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?

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: ---

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
66

Bruce,

Your Kestrel seems to have a different setup from mine. I have a
Series 1 bird, so maybe Slingsby changed the layout with later models?
Tow release is under the left inner thigh, rudder pedal adjustment is
under the right inner thigh. Drogue deploy is on the left cockpit
sidewall above the air vent, just in front of the panel; drogue
jettison is in the centre pedestal of the panel to the right of the
landing flap handle (with the nose vent control pull-knob between
them).
For me, it's a quick movement of the hand from the spoiler lever
forward to the drogue deploy; the drogue jettison is a bit further
since I have to reach the panel just to the right of my stick.
My spoliers only add 1 kt of sink, so I have to judge my location and
height for when to put on full flap. I like the comment in my POH
(sorry, can't quote it just now) about the spoilers being ineffective.

To try and keep on point here, LS-6, LS-10, LS-3, PIK 20 D, Ventus C,
ASW-17 come to mind as having full span flaperons. The entire
trailing edge moves the same amount when moved as flap or aileron.
ASW-20, PIK 20B, Zuni, SGS 1-35, HP Series, 301 Libelle, Diamants,
Ventus A/B, Kestrel, etc do NOT have full span flaperons. They have
flaps and ailerons, and varying degrees of interconnection between the
two.

Only plane I know of that had a full span flap that was used at large
deflections (greater than 30 degrees) was the HP-17. Notice, it did
not have full span flaperons. It had spoilers for roll control. And
I understand the contestants had a great time watching Schreder take
off with it, as he went from tip to tip, side to side on the runway
until he finally got the plane into the air. This was likely due to
the fact that you could only reduce the lift a bit on the high wing
and add drag to it to try and pick up the down wing.

Full span, large deflection flaperons will likely provide very poor
roll control at any deflection beyond about 30-45 degrees, as the flap
will be likely be stalled, and the main thing you will get is
differential drag or a yawing moment when you moved the stick to try
and roll the plane. Oh, and I don't consider the Ventus A/B, Mini
Nimbus, or Mosquito to have drag flaps. They have cruise flaps and
trailing edge air brakes. Drag flaps have you looking out the top of
the canopy at where you are going to land when you put them full on.
You are still looking out the front of the canopy at where you are
going to land with trailing edge air brakes.

The ASW-20 was the first to get the ailerons back up as the flaps went
on down, getting the plane into what a previous poster said is called
"crow mode" in the model world. I think the biggest thing it does is
makes it so the ailerons won't stall once you are on the ground in two
point, tail low attitude. I don't think it was done for added drag or
improved in flight handling. You already get ENORMOUS geometric twist
when your inboard flap is down 50 degrees and your ailerons are still
down 8. However, these flapped ships like to have the ailerons up
when sitting two point on the ground in order to have aileron
authority, and Schleicher got this (among so many other things) right
by putting them back up so you can leave the flaps all the way down
after you land. That way, your left hand doesn't have to keep jumping
around in the cockpit grabbing different handles. Set the flaps, use
the dive brakes and land. No more needed hand changes.

Steve Leonard

Steve Leonard wrote:
To try and keep on point here, LS-6, LS-10, LS-3, PIK 20 D, Ventus C,
ASW-17 come to mind as having full span flaperons. The entire
trailing edge moves the same amount when moved as flap or aileron.
ASW-20, PIK 20B, Zuni, SGS 1-35, HP Series, 301 Libelle, Diamants,
Ventus A/B, Kestrel, etc do NOT have full span flaperons. They have
flaps and ailerons, and varying degrees of interconnection between the
two.

Only plane I know of that had a full span flap that was used at large
deflections (greater than 30 degrees) was the HP-17. Notice, it did
not have full span flaperons. It had spoilers for roll control. And
I understand the contestants had a great time watching Schreder take
off with it, as he went from tip to tip, side to side on the runway
until he finally got the plane into the air. This was likely due to
the fact that you could only reduce the lift a bit on the high wing
and add drag to it to try and pick up the down wing.

Full span, large deflection flaperons will likely provide very poor
roll control at any deflection beyond about 30-45 degrees, as the flap
will be likely be stalled, and the main thing you will get is
differential drag or a yawing moment when you moved the stick to try
and roll the plane. Oh, and I don't consider the Ventus A/B, Mini
Nimbus, or Mosquito to have drag flaps. They have cruise flaps and
trailing edge air brakes. Drag flaps have you looking out the top of
the canopy at where you are going to land when you put them full on.
You are still looking out the front of the canopy at where you are
going to land with trailing edge air brakes.

The ASW-20 was the first to get the ailerons back up as the flaps went
on down, getting the plane into what a previous poster said is called
"crow mode" in the model world. I think the biggest thing it does is
makes it so the ailerons won't stall once you are on the ground in two
point, tail low attitude. I don't think it was done for added drag or
improved in flight handling. You already get ENORMOUS geometric twist
when your inboard flap is down 50 degrees and your ailerons are still
down 8. However, these flapped ships like to have the ailerons up
when sitting two point on the ground in order to have aileron
authority, and Schleicher got this (among so many other things) right
by putting them back up so you can leave the flaps all the way down
after you land. That way, your left hand doesn't have to keep jumping
around in the cockpit grabbing different handles. Set the flaps, use
the dive brakes and land. No more needed hand changes.

