TE probe up or down?

[kirk.stant]

It's raining at the field today so here is a serious soaring question
to ponder:

Should the end of the TE probe on the fin point up or down?

Informal surveys at recent contests seem to show a slight preference
for up (not counting those "swingers" that go both ways).

I've heard all sorts of reasons why each orientation is best - angle
of attack during pull-ups, airflow in front of the tail, G-effects on
the air column, blah blah blah...

I point mine up so I don't snag it when taking off the tail dolly!

Comments?

Kirk
Wet in IL

[Dave Nadler]

On Sep 26, 3:13*pm, "kirk.stant" > wrote:
> It's raining at the field today so here is a serious soaring question
> to ponder:
>
> Should the end of the TE probe on the fin point up or down?
>
> Informal surveys at recent contests seem to show a slight preference
> for up (not counting those "swingers" that go both ways).
>
> I've heard all sorts of reasons why each orientation is best - angle
> of attack during pull-ups, airflow in front of the tail, G-effects on
> the air column, blah blah blah...
>
> I point mine up so I don't snag it when taking off the tail dolly!
>
> Comments?
>
> Kirk
> Wet in IL

Up. as far awat from effects of the wing (and tail) as possible.
Except on some sailplanes where down works better.

See ya, Dave "YO electric"

[johngalloway[_2_]]

On 26 Sep, 20:13, "kirk.stant" > wrote:
> It's raining at the field today so here is a serious soaring question
> to ponder:
>
> Should the end of the TE probe on the fin point up or down?
>
> Informal surveys at recent contests seem to show a slight preference
> for up (not counting those "swingers" that go both ways).
>
> I've heard all sorts of reasons why each orientation is best - angle
> of attack during pull-ups, airflow in front of the tail, G-effects on
> the air column, blah blah blah...
>
> I point mine up so I don't snag it when taking off the tail dolly!
>
> Comments?
>
> Kirk
> Wet in IL

From Rudy Brozel's classic article on total energy:

"The head of the probe should be as close as possible to the plane of
symmetry of the horizontal tail plane. The smaller the vertical
offset, the less the elevator affects the variometer. A vertical
distance over half the depth of the horizontal tail plane is very
bad!"

http://www.nadler.com/sn10/Brozel_TE_Compensation_20020510.pdf

John Galloway

[Brad[_2_]]

On Sep 26, 12:57*pm, johngalloway > wrote:
> On 26 Sep, 20:13, "kirk.stant" > wrote:
>
>
>
>
>
> > It's raining at the field today so here is a serious soaring question
> > to ponder:
>
> > Should the end of the TE probe on the fin point up or down?
>
> > Informal surveys at recent contests seem to show a slight preference
> > for up (not counting those "swingers" that go both ways).
>
> > I've heard all sorts of reasons why each orientation is best - angle
> > of attack during pull-ups, airflow in front of the tail, G-effects on
> > the air column, blah blah blah...
>
> > I point mine up so I don't snag it when taking off the tail dolly!
>
> > Comments?
>
> > Kirk
> > Wet in IL
>
> From Rudy Brozel's classic article on total energy:
>
> "The head of the probe should be as close as possible to the plane of
> symmetry of the horizontal tail plane. The smaller the vertical
> offset, the less the elevator affects the variometer. A vertical
> distance over half the depth of the horizontal tail plane is very
> bad!"
>
> http://www.nadler.com/sn10/Brozel_TE_Compensation_20020510.pdf
>
> John Galloway

if I have mine up (which I prefer) it gets close to the plane the
pitot tube is in..................would that possible disrupt the flow
for the pitot?

Brad

[sisu1a]

> I point mine up so I don't snag it when taking off the tail dolly!

I thought it best to point it whichever direction will keep it as
perpendicular to the airstream it's reading from for as much of the
flight regime as possible, in an attempt to keep the flow within
+/-20deg to keep the probe from reading erroneously.

Mine points down, and is really short too! :o I have a cruciform
tail though, so I don't get probe envy since it's well clear of the
bow wake of the tailplane. In fact I prefer it this way and well...
at least my vario tells me size doesn't matter ;)

-Paul

[Andy[_1_]]

On Sep 26, 12:13*pm, "kirk.stant" > wrote:
> It's raining at the field today so here is a serious soaring question
> to ponder:

Why be so limited in your thinking? What's wrong with sideways?
Then you can ponder which of those 2 options depending on you
thermalling direction preference.

I point mine up so I'm less likely to bend it.


Andy

[glidergeek]

On Sep 26, 12:13*pm, "kirk.stant" > wrote:
> It's raining at the field today so here is a serious soaring question
> to ponder:
>
> Should the end of the TE probe on the fin point up or down?
>
> Informal surveys at recent contests seem to show a slight preference
> for up (not counting those "swingers" that go both ways).
>
> I've heard all sorts of reasons why each orientation is best - angle
> of attack during pull-ups, airflow in front of the tail, G-effects on
> the air column, blah blah blah...
>
> I point mine up so I don't snag it when taking off the tail dolly!
>
> Comments?
>
> Kirk
> Wet in IL

DOWN

[John Smith]

To state the obvious: Male pilots prefer up.

[Wayne Paul]

When I had a TE probe installed on my Ka-6E I ask Roger Frank the posting subject question. He responded immediately "it should be UP!! Otherwise some jerk will hang their hat on it."

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



"kirk.stant" > wrote in message ...
> It's raining at the field today so here is a serious soaring question
> to ponder:
>
> Should the end of the TE probe on the fin point up or down?
>
> Informal surveys at recent contests seem to show a slight preference
> for up (not counting those "swingers" that go both ways).
>
> I've heard all sorts of reasons why each orientation is best - angle
> of attack during pull-ups, airflow in front of the tail, G-effects on
> the air column, blah blah blah...
>
> I point mine up so I don't snag it when taking off the tail dolly!
>
> Comments?
>
> Kirk
> Wet in IL

[Wayne Paul]

Opps, I ment to type "it should be DOWN!! Otherwise some jerk will hang their had on it."

"Wayne Paul" > wrote in message ...
When I had a TE probe installed on my Ka-6E I ask Roger Frank the posting subject question. He responded immediately "it should be UP!! Otherwise some jerk will hang their hat on it."

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



"kirk.stant" > wrote in message ...
> It's raining at the field today so here is a serious soaring question
> to ponder:
>
> Should the end of the TE probe on the fin point up or down?
>
> Informal surveys at recent contests seem to show a slight preference
> for up (not counting those "swingers" that go both ways).
>
> I've heard all sorts of reasons why each orientation is best - angle
> of attack during pull-ups, airflow in front of the tail, G-effects on
> the air column, blah blah blah...
>
> I point mine up so I don't snag it when taking off the tail dolly!
>
> Comments?
>
> Kirk
> Wet in IL

[Mike Ash]

In article
>,
Andy > wrote:

> On Sep 26, 12:13*pm, "kirk.stant" > wrote:
> > It's raining at the field today so here is a serious soaring question
> > to ponder:
>
> Why be so limited in your thinking? What's wrong with sideways?
> Then you can ponder which of those 2 options depending on you
> thermalling direction preference.
>
> I point mine up so I'm less likely to bend it.

Ironic how you accuse Kirk of limited thinking and yet you yourself use
a technique which gives you a mere four total options.

When the time comes to insert my TE probe, I get out my iPhone and have
it generate a random number in the range [0, 2pi). I then orient my TE
probe to the angle that this represents in radians. In this manner I
eliminate human bias and therefore increase thermalling performance.

--
Mike Ash
Radio Free Earth
Broadcasting from our climate-controlled studios deep inside the Moon

[SoaringXCellence]

Ah Ha! the new indicator of a worthless thread, Someone mentions an
iPhone app.

[[email protected]]

On Sep 26, 3:13*pm, "kirk.stant" > wrote:
> It's raining at the field today so here is a serious soaring question
> to ponder:
>
> Should the end of the TE probe on the fin point up or down?
>
> Informal surveys at recent contests seem to show a slight preference
> for up (not counting those "swingers" that go both ways).
>
> I've heard all sorts of reasons why each orientation is best - angle
> of attack during pull-ups, airflow in front of the tail, G-effects on
> the air column, blah blah blah...
>
> I point mine up so I don't snag it when taking off the tail dolly!
>
> Comments?
>
> Kirk
> Wet in IL

Up works better for me on Schleicher gliders. This raises the sensing
point about 6 inches which reduces errors form wing root vortexes
whien I pull really hard.
I leave probe in cockpit on claf pad until glider is on the grid with
dolly off to avoid damage.
FWIW
UH

[Tim Mara]

Pete Russel (former SAGE Variometer maker) tested TE probes in all
directions..Pete reported it worked equally as well off to the left or right
as it did up or down....
if you can't decide, ESA has made for several years their DN/ST probes that
have both up and down ends.....all users have reported that these work
really very well...
see http://www.wingsandwheels.com/page20.htm
tim

"Andy" > wrote in message
...
On Sep 26, 12:13 pm, "kirk.stant" > wrote:
> It's raining at the field today so here is a serious soaring question
> to ponder:

Why be so limited in your thinking? What's wrong with sideways?
Then you can ponder which of those 2 options depending on you
thermalling direction preference.

I point mine up so I'm less likely to bend it.


Andy


__________ Information from ESET NOD32 Antivirus, version of virus signature
database 5483 (20100927) __________

The message was checked by ESET NOD32 Antivirus.

http://www.eset.com





__________ Information from ESET NOD32 Antivirus, version of virus signature database 5483 (20100927) __________

The message was checked by ESET NOD32 Antivirus.

http://www.eset.com

[Mike Ash]

In article
>,
SoaringXCellence > wrote:

> Ah Ha! the new indicator of a worthless thread, Someone mentions an
> iPhone app.

It was the iPhone mention that bothers you, and not the claim that a
randomly-chosen angle improves thermalling performance by removing human
bias?

--
Mike Ash
Radio Free Earth
Broadcasting from our climate-controlled studios deep inside the Moon

[Grider Pirate]

On Sep 26, 12:13*pm, "kirk.stant" > wrote:
> It's raining at the field today so here is a serious soaring question
> to ponder:
>
> Should the end of the TE probe on the fin point up or down?
>
> Informal surveys at recent contests seem to show a slight preference
> for up (not counting those "swingers" that go both ways).
>
> I've heard all sorts of reasons why each orientation is best - angle
> of attack during pull-ups, airflow in front of the tail, G-effects on
> the air column, blah blah blah...
>
> I point mine up so I don't snag it when taking off the tail dolly!
>
> Comments?
>
> Kirk
> Wet in IL

I point mine down. I tried it pointed up once, because all the cool
kids were doing it. I found that with it pointed up, the onset of
'needle flutter' happened sooner on my glider. Also, if I tie out for
a day, and it rains, there is a possiblilty of water getting into my
system with it pointed up.

[Whiskey Delta]

On Sep 27, 1:44*pm, Grider Pirate > wrote:
> On Sep 26, 12:13*pm, "kirk.stant" > wrote:
>
>
> I point mine down. *I tried it pointed up once, because all the cool
> kids were doing it. *I found that with it pointed up, the onset of
> 'needle flutter' happened sooner on my glider. *Also, if I tie out for
> a day, and it rains, there is a possiblilty of water getting into my
> system with it pointed up.


Put a bag over it and you can keep it pointed up....

[vontresc]

On Sep 27, 12:49*pm, Whiskey Delta > wrote:
> On Sep 27, 1:44*pm, Grider Pirate > wrote:
>
> > On Sep 26, 12:13*pm, "kirk.stant" > wrote:
>
> > I point mine down. *I tried it pointed up once, because all the cool
> > kids were doing it. *I found that with it pointed up, the onset of
> > 'needle flutter' happened sooner on my glider. *Also, if I tie out for
> > a day, and it rains, there is a possiblilty of water getting into my
> > system with it pointed up.
>
> Put a bag over it and you can keep it pointed up....

After day two of the Memorial Day contest in Huntley this year, we had
the regular hangar BS session in the evening. Herb Killian was of the
opinion that it should point down. It did have something to do with a
pee bag snagging on the upturned TE probe :-)

Pete

[drbdanieli]

According to the ESA website, which adressed this frequently ask
question, it should be pointed up according to professor Loek
Boermans unless you have the DN/x type probe. This probe should be
mounted horizontally, i.e. parallel to the wings. They also explain
the reasoning for this.

Barry

[Rolf[_2_]]

On Sep 27, 5:13*am, "kirk.stant" > wrote:
> It's raining at the field today so here is a serious soaring question
> to ponder:
>
> Should the end of the TE probe on the fin point up or down?
>
> Informal surveys at recent contests seem to show a slight preference
> for up (not counting those "swingers" that go both ways).
>
> I've heard all sorts of reasons why each orientation is best - angle
> of attack during pull-ups, airflow in front of the tail, G-effects on
> the air column, blah blah blah...
>
> I point mine up so I don't snag it when taking off the tail dolly!
>
> Comments?
>
> Kirk
> Wet in IL

Well, your very own Oran W. Nicks describes the development of the
probe in your "Soaring" magazine of September 1976. He definitely has
the probe pointing up. As he is the inventor and arrived at the
configuration in extensive wind tunnel tests that settles it for me.

Rolf

[Dave Nadler]

On Sep 27, 11:46*am, "Tim Mara" > wrote:
> Pete Russel (former SAGE Variometer maker) tested TE probes in all
> directions..Pete reported it worked equally as well off to the left or right
> as it did up or down....

Its completely dependent on the glider and the length of the probe...
In general, UP is much preferred.

See ya, Dave

[HL Falbaum[_2_]]

"Rolf" > wrote in message
...
On Sep 27, 5:13 am, "kirk.stant" > wrote:
> It's raining at the field today so here is a serious soaring question
> to ponder:
>
> Should the end of the TE probe on the fin point up or down?
>
> Informal surveys at recent contests seem to show a slight preference
> for up (not counting those "swingers" that go both ways).
>
> I've heard all sorts of reasons why each orientation is best - angle
> of attack during pull-ups, airflow in front of the tail, G-effects on
> the air column, blah blah blah...
>
> I point mine up so I don't snag it when taking off the tail dolly!
>
> Comments?
>
> Kirk
> Wet in IL

>Well, your very own Oran W. Nicks describes the development of the
>probe in your "Soaring" magazine of September 1976. He definitely has
>the probe pointing up. As he is the inventor and arrived at the
>configuration in extensive wind tunnel tests that settles it for me.

>Rolf

And Professor Irving, who developed two different designs, shows his pointed
down, and 20 degrees forward. Professor Irving also used wind tunnel
testing. So there!


Hartley Falbaum
"KF" USA

[Chris Nicholas[_2_]]

This is pure speculation, but I wonder if Prof Frank Irving’s
preference for the probe pointing downwards is because in his day, and
particularly in the UK, cloud flying was commonplace.

It follows that accumulation of water droplets on the probe was also,
common. After only a few minutes in cloud, it is usual to find that
the vario starts misbehaving. (I find that typically, it suddenly
stops displaying rate of climb accurately, and then flicks to a
different reading, then settles back to something sensible for a few
seconds, and then repeats the cycle. I put this down to water droplets
accumulating, to the point that they block the tiny holes in the
probe, then suddenly get freed, then repeat the cycle. I have no means
of knowing whether my speculation in this respect is accurate.)

Anything that can delay that, or at least get rid of surplus water
droplets so that the vario returns to functionality for a few seconds
at a time, is probably worth doing.

If you're not flying where water droplets are likely to accumulate on
the probe, other things being equal it seems to me that keeping it as
far from disturbed air over the wings as possible is a good thing,
hence up.

Just my two cents worth.

Chris N

[Derek C]

On Sep 28, 10:45*am, Chris Nicholas > wrote:
> This is pure speculation, but I wonder if Prof Frank Irving’s
> preference for the probe pointing downwards is because in his day, and
> particularly in the UK, cloud flying was commonplace.
>
> It follows that accumulation of water droplets on the probe was also,
> common. *After only a few minutes in cloud, it is usual to find that
> the vario starts misbehaving. (I find that typically, it suddenly
> stops displaying rate of climb accurately, and then flicks to a
> different reading, then settles back to something sensible for a few
> seconds, and then repeats the cycle. I put this down to water droplets
> accumulating, to the point that they block the tiny holes in the
> probe, then suddenly get freed, then repeat the cycle. I have no means
> of knowing whether my speculation in this respect is accurate.)
>
> *Anything that can delay that, or at least get rid of surplus water
> droplets so that the vario returns to functionality for a few seconds
> at a time, is probably worth doing.
>
> If you're not flying where water droplets are likely to accumulate on
> the probe, other things being equal it seems to me that keeping it as
> far from disturbed air over the wings as possible is a good thing,
> hence up.
>
> Just my two cents worth.
>
> Chris N

Gliders with short rear fuselage mounted TE probes often suffer from a
flickering and false vario reading when flown at high angles of
attack, as in a thermalling turn. I assume that this is because of
interference from turbulent air coming off the wings. I have also
experienced this effect with some fin mounted probes. I would point
the probe upwards to keep it as clear as possible from any wing
turbulence.

Derek C

[Jonathon May[_2_]]

At 14:21 28 September 2010, Derek C wrote:
>On Sep 28, 10:45=A0am, Chris Nicholas wrote:
>> This is pure speculation, but I wonder if Prof Frank Irving=92s
>> preference for the probe pointing downwards is because in his day, and
>> particularly in the UK, cloud flying was commonplace.
>>
>> It follows that accumulation of water droplets on the probe was also,
>> common. =A0After only a few minutes in cloud, it is usual to find that
>> the vario starts misbehaving. (I find that typically, it suddenly
>> stops displaying rate of climb accurately, and then flicks to a
>> different reading, then settles back to something sensible for a few
>> seconds, and then repeats the cycle. I put this down to water droplets
>> accumulating, to the point that they block the tiny holes in the
>> probe, then suddenly get freed, then repeat the cycle. I have no means
>> of knowing whether my speculation in this respect is accurate.)
>>
>> =A0Anything that can delay that, or at least get rid of surplus water
>> droplets so that the vario returns to functionality for a few seconds
>> at a time, is probably worth doing.
>>
>> If you're not flying where water droplets are likely to accumulate on
>> the probe, other things being equal it seems to me that keeping it as
>> far from disturbed air over the wings as possible is a good thing,
>> hence up.
>>
>> Just my two cents worth.
>>
>> Chris N
>
>Gliders with short rear fuselage mounted TE probes often suffer from a
>flickering and false vario reading when flown at high angles of
>attack, as in a thermalling turn. I assume that this is because of
>interference from turbulent air coming off the wings. I have also
>experienced this effect with some fin mounted probes. I would point
>the probe upwards to keep it as clear as possible from any wing
>turbulence.
>
>Derek C
>


We use to use a nose mounted probe on a K18 I flew,not sure how good it
was, but the yaw string mounted on it was much better as it didn't over
react as much.
Jon
>

[Nyal Williams[_2_]]

You probably had the string tied around the holes that make the thing work.
The yarn sucked away the moisture from the holes so that they could
continue to work and that moisture in the yaw string caused it to be
heavier and thus not fluctuate so much. That is good theory!

At 07:42 29 September 2010, Jonathon May wrote:
>At 14:21 28 September 2010, Derek C wrote:
>>On Sep 28, 10:45=A0am, Chris Nicholas wrote:
>>> This is pure speculation, but I wonder if Prof Frank Irving=92s
>>> preference for the probe pointing downwards is because in his day,
and
>>> particularly in the UK, cloud flying was commonplace.
>>>
>>> It follows that accumulation of water droplets on the probe was also,
>>> common. =A0After only a few minutes in cloud, it is usual to find
that
>>> the vario starts misbehaving. (I find that typically, it suddenly
>>> stops displaying rate of climb accurately, and then flicks to a
>>> different reading, then settles back to something sensible for a few
>>> seconds, and then repeats the cycle. I put this down to water
droplets
>>> accumulating, to the point that they block the tiny holes in the
>>> probe, then suddenly get freed, then repeat the cycle. I have no
means
>>> of knowing whether my speculation in this respect is accurate.)
>>>
>>> =A0Anything that can delay that, or at least get rid of surplus water
>>> droplets so that the vario returns to functionality for a few seconds
>>> at a time, is probably worth doing.
>>>
>>> If you're not flying where water droplets are likely to accumulate
on
>>> the probe, other things being equal it seems to me that keeping it as
>>> far from disturbed air over the wings as possible is a good thing,
>>> hence up.
>>>
>>> Just my two cents worth.
>>>
>>> Chris N
>>
>>Gliders with short rear fuselage mounted TE probes often suffer from a
>>flickering and false vario reading when flown at high angles of
>>attack, as in a thermalling turn. I assume that this is because of
>>interference from turbulent air coming off the wings. I have also
>>experienced this effect with some fin mounted probes. I would point
>>the probe upwards to keep it as clear as possible from any wing
>>turbulence.
>>
>>Derek C
>>
>
>
>We use to use a nose mounted probe on a K18 I flew,not sure how good it
>was, but the yaw string mounted on it was much better as it didn't over
>react as much.
>Jon
>>
>
>