Rockets are reactive engines - always . They use the reactive force of thrust .
No argument with that; quote Wikipedia: "Thrust is a reaction force described quantitatively by Newton's third law. When a system expels or accelerates mass in one direction, the accelerated mass will cause a force of equal magnitude but opposite direction on that system."
"Expelling mass in one direction" (in this case gas produced by burning rocket fuel) works just fine in a vacuum. Why wouldn't?
The physical process of igniting rocket fuel with its own oxidizer does not happen in a vacuum .
First of all, burning rocket fuel is a chemical reaction.
And why wouldn't fuel ignite in a vacuum?
For something to ignite one needs needs: heat, fuel and an oxidizing agent (fire triangle)
And all of it is there in a rocket ...
No work would be done even if it did ignite .
Gases expanding into a vacuum are not forced or pushed - that would require a resistance to expansion or gas flow .
Whyever would "pushing" only work with resistance?
Simply arguing from common sense: If someone "pushes" you back, you don't get pushed back because there is "resistance behind you", but because he's pushing you from the front.
Force is not generate at its "target" but at its origin - that origin is within the rocket, regardless of atmosphere or vacuum outside.
There is no force produced anywhere . Hence there is no reaction - no reactive thrust to accelerate .
I have thoroughly addressed this - in my previous post and above. Gas goes one way (not freely, but forced) - rocket goes the other way. Action - reaction.
Hot gas expanding freely into the vacuum would merely raise the temperature since it cannot convert to kinetic energy. There is the conservation of energy .
Did you read my explanation, why free expansion does
not apply for this case, at all?
If you think it is wrong, please let me know why. If you cannot tell why it's wrong, it's probably right.
"It cannot convert" is an unproven claim and - at best - a misconception. The chemical reaction is "pumping serious kinetic energy" into the gas.
When the gas expands into the vacuum no conversion into kinetic energy is needed - it has happened long before.
Rockets do not work by conservation of momentum , ridiculous statement.
It sad you're now down to derogatives.
Conservation of momentum is not the wording I would have chosen, but in the end it's true.
See above ...
Initial momentum zero (or anything else, if the rocket is already moving).
Momentum of gas leaving the rocket one direction vs. equal momentum of rocket going the opposite direction. => conservation of momentum
iCare has not clarified anything.
Well. I really tried to - and personally I think I did a fairly good job (I'm biased of course ...
).
On the other hand I don't see any indication that you put any effort into reading and analyzing my clarification ...
Makes me wonder, if it's not a lack of clarification on my side, but a lack of understanding on your side?
All either of you two have to do is show the details of the repeatable scientific experiment that proves a rocket engine can produce thrust in a vacuum .
Actually ... no.
First of all, I really don't feel the need to prove anything to you - as mentioned before, I'm here to further my understanding of the subject.
If it does the same for you - great. If you'd rather not learn from this discussion - your choice, your loss.
Secondly, my line of argument is logical deduction.
I have have - at great length - described my reasoning why rocket engines do produce thrust in a vacuum and shown the errors in your reasoning why they wouldn't.
Now it is your turn ... prove me wrong in what I wrote or accept that you can't.
When you've done your part and we have the theory worked out, we may talk about experiments to confirm or rebut the theory.
iC