reverse the last thing you did.

[mart]

I had an interesting talk in Narromine last week with a local
instructor about my LS6. I bought it because I thought it to have few
vices.

He knew one.One that almost killed him.

Coming back after a racing task he selected +10 flaps, plenty enough
to land with, especially when it's a bit windy.
On final he pulled full airbrakes after gong through some lift on
base. This causes the flaps to come along, out +10 towards Landing
flap. This happens automatically. It only doesn't lock automatically
in that case. When about 20 feet of the deck he put half his airbrakes
away for a smooth landing.

So far, that is what I do as well.

Now the problems started. While putting the airbrakes away the flaps
slipped to negative. Not very handy at 20 feet and relatively slow.
The glider promptly stalled.

He than did what he was thought by a test pilot." If everything goes
to ****, reverse the last thing you have done."

So contrary to what you would normally do when stalled, which is to
push the nose over , he pulled the brakes again, which in turn pulled
the flaps out again. He said that it saved his bacon. Took out the
undercarriage and hurt his back, but he walked away.

I've heard the Ventus 1 suffers from the same problem. Maybe some
other gliders as well. I thought I should share it with you just in
case.

cheers,

Mart

VH-NII

[silentpilot]

On Jan 26, 5:57*am, mart > wrote:
> I had an interesting talk in Narromine last week with a local
> instructor about my LS6. I bought it because I thought it to have few
> vices.
>
> He knew one.One that almost killed him.
>
> Coming back after a racing task he selected +10 flaps, plenty enough
> to land with, especially when it's a bit windy.
> On final he pulled full airbrakes after gong through some lift on
> base. This causes the flaps to come along, out +10 towards Landing
> flap. This happens automatically. It only doesn't lock automatically
> in that case. When about 20 feet of the deck he put half his airbrakes
> away for a smooth landing.
>
> So far, that is what I do as well.
>
> Now the problems started. While putting the airbrakes away the flaps
> slipped to negative. *Not very handy at 20 feet and relatively slow.
> The glider promptly stalled.
>

I do not believe this story.............
A glider that changes flaps settings back and forth by using spoilers?
I would suspect this a serious mechanical malfunction/problem
undetected during check up.
If this can happen I would not say it is a glider with a vice......
I would say it is A PIECE OF ****!

[Dave Nadler]

On Jan 26, 5:57*am, mart > wrote:
> I had an interesting talk in Narromine last week with a local
> instructor about my LS6. I bought it because I thought it to have few
> vices.
>
> He knew one.One that almost killed him.
>
> Coming back after a racing task he selected +10 flaps, plenty enough
> to land with, especially when it's a bit windy.
> On final he pulled full airbrakes after gong through some lift on
> base. This causes the flaps to come along, out +10 towards Landing
> flap. This happens automatically. It only doesn't lock automatically
> in that case. When about 20 feet of the deck he put half his airbrakes
> away for a smooth landing.
>
> So far, that is what I do as well.
>
> Now the problems started. While putting the airbrakes away the flaps
> slipped to negative. *Not very handy at 20 feet and relatively slow.
> The glider promptly stalled.
>
> He than did what he was thought by a test pilot." If everything goes
> to ****, reverse the last thing you have done."
>
> So contrary to what you would normally do when stalled, which is to
> push the nose over , he pulled the brakes again, which in turn pulled
> the flaps out again. He said that it saved his bacon. Took out the
> undercarriage and hurt his back, but he walked away.
>
> I've heard the Ventus 1 suffers from the same problem. Maybe some
> other gliders as well. *I thought I should share it with you just in
> case.
>
> cheers,
>
> Mart
>
> VH-NII

That's not supposed to happen in LS-6, as the flaps
are supposed to catch the detent. But it can happen.
There's some kind of spring that pulls the flap
handle towards the detent; sounds like that isn't
quite right in that particular glider. I owned a
couple of these gliders and always selected full
flap before using spoiler, which prevents this
possibility.

IIRC other gliders that retract flap with retracting
spoiler are:
- early mosquito and mini-nimbus
- Calif A-21
Early Ventus does not have this problem IFF
proper flap detect is selected prior using
the spoilers.

Any others ?
Hope that helps someone out there,
Best Regards, Dave "YO electric"

[Bob Kuykendall]

On Jan 26, 4:55*am, silentpilot > wrote:

> I do not believe this story.............
> A glider that changes flaps settings back and forth by using spoilers?

Yes, that's the way the LS6 works. The flap and airbrake handles are
intertwined such that application of airbrakes prevents the
simultaneous use of negative flaps. Under most circumstances it works
pretty well. In this instance it did not function as intended.

> If this can happen I would not say it is a glider with a vice......
> I would say it is A PIECE OF ****!

Wow, all-caps invective. How insightful.

Thanks, Bob K.

[Bob Whelan[_3_]]

mart wrote:
> <Snip...>
>
> Now the problems started. While putting the airbrakes away the flaps
> slipped to negative. Not very handy at 20 feet and relatively slow.
> The glider promptly stalled.

