Landing Flap Video

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.

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

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

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.