In article iw_cg.1156$No1.239@attbi_s71,
says...

"Ned Simmons" wrote in message
...
In article ,
says...
In article oxZcg.1087$No1.766@attbi_s71,
"Dave Lyon" wrote:


What does the assembly weigh and what is the burst pressure? If the
burst pressure is 300 psi and the disk is one inch in diameter, the
thrust at the moment of burst will be (Pi (0.5)^2)(300)=
(0.785)(300)=
236 pounds. The impulse (integrated thrust) will be proportional to
tank volume.

Anyway, this thrust is enough to make most compressors move.

Joe Gwinn

Wouldn't that thrust assume you were pushing against a stationary
object?
Would it decrease relative to the distance the "hole" was to the floor
(or
wall)?

Not quite, the jet stream of pressurized air needs nothing to press
against. Its thrust is independent of anything but the pressure
relationships in the vessel and the nozzle, in this case the tank and
hole. It'd have as much thrust with a vacuum surrounding it. 'tis how
rockets work.


There is a potentially strong surface effect that depends on the
distance to a stationary surface. This surface effect is in addition to
the "rocket" thrust. The rocket thrust is *not* equal to area x
pressure.

Ned Simmons


Oh, that computes a little better in my head.

How is the rocket thrust figured?


Now if I could do that I'd truly be a Rocket Scientist g.

If you want to slog thru the numbers this looks like a good start.
http://www.grc.nasa.gov/WWW/K-12/airplane/rktthsum.html

But it doesn't look like there's enough there to do a calculation based
on the pressure behind a nozzle without having data on the flow
characteristics of the specific nozzle. You can probably find data on a
sharp edged orifice (hole in the tank in this case) in a thermodynamics
text or website.

Ned Simmons