Willliam,
Consider the basic principle that thrust = mass x velocity, but power
consumption is proportional to !/2MV2.
This means that while a small jet at twice the speed has the same thrust as
the larger jet at twice the area, the power consumption is four times
greater!
Big Slow Pumps!
For anyway near the same effectiveness the jet area needs to be around the
blade area of an oar.

Regards barry lawson

"William R. Watt" wrote in message
...

My main concern is the amount of propulsion that could be provided by foot
operated water pumps. I imagine a slow pump action, using, say 3" plastic
drain pipe for the pump body. I'll guess have to get out the college
physics
text and try some calcultations. Anything I should take into
consideration?

Hmmm... thrust - drag = mass X acceleration

Brian Whatcott

On Wed, 19 Oct 2005 07:04:02 +1000, "barry lawson"
wrote:

Willliam,
Consider the basic principle that thrust = mass x velocity, but power
consumption is proportional to !/2MV2.
This means that while a small jet at twice the speed has the same thrust as
the larger jet at twice the area, the power consumption is four times
greater!
Big Slow Pumps!
For anyway near the same effectiveness the jet area needs to be around the
blade area of an oar.

Regards barry lawson

"William R. Watt" wrote in message
...

My main concern is the amount of propulsion that could be provided by foot
operated water pumps. I imagine a slow pump action, using, say 3" plastic
drain pipe for the pump body. I'll guess have to get out the college
physics
text and try some calcultations. Anything I should take into
consideration?

Yeah, but the efficient process is the one most nearly reversible. Minimize
turbulence and velocity change.

Roger

http://home.earthlink.net/~derbyrm

"Brian Whatcott" wrote in message
...
Hmmm... thrust - drag = mass X acceleration

Brian Whatcott

On Wed, 19 Oct 2005 07:04:02 +1000, "barry lawson"
wrote:

Willliam,
Consider the basic principle that thrust = mass x velocity, but power
consumption is proportional to !/2MV2.
This means that while a small jet at twice the speed has the same thrust
as
the larger jet at twice the area, the power consumption is four times
greater!
Big Slow Pumps!
For anyway near the same effectiveness the jet area needs to be around the
blade area of an oar.

Regards barry lawson

"William R. Watt" wrote in message
...

My main concern is the amount of propulsion that could be provided by
foot
operated water pumps. I imagine a slow pump action, using, say 3"
plastic
drain pipe for the pump body. I'll guess have to get out the college
physics
text and try some calcultations. Anything I should take into
consideration?