|
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.
|
|
|
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
toggle quoted messageShow quoted text
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.
|
|
|
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.
|
|
|
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
toggle quoted messageShow quoted text
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.
|
|
|
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.
On Tuesday, July 21, 2020, 6:05:54 PM MST, Joe WB9SBD <nss@...> wrote:
I did have these numbers, But
it was a long time ago.
The numbers I got I did it by testing a piece of the envelope
it's tensile strength, and doing the tons of math to learn what
the pressure differential would be.
What was interesting was someone ( do not remember who) actually
did flight(s) with a pressure sensor.
The neat part was my measured of material and the math
calculations, the number I got was within like 5% of what they
measured.
Joe WB9SBD
On 7/21/2020 7:39 PM, Dennis Klipa -
N8ERF wrote:
I am curious. Many of us have measured the
atmospheric pressure versus altitude. I have wanted to, but
haven't, measured the pressure inside the latex balloon as it
rises. Has anyone measured the pressure differential (inside vs
outside) of the latex balloon as a function of altitude? How
much difference are we talking about trying to control with this
valve. If the balloon were a fixed volume you could do the
calculation, but the latex balloons are not.
Best Regards,
Dennis Klipa, N8ERF
On Tue, Jul 21, 2020, 8:23 PM
Joe WB9SBD < nss@...> wrote:
It was a 1500
Kaymont balloon.
Knowing the pressure differential is extremely low. When
I tested the ping pong ball, I know it leaked badly. The
texture of the ball just would not give a good seal.
I went with the silicone on both the "O" ring and the
ball.
I also went with a pressure of the spring, Actually a
spring I just could not find a spring suitable. So I
used a left over strip of balloon latex, attached to the
ball and to a acrylic shaft.
The shaft was rotated to tighten the tension on the ball
and seal.
I made it as loose as possible,, just enough to make the
seal, and I mean barely!
I was worried that motion would even break the seal. It
was that slight.
Even as light as that was, it was not light enough, the
flight still had a standard flight profile with rise to
burst altitude, and did still pop.
Joe WB9SBD
On 7/21/2020 3:41 PM, Hank Riley via groups.io wrote:
Joe,
please tell us more.
Latex
or other envelope? How did it work out for you?
Any special reason for trying this valve method
out? What altitude was reached? How long did it
remain in the air?
___________________________________________________________
On
Sunday, July 19, 2020, 09:06:33 AM EDT, Joe
wrote:
I did
that once. But the ping pong ball
surface is too textured and does not
make a bubble tight seal. I did a
silicone ball and o ring.
|
|
|
Jerry,
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
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.
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.
|
|
|
Correct. I also did a test during a flight but couldn't find the data.
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 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.
On Tuesday, July 21, 2020, 6:05:54 PM MST, Joe WB9SBD < nss@...> wrote:
I did have these numbers, But
it was a long time ago.
The numbers I got I did it by testing a piece of the envelope
it's tensile strength, and doing the tons of math to learn what
the pressure differential would be.
What was interesting was someone ( do not remember who) actually
did flight(s) with a pressure sensor.
The neat part was my measured of material and the math
calculations, the number I got was within like 5% of what they
measured.
Joe WB9SBD
On 7/21/2020 7:39 PM, Dennis Klipa -
N8ERF wrote:
I am curious. Many of us have measured the
atmospheric pressure versus altitude. I have wanted to, but
haven't, measured the pressure inside the latex balloon as it
rises. Has anyone measured the pressure differential (inside vs
outside) of the latex balloon as a function of altitude? How
much difference are we talking about trying to control with this
valve. If the balloon were a fixed volume you could do the
calculation, but the latex balloons are not.
Best Regards,
Dennis Klipa, N8ERF
On Tue, Jul 21, 2020, 8:23 PM
Joe WB9SBD < nss@...> wrote:
It was a 1500
Kaymont balloon.
Knowing the pressure differential is extremely low. When
I tested the ping pong ball, I know it leaked badly. The
texture of the ball just would not give a good seal.
