Elevator Turbulator tape question

Kirk Stant wrote

ITS MY LIFE AND I CAN DO WHAT I WANT WITH IT, THANK
YOU
VERY MUCH!

Kirk (last bastion of stupid individualism)
66


I would defend to the end your right to do what you
want with your life.

Sadly it is not those who kill themselves that is the
problem, it is

The 'friends' left behind who have to scrape the bits
of the airfield and shovel them into a body bag. (Yes
I have done it)

The relatives who have to be comforted. (And this)

Followed by the thieving grasping lawyers who make
a fortune out of the grief left behind. (and seen
this happen)

So come on take care have a thought for the others
you will leave behind and make sure the lawyers have
to live of state benefits and our premiums stay low.

If you want to kill yourself go out quietly and shoot
yourself please do so. It is also easier and cheaper.

Please!

(John) wrote in message . com...
My '6 came with turbulator tape on the bottom surface, just in front
of the elevator. 1994 C model. The stall is very gentle.


J4


That's interesting. Does your aircraft or maintenance manual have any
info on the tail tape (placement, size, etc.)? My 6 is an 87 B model,
no tape anywhere except on the rudder mylar (zigzag leading edge).

I have a hard time figuring out how increasing elevator effectiveness
would make a stall "harder", since the wing should stall at the same
angle of attack and with the same flow pattern; you may be able to get
deeper into the stall with full aft stick (maybe better spin entry)
but that should be about it.
Right now the 6's stall is so gentle as to be almost nonexistent, I
can only really get any kind of break with landing flaps, in
thermalling flap it just nods a little.

I'll check with LS/DG and see what they say about it.

Meanwhile, the rest of you guys out there relax, I appreciate your
concern but I haven't reached this ripe almost old age by doing really
stupid things. Mildly stupid things, perhaps (like paying too much
attention to RAS).

Kirk
66

Kirk Stant wrote

Meanwhile, the rest of you guys out there relax, I
appreciate your concern but I haven't reached this
ripe almost old age by doing really stupid things.
Mildly stupid things, perhaps (like paying too much
attention to RAS).

Kirk
66

Point taken!

Half the trouble is most gliding clubs have a box at
the gate where many members leave their brains, spend
a day on the airfield and then collect the brain on
the way home.

Sorting out .......those who know what they are doing
from
.... those who think they know what they are doing
from
.....those who know absolutely nothing but go on and
do it anyway from....... those who can't do it but
have seen somebody else do it so they will try it anyway


All goes to provides a headache for the fun police,
who can't do right for doing wrong....!

Hope the turbulator tape works.

Dave

in article , Dave Martin at
wrote on 2003/10/11 4:41:


I would defend to the end your right to do what you
want with your life.

Sadly it is not those who kill themselves that is the
problem, it is

The 'friends' left behind....

The relatives....

...the thieving grasping lawyers....

[H]ave a thought for the others....

If you want to kill yourself go out quietly and shoot
yourself....

Which would, of course, solve _none_ of the so-called "problems" you listed
above.

You would "defend to the death" my right to -- what? Live so that you and
others are never inconvienienced?

I know we can't expect your ilk to understand that it is that kind of
thinking that has got the world where it is today, but a little less
hypocrisy would be nice.




Jack

Earlier, (John) wrote:

My '6 came with turbulator tape on the bottom surface, just in front
of the elevator. 1994 C model. The stall is very gentle.

To which (Kirk Stant) replied:

That's interesting. Does your aircraft or maintenance manual have any
info on the tail tape (placement, size, etc.)? My 6 is an 87 B model,
no tape anywhere except on the rudder mylar (zigzag leading edge).

I've heard unconfirmed reports that the later model LS6s have a
revised tailplane with a thinner section. Again, that's just hearsay,
but it might be something to look into. Can anyone here confirm or
deny?

Thanks, and best regards to all

Bob K.

Kirk,
I agree with you that competent, current pilots, don't inadvertently stall any
ship. But your statement that you like a crisp stall, got me wondering. How do
you like a crisp stall, in the pattern, after some hard maneuvering to avoid a
mid-air? How do you like a crisp stall, when on the rocks, and get hit with a
large tail-gust?

The stall I got in my LS-7, after adding zig-zag to the horizontal stab, was
the worst stall I have ever seen in any sailplane. I mean she went near
vertical on me. Don't care to duplicate that in the above situations.

