Landing Flap Video

[BobW]

Check out...

http://www.youtube.com/watch?v=PXwy7dsLndM

....for a nice/useful/short video of two flapped landings in an HP-14,
owned/flown/filmed by Wayne Paul (and posted here with his permission).
Curious reader-pilots may find the following information helpful, should they
attempt to extract directly-/potentially-useful-to-them-information from the
video:
- "The tow pilot confirms my estimate that the winds were less than five knots."
- The distance from the beginning of asphalt to the start of the first stripe
is 120 feet.
- The stripe length is 120 feet.
- The stripe spacing is 80 feet. (Hence the distance from the start of one
stripe to the start of the next is 200 feet.)
- I have no idea where the roundout-aiming-point was for either landing.

For curious readers perhaps not terribly familiar with the traits/benefits of
large-deflection landing flaps, this video nicely illustrates some 'you can
bank on it' aspects of 'em.

1) When I estimate both landings' touchdown points and further estimate the
landing rolls, I come up with ~300 feet in both cases. The reason the landing
roll doesn't decrease from the 60-degree-flapped touchdown to the
90-degree-flapped touchdown, is because (for all practical purposes) flaps
stop adding lift after about 30-45 degrees of deflection; beyond that they add
only drag. But the short rollout distance nicely illustrates the
speed-reducing benefits of flaps.

2) Though it's impossible to tell from the video at what point the
60-/90-degrees of flap are deployed, one *can* get a sense for the drag
increment of those last 30-degrees by contrasting the approach angles on short
final, prior to roundout initiation. Steep approach without speed
increase...very nice; also very stable, wonderful visibility, simple to judge
one's roundout point, and great fun!

HP-14's land at ~5.5psf wing loading. It's an accurate statement that - when
Joe Pilot is using full flaps - they can easily/safely be put into fields
unavailable to 1-26 drivers, simply because they can approach more steeply
over field-bordering obstacles. As for the rollout, how many 1-26 drivers
routinely roll no more than 300 feet on a hard surface after touchdown? (And
how long does your skid plate last?)

IMHO, large deflection landing flaps on gliders are the best kept sailplane
secret in the last half century.

Enjoy!
Bob W.

[Scott[_7_]]

On 8-2-2011 02:15, BobW wrote:

>
> IMHO, large deflection landing flaps on gliders are the best kept
> sailplane secret in the last half century.
>
> Enjoy!
> Bob W.

As a noob to gliders (coming from powered airplanes), I always thought
that spoilers were "the bomb" :) One thing I like about spoilers over
flaps is that you can go from full spoilers to no spoilers instantly
without bad effects. Can't do that with flaps...if you misjudge and put
on too much, too early, there isn't much you can do except
undershoot...but maybe you can dump some flaps since gliders tend to
have more wing to work with than their powered brothers. But it does
make sense that you can probably land shorter with these type of flaps
over just spoilers. Now I'll have to go watch the video :)

[Willy VINKEN]

Lots have been said about flaps-reducing while on final.
I know at least of one other ASH25 pilot who has done it
gently without harmful effects (on final).
Last week, I've tried it in calm evening air at 1500 feet,
checking 2 independent digital altimeters.
A gentle reduction from from 'L' position to neutral made us
loose about 10 feet (natural ~5 second descent included).
A brutal 'L' to 'N' caused a 25-30 feet loss.
Some sailplanes are probably less forgiving.
I'd be glad to hear about pilots who have tried it for real.
wv


On Tue, 02 Aug 2011 10:35:37 +0000, Scott >
wrote:

>On 8-2-2011 02:15, BobW wrote:
>
>>
>> IMHO, large deflection landing flaps on gliders are the best kept
>> sailplane secret in the last half century.
>>
>> Enjoy!
>> Bob W.
>
>As a noob to gliders (coming from powered airplanes), I always thought
>that spoilers were "the bomb" :) One thing I like about spoilers over
>flaps is that you can go from full spoilers to no spoilers instantly
>without bad effects. Can't do that with flaps...if you misjudge and put
>on too much, too early, there isn't much you can do except
>undershoot...but maybe you can dump some flaps since gliders tend to
>have more wing to work with than their powered brothers. But it does
>make sense that you can probably land shorter with these type of flaps
>over just spoilers. Now I'll have to go watch the video :)
>

[Berry[_2_]]

In article >, BobW >
wrote:

> Check out...
>
> http://www.youtube.com/watch?v=PXwy7dsLndM
>
> ...for a nice/useful/short video of two flapped landings in an HP-14,
> owned/flown/filmed by Wayne Paul (and posted here with his permission).
> Curious reader-pilots may find the following information helpful, should they
>

Nice. Enjoyed the videos.


Had the distinct privilege of flying an HP-16 once (Thanks Dr. Jim). It
has the infamous "flaps and V-tail of death" that I had always heard
spell certain doom. In spite of the hype from know-it-alls who had never
actually flown with flaps or V-tails, I found the handling of the V-tail
was indistinguishable from that of a cruciform or T tail glider and the
flaps were just tremendous fun. In the pattern, I turned final at 600
feet and when the numbers disappeared under the nose I started rolling
in flaps. I kept on rolling in flaps until the numbers appeared again.
The horizon was way up the canopy at this point. Glanced at the airspeed
and it read 60 mph, so I rolled in a little more flap. I don't think I
ever actually reached the full 90 degree deflection. When the ground got
close enough that I could not stand it, I counted to three (quickly) and
flared. Touched down just past my aim point, slightly tail low, and
made a very short rollout. Not much different from landing an older
Cessna with big flaps and power off.

I think flaps for glidepath control on gliders got a bad rap because
some models of the Schweizer 1-35 had inadequate flap and were flown by
those who were not careful to control their speed on final.

[Wayne Paul]

Dr Jim's HP-16 is beautiful!!
http://www.soaridaho.com/Schreder/HP-16/N8DC/N8DC_First_Flight.htm

Wayne
HP-14 "6F"

"Berry" wrote in message
...

In article >, BobW >
wrote:

> Check out...
>
> http://www.youtube.com/watch?v=PXwy7dsLndM
>
> ...for a nice/useful/short video of two flapped landings in an HP-14,
> owned/flown/filmed by Wayne Paul (and posted here with his permission).
> Curious reader-pilots may find the following information helpful, should
> they
>

Nice. Enjoyed the videos.


