Is it a "rocket engine" or a "rocket motor?"

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EeebeeE

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Let's have some fun and debate semantics.

I believe it is an "engine." An engine requires heat to provide movement. A motor does not. An electric motor is propelled by electricity and magnetism. Heat is a byproduct, not a force used to propel. On the other hand, a car engine is propelled by heat causing an expansion in a cylinder that moves a piston. A steam engine and stirling engine are external combustion engines, both requiring heat to expand air or steam. A rocket engine requires heat to burn a fuel which causes increased pressure underneath the rocket propelling it forward. The rocket itself is the piston being moved upward.

What do you think?
 
Why didn't you just weigh in on one of the hundreds of threads already covering this? This had been questioned for decades and there is NO end result, (from what I gather) So having said that, call it what you like. Both apply.
 
Done to death...

Here's the proper usage in space program terminology--

A solid rocket is called a "motor", and a liquid rocket engine is called an "engine" because of the complex combustion cycles (in many cases), high parts count turbomachinery (in most cases), complex valving, and combustion chamber/nozzle and often nozzle extension construction, versus a solid motor which is basically a giant road flare with a nozzle... (more or less).

Nuf said...

Later! OL JR :)
 
Which is wrong, all due respect to Mr. Estes.

later! OL JR :)

PS... see what you've started!!!!

I've gotten better about not pilin' on but sometimes it just happens, ya know ? :blush: I guess it was a slow day for me too. And yes, ALL DUE RESPECT TO MR. ESTES IN CAPITAL LETTERS... EXCLAMATION POINT... END OF STORY!!! :wink:
 
This debate has been going on for a while.

View attachment 176578
Read that article, in which it argues that the device propelling a rocket is a rocket engine. Then read the article about the "Baka" bomb, in which the propulsive devices are labelled "rocket motors". :lol:

Time to bring out the old compromise solution, which is "whoosh generator". :D
 
I know this has been done to death, but an unstirred pot makes lousy soup. This is fun. ;) Thanks for playing along.

When I took physics in college, I recall several problems involving "heat engines." In those problems internal or external combustion did not matter. The engine had a heat cycle that created expansion, moving a piston down, followed by a cooling cycle that pulled the piston back up. In short all engines generally have pistons that are moved by heat.

Motors on the other hand are powered by an outside source that converts one form of energy to mechanical energy. Case in point, in your car, an engine powers your transmission which in turn applies force to the axles and tires. So your car's transmission is actually a motor that is powered by a heat engine. In diesel-electric trains, an engine powers a generator that supplies electricity to motors that run the wheels. Same principal.

By this definition, the entire rocket is an engine, not just the propellant. The propellant is the simply the heat source which drives the piston upward. The rocket is the piston. When propellant is expired, the rocket cools. There is no more expansion of gas to drive the piston upward, so it comes back down...unless it goes into orbit, and that complicates things. :facepalm:
 
Time to bring out the old compromise solution, which is "whoosh generator". :D

How about "whoosher-pusher"? Or more seriously, a "pyrodyne", whose greek roots mean it produces power from heat?
 
Webster's Definitions:
- Engine: a machine that changes energy (such as heat from burning fuel) into mechanical motion.
- Motor: a machine that produces motion or power for doing work.

Since there is no mechanical motion involved in rocketry, then it should be an engine.

But I also like whoosher-pusher.
 
Just be politically correct and call it a propulsion device... Or just name it by its designation...

Instead of "I loaded the motor" or "it needs a bigger engine", just say "I loaded the H410" or "it needs another grain of propellant"... :p
 
On the other hand, a car engine is propelled by heat causing an expansion in a cylinder that moves a piston.

Actually it's a series of explosions caused by spark to fuel that moves the pistons.
For me I don't any kind of explosion in my rockets except for ejection so for me I'll call them motors.:wink:

Why didn't you just weigh in on one of the hundreds of threads already covering this? This had been questioned for decades and there is NO end result, (from what I gather) So having said that, call it what you like. Both apply.

