Re: Superpressure balloon valve / was Re: [GPSL] K5NOT-11 WSPR Balloon Failure
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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.
Balloon Flight Prediction tools
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.
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.
Dennis Klipa, N8ERF
On Tue, Jul 21, 2020, 8:23 PM Joe WB9SBD <nss@...> wrote: