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Winter mechanical vario reading high



 
 
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  #1  
Old April 10th 06, 02:41 AM posted to rec.aviation.soaring
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Default Winter mechanical vario reading high

Last year my Winter mechanical variometer may have read a bit
high, but not very much. Today however, on my first flight of
the year, the vario appeared to read 400 feet high in the air and
about 75 feet high on the ground. With the vario reading 400
feet per minute up, the altimiter wasn't doing anything and the
Cambridge electric vario was reading zero sink.

I've searched the r.a.s. archives and found the advice about
zeroing the needle using the adjustment under the faceplate and
putting a trace of nail polish on the needle to weigh it down.

Do these seem like appropriate repairs for this problem?

Can anyone speculate on why the vario might read so much higher
in the air than on the ground? Is there a plumbing problem I
should look for to explain this?

Thanks for any ideas.

Alan


  #2  
Old April 10th 06, 02:47 AM posted to rec.aviation.soaring
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Default Winter mechanical vario reading high

Mine--(57mm) reads zero on the ground, but about 2 kt high in the air,
compared to a S-Nav. Yes I understand the "relative netto" thing, but this
occurs while thermaling at 48-52 kt in a DG800B, with the pneumatic switch
on "TE probe".
In addition, the Winter is faster in response than the S-Nav with the
Cambridge set on "fast" (1 sec). The DG factory installation has very short
leads off a "Y" to the S-Nav and Winter, but they are on separate
flasks--both 0.45l, with fairly long leads.

I'm guessing a very small leak in the Winter. I have just removed it and
will test tomorrow.

I thought it was just me!

--
Hartley Falbaum
"Alan Meyer" wrote in message
...
Last year my Winter mechanical variometer may have read a bit
high, but not very much. Today however, on my first flight of
the year, the vario appeared to read 400 feet high in the air and
about 75 feet high on the ground. With the vario reading 400
feet per minute up, the altimiter wasn't doing anything and the
Cambridge electric vario was reading zero sink.

I've searched the r.a.s. archives and found the advice about
zeroing the needle using the adjustment under the faceplate and
putting a trace of nail polish on the needle to weigh it down.

Do these seem like appropriate repairs for this problem?

Can anyone speculate on why the vario might read so much higher
in the air than on the ground? Is there a plumbing problem I
should look for to explain this?

Thanks for any ideas.

Alan




  #3  
Old April 10th 06, 03:48 AM posted to rec.aviation.soaring
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Posts: n/a
Default Winter mechanical vario reading high

Alan Meyer wrote:
Last year my Winter mechanical variometer may have read a bit
high, but not very much. Today however, on my first flight of
the year, the vario appeared to read 400 feet high in the air and
about 75 feet high on the ground. With the vario reading 400
feet per minute up, the altimiter wasn't doing anything and the
Cambridge electric vario was reading zero sink.

I've searched the r.a.s. archives and found the advice about
zeroing the needle using the adjustment under the faceplate and
putting a trace of nail polish on the needle to weigh it down.

Do these seem like appropriate repairs for this problem?

Can anyone speculate on why the vario might read so much higher
in the air than on the ground? Is there a plumbing problem I
should look for to explain this?

Thanks for any ideas.

Alan


I cannot explain 325 the 400 F/M error in the air but I think that I
can explain 75 F/M of it.

Previous posts on RAS may have explained this already so if this is
repetitious, my apologies.

The fluorescent material on the needle which
allows it to be visible at night, emits particles and over the years,
loses mass. It therefore eventually reads high. (I have never seen one
read low on the ground but it may be possible). There is an adjusting
screw behind the glass and has enough range for one or two adjustments
before it requires more fluorescent paint to put it back into range.

Paul
  #4  
Old April 10th 06, 04:22 AM posted to rec.aviation.soaring
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Default Winter mechanical vario reading high

Hartley,

Could you elaborate a bit on this explanation?

I would think that a leak would lead to a reduced response in all
modes - showing a reading closer to zero than should be, whether
going up or going down. I wouldn't expect a consistent up
indication - but maybe I'm not thinking about it correctly.

Thanks.

Incidentally, regarding the alternative explanations, my plane is
a 1966 era Libelle H301. The loss of flourescent paint seems
possible on a 40 year old plane, but I'm surprised to find the
effect so marked in just one year out of 40.

