Date   

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

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.




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

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.




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

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.




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

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.




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

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.



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

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.



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

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?
___________________________________________________________


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.


Re: Helium in a tank?

steve potter
 

I ran into that with a tank from oxarc, entire s cyl and it didn't lift off the ground and by the calculations we did the s cyl should of been a couple of extra cubic feet. It was great that a fellow ham invited lived about a quarter mile away from the launch site and had a tank at his house. He's not even into balloons but apparently we are all a bit different than the rest of the world.


On Mon, Jul 20, 2020, 11:40 AM K. Mark Caviezel via groups.io <kmcaviezel=yahoo.com@groups.io> wrote:
Caution:
I have encountered at least two industrial gas suppliers that offer lower cost 'balloon grade helium' which is not 99% or better helium.(!)  It is 30%-40% nitrogen.  The thought and rationale is that for normal party balloons, the inclusion of lower cost nitrogen allows persons to fully inflate party balloons, they'll float just fine and a bit cheaper than going with pure helium.  And this will very seriously screw up lift and burst calculations if you use it in a high altitude balloon. I've never used it.  But both times it was offered to me it took a surprising amount of dialog with the industrial gas guys to suss out that it is a 60-40 or 70-30% mix of helium and nitrogen. I don't necessarily fault the guys working at the industrial gas suppliers, they've undoubtedly been briefed that their balloon grade helium is the best stuff for filling balloons.  For 99+% of their customers that are filling balloons it probably is.


Re: Helium in a tank?

K. Mark Caviezel
 

Caution:
I have encountered at least two industrial gas suppliers that offer lower cost 'balloon grade helium' which is not 99% or better helium.(!)  It is 30%-40% nitrogen.  The thought and rationale is that for normal party balloons, the inclusion of lower cost nitrogen allows persons to fully inflate party balloons, they'll float just fine and a bit cheaper than going with pure helium.  And this will very seriously screw up lift and burst calculations if you use it in a high altitude balloon. I've never used it.  But both times it was offered to me it took a surprising amount of dialog with the industrial gas guys to suss out that it is a 60-40 or 70-30% mix of helium and nitrogen. I don't necessarily fault the guys working at the industrial gas suppliers, they've undoubtedly been briefed that their balloon grade helium is the best stuff for filling balloons.  For 99+% of their customers that are filling balloons it probably is.


Re: Helium in a tank?

Steve G8KHW / AJ4XE
 

You can get a good estimate of the purity of a gas by calculating the lift per unit volume. The typical "balloon helium" we get here in the UK is about 95-97% pure (the remaining 3 - 5% assumed to be air).  The lift per unit volume of balloon helium here is quite close to 1.0Kg/cu m (a rather lucky alignment).  If I have done my math right that's also almost exactly 1.0oz per cu ft.

If you know the weight of the balloon, the measured neck lift, and how much gas should have been in the tank you can calculate the lift per unit volume.

    Steve

On 20/07/2020 01:56, Larry wrote:
My payload went up at a slower rate that I had forecasted last time and I know I just got kind of lazy and sloppy.  But even with me adding weight to the payload and not accounting for it the helium should have caused the milk jug to go neutrally buoyant with the amount of gas that I got from the burst calculator.  We ended up emptying the bottle into the balloon which should have been 19 cu ft more than required.  I am guessing the burst calculator was correct.  Is there any reason for me to doubt the amount of helium in the tank as long as I verify the pressure is correct?  Should I ask the welding supply shop about the purity of their helium?

I am trying to be more careful this time

Larry
KJ6PBS

Virus-free. www.avg.com


Re: Helium in a tank?

Mark Conner N9XTN
 

I think helium from virtually any industrial gas supplier, even if labeled "balloon grade", is at least 99% purity, and often balloon grade is 99.99%.  Five nines is decent for most all industrial uses and six nines is towards laboratory grade.  You can ask if you got balloon grade or industrial grade, might even say on the invoice.  At Matheson (fka Linweld here), they put stickers on the balloon grade cylinders and the industrial grade ones aren't marked, but it's been several years since I got helium from them.

The small party balloon cylinders don't seem to have a fixed purity standard.  I read once that they sometimes blend with ~20% oxygen so that people who want to make Donald Duck voices with it don't end up asphyxiating themselves.  Don't bet your life on that though.

It's possible temperature effects might have affected your positive lift.  Other errors in the overall system probably are larger than the effect of having two vs five nines helium purity, unless you're doing flights where you measure lift in a few grams instead of a few pounds. 