Had the distinct privilege of flying an HP-16 once (Thanks Dr. Jim). It
has the infamous "flaps and V-tail of death" that I had always heard
spell certain doom. In spite of the hype from know-it-alls who had never
actually flown with flaps or V-tails, I found the handling of the V-tail
was indistinguishable from that of a cruciform or T tail glider and the
flaps were just tremendous fun. In the pattern, I turned final at 600
feet and when the numbers disappeared under the nose I started rolling
in flaps. I kept on rolling in flaps until the numbers appeared again.
The horizon was way up the canopy at this point. Glanced at the airspeed
and it read 60 mph, so I rolled in a little more flap. I don't think I
ever actually reached the full 90 degree deflection. When the ground got
close enough that I could not stand it, I counted to three (quickly) and
flared. Touched down just past my aim point, slightly tail low, and
made a very short rollout. Not much different from landing an older
Cessna with big flaps and power off.

I think flaps for glidepath control on gliders got a bad rap because
some models of the Schweizer 1-35 had inadequate flap and were flown by
those who were not careful to control their speed on final.

[BobW]

On 8/2/2011 4:35 AM, Scott wrote:
> On 8-2-2011 02:15, BobW wrote:
>
>>
>> IMHO, large deflection landing flaps on gliders are the best kept
>> sailplane secret in the last half century.
>>
>> Enjoy!
>> Bob W.
>
> As a noob to gliders (coming from powered airplanes), I always thought that
> spoilers were "the bomb" :) One thing I like about spoilers over flaps is that
> you can go from full spoilers to no spoilers instantly without bad effects.

A comforting - if not terribly accurate (see next para.) - theoretical thought
indeed. :) However, in the real world, there are precious few times when Joe
Clued-in Glider Pilot would actually want to or *need* to go from full
spoilers/flaps to none... assuming any halfway-decent landing pattern that
didn't also involve some sort of arcane practice.

> Can't do that with flaps...if you misjudge and put on too much, too early,
> there isn't much you can do except undershoot...but maybe you can dump some
> flaps since gliders tend to have more wing to work with than their powered
> brothers.

At the risk of starting a religious war, Joe Glider Pilot indeed *can* go
from full flap to zero flap w/o any ill/negatively-dramatic issues in gliders
(BTDT many times, just 'playing around')...with one
theoretical/possibly-real-world exception. The exception, of course, is
getting low and slow on a short final approach with gobs of flap hanging down,
in which case you *are* going to land short, the only question being whether
you do it at a higher speed (i.e. after you've retracted the flaps), or a
slower/lower-energy speed (i.e. playing the hand you've dealt yourself and
hoping for the best while contacting the ground as slowly as
theoretically/practically as is possible for whatever amount of 'too much'
flap you've hanging down). That noted, this exception is meaningful ONLY if
Joe Not-so-clued-in Glider Pilot gets a final approach horribly wrong and
waits until he's completely out of options to do something about it. (Extra
Credit Test Questions: Are you more likely to wind up on a low approach in a
glider with effective drag devices, or one with ineffective ones? Why?

Sure, it's fun - and quite possibly a useful learning exercise - to 'mentally
play with' these sorts of scenarios, but the fact of the matter is Joe Glider
Pilot should *never* 'suddenly' and 'shockingly' find himself hung out to dry
on any normal approach. In fact, I'd argue the only time the possibility of
being 'hung out to dry' should ever even rear its 'might-could-happen' head
are those times when JXCGP has reason to utilize his/the plane's fullest
capabilities shoehorning into a short/obstructed field (which skills of course
shoulda/woulda been safely practiced/determined beforehand)...and even then
the 'need' to do so should've been the result of an active *series* of choices
(maybe not all of them good! :)).

Not picking on you...just hypothesizing about possible future realities in any
XC glider pilot's future! As for 'horribly screwing up' a routine approach at
JGP's home field...should never happen, just as a departure from controlled
flight (i.e. the dreaded stall/spin turning base to final) should never
happen. Why would any of us want to go to these places? Yeah, the newer JGP
is, the more likely he is to be making massively large drag device settings
changes in any normal approach (kinda like a new bicycle rider's
easily-detectable large changes to maintain balance, contrasted with an
experienced rider's multitude of 'invisible' corrections), but there's no
'routinely defensible' reason for him to be *aiming* at the absolute near end
of the runway, even when practicing short field approaches.

But it does make sense that you can probably land shorter with these
> type of flaps over just spoilers. Now I'll have to go watch the video :)

Good on you...and may your flying experiences always occur on a happily
expanding palette!


Regards,
Bob W.

[BobW]

On 8/2/2011 8:25 AM, Willy VINKEN wrote:
>
>
> Lots have been said about flaps-reducing while on final.
> I know at least of one other ASH25 pilot who has done it
> gently without harmful effects (on final).
> Last week, I've tried it in calm evening air at 1500 feet,
> checking 2 independent digital altimeters.
> A gentle reduction from from 'L' position to neutral made us
> loose about 10 feet (natural ~5 second descent included).
> A brutal 'L' to 'N' caused a 25-30 feet loss.
> Some sailplanes are probably less forgiving.
> I'd be glad to hear about pilots who have tried it for real.
> wv

I have no ASH 25 experience, but many times (in an HP-14 and a Zuni [think
American design 'PIK-20']) I've gone from full flaps to zero flaps, by way of
learning 'useful bits' about plane/self. All initial experiments, of course,
well distant from the earth...

