Topics

K5NOT-11 WSPR Balloon Failure


Michael
 

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


Jerry
 

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


Steve G8KHW / AJ4XE
 

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


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


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


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
<1595113389798blob.jpg>


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


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


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