Alan

"HL Falbaum" wrote in message
news
Mine--(57mm) reads zero on the ground, but about 2 kt high in the air, compared to a
S-Nav. Yes I understand the "relative netto" thing, but this occurs while thermaling at
48-52 kt in a DG800B, with the pneumatic switch on "TE probe".
In addition, the Winter is faster in response than the S-Nav with the Cambridge set on
"fast" (1 sec). The DG factory installation has very short leads off a "Y" to the S-Nav
and Winter, but they are on separate flasks--both 0.45l, with fairly long leads.

I'm guessing a very small leak in the Winter. I have just removed it and will test
tomorrow.

I thought it was just me!

--
Hartley Falbaum
"Alan Meyer" wrote in message
...
Last year my Winter mechanical variometer may have read a bit
high, but not very much. Today however, on my first flight of
the year, the vario appeared to read 400 feet high in the air and
about 75 feet high on the ground. With the vario reading 400
feet per minute up, the altimiter wasn't doing anything and the
Cambridge electric vario was reading zero sink.

I've searched the r.a.s. archives and found the advice about
zeroing the needle using the adjustment under the faceplate and
putting a trace of nail polish on the needle to weigh it down.

Do these seem like appropriate repairs for this problem?

Can anyone speculate on why the vario might read so much higher
in the air than on the ground? Is there a plumbing problem I
should look for to explain this?

Thanks for any ideas.

Alan



  #5  
Old April 10th 06, 10:23 AM posted to rec.aviation.soaring
external usenet poster
 
Posts: n/a
Default Winter mechanical vario reading high

Pneumatic total energy relies on applying a partial
vacuum (proportional to airspeed) on the static side
of the vario. If you have a leak on the flask side,
then the partial vacuum results in a flow through the
vario and apparent climb. A leak on the total energy
side would just result in poor compensation.

You also mention long plumbing to the flask, this adds
to the total volume on the flask side and can make
the vario over read both lift and sink.

At 03:18 10 April 2006, Alan Meyer wrote:
Hartley,

Could you elaborate a bit on this explanation?

I would think that a leak would lead to a reduced response
in all
modes - showing a reading closer to zero than should
be, whether
going up or going down. I wouldn't expect a consistent
up
indication - but maybe I'm not thinking about it correctly.

Thanks.

Incidentally, regarding the alternative explanations,
my plane is
a 1966 era Libelle H301. The loss of flourescent paint
seems
possible on a 40 year old plane, but I'm surprised
to find the
effect so marked in just one year out of 40.

Alan

'HL Falbaum' wrote in message
news
Mine--(57mm) reads zero on the ground, but about 2
kt high in the air, compared to a
S-Nav. Yes I understand the 'relative netto' thing,
but this occurs while thermaling at
48-52 kt in a DG800B, with the pneumatic switch on
'TE probe'.
In addition, the Winter is faster in response than
the S-Nav with the Cambridge set on
'fast' (1 sec). The DG factory installation has very
short leads off a 'Y' to the S-Nav
and Winter, but they are on separate flasks--both
0.45l, with fairly long leads.

I'm guessing a very small leak in the Winter. I have
just removed it and will test
tomorrow.

I thought it was just me!

--
Hartley Falbaum
'Alan Meyer' wrote in message
...
Last year my Winter mechanical variometer may have
read a bit
high, but not very much. Today however, on my first
flight of
the year, the vario appeared to read 400 feet high
in the air and
about 75 feet high on the ground. With the vario
reading 400
feet per minute up, the altimiter wasn't doing anything
and the
Cambridge electric vario was reading zero sink.

I've searched the r.a.s. archives and found the advice
about
zeroing the needle using the adjustment under the
faceplate and
putting a trace of nail polish on the needle to weigh
it down.

Do these seem like appropriate repairs for this problem?

Can anyone speculate on why the vario might read so
much higher
in the air than on the ground? Is there a plumbing
problem I
should look for to explain this?

Thanks for any ideas.