You've probably already gleaned 'the obvious' lessons from this
incident, but - hoping to not be beating a dead horse for others who may
not yet have - here's my take. (A 'take' wholly ignorant of how the
LS-6's flap/airbrake system is *supposed* to work, incidentally...but a
take with >2k hours on 3-different flaps-only gliders, meaning each had
differing 'monkey motion' mechanical/hydraulic systems powering the
flaps, & only one ship of which had reflexing flaps...)

In a nutshell, never assume you know everything about how a system - any
system - is supposed to work without spending 'considerable time'
physically examining its realities. Of course, reading about it is good
too...but not wholly sufficient.

Never carry a package by the string...by which I'm suggesting all
mechanical locks should be viewed with a jaundiced eye, whether a gear
downlock, flap detent, or whatever. Locks wear. Some aren't even locks,
but rather 'suspenders' to another 'belt' somewhere. (My current ship's
'apparent' gear downlock falls into that category, according to the
designer.) Don't court failure...but be prepared for it. Use
'suspenders' where you can.
- - - -

>
> He than did what he was thought by a test pilot." If everything goes
> to ****, reverse the last thing you have done."

Excellent advice...if a person has the time/wits to apply it.
- - - -

>
> So contrary to what you would normally do when stalled, which is to
> push the nose over , he pulled the brakes again, which in turn pulled
> the flaps out again. He said that it saved his bacon. Took out the
> undercarriage and hurt his back, but he walked away.

Even in the absence of being able to deploy spoilers (and - he hoped -
flaps again prior to contacting the ground, i.e. your adviser), my
working conclusion is radically changing fuselage pitch angle (via
radical stick movements) near the ground is generally A Really Bad Thing
To Do. Even if a thoughtful person gets away with it without pranging
something, s/he'll come away with a deeper understanding of what happens
in the short term when one reduces wing angle of attack. Stated another
way, doing this near the ground is a 'good' way to learn that stick
*directly* controls angle of attack, and only indirectly, speed. Guess
which one changes first when you put stick forward close to the deck?

A stall at 20-feet agl is basically unrecoverable via stick input *only*
for the gliders we fly. The only salvation *might* be changing wing
angle of attack via camber change (if an option). In the absence of
complicating flaps, closing spoilers is advisable, too, natch.

Your adviser 'got away with' what would appear to be a rare-enough
situation, to be sure...

Had he not known of the 'reverse what you last did' advice, and instead
attempted to recover via forward stick, my money woulda been placed on
him whacking the ground at a steeper deck angle, harder.

And with the advantage of time and hindsight, had he simply pulled on
flaps (rather than hoping they came back with spoiler activation), it's
*possible* his arrival might have been less abrupt. As always, the devil
is in the details. Only thoughtfully checking your ship can allow you to
most sensibly decide for yourself which approach would have been 'ideal'
in your adviser's situation.
- - - -

>
> I thought I should share it with you just in
> case.
>
> cheers,
>
> Mart
>
> VH-NII

Thanks for sharing!!!

Regards,
Bob W.

[jcarlyle]

Bob,

In the spirit of getting to know how things work, could you please
elaborate on "Some aren't even locks, but rather 'suspenders' to
another 'belt' somewhere. (My current ship's 'apparent' gear downlock
falls into that category, according to the designer.)"

Thanks!

-John

On Jan 26, 12:29 pm, Bob Whelan > wrote:
> In a nutshell, never assume you know everything about how a system - any
> system - is supposed to work without spending 'considerable time'
> physically examining its realities. Of course, reading about it is good
> too...but not wholly sufficient.
>
> Never carry a package by the string...by which I'm suggesting all
> mechanical locks should be viewed with a jaundiced eye, whether a gear
> downlock, flap detent, or whatever. Locks wear. Some aren't even locks,
> but rather 'suspenders' to another 'belt' somewhere. (My current ship's
> 'apparent' gear downlock falls into that category, according to the
> designer.) Don't court failure...but be prepared for it. Use
> 'suspenders' where you can.

[JS]

Mart et al:
Having probably 800 hours in LS-6, I never had the flaps jump toward
negative when they were positive.
This will however happen in a flapped Schempp glider if you have
allowed the flap selector track to wear and not replaced it. It does
not happen if the track is as new. This happened to me on short final
in a N3. Don't panic, fly the glider, everything is fine. Replace the
track.
The best possibility I can think of for the LS-6 is that something
(certainly not winter clothing at Narromine, this time of year) was
pushing outward on the flap handle to prevent it from latching into
the ratchet track. Did the pilot in the story keep a water bottle or
any other supplies on the left side of the cockpit? Was he overweight
or overdressed? If so, that is likely the "POS" that some would,
having no experience in LS flapped ships, blame the glider for.
The one place I found the airbrake/flap interconnect in LS- 6 (LS-3
works the same) to be a problem was in wave. You can not use much
airbrake to prevent yourself from climbing above 17,999' or you'll go
over flap operating speed in a hurry. It becomes a legal problem,
which is usually preferred to a mechanical problem.
Jim

