyond, if you have the height margin and hand-eye skills...

>
> I guess the best option is for a glider with both flaps and
> spoilers/airbrakes but I don't think there are a lot of those out there.

Only the AS W-20A in the large deflection w. spoiler field that I know of, but
lotsa designs with small-deflection flaps with spoilers. And, of course, the
'don't fit precisely into either category' ships like Mosquito, Vega, Mini
Nimbii, early Ventii, etc., which have their own devils in their own details!
Such fun!!!

> Sometimes too many opinions from too many people are a bad thing.
>
Heh!

Regards,
Bob W.

[Eric Greenwell[_4_]]

On 8/15/2011 1:57 PM, Walt Connelly wrote:

> I guess the best option is for a glider with both flaps and
> spoilers/airbrakes but I don't think there are a lot of those out there.
> Sometimes too many opinions from too many people are a bad thing.

There are lots and lots of them out there! Starting with the ASW 20, all
Schleicher flapped gliders have had "high deflection" landing flaps and
spoilers. ASW 20, ASW 22, ASH 25, ASH 26, ASW 27, ASG 29, and so on.

"High deflection" ranged from 40 degrees to 60 degrees. None of them had
full deflection flaps.

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

[[email protected]]

On Aug 15, 4:57*pm, Walt Connelly <Walt.Connelly.
> wrote:
> Well about half of the posts re flaps only gliders made me feel positive
> about the possibility of finding a glider with flaps only, and the other
> half made me feel just the opposite. *I guess you could dump flaps on
> final rather quickly if your speed was above stall for all ranges of the
> flaps as they came up but the purpose of flaps is to create more lift
> allowing for a lower approach speed or am I mistaken? *Apparently beyond
> a certain point the flaps cease to provide lift and are only a drag
> device. *It would make sense that a quick move from the drag area back
> to the maximum deflection for lift could be accomplished quickly with
> little problem.
>
> I guess the best option is for a glider with both flaps and
> spoilers/airbrakes but I don't think there are a lot of those out there.
> Sometimes too many opinions from too many people are a bad thing.
>
> Walt
>
> --
> Walt Connelly

Landing flaps are quite effective in many ships and really effective
in a few.
Really effective examples: HP series, Concept 70, PIK 20- all are
flaps only
In these ships, you usually don't put full flap in till you have the
field made with margin. Then, if high, just put the nose down a bit
more and down they come. Because they are so effective, there is
rarely any reason to raise them again because you are plenty high.
Flare needs to be soon enough to begin to bleed speed a bit before
going into ground effect to reduce floating down the airport.
I once landed my PIK-20 in a football field over the goal post.
Most effective: ASW-20 early before B and C. Flaps plus spoilers.
Steep approach, no speed build up , min float in flare. I landed my 20
over the goal post and stopped with lots to spare.
"Not quite like 20"- 20B and C, ASH-26, ASW-27, ASG-29. Excellent, but
go around the goal post .
Really effective- 1-35. Around the goal post
Others- The Glasflugel and SH gliders with trailing edge flap brakes
also come down quite well. One benefit is that they are intuitive to
use and easy to transition into.
There is no reason to be afraid of flaps only ship. That said, you
must get some good prep and training to learn how to do it right and
that does NOT come from RAS posts. There is a lot of bad info that is
hard to weed out.
FWIW
UH

[Blake Seese]

On Aug 15, 2:57*pm, Walt Connelly <Walt.Connelly.
> wrote:
> Well about half of the posts re flaps only gliders made me feel positive
> about the possibility of finding a glider with flaps only, and the other
> half made me feel just the opposite. *I guess you could dump flaps on
> final rather quickly if your speed was above stall for all ranges of the
> flaps as they came up but the purpose of flaps is to create more lift
> allowing for a lower approach speed or am I mistaken? *Apparently beyond
> a certain point the flaps cease to provide lift and are only a drag
> device. *It would make sense that a quick move from the drag area back
> to the maximum deflection for lift could be accomplished quickly with
> little problem.
>
> I guess the best option is for a glider with both flaps and
> spoilers/airbrakes but I don't think there are a lot of those out there.
> Sometimes too many opinions from too many people are a bad thing.
>
> Walt
>
> --
> Walt Connelly

I have been flying a Laister LP-15 Nugget for about three years now
and I love the glider as well as the flap system. On the Nugget, the
flaps are super simple, working more like spoilers in terms of
function. One caution on flapped ships is that some are too complex
and make things tougher while landing. I'm sure that once a pilot is
dialed into what ever he or she is flying it becomes second nature
though.

