So we have this plain mechanical vario in a glider, connected to a TE
probe and a flask. The TE probe is also connected to an electronic
vario with a pressure sensor, which is not ideal for the electronic
vario, but shouldn't affect the mechanical one much. While thermaling,
the mechanical vario shows lift, varying similarly to what the
electronic one shows. But while cruising, the mechanical vario is continuously PEGGED DOWN. Well sometimes for a little while it is not
quite pegged, but still way down, around -8 knots. At the same time the electronic one (if the Speed Control function is turned off) is showing reasonable and varying sink rates. What could cause that behavior?
So we have this plain mechanical vario in a glider, connected to a TE
probe and a flask. The TE probe is also connected to an electronic
vario with a pressure sensor, which is not ideal for the electronic
vario, but shouldn't affect the mechanical one much. While thermaling,
the mechanical vario shows lift, varying similarly to what the
electronic one shows. But while cruising, the mechanical vario is continuously PEGGED DOWN. Well sometimes for a little while it is not
quite pegged, but still way down, around -8 knots. At the same time the electronic one (if the Speed Control function is turned off) is showing reasonable and varying sink rates. What could cause that behavior?
On Tuesday, August 16, 2022 at 10:18:26 PM UTC-4, Moshe Braner wrote:Check for vario case leaks; glass seal.
So we have this plain mechanical vario in a glider, connected to a TEDon't outthink this one.
probe and a flask. The TE probe is also connected to an electronic
vario with a pressure sensor, which is not ideal for the electronic
vario, but shouldn't affect the mechanical one much. While thermaling,
the mechanical vario shows lift, varying similarly to what the
electronic one shows. But while cruising, the mechanical vario is continuously PEGGED DOWN. Well sometimes for a little while it is not
quite pegged, but still way down, around -8 knots. At the same time the electronic one (if the Speed Control function is turned off) is showing reasonable and varying sink rates. What could cause that behavior?
1)Never connect varios in series.
2) If using a common TE source connect as far away from variometers as possible.
3) Leak check circuits independently.
4) Verify correct connections.
UH
On Tue, 16 Aug 2022 22:18:22 -0400, Moshe Braner wrote:
So we have this plain mechanical vario in a glider, connected to a TE
probe and a flask. The TE probe is also connected to an electronic
vario with a pressure sensor, which is not ideal for the electronic
vario, but shouldn't affect the mechanical one much. While thermaling,
the mechanical vario shows lift, varying similarly to what the
electronic one shows. But while cruising, the mechanical vario is
continuously PEGGED DOWN. Well sometimes for a little while it is not
quite pegged, but still way down, around -8 knots. At the same time the
electronic one (if the Speed Control function is turned off) is showing
reasonable and varying sink rates. What could cause that behavior?
Where is the T split in the line from the TE probe.
In http://www.borgeltinstruments.com/?page_id=248 there's a note that
says:
"Note that other instruments with flasks can affect the response of the BORGELT variometers which can be avoided by splitting the TE line well aft from the instrument panel. Under the rear of the seat pan will work well. This does not apply for instruments without flasks like the B21/B40/B50/ B100/B400/B500/B600/B700/B800/B900 and other variometers which work on the silicon pressure sensor principle."
I know that this is the opposite problem to what you're seeing but it may still be relevant. Could there be a leak on the flask side of the
mechanical vario? (unsupported guess by me).
On Wednesday, August 17, 2022 at 8:31:41 AM UTC-4, Hank Nixon wrote:IMHO "checking for leaks" without the right equipment and knowing exactly where leaks can occur is an exercise in futility. At a minimum, you need a combo pressure-vacuum gauge, designed plugs, syringe, valve, and several hours of watching time to
On Tuesday, August 16, 2022 at 10:18:26 PM UTC-4, Moshe Braner wrote:Check for vario case leaks; glass seal.
So we have this plain mechanical vario in a glider, connected to a TE probe and a flask. The TE probe is also connected to an electronicDon't outthink this one.
vario with a pressure sensor, which is not ideal for the electronic vario, but shouldn't affect the mechanical one much. While thermaling, the mechanical vario shows lift, varying similarly to what the electronic one shows. But while cruising, the mechanical vario is continuously PEGGED DOWN. Well sometimes for a little while it is not quite pegged, but still way down, around -8 knots. At the same time the electronic one (if the Speed Control function is turned off) is showing reasonable and varying sink rates. What could cause that behavior?
1)Never connect varios in series.
2) If using a common TE source connect as far away from variometers as possible.
3) Leak check circuits independently.
4) Verify correct connections.
UH
JMF
Sounds like you have problem with mechanical vario. Hard to imagine scenario where static leak would not be visible on both instruments.