[silentpilot]

On Jan 26, 11:25*am, Bob Kuykendall > wrote:
> On Jan 26, 4:55*am, silentpilot > wrote:

> > If this can happen I would not say it is a glider with a vice......
> > I would say it is A PIECE OF ****!
>
> Wow, all-caps invective. How insightful.
>
> Thanks, Bob K.


all-caps invective......
YES AND NO!
Maybe to somebody that knows the modern funny song
PIECE OF **** CAR by Adam Sandler
this may only "sound" sarcastic.
I hope one day somebody will write/translate/copy a funny song
PIECE OF **** GLIDER.
I apologize to everybody else!
Happy Landings!

[Tony[_5_]]

> this may only "sound" sarcastic.
> I hope one day somebody will write/translate/copy a funny song
> PIECE OF **** GLIDER.
> I apologize to everybody else!
> Happy Landings!

piece of s**t glider, i got a piece of s**t glider
that f***ing pile of s**t, it never gets me very far
my gliders a piece of s**t cause the finish is f****ing shot
whenever i fly my glider, i have to swear a lot (its a piece of s**t)

i can't see through the canopy, cause my crew wiped with a dry rag
and the interior smells real bad cause the relief tube caught a snag
(its a piece of s**t)

its got no ILEC SN10, just a noncompensated vario
oh what i'd give for an ipaq, or at least maybe audio
and its got no f***ing airbrake, i'm always way out of control
every time i enter the patter i hear 'HEY, WATCH IT ***HOLE"

oh what the f*** did i do, what the f**** did i do, what the f*** did
i do, to get stuck with you
your wings are too short for FAI, the L/D is under 10, but im too
broke to buy anything new. oh f*** me!

im way too much drag on tow, the airplane always stalls
if i ever landed back at the airport the pilot would kick me in the
balls (ouch ouch ouch)
the canopy lock is busted, gotta use a f***ing coat hangar,
if a girl ever sees my glider theres no chance i'd ever bang her.


that pretty much cover it Paul??

[nic]

I fly a LS-3A, and I noticed early on that you must have 20 degrees
flap to have full spoiler. I played with spoiler flap combination on
my first flight and noticed that it is possible to release the flaps
from the detent while deploying spoiler and go to negative flap by
accident. I usually just leave the flap in 20 degrees for landing.
It is possible to use less flap while landing, but you must make sure
to keep the spoiler handle as vertical as possible if you go to full
spoiler and then reduce the amount of spoiler. I use the back of my
hand to keep the flap in the notch I select. It is a weird system as
the spoiler driver slides inside the flap driver, so if you cannot
have any spoiler with full negative flap. Also, as you deploy the
spoiler the flap moves to the positive positions. I find 20 degree
flap is a lot of drag and you don't need a lot of spoiler. I've tried
landing with 10 degrees flap and it is possible to go to full spoiler
and back to 10 degree flap, but you must pay attention to the flap
handle position. Just leave it in 20 degrees for landing and come in
high.

Ed Gaddy

[hretting]

If you wrote the glider tune, you should get an award of some kind.
It epitomizies all the suffering of those who are forced to fly crap
or are talked into buying an "Elmira" utility sled.
Simply acknowledging the existance of these poor creatures gives hope
that the possibility of advancement does exist.

"If not for those on the bottom, not I see the top"

R

[Tony[_5_]]

On Jan 26, 6:51*pm, hretting > wrote:
> If you wrote the glider tune, you should get an award of some kind.
> It epitomizies all the suffering of those who are forced to fly crap
> or are talked into buying an "Elmira" utility sled.
> Simply acknowledging the existance of these poor creatures gives hope
> that the possibility of advancement does exist.
>
> "If not for those on the bottom, not I see the top"
>
> R

i made it up all on my own. ode to my car is one of my favorite adam
sandler tunes

[Eric Greenwell]

mart wrote:
> I had an interesting talk in Narromine last week with a local
> instructor about my LS6. I bought it because I thought it to have few
> vices.
>
> He knew one.One that almost killed him.
>
> Coming back after a racing task he selected +10 flaps, plenty enough
> to land with, especially when it's a bit windy.
> On final he pulled full airbrakes after gong through some lift on
> base. This causes the flaps to come along, out +10 towards Landing
> flap. This happens automatically. It only doesn't lock automatically
> in that case. When about 20 feet of the deck he put half his airbrakes
> away for a smooth landing.
>
> So far, that is what I do as well.
>
> Now the problems started. While putting the airbrakes away the flaps
> slipped to negative. Not very handy at 20 feet and relatively slow.
> The glider promptly stalled.
The glider did not stall, because the stall attitude with negative flaps
is _very_ nose high; instead, it sank because the lift was reduced when
the flaps went to negative. Had he applied back stick, he would have
decreased the sink rate and, perhaps, hit the ground more slowly.
"Perhaps", because the nose high attitude would cause the tail to hit
first, and that _might_ cause the glider to hit hard on the main gear.
If he'd been 5 feet off the ground instead of 20 feet, that would have
worked fine, especially if he closed the spoilers as a pilot usually
does when the sink rate increases.