[BruceGreeff]

Get a Kestrel and have both... (and a drag chute for good measure)

On 2011/08/16 3:00 PM, Blake Seese wrote:
> On Aug 15, 2:57 pm, Walt Connelly<Walt.Connelly.
> > wrote:
>> Well about half of the posts re flaps only gliders made me feel positive
>> about the possibility of finding a glider with flaps only, and the other
>> half made me feel just the opposite. I guess you could dump flaps on
>> final rather quickly if your speed was above stall for all ranges of the
>> flaps as they came up but the purpose of flaps is to create more lift
>> allowing for a lower approach speed or am I mistaken? Apparently beyond
>> a certain point the flaps cease to provide lift and are only a drag
>> device. It would make sense that a quick move from the drag area back
>> to the maximum deflection for lift could be accomplished quickly with
>> little problem.
>>
>> I guess the best option is for a glider with both flaps and
>> spoilers/airbrakes but I don't think there are a lot of those out there.
>> Sometimes too many opinions from too many people are a bad thing.
>>
>> Walt
>>
>> --
>> Walt Connelly
>
> I have been flying a Laister LP-15 Nugget for about three years now
> and I love the glider as well as the flap system. On the Nugget, the
> flaps are super simple, working more like spoilers in terms of
> function. One caution on flapped ships is that some are too complex
> and make things tougher while landing. I'm sure that once a pilot is
> dialed into what ever he or she is flying it becomes second nature
> though.

--
Bruce Greeff
T59D #1771 & Std Cirrus #57

[T8]

On Aug 16, 8:51*am, wrote:

> There is no reason to be afraid of flaps only ship. That said, you
> must get some good prep and training to learn how to do it right and
> that does NOT come from RAS posts. There is a lot of bad info that is
> hard to weed out.
> FWIW
> UH

Agreed. On RAS even the normally sane, competent, always-within-his-
limits UH starts telling stories of landing over and between goal
posts.

:-).

-T8

[Wayne Paul]

Here are a few links that can be used as guides to flying flaps-only ships.
http://www.soaridaho.com/Schreder/Large-span_flaps.html
http://www.soaridaho.com/Schreder/Stories/Preparing_for_first_HP_flight.htm
http://www.soaridaho.com/Schreder/Stories/Schreder_on_Flaps.htm
http://www.soaridaho.com/Schreder/HP-11/N631H/TJ_First_Flight.html

I know this is more information then you really want to know. Sorry about
that!

Wayne
HP-14 "6F"
http://tinyurl.com/N990-6F



"T8" wrote in message
...

On Aug 16, 8:51 am, wrote:

> There is no reason to be afraid of flaps only ship. That said, you
> must get some good prep and training to learn how to do it right and
> that does NOT come from RAS posts. There is a lot of bad info that is
> hard to weed out.
> FWIW
> UH

Agreed. On RAS even the normally sane, competent, always-within-his-
limits UH starts telling stories of landing over and between goal
posts.

:-).

-T8

[SF]

On Aug 15, 4:57*pm, Walt Connelly <Walt.Connelly.
> wrote:
> Well about half of the posts re flaps only gliders made me feel positive
> about the possibility of finding a glider with flaps only, and the other
> half made me feel just the opposite. *I guess you could dump flaps on
> final rather quickly if your speed was above stall for all ranges of the
> flaps as they came up but the purpose of flaps is to create more lift
> allowing for a lower approach speed or am I mistaken? *Apparently beyond
> a certain point the flaps cease to provide lift and are only a drag
> device. *It would make sense that a quick move from the drag area back
> to the maximum deflection for lift could be accomplished quickly with
> little problem.
>
> I guess the best option is for a glider with both flaps and
> spoilers/airbrakes but I don't think there are a lot of those out there.
> Sometimes too many opinions from too many people are a bad thing.
>
> Walt
>
> --
> Walt Connelly

My personal favorite get the glider down right now device is a drogue
chute. My Open Cirrus had one in the bottom of the rudder, and the
one time I really needed it on a landout, it worked like a charm. I
practiced with it once and deployed it from 800 FT over the numbers at
SPA, the glider was on the ground and stopped between the vasi's. You
have to put the nose over rather smartly to keep the chute from
pulling the glider into a stall, but man it brings it down in a hurry.

