Full-span flaperons as airbrakes?

Hi, do any gliders have full-span flaperons that also act as airbrakes
(say at 70-90 degree), or do you lose all aileron authority when the
flaperons are that deflected?

Bert,

All the sailplanes, I am aware of, that use flaps for glide-slope control also have ailerons. (PIK-20B, 1-35, Concept 20, the entire Schreder series, etc.) None of the mentioned models' wing control surfaces are full-span flaperons.

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


"Bret" wrote in message ...
Hi, do any gliders have full-span flaperons that also act as airbrakes
(say at 70-90 degree), or do you lose all aileron authority when the
flaperons are that deflected?

On Mar 6, 8:12*pm, Bret wrote:
Hi, do any gliders have full-span flaperons that also act as airbrakes
(say at 70-90 degree), or do you lose all aileron authority when the
flaperons are that deflected?

Kestrel 19 has full span flaperons. The inboard section, in climb and
cruise settings, deflects half the range of the outboard sections. A
second, panel mounted, landing flap handle, allows half or full
landing flap deflections of the inboard sections, to a maximum of 35
degrees. This generates high drag and lift for glide path control
when landing. Half landing flap may be used when ground launching and
will add 200ft or more to the launch height. Derek Piggott has
described it as a rather complex cockpit as gliders go, as there are
also air brakes and a tail chute.

Frank Whiteley

On Mar 6, 10:12*pm, Bret wrote:
Hi, do any gliders have full-span flaperons that also act as airbrakes
(say at 70-90 degree), or do you lose all aileron authority when the
flaperons are that deflected?

I agree with Wayne's reply.

I can understand the simplicity: No spoilers/air-brakes to build into
the wing. No internal linkage to build into the wing (just control
the flaperons at the root). But I think your concern about roll
control is valid. I once built an R/C model with the setup you
describe. Landing was very tricky, too tricky, especially with any
crosswind.

Regards,

-Doug

On Sat, 06 Mar 2010 19:12:52 -0800, Bret wrote:

Hi, do any gliders have full-span flaperons that also act as airbrakes
(say at 70-90 degree), or do you lose all aileron authority when the
flaperons are that deflected?

Yes. Of course - there's total flow separation on the back of flaps in
landing position, so ailerons would have very little effect if they
matched the flap position.

Take a look at an ASW-20. During normal flight (flaps between -9 and +8
degrees) the flaps and ailerons neutral points move together (in roll
flaps move half the deflection of the ailerons). In landing flap (around
+40 degrees) the ailerons move to -8 degrees to maintain good roll
authority. This is known in RC circles as Crow Mode and the aerodynamic
wing twist induces is a very effective drag generator.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

"Martin Gregorie" wrote in message ...
On Sat, 06 Mar 2010 19:12:52 -0800, Bret wrote:

Hi, do any gliders have full-span flaperons that also act as airbrakes
(say at 70-90 degree), or do you lose all aileron authority when the
flaperons are that deflected?

Yes. Of course - there's total flow separation on the back of flaps in
landing position, so ailerons would have very little effect if they
matched the flap position.

Take a look at an ASW-20. During normal flight (flaps between -9 and +8
degrees) the flaps and ailerons neutral points move together (in roll
flaps move half the deflection of the ailerons). In landing flap (around
+40 degrees) the ailerons move to -8 degrees to maintain good roll
authority. This is known in RC circles as Crow Mode and the aerodynamic
wing twist induces is a very effective drag generator.


The HP-18 has a system similar to the ASW-20. Many HP-16 and RS-15 builders have also incorporated the flaps/aileron interlink mechanism.

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

Or consider the ASW-12. No spoilers/airbrakes and the flaps did not
move much (i.e. flaps were little or no help for glide path control).
Later versions had a tail chute. Now *there's* a real man's glider!
Kudos to anyone who dared to fly it.

Regards,

-Doug

Wayne Paul wrote:
Bert,

All the sailplanes, I am aware of, that use flaps for glide-slope control also have ailerons. (PIK-20B, 1-35, Concept 20, the entire Schreder series, etc.) None of the mentioned models' wing control surfaces are full-span flaperons.

