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Flaps VS Airbrakes/Spoilers



 
 
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  #11  
Old August 16th 11, 11:10 PM
Walt Connelly Walt Connelly is offline
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Posts: 365
Default

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
  #12  
Old August 17th 11, 03:26 AM posted to rec.aviation.soaring
toad
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Posts: 229
Default Flaps VS Airbrakes/Spoilers

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.
  #13  
Old August 17th 11, 01:47 PM posted to rec.aviation.soaring
[email protected]
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Posts: 2,124
Default Flaps VS Airbrakes/Spoilers

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)
  #15  
Old August 17th 11, 04:34 PM posted to rec.aviation.soaring
toad
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Posts: 229
Default Flaps VS Airbrakes/Spoilers

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
  #16  
Old August 17th 11, 05:32 PM posted to rec.aviation.soaring
Wayne Paul
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Posts: 905
Default Flaps VS Airbrakes/Spoilers

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.

  #17  
Old August 17th 11, 06:28 PM posted to rec.aviation.soaring
BobW
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Posts: 504
Default 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.
  #18  
Old August 17th 11, 07:15 PM posted to rec.aviation.soaring
T8
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Posts: 429
Default Flaps VS Airbrakes/Spoilers

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
  #19  
Old August 17th 11, 08:09 PM posted to rec.aviation.soaring
Craig Funston[_2_]
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Posts: 115
Default Flaps VS Airbrakes/Spoilers


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/
  #20  
Old August 17th 11, 08:39 PM posted to rec.aviation.soaring
Jonathon May[_2_]
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Posts: 88
Default Flaps VS Airbrakes/Spoilers

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.


 




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