The Open Cirrus I used to own is up for sale again, so for a nominal
fee, you too can have a drouge chute equiped glider.


SF

[Walt Connelly]

Agreed. On RAS even the normally sane, competent, always-within-his-
limits UH starts telling stories of landing over and between goal
posts.

:-).

-T8[/QUOTE]

I have landed on a football field but it was after falling off the roof of the gymnasium.

Walt

[toad]

On Aug 15, 10:55*pm, BobW > wrote:
>
> The 'purpose of flaps' - Is this where philosophy enters the aerodynamic world
> definable by flaps' effect on a glider's polar?
....
> Where I'm headed with this is, one can reasonably conclude the 'purpose of
> flaps' is whatever JGP decides, within their aerodynamic capabilities. ....

Joe Pilot didn't put the flaps there, Bob the designer did. He had a
"purpose", which was probably to lower the stall speed and thus the
approach speed and all the other good things that come from that.

[[email protected]]

On Aug 16, 10:26*pm, toad > wrote:
> On Aug 15, 10:55*pm, BobW > wrote:
>
>
>
> > The 'purpose of flaps' - Is this where philosophy enters the aerodynamic world
> > definable by flaps' effect on a glider's polar?
> ...
> > Where I'm headed with this is, one can reasonably conclude the 'purpose of
> > flaps' is whatever JGP decides, within their aerodynamic capabilities. ....
>
> Joe Pilot didn't put the flaps there, Bob the designer did. *He had a
> "purpose", which was probably to lower the stall speed and thus the
> approach speed and all the other good things that come from that.

I kind of disagree.
From my experience, the benefit of "real" landing flaps is very high
drag such that speed increases only slightly when approach is
steepened and drops off quickly during round out and landing.
They also have the very positive effect of reducing the angle of
attack at the tip, giving much better roll response. Look at a '20 in
full "crow" mode and the tips almost look like they are bending down
relative to inboard part of the wing.
My View FWIW.
UH
(Don't try what I've done at home)

[Eric Greenwell[_4_]]

On 8/17/2011 5:47 AM, wrote:

>> Joe Pilot didn't put the flaps there, Bob the designer did. He had a
>> "purpose", which was probably to lower the stall speed and thus the
>> approach speed and all the other good things that come from that.
>
> I kind of disagree.
> From my experience, the benefit of "real" landing flaps is very high
> drag such that speed increases only slightly when approach is
> steepened and drops off quickly during round out and landing.
> They also have the very positive effect of reducing the angle of
> attack at the tip, giving much better roll response. Look at a '20 in
> full "crow" mode and the tips almost look like they are bending down
> relative to inboard part of the wing.

Not only do they look like it, they are, in fact, bent down a bit. I saw
that on my ASW 20 C, and I see it on my ASH 26 E.

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

[toad]

On Aug 17, 8:47*am, wrote:
> On Aug 16, 10:26*pm, toad > wrote:
>
> > On Aug 15, 10:55*pm, BobW > wrote:
>
> > > The 'purpose of flaps' - Is this where philosophy enters the aerodynamic world
> > > definable by flaps' effect on a glider's polar?
> > ...
> > > Where I'm headed with this is, one can reasonably conclude the 'purpose of
> > > flaps' is whatever JGP decides, within their aerodynamic capabilities.. ...
>
> > Joe Pilot didn't put the flaps there, Bob the designer did. *He had a
> > "purpose", which was probably to lower the stall speed and thus the
> > approach speed and all the other good things that come from that.
>
> I kind of disagree.
> From my experience, the benefit of "real" landing flaps is very high
> drag such that speed increases only slightly when approach is
> steepened and drops off quickly during round out and landing.
> They also have the very positive effect of reducing the angle of
> attack at the tip, giving much better roll response. Look at a '20 in
> full "crow" mode and the tips almost look like they are bending down
> relative to inboard part of the wing.
> My View FWIW.
> *UH
> (Don't try what I've done at home)

I actually kind of agree with you. The purpose of the initial
deflection is lift increase/stall speed decrease. By increasing the
flap deflection available to the "real landing flap" range, the
designer got the high drag/glide-slope control feature without adding
a second system. Obviously some designers have chosen having 2
systems instead.

