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Flaps/No flaps...practical difference??



 
 
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  #31  
Old August 16th 19, 11:07 PM posted to rec.aviation.soaring
BobW
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Posts: 460
Default Flaps/No flaps...practical difference??


Having flown a lot both ASW20 and D2, I would not try to land one glider
in a place I would not land the other as well.


Ditto - ASW20, Discus 2 and Ventus 2bx experience under my belt. I have
never felt there was a place I could land one of the flapped ships and not
the D2.

(although the "Jesus" flap setting of the earlier ASW 20s was
interesting!)


Captain Obvious here (maybe)...

There's a world of difference between 'mere' camber-changing flaps (with or
without a 'landing' position) and large-deflection landing-flaps in terms of
steepest-glide-angle at approach-speed, and reduced (compared to unflapped
ships of equal span) stall speed, everything else being equal (which of course
it ain't). The devil's in the details.

Yeah, likely the main benefit of stalling-speed-reduction occurs somewhere
around (say) 30-ish degrees of flap deflection, beyond which the remaining
aerodynamic effect is pretty much additional drag, and yeah, manufacturers of
'flapped ships (w/o large deflection capability)' almost certainly optimize
such designs (and their landing spoilers) so that the *primary* purpose of the
flaps is to maximize soaring-performance-range for some design-targeted span
(and not maximize short-field capability), and hence == when considering
*these* sorts of flapped designs == there's arguably little
landing-capability difference between flapped and unflapped ships.

But to suppose that's true for *all* flapped designs (i.e. those w.
large-deflection landing flaps, e.g. some early versions of ASW 20s, pre-D
versions of PIK-20s, and a few, semi-rare (even in the U.S.; likely even more
rare in EASA-land) U.S. designs (Nugget, SGS 1-35, Zuni, many older HPs,
etc.)), is incorrect. Depending on the ship, *seriously* incorrect.

Most U.S. pilots w. 1-26 experience would likely agree no other glider would
be their first choice for landing in a small/approach-obstructed field. I
would, too, but for the HP-14 I flew for several hundred hours, more or less
immediately after my 1-26 time. The Zuni in which I have most of my
flapped-ship time, not so much, though its actual touchdown speed is (thanks
to its flaps) lower than all other 15-meter span glass ships with which I have
observational experience since ~1980.

Reiterating...the devil is in the details in the case of 'flaps.' All flaps
aren't the same - not by a long stretch. I chose large-deflection
landing-flapped ships for all my single-seaters, post-1-26, exactly for this
reason...and continue to believe they're something of a 'lost religious war'
in soaring-land.

Point being, anyone seriously claiming 'there's no practical difference in
landing capability' between flapped and unflapped gliders is either genuinely
ignorant, or 'discussionally choosing' to ignore the very real additional
landing-capabilities associated with large-deflection landing-flaps.

YMMV,
Bob - Cap't. Obvious - W.

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  #32  
Old August 17th 19, 01:59 AM posted to rec.aviation.soaring
Dave Nadler
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Posts: 1,366
Default Flaps/No flaps...practical difference??

On Friday, August 16, 2019 at 6:07:44 PM UTC-4, BobW wrote:
Captain Obvious here (maybe)...

There's a world of difference between 'mere' camber-changing flaps (with or
without a 'landing' position) and large-deflection landing-flaps in terms of
steepest-glide-angle at approach-speed, and reduced (compared to unflapped
ships of equal span) stall speed, everything else being equal (which of course
it ain't). The devil's in the details.

Yeah, likely the main benefit of stalling-speed-reduction occurs somewhere
around (say) 30-ish degrees of flap deflection, beyond which the remaining
aerodynamic effect is pretty much additional drag, and yeah, manufacturers of
'flapped ships (w/o large deflection capability)' almost certainly optimize
such designs (and their landing spoilers) so that the *primary* purpose of the
flaps is to maximize soaring-performance-range for some design-targeted span
(and not maximize short-field capability), and hence == when considering
*these* sorts of flapped designs == there's arguably little
landing-capability difference between flapped and unflapped ships.

But to suppose that's true for *all* flapped designs (i.e. those w.
large-deflection landing flaps, e.g. some early versions of ASW 20s, pre-D
versions of PIK-20s, and a few, semi-rare (even in the U.S.; likely even more
rare in EASA-land) U.S. designs (Nugget, SGS 1-35, Zuni, many older HPs,
etc.)), is incorrect. Depending on the ship, *seriously* incorrect.

Most U.S. pilots w. 1-26 experience would likely agree no other glider would
be their first choice for landing in a small/approach-obstructed field. I
would, too, but for the HP-14 I flew for several hundred hours, more or less
immediately after my 1-26 time. The Zuni in which I have most of my
flapped-ship time, not so much, though its actual touchdown speed is (thanks
to its flaps) lower than all other 15-meter span glass ships with which I have
observational experience since ~1980.

