Cadman’s Hydrostatic Displacement Engine

[Cadman]

Hi Gyula,
That's impossible to say at this point, I haven't finished the 6". I will be very happy if the piston speed of this 6" bore & stroke engine could average 6" per second. More likely it will be quite a bit less since I am currently limited to 1.5" ID plumbing. I can say this much, it all depends on the flow velocity you can achieve. Large diameter plumbing, fluid rotation while filling and discharging the cylinder, large radius bends, and high flow valves will be just as important as in a high performance ICE. Maybe more important.

If it matters, what I have built up until now is a mock up using 4" PVC pipe, garden hoses, hand operated valves (vise grips and wood blocks) and weights. Just enough to verify the concept is valid.  A 4" is too small for any kind of power. The 6" under construction is for experiments, testing and development.

What I want eventually is a 14" bore or 12" square, 3 to 6" stroke, 4" ID plumbing, 60 cycles per minute, 2 cylinder engine with a crankshaft and flywheel. 

Regards,
Cadman

[Floor]

I know this is possible.  Haven't studied your PDF yet.
Congratulations, I hope.

        floor

[Grumage]

A quick and dirty evaluation.

All the sixes, in Imperial measurements.

Six Feet head of water.    2.6 PSI

Six inch diameter piston. 28.27 square inches multiplied by 2.6 equals 73.5 Pounds pressure.

Six inch stroke. Volume of displaced fluid ( water ) 169.17 Cubic Inches. Mass 2.78 Kg or 6.116 Pounds.

Taking Cadman's value of 20 Pounds for the power piston and displacer piston assembly we then add the 6.116 Pounds ( working fluid to be returned ) giving 26.116 Pounds total.

By subtracting the 26.116 from the input pressure of 73.5 pounds we have a net gain of 47.4 Pounds
( 21.5 Kg ) losses excluded.

That's " my " take on Cadman's presentation. Mathematics isn't my best area of expertise so please feel free to contradict.

It's the clever use of the " displacer " piston to transfer the working fluid back to the header tank, my hat is off to you Cadman.

I can think of several means of reducing the losses like simple sliding gates for the control valves and having several vertical tubes through the displacer that can be covered by a thin Rubber flap at the top.

Thanks again Cadman.

Cheers Graham.

[lancaIV]

https://web.archive.org/web/20070225160446/http://www.theverylastpageoftheinternet.com/
"MAIN MENUE": E. L. S. A. gravity mill

[Cadman]

A quick and dirty evaluation.

All the sixes, in Imperial measurements.

Six Feet head of water.    2.6 PSI

Six inch diameter piston. 28.27 square inches multiplied by 2.6 equals 73.5 Pounds pressure.

Six inch stroke. Volume of displaced fluid ( water ) 169.17 Cubic Inches. Mass 2.78 Kg or 6.116 Pounds.

Taking Cadman's value of 20 Pounds for the power piston and displacer piston assembly we then add the 6.116 Pounds ( working fluid to be returned ) giving 26.116 Pounds total.

By subtracting the 26.116 from the input pressure of 73.5 pounds we have a net gain of 47.4 Pounds
( 21.5 Kg ) losses excluded.

That's " my " take on Cadman's presentation. Mathematics isn't my best area of expertise so please feel free to contradict.

It's the clever use of the " displacer " piston to transfer the working fluid back to the header tank, my hat is off to you Cadman.

I can think of several means of reducing the losses like simple sliding gates for the control valves and having several vertical tubes through the displacer that can be covered by a thin Rubber flap at the top.

Thanks again Cadman.

Cheers Graham.

Thanks Graham, and hats off to Archemedies and Pascal too.
In my calculations, I doubled the displaced weight at BDC, half for the displaced liquid above the pressure piston and half for the liquid above the displacer piston. You're spot on about several vertical tubes. I am using four 0.75" tubes that almost exactly equals the area of my 1.5" plumbing, with a flat disk valve at the top.

https://web.archive.org/web/20070225160446/http://www.theverylastpageoftheinternet.com/
"MAIN MENUE": E. L. S. A. gravity mill

That isn't the same thing but I wonder how often this has been thought of before now. I suspect this engine fits into the 'forgotten technology' category.

Cadman