My HP had hydraulic flaps, which I considered a 'one-shot' in the landing
pattern, due to the 'somewhat funky' valve controlling the hydraulic system
(resetting it in flight was a contortionist's act). Best guess is it lost
perhaps 50 feet when you dumped the flaps, which blew to zero
'instantaneously' at 45 knots indicated. In any event, it distinctly 'settled'
if the stick position was maintained. Simultaneously pulling aft on the stick
when dumping its flaps at 'normal approach speeds' (attempting to maintain the
previous IAS) *seemed* as if it might reduce altitude lost, but that wasn't an
experiment I would've voluntarily tried 'on short final' to verify my surmise!
That said, the HP is the only glider in which I've ever done a 'go-around'.
Youthful stupidity combined with 'contest get-home-itis' brought me and a
nasty T-storm cell overhead the field simultaneously. I wound up dumping full
flaps no more than 300' agl on what I'd intended to be short final but which
transformed to an imminent overshoot due to a positive climb rate with full
flaps (!); the rain obscuring the view directly ahead combined with landing
crosswind on featureless prairie and the sheer (never seen before/since)
unlikely possibility of NOT descending w. full flaps in that ship, combined to
delay my detection of the worsening situation. The hardest part of 'getting
away with it' was resetting the flap valve, which I did on my second downwind
after successfully pulling off the instantaneous-flap-dump/180-degree turn.
(Yes, I re-ran the entire scenario in my mind lots!)

My (flap control mechanisms vary) Zuni's flaps are controlled by a handle
which moves through an arc of ~45-degrees from zero-to-full (~75-degrees), so
flaps can be pulled on/removed as rapidly as one can move arm/handle. It's
essentially pretty simple in the Zuni to dump the flaps while maintaining IAS
within a knot or so as the ship settles. Because the Zuni's flaps are
considerably weaker than were the HP-14's (as in, distinctly less effective
than those of the PIK-20A/Bs I've seen), its 50%/full-flap approach angles are
distinctly shallower than were the HP's. One not-so-great (IMHO) consequence
is, Joe Pilot is more likely to *have to* remove large amounts of flap on
short final in the Zuni if one encounters (say) heavy sink along the way.
BTDT, and removing flaps was never an issue.

In both ships I always simply attempted to fly speed stabilized approaches
regardless of flap position, which - in my experience - is not particularly
difficult. American pilots who've flown (say) Schweizer 1-34s or 2-32s can
easily relate, since with their speed-limiting dive brakes, Joe Pilot has to
effect pitch changes to maintain a constant speed as one modulates their
(very) effective spoilers.

HTH.

Regards,
Bob W.

[Bob Gibbons[_2_]]

On Tue, 02 Aug 2011 10:35:37 +0000, Scott >
wrote:

>On 8-2-2011 02:15, BobW wrote:
>
>>
>> IMHO, large deflection landing flaps on gliders are the best kept
>> sailplane secret in the last half century.
>>
>> Enjoy!
>> Bob W.
>
>As a noob to gliders (coming from powered airplanes), I always thought
>that spoilers were "the bomb" :) One thing I like about spoilers over
>flaps is that you can go from full spoilers to no spoilers instantly
>without bad effects. Can't do that with flaps...if you misjudge and put
>on too much, too early, there isn't much you can do except
>undershoot...but maybe you can dump some flaps since gliders tend to
>have more wing to work with than their powered brothers. But it does
>make sense that you can probably land shorter with these type of flaps
>over just spoilers. Now I'll have to go watch the video :)
>

This is a common misperception among power pilots concerning flaps on
sailplanes.

So long as you keep your approach speeds with a sufficient margin over
your flaps-up stalling speed, you can modulate the flaps as much as
you wish.

....Based in 18 years and 2000+ hrs in a PIK-20B with 90deg flaps.

Currently flying a Ventus C with standard spoilers but still miss the
impressive nose-down approach attitude of a full-flap landing.

Bob

[Bruce Hoult]

On Aug 2, 2:15*pm, BobW > wrote:
> As for the rollout, how many 1-26 drivers
> routinely roll no more than 300 feet on a hard surface after touchdown? (And
> how long does your skid plate last?)

I haven't flown one of those in anger, but most of my genuine landouts
have been in a PW5.

I always pace out the distances afterwards. The usual figures are
about 30 paces from a standard cattle farm fence to the main wheel
touchdown point, and another 30 paces to the point where I'm stopped.

If I call the paces 1m each then that's 200 feet -- from the fence,
not from touchdown.

Most of the rest of my landouts were in a Club Libelle. I'd say the
distances were quite similar. It, of course, has speed limiting
trailing edge airbrakes, which also have enough flap effect to lower
the stall by ~5 knots.


> IMHO, large deflection landing flaps on gliders are the best kept sailplane
> secret in the last half century.

I'd love to have some! But the trailing edge brakes as on the Club
Libelle, Hornet, Mosquito and I think also the Mini Nimbus and early
Ventus seem to give most of the same benefits, plus some extra ones.

[Bruce Hoult]

On Aug 2, 10:35*pm, Scott > wrote:
> As a noob to gliders (coming from powered airplanes), I always thought
> that spoilers were "the bomb" *:) *One thing I like about spoilers over
> flaps is that you can go from full spoilers to no spoilers instantly
> without bad effects. *Can't do that with flaps...if you misjudge and put
> on too much, too early, there isn't much you can do except
> undershoot...

You can if you resist the temptation to fly slower than a safe no-flap
speed until you are very close to the ground and/or have the runway
"made". Use the flaps to approach steeper, not to approach slower.

When I was flying a Janus (which has something like a 20º landing flap
position I think), I sometimes practiced going smoothly but reasonably
quickly between no flap and landing flap without feeling a change in G
forces. This involved applying forward elevator at the same time as
increasing the flap setting, and backward elevator at the same time as
reducing the flap setting.

If you do this then you can safely remove flap on approach without any
"sagging", provided that you keep the speed above 50 knots or so. Some
people liked to float the Janus in with landing flap at under 45 knots
on dead calm days, and that's usually going to be ok, but I always
added another 5 knots for my wife and kids. You can get rid of it
quickly enough once you're below a height you don't mind falling from.

[Bert TW]

I have been flying a Calif (90 deg flaps + spoilers) for many years,
and I didn't had any problem going from 90 deg to 8 deg on very short
final (and the flaps actually go 90 to -12 to +8 durig this procedure)
something like 15m above ground. Doing so took 1-2 sec typically.
Although the Calif flaps are the most powerful I've ever seen (flaps
and spoiler amount to 15 sft perpendicular to the slipstream...), they
have the backdraw that youi change lift, drag and attitude at the same
time, which needs some training.
Today I fly a Ventus C with standard SH airbrakes, and I never had the
feeling that I should want more powerful airbrakes.

