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Re: Propellant fluid dynamics at zero-g



> on 1/9/01 2:58 AM, Ulf Kumm at ulf@symek.de wrote:
> 
> > As soon as the motor runs, the sat is accelerated and the fuel
> > will slosh to the 'bottom' of the tank, which is 90 degree apart
> > from the nozzle used while ignition.
> > 
> > So, I still wonder how it can be made sure that propellant flows
> > without any interruption until the tank is empty.
> 

Jon, NA9D replies:

> Wouldn't the fuel in a spinning spacecraft be pushed to the side walls of
> the fuel tank due to centrifugal forces?  In effect, the spinning motion
> creates an artificial gravity.  Correct?

I roughly calculated the centrifugal force (assuming 0.1 rev/s and 1 m radius)
to be 0.6 N/kg . The effect of acceleration (400 N thrust on a 400 kg mass)
is 1 N/kg, i.e. the same order of magnitude. 

If both forces are present, one vector points away from the spin axis, 
the other points to the 'bottom' of the sat, where the motor is.
The sum of the vectors will point in an angle of maybe 45 degree.
Still asking... Where are the nozzle(s) at the tanks?   73! Ulf, DK9SJ

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