On Wednesday, August 17, 2022 at 9:15:30 AM UTC-4, john firth wrote:detect tiny leaks. (And don't forget to cut off both ends of the suspect tubing where they stretch over their fittings.) Any over or under pressure of a device can ruin it, so know what you are doing. Easier and cheaper: Replace the suspect lines. Last
On Wednesday, August 17, 2022 at 8:31:41 AM UTC-4, Hank Nixon wrote:IMHO "checking for leaks" without the right equipment and knowing exactly where leaks can occur is an exercise in futility. At a minimum, you need a combo pressure-vacuum gauge, designed plugs, syringe, valve, and several hours of watching time to
On Tuesday, August 16, 2022 at 10:18:26 PM UTC-4, Moshe Braner wrote:Check for vario case leaks; glass seal.
So we have this plain mechanical vario in a glider, connected to a TE probe and a flask. The TE probe is also connected to an electronic vario with a pressure sensor, which is not ideal for the electronic vario, but shouldn't affect the mechanical one much. While thermaling, the mechanical vario shows lift, varying similarly to what the electronic one shows. But while cruising, the mechanical vario is continuously PEGGED DOWN. Well sometimes for a little while it is not quite pegged, but still way down, around -8 knots. At the same time theDon't outthink this one.
electronic one (if the Speed Control function is turned off) is showing
reasonable and varying sink rates. What could cause that behavior?
1)Never connect varios in series.
2) If using a common TE source connect as far away from variometers as possible.
3) Leak check circuits independently.
4) Verify correct connections.
UH
JMF
On 8/17/2022 10:28 AM, krasw wrote:
Sounds like you have problem with mechanical vario. Hard to imagine scenario where
static leak would not be visible on both instruments.
Yup. I can't think of any point in the system where just an air leak would explain the
behavior we're seeing. Unless the e-vario pumps air out of its TE port the whole time
you're cruising... Would be nice to have an hypothesis on what COULD be the problem.
Otherwise it's shooting in the dark. Perhaps we should start by inserting a different
mechanical vario into the same air lines and compare the behavior?
On Wednesday, August 17, 2022 at 9:15:30 AM UTC-4, john firth wrote:detect tiny leaks. (And don't forget to cut off both ends of the suspect tubing where they stretch over their fittings.) Any over or under pressure of a device can ruin it, so know what you are doing. Easier and cheaper: Replace the suspect lines. Last
On Wednesday, August 17, 2022 at 8:31:41 AM UTC-4, Hank Nixon wrote:IMHO "checking for leaks" without the right equipment and knowing exactly where leaks can occur is an exercise in futility. At a minimum, you need a combo pressure-vacuum gauge, designed plugs, syringe, valve, and several hours of watching time to
On Tuesday, August 16, 2022 at 10:18:26 PM UTC-4, Moshe Braner wrote:Check for vario case leaks; glass seal.
So we have this plain mechanical vario in a glider, connected to a TE probe and a flask. The TE probe is also connected to an electronic vario with a pressure sensor, which is not ideal for the electronic vario, but shouldn't affect the mechanical one much. While thermaling, the mechanical vario shows lift, varying similarly to what the electronic one shows. But while cruising, the mechanical vario is continuously PEGGED DOWN. Well sometimes for a little while it is not quite pegged, but still way down, around -8 knots. At the same time theDon't outthink this one.
electronic one (if the Speed Control function is turned off) is showing
reasonable and varying sink rates. What could cause that behavior?
1)Never connect varios in series.
2) If using a common TE source connect as far away from variometers as possible.
3) Leak check circuits independently.
4) Verify correct connections.
UH
JMF
On 8/17/2022 10:28 AM, krasw wrote:
Sounds like you have problem with mechanical vario. Hard to imagine
scenario where static leak would not be visible on both instruments.
Yup. I can't think of any point in the system where just an air leak
would explain the behavior we're seeing. Unless the e-vario pumps air
out of its TE port the whole time you're cruising... Would be nice to
have an hypothesis on what COULD be the problem. Otherwise it's
shooting in the dark. Perhaps we should start by inserting a different mechanical vario into the same air lines and compare the behavior?
On 8/17/2022 7:41 AM, Moshe Braner wrote:
On 8/17/2022 10:28 AM, krasw wrote:Does TE seem to work? Can you duplicate the problem on the ground?
Sounds like you have problem with mechanical vario. Hard to imagine
scenario where static leak would not be visible on both instruments.
Yup. I can't think of any point in the system where just an air leak
would explain the behavior we're seeing. Unless the e-vario pumps air
out of its TE port the whole time you're cruising... Would be nice to
have an hypothesis on what COULD be the problem. Otherwise it's
shooting in the dark. Perhaps we should start by inserting a
different mechanical vario into the same air lines and compare the
behavior?