PS, I suspect the zig-zag delayed the *normal* seperation on the stab, but when
it did seperate, I lost all the down force from the horizontal stab and that
gave me the near vertical pitching moment. The wing may not have stalled at
all. Now someone please feel free to tell me just how full of Ka-ka, I am about
aerodynamics.
:)
JJ Sinclair

JJ, you are about right on. I strongly suspect that if a glider "stalls"
but retains aileron control, the wing didn't really stall - just the
horizontal tail lost its grip on the air and let the tail pop up (Nose pops
down). Normally, this is a pretty benign way to limit minimum airspeed.
Adding any device to increase up elevator authority might allow the pilot
bring the whole wing to stall with the possibility of a spin departure.

It seems to me that the only reason to increase up elevator authority would
be to improve thermaling and then only in the case of a glider whose minimum
airspeed is limited by up elevator ineffectiveness. A case might be the
G103 Twin II when the CG is near the forward limit. This limits minimum
airspeed to well above minimum sink in a steep turn.

Bill Daniels

"JJ Sinclair" wrote in message
...
Kirk,
I agree with you that competent, current pilots, don't inadvertently stall
any
ship. But your statement that you like a crisp stall, got me wondering.
How do
you like a crisp stall, in the pattern, after some hard maneuvering to
avoid a
mid-air? How do you like a crisp stall, when on the rocks, and get hit
with a
large tail-gust?

The stall I got in my LS-7, after adding zig-zag to the horizontal stab,
was
the worst stall I have ever seen in any sailplane. I mean she went near
vertical on me. Don't care to duplicate that in the above situations.

PS, I suspect the zig-zag delayed the *normal* seperation on the stab, but
when
it did seperate, I lost all the down force from the horizontal stab and
that
gave me the near vertical pitching moment. The wing may not have stalled
at
all. Now someone please feel free to tell me just how full of Ka-ka, I am
about
aerodynamics.
:)
JJ Sinclair

(JJ Sinclair) wrote in message ...
Kirk,
I agree with you that competent, current pilots, don't inadvertently stall any
ship. But your statement that you like a crisp stall, got me wondering. How do
you like a crisp stall, in the pattern, after some hard maneuvering to avoid a
mid-air? How do you like a crisp stall, when on the rocks, and get hit with a
large tail-gust?

The stall I got in my LS-7, after adding zig-zag to the horizontal stab, was
the worst stall I have ever seen in any sailplane. I mean she went near
vertical on me. Don't care to duplicate that in the above situations.

PS, I suspect the zig-zag delayed the *normal* seperation on the stab, but when
it did seperate, I lost all the down force from the horizontal stab and that
gave me the near vertical pitching moment. The wing may not have stalled at
all. Now someone please feel free to tell me just how full of Ka-ka, I am about
aerodynamics.
:)
JJ Sinclair


JJ,

I like planes that have enough control authority to stall, not those
limited to just mushing along at a high sink rate. I absolutely do
not believe that it is safer to have a high sink rate while turning
base to final because all the stall symptoms are hidden - a stall
break will provide the cue to unload and recover. Anyway, the whole
point is to not stall unless you want to, whether you are mushing
along with the stick full aft, or recovering from a g-break; either
way for a while there you are a passenger - and as a pilot you
shouldn't get in that situation. And yes, I do practice stalls, and
fly fast steep patterns, and believe in spin training, and practice
getting slow in a steep thermalling turn, etc. I guess the difference
is I like control of the plane in pitch all the way into and back out
of a stall. Might be due to liking acro...and mildly disliking mushy
POS's like 2-33s, etc. On the other hand, I do like ASK-21s, and they
will not stall at normal CGs (except inverted, of course...). So
there are always exceptions.

If turbulator tape resulted in your tail stalling, that is a different
matter altogether. I have a hard time understanding it, especially
since other similar configuration glass have turbulated tails - but if
I go ahead and try it I will definitely check it out. So thanks for
the heads up!

Of course, there is a lot of difference between a 6 and a 7, so who
knows what will happen!

Kirk

I'm not aware of any glider that stalls from a sharp
break stall on the horizontal stab, though many of
us have experienced running out of elevator authority
- just try any combination of pushing the c.g. forward
or increasing the bank angle in a turn to make this
real (I have, and it's annoying in a thermal, though
not particularly dangerous unless taken to extremes).

