The amount of gas available is fixed and throttled.
Yes, it is usually throttled.
That raises the question, how do you explain, that in free expansion, there is no throttle and what about the Joule–Thomson effect (describing the temperature change of a real gas when it is forced through a valve), if there were a throttle?
Take, as example, a simply rocket for fireworks. Before igniting it, there is only the (solid) fuel and little to no gas.
After igniting the fuel, a large amount of gas (that obviously wasn't there before) is being expelled.
So how can the amount of gas be fixed?
The total volume of gas created by the chemical reaction can be calculated, but the amount over time (start to and of burn) is not fixed - it is increasing.
The vacuum is supposedly endless.
Supposedly ist is.
As explained before, this is one reason for Joule's Law not being applicable:
P
start*V
start=P
end*V
end will not work very well for V
end=∞.
They all failed to work initially.
Initially.
It is pretty normal for experiments to fail initially, e.g. due to mistakes in setup.
If they can be made to work reproducible, that's what counts.
It cannot be Joule's Law, when the requirements for Joule's Law to apply are not met.
Yes, it is.
Gas is being released into a vacuum.
No, it isn't as "releasing gas into a vacuum" is
not the only requirement of Joule's Law of Free Expansion.
The rockets do not move until there is adequate presence of pressure in the container.
Indeed, they do not move until they are started.
When the fuel burns, it creates hot gas, pressure rises, rocket starts moving.
Doesn't matter, if there's a vacuum or not.
I think you left something out...
What do you think of this quote?
“After compression it was heated, augmented by additional burning fuel(reported in the press to be kerosene), and finally discharged from the aft vent in a monstrous jet of energy pushing against the atmosphere.”
I think, it sounds rather colloquial (in contrast to scientific), so I can't really tell if this is a scientifically audited and verified statement or just a simplified description for a general audience.
Regardless ... so what?
If there is an atmosphere, the gas expelled from a jet engine or a rocket will obviously push against it.
The thrust, however, is not created by "pushing against the atmosphere", but by expelling the gas.
I didn't mention the exhausted gas pushing against the atmosphere, because it is not what creates thrust.
iC