Topics

Superpressure balloon valve / was Re: [GPSL] K5NOT-11 WSPR Balloon Failure


Bill Brown
 

I managed to float a couple of 1200 and 1500 gram balloons by putting a PVC pipe with an end cap in the neck of the balloon and drilling a 1/16" hole in the end cap (two 1/16" holes were too much as were larger size drill holes). The ones with the single 1/16" hole all floated all night long over 100,000 feet or so. 

- Bill WB8ELK


-----Original Message-----
From: BASE_DePauw <hlbrooks@...>
To: GPSL@groups.io
Sent: Tue, Jul 21, 2020 9:27 pm
Subject: Re: Superpressure balloon valve / was  Re: [GPSL] K5NOT-11 WSPR Balloon Failure

I suggest reaching out to Michael K5NOT (ARBONET) who did the presentation at GPSL 2010.

Another investigator was James Flaten with his students at the University of Minnesota who shared their results at the Academic High Altitude Conference that same summer at Taylor University.

I cannot find copies of either presentation in my files tonight.

Howard, KC9QBN
BASE_DePauw



On Tue, Jul 21, 2020 at 10:12 PM Mark Conner N9XTN <mconner1@...> wrote:
I searched my Gmail archive and there are fragments of a discussion on this topic based on an ARBONET balloon flight in the summer of 2010 which may have measured this.  There may even have been a GPSL presentation that summer on it.  If you look in the archived messages from ~June-Sept 2010 you may find something.

GPSL 2010 was in Hutchinson KS.

73 de Mark N9XTN

On Tue, Jul 21, 2020 at 7:40 PM Dennis Klipa - N8ERF <klipadk@...> wrote:
I am curious.  Many of us have measured the atmospheric pressure versus altitude.  I have wanted to, but haven't, measured the pressure inside the latex balloon as it rises.  Has anyone measured the pressure differential (inside vs outside) of the latex balloon as a function of altitude?  How much difference are we talking about trying to control with this valve.  If the balloon were a fixed volume you could do the calculation, but the latex balloons are not.

Best Regards,
Dennis Klipa, N8ERF



--
Howard L. Brooks
Professor of Physics and Astronomy
241 Julian Science and Mathematics Center
DePauw University
2 E. Hanna Street
Greencastle, IN 46135
hlbrooks@...


BASE_DePauw
 

I suggest reaching out to Michael K5NOT (ARBONET) who did the presentation at GPSL 2010.

Another investigator was James Flaten with his students at the University of Minnesota who shared their results at the Academic High Altitude Conference that same summer at Taylor University.

I cannot find copies of either presentation in my files tonight.

Howard, KC9QBN
BASE_DePauw



On Tue, Jul 21, 2020 at 10:12 PM Mark Conner N9XTN <mconner1@...> wrote:
I searched my Gmail archive and there are fragments of a discussion on this topic based on an ARBONET balloon flight in the summer of 2010 which may have measured this.  There may even have been a GPSL presentation that summer on it.  If you look in the archived messages from ~June-Sept 2010 you may find something.

GPSL 2010 was in Hutchinson KS.

73 de Mark N9XTN

On Tue, Jul 21, 2020 at 7:40 PM Dennis Klipa - N8ERF <klipadk@...> wrote:
I am curious.  Many of us have measured the atmospheric pressure versus altitude.  I have wanted to, but haven't, measured the pressure inside the latex balloon as it rises.  Has anyone measured the pressure differential (inside vs outside) of the latex balloon as a function of altitude?  How much difference are we talking about trying to control with this valve.  If the balloon were a fixed volume you could do the calculation, but the latex balloons are not.

Best Regards,
Dennis Klipa, N8ERF




--
Howard L. Brooks
Professor of Physics and Astronomy
241 Julian Science and Mathematics Center
DePauw University
2 E. Hanna Street
Greencastle, IN 46135
hlbrooks@...


Mark Conner N9XTN
 

I searched my Gmail archive and there are fragments of a discussion on this topic based on an ARBONET balloon flight in the summer of 2010 which may have measured this.  There may even have been a GPSL presentation that summer on it.  If you look in the archived messages from ~June-Sept 2010 you may find something.