If all the designer wanted was the drag, he would have used a drag
device. IMHO.

Todd

[Wayne Paul]

The "Flap-only" system appear most often on homebuilt sailplanes. (Schreder
series, BG-12-16, etc) I am sure the designers realized that simplifying
wing construction was one of the advantages of the flaps-only system.

BTW, I don't use the flaps to fly a lower my approach speed. I use them for
the massive amount of drag that they produce.

Wayne
HP-14 "6F"
http://tinyrul.com/N990-6F


"toad" wrote in message
...

On Aug 15, 10:55 pm, BobW > wrote:
>
> The 'purpose of flaps' - Is this where philosophy enters the aerodynamic
> world
> definable by flaps' effect on a glider's polar?
....
> Where I'm headed with this is, one can reasonably conclude the 'purpose of
> flaps' is whatever JGP decides, within their aerodynamic capabilities. ...

Joe Pilot didn't put the flaps there, Bob the designer did. He had a
"purpose", which was probably to lower the stall speed and thus the
approach speed and all the other good things that come from that.

[BobW]

On 8/16/2011 8:26 PM, toad wrote:
> On Aug 15, 10:55 pm, > wrote:
>>
>> The 'purpose of flaps' - Is this where philosophy enters the aerodynamic world
>> definable by flaps' effect on a glider's polar?
> ...
>> Where I'm headed with this is, one can reasonably conclude the 'purpose of
>> flaps' is whatever JGP decides, within their aerodynamic capabilities. ...
>
> Joe Pilot didn't put the flaps there, Bob the designer did. He had a
> "purpose", which was probably to lower the stall speed and thus the
> approach speed and all the other good things that come from that.

Indeed the designer(s) did put the flaps on certain ships, not Joe Glider
Pilot. And today it's difficult to come any closer to getting inside the mind
of the designer *most* responsible for turning one subset of U.S. glider
pilot's minds onto the benefit of large deflection landing flaps than can be
done from a link earlier referenced by Wayne Paul...

http://www.soaridaho.com/Schreder/Stories/Schreder_on_Flaps.htm

*My* point was intended for JGP inside the cockpit while landing. It indeed
may be helpful to be even further inside the designer's mind...but it's not
necessary in order for JGP to extract the most benefits from the flaps, so
long as he understands their aerodynamic capabilities, whether his
understanding is gained entirely empirically or has a theoretically based assist.

Regards,
Bob W.

[T8]

On Aug 16, 10:26*pm, toad > wrote:

> Joe Pilot didn't put the flaps there, Bob the designer did. *He had a
> "purpose", which was probably to lower the stall speed and thus the
> approach speed and all the other good things that come from that.

Perhaps. But this *is* a pilots' forum and we all know that -- from
the pilot's point of view -- the world revolves about him, end of
story. I mean if it wasn't for glider pilots, there wouldn't be much
point in having glider designers. Ergo, Bob put 'em there to be
useful to me, period :-).

-Evan Ludeman / T8

[Craig Funston[_2_]]

> Perhaps. But this *is* a pilots' forum and we all know that -- from
> the pilot's point of view -- the world revolves about him, end of
> story. I mean if it wasn't for glider pilots, there wouldn't be much
> point in having glider designers. Ergo, Bob put 'em there to be
> useful to me, period :-).
>
> -Evan Ludeman / T8

True enough, although Dick was speaking from a solution oriented
standpoint that ignored perception issues. Kind of like the engineer on
the golf course joke http://www.ahajokes.com/gol010.html

I've flown the ASW-20A quite a bit & absolutely loved the combination of
high deflection flaps and spoilers. I suspect I'd like a flaps only
solution too.

Craig
--
Using Opera's revolutionary email client: http://www.opera.com/mail/

[Jonathon May[_2_]]

At 18:15 17 August 2011, T8 wrote:
>On Aug 16, 10:26=A0pm, toad wrote:
>
>> Joe Pilot didn't put the flaps there, Bob the designer did. =A0He had a
>> "purpose", which was probably to lower the stall speed and thus the
>> approach speed and all the other good things that come from that.
>
>Perhaps. But this *is* a pilots' forum and we all know that -- from
>the pilot's point of view -- the world revolves about him, end of
>story. I mean if it wasn't for glider pilots, there wouldn't be much
>point in having glider designers. Ergo, Bob put 'em there to be
>useful to me, period :-).
>
>-Evan Ludeman / T8
>

The duo discus has always been a great glider but it was not easy to
land.The latest version XL has flaps connected to the air brakes,and it has
transformed it's approach control to the point it is just as easy to land
as a K21.When the total mass is750Kg you need to let the designer do the
designing,flaps down,nose down and control the rest with stick and brake
just like any basic trainer.It reduces the work load,therfore increases
safety.
Arn't modern gliders great !
ever looked at a Kesteral 2 flap levers 1 for cruise/thermal second for
landing plus parachute release and jettison (2 levers) and then there is
the brake.
Arn't modern gliders great.