Putting the nose forward, then back, might have worked. Hard to say with
out knowing and running the numbers, or trying it!

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

[shkdriver]

;718846']On Jan 26, 6:51*pm, hretting wrote:
If you wrote the glider tune, you should get an award of some kind.
It epitomizies all the suffering of those who are forced to fly crap
or are talked into buying an "Elmira" utility sled.
Simply acknowledging the existance of these poor creatures gives hope
that the possibility of advancement does exist.

"If not for those on the bottom, not I see the top"

R

i made it up all on my own. ode to my car is one of my favorite adam
sandler tunes

Good job, funny take on adam sandler!

Hey, just what is an 'Elmira utility'? Are we talking about SGS's ?
Scott

[Bruce]

Duodiscus - x models on have interconnected landing flap and airbrake,
working in conjunction so that opening airbrake moves landing flap down.

Means that stall speed stays constant with flap proportional to airbrake
at all times. Quite neat especially as it avoids the nose up attitude
typical of non-flap ship.

Bruce


Dave Nadler wrote:
> On Jan 26, 5:57 am, mart > wrote:
>> I had an interesting talk in Narromine last week with a local
>> instructor about my LS6. I bought it because I thought it to have few
>> vices.
>>
>> He knew one.One that almost killed him.
>>
>> Coming back after a racing task he selected +10 flaps, plenty enough
>> to land with, especially when it's p on landinga bit windy.
>> On final he pulled full airbrakes after gong through some lift on
>> base. This causes the flaps to come along, out +10 towards Landing
>> flap. This happens automatically. It only doesn't lock automatically
>> in that case. When about 20 feet of the deck he put half his airbrakes
>> away for a smooth landing.
>>
>> So far, that is what I do as well.
>>
>> Now the problems started. While putting the airbrakes away the flaps
>> slipped to negative. Not very handy at 20 feet and relatively slow.
>> The glider promptly stalled.
>>
>> He than did what he was thought by a test pilot." If everything goes
>> to ****, reverse the last thing you have done."
>>
>> So contrary to what you would normally do when stalled, which is to
>> push the nose over , he pulled the brakes again, which in turn pulled
>> the flaps out again. He said that it saved his bacon. Took out the
>> undercarriage and hurt his back, but he walked away.
>>
>> I've heard the Ventus 1 suffers from the same problem. Maybe some
>> other gliders as well. I thought I should share it with you just in
>> case.
>>
>> cheers,
>>
>> Mart
>>
>> VH-NII
>
> That's not supposed to happen in LS-6, as the flaps
> are supposed to catch the detent. But it can happen.
> There's some kind of spring that pulls the flap
> handle towards the detent; sounds like that isn't
> quite right in that particular glider. I owned a
> couple of these gliders and always selected full
> flap before using spoiler, which prevents this
> possibility.
>
> IIRC other gliders that retract flap with retracting
> spoiler are:
> - early mosquito and mini-nimbus
> - Calif A-21
> Early Ventus does not have this problem IFF
> proper flap detect is selected prior using
> the spoilers.
>
> Any others ?
> Hope that helps someone out there,
> Best Regards, Dave "YO electric"

--- news://freenews.netfront.net/ - complaints: ---

[mart]

Hi All,

Thanks for most responses. I have learned a few things.

About the flaps always being locked, the flap lever moves in a long
slot with on one side the hooks to lock them. They only work in one
direction, to prevent them going forward. That is why the can move out
of lock,backwards, when moving the airbrakes. There is no spring that
pushes them back into the side with the hooks.

I know that this is used by pilots when flying faster then 150km/u or
80 knots with is the point of moving from 0 to -5 flap. Flying a
90knots you might want to use -1 flap to get best performance. Letting
the flaps float makes that happen.

Coming Saturday I will see if I can do a pratice run doing exactly
what happened , only with a bit of height.

Should have flown today..10k base with 8knot climbs. Work got in the
way.

Cheers,

Mart

[Michael Huber]

> The best possibility I can think of for the LS-6 is that something
> (certainly not winter clothing at Narromine, this time of year) was
> pushing outward on the flap handle to prevent it from latching into
> the ratchet track.

I once experienced strange behavior during take off in a glider I had a few
hundred hours in. The trim lever was caught and moved to its back stop by
the band of my wrist watch. I felt something tear on my wrist, a little
later during take off I realized that the trim was completely wrong, but it
took me some time to understand what really happened ...

Michael

[Bob Whelan[_3_]]

jcarlyle wrote:
> Bob,
>
> In the spirit of getting to know how things work, could you please
> elaborate on "Some aren't even locks, but rather 'suspenders' to
> another 'belt' somewhere. (My current ship's 'apparent' gear downlock
> falls into that category, according to the designer.)"
>
> Thanks!
>
> -John
>

I was referring to my Zuni I's (S/N 3) gear downlock system.

