On Thu, 2 Mar 2006, Russell McMahon wrote:

>> With any high speed pump the speed will be limited mostly by the low
>> pressure ducting and suction therein, I think. A rocket certainly needs
>> high speed liquid pumping (besides the pressure).
>
> Filling is not the major issue. You only need to be able to fill a chamber in 
> the same time it takes to empty it. This is an easy task in most cases. A 
> much lower power filling pump could be used but in rockets modest tank 
> pressurisation or even justv the "head" induced by acceleration are enough to 
> do the job. For simple low pressure plastic versions gravity feed alone can 
> suffice.

Huh ? Filling a chamber through a metering orifice from a low head and 
then emptying it through another metering orifice at much higher 
pressure does not sound like an easy way to get 50% duty cycle. Imho 
with pressure ratios above 1:10 getting this right may be even more 
interesting than making a crude turbo pump. Of course any interruption 
in fuel feed to the engine means flameout. No ?

Peter
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