I went with the silicone on both the "O" ring and the
ball.
I also went with a pressure of the spring, Actually a
spring I just could not find a spring suitable. So I
used a left over strip of balloon latex, attached to the
ball and to a acrylic shaft.
The shaft was rotated to tighten the tension on the ball
and seal.
I made it as loose as possible,, just enough to make the
seal, and I mean barely!
I was worried that motion would even break the seal. It
was that slight.
Even as light as that was, it was not light enough, the
flight still had a standard flight profile with rise to
burst altitude, and did still pop.
Joe WB9SBD
On 7/21/2020 3:41 PM, Hank Riley via groups.io wrote:
Joe,
please tell us more.
Latex
or other envelope? How did it work out for you?
Any special reason for trying this valve method
out? What altitude was reached? How long did it
remain in the air?
___________________________________________________________
On
Sunday, July 19, 2020, 09:06:33 AM EDT, Joe
wrote:
I did
that once. But the ping pong ball
surface is too textured and does not
make a bubble tight seal. I did a
silicone ball and o ring.
|
|
|
Jerry, what do the numbers along the x-axis mean?
On Tuesday, July 21, 2020, 09:19:54 PM EDT, Jerry wrote:
I did some experiments on the differential pressure on a balloon This was a ground test on a fairly small latex balloon (100 Grams I believe) but larger ones would be similar.
|
|
|
The x axis is time. It was just a relatively constant fill rate.
On Tue, Jul 21, 2020 at 6:35 PM, Hank Riley via groups.io <n1ltv@...> wrote:
Jerry, what do the numbers along the x-axis mean?
On Tuesday, July 21, 2020, 09:19:54 PM EDT, Jerry wrote:
I did some experiments on the differential pressure on a balloon This was a ground test on a fairly small latex balloon (100 Grams I believe) but larger ones would be similar.
|
|
|
I remember the data that
matched mine, was the actual flying flight.
There was a small but very detectable spike just before burst.
And when I did the tensile strength test it was the same way
almost a slight and linear higher force, but right at the end,
this small spike.
Take a piece of balloon leftovers. start to stretch it, it is
pretty smooth as you stretch it, but suddenly the resistance to
stretch any further jumps greatly!
Joe WB9SBD
toggle quoted messageShow quoted text
On 7/21/2020 8:33 PM, Jerry via
groups.io wrote:
Correct. I also did a test during a flight but couldn't find the
data.
Jerry
On Tue, Jul 21, 2020 at 6:31 PM, Dennis Klipa - N8ERF
Jerry,
Thanks for the data. Pretty small differential.
I assume that the graph shows the differential
pressure vs time during which you added gas to the
balloon at a more or less constant rate. Is that
correct?
Best Regards,
Dennis, N8ERF
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.
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.
|
|
|
Thanks for looking. I assume the data was consistent with the data you shared.
Dennis
Correct. I also did a test during a flight but couldn't find the data.
Jerry On Tue, Jul 21, 2020 at 6:31 PM, Dennis Klipa - N8ERF Jerry,
Thanks for the data. Pretty small differential. I assume that the graph shows the differential pressure vs time during which you added gas to the balloon at a more or less constant rate. Is that correct?
Best Regards, Dennis, N8ERF 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.
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.
|
|
|
Mark Conner N9XTN
I searched my Gmail archive and there are fragments of a discussion on this topic based on an ARBONET balloon flight in the summer of 2010 which may have measured this. There may even have been a GPSL presentation that summer on it. If you look in the archived messages from ~June-Sept 2010 you may find something.
GPSL 2010 was in Hutchinson KS.
73 de Mark N9XTN
On Tue, Jul 21, 2020 at 7:40 PM Dennis Klipa - N8ERF < klipadk@...> wrote: I am curious. Many of us have measured the atmospheric pressure versus altitude. I have wanted to, but haven't, measured the pressure inside the latex balloon as it rises. Has anyone measured the pressure differential (inside vs outside) of the latex balloon as a function of altitude? How much difference are we talking about trying to control with this valve. If the balloon were a fixed volume you could do the calculation, but the latex balloons are not.