GPSL 2010 was in Hutchinson KS.

73 de Mark N9XTN

On Tue, Jul 21, 2020 at 7:40 PM Dennis Klipa - N8ERF <klipadk@...> wrote:
I am curious.  Many of us have measured the atmospheric pressure versus altitude.  I have wanted to, but haven't, measured the pressure inside the latex balloon as it rises.  Has anyone measured the pressure differential (inside vs outside) of the latex balloon as a function of altitude?  How much difference are we talking about trying to control with this valve.  If the balloon were a fixed volume you could do the calculation, but the latex balloons are not.

Best Regards,
Dennis Klipa, N8ERF



Dennis Klipa - N8ERF
 

Thanks for looking.  I assume the data was consistent with the data you shared.

Dennis

On Tue, Jul 21, 2020, 9:33 PM Jerry via groups.io <jerrygable=yahoo.com@groups.io> wrote:
Correct.  I also did a test during a flight but couldn't find the data.

Jerry


On Tue, Jul 21, 2020 at 6:31 PM, Dennis Klipa - N8ERF
<klipadk@...> wrote:
Jerry,

Thanks for the data.  Pretty small differential.  I assume that the graph shows the differential pressure vs time during which you added gas to the balloon at a more or less constant rate.  Is that correct?

Best Regards,
Dennis, N8ERF

On Tue, Jul 21, 2020, 9:19 PM Jerry via groups.io <jerrygable=yahoo.com@groups.io> wrote:
I did some experiments on the differential pressure on a balloon  This was a ground test on a fairly small latex balloon (100 Grams I believe)  but larger ones would be similar.  As you approach burst the diff. pressure rises. 

A good analogy is a rubber band.  There is a high force for the initial stretch of a new band then it drops off.  The pressure increases as you reach the breaking point.

The pressure doesn't change much on a balloon so you have to be pretty accurate if you want to obtain float wit a latex balloon.  It has been done with a very low amount of lift gas.

I suspect a Mylar balloon would have a sharper curve since they don't stretch but I haven't done any burst experiments with those.


Inline image


Jerry Gable
Balloon Flight Prediction tools
http://www.s3research.com


On Tuesday, July 21, 2020, 6:05:54 PM MST, Joe WB9SBD <nss@...> wrote:


I did have these numbers, But it was a long time ago.

The numbers I got I did it by testing a piece of the envelope it's tensile strength, and doing the tons of math to learn what the pressure differential would be.

What was interesting was someone ( do not remember who) actually did flight(s) with a pressure sensor.
The neat part was my measured of material and the math calculations, the number I got was within like 5% of what they measured.

Joe WB9SBD

On 7/21/2020 7:39 PM, Dennis Klipa - N8ERF wrote:
I am curious.  Many of us have measured the atmospheric pressure versus altitude.  I have wanted to, but haven't, measured the pressure inside the latex balloon as it rises.  Has anyone measured the pressure differential (inside vs outside) of the latex balloon as a function of altitude?  How much difference are we talking about trying to control with this valve.  If the balloon were a fixed volume you could do the calculation, but the latex balloons are not.

Best Regards,
Dennis Klipa, N8ERF

On Tue, Jul 21, 2020, 8:23 PM Joe WB9SBD <nss@...> wrote:
It was a 1500 Kaymont balloon.

Knowing the pressure differential is extremely low. When I tested the ping pong ball, I know it leaked badly. The texture of the ball just would not give a good seal.

I went with the silicone on both the "O" ring and the ball.

I also went with a pressure of the spring, Actually a spring I just could not find a spring suitable.  So I used a left over strip of balloon latex, attached to the ball and to a acrylic shaft.

The shaft was rotated to tighten the tension on the ball and seal.

I made it as loose as possible,, just enough to make the seal, and I mean barely!

I was worried that motion would even break the seal. It was that slight.

Even as light as that was,  it was not light enough, the flight still had a standard flight profile with rise to burst altitude, and did still pop.

Joe WB9SBD

On 7/21/2020 3:41 PM, Hank Riley via groups.io wrote:
Joe, please tell us more.  