[GC[_2_]]

On 18/08/2011 00:44, Eric Greenwell wrote:
>
> Not only do they look like it, they are, in fact, bent down a bit. I saw
> that on my ASW 20 C, and I see it on my ASH 26 E.

But that's not really due to the flaps. The clever Schleicher mixer
design raises the ailerons as the flaps move to landing. ASH-25s show
it best of all.

That's why longer span Schleicher gliders are significantly easier to
manoeuvre on final than some other contemporary designs.

GC

[Scott[_7_]]

Here is a video example of flaps...(on powered planes)

http://freedom4um.com/cgi-bin/readart.cgi?ArtNum=133255

Scott

[Eric Greenwell[_4_]]

On 8/17/2011 2:50 PM, GC wrote:
> On 18/08/2011 00:44, Eric Greenwell wrote:
>>
>> Not only do they look like it, they are, in fact, bent down a bit. I saw
>> that on my ASW 20 C, and I see it on my ASH 26 E.
>
> But that's not really due to the flaps. The clever Schleicher mixer
> design raises the ailerons as the flaps move to landing. ASH-25s show it
> best of all.

My inner engineer must quibble with this, though I agree it is a clever
mixer system. On my 26 E, it even puts a little washout (ailerons up
slightly) in the thermalling flap position to improve control at low
circling speeds.

For the landing, it's the difference in control surface deflection that
does it: the high lift coefficient flap section requires a very low
angle of attack to produce the proper lift, so low that the low lift
coefficient aileron section is producing negative lift.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)
- "Transponders in Sailplanes - Feb/2010" also ADS-B, PCAS, Flarm
http://tinyurl.com/yb3xywl
- "A Guide to Self-launching Sailplane Operation Mar/2004" Much of what
you need to know tinyurl.com/yfs7tnz

[Bruce Hoult]

On Aug 18, 7:39*am, Jonathon May > wrote:
> The duo discus has always been a great glider but it was not easy to
> land.The latest version XL has flaps connected to the air brakes,and it has
> transformed it's approach control to the point it is just as easy to land
> as a K21.When the total mass is750Kg you need to let the designer do the
> designing

I'm experienced in the Janus (original model: flying tail, belly hook
only) and in the DG1000 but I've only had one flight in a Duo.

The Guy In Back got a bit preoccupied in the circuit trying to get a
balky radio to work, so I set up a reasonably tight final the same as
I would for a half brake approach in the DG1000 or Janus (with landing
flap).

Oops!! Captain she's not coming down!! It seems that they put pretty
much the same wimpy brakes in the Duo as in the Janus, but without the
benefit of the flaps.

Full brake did end up bringing us down to the threshold (which turned
out to be unnecessary as I was then told to land long) but it did
require everything, not the half I'd planned for.

[GC[_2_]]

On 18/08/2011 08:40, Eric Greenwell wrote:
> On 8/17/2011 2:50 PM, GC wrote:
>> On 18/08/2011 00:44, Eric Greenwell wrote:
>>>
>>> Not only do they look like it, they are, in fact, bent down a bit. I saw
>>> that on my ASW 20 C, and I see it on my ASH 26 E.
>>
>> But that's not really due to the flaps. The clever Schleicher mixer
>> design raises the ailerons as the flaps move to landing. ASH-25s show it
>> best of all.
>
> My inner engineer must quibble with this, though I agree it is a clever
> mixer system. On my 26 E, it even puts a little washout (ailerons up
> slightly) in the thermalling flap position to improve control at low
> circling speeds.
>
> For the landing, it's the difference in control surface deflection that
> does it: the high lift coefficient flap section requires a very low
> angle of attack to produce the proper lift, so low that the low lift
> coefficient aileron section is producing negative lift.
>

My inner engineer will pay that. :)

GC