For years I believed the primary downlock was 'an LS-like' gas strut in
the system, (probably) backed up by the over-centering action of the
wheel-support structure steel tubing. (It's a *strong* strut.)

Eventually, if I've understood George Applebay (the designer) correctly,
I was informed I had things backward in the sense the gas strut was
intended primarily to help raise the gear, though residual pressure in
up/down positions *does* assist in keeping the geometry unchanging.
There *is* a mechanical uplock, while the downlock was intended to be
the gear geometry in conjunction with braking action.

Because it does me good to believe my primary downlock is still the gas
strut, I treat the gear system as if it is.

Regards,
Bob W.

[jcarlyle]

I understand completely, now - thank you, Bob!

-John

Bob Whelan wrote:
> I was referring to my Zuni I's (S/N 3) gear downlock system.
>
> For years I believed the primary downlock was 'an LS-like' gas strut in
> the system, (probably) backed up by the over-centering action of the
> wheel-support structure steel tubing. (It's a *strong* strut.)
>
> Eventually, if I've understood George Applebay (the designer) correctly,
> I was informed I had things backward in the sense the gas strut was
> intended primarily to help raise the gear, though residual pressure in
> up/down positions *does* assist in keeping the geometry unchanging.
> There *is* a mechanical uplock, while the downlock was intended to be
> the gear geometry in conjunction with braking action.
>
> Because it does me good to believe my primary downlock is still the gas
> strut, I treat the gear system as if it is.

[Dave Nadler]

On Jan 27, 2:37*am, mart > wrote:
> Hi All,
>
> Thanks for most responses. I have learned a few things.
>
> About the flaps always being locked, the flap lever moves in a long
> slot with on one side the hooks to lock them. They only work in one
> direction, to prevent them going forward. That is why the can move out
> of lock,backwards, when moving the airbrakes. There is no spring that
> pushes them back into the side with the hooks.
>
> I know that this is used by pilots when flying faster then 150km/u or
> 80 knots with is the point of moving from 0 to -5 flap. *Flying a
> 90knots you might want to use -1 flap to get best performance. Letting
> the flaps float makes that happen.
>
> Coming Saturday I will see if I can do a pratice run doing exactly
> what happened , only with a bit of height.
>
> Should have flown today..10k base with 8knot climbs. Work got in the
> way.
>
> Cheers,
>
> Mart

In any case, select at least +2 flap before landing;
IIRC this setting will not be pushed further back
when deploying spoilers.
Check it in the cockpit !

Hope this helps,
Best Regards, Dave "YO electric"

[[email protected]]

On Jan 26, 5:57*am, mart > wrote:

>
>
>
>
>
> Now the problems started. While putting the airbrakes away the flaps
> slipped to negative. *Not very handy at 20 feet and relatively slow.
> The glider promptly stalled.
>
> He than did what he was thought by a test pilot." If everything goes
> to ****, reverse the last thing you have done."
>
> So contrary to what you would normally do when stalled, which is to
> push the nose over , he pulled the brakes again, which in turn pulled
> the flaps out again. He said that it saved his bacon. Took out the
> undercarriage and hurt his back, but he walked away.
>
>

>
> Mart
>

I am surprised that only one pilot responded to the misconceptions
exibited it the above post! I tried to respond but for some reason my
posts don't seem to get throught...

Anyway, the misconception is that sudden retraction of flaps will
cause a "stall". And in the case above, that a "non-stall recovery",
"recovered the glider from a stall".

Retracting flaps will DECRERASE the effective angle of attack. If the
glider was not already stalled, DECREASING the angle of attack
certainly will not stall it.

What the sudden flap retraction did however, is change the coeffecient
of lift, which resulted in an imbalance of lift, drag and weight,
which in turn resulted in an acceleration, which was partly
DOWNWARD....

The pilot simply redeployed the flaps, returning the original
coeffecient of lift, which arrested the downward acceleration.
A non-stall recovery, for a non stall problem!

The pilot could have also pulled back on the stick, which might have
restored the balance of lift, drag, and weight, and arrested the high
sink rate. This however, WOULD increase the angle of attack, and
might possibly cause an actual stall if the critical angle was
exceeded.

Cookie

[T8]

On Jan 30, 8:36*am, "
> wrote:

> The pilot could have also pulled back on the stick, which might have
> restored the balance of lift, drag, and weight, and arrested the high
> sink rate. *

No way. He'd have gone in (very) hard on the tail.

It's probably possible to land a 15m glider in negative flap, but
you'd need a final approach speed of 70 kts to do it. From the
description of this incident, it sounds like the pilot was closer to
50 kts and certainly under 55.

You need to keep in mind that flaps change wing incidence, tail
incidence (relative to wing), and especially max CL. All at once.
This pilot made two mistakes (flaps not locked, too slow too high -
accident would not have happened if he hadn't had to close the
spoilers!) and a very clutch response that saved his ass.