Btw, the distance of the ground run after touchdown has little to do
with flaps & airbrakes - it's a function of the spped at touch down,
and your gross weight.

Bert TW

[Bob Kuykendall]

On Aug 2, 3:35*am, Scott > wrote:

> As a noob to gliders (coming from powered airplanes), I always thought
> that spoilers were "the bomb" *:) *One thing I like about spoilers over
> flaps is that you can go from full spoilers to no spoilers instantly
> without bad effects. *Can't do that with flaps...

You can't? That's odd, I've gone from flaps 90 to flaps minus 10, and
then back again on the approach. Many times. So this must be one of
those things that works in practice but not in theory.

Flaps decrease the stall speed. Airbrakes increase it. Flaps can also
be used to reflex the wing for more performance at high speed.
Airbrakes are a collection of hundreds of parts that you might use for
thirty seconds every flight. Flaps require seams back at the 83% chord
where the laminar flow has probably already tripped. Airbrakes
requires seams up at the 50% chord where it is likely they will trip
the boundary layer prematurely.

I've gone through the exercise of designing, fabricating, and
installing a complete airbrake system, and I am so looking forward to
someday making another glider without them.

The biggest downside to flaps is that they are hard to train for,
since there are few two-seaters that have them. And too many gliders
that do have them (I'm looking at you, SGS 1-35), don't have enough of
them, so it's too easy to float down the runway. Flaps that go to only
60 degrees aren't enough; it takes at least 85 to reliably kill the
float and get onto the ground with authority.

The secret to making flaps work is feed-forward. You increase or
decrease pressure on the stick at the same time as you change the flap
setting, in an open-loop fashion. Only then do you close the loop and
refine the pitch pressure based on feedback from the various
indicators (ASI reading, wind noise, deck angle, etc).

If you try to do it completely closed-loop, that is, by changing the
flaps, waiting for signals that your speed is changing, and then
adjusting the pitch in response to the signals, you can end up chasing
the signals right out of the envelope. That's bad, and too many
inexperienced people try it and decide that it can't be done at all.

Thanks, Bob K.

[Tony[_5_]]

> The biggest downside to flaps is that they are hard to train for,
> since there are few two-seaters that have them. And too many gliders
> that do have them (I'm looking at you, SGS 1-35), don't have enough of
> them, so it's too easy to float down the runway. Flaps that go to only
> 60 degrees aren't enough; it takes at least 85 to reliably kill the
> float and get onto the ground with authority.

Bob I've got to send you a picture of the NG-1 with full flaps out. In
fact I need to shoot some landings in it sometime and get some photos
of it from the ground. That thing is impressive! I'm pretty sure the
handle is limited to about 60 degrees or so but that is more than
enough flap. In fact it takes about all the strength in my left arm
to get that much flap at a typical 60 mph approach speed. The flaps
are the same as a BG-12/16 and run from the root to the aileron. On
the few full flap approaches i've done SeeYou has shown an L/D of
somewhere around 5.

[Wayne Paul]

Due to the lack of a "large span" trainer, Bob K developed the following
page to assist Schreder sailplane owners make the transition.
http://www.soaridaho.com/Schreder/Stories/Preparing_for_first_HP_flight.htm

Even though the page was designed for HPs, it applies to any flaps-only
sailplane.

Here are a couple other landing videos.
http://www.youtube.com/watch?v=BC55ikXmo5I
http://www.youtube.com/watch?v=19uZV4wH00

Wayne
HP-14 "6F"
http://tinyurl.com/N990-6F



"Tony" wrote in message
...

> The biggest downside to flaps is that they are hard to train for,
> since there are few two-seaters that have them. And too many gliders
> that do have them (I'm looking at you, SGS 1-35), don't have enough of
> them, so it's too easy to float down the runway. Flaps that go to only
> 60 degrees aren't enough; it takes at least 85 to reliably kill the
> float and get onto the ground with authority.

Bob I've got to send you a picture of the NG-1 with full flaps out. In
fact I need to shoot some landings in it sometime and get some photos
of it from the ground. That thing is impressive! I'm pretty sure the
handle is limited to about 60 degrees or so but that is more than
enough flap. In fact it takes about all the strength in my left arm
to get that much flap at a typical 60 mph approach speed. The flaps
are the same as a BG-12/16 and run from the root to the aileron. On
the few full flap approaches i've done SeeYou has shown an L/D of
somewhere around 5.

[Wayne Paul]

The second link should be
http://www.youtube.com/watch?v=19uZV4wH00U


"Wayne Paul" wrote in message
m...

Due to the lack of a "large span" trainer, Bob K developed the following
page to assist Schreder sailplane owners make the transition.
http://www.soaridaho.com/Schreder/Stories/Preparing_for_first_HP_flight.htm

Even though the page was designed for HPs, it applies to any flaps-only
sailplane.

Here are a couple other landing videos.
http://www.youtube.com/watch?v=BC55ikXmo5I
http://www.youtube.com/watch?v=19uZV4wH00

Wayne
HP-14 "6F"
http://tinyurl.com/N990-6F



"Tony" wrote in message
...

> The biggest downside to flaps is that they are hard to train for,
> since there are few two-seaters that have them. And too many gliders
> that do have them (I'm looking at you, SGS 1-35), don't have enough of
> them, so it's too easy to float down the runway. Flaps that go to only
> 60 degrees aren't enough; it takes at least 85 to reliably kill the
> float and get onto the ground with authority.

Bob I've got to send you a picture of the NG-1 with full flaps out. In
fact I need to shoot some landings in it sometime and get some photos
of it from the ground. That thing is impressive! I'm pretty sure the
handle is limited to about 60 degrees or so but that is more than
enough flap. In fact it takes about all the strength in my left arm
to get that much flap at a typical 60 mph approach speed. The flaps
are the same as a BG-12/16 and run from the root to the aileron. On
the few full flap approaches i've done SeeYou has shown an L/D of
somewhere around 5.

[BobW]

>
> Btw, the distance of the ground run after touchdown has little to do
> with flaps & airbrakes - it's a function of the speed at touch down,
> and your gross weight.
>

Ah, the potential fuzziness of free, condensed, advice!