Alan







  #6  
Old April 10th 06, 01:37 PM posted to rec.aviation.soaring
external usenet poster
 
Posts: n/a
Default Winter mechanical vario reading high

Cause is leak on the capacitiy side of the vario.
If you have the varios in series, the likely cause will bea leak on the
sensor board of the Cambridge.
Otherwise, just replace the tubing between the capacity and the Winter-
it's probably hard as a rock.
Good Luck
UH

  #7  
Old April 10th 06, 02:47 PM posted to rec.aviation.soaring
external usenet poster
 
Posts: n/a
Default Winter mechanical vario reading high

The TE head generates a low pressure at the sensor holes on the back of the
tube, so that if there is a leak in the system on the flask side of the
Winter vario, then it appears to me that the TE pressure will draw air out
even whilst the glider is holding a steady height. Hence, Winter vario
reads up. Change tubing downstream of the vario and change the flask for
one you have confidence is leak free - best is a replacement flask of the
same kind. Fly the glider again. If the problem persists this may suggest
the leak is with the Winter vario. Flasks can have leaks and tubing can
fracture or be old and not sealing at the barbs on the vario or flask
connections.

The ground problem is either due to needle out of balance or needle zero
setting error I would suggest. These are actually two seperate problems. I
suggest that the adjustment under the faceplate is provided to adjust the
zero needle position as controlled by zeroing springs and after the needle
is balanced. The problem is usually a needle balance problem. Fix a
balance problem by use of paint on the needle. See my posting at the end of
the thread on this topic which appeared starting 27 March 2006.

For completeness I will repeat he
The factors a
1. The state of balance of the needle about the pivot - as affected by
the balance state of the needle.
2. The influence of zero setting springs - as affected by the serated
ring exposed under the little cover at the vario face centre (as with Winter
varios).

When we find that the vario at rest has the needle away from zero (with
Winter variometers usually 0.5 to 1 kt up due loss of solvents from the
white paint, and with PZL ofen down due ?? to luminescent paint absoring and
holding moisture??), what result do we want from our efforts to correct it?
I would suggest we want the outcome to be that the vario needle at rest sits
at zero both with the vario in both upright and inverted (ie rolled 180
degrees about the needle shaft axis) positions.

At rest hold the vario upright and note the needle position, and then hold
it inverted and note the needle position. From that information you can get
an idea as to whether it is a problem of needle balance (1 above) or zero
setting (2 above), or a mix of the two. For example a needle out of balance
of + 1 knot upright will show -1 knot with vario inverted.

Mostly it is a matter of 1 above. In the case of 1, fixing it by using the
zero setting springs via the serated ring will zero the needle with
variometer upright but not inverted! If it is a needle balance problem then
you need to fix the needle balance, not alter the zeroing springs. If you
fix the needle balance, then the needle will not respond to accelerations
during pullups, gusts, etc which is a better outcome.

I use paint placed close to the needle pivot because so little is needed to
produce balance. I use a broken hacksaw blade ground to length (and using
the plain edge not the serrated edge) to engage the ring
and facilitate its removal and reinstallation. Rather than fit the blade
element to a piece of timber to create a tool, I put the blade element in a
bench vise and hold the vario down onto the blade element. Then you get
precise control of the undoing and particularly the doing up force/torque.

Don't give the job to your local club member-gorrilla!

I welcome any contribution to improving the understanding presented above.
Cheers

Roger Druce




"Alan Meyer" wrote in message
...
Last year my Winter mechanical variometer may have read a bit
high, but not very much. Today however, on my first flight of
the year, the vario appeared to read 400 feet high in the air and
about 75 feet high on the ground. With the vario reading 400
feet per minute up, the altimiter wasn't doing anything and the
Cambridge electric vario was reading zero sink.

I've searched the r.a.s. archives and found the advice about
zeroing the needle using the adjustment under the faceplate and
putting a trace of nail polish on the needle to weigh it down.

Do these seem like appropriate repairs for this problem?

Can anyone speculate on why the vario might read so much higher
in the air than on the ground? Is there a plumbing problem I
should look for to explain this?

Thanks for any ideas.

Alan




  #8  
Old April 10th 06, 02:47 PM posted to rec.aviation.soaring
external usenet poster
 
Posts: n/a
Default Winter mechanical vario reading high

Found it!

The vinyl tubing is 8+ years old, and leaking at both ends of the flask
tube. The fit looked only slightly less than tight. The tube was not hard as
a rock but firmer than new tubing. The S-Nav and Winter are paralllel, not
series. Cutting off the vario end of the tube reduced, but did not eliminate
the leak. Then cutting off the flask end eliminated the rest of the leak.
Testing the vario alone proved it was leak free.