73 de Mark N9XTN




On Sun, Jul 19, 2020 at 7:56 PM Larry <larry.phegley@...> wrote:
My payload went up at a slower rate that I had forecasted last time and I know I just got kind of lazy and sloppy.  But even with me adding weight to the payload and not accounting for it the helium should have caused the milk jug to go neutrally buoyant with the amount of gas that I got from the burst calculator.  We ended up emptying the bottle into the balloon which should have been 19 cu ft more than required.  I am guessing the burst calculator was correct.  Is there any reason for me to doubt the amount of helium in the tank as long as I verify the pressure is correct?  Should I ask the welding supply shop about the purity of their helium?

I am trying to be more careful this time

Larry
KJ6PBS


Helium in a tank?

Larry
 

My payload went up at a slower rate that I had forecasted last time and I know I just got kind of lazy and sloppy.  But even with me adding weight to the payload and not accounting for it the helium should have caused the milk jug to go neutrally buoyant with the amount of gas that I got from the burst calculator.  We ended up emptying the bottle into the balloon which should have been 19 cu ft more than required.  I am guessing the burst calculator was correct.  Is there any reason for me to doubt the amount of helium in the tank as long as I verify the pressure is correct?  Should I ask the welding supply shop about the purity of their helium?

I am trying to be more careful this time

Larry
KJ6PBS


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

Hank Riley
 

Looking at the cross section dimensioned drawing and the photograph, it's pretty certain the tetroon was filled through an internally threaded port. After removing the fill tube from the port, the calibrated pressure release valve was threaded into the same port using the  narrow, OD-threaded valve nipple, thus sealing the balloon.

This method allows for a casual (not requiring precision to reach a given equilibrium altitude) and "overfilled" (compared to a valveless flight) inflation of the tetroon.
The overfilling would of course result in a faster ascent.

So the equilibrium height would be determined by the valve release setting, not by a precisely measured amount of fill (as measured by gas volume delivered, or indirectly by the value of free lift produced at the launch site).


On Saturday, July 18, 2020, 11:44:33 PM EDT, James Ewen  wrote:

Is this valve to be used for filling, or venting?

It sounds like the intent was to allow for over fill for rapid ascent, and then release pressure at altitude. 


Re: K5NOT-11 WSPR Balloon Failure

Joe WB9SBD
 

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.

Even that getting the right spring tension at these tiny tiny pressure differentials and yet tight enough to get a seal is extremely hard to do.

Joe WB9SBD

On 7/18/2020 6:05 PM, Jerry via groups.io wrote:
Below is the image from the document Steve was referring to.

Someone that flies the picos, does a simple valve sound like something that might work?  It might make attaching the payload difficult.





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


On Saturday, July 18, 2020, 12:01:33 PM MST, Steve G8KHW / AJ4XE <steve@...> wrote:


Looks like that link does not work - search for the paper "Characteristics and Performance of Three Low-Cost Superpressure Balloon (Tetroon) Systems "

    Steve

On 18/07/2020 19:40, Steve G8KHW / AJ4XE wrote:

See the ping-pong valve described here:

    https://tinyurl.com/y5ukveyb

see fig 4

    Steve


On 18/07/2020 18:53, Jerry via groups.io wrote:
It seems like over inflation is a common problem.  Could we come up with a simple (and light) pressure releif valve that is inseted in the fill tube?  Maybe something that could be 3d printed.  You could also use overfill for a faster initial climb.  It might save a lot of balloons. 

Jerry


On Sat, Jul 18, 2020 at 10:31 AM, Michael
<mw@...> wrote:
Hi All,

I plotted the ascent and unexpected descent of the GPSL K5NOT-11 WSPR balloon I sent up. It was a WSPR Skytracker and SBS-13 balloon of which I had trouble sealing - the sealing unit recommended was not available and an equivalent unit melted the neck right off. The equivalent unit was likely defective and too hot. I had eventually sealed the neck and folded it up like we do with latex balloons. I felt it was probably OK to fly. However, after a short time at 43,000 ft float level the balloon came back down. I assumed the premature descent to be caused from where I sealed it.

However, something about the descent did not make sense. If the leak was at the bottom - at the seal, I would expect the balloon to descend some portion and then somewhat stabilize at a fair altitude as the helium would want to stay at the top of the envelope and not flow down and out at the filling neck. Instead it descended all the way on a very linear line. I now highly suspect the leak actually was a pinhole or larger that developed in flight at or near the top of the envelope as a very under-inflated envelope with positive buoyancy took the payload aloft. The balloon was filled to 7 grams of positive lift.