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


"Bret" wrote in message ...
Hi, do any gliders have full-span flaperons that also act as airbrakes
(say at 70-90 degree), or do you lose all aileron authority when the
flaperons are that deflected?


Kestrel 19m (Slingsby T59D) has full span flaperons with the same mixer
capability of the ASW20 - the correct procedure is to put the flaps into
negative territory, then apply the landing flap lever. That way you have
wonderful roll authority, ailerons slightly drooped and ~35 degrees of
landing flap.

Flaps and ailerons are separate - The mixer applies proportional flap
deflection to the ailerons - so - If you do it wrong the ailerons go to
almost full down deflection and you only (effectively) have upward
movement on one to cause roll. Makes turns onto finals interesting with
those long heavy wings.

I don't know of any sailplane design that uses full span single surface
flaperons.

--- news://freenews.netfront.net/ - complaints: ---

Frank Whiteley wrote:
On Mar 6, 8:12 pm, Bret wrote:
Hi, do any gliders have full-span flaperons that also act as airbrakes
(say at 70-90 degree), or do you lose all aileron authority when the
flaperons are that deflected?

Kestrel 19 has full span flaperons. The inboard section, in climb and
cruise settings, deflects half the range of the outboard sections. A
second, panel mounted, landing flap handle, allows half or full
landing flap deflections of the inboard sections, to a maximum of 35
degrees. This generates high drag and lift for glide path control
when landing. Half landing flap may be used when ground launching and
will add 200ft or more to the launch height. Derek Piggott has
described it as a rather complex cockpit as gliders go, as there are
also air brakes and a tail chute.

Frank Whiteley
Rather complex? Surely not.

You establish a nice steady final approach using thermal flap so you can
see the runway over the very high instrument panel.
Then you use your left hand to select 55-70kt flap (-2) - flaps forward
Then you reverse direction with the same hand and pull the separate
landing flap lever backwards to half or full flap. Best be sure you can
make the field before you do this as dumping the landing flap will
result in a lot of lost height and full landing flap steepens the
approach appreciably.
Simultaneously you use your other left hand to control the finer
approach sink rate with the modest airbrakes.
Maybe there is reason in this - you effectively have to allow the
airbrakes to retract as you apply landing flap.

While doing this you maintain roll and pitch control with your right and
on the stick, and adjust the trim using the trigger on the base of the
stick with your little finger.
Did I mention that you had best have not neglected to lock the
undercarriage down with your right hand on downwind. If not you use your
other right hand to do it now.
In the event that you are too high - or approaching a very short field
over obstacles you may want to deploy the parachute.
Now there are three identical feeling little handles down there between
the stick and the panel. Remember the left most will operate the cable
release, no use to you here. The left of centre one will release the
parachute in case you no longer want it and the little fairing for the
rudder... And the one you want is on the right hand side under your
thigh (inevitably) So you can use your other right hand to dig it out
and yank HARD. Then nothing happens till you wiggle the rudder, at which
point it is best to have already lowered the nose to counter the
surreptitious slow down. At this point - if you can see it over your
toes it is out of glide range.

Then you might want to pull the left hand (but not cable release) handle
to jettison the parachute as you cross the fence - in case the parachute
hooks on something well anchored (like a fence). In his instance it is
useful to have another left hand available as the airbrakes will tend to
close without something to hold them open, and the fence at the other
end of the field may be looming.

In practice it all works quite well, the Kestrel is very stable and
tolerates the hand swapping and general fidgeting - but it is a cockpit
you need to know before you try to fly it. There are lots of separate
controls in close proximity - and the correct combinations are important
lest the beastie rise up and bite you.

--- news://freenews.netfront.net/ - complaints: ---

On Mar 7, 12:17*pm, Bruce wrote:

I don't know of any sailplane design that uses full span single surface
flaperons.

LS6 & 10 have full span flaperons. Actually, built in two pieces and
hinged separately (due to a kink in the trailing edge), but linked
together and driven by one pushrod per side.

No fancy mixer, landing flaps puts the entire training edge down about
15 degrees which adds a useful about of drag while keeping good
aileron control.
But the 6's landing flap in no way compares to the ASW-20, Ventus B,
HP, PIK, etc. Those are FLAPS!

Kirk
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