Latex or other envelope?  How did it work out for you?  Any special reason for trying this valve method out?  What altitude was reached?   How long did it remain in the air?
___________________________________________________________


On Sunday, July 19, 2020, 09:06:33 AM EDT, Joe wrote:

I did that once. But the ping pong ball surface is too textured and does not make a bubble tight seal. I did a silicone ball and o ring.




Joe WB9SBD
 

I remember the data that matched mine, was the actual flying flight.

There was a small but very detectable spike just before burst.

And when I did the tensile strength test it was the same way almost a slight and linear higher force, but right at the end, this small spike.

Take a piece of balloon leftovers. start to stretch it, it is pretty smooth as you stretch it, but suddenly the resistance to stretch any further jumps greatly!

Joe WB9SBD

On 7/21/2020 8:33 PM, Jerry via groups.io wrote:
Correct.  I also did a test during a flight but couldn't find the data.

Jerry


On Tue, Jul 21, 2020 at 6:31 PM, Dennis Klipa - N8ERF
Jerry,

Thanks for the data.  Pretty small differential.  I assume that the graph shows the differential pressure vs time during which you added gas to the balloon at a more or less constant rate.  Is that correct?

Best Regards,
Dennis, N8ERF

On Tue, Jul 21, 2020, 9:19 PM Jerry via groups.io <jerrygable=yahoo.com@groups.io> wrote:
I did some experiments on the differential pressure on a balloon  This was a ground test on a fairly small latex balloon (100 Grams I believe)  but larger ones would be similar.  As you approach burst the diff. pressure rises. 

A good analogy is a rubber band.  There is a high force for the initial stretch of a new band then it drops off.  The pressure increases as you reach the breaking point.

The pressure doesn't change much on a balloon so you have to be pretty accurate if you want to obtain float wit a latex balloon.  It has been done with a very low amount of lift gas.

I suspect a Mylar balloon would have a sharper curve since they don't stretch but I haven't done any burst experiments with those.


Inline image


Jerry Gable
Balloon Flight Prediction tools
http://www.s3research.com


On Tuesday, July 21, 2020, 6:05:54 PM MST, Joe WB9SBD <nss@...> wrote:


I did have these numbers, But it was a long time ago.

The numbers I got I did it by testing a piece of the envelope it's tensile strength, and doing the tons of math to learn what the pressure differential would be.

What was interesting was someone ( do not remember who) actually did flight(s) with a pressure sensor.
The neat part was my measured of material and the math calculations, the number I got was within like 5% of what they measured.

Joe WB9SBD

On 7/21/2020 7:39 PM, Dennis Klipa - N8ERF wrote:
I am curious.  Many of us have measured the atmospheric pressure versus altitude.  I have wanted to, but haven't, measured the pressure inside the latex balloon as it rises.  Has anyone measured the pressure differential (inside vs outside) of the latex balloon as a function of altitude?  How much difference are we talking about trying to control with this valve.  If the balloon were a fixed volume you could do the calculation, but the latex balloons are not.

Best Regards,
Dennis Klipa, N8ERF

On Tue, Jul 21, 2020, 8:23 PM Joe WB9SBD <nss@...> wrote:
It was a 1500 Kaymont balloon.

Knowing the pressure differential is extremely low. When I tested the ping pong ball, I know it leaked badly. The texture of the ball just would not give a good seal.

I went with the silicone on both the "O" ring and the ball.

I also went with a pressure of the spring, Actually a spring I just could not find a spring suitable.  So I used a left over strip of balloon latex, attached to the ball and to a acrylic shaft.

The shaft was rotated to tighten the tension on the ball and seal.

I made it as loose as possible,, just enough to make the seal, and I mean barely!

I was worried that motion would even break the seal. It was that slight.

Even as light as that was,  it was not light enough, the flight still had a standard flight profile with rise to burst altitude, and did still pop.

Joe WB9SBD

On 7/21/2020 3:41 PM, Hank Riley via groups.io wrote:
Joe, please tell us more.  

