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On this list right hand to left hand adapters have been discussed and bought by several groups. There were even part numbers specified, IIRC. That way their tried-and-true helium regulators didn't go to waste when a lot of the groups switched to hydrogen.
Not too much money for those. Look on Ebay. All over the place.
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That $500 price is totally nutz!!!! I can't imagine what device they have in mind. Just for grins you might ask them for a catalog sheet, or a make and model number.
You can easily beat that $93 price by watching Ebay for regulators. I got a fancy two stage regulator made by Linde (no better brand) years ago on Ebay -- it's a real gem (something like $20 shipped!). Nice big gauges -- not midgets.
One stage regulation is enough, though. One or two stage makes a fairly big price difference if bought new. It is nice to have it variable. Fixed output is a little cheesy, especially for small balloons. ________________________________________________________________________________________
On Wed, Jul 29, 2020, 3:47 PM Larry wrote:
I keep having to ask you questions. Well I appreciate your help anyway. So we are trying to shift over to hydrogen and the local welding supply place wants $500 for a regulator. Yet I see this $93 dollar regulator on line.
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Yes, mine is adjustable. You definitely want that for pico balloons or a flow restrict or because they take so little gas.
toggle quoted messageShow quoted text
-------- Original message -------- From: "L. Paul Verhage KD4STH" <nearsys@...> Date: 7/29/20 3:56 PM (GMT-06:00) To: GPSL@groups.io Subject: Re: [GPSL] Hydrogen regulators? This one looks adjustable. I spent far less at my local welding shop for a regulator with fixed settings.
Are you asking for an adjustable regulator? I think mine is permanently set for 30 PSI exit (outlet?) pressure. I keep having to ask you questions. Well I appreciate your help anyway. So we are trying to shift over to hydrogen and the local welding supply place wants $500 for a regulator. Yet I see this $93 dollar regulator on line.
Why should I not spend $93 instead of $500?
Larry
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I'm no expert on regulators so I'm hesitant to give an opinion. If you can find reputable reviews for this brand, it should be just fine. Mine is a well known brand thst I bought on ebay that wasn't too expensive because it was used. I've also heard of people using a helium regulator with a fitting adaptor sot it thread into the hydrogen fitting. Here to I wouldn't want to be the guy to endorse that.
Rucs
-------- Original message -------- From: Larry <larry.phegley@...> Date: 7/29/20 3:47 PM (GMT-06:00) To: gpsl@groups.io Subject: [GPSL] Hydrogen regulators? I keep having to ask you questions. Well I appreciate your help anyway. So we are trying to shift over to hydrogen and the local welding supply place wants $500 for a regulator. Yet I see this $93 dollar regulator on line.
Why should I not spend $93 instead of $500?
Larry
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They key is for H2 is left
hand thread. AND even for safety the pressure it can take. that
one looks good in both cases.
NOW the one we have been using 30+ years of flights, been using
H2 from first flight every flight.
But ours was not specified for H@, but some other Gas.
the thing is tho the left thread and the pressure capability.
The NOT spec'ed H2 was given to us, so cost?
Joe WB9SBD
toggle quoted messageShow quoted text
On 7/29/2020 4:56 PM, L. Paul Verhage
KD4STH wrote:
This one looks adjustable. I spent far less at my
local welding shop for a regulator with fixed settings.
Are you asking for an adjustable regulator? I
think mine is permanently set for 30 PSI exit (outlet?)
pressure.
I keep having to ask you questions. Well I
appreciate your help anyway. So we are trying to shift
over to hydrogen and the local welding supply place wants
$500 for a regulator. Yet I see this $93 dollar regulator
on line.
Why should I not spend $93 instead of $500?
Larry
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This one looks adjustable. I spent far less at my local welding shop for a regulator with fixed settings.
Are you asking for an adjustable regulator? I think mine is permanently set for 30 PSI exit (outlet?) pressure.
I keep having to ask you questions. Well I appreciate your help anyway. So we are trying to shift over to hydrogen and the local welding supply place wants $500 for a regulator. Yet I see this $93 dollar regulator on line.
Why should I not spend $93 instead of $500?
Larry
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I keep having to ask you questions. Well I appreciate your help anyway. So we are trying to shift over to hydrogen and the local welding supply place wants $500 for a regulator. Yet I see this $93 dollar regulator on line.
Why should I not spend $93 instead of $500?