Best Regards, Dennis Klipa, N8ERF
|
|
|
BASE_DePauw
I suggest reaching out to Michael K5NOT (ARBONET) who did the presentation at GPSL 2010.
Another investigator was James Flaten with his students at the University of Minnesota who shared their results at the Academic High Altitude Conference that same summer at Taylor University.
I cannot find copies of either presentation in my files tonight.
Howard, KC9QBN BASE_DePauw
On Tue, Jul 21, 2020 at 10:12 PM Mark Conner N9XTN < mconner1@...> wrote: I searched my Gmail archive and there are fragments of a discussion on this topic based on an ARBONET balloon flight in the summer of 2010 which may have measured this. There may even have been a GPSL presentation that summer on it. If you look in the archived messages from ~June-Sept 2010 you may find something.
GPSL 2010 was in Hutchinson KS.
73 de Mark N9XTN On Tue, Jul 21, 2020 at 7:40 PM Dennis Klipa - N8ERF < klipadk@...> wrote: I am curious. Many of us have measured the atmospheric pressure versus altitude. I have wanted to, but haven't, measured the pressure inside the latex balloon as it rises. Has anyone measured the pressure differential (inside vs outside) of the latex balloon as a function of altitude? How much difference are we talking about trying to control with this valve. If the balloon were a fixed volume you could do the calculation, but the latex balloons are not.
Best Regards, Dennis Klipa, N8ERF
-- Howard L. Brooks Professor of Physics and Astronomy 241 Julian Science and Mathematics Center DePauw University 2 E. Hanna Street Greencastle, IN 46135 hlbrooks@...
|
|
|
I managed to float a couple of 1200 and 1500 gram balloons by putting a PVC pipe with an end cap in the neck of the balloon and drilling a 1/16" hole in the end cap (two 1/16" holes were too much as were larger size drill holes). The ones with the single 1/16" hole all floated all night long over 100,000 feet or so.
- Bill WB8ELK
-----Original Message-----
From: BASE_DePauw <hlbrooks@...>
To: GPSL@groups.io
Sent: Tue, Jul 21, 2020 9:27 pm
Subject: Re: Superpressure balloon valve / was Re: [GPSL] K5NOT-11 WSPR Balloon Failure
I suggest reaching out to Michael K5NOT (ARBONET) who did the presentation at GPSL 2010.
Another investigator was James Flaten with his students at the University of Minnesota who shared their results at the Academic High Altitude Conference that same summer at Taylor University.
I cannot find copies of either presentation in my files tonight.
Howard, KC9QBN
BASE_DePauw
On Tue, Jul 21, 2020 at 10:12 PM Mark Conner N9XTN < mconner1@...> wrote:
I searched my Gmail archive and there are fragments of a discussion on this topic based on an ARBONET balloon flight in the summer of 2010 which may have measured this. There may even have been a GPSL presentation that summer on it. If you look in the archived messages from ~June-Sept 2010 you may find something.
GPSL 2010 was in Hutchinson KS.
73 de Mark N9XTN
On Tue, Jul 21, 2020 at 7:40 PM Dennis Klipa - N8ERF < klipadk@...> wrote:
I am curious. Many of us have measured the atmospheric pressure versus altitude. I have wanted to, but haven't, measured the pressure inside the latex balloon as it rises. Has anyone measured the pressure differential (inside vs outside) of the latex balloon as a function of altitude? How much difference are we talking about trying to control with this valve. If the balloon were a fixed volume you could do the calculation, but the latex balloons are not.
Best Regards,
Dennis Klipa, N8ERF
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Howard L. Brooks Professor of Physics and Astronomy 241 Julian Science and Mathematics Center DePauw University 2 E. Hanna Street Greencastle, IN 46135 hlbrooks@...
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