While some of the above statement is absolutely correct, specifically the,
"...it's a function of the speed at touch down, and your gross weight" bit,
the, "Btw, the distance of the ground run after touchdown has little to do
with flaps & airbrakes..." lead-in may be just a tad misleading for readers
either lacking the specific engineering background, or, otherwise new to flaps.

Because the large-deflection landing flaps used on some sailplanes definitely
do increase lift, this gives Joe Interestedly-Capable Glider Pilot the
*option* of consequently touching down at a slower speed than would otherwise
be safely possible without the flaps' presence. Hence I disagree with the
lead-in statement, IF we presume Joe Glider Pilot is interested in learning
how to get the most (i.e. shortest) landing performance from the glider.

To this point, considering the lead-in video of this thread,I dare say few
gliders of any semi-modern ilk would be capable of touching down and rolling
to a halt, on a paved surface, in a(n ~)5-knot headwind in *only* 300' (twice,
so it might not have been pure luck!) withOUT using that flap-specific
advantage. Kinetic energy remaining after touchdown of a landing glider, after
all, is proportional to speed *squared*, while also being proportional to
touchdown weight (not squared).

Quibblingly,
Bob W.

[BobW]

On 8/11/2011 8:01 AM, Tony wrote:
>> The biggest downside to flaps is that they are hard to train for,
>> since there are few two-seaters that have them. And too many gliders
>> that do have them (I'm looking at you, SGS 1-35), don't have enough of
>> them, so it's too easy to float down the runway. Flaps that go to only
>> 60 degrees aren't enough; it takes at least 85 to reliably kill the
>> float and get onto the ground with authority.
>
> Bob I've got to send you a picture of the NG-1 with full flaps out. In
> fact I need to shoot some landings in it sometime and get some photos
> of it from the ground. That thing is impressive! I'm pretty sure the
> handle is limited to about 60 degrees or so but that is more than
> enough flap. In fact it takes about all the strength in my left arm
> to get that much flap at a typical 60 mph approach speed. The flaps
> are the same as a BG-12/16 and run from the root to the aileron. On
> the few full flap approaches i've done SeeYou has shown an L/D of
> somewhere around 5.

Using crude distance measuring methodology (altimeter for vertical/paced-off
distance for horizontal), I eventually concluded the HP-14 I flew, achieved a
full-flap final-approach L/D, at 45 knots indicated, of somewhere between 3:1
and 1:1, the latter number being easily approached in even the lightest
headwind. I was simply curious, and didn't really care what the 'real' number
was, once it became (more or less instantly [happy memory!]) apparent that the
risk of undershooting in such an immensely 'approach capable' ship was
non-existent.

Nonetheless, despite the immense drag of that particular ship's
fully-deflected flaps, it remained possible for Joe Pilot to 'throw away'
some/all of the flaps' short-field landing capability by flaring 'too fast,'
in which case - as others have noted the possibility of doing - you *would*
float long and far in ground effect. I don't mean to suggest that every
flare/landing need/ought to be a low-energy affair, but if you're flying a
large-deflection-landing-flapped ship and routinely taking a longer distance
to flare, touchdown and roll-out than your buddies in otherwise similar
spoilered ships, you might want to continue learning how to safely extract the
unused landing performance that *does* reside in your ship.

Regards,
Bob W.

[BobW]

On 8/9/2011 10:19 PM, Bruce Hoult wrote:
> On Aug 2, 2:15 pm, > wrote:
>> As for the rollout, how many 1-26 drivers
>> routinely roll no more than 300 feet on a hard surface after touchdown? (And
>> how long does your skid plate last?)
>
> I haven't flown one of those in anger, but most of my genuine landouts
> have been in a PW5.
>
> I always pace out the distances afterwards. The usual figures are
> about 30 paces from a standard cattle farm fence to the main wheel
> touchdown point, and another 30 paces to the point where I'm stopped.
>
> If I call the paces 1m each then that's 200 feet -- from the fence,
> not from touchdown.

Pacing off - or otherwise striving to find some realistic method of
quantifying - one's landing rolls is a highly worthwhile activity, whether at
the gliderport (establishes one's required-field-length 'baseline'), or
eventually in fields (the field distance *will* be shorter due to the higher
drag of the unpaved surface). I usually found my 15-meter Zuni's off-field
rolls ranged from 150' to 200', probably averaging 180'. Field surfaces ranged
from plowed/disked/dry fields (my personal favorite) to hard-packed dirt
(occasionally) and reverting-to-prairie (once). The one G-102 (w. 2 aboard)
OFL I made in a plowed/disked/dry field, albeit very slightly downhill but
into a good breeze, paced out at 220'. All those distances are for summer
conditions at ~5,000' msl. They would've all been less at sea-level, I reckon.

>
> Most of the rest of my landouts were in a Club Libelle. I'd say the
> distances were quite similar. It, of course, has speed limiting
> trailing edge airbrakes, which also have enough flap effect to lower
> the stall by ~5 knots.
>
And it's that stall-speed-lowering capability I so love about landing flaps
(and their close cousins found on some Glasflugel & Schempp-Hirth designs),
when it comes to reducing off-field roll-out risks!
>
>> IMHO, large deflection landing flaps on gliders are the best kept sailplane
>> secret in the last half century.
>
> I'd love to have some! But the trailing edge brakes as on the Club
> Libelle, Hornet, Mosquito and I think also the Mini Nimbus and early
> Ventus seem to give most of the same benefits, plus some extra ones.

Lacking any experience with those designs' 'flaplike' landing aids, I've
resorted to picking pilots' brains whenever I could, trying to get a handle on
the ships' drag-devices' pros & cons. One of my broad-brush, tentative,
conclusions eventually became few 'club-based' pilots ever really learned (or
strove to learn?) how to consistently extract the lowest energy touchdowns
from the devices. The conclusion was based on probing, trying to understand
the pilots' knowledge limits (both practical and theoretical), and then - when
I could - continuing to watch their landings.