Latex or other envelope?  How did it work out for you?  Any special reason for trying this valve method out?  What altitude was reached?   How long did it remain in the air?
___________________________________________________________


On Sunday, July 19, 2020, 09:06:33 AM EDT, Joe wrote:

I did that once. But the ping pong ball surface is too textured and does not make a bubble tight seal. I did a silicone ball and o ring.





Jerry
 

The x axis is time.  It was just a relatively constant fill rate.


On Tue, Jul 21, 2020 at 6:35 PM, Hank Riley via groups.io
<n1ltv@...> wrote:
Jerry, what do the numbers along the x-axis mean?




On Tuesday, July 21, 2020, 09:19:54 PM EDT, Jerry wrote:

I did some experiments on the differential pressure on a balloon  This was a ground test on a fairly small latex balloon (100 Grams I believe)  but larger ones would be similar. 


Hank Riley
 

Jerry, what do the numbers along the x-axis mean?




On Tuesday, July 21, 2020, 09:19:54 PM EDT, Jerry wrote:

I did some experiments on the differential pressure on a balloon  This was a ground test on a fairly small latex balloon (100 Grams I believe)  but larger ones would be similar. 


Jerry
 

Correct.  I also did a test during a flight but couldn't find the data.

Jerry


On Tue, Jul 21, 2020 at 6:31 PM, Dennis Klipa - N8ERF
<klipadk@...> wrote:
Jerry,

Thanks for the data.  Pretty small differential.  I assume that the graph shows the differential pressure vs time during which you added gas to the balloon at a more or less constant rate.  Is that correct?

Best Regards,
Dennis, N8ERF

On Tue, Jul 21, 2020, 9:19 PM Jerry via groups.io <jerrygable=yahoo.com@groups.io> wrote:
I did some experiments on the differential pressure on a balloon  This was a ground test on a fairly small latex balloon (100 Grams I believe)  but larger ones would be similar.  As you approach burst the diff. pressure rises. 

A good analogy is a rubber band.  There is a high force for the initial stretch of a new band then it drops off.  The pressure increases as you reach the breaking point.

The pressure doesn't change much on a balloon so you have to be pretty accurate if you want to obtain float wit a latex balloon.  It has been done with a very low amount of lift gas.

I suspect a Mylar balloon would have a sharper curve since they don't stretch but I haven't done any burst experiments with those.


Inline image


Jerry Gable
Balloon Flight Prediction tools
http://www.s3research.com


On Tuesday, July 21, 2020, 6:05:54 PM MST, Joe WB9SBD <nss@...> wrote:


I did have these numbers, But it was a long time ago.

The numbers I got I did it by testing a piece of the envelope it's tensile strength, and doing the tons of math to learn what the pressure differential would be.

What was interesting was someone ( do not remember who) actually did flight(s) with a pressure sensor.
The neat part was my measured of material and the math calculations, the number I got was within like 5% of what they measured.

Joe WB9SBD

On 7/21/2020 7:39 PM, Dennis Klipa - N8ERF wrote:
I am curious.  Many of us have measured the atmospheric pressure versus altitude.  I have wanted to, but haven't, measured the pressure inside the latex balloon as it rises.  Has anyone measured the pressure differential (inside vs outside) of the latex balloon as a function of altitude?  How much difference are we talking about trying to control with this valve.  If the balloon were a fixed volume you could do the calculation, but the latex balloons are not.

Best Regards,
Dennis Klipa, N8ERF

On Tue, Jul 21, 2020, 8:23 PM Joe WB9SBD <nss@...> wrote:
It was a 1500 Kaymont balloon.

Knowing the pressure differential is extremely low. When I tested the ping pong ball, I know it leaked badly. The texture of the ball just would not give a good seal.

I went with the silicone on both the "O" ring and the ball.

I also went with a pressure of the spring, Actually a spring I just could not find a spring suitable.  So I used a left over strip of balloon latex, attached to the ball and to a acrylic shaft.

The shaft was rotated to tighten the tension on the ball and seal.

I made it as loose as possible,, just enough to make the seal, and I mean barely!

I was worried that motion would even break the seal. It was that slight.

Even as light as that was,  it was not light enough, the flight still had a standard flight profile with rise to burst altitude, and did still pop.

