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Re: AO40: status

The real problem with your theory is what would
keep the gas trapped long enough in any
compartment so that it could build pressure
and what would be the mechanism
for forcing its high speed expulsion at the
perimeter given that it can't build pressure to
any extent?

I have trouble visualizing it.  I have enough trouble
with the leak along the motor cooling jacket.
This is so near the Z spin axis that it would
have to be pretty energetic to spin up the
bird the delta between the normal spin up due
to decreasing moment of inertia (loss of mass)
and what we are now observing.  I just can't
make a mental image of any place in the
compartments where this could happen.


----- Original Message -----
From: "Bob Bruninga" <bruninga@usna.edu>
To: "Phil Karn" <karn@ka9q.net>
Cc: <maggie@voicenet.com>; <amsat-bb@AMSAT.Org>
Sent: Sunday, January 07, 2001 9:31 AM
Subject: Re: [amsat-bb] AO40: status

> On Sat, 6 Jan 2001, Phil Karn wrote:
> > Nope again. As the propellant drains outward, it gets accelerated by
> > the spacecraft body. This slows down the spin rate. As it dribbles off
> > the end, it continues in a straight line tangential to the point of
> > departure.
> Hummh...  You are thinking in terms of a liquid I think.  I am thinking in
> terms of a gas (I assume that all of the liquids instantly vaporize to a
> gas in the vacuum at the point of the leak (near the center of the
> spacecraft).  At that point, the gas is not in contact with the spacecraft
> and so it does not take away any angular momentum as it finds its way out
> of the bird through whatever holes it finds.
> Kind of like the fly flying around the cockpit of Lindberg's plane.  Does
> it add to the weight of his plane or not?
> But I guess it does take a finite period of time for any molecule of gas
> to get through the compartments and out, and by that time it has picked up
> the angular momentum of that compartment (no matter how small)...
> So then it must have all escaped near the center..
> > So if AO-40's spinup was caused by the simple movement of propellant
> > mass, it must have moved from the fuel tanks closer to the Z axis.
> Yep, we certainly agree on that point.
> de WB4APR@amsat.org, Bob
> See my APRS LIVE pages    http://web.usna.navy.mil/~bruninga/aprs.html
> See APRS SATELLITES       http://web.usna.navy.mil/~bruninga/astars.html
> See MIM/Mic-E/Mic-Lite    http://www.toad.net/~wclement/mim2.htm
> ----
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