Reiterating...the devil is in the details in the case of 'flaps.' All flaps
aren't the same - not by a long stretch. I chose large-deflection
landing-flapped ships for all my single-seaters, post-1-26, exactly for this
reason...and continue to believe they're something of a 'lost religious war'
in soaring-land.


I've got an RHJ-8 looking for a home, flaps not quite as effective as HP-14
but quite frightening to passengers unused to such a treat of a landing...

  #33  
Old August 17th 19, 02:18 PM posted to rec.aviation.soaring
BobW
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Posts: 460
Default Flaps/No flaps...practical difference??

On 8/16/2019 6:59 PM, Dave Nadler wrote:
On Friday, August 16, 2019 at 6:07:44 PM UTC-4, BobW wrote:
Captain Obvious here (maybe)...

There's a world of difference between 'mere' camber-changing flaps (with
or without a 'landing' position) and large-deflection landing-flaps in
terms of steepest-glide-angle at approach-speed, and reduced (compared to
unflapped ships of equal span) stall speed, everything else being equal
(which of course it ain't). The devil's in the details.

Snip...


Most U.S. pilots w. 1-26 experience would likely agree no other glider
would be their first choice for landing in a small/approach-obstructed
field. I would, too, but for the HP-14 I flew for several hundred hours,
more or less immediately after my 1-26 time...


Reiterating...the devil is in the details in the case of 'flaps.' All
flaps aren't the same - not by a long stretch. I chose large-deflection
landing-flapped ships for all my single-seaters, post-1-26, exactly for
this reason...and continue to believe they're something of a 'lost
religious war' in soaring-land.


I've got an RHJ-8 looking for a home, flaps not quite as effective as
HP-14 but quite frightening to passengers unused to such a treat of a
landing...


Oh man..born 40 years too soon, I was! I lusted after this ship (and its two
siblings) ever since I learned of 'em. May yours find a(nother) good home!

Bob W.

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  #34  
Old August 17th 19, 07:38 PM posted to rec.aviation.soaring
Charlie M. (UH & 002 owner/pilot)
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Posts: 1,225
Default Flaps/No flaps...practical difference??

Having landed a 1-26 in a place local hang glider pilots said was that unlandable (one HG pilot showed up at our field, having his kidlets learn, he mentioned, I stated as fact since I was the 1-26 pilot involved), yes a ASW-20a in "full dump it mode" (landing flap, full brakes) has a L/D of a homesick brick.....
Good planning allows a lot of glass ships into small places....what do you practice?
A 20-a can go into very small spots, a 20-c needs a bit more.
VERY sharp in a no -flapped ship......sorry, not the same....

General flying, nut behind the stick is likely 85% of the equation, forget flaps unless high speed or short off field.
  #35  
Old August 17th 19, 10:37 PM posted to rec.aviation.soaring
Al McNamara[_4_]
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Posts: 5
Default Flaps/No flaps...practical difference??

Trying to get back to your original question, while it is important to
remember that there are considerable differences between different gliders
(and generations of glider) some of the practical differences that you
might encounter include:

(1) Increased workload on the ground run (some flapped gliders need a
change from negative to positive flaps to prevent a wing dropping)

(2) Easier unstick once in a positive flap setting. Only really a factor
if launching from a short airfield or behind a low power tug.

(3) Lower thermaling speeds, particularly when heavy (so generally better
climb rates)

(4) Reduced roll control in positive flap settings, particularly in older
designs. This can be a factor when manoeuvring in a busy thermal and/or
lower down. In my experience not a major factor in more modern types

(4) Higher workload in flight (you need to consider what flap setting you
need)

(5) Steeper approach attitude, so better visibility and potential to land
shorter (very type specific)

(6) Increased workload on the landing run (some, particular older, flapped
gliders need a move to negative flap on the ground run to maintain roll
control

Some are positive, some negative, but if used properly, you will definitely
get a performance benefit on most cross country days, provided you get the
flap settings right. The price of the performance increase is a higher
workload. In my view, whether this trade off is worthwhile is sometimes as
much about you and your capacity/experience as the other factors.

  #36  
Old Yesterday, 09:30 AM posted to rec.aviation.soaring
krasw
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Posts: 487
Default Flaps/No flaps...practical difference??

On Saturday, 17 August 2019 01:07:44 UTC+3, BobW wrote:

Point being, anyone seriously claiming 'there's no practical difference in
landing capability' between flapped and unflapped gliders is either genuinely
ignorant, or 'discussionally choosing' to ignore the very real additional
landing-capabilities associated with large-deflection landing-flaps.