Joe WB9SBD

On 7/21/2020 3:41 PM, Hank Riley via groups.io wrote:
Joe, please tell us more.  

Latex or other envelope?  How did it work out for you?  Any special reason for trying this valve method out?  What altitude was reached?   How long did it remain in the air?
___________________________________________________________


On Sunday, July 19, 2020, 09:06:33 AM EDT, Joe wrote:

I did that once. But the ping pong ball surface is too textured and does not make a bubble tight seal. I did a silicone ball and o ring.




Dennis Klipa - N8ERF
 

Jerry,

Thanks for the data.  Pretty small differential.  I assume that the graph shows the differential pressure vs time during which you added gas to the balloon at a more or less constant rate.  Is that correct?

Best Regards,
Dennis, N8ERF

On Tue, Jul 21, 2020, 9:19 PM Jerry via groups.io <jerrygable=yahoo.com@groups.io> wrote:
I did some experiments on the differential pressure on a balloon  This was a ground test on a fairly small latex balloon (100 Grams I believe)  but larger ones would be similar.  As you approach burst the diff. pressure rises. 

A good analogy is a rubber band.  There is a high force for the initial stretch of a new band then it drops off.  The pressure increases as you reach the breaking point.

The pressure doesn't change much on a balloon so you have to be pretty accurate if you want to obtain float wit a latex balloon.  It has been done with a very low amount of lift gas.

I suspect a Mylar balloon would have a sharper curve since they don't stretch but I haven't done any burst experiments with those.





Jerry Gable
Balloon Flight Prediction tools
http://www.s3research.com


On Tuesday, July 21, 2020, 6:05:54 PM MST, Joe WB9SBD <nss@...> wrote:


I did have these numbers, But it was a long time ago.

The numbers I got I did it by testing a piece of the envelope it's tensile strength, and doing the tons of math to learn what the pressure differential would be.

What was interesting was someone ( do not remember who) actually did flight(s) with a pressure sensor.
The neat part was my measured of material and the math calculations, the number I got was within like 5% of what they measured.

Joe WB9SBD

On 7/21/2020 7:39 PM, Dennis Klipa - N8ERF wrote:
I am curious.  Many of us have measured the atmospheric pressure versus altitude.  I have wanted to, but haven't, measured the pressure inside the latex balloon as it rises.  Has anyone measured the pressure differential (inside vs outside) of the latex balloon as a function of altitude?  How much difference are we talking about trying to control with this valve.  If the balloon were a fixed volume you could do the calculation, but the latex balloons are not.

Best Regards,
Dennis Klipa, N8ERF

On Tue, Jul 21, 2020, 8:23 PM Joe WB9SBD <nss@...> wrote:
It was a 1500 Kaymont balloon.

Knowing the pressure differential is extremely low. When I tested the ping pong ball, I know it leaked badly. The texture of the ball just would not give a good seal.

I went with the silicone on both the "O" ring and the ball.

I also went with a pressure of the spring, Actually a spring I just could not find a spring suitable.  So I used a left over strip of balloon latex, attached to the ball and to a acrylic shaft.

The shaft was rotated to tighten the tension on the ball and seal.

I made it as loose as possible,, just enough to make the seal, and I mean barely!

I was worried that motion would even break the seal. It was that slight.

Even as light as that was,  it was not light enough, the flight still had a standard flight profile with rise to burst altitude, and did still pop.

Joe WB9SBD

On 7/21/2020 3:41 PM, Hank Riley via groups.io wrote:
Joe, please tell us more.  

Latex or other envelope?  How did it work out for you?  Any special reason for trying this valve method out?  What altitude was reached?   How long did it remain in the air?
___________________________________________________________


On Sunday, July 19, 2020, 09:06:33 AM EDT, Joe wrote:

I did that once. But the ping pong ball surface is too textured and does not make a bubble tight seal. I did a silicone ball and o ring.




Jerry
 

I did some experiments on the differential pressure on a balloon  This was a ground test on a fairly small latex balloon (100 Grams I believe)  but larger ones would be similar.  As you approach burst the diff. pressure rises. 

A good analogy is a rubber band.  There is a high force for the initial stretch of a new band then it drops off.  The pressure increases as you reach the breaking point.