Uncommanded flap changes in close proximity to the ground or other
aircraft are life threatening. You need procedures and control locks
that absolutely prevent this.

My $0.02.

-Evan Ludeman (15m guy)

[Brad[_2_]]

On Jan 30, 8:35*am, T8 > wrote:
> On Jan 30, 8:36*am, "
>
> > wrote:
> > The pilot could have also pulled back on the stick, which might have
> > restored the balance of lift, drag, and weight, and arrested the high
> > sink rate. *
>
> No way. *He'd have gone in (very) hard on the tail.
>
> It's probably possible to land a 15m glider in negative flap, but
> you'd need a final approach speed of *70 kts to do it. *From the
> description of this incident, it sounds like the pilot was closer to
> 50 kts and certainly under 55.
>
> You need to keep in mind that flaps change wing incidence, tail
> incidence (relative to wing), and especially max CL. *All at once.
> This pilot made two mistakes (flaps not locked, too slow too high -
> accident would not have happened if he hadn't had to close the
> spoilers!) and a very clutch response that saved his ass.
>
> Uncommanded flap changes in close proximity to the ground or other
> aircraft are life threatening. *You need procedures and control locks
> that absolutely prevent this.
>
> My $0.02.
>
> -Evan Ludeman (15m guy)

I used to rent a C-150. The flap toggle on that airplane was spring
loaded, and if you were not careful, the switch would flip up and
start retracting the flaps after you selected max flap setting. This
happened to me on a short final sometime ago. I had just selected full
flaps, 40 degrees (I think) and had perfect pitch and power for a
touchdown on the numbers. Suddenly it seemed like I was falling out of
the sky.............so I gave more throttle, pitched down a bit more
and then decided I better do a go around. Imagine my surprise when I
noticed the flaps had already retracted!

Brad

[vaughn[_2_]]

"Brad" > wrote in message
...
I used to rent a C-150. The flap toggle on that airplane was spring
loaded, and if you were not careful, the switch would flip up and
start retracting the flaps after you selected max flap setting.

Not just C-150's. Most 172's that I rent also have that same flap toggle. What
were they thinking?

Vaughn

[Andreas Maurer]

On Sat, 30 Jan 2010 08:35:54 -0800 (PST), T8 >
wrote:

>It's probably possible to land a 15m glider in negative flap, but
>you'd need a final approach speed of 70 kts to do it. From the
>description of this incident, it sounds like the pilot was closer to
>50 kts and certainly under 55.

Well, I've already seen an ASW-27 land with fully negative flaps aith
a normal approach speed of about 50-55 kts. Impressive nose-up
attitude, but otherwise unproblematic.

[T8]

On Jan 30, 8:09*pm, Andreas Maurer > wrote:
> On Sat, 30 Jan 2010 08:35:54 -0800 (PST), T8 >
> wrote:
>
> >It's probably possible to land a 15m glider in negative flap, but
> >you'd need a final approach speed of *70 kts to do it. *From the
> >description of this incident, it sounds like the pilot was closer to
> >50 kts and certainly under 55.
>
> Well, I've already seen an ASW-27 land with fully negative flaps aith
> a normal approach speed of about 50-55 kts. Impressive nose-up
> attitude, but otherwise unproblematic.

Sounds a little marginal to me! Glad it was unproblematic.

"70" is just my guess for a safe approach speed in negative flap, with
spoilers out, in a '20 or similar vintage 15m with larger chord
flaps. I've surely never tried this.

-Evan Ludeman / T8

[[email protected]]

On Jan 30, 11:35*am, T8 > wrote:
> On Jan 30, 8:36*am, "
>
> > wrote:
> > The pilot could have also pulled back on the stick, which might have
> > restored the balance of lift, drag, and weight, and arrested the high
> > sink rate. *
>
> No way. *He'd have gone in (very) hard on the tail.
>
> It's probably possible to land a 15m glider in negative flap, but
> you'd need a final approach speed of *70 kts to do it. *From the
> description of this incident, it sounds like the pilot was closer to
> 50 kts and certainly under 55.
>
> You need to keep in mind that flaps change wing incidence, tail
> incidence (relative to wing), and especially max CL. *All at once.
> This pilot made two mistakes (flaps not locked, too slow too high -
> accident would not have happened if he hadn't had to close the
> spoilers!) and a very clutch response that saved his ass.
>
> Uncommanded flap changes in close proximity to the ground or other
> aircraft are life threatening. *You need procedures and control locks
> that absolutely prevent this.
>
> My $0.02.
>
> -Evan Ludeman (15m guy)

Evan,

I did not mean to imply that pulling back on the stick was the
solution to the problem. Note I used the word "might". I agree with
you that at a relitively slow speed, and neg flaps, that there would
not be enough up elevator authority to completely arrest the high sink
rate. You would reduce the sink but probably not enough.

