|
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
|
|
|
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.
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
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
Looks like that link does not work - search for the paper
"Characteristics and Performance of Three Low-Cost Superpressure
Balloon (Tetroon) Systems "
Steve
toggle quoted messageShow quoted text
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
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
|
|
|
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.
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
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
|
|
|
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?
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.
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
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
|
|
|
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
|
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|
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
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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
toggle quoted messageShow quoted text
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.
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
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
|
|
|
