On Wed, 1 Mar 2006, Russell McMahon wrote:

> 3. You could try "my" 'Pistonless Piston Pump. I invented this as a 
> rocket propellant pump some years ago and only subsequently found out 
> that Lockheed Martin had patented the idea about 4 years before that. 
> A version of this was independently invented by and being developed in 
> secret by Flometrics (see it at 
> http://www.flometrics.com/rockets/rocket_pump/rocketpump.htm) when I 
> caused them some consternation by publishing my design. They now have 
> numerous patents on various aspects. An idea which I have public 
> domained and which is *NOT* covered by the LM patent is to use a 
> single chamber pump. The LM patent is based on 3 or more chambers with 
> 2 being mentioned as a throw away at the very end. 2 chambers is fine. 
> If you wish, you can use 2 or more of public domain single chamber 
> pumps with a common controller running them in appropriate phase 
> relationship, when they look suspiciously like the patented version. 
> It so happens that one of the very first British patents (1750s?) was 
> for a mine pump that worked on the same principle - there is little 
> new under the sun.

Why is this good ? Here is the Savery engine:

http://www.egr.msu.edu/~lira/supp/steam/savery.htm

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). And why is such a 
design 'lighter' than a turbopump ? A 20hp turbo (automotive, built of 
common materials and not aerospace stuff) is smaller than a six-pack of 
beer and weighs under 4 kgs. How can a gas piston pump compete with it ?

Afaik gas pressurized fuel feed for rockets was abandoned since the 
1950's. No ?

Peter
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