FWIW, I routinely thought and flew as if the biggest 'unknown risk', directly
influence-able by me, in soaring was off-field landings, and - once committed
to a given field - the most pertinent thing I could do to minimize the
landing-surface-related 'unknowns risk' was to achieve as short a rollout as
safely possible. Hence the theoretical attraction to me of landing flaps.
Learning their 'unanticipated benefits' was pure gravy!

Regards,
Bob W.

[Tony[_5_]]

lower gross weight is also a great way to lower the stall speed and
shorten the ground roll. typical off field distances from first
impression in the dirt to stop is around 100 feet (30ish paces) in the
600 lb all up Cherokee. of course that light weight might also be
part of why I find yourself in fields so often...

Bob - found a couple of itty bitty tears in the fabric from the last
field at Dalhart. still way better than that piece of steel, which is
still riding in the bed of my pickup!

[jim wynhoff]

On Aug 11, 3:58*pm, BobW > wrote:
> On 8/9/2011 10:19 PM, Bruce Hoult wrote:
>
> > On Aug 2, 2:15 pm, > *wrote:
> >> As for the rollout, how many 1-26 drivers
> >> routinely roll no more than 300 feet on a hard surface after touchdown? (And
> >> how long does your skid plate last?)
>
> > I haven't flown one of those in anger, but most of my genuine landouts
> > have been in a PW5.
>
> > I always pace out the distances afterwards. The usual figures are
> > about 30 paces from a standard cattle farm fence to the main wheel
> > touchdown point, and another 30 paces to the point where I'm stopped.
>
> > If I call the paces 1m each then that's 200 feet -- from the fence,
> > not from touchdown.
>
> Pacing off - or otherwise striving to find some realistic method of
> quantifying - one's landing rolls is a highly worthwhile activity, whether at
> the gliderport (establishes one's required-field-length 'baseline'), or
> eventually in fields (the field distance *will* be shorter due to the higher
> drag of the unpaved surface). I usually found my 15-meter Zuni's off-field
> rolls ranged from 150' to 200', probably averaging 180'. Field surfaces ranged
> from plowed/disked/dry fields (my personal favorite) to hard-packed dirt
> (occasionally) and reverting-to-prairie (once). The one G-102 (w. 2 aboard)
> OFL I made in a plowed/disked/dry field, albeit very slightly downhill but
> into a good breeze, paced out at 220'. All those distances are for summer
> conditions at ~5,000' msl. They would've all been less at sea-level, I reckon.
>
>
>
> > Most of the rest of my landouts were in a Club Libelle. I'd say the
> > distances were quite similar. It, of course, has speed limiting
> > trailing edge airbrakes, which also have enough flap effect to lower
> > the stall by ~5 knots.
>
> And it's that stall-speed-lowering capability I so love about landing flaps
> (and their close cousins found on some Glasflugel & Schempp-Hirth designs),
> when it comes to reducing off-field roll-out risks!
>
>
>
> >> IMHO, large deflection landing flaps on gliders are the best kept sailplane
> >> secret in the last half century.
>
> > I'd love to have some! But the trailing edge brakes as on the Club
> > Libelle, Hornet, Mosquito and I think also the Mini Nimbus and early
> > Ventus seem to give most of the same benefits, plus some extra ones.
>
> Lacking any experience with those designs' 'flaplike' landing aids, I've
> resorted to picking pilots' brains whenever I could, trying to get a handle on
> the ships' drag-devices' pros & cons. One of my broad-brush, tentative,
> conclusions eventually became few 'club-based' pilots ever really learned (or
> strove to learn?) how to consistently extract the lowest energy touchdowns
> from the devices. The conclusion was based on probing, trying to understand
> the pilots' knowledge limits (both practical and theoretical), and then - when
> I could - continuing to watch their landings.
>
> FWIW, I routinely thought and flew as if the biggest 'unknown risk', directly
> influence-able by me, in soaring was off-field landings, and - once committed
> to a given field - the most pertinent thing I could do to minimize the
> landing-surface-related 'unknowns risk' was to achieve as short a rollout as
> safely possible. Hence the theoretical attraction to me of landing flaps.
> Learning their 'unanticipated benefits' was pure gravy!
>
> Regards,
> Bob W.


Since I know SOMEONE will call you on it..... It must have been pretty
cozy in the "G102 w/2 on board"! I assume that was a typo, and you
meant G103. G-102 (w. 2 aboard)
Not that I'll ever be able to afford a different glider, but I would
love to have a 'flap only' ship. Simpler (hence lighter) wing, shorter
roll -outs, etc. What's not to like?

[BobW]

On 8/11/2011 6:59 PM, jim wynhoff wrote:
<Major snip...>
>>
>> Pacing off - or otherwise striving to find some realistic method of
>> quantifying - one's landing rolls is a highly worthwhile activity, whether at
>> the gliderport (establishes one's required-field-length 'baseline'), or
>> eventually in fields (the field distance *will* be shorter due to the higher
>> drag of the unpaved surface). I usually found my 15-meter Zuni's off-field
>> rolls ranged from 150' to 200', probably averaging 180'. Field surfaces ranged
>> from plowed/disked/dry fields (my personal favorite) to hard-packed dirt
>> (occasionally) and reverting-to-prairie (once). The one G-102 (w. 2 aboard)
>> OFL I made in a plowed/disked/dry field, albeit very slightly downhill but
>> into a good breeze, paced out at 220'. All those distances are for summer
>> conditions at ~5,000' msl. They would've all been less at sea-level, I reckon.

<Snip...>
>>
>>
>> FWIW, I routinely thought and flew as if the biggest 'unknown risk', directly
>> influence-able by me, in soaring was off-field landings, and - once committed
>> to a given field - the most pertinent thing I could do to minimize the
>> landing-surface-related 'unknowns risk' was to achieve as short a rollout as
>> safely possible. Hence the theoretical attraction to me of landing flaps.
>> Learning their 'unanticipated benefits' was pure gravy!
>>
>> Regards,
>> Bob W.
>
>
> Since I know SOMEONE will call you on it..... It must have been pretty
> cozy in the "G102 w/2 on board"! I assume that was a typo, and you
> meant G103. G-102 (w. 2 aboard)
> Not that I'll ever be able to afford a different glider, but I would
> love to have a 'flap only' ship. Simpler (hence lighter) wing, shorter
> roll -outs, etc. What's not to like?

Doh!!!

Indeed, I meant to type, G-103 (w. 2 aboard) not "...G102 (w. two aboard)..."

Bob W.

[T8]

On Aug 11, 8:59*pm, jim wynhoff > wrote:

> Not that I'll ever be able to afford a different glider, but I would
> love to have a 'flap only' ship. Simpler (hence lighter) wing, shorter
> roll -outs, etc. *What's not to like?

I love flaps.

That said, there are gotchas.

Gotcha #1: wind. Cross wind components become scary to unmanageable
much more rapidly in flap only ships. Head wind component is also an
issue. Summary: if wind is about 12 kts or more, you'll wish you were
flying a spoiler equipped ship. 20 kts of wind gets *really* hairy
and best avoided. 25 is getting to undoable.

Gotcha #2: finesse. Those pretty, steep, low energy approaches to 2x
wingspan roll outs require a lot of finesse. This can be in short
supply at the end of a long day. The penalty for lack-of-finesse can
range from an extra 300' of float in ground effect (5 kts too fast in
flare) to over running the whole danged airport. I've seen it happen,
more than once. My first off field landing in the HP-18 took 970 feet
of a 1000 foot field. Urp. After a decade of practice I could
generally spot land and roll out in < 200 feet on tarmac. With no
brakes :-).

Gocha #2a: learning curve. You'll spend a while learning how to land
your new toy at the home drome when you might rather be flying XC.

Gotcha #3: advice. For reasons I have never discovered, people will
feel free to dispense all sorts of "advice" w.r.t. flapped landings
despite having ZERO time in flap only ships. After a while this
becomes more entertainment than gotcha.

Gotch #4: resale. It's a limited market when it's time to sell. Fact
o' life.

Gotcha #5: blending with other traffic. This is mostly a contest
concern. In a high density finish environment, we all land like std
class ships because the objective is blending, cooperation,
predictability and efficient parking. A flap only ship *hates* being
treated this way and requires the pilot to be about 30 seconds ahead
of the airplane to make it work at all. Add a runway incursion or
gear up landing ahead of you and the flapped ship pilot may not be
able to adjust. When I few the '18 in contests I dreaded mass
landings, would sometimes head for a different part of the airport if
available just so I could fly a comfortable, safe, low energy
approach.

The ideal solution imo is landing flaps plus spoilers (now you know
one reason I own an ASW-20B). The 20B has only about 40 degrees of
landing flap and carries a lot more energy at touchdown than a 90
degree flap only ship, but I can put it right where I want it in a lot
more wind, or in a crowded traffic pattern. Good brake mostly makes
up for 10 kts higher touchdown speed.

-Evan Ludeman / T8

[AGL]

> I love flaps.
>
> That said, there are gotchas.
>
> Gotcha #1: <SNIP> etc.


Well put, especially the comment about thinking far ahead. :-)

You get to learn to fly 10 different airplanes all on the same flight
because the characteristics change so much depending on the flap
setting.

After flying my 1-35 for a few years I have to think really hard
flying anything else because I'm used to being able to fly like a
brick on final instead of smoking/floating/spoilering in on big L/D
numbers.

I like how on final the world opens up like an IMAX screen and people
come running to the side of the runway in horror to watch as I come in
like a lawn dart until the flare. :-)

After the endless advice recieved, and numerous so-so landings
listening to it, the method outlined in the POM works best.

AGL

[BobW]

On 8/14/2011 11:53 AM, T8 wrote:
> On Aug 11, 8:59 pm, jim > wrote:
>
>> Not that I'll ever be able to afford a different glider, but I would
>> love to have a 'flap only' ship. Simpler (hence lighter) wing, shorter
>> roll -outs, etc. What's not to like?
>
> I love flaps.
>
> That said, there are gotchas.
>
"Roger mosta what T8 notes/discusses below." As always, the devil is in the
details (cut-n-inserted in a coupla places), and hopefully a lurker or two
following this thread may be sussing some potentially useful insights.

> Gotcha #1: wind. Cross wind components become scary to unmanageable
> much more rapidly in flap only ships. Head wind component is also an
> issue. Summary: if wind is about 12 kts or more, you'll wish you were
> flying a spoiler equipped ship. 20 kts of wind gets *really* hairy
> and best avoided. 25 is getting to undoable.

Knowing your previous ship was an HP-18, but not knowing anything about its
flap-operating mechanism, I have to ask:

Q1: "Why do you think the above crosswind bit was true in your bird?"

Reason I ask is my Zuni's flaps can be dumped from full to zero-to-negative
(which firmly plants its non-steerable tailwheel), as fast as I can move my
forearm in an arc of ~45-degrees. I completely agree a strong crosswind is no
place for a full-flap, low-energy, touchdown attempt, but in the Zuni, strong
crosswinds effectively transform it into a spoilered ship insofar as my
landing technique,and touchdown energy is concerned. IOW, I simply use less
flap, come in faster and perform wheel landings; works fine in the ship. The
strongest direct X-wind ever landed in was an estimated 25-30 knots at
90-degrees, a few minutes after a buddy endured the same in his St'd Cirrus.
Comparing notes afterward, I opted for ~5 knots higher short-final speed than
he (75 knots as I recall, but I'd have to dig into the logbooks). His arc from
runway (taxiway, actually - no lights!) heading, consumed about 5-8
perpendicular feet, mine roughly twice that, due mostly I figured to the
higher touchdown speed and lousier pilot. In my HP-14, I'd've comfortably
landed directly into the wind across the (small) tiedown ramp, because of its
more effective flaps and wheel brake. Given the 18-inch drop-off at the far
end of the ramp, I felt the Zuni was dodgy.

Q2: What haven't I experienced insofar as landing into ==> *direct* <==,
strong, headwinds in either the HP or Zuni? "The more the easier," has been
my experience, especially in the HP which - with full flaps - descended so
steeply that the existence of significant wind shear (pretty normal at
Boulder, CO, in strong wind conditions) never affected airspeed, but simply
shifted the roundout point by a few feet. At first I was highly skeptical
about that last phenomenon, but after experiencing it multiple times, I became
a believer. (Think/imagine wind/flight vectors...) Not/much-less true in the
Zuni, with its nearer-to-horizontal flight path.