This goes to your point.

https://www.worldwidewords.org/articles/engine.htm
 
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However, an explosion is just a really fast burn, so theoretically...


:)


You could say that a rocket motor is a controlled slow explosion...
 
Webster's Definitions:
- Engine: a machine that changes energy (such as heat from burning fuel) into mechanical motion.

That's a bit specific. More generally, an engine is something that changes energy from one form to another - such as stored chemical energy to kinetic energy - like our rocket motors do.

A motor sets a vehicle in motion - like our rocket engines do.

-- Roger
 
However, an explosion is just a really fast burn, so theoretically...


:)


You could say that a rocket motor is a controlled slow explosion...

We spent about a decade and a hundred thousand dollars proving that the above isn't true. :)

-- Roger
 
If you were to read the arguments that won the ATFE lawsuit then, you would know the difference....
In order to detonate, or explode: the shock waves have to break a certain speeds.

Do some research rather than rehash what they dramatize on TV!




JD


However, an explosion is just a really fast burn, so theoretically...


:)


You could say that a rocket motor is a controlled slow explosion...
 
Let's have some fun and debate semantics.
An engine requires heat to provide movement.

What do you think?

Heat is a byproduct, and usually an unwanted one. Heat = wasted energy
In an internal combustion engine, it's the rapid expansion of gases that does the work. Same for a rocket motor/engine.
In fact, ICEs make good air compressors when slightly modified and operated in reverse.

The following comes from MIT, so it must be right. It lost me by the second sentence. :)

https://engineering.mit.edu/ask/what’s-difference-between-motor-and-engine
 
Car engine:
Combustion chambers: cylinder heads
they move the pistons which turns the crank shaft,
A motor doesn't need all that; it just goes.
No mechanical means necessary to move a rocket on solid fuel.

A liquid engine components are required to function: valves, pumps etc...

JD

That's a bit specific. More generally, an engine is something that changes energy from one form to another - such as stored chemical energy to kinetic energy - like our rocket motors do.

A motor sets a vehicle in motion - like our rocket engines do.

-- Roger
 
From Spark Notes online in reference to Heat Engine problems:

Heat Engines

A heat engine is a machine that converts heat into work. Heat engines are important not only because they come up on SAT II Physics, but also because a large number of the machines we use—most notably our cars—employ heat engines.

A heat engine operates by taking heat from a hot place, converting some of that heat into work, and dumping the rest in a cooler heat reservoir. For example, the engine of a car generates heat by combusting gasoline. Some of that heat drives pistons that make the car do work on the road, and some of that heat is dumped out the exhaust pipe.

Doesn't rocket fuel convert heat into work?
 
From Spark Notes online in reference to Heat Engine problems:

Heat Engines

A heat engine is a machine that converts heat into work. Heat engines are important not only because they come up on SAT II Physics, but also because a large number of the machines we use—most notably our cars—employ heat engines.

A heat engine operates by taking heat from a hot place, converting some of that heat into work


You might want to rethink that… If the above were true, then I could put an Internal combustion engine in a large oven and turn up the heat in the oven and expect work to be produced by the engine; which isn't true.
Examples of heat engines would be a refrigerator and to some extent, a diesel engine, as the heat in a diesel engine starts the combustion of the fuel which in turn causes work to be done.
 
Doesn't rocket fuel convert heat into work?

In a rocket motor, it's the expanding gasses that produce the work, heat is a byproduct of the reaction (combustion) of the fuel. I don't know if you remember the old "Coldpower" rockets, but they used freon as the "fuel". The " coldpower" motor was a tank of compressed freon, and when it was discharged out of the nozzle, the freon expanded which caused thrust. No heat involved.

I guess in a pure physics context, they would be considered "heat engines" as there is a temperature differential in all these devices, but it's the expansion of gas from a chemical reaction that does the work.
 
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