My guess is the mechanical vario has a leak. Substitute another
mechanical vario, and test again.
You might be able to test the vario without flying, by blocking the port
to the flask with short, plugged piece of tubing, and gently blowing on
a tube connected to the TE/Static port. The needle on a leaky vario will
show sink; the needle on a good vario should remain still.
On 8/17/2022 12:23 PM, Eric Greenwell wrote:
On 8/17/2022 7:41 AM, Moshe Braner wrote:
On 8/17/2022 10:28 AM, krasw wrote:Does TE seem to work? Can you duplicate the problem on the ground?
Sounds like you have problem with mechanical vario. Hard to imagine scenario where
static leak would not be visible on both instruments.
Yup. I can't think of any point in the system where just an air leak would explain the
behavior we're seeing. Unless the e-vario pumps air out of its TE port the whole time
you're cruising... Would be nice to have an hypothesis on what COULD be the problem.
Otherwise it's shooting in the dark. Perhaps we should start by inserting a different
mechanical vario into the same air lines and compare the behavior?
My guess is the mechanical vario has a leak. Substitute another mechanical vario, and
test again.
You might be able to test the vario without flying, by blocking the port to the flask
with short, plugged piece of tubing, and gently blowing on a tube connected to the
TE/Static port. The needle on a leaky vario will show sink; the needle on a good vario
should remain still.
Right. But if instead you could SUCK on the TE/Static port, the leaky vario would show
LIFT. In flight, the pressure from the TE probe is LOWER than the static, or cabin
pressure. I.e., a leaky vario, or flask, or connection to flask, should cause the
instrument to show LIFT. Why is the vario in question showing massive SINK (pegged
down)? And why only in cruise? It is showing reasonable lift while circling in a thermal.
I suppose we should carefully try a slow cruise, at speeds used in thermaling, and see if
what determines the vario's "cruise" behavior is the air speed. But so far we haven't
noticed a relationship to airspeed. So perhaps what causes the instrument to peg down "in
cruise" is the fact that it is in sink at all? Could the instrument be defective in a way
that causes the needle deflection to be much too large in sink, but normal (or not very
large) in lift?
To be specific, it is a standard Winter brand 80mm mechanical vario, and it is probably
some 40 years old.
Mike Borgelt of Borgelt Instruments has a good overview about pneumatic leaks in glider instruments. It covers detection, diagnosis and repair of leaks. The article can be found here: http://www.borgeltinstruments.com/?page_id=252. Additionally, LeeKuhlke had an article in Soaring magazine from around 2005 that covered the same topic. I have referred to both when chasing down problems in several gliders.
On Wednesday, August 17, 2022 at 2:09:43 PM UTC-4, Mark Mocho wrote:Kuhlke had an article in Soaring magazine from around 2005 that covered the same topic. I have referred to both when chasing down problems in several gliders.
Mike Borgelt of Borgelt Instruments has a good overview about pneumatic leaks in glider instruments. It covers detection, diagnosis and repair of leaks. The article can be found here: http://www.borgeltinstruments.com/?page_id=252. Additionally, Lee
Caution with this link. I got a security alert.
On 8/17/2022 10:42 AM, Moshe Braner wrote:
On 8/17/2022 12:23 PM, Eric Greenwell wrote:The difference in behavior between thermalling and cruise might be due
On 8/17/2022 7:41 AM, Moshe Braner wrote:
On 8/17/2022 10:28 AM, krasw wrote:Does TE seem to work? Can you duplicate the problem on the ground?
Sounds like you have problem with mechanical vario. Hard to imagine
scenario where static leak would not be visible on both instruments. >>>>>
Yup. I can't think of any point in the system where just an air
leak would explain the behavior we're seeing. Unless the e-vario
pumps air out of its TE port the whole time you're cruising...
Would be nice to have an hypothesis on what COULD be the problem.
Otherwise it's shooting in the dark. Perhaps we should start by
inserting a different mechanical vario into the same air lines and
compare the behavior?
My guess is the mechanical vario has a leak. Substitute another
mechanical vario, and test again.
You might be able to test the vario without flying, by blocking the
port to the flask with short, plugged piece of tubing, and gently
blowing on a tube connected to the TE/Static port. The needle on a
leaky vario will show sink; the needle on a good vario should remain
still.
Right. But if instead you could SUCK on the TE/Static port, the leaky
vario would show LIFT. In flight, the pressure from the TE probe is
LOWER than the static, or cabin pressure. I.e., a leaky vario, or
flask, or connection to flask, should cause the instrument to show
LIFT. Why is the vario in question showing massive SINK (pegged
down)? And why only in cruise? It is showing reasonable lift while
circling in a thermal.