Turbulator tape trips the boundary layer from laminar
to turbulent and should allow the elevator to create
lift at higher, rathern than lower angles of attack,
so unless you change the wing or tail incidence it's
hard to imagine that it would lead to the tail stalling
first. What likely happens is it gives you enough
additional authority to get the wing to really stall,
rather than mush around just past max Cl angle of attack.


I won't say whether this is good or bad per se.

9B

At 20:30 14 October 2003, Bill Daniels wrote:
JJ, you are about right on. I strongly suspect that
if a glider 'stalls'
but retains aileron control, the wing didn't really
stall - just the
horizontal tail lost its grip on the air and let the
tail pop up (Nose pops
down). Normally, this is a pretty benign way to limit
minimum airspeed.
Adding any device to increase up elevator authority
might allow the pilot
bring the whole wing to stall with the possibility
of a spin departure.

It seems to me that the only reason to increase up
elevator authority would
be to improve thermaling and then only in the case
of a glider whose minimum
airspeed is limited by up elevator ineffectiveness.
A case might be the
G103 Twin II when the CG is near the forward limit.
This limits minimum
airspeed to well above minimum sink in a steep turn.

Bill Daniels

'JJ Sinclair' wrote in message
...
Kirk,
I agree with you that competent, current pilots, don't
inadvertently stall
any
ship. But your statement that you like a crisp stall,
got me wondering.
How do
you like a crisp stall, in the pattern, after some
hard maneuvering to
avoid a
mid-air? How do you like a crisp stall, when on the
rocks, and get hit
with a
large tail-gust?

The stall I got in my LS-7, after adding zig-zag to
the horizontal stab,
was
the worst stall I have ever seen in any sailplane.
I mean she went near
vertical on me. Don't care to duplicate that in the
above situations.

PS, I suspect the zig-zag delayed the *normal* seperation
on the stab, but
when
it did seperate, I lost all the down force from the
horizontal stab and
that
gave me the near vertical pitching moment. The wing
may not have stalled
at
all. Now someone please feel free to tell me just
how full of Ka-ka, I am
about
aerodynamics.
:)
JJ Sinclair

JJ Sinclair wrote:

Kirk,
I agree with you that competent, current pilots, don't inadvertently stall any
ship. But your statement that you like a crisp stall, got me wondering. How do
you like a crisp stall, in the pattern, after some hard maneuvering to avoid a
mid-air? How do you like a crisp stall, when on the rocks, and get hit with a
large tail-gust?

The stall I got in my LS-7, after adding zig-zag to the horizontal stab, was
the worst stall I have ever seen in any sailplane. I mean she went near
vertical on me. Don't care to duplicate that in the above situations.

PS, I suspect the zig-zag delayed the *normal* seperation on the stab, but when
it did seperate, I lost all the down force from the horizontal stab and that
gave me the near vertical pitching moment. The wing may not have stalled at
all. Now someone please feel free to tell me just how full of Ka-ka, I am about
aerodynamics.
:)
JJ Sinclair

I am not an expert in aerodynamics, but I don't agree with your above interpretation.
It implies that just below the stall your elevator was producing a down force,
near the maximum possible or rather the (negative) lift coefficient was near its maximum
possible value and this maximum value was reached when you lost control, before
the wing reached its maximum (positive) lift coefficient. It seems to me that it
is an error to believe that more down force on the tail plane is needed for obtaining
an higher nose up attitude. As airfoils commonly used in sailplanes are unstable,
more nose up attitudes tend to self amplify when you consider only the forces
on the wing and the tail plane has to counter this by a lower down force (or a higher
up force, depending on position of the CG). This is not in contradiction with the
fact that you need aft stick in order to keep a higher nose up attitude.
This change of attitude also change the angle of attack on the tail plane by an
amount exceeding the variation of force needed and the back stick has to compensate for this.
For these reasons I think that when you come closer to the stalling angle of attack
for the wing, the tailplane on the contrary is far from its stalling angle of attack.
When the wing reaches its stalling angle, a further increase in angle of attack
will lower the lift coefficient, thus increasing again the angle of attack due
to the glider beginning to fall and so on. This also increases the angle of attack on the
tailplane which produces an upward force, despite the full aft stick, and this
produces the pitching moment that makes the nose drop. It would be logic to think
that in this case, the increased efficiency of the the tail plane due to the added
turbulator increases the pitching moment and brings the glider more quickly
closer to a vertical dive.