But, you picked up on the minor point of my post, not the major point
which is the fact that the original post contains the misconception
that the retraction of the flaps caused the glider to "stall", and
that a redeploying the flaps caused a "stall recovery"..........

BTW, landing tail first is not necessarily a bad thing, but landing
tail first with a high sink rate is a bad thing.

I did witness a PIK 20 make a succesful landing with it flaps stuck in
the full neg position...(no spoilers on this model). The approach
speed was relatively fast, but no super fast. The landing took up
quite a bit of runway, but really was uneventful! (this was not a
"sudden" retraction of the flaps however).


Cookie

[T8]

On Jan 31, 7:23*am, "
> wrote:
> On Jan 30, 11:35*am, T8 > wrote:
>
>
>
> > On Jan 30, 8:36*am, "
>
> > > wrote:
> > > The pilot could have also pulled back on the stick, which might have
> > > restored the balance of lift, drag, and weight, and arrested the high
> > > sink rate. *
>
> > No way. *He'd have gone in (very) hard on the tail.
>
> > It's probably possible to land a 15m glider in negative flap, but
> > you'd need a final approach speed of *70 kts to do it. *From the
> > description of this incident, it sounds like the pilot was closer to
> > 50 kts and certainly under 55.
>
> > You need to keep in mind that flaps change wing incidence, tail
> > incidence (relative to wing), and especially max CL. *All at once.
> > This pilot made two mistakes (flaps not locked, too slow too high -
> > accident would not have happened if he hadn't had to close the
> > spoilers!) and a very clutch response that saved his ass.
>
> > Uncommanded flap changes in close proximity to the ground or other
> > aircraft are life threatening. *You need procedures and control locks
> > that absolutely prevent this.
>
> > My $0.02.
>
> > -Evan Ludeman (15m guy)
>
> Evan,
>
> I did not mean to imply that pulling back on the stick was the
> solution to the problem. *Note I used the word "might". *I agree with
> you that at a relitively slow speed, and neg flaps, that there would
> not be enough up elevator authority to completely arrest the high sink
> rate. *You would reduce the sink but probably not enough.
>
> But, you picked up on the minor point of my post, not the major point
> which is the fact that the original post contains the misconception
> that the retraction of the flaps caused the glider to "stall", and
> that a redeploying the flaps caused a "stall recovery"..........
>
> BTW, landing tail first is not necessarily a bad thing, but landing
> tail first with a high sink rate is a bad thing.
>
> I did witness a PIK 20 make a succesful landing with it flaps stuck in
> the full neg position...(no spoilers on this model). *The approach
> speed was relatively fast, but no super fast. *The landing took up
> quite a bit of runway, but really was uneventful! *(this was not a
> "sudden" retraction of the flaps however).
>
> Cookie

I agree on tail first landings -- that's my norm on grass -- and that
the LS-6 didn't stall. My point was that the -6 pilot didn't have
enough airspeed to flare in neg. flap.

Some numbers: max Cl for the 62-K131

[T8]

On Jan 31, 7:23*am, "
> wrote:
> On Jan 30, 11:35*am, T8 > wrote:
>
>
>
> > On Jan 30, 8:36*am, "
>
> > > wrote:
> > > The pilot could have also pulled back on the stick, which might have
> > > restored the balance of lift, drag, and weight, and arrested the high
> > > sink rate. *
>
> > No way. *He'd have gone in (very) hard on the tail.
>
> > It's probably possible to land a 15m glider in negative flap, but
> > you'd need a final approach speed of *70 kts to do it. *From the
> > description of this incident, it sounds like the pilot was closer to
> > 50 kts and certainly under 55.
>
> > You need to keep in mind that flaps change wing incidence, tail
> > incidence (relative to wing), and especially max CL. *All at once.
> > This pilot made two mistakes (flaps not locked, too slow too high -
> > accident would not have happened if he hadn't had to close the
> > spoilers!) and a very clutch response that saved his ass.
>
> > Uncommanded flap changes in close proximity to the ground or other
> > aircraft are life threatening. *You need procedures and control locks
> > that absolutely prevent this.
>
> > My $0.02.
>
> > -Evan Ludeman (15m guy)
>
> Evan,
>
> I did not mean to imply that pulling back on the stick was the
> solution to the problem. *Note I used the word "might". *I agree with
> you that at a relitively slow speed, and neg flaps, that there would
> not be enough up elevator authority to completely arrest the high sink
> rate. *You would reduce the sink but probably not enough.
>
> But, you picked up on the minor point of my post, not the major point
> which is the fact that the original post contains the misconception
> that the retraction of the flaps caused the glider to "stall", and
> that a redeploying the flaps caused a "stall recovery"..........
>
> BTW, landing tail first is not necessarily a bad thing, but landing
> tail first with a high sink rate is a bad thing.
>
> I did witness a PIK 20 make a succesful landing with it flaps stuck in
> the full neg position...(no spoilers on this model). *The approach
> speed was relatively fast, but no super fast. *The landing took up
> quite a bit of runway, but really was uneventful! *(this was not a
> "sudden" retraction of the flaps however).
>
> Cookie

I agree that the LS-6 didn't stall. I like tail first landings also.