Larry
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Re: Streaming video from a balloon
Yes which video you may also want to call 
nick Cell 337 258 2527 Helping UL become a world Class Engineering and Educational School Disagree I Learn
From: GPSL@groups.io <GPSL@groups.io> On Behalf Of Larry
Sent: Tuesday, July 28, 2020 6:14 PM
To: gpsl@groups.io
Subject: [GPSL] Streaming video from a balloon Mike ... Could I ask you some questions off line about how you streamed the video?
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Streaming video from a balloon
Mike ... Could I ask you some questions off line about how you streamed the video?
Larry KJ6PBS
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Jayant Murthy
Hydrogen is the way to go. Avoid closed spaces and sparks! Jayant
On Thursday, July 23, 2020, 11:30:40 PM GMT+5:30, Larry <larry.phegley@...> wrote:
I called and he assured me it was pure helium. ??? I can't see another explanation why it didn't lift. Anyway after checking the cost of gas and the cost of conversion .... Hydrogen here we come
Larry
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.
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.
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I called and he assured me it was pure helium. ??? I can't see another explanation why it didn't lift. Anyway after checking the cost of gas and the cost of conversion .... Hydrogen here we come
Larry
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.
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.
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Re: Superpressure balloon valve / was Re: [GPSL] K5NOT-11 WSPR Balloon Failure
I managed to float a couple of 1200 and 1500 gram balloons by putting a PVC pipe with an end cap in the neck of the balloon and drilling a 1/16" hole in the end cap (two 1/16" holes were too much as were larger size drill holes). The ones with the single 1/16" hole all floated all night long over 100,000 feet or so.
- Bill WB8ELK
-----Original Message-----
From: BASE_DePauw <hlbrooks@...>
To: GPSL@groups.io
Sent: Tue, Jul 21, 2020 9:27 pm
Subject: Re: Superpressure balloon valve / was Re: [GPSL] K5NOT-11 WSPR Balloon Failure
I suggest reaching out to Michael K5NOT (ARBONET) who did the presentation at GPSL 2010.
Another investigator was James Flaten with his students at the University of Minnesota who shared their results at the Academic High Altitude Conference that same summer at Taylor University.
I cannot find copies of either presentation in my files tonight.
Howard, KC9QBN
BASE_DePauw
On Tue, Jul 21, 2020 at 10:12 PM Mark Conner N9XTN < mconner1@...> wrote:
I searched my Gmail archive and there are fragments of a discussion on this topic based on an ARBONET balloon flight in the summer of 2010 which may have measured this. There may even have been a GPSL presentation that summer on it. If you look in the archived messages from ~June-Sept 2010 you may find something.
GPSL 2010 was in Hutchinson KS.
73 de Mark N9XTN
On Tue, Jul 21, 2020 at 7:40 PM Dennis Klipa - N8ERF < klipadk@...> wrote:
I am curious. Many of us have measured the atmospheric pressure versus altitude. I have wanted to, but haven't, measured the pressure inside the latex balloon as it rises. Has anyone measured the pressure differential (inside vs outside) of the latex balloon as a function of altitude? How much difference are we talking about trying to control with this valve. If the balloon were a fixed volume you could do the calculation, but the latex balloons are not.
Best Regards,
Dennis Klipa, N8ERF
--
Howard L. Brooks Professor of Physics and Astronomy 241 Julian Science and Mathematics Center DePauw University 2 E. Hanna Street Greencastle, IN 46135 hlbrooks@...
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Re: Superpressure balloon valve / was Re: [GPSL] K5NOT-11 WSPR Balloon Failure
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@...
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Re: Superpressure balloon valve / was Re: [GPSL] K5NOT-11 WSPR Balloon Failure
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
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Re: Superpressure balloon valve / was Re: [GPSL] K5NOT-11 WSPR Balloon Failure
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.
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Re: Superpressure balloon valve / was Re: [GPSL] K5NOT-11 WSPR Balloon Failure
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.
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Re: Superpressure balloon valve / was Re: [GPSL] K5NOT-11 WSPR Balloon Failure
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.
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Re: Superpressure balloon valve / was Re: [GPSL] K5NOT-11 WSPR Balloon Failure
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.
|
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|
Re: Superpressure balloon valve / was Re: [GPSL] K5NOT-11 WSPR Balloon Failure
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.
|
|
|
Re: Superpressure balloon valve / was Re: [GPSL] K5NOT-11 WSPR Balloon Failure
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.
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