According to the ascent table provided by Scientific Balloons - who makes the SBS-13, 5-8gr of lift is the sweet spot. I measured the lift in several different ways and confirmed 7 gr lift. However, based on the table also provided by Scientific Balloons, the 7gr of lift should result in less than 1.3 meters of ascent rate. When I calculated the time from launch to float I came up with 1.77 meters / second ascent rate which does not agree with the 1.3 meters targeted, but rather reflects over 10 gr but less than 12 gr of free lift which is too much.

What I learned from premature descent of the K5NOT-11 balloon via the NTSB (North Texas Squirrely Balloon) analysis:
  • Free lift was most likely the culprit causing an over pressure envelope failure at the top of the envelope and not caused by a bad seal at the neck. The free lift was measured with a 0.1gr repeatable accuracy, but does not match up with the tables provided by Scientific Balloons, so an error / discrepancy / calibration issue crept in here in some manner.
  • Even though the sealer was a bear, it eventually sealed - and folding and taping probably was good as extra insurance.
  • When you seal one of these balloons, try sealing on the very end of the neck first to prove the seal process before sealing where you actually want the seal.
  • Science can be fun until your hope of achievement is overwhelmed by the realization of complete failure.
--Michael


Virus-free. www.avg.com


Re: K5NOT-11 WSPR Balloon Failure

Steve G8KHW / AJ4XE
 

The latter (rapid ascent and gas release at the desired altitude) . 

Another idea in the paper is a lift balloon - where the superpressure balloon is filled to just the correct amount on the ground and hauled up a latex balloon and released at the correct altitude.

    Steve G8KHW/AJ4XE

On 19/07/2020 04:44, James Ewen VE6SRV wrote:
Is this valve to be used for filling, or venting?

It sounds like the intent was to allow for over fill for rapid ascent, and then release pressure at altitude. 

James 
VE6SRV 

--
James
VE6SRV

Virus-free. www.avg.com


Re: K5NOT-11 WSPR Balloon Failure

James Ewen VE6SRV
 

Is this valve to be used for filling, or venting?

It sounds like the intent was to allow for over fill for rapid ascent, and then release pressure at altitude. 

James 
VE6SRV 

--
James
VE6SRV


Re: K5NOT-11 WSPR Balloon Failure

Jeff Ducklow
 

Seems like a elegant design solution, but not having pico flight experience, I’m wondering about the mass penalty for pico flight. 

 I'm estimating this value design to weigh between 7 and 10 grams.  I weighed out a  ping-pong ball, a lightweight spring, and a toothpick as a rod and came up with 3.1 grams.  I guessing that a printed nozzle would be at least 4  to 7 grams if not more.

I’d be interested in hearing from those with pico flight experience on practicality of adding the mass of a value, and if there are other issues to might bring?



On Jul 18, 2020, at 6:05 PM, Jerry via groups.io <jerrygable@...> wrote:

Below is the image from the document Steve was referring to.

Someone that flies the picos, does a simple valve sound like something that might work?  It might make attaching the payload difficult.


<1595113389798blob.jpg>


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


On Saturday, July 18, 2020, 12:01:33 PM MST, Steve G8KHW / AJ4XE <steve@...> wrote:


Looks like that link does not work - search for the paper "Characteristics and Performance of Three Low-Cost Superpressure Balloon (Tetroon) Systems "

    Steve

On 18/07/2020 19:40, Steve G8KHW / AJ4XE wrote:

See the ping-pong valve described here:

    https://tinyurl.com/y5ukveyb

see fig 4

    Steve


On 18/07/2020 18:53, Jerry via groups.io wrote:
It seems like over inflation is a common problem.  Could we come up with a simple (and light) pressure releif valve that is inseted in the fill tube?  Maybe something that could be 3d printed.  You could also use overfill for a faster initial climb.  It might save a lot of balloons. 

Jerry


On Sat, Jul 18, 2020 at 10:31 AM, Michael
<mw@...> wrote:
Hi All,

I plotted the ascent and unexpected descent of the GPSL K5NOT-11 WSPR balloon I sent up. It was a WSPR Skytracker and SBS-13 balloon of which I had trouble sealing - the sealing unit recommended was not available and an equivalent unit melted the neck right off. The equivalent unit was likely defective and too hot. I had eventually sealed the neck and folded it up like we do with latex balloons. I felt it was probably OK to fly. However, after a short time at 43,000 ft float level the balloon came back down. I assumed the premature descent to be caused from where I sealed it.