My point was that the -6 was likely slow enough that it simply
couldn't fly in negative flap and certainly couldn't flare. Looking
up some old charts and extrapolating a bit, I can guesstimate that a
reasonable Cl max with flaps down would be 1.3 - 1.4 and perhaps as
much as 0.9 with flaps negative (by extrapolation -- the chart doesn't
go there because it's not normally of interest!). That's a big
difference. Means -- roughly -- that the minimum flying speed with
flaps up is 22% higher than with flaps down. If you are somewhere in
that speed range and the flaps retract, you sink, regardless of what
you do with the stick. That's consistent with what th LS-6 pilot
reported. A stabilized approach in negative flap is obviously
different - you approach faster because you must to keep flying.

Now if I take my 22% number -- for whatever good that might be -- and
adjust a 52 kt approach speed I get 63 knots. Fair enough. That
makes sense with your observation of the PIK, fast, but not blazingly
so. 70 may be overkill.

regards,
Evan Ludeman / T8

[[email protected]]

On Jan 31, 12:14*pm, T8 > wrote:
> On Jan 31, 7:23*am, "
>
>
>
>
>
> > wrote:
> > On Jan 30, 11:35*am, T8 > wrote:
>
> > > On Jan 30, 8:36*am, "
>
> > > > wrote:
> > > > The pilot could have also pulled back on the stick, which might have
> > > > restored the balance of lift, drag, and weight, and arrested the high
> > > > sink rate. *
>
> > > No way. *He'd have gone in (very) hard on the tail.
>
> > > It's probably possible to land a 15m glider in negative flap, but
> > > you'd need a final approach speed of *70 kts to do it. *From the
> > > description of this incident, it sounds like the pilot was closer to
> > > 50 kts and certainly under 55.
>
> > > You need to keep in mind that flaps change wing incidence, tail
> > > incidence (relative to wing), and especially max CL. *All at once.
> > > This pilot made two mistakes (flaps not locked, too slow too high -
> > > accident would not have happened if he hadn't had to close the
> > > spoilers!) and a very clutch response that saved his ass.
>
> > > Uncommanded flap changes in close proximity to the ground or other
> > > aircraft are life threatening. *You need procedures and control locks
> > > that absolutely prevent this.
>
> > > My $0.02.
>
> > > -Evan Ludeman (15m guy)
>
> > Evan,
>
> > I did not mean to imply that pulling back on the stick was the
> > solution to the problem. *Note I used the word "might". *I agree with
> > you that at a relitively slow speed, and neg flaps, that there would
> > not be enough up elevator authority to completely arrest the high sink
> > rate. *You would reduce the sink but probably not enough.
>
> > But, you picked up on the minor point of my post, not the major point
> > which is the fact that the original post contains the misconception
> > that the retraction of the flaps caused the glider to "stall", and
> > that a redeploying the flaps caused a "stall recovery"..........
>
> > BTW, landing tail first is not necessarily a bad thing, but landing
> > tail first with a high sink rate is a bad thing.
>
> > I did witness a PIK 20 make a succesful landing with it flaps stuck in
> > the full neg position...(no spoilers on this model). *The approach
> > speed was relatively fast, but no super fast. *The landing took up
> > quite a bit of runway, but really was uneventful! *(this was not a
> > "sudden" retraction of the flaps however).
>
> > Cookie
>
> I agree that the LS-6 didn't stall. *I like tail first landings also.
>
> My point was that the -6 was likely slow enough that it simply
> couldn't fly in negative flap and certainly couldn't flare. *Looking
> up some old charts and extrapolating a bit, I can guesstimate that a
> reasonable Cl max with flaps down would be 1.3 - 1.4 and perhaps as
> much as 0.9 with flaps negative (by extrapolation -- the chart doesn't
> go there because it's not normally of interest!). *That's a big
> difference. *Means -- roughly -- that the minimum flying speed with
> flaps up is 22% higher than with flaps down. *If you are somewhere in
> that speed range and the flaps retract, you sink, regardless of what
> you do with the stick. *That's consistent with what th LS-6 pilot
> reported. *A stabilized approach in negative flap is obviously
> different - you approach faster because you must to keep flying.
>
> Now if I take my 22% number -- for whatever good that might be -- and
> adjust a 52 kt approach speed I get 63 knots. *Fair enough. *That
> makes sense with your observation of the PIK, fast, but not blazingly
> so. *70 may be overkill.
>
> regards,
> Evan Ludeman / T8- Hide quoted text -
>
> - Show quoted text -


OK.....I'm with you now. Back to the original post and original
problem......it's like the guy who goes to the doctor and says, "Doc
it hurts when I do this." So the doc says, "Don't do that!"

"My LS-6 crashes when I retract the flaps at low
altitude"......."Don't retract the flaps at low altitude!"


Cookie