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VK3ABK > INFO 19.07.02 09:01l 57 Lines 2790 Bytes #999 (0) @ WW
BID : 30375_VK3VSW
Read: DB0FHN GUEST
Subj: BALLOON. MY ANSWER.
Path: DB0FHN<DB0ZWI<DB0HDF<DB0HOT<OK0PBX<OK0PHL<OK0PPR<OK0PPL<RZ6HXA<IK1ZNW<
7M3TJZ<ON0BEL<VK3TE<VK3SPB<VK3FRC<VK3VSW
Sent: 020719/0551Z @:VK3VSW.#WEV.VIC.AUS.OC #:30375 [Geelong] $:30375_VK3VSW
From: VK3ABK@VK3VSW.#WEV.VIC.AUS.OC
To : INFO@WW
Hello to all balloonists.
We have been investigating the reason for a balloon to rise in air.
And also to include the fact that a submarine (or any sealed vessel) rises
and/or sinks in water. This has caused a lot of us to THINK! And not to
mearly accept that something 'light' rises, and something 'heavy' sinks.
Henry PA7KK was first to comment, with a suggestion that gravity was
involved. Later I read a reply from Alan G0FUM, and his first paragraphs
caused me to say,' he's got it'! But then hot air and helium got in the
way. The helium in a balloon plays a supporting role. It is mainly there
to support the container. Likewise, any non-rigid airship. Certainly, the
relative density/mass factor is important and must be 'low'.
Gerard PE1OUD introduced 'displacement mass' and suggested an upward force.
We made progress there! Then Harry M1BYT dispensed with the helium gas and
used a vacuum instead. Good point, and eliminated weight to make a balloon
rise faster. All of this, only gets to the reason WHY a balloon rises.
Let's go back to the submarine because my argument fits both air and water.
As Alan G0FUM suggested, 'atmospheric pressure reduces the higher you go,
due to the gravitational pull of the earth.... Air has density therefore
weight/mass.' Exactly! And the same applies to water. This is the basis of
my theory of why a balloon (or submarine) rises or falls.
I came to the conclusion that it is the pressure differential acting on the
exterior of a lighter-than-air helium filled balloon that made it rise.
And with a sealed container in water, being lighter than it's displacement,
to use a nautical term!' it also rises. Filling and blowing tanks enables
the submariner to control his situation.
Yes, Gerard, I did 'do the math' but it's not too difficult to 'imagine' in
say 10km of air or water, the pressure varies from a maximum at the bottom,
to zero at the top. This is where the container of Henry PA7KK, and the ship
of Gerard PE1OUD, stops and then floats if the water mass displaced is equal
to the mass of the container. Isaac Newton's law of equal and opposite forces
is confirmed. Pressure difference would be proportional to size and 'pushes'
the balloon/submarine up.
One other point that I mentioned, and haven't come to a conclusion, is what
would be the effect in a space ship, where gravity is minimum, and even more
serious, I doubt that there would be a pressure gradient. Many years ago,
in a science class, we did an experiment which showed that in a vessel, air
exerts pressure equally in all directions. Any space travellers about!?
I think this should answer my original question: providing I got it right!
73, and thanks for the interesting bulletins.
Dick. VK3ABK.
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