TE probe up or down?

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

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"

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...n_20020510.pdf

John Galloway

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...n_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

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! 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

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

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

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

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

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


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