I think it would cause significant errors because there
are unavoidable but detectable errors in fin mounted
TE probes from the relative but small downwards motion
of the tail end of the glider as you pull up (in addition
to the g effects). The relative motion would be much
greater between the fuselage and mid span in rolling
than between the fin and centre of rotation in pitching.

The best place for a TE probe that is not on the fin
would be far in front of the nose. In that position
the vertical movement effects would counteract the
g effects.

John Galloway


At 22:30 25 November 2004, Ian Cant wrote:
If the TE probe is mounted at half-span or more, will
any application of bank not cause a correctly-compensated
TE to read climb or descent [because the mounting point
is moving up or down as bank is applied] ? Is this
significant ?

Ian



At 15:31 24 November 2004, Bert Willing wrote:
Sorry if I gave reasons to misinterprete.
TE is based on pressure changes due to changes in speed
(which in turn are
caused by changes of angle of attack). But you can
expect the pressure
change to be significantly different in the vicinity
of the wing, than in a
free flow section, so the TE would not read correctly
for the whole range of
airspeed.

That's the reason why TE's are mounted either above
the middle of the tail
boom, or something like half a meter in front of the
wing.

--
Bert Willing

ASW20 'TW'


'Paul Remde' a écrit dans le message de news:
pT0pd.79775$V41.37553@attbi_s52...
Hi,

Is angle of attack a big part of TE compensation?
I thought it was mainly
pressure changes due to airspeed changes. I'll have
to do some reading on
this. I think New Soaring Pilot by Welch and Irving
has some good
information.

Thanks,

Paul Remde

'Bert Willing' wrote in
message ...
A TE probe on a wing would certainly be a very bad
idea as the pressure
field near the wing will not show linear variations
with angle of
attack...

--
Bert Willing

ASW20 'TW'


'Eric Greenwell' a écrit dans le message de
news:
...
Paul Remde wrote:
Hi,

I have a question for motorglider owners. I
sell
variometers and TE
probes
but I'm still learning. A customer is building
a
Europa motorglider
and
he
is wondering if he can mount a TE probe on the
fin
and connect it to
the
variometer, or will the propwash cause problems.

The reading will bounce around, but usable except
when trying to center
weak lift while under power.

Is it necessary to use
some sort of pneumatic switch to switch between
TE
and static input
for
the
variometer?

It would likely help.


His pitot and static ports are on a boom that
is
mounted to the wing.

Since he is building it, I suggest he consider a
TE tube on the wing,
clear of the prop wash. That should be easy, since
he is already doing
that with the pitot and static. Or, use a vario with
electronic TE and
just use the pitot/static.

--
Change 'netto' to 'net' to email me directly

Eric Greenwell
Washington State
USA