>
> Gotcha #2: finesse. Those pretty, steep, low energy approaches to 2x
> wingspan roll outs require a lot of finesse. This can be in short
> supply at the end of a long day. The penalty for lack-of-finesse can
> range from an extra 300' of float in ground effect (5 kts too fast in
> flare) to over running the whole danged airport. I've seen it happen,
> more than once. My first off field landing in the HP-18 took 970 feet
> of a 1000 foot field. Urp. After a decade of practice I could
> generally spot land and roll out in< 200 feet on tarmac. With no
> brakes :-).

"Roger that," and, "I completely concur," finesse-wise. I soon (two seasons?
20-30 landing attempts?) came to believe that flaps actively reward 'proper'
(i.e. speed-finessed) pattern/roundout/touchdown techniques, while actively
discouraging 'hamfistedness.' (Who's not a fan of precise speed control in a
landing pattern? Personally I strive to maintain mine within a needle's width
- and will settle for two if it's noticeably thermic - on the ASI...whether in
a flapped ship or a spoilered one.) In any event, think 'getting to Carnegie
Hall' - practice, practice practice!

>
> Gocha #2a: learning curve. You'll spend a while learning how to land
> your new toy at the home drome when you might rather be flying XC.

How Joe Pilot handles this aspect of practicing is undoubtedly influenced by
their soaring site's available non-airport fields. I certainly don't
discourage home-field practice, but in my neck of the woods, once I'd
established confidence in my ability to 'roughly' judge a glidepath, and, had
established the 'minimum field length' I needed (in the Zuni, initially a
'grossly conservative' 2,000' my first two summers; afterwards, up to 1,000'
if I was rusty), I'd fly XC, limiting myself only by remaining within reach of
my piloting-currency-defined, minimum field length fields.

>
> Gotcha #3: advice. For reasons I have never discovered, people will
> feel free to dispense all sorts of "advice" w.r.t. flapped landings
> despite having ZERO time in flap only ships. After a while this
> becomes more entertainment than gotcha.
>
> Gotch #4: resale. It's a limited market when it's time to sell. Fact
> o' life.

"Roger 3 & 4!"

>
> Gotcha #5: blending with other traffic. This is mostly a contest
> concern. In a high density finish environment, we all land like std
> class ships because the objective is blending, cooperation,
> predictability and efficient parking. A flap only ship *hates* being
> treated this way and requires the pilot to be about 30 seconds ahead
> of the airplane to make it work at all. Add a runway incursion or
> gear up landing ahead of you and the flapped ship pilot may not be
> able to adjust. When I few the '18 in contests I dreaded mass
> landings, would sometimes head for a different part of the airport if
> available just so I could fly a comfortable, safe, low energy
> approach.

Never having flown 'real contests,' I can still relate to the 'sheer, utter
differences' in pattern-profile between a large-deflection-flapped glider and
those with spoilers. Despite the home field being a busy one (parallel glider
runways, with beaucoup glider activity), I 'pretty quickly' learned to strive
for 'I'm the only guy in the pattern' approaches, for multiple reasons. And in
the HP, more than once I intentionally did what you described doing...landed
on 'the generally unused' bits of the runway if I felt it safest. (No need to
be a sheep unless you're born one!)

>
> The ideal solution imo is landing flaps plus spoilers (now you know
> one reason I own an ASW-20B). The 20B has only about 40 degrees of
> landing flap and carries a lot more energy at touchdown than a 90
> degree flap only ship, but I can put it right where I want it in a lot
> more wind, or in a crowded traffic pattern. Good brake mostly makes
> up for 10 kts higher touchdown speed.
>
> -Evan Ludeman / T8

Funnily enough my short list at the time I purchased the Zuni included also
the PIK-20 A/B and AS W-20A. Couldn't really afford the Schleicher, but my
engineer brain sure liked what they'd done with it in approach-drag-options.
Given: a) the fact factory management saw fit to go the (undoubtedly
manufacturing-complex) road of dually-functional drag devices, and b) the
sales success of the ship, part of me has long been puzzled why they didn't
continue down that path. Over the years, I've encountered a number of AS W-20A
pilots who eschewed their large deflection flaps in favor of the spoilers,
often (as I poked my nose into the situations) from what I'll call 'flap fear.'

Bob - options are good! - W.

[T8]

On Aug 14, 7:34*pm, BobW > wrote:
> On 8/14/2011 11:53 AM, T8 wrote:

> > Gotcha #1: wind. *Cross wind components become scary to unmanageable
> > much more rapidly in flap only ships. *Head wind component is also an
> > issue. *Summary: if wind is about 12 kts or more, you'll wish you were
> > flying a spoiler equipped ship. *20 kts of wind gets *really* hairy
> > and best avoided. *25 is getting to undoable.
>
> Knowing your previous ship was an HP-18, but not knowing anything about its
> flap-operating mechanism, I have to ask:
>
> Q1: "Why do you think the above crosswind bit was true in your bird?"
>
> Reason I ask is my Zuni's flaps can be dumped from full to zero-to-negative
> (which firmly plants its non-steerable tailwheel), as fast as I can move my
> forearm in an arc of ~45-degrees. I completely agree a strong crosswind is no
> place for a full-flap, low-energy, touchdown attempt, but in the Zuni, strong
> crosswinds effectively transform it into a spoilered ship insofar as my
> landing technique,and touchdown energy is concerned. IOW, I simply use less
> flap, come in faster and perform wheel landings; works fine in the ship.

Ah. Well yes, the HP-18 had, shall we say (as kindly as possible),
"other issues". Among them, a very small tail volume and rather
limited throw on the ruddervators. Certainly a contributing factor.

My only other experience in a flap only ship was in Andre Kruchkoff's
"SHP-1", a beautiful tee tail bird with HP-14 wings/flaps. I never
flew that in high wind, but relative to the '18, it was a complete
pussycat. One of the neatest ships I've ever flown. That ship could
be spot landed and rolled to a stop in less than 100 feet... with a
tail skid, but no brakes.

-Evan Ludeman / T8