Steve Leonard

And unfortunately Schleicher patented the mixer - so one of the more
effective safety innovations has not been widely used.

Relying on a manual process as per T59D is a busy solution and error
prone. So it looks like the industry went to more powerful airbrakes and
dump the flaps on the ground run.

Pity really.

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

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


I know I'm getting in late on this but the original LS-3 had one full-
span control surface per wing panel. It was fairly flexible (said
anyone who ever removed one from the wing for maintenance) and
apparently required a fair amount of lead to mass balance (IIRC, 40
lbs. was mentioned, probably split between left and right). The result
was that the wings were not only quite heavy (175 lbs.each) but the
balance was biased towards the trailing edge, making it more awkward
to handle during rigging. Maximum flap settings were -7 to +10
degrees, probably to prevent the one-piece surface from distorting or
even splitting/buckling at the trailing edge at higher wing
deflections. The wing itself was very stiff (probably another reason
for its weight since this was pre-carbon fibre) so the deflection in
turbulence was low (read: it was a rough ride on the ridge). It sounds
a little odd but the glider was a joy to fly and both climbed and ran
very well when new. Alas, LS-3s experienced shrinkage over the spar
caps over time, which hurt the cruise performance though they still
climbed well. Some owners (including me) sanded and/or added gel coat/
filler to restore the original profile and the glider was transformed,
making it equal to the ASW 20, Ventus, and LS-6 of its day. It's still
a great, wonderfully strong airplane with a lot of performance that
gives its owners a great deal (for one with a good finish).

Not to be confused with the LS-3a or LS-3 17, both of which had more
conventional flap/aileron control surfaces and lighter wing panels.

Chip Bearden
ASW 24 "JB"
USA

On Mar 19, 2:58*pm, Chip Bearden wrote:
I don't know of any sailplane design that uses full span single surface
flaperons.

I know I'm getting in late on this but the original LS-3 had one full-
span control surface per wing panel. It was fairly flexible (said
anyone who ever removed one from the wing for maintenance) and
apparently required a fair amount of lead to mass balance (IIRC, 40
lbs. was mentioned, probably split between left and right). The result
was that the wings were not only quite heavy (175 lbs.each) but the
balance was biased towards the trailing edge, making it more awkward
to handle during rigging. Maximum flap settings were -7 to +10
degrees, probably to prevent the one-piece surface from distorting or
even splitting/buckling at the trailing edge at higher wing
deflections. The wing itself was very stiff (probably another reason
for its weight since this was pre-carbon fibre) so the deflection in
turbulence was low (read: it was a rough ride on the ridge). It sounds
a little odd but the glider was a joy to fly and both climbed and ran
very well when new. Alas, LS-3s experienced shrinkage over the spar
caps over time, which hurt the cruise performance though they still
climbed well. Some owners (including me) sanded and/or added gel coat/
filler to restore the original profile and the glider was transformed,
making it equal to the ASW 20, Ventus, and LS-6 of its day. It's still
a great, wonderfully strong airplane with a lot of performance that
gives its owners a great deal (for one with a good finish).

Not to be confused with the LS-3a or LS-3 17, both of which had more
conventional flap/aileron control surfaces and lighter wing panels.

Chip Bearden
ASW 24 "JB"
USA

And due to the lead in the wings, the German speakers in this group
will understand why the "LS-Drei" was referred to as the LS-Blei"...


Ray Lovinggood
Carrboro, North Carolina, USA

I've heard the LS-Blei joke many times, and laughed ruefully.
Interestingly, however, while the wings ARE heavy (my entire ASW 24
wing weighs as much as the root end of my LS-3 wing!), they're
comparable to those of the ASW 20B, a much more highly thought of
glider with almost identical performance (when the LS-3 wings are
profiled properly, that is).

Pursuant to the original poster's question, I should have added that
the LS-3 has large, very effective conventional dive brakes and does
not rely on the flaps for glide path control. Also, while the ailerons
are light and very effective when the flaperons are set at 0 to 10+
degrees, the stick is very stiff with the flaperons at -7 degrees (at
least in my old glider). I didn't have much ridge time in my LS-3 but
I recall on more than one occasion yanking the flaps down when
encountering a strong rolling motion so that I could apply countering
aileron. This also had the effect of lifting me off the ridge at the
same time. It was a nice combination but I would have prefered just
being able to roll a little easier. Pilots with more ridge time might
disagree this was necessary but the ailerons were still very stiff. I
presume this was from the geometry of the mixer since much of it was
apparent even on the ground. I hope I'm not making the LS-3 out to be
unpleasant in any way. It was a great glider that I flew happily for
many years.

Chip Bearden
ASW 24 "JB"
USA