Flaps VS Airbrakes/Spoilers

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/St...r_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.

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

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/

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.

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.

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)

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

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

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/St..._HP_flight.htm
http://www.soaridaho.com/Schreder/St...r_on_Flaps.htm
http://www.soaridaho.com/Schreder/HP...st_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

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