However, something about the descent did not make sense. If the leak was at the bottom - at the seal, I would expect the balloon to descend some portion and then somewhat stabilize at a fair altitude as the helium would want to stay at the top of the envelope and not flow down and out at the filling neck. Instead it descended all the way on a very linear line. I now highly suspect the leak actually was a pinhole or larger that developed in flight at or near the top of the envelope as a very under-inflated envelope with positive buoyancy took the payload aloft. The balloon was filled to 7 grams of positive lift.

According to the ascent table provided by Scientific Balloons - who makes the SBS-13, 5-8gr of lift is the sweet spot. I measured the lift in several different ways and confirmed 7 gr lift. However, based on the table also provided by Scientific Balloons, the 7gr of lift should result in less than 1.3 meters of ascent rate. When I calculated the time from launch to float I came up with 1.77 meters / second ascent rate which does not agree with the 1.3 meters targeted, but rather reflects over 10 gr but less than 12 gr of free lift which is too much.

What I learned from premature descent of the K5NOT-11 balloon via the NTSB (North Texas Squirrely Balloon) analysis:
  • Free lift was most likely the culprit causing an over pressure envelope failure at the top of the envelope and not caused by a bad seal at the neck. The free lift was measured with a 0.1gr repeatable accuracy, but does not match up with the tables provided by Scientific Balloons, so an error / discrepancy / calibration issue crept in here in some manner.
  • Even though the sealer was a bear, it eventually sealed - and folding and taping probably was good as extra insurance.
  • When you seal one of these balloons, try sealing on the very end of the neck first to prove the seal process before sealing where you actually want the seal.
  • Science can be fun until your hope of achievement is overwhelmed by the realization of complete failure.
--Michael


Virus-free. www.avg.com
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Re: K5NOT-11 WSPR Balloon Failure

Jerry
 

Below is the image from the document Steve was referring to.

Someone that flies the picos, does a simple valve sound like something that might work?  It might make attaching the payload difficult.


Inline image


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


On Saturday, July 18, 2020, 12:01:33 PM MST, Steve G8KHW / AJ4XE <steve@...> wrote:


Looks like that link does not work - search for the paper "Characteristics and Performance of Three Low-Cost Superpressure Balloon (Tetroon) Systems "

    Steve

On 18/07/2020 19:40, Steve G8KHW / AJ4XE wrote:

See the ping-pong valve described here:

    https://tinyurl.com/y5ukveyb

see fig 4

    Steve


On 18/07/2020 18:53, Jerry via groups.io wrote:
It seems like over inflation is a common problem.  Could we come up with a simple (and light) pressure releif valve that is inseted in the fill tube?  Maybe something that could be 3d printed.  You could also use overfill for a faster initial climb.  It might save a lot of balloons. 

Jerry


On Sat, Jul 18, 2020 at 10:31 AM, Michael
<mw@...> wrote:
Hi All,

I plotted the ascent and unexpected descent of the GPSL K5NOT-11 WSPR balloon I sent up. It was a WSPR Skytracker and SBS-13 balloon of which I had trouble sealing - the sealing unit recommended was not available and an equivalent unit melted the neck right off. The equivalent unit was likely defective and too hot. I had eventually sealed the neck and folded it up like we do with latex balloons. I felt it was probably OK to fly. However, after a short time at 43,000 ft float level the balloon came back down. I assumed the premature descent to be caused from where I sealed it.

However, something about the descent did not make sense. If the leak was at the bottom - at the seal, I would expect the balloon to descend some portion and then somewhat stabilize at a fair altitude as the helium would want to stay at the top of the envelope and not flow down and out at the filling neck. Instead it descended all the way on a very linear line. I now highly suspect the leak actually was a pinhole or larger that developed in flight at or near the top of the envelope as a very under-inflated envelope with positive buoyancy took the payload aloft. The balloon was filled to 7 grams of positive lift.

According to the ascent table provided by Scientific Balloons - who makes the SBS-13, 5-8gr of lift is the sweet spot. I measured the lift in several different ways and confirmed 7 gr lift. However, based on the table also provided by Scientific Balloons, the 7gr of lift should result in less than 1.3 meters of ascent rate. When I calculated the time from launch to float I came up with 1.77 meters / second ascent rate which does not agree with the 1.3 meters targeted, but rather reflects over 10 gr but less than 12 gr of free lift which is too much.