The pressure doesn't change much on a balloon so you have to be pretty accurate if you want to obtain float wit a latex balloon.  It has been done with a very low amount of lift gas.

I suspect a Mylar balloon would have a sharper curve since they don't stretch but I haven't done any burst experiments with those.


Inline image


Jerry Gable
Balloon Flight Prediction tools
http://www.s3research.com


On Tuesday, July 21, 2020, 6:05:54 PM MST, Joe WB9SBD <nss@...> wrote:


I did have these numbers, But it was a long time ago.

The numbers I got I did it by testing a piece of the envelope it's tensile strength, and doing the tons of math to learn what the pressure differential would be.

What was interesting was someone ( do not remember who) actually did flight(s) with a pressure sensor.
The neat part was my measured of material and the math calculations, the number I got was within like 5% of what they measured.

Joe WB9SBD

On 7/21/2020 7:39 PM, Dennis Klipa - N8ERF wrote:
I am curious.  Many of us have measured the atmospheric pressure versus altitude.  I have wanted to, but haven't, measured the pressure inside the latex balloon as it rises.  Has anyone measured the pressure differential (inside vs outside) of the latex balloon as a function of altitude?  How much difference are we talking about trying to control with this valve.  If the balloon were a fixed volume you could do the calculation, but the latex balloons are not.

Best Regards,
Dennis Klipa, N8ERF

On Tue, Jul 21, 2020, 8:23 PM Joe WB9SBD <nss@...> wrote:
It was a 1500 Kaymont balloon.

Knowing the pressure differential is extremely low. When I tested the ping pong ball, I know it leaked badly. The texture of the ball just would not give a good seal.

I went with the silicone on both the "O" ring and the ball.

I also went with a pressure of the spring, Actually a spring I just could not find a spring suitable.  So I used a left over strip of balloon latex, attached to the ball and to a acrylic shaft.

The shaft was rotated to tighten the tension on the ball and seal.

I made it as loose as possible,, just enough to make the seal, and I mean barely!

I was worried that motion would even break the seal. It was that slight.

Even as light as that was,  it was not light enough, the flight still had a standard flight profile with rise to burst altitude, and did still pop.

Joe WB9SBD

On 7/21/2020 3:41 PM, Hank Riley via groups.io wrote:
Joe, please tell us more.  

Latex or other envelope?  How did it work out for you?  Any special reason for trying this valve method out?  What altitude was reached?   How long did it remain in the air?
___________________________________________________________


On Sunday, July 19, 2020, 09:06:33 AM EDT, Joe wrote:

I did that once. But the ping pong ball surface is too textured and does not make a bubble tight seal. I did a silicone ball and o ring.




Joe WB9SBD
 

I did have these numbers, But it was a long time ago.

The numbers I got I did it by testing a piece of the envelope it's tensile strength, and doing the tons of math to learn what the pressure differential would be.

What was interesting was someone ( do not remember who) actually did flight(s) with a pressure sensor.
The neat part was my measured of material and the math calculations, the number I got was within like 5% of what they measured.

Joe WB9SBD

On 7/21/2020 7:39 PM, Dennis Klipa - N8ERF wrote:
I am curious.  Many of us have measured the atmospheric pressure versus altitude.  I have wanted to, but haven't, measured the pressure inside the latex balloon as it rises.  Has anyone measured the pressure differential (inside vs outside) of the latex balloon as a function of altitude?  How much difference are we talking about trying to control with this valve.  If the balloon were a fixed volume you could do the calculation, but the latex balloons are not.

Best Regards,
Dennis Klipa, N8ERF

On Tue, Jul 21, 2020, 8:23 PM Joe WB9SBD <nss@...> wrote:
It was a 1500 Kaymont balloon.

Knowing the pressure differential is extremely low. When I tested the ping pong ball, I know it leaked badly. The texture of the ball just would not give a good seal.

I went with the silicone on both the "O" ring and the ball.

I also went with a pressure of the spring, Actually a spring I just could not find a spring suitable.  So I used a left over strip of balloon latex, attached to the ball and to a acrylic shaft.

The shaft was rotated to tighten the tension on the ball and seal.