I suppose we should carefully try a slow cruise, at speeds used in
thermaling, and see if what determines the vario's "cruise" behavior
is the air speed. But so far we haven't noticed a relationship to
airspeed. So perhaps what causes the instrument to peg down "in
cruise" is the fact that it is in sink at all? Could the instrument
be defective in a way that causes the needle deflection to be much too
large in sink, but normal (or not very large) in lift?
To be specific, it is a standard Winter brand 80mm mechanical vario,
and it is probably some 40 years old.
to cockpit pressure, which might affect a leak.
Followup: We replaced the mechanical vario with another mechanical
vario we had on hand, using the existing TE probe, flask, and plumbing.
In flight it correctly showed lift and sink, the same as the
electronic vario. The TE compensation seems good.
So presumably the old vario itself is faulty. I wonder how it's built
inside, and what internal malfunction would make it work normally for
lift but greatly over-react to sink.
I would inspect the gasket sealing the glass to the bezel. Variometers are dependent on the case being sealed from the outside air pressure. Assuming the fittings are sound and the case is not cracked, the glass to bezel seal is suspect.
Followup: We replaced the mechanical vario with another mechanical
vario we had on hand, using the existing TE probe, flask, and plumbing.
In flight it correctly showed lift and sink, the same as the
electronic vario. The TE compensation seems good.
So presumably the old vario itself is faulty. I wonder how it's built
inside, and what internal malfunction would make it work normally for
lift but greatly over-react to sink.
Why would that affect the reading asymmetrically, with the ups showing normally and the downs greatly amplified?
On Monday, September 12, 2022 at 9:47:38 PM UTC-4, Moshe Braner wrote:off. if it changes when going to face vertical it is an indication that the needle weight is not balanced. Correction is to center with the face up and then add a small amount of weight to the needle. I use a tiny drop of epoxy. Iyt is delicate work ,
On 9/12/2022 9:40 PM, Mark Mocho wrote:
Why would that affect the reading asymmetrically, with the ups showing
Followup: We replaced the mechanical vario with another mechanical
vario we had on hand, using the existing TE probe, flask, and plumbing. >>>> In flight it correctly showed lift and sink, the same as the
electronic vario. The TE compensation seems good.
So presumably the old vario itself is faulty. I wonder how it's built
inside, and what internal malfunction would make it work normally for
lift but greatly over-react to sink.
I would inspect the gasket sealing the glass to the bezel. Variometers are dependent on the case being sealed from the outside air pressure. Assuming the fittings are sound and the case is not cracked, the glass to bezel seal is suspect.
normally and the downs greatly amplified?
One possibility is that it was worked on by someone. Mechanical variometers, such as Winter varios, have a light spring that centers them that is connected to the needle assembly and an adjustment disc. It is used to center the instrument at assembly.
Over time the needle can become lighter, due to drying out of the paint, and even flaking off. Rotating the adjustment disc can re center the instrument but it unbalances the response. Holding the instrument face up will indicate if the adjustment is
Also while doing all of this is make sure there are no case leaks.
UH
On 9/12/2022 9:40 PM, Mark Mocho wrote:
Followup: We replaced the mechanical vario with another mechanical
vario we had on hand, using the existing TE probe, flask, and plumbing. >> In flight it correctly showed lift and sink, the same as the
electronic vario. The TE compensation seems good.
So presumably the old vario itself is faulty. I wonder how it's built
inside, and what internal malfunction would make it work normally for
lift but greatly over-react to sink.
I would inspect the gasket sealing the glass to the bezel. Variometers are dependent on the case being sealed from the outside air pressure. Assuming the fittings are sound and the case is not cracked, the glass to bezel seal is suspect.
Why would that affect the reading asymmetrically, with the ups showing normally and the downs greatly amplified?
I have a friend that has sent several back to Winter to be rebuilt, but I do not know the cost of the work.I had a 57mm overhauled & new case 2 years ago. Can't find the exact amount but it was cheaper than buying a replacement. I subsequently found someone selling a used one for about the same price but was happy to get mine back with new papers🤷♂️
Kevin
92
I had a 57mm overhauled & new case 2 years ago. Can't find the exact amount but it was cheaper than buying a replacement. I subsequently found someone selling a used one for about the same price but was happy to get mine back with new papers🤷�♂��
Meanwhile, we've apparently fixed the vario using the method UH
mentioned. Will report after testing it in flight.
On 9/19/2022 9:13 AM, Moshe Braner wrote:
Meanwhile, we've apparently fixed the vario using the method UHWorked fine in an actual flight. Yay!
mentioned. Will report after testing it in flight.
On 9/19/2022 9:13 AM, Moshe Braner wrote:I'm late in this conversation. Glad that this problem was fixed.
Meanwhile, we've apparently fixed the vario using the method UHWorked fine in an actual flight. Yay!
mentioned. Will report after testing it in flight.
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