What I learned from premature descent of the K5NOT-11 balloon via the NTSB (North Texas Squirrely Balloon) analysis:
  • Free lift was most likely the culprit causing an over pressure envelope failure at the top of the envelope and not caused by a bad seal at the neck. The free lift was measured with a 0.1gr repeatable accuracy, but does not match up with the tables provided by Scientific Balloons, so an error / discrepancy / calibration issue crept in here in some manner.
  • Even though the sealer was a bear, it eventually sealed - and folding and taping probably was good as extra insurance.
  • When you seal one of these balloons, try sealing on the very end of the neck first to prove the seal process before sealing where you actually want the seal.
  • Science can be fun until your hope of achievement is overwhelmed by the realization of complete failure.
--Michael


Virus-free. www.avg.com


Update on GPSL videos

Mark Conner N9XTN
 

We're in the final stages of having the videos ready on the "GPSL Live" channel at YouTube.  Some are available now, and more will be coming soon.  Thanks to Jim Emmert for editing the Zoom videos into neat packages.


We will also be making the slides available, stand by for those details.

73 de Mark N9XTN


Re: K5NOT-11 WSPR Balloon Failure

Steve G8KHW / AJ4XE
 

Looks like that link does not work - search for the paper "Characteristics and Performance of Three Low-Cost Superpressure Balloon (Tetroon) Systems "

    Steve

On 18/07/2020 19:40, Steve G8KHW / AJ4XE wrote:

See the ping-pong valve described here:

    https://tinyurl.com/y5ukveyb

see fig 4

    Steve


On 18/07/2020 18:53, Jerry via groups.io wrote:
It seems like over inflation is a common problem.  Could we come up with a simple (and light) pressure releif valve that is inseted in the fill tube?  Maybe something that could be 3d printed.  You could also use overfill for a faster initial climb.  It might save a lot of balloons. 

Jerry


On Sat, Jul 18, 2020 at 10:31 AM, Michael
<mw@...> wrote:
Hi All,

I plotted the ascent and unexpected descent of the GPSL K5NOT-11 WSPR balloon I sent up. It was a WSPR Skytracker and SBS-13 balloon of which I had trouble sealing - the sealing unit recommended was not available and an equivalent unit melted the neck right off. The equivalent unit was likely defective and too hot. I had eventually sealed the neck and folded it up like we do with latex balloons. I felt it was probably OK to fly. However, after a short time at 43,000 ft float level the balloon came back down. I assumed the premature descent to be caused from where I sealed it.

However, something about the descent did not make sense. If the leak was at the bottom - at the seal, I would expect the balloon to descend some portion and then somewhat stabilize at a fair altitude as the helium would want to stay at the top of the envelope and not flow down and out at the filling neck. Instead it descended all the way on a very linear line. I now highly suspect the leak actually was a pinhole or larger that developed in flight at or near the top of the envelope as a very under-inflated envelope with positive buoyancy took the payload aloft. The balloon was filled to 7 grams of positive lift.

According to the ascent table provided by Scientific Balloons - who makes the SBS-13, 5-8gr of lift is the sweet spot. I measured the lift in several different ways and confirmed 7 gr lift. However, based on the table also provided by Scientific Balloons, the 7gr of lift should result in less than 1.3 meters of ascent rate. When I calculated the time from launch to float I came up with 1.77 meters / second ascent rate which does not agree with the 1.3 meters targeted, but rather reflects over 10 gr but less than 12 gr of free lift which is too much.

What I learned from premature descent of the K5NOT-11 balloon via the NTSB (North Texas Squirrely Balloon) analysis:
  • Free lift was most likely the culprit causing an over pressure envelope failure at the top of the envelope and not caused by a bad seal at the neck. The free lift was measured with a 0.1gr repeatable accuracy, but does not match up with the tables provided by Scientific Balloons, so an error / discrepancy / calibration issue crept in here in some manner.
  • Even though the sealer was a bear, it eventually sealed - and folding and taping probably was good as extra insurance.
  • When you seal one of these balloons, try sealing on the very end of the neck first to prove the seal process before sealing where you actually want the seal.
  • Science can be fun until your hope of achievement is overwhelmed by the realization of complete failure.
--Michael


Virus-free. www.avg.com

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