I made it as loose as possible,, just enough to make the seal, and I mean barely!

I was worried that motion would even break the seal. It was that slight.

Even as light as that was,  it was not light enough, the flight still had a standard flight profile with rise to burst altitude, and did still pop.

Joe WB9SBD

On 7/21/2020 3:41 PM, Hank Riley via groups.io wrote:
Joe, please tell us more.  

Latex or other envelope?  How did it work out for you?  Any special reason for trying this valve method out?  What altitude was reached?   How long did it remain in the air?
___________________________________________________________


On Sunday, July 19, 2020, 09:06:33 AM EDT, Joe wrote:

I did that once. But the ping pong ball surface is too textured and does not make a bubble tight seal. I did a silicone ball and o ring.




Dennis Klipa - N8ERF
 

I am curious.  Many of us have measured the atmospheric pressure versus altitude.  I have wanted to, but haven't, measured the pressure inside the latex balloon as it rises.  Has anyone measured the pressure differential (inside vs outside) of the latex balloon as a function of altitude?  How much difference are we talking about trying to control with this valve.  If the balloon were a fixed volume you could do the calculation, but the latex balloons are not.

Best Regards,
Dennis Klipa, N8ERF

On Tue, Jul 21, 2020, 8:23 PM Joe WB9SBD <nss@...> wrote:
It was a 1500 Kaymont balloon.

Knowing the pressure differential is extremely low. When I tested the ping pong ball, I know it leaked badly. The texture of the ball just would not give a good seal.

I went with the silicone on both the "O" ring and the ball.

I also went with a pressure of the spring, Actually a spring I just could not find a spring suitable.  So I used a left over strip of balloon latex, attached to the ball and to a acrylic shaft.

The shaft was rotated to tighten the tension on the ball and seal.

I made it as loose as possible,, just enough to make the seal, and I mean barely!

I was worried that motion would even break the seal. It was that slight.

Even as light as that was,  it was not light enough, the flight still had a standard flight profile with rise to burst altitude, and did still pop.

Joe WB9SBD

On 7/21/2020 3:41 PM, Hank Riley via groups.io wrote:
Joe, please tell us more.  

Latex or other envelope?  How did it work out for you?  Any special reason for trying this valve method out?  What altitude was reached?   How long did it remain in the air?
___________________________________________________________


On Sunday, July 19, 2020, 09:06:33 AM EDT, Joe wrote:

I did that once. But the ping pong ball surface is too textured and does not make a bubble tight seal. I did a silicone ball and o ring.



Joe WB9SBD
 

It was a 1500 Kaymont balloon.

Knowing the pressure differential is extremely low. When I tested the ping pong ball, I know it leaked badly. The texture of the ball just would not give a good seal.

I went with the silicone on both the "O" ring and the ball.

I also went with a pressure of the spring, Actually a spring I just could not find a spring suitable.  So I used a left over strip of balloon latex, attached to the ball and to a acrylic shaft.

The shaft was rotated to tighten the tension on the ball and seal.

I made it as loose as possible,, just enough to make the seal, and I mean barely!

I was worried that motion would even break the seal. It was that slight.

Even as light as that was,  it was not light enough, the flight still had a standard flight profile with rise to burst altitude, and did still pop.

Joe WB9SBD

On 7/21/2020 3:41 PM, Hank Riley via groups.io wrote:
Joe, please tell us more.  

Latex or other envelope?  How did it work out for you?  Any special reason for trying this valve method out?  What altitude was reached?   How long did it remain in the air?
___________________________________________________________


On Sunday, July 19, 2020, 09:06:33 AM EDT, Joe wrote:

I did that once. But the ping pong ball surface is too textured and does not make a bubble tight seal. I did a silicone ball and o ring.



Hank Riley
 

Joe, please tell us more.  

Latex or other envelope?  How did it work out for you?  Any special reason for trying this valve method out?  What altitude was reached?   How long did it remain in the air?
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On Sunday, July 19, 2020, 09:06:33 AM EDT, Joe wrote:

I did that once. But the ping pong ball surface is too textured and does not make a bubble tight seal. I did a silicone ball and o ring.