Thanks UH.
-
Hartley Falbaum
"KF"

wrote in message
oups.com...
Cause is leak on the capacitiy side of the vario.
If you have the varios in series, the likely cause will bea leak on the
sensor board of the Cambridge.
Otherwise, just replace the tubing between the capacity and the Winter-
it's probably hard as a rock.
Good Luck
UH



  #9  
Old April 10th 06, 03:55 PM posted to rec.aviation.soaring
external usenet poster
 
Posts: n/a
Default Winter mechanical vario reading high


Roger Druce wrote:
The TE head generates a low pressure at the sensor holes on the back of the
tube, so that if there is a leak in the system on the flask side of the
Winter vario, then it appears to me that the TE pressure will draw air out
even whilst the glider is holding a steady height. Hence, Winter vario
reads up. Change tubing downstream of the vario and change the flask for
one you have confidence is leak free - best is a replacement flask of the
same kind. Fly the glider again. If the problem persists this may suggest
the leak is with the Winter vario. Flasks can have leaks and tubing can
fracture or be old and not sealing at the barbs on the vario or flask
connections.

The ground problem is either due to needle out of balance or needle zero
setting error I would suggest. These are actually two seperate problems. I
suggest that the adjustment under the faceplate is provided to adjust the
zero needle position as controlled by zeroing springs and after the needle
is balanced. The problem is usually a needle balance problem. Fix a
balance problem by use of paint on the needle. See my posting at the end of
the thread on this topic which appeared starting 27 March 2006.

For completeness I will repeat he
The factors a
1. The state of balance of the needle about the pivot - as affected by
the balance state of the needle.
2. The influence of zero setting springs - as affected by the serated
ring exposed under the little cover at the vario face centre (as with Winter
varios).

When we find that the vario at rest has the needle away from zero (with
Winter variometers usually 0.5 to 1 kt up due loss of solvents from the
white paint, and with PZL ofen down due ?? to luminescent paint absoring and
holding moisture??), what result do we want from our efforts to correct it?
I would suggest we want the outcome to be that the vario needle at rest sits
at zero both with the vario in both upright and inverted (ie rolled 180
degrees about the needle shaft axis) positions.

At rest hold the vario upright and note the needle position, and then hold
it inverted and note the needle position. From that information you can get
an idea as to whether it is a problem of needle balance (1 above) or zero
setting (2 above), or a mix of the two. For example a needle out of balance
of + 1 knot upright will show -1 knot with vario inverted.

Mostly it is a matter of 1 above. In the case of 1, fixing it by using the
zero setting springs via the serated ring will zero the needle with
variometer upright but not inverted! If it is a needle balance problem then
you need to fix the needle balance, not alter the zeroing springs. If you
fix the needle balance, then the needle will not respond to accelerations
during pullups, gusts, etc which is a better outcome.

I use paint placed close to the needle pivot because so little is needed to
produce balance. I use a broken hacksaw blade ground to length (and using
the plain edge not the serrated edge) to engage the ring
and facilitate its removal and reinstallation. Rather than fit the blade
element to a piece of timber to create a tool, I put the blade element in a
bench vise and hold the vario down onto the blade element. Then you get
precise control of the undoing and particularly the doing up force/torque.

Don't give the job to your local club member-gorrilla!

I welcome any contribution to improving the understanding presented above.
Cheers

Roger Druce




"Alan Meyer" wrote in message
...
Last year my Winter mechanical variometer may have read a bit
high, but not very much. Today however, on my first flight of
the year, the vario appeared to read 400 feet high in the air and
about 75 feet high on the ground. With the vario reading 400
feet per minute up, the altimiter wasn't doing anything and the
Cambridge electric vario was reading zero sink.

I've searched the r.a.s. archives and found the advice about
zeroing the needle using the adjustment under the faceplate and
putting a trace of nail polish on the needle to weigh it down.

Do these seem like appropriate repairs for this problem?

Can anyone speculate on why the vario might read so much higher
in the air than on the ground? Is there a plumbing problem I
should look for to explain this?

Thanks for any ideas.

Alan



Hi
About 5 years ago I sent my vario and airspeed to Winter. Everything
came back as new. Cost about $100 for each instrument including
shipping. Best deal IMO.
December is probably the best time of year to use this solution
S6

  #10  
Old April 10th 06, 05:39 PM posted to rec.aviation.soaring
external usenet poster
 
Posts: n/a
Default Winter mechanical vario reading high

Hi,
You are assuming the identified problem is real. It could be something
else. You are using this problem so you can use the solution you have.
Adding paint is just convenient. Send it to Winter.
S6

 




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