Landing Flap Video

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

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.

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.

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/St..._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.

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/St..._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.

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.

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.

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.

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!

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?