YMMV,
Bob - Cap't. Obvious - W.


Sure, if you totally botch landing circuit and approach way too high and fast, '20 flaps will get you down sooner than D2 airbrakes. But if you get into this situation, glider you need is ASK21 with flight instructor.
  #37  
Old Yesterday, 03:30 PM posted to rec.aviation.soaring
BobW
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Posts: 460
Default Flaps/No flaps...practical difference??

On 8/18/2019 2:30 AM, krasw wrote:
On Saturday, 17 August 2019 01:07:44 UTC+3, BobW wrote:

Point being, anyone seriously claiming 'there's no practical difference
in landing capability' between flapped and unflapped gliders is either
genuinely ignorant, or 'discussionally choosing' to ignore the very real
additional landing-capabilities associated with large-deflection
landing-flaps.

YMMV, Bob - Cap't. Obvious - W.


Sure, if you totally botch landing circuit and approach way too high and
fast, '20 flaps will get you down sooner than D2 airbrakes. But if you get
into this situation, glider you need is ASK21 with flight instructor.


Continuing (I think) a slow drift from the original poster's question...

I guess I don't understand the point you seem to me to be supporting. When I
imagine the "50%-extended glidepath" height-vs.horizontal distance diagram, at
normal approach speed, of (say) an ASW-20 (w. 65-degree flap capability) and a
D2, it strongly suggests to me that the former ship will have a greater number
of theoretically available fields from which to safely choose, independent of
anything else...pilot skill, trees, wind shears, etc. It will also be capable
of actually touching down with less energy to dissipate.

I'm not bashing flapless gliders; simply trying to make the point that
gliders' *usable* landing capabilities, differ...with real-world practical
effects. I'm OK with agreeing to disagree.

Anecdotally speaking, my habit/landing-preference with large-deflection
landing-flap-equipped gliders is to fly landing patterns where the terminal
portion of the approach employs full flap deflection, because: it's fun, not
fundamentally difficult, *and* it's useful prep for outlanding in
approach-obstructed/short fields, and in that sense no different than choosing
to consistently fly/practice full-spoiler-opening approaches in spoiler-only
ships. To each their own...

YMMV.

Bob W.

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  #38  
Old Yesterday, 05:02 PM posted to rec.aviation.soaring
Charlie M. (UH & 002 owner/pilot)
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Posts: 1,225
Default Flaps/No flaps...practical difference??

Sorta my point on a -20A.....get current in the spring, then do a local pattern "way high" full flaps, full dive brakes, roll the nose over....sheesh....
I have shoveled into small fields from a 1-26 and up.....sorta hard to beat a -20A in a very small field.
Yes, I have -24 and -28 off airport landings.
Circuit may not be the issue, crappy fields (yes, you didn't call it quits soon enough...) may NEED max decent rate.
Sorry, standard class would have a hard time compared to many flapped ships.
YMMV...

BTW, I "believe" while testing the -20A, pilot was on final at 1000' above landing spot....Hang everything out, roll nose beyond vertical, land on spot......no turns..,,didn't exceed any speed......try that in a non flapped ship.
No, I don't believe the -20B or C could do that.
I did once a year for practice since it may loosen bottom wing/flap seals.....so....a test....
  #39  
Old Today, 07:13 AM posted to rec.aviation.soaring
Bob Youngblood
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Posts: 78
Default Flaps/No flaps...practical difference??

On Sunday, August 18, 2019 at 12:02:57 PM UTC-4, Charlie M. (UH & 002 owner/pilot) wrote:
Sorta my point on a -20A.....get current in the spring, then do a local pattern "way high" full flaps, full dive brakes, roll the nose over....sheesh....
I have shoveled into small fields from a 1-26 and up.....sorta hard to beat a -20A in a very small field.
Yes, I have -24 and -28 off airport landings.
Circuit may not be the issue, crappy fields (yes, you didn't call it quits soon enough...) may NEED max decent rate.
Sorry, standard class would have a hard time compared to many flapped ships.
YMMV...

BTW, I "believe" while testing the -20A, pilot was on final at 1000' above landing spot....Hang everything out, roll nose beyond vertical, land on spot......no turns..,,didn't exceed any speed......try that in a non flapped ship.
No, I don't believe the -20B or C could do that.
I did once a year for practice since it may loosen bottom wing/flap seals......so....a test....


I owned a 20L model that had that same flap configuration. There was never any doubt about putting that thing down in some very difficult places. Alfonso, E9, and I would see just how short we could land. The bird was the best flying ship that I have ever owned. I wish my 27B had that same configuration.
 




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