# Jet engine vs Rocket engine



## DaveH (Feb 17, 2011)

Heres a bit of fun  Question: I want to know the main difference between a Jet engine and a Rocket engine?

Your answer must be limited to 20 words or less. So comon all you clever clogs start thinking. 

I have an answer so lets see if we can get a match.

Dave


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## lazylathe (Feb 17, 2011)

Okay, here goes! Ek sal saam speel!

Reaction engines use jets of fluid to generate thrust.
Rocket engines use the propellants mass to generate propulsion.

18 words!!
How was that??

Andrew


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## Majorstrain (Feb 17, 2011)

Ok i'll give it a go. ;D

Jet engines are rocket engines with heaps of moving parts thrown in to lower the thrust and justify the cost.  :big:

_Smack on 20 words_

*or *

Jet engine failure - ka-ching, bang, thump, bang, bang, bang. Rocket engine failure - KA-BOOM, sizzle, silence. 8)

_15 words, 17 if you don't like hyphens_

You didn't say I had to be correct.

Cheers,
Phil


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## compspecial (Feb 17, 2011)

All the oxygen for combustion in rockets is contained in the fuel not sucked in


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## DaveH (Feb 17, 2011)

WOW! there sure are some clever people out there. But no cigar - quite close. ;D

Please try to keep your answer simple - for me :-*

keep on trucking

Dave


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## DaveH (Feb 17, 2011)

Phil

Must be the middle of the night there!

I like your answer ;D
Dave


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## Bill Gruby (Feb 17, 2011)

A Rocket is full thrust all the time a jet can be throttled.

 "Bill Gruby"


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## Majorstrain (Feb 17, 2011)

Not that late in Perth yet, 8pm.
Still at work though and a couple of more hours to go.
After a 6:30am start, my serious and sensible brain left for home hours ago, just the sad sense of humor left to keep me company now :

Cheers
Phil


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## DaveH (Feb 17, 2011)

Bill
Your answer is null and void. 20 words or less.
Just because you are a "grumpy clever so and so" does not mean you can change the rules 

Luv ya
Dave


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## DaveH (Feb 17, 2011)

I could change just one word in the question - but it might make it too obvious.

Boy O'boy isn't that a clue ;D

Dave


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## Majorstrain (Feb 17, 2011)

Ok, serious brain engaged.

A rocket engine has NO moving parts in the combustion area.

Dam, I've got a headache now. :'(

Phil


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## Bill Gruby (Feb 17, 2011)

DaveH  said:
			
		

> Bill
> Your answer is null and void. 20 words or less.
> Just because you are a "grumpy clever so and so" does not mean you can change the rules
> 
> ...



 HUH, there are only 13 words there. I edited it before you posted this. So I'm stayin Grumpy.  :bow:


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## DaveH (Feb 17, 2011)

Phil
Good answer, sadly no cigar - I'll send something for your headache.
A Ram jet would comply to your answer.

Dave


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## cl350rr (Feb 17, 2011)

they're spelled different

Randel


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## Majorstrain (Feb 17, 2011)

I'm with Randel, must be the right answer. :bow:

You got me with the Ram jet, I concede defeat.
Along the same lines of variation to the general rule, the ME163 Comet had complete throttle control.
http://homepage.ntlworld.com/andrew.walker6/komet/flight/flight2.htm

About half way down.


> The engines were completely throttleable. Acceleration at first seemed surprisingly slow. The aircraft was poised on small wheel blocks, and when you went from ground idle to full power, the dolly wheels would roll over the blocks, and it took a while to build up flight speed. Once airborne, you accelerated to speed for best climb.



Cheers,
Phil


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## DaveH (Feb 17, 2011)

Randel
WOW that is a cracking answer, where did you find that from?
Not the same as my answer but deserves special recognition.

So you can consider yourself the Third most cleverest person in the world. :bow:

After me and Bill of course ;D
Dave


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## ksouers (Feb 17, 2011)

I'll bite:

1) A rocket engine carries it's own oxidizer. I jet doesn't.

2) A rocket engine can operate in a vacuum, a jet can't.

Take your pick.


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## b.lindsey (Feb 17, 2011)

A jet engine has a central rotating shaft, a rocket engine doesn't

Bill


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## DaveH (Feb 17, 2011)

Time for a clue.

In the question change the word main to obvious.

.........the main obvious diff .......

Dave


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## cl350rr (Feb 17, 2011)

DaveH  said:
			
		

> Randel
> WOW that is a cracking answer, where did you find that from?
> Not the same as my answer but deserves special recognition.
> 
> ...



Wow, I'm up from 55th! I got the answer from wikapedia by the way...


a jet has moving parts a rocket does not

a jet takes in air a rocket makes it's own


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## DaveH (Feb 17, 2011)

Ksouers

Maxium 20 words.
Therefore your answer(s) are null and void.
And not really the answer I'm looking for, and every one will kick themselves when I reveal the answer.

The clue is the word obivous - easily seen
Dave


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## b.lindsey (Feb 17, 2011)

A jet has turbine blades.

Bill


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## ksouers (Feb 17, 2011)

Dave, there were two answers each less than 20 
Take out the word "engine" and you can combine both for less than 20 words.

Now you're being vague. You want a specific answer but aren't giving enough of a clue as to what you want. Sounding a bit like my wife :

I know it's all in fun, so don't take my response seriously


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## DaveH (Feb 17, 2011)

Ksouser
You are right it is only a bit of fun :

I'm not meaning to be vague.
The Clues are the words 'obvious' and 'whole'.

Your wife sounds like a really clever person just like me ;D

Does it help you should I give the answer?

Dave


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## ksouers (Feb 17, 2011)

Well, it's quite "obvious" to me that a jet engine needs to take in air, so I'm going with:

1) A rocket engine carries it's own oxidizer. I jet doesn't.


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## DaveH (Feb 17, 2011)

Kevin

So close - "take in air" change to "air in take" (w)hole - see the rocket see the jet - obvious -easily seen 

Dave


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## Majorstrain (Feb 17, 2011)

A jet engine has two holes, A rocket has only one.

Hows that?


Actually there is no difference between a jet engine and a rocket engine.
The rocket engine is just a sub set of the jet engine. According to 'ehow' anyway.




> Clarifying Definitions
> Formally, rocket engines are a subset of jet engines. But in standard terminology a "jet engine" refers to an aircraft engine wherein the combustion of fuel drives a turbofan or turbojet that provides vehicle, thrust as well as the energy needed by the engine to maintain the reaction. These jet engines require air for fuel combustion. Rocket engines also produce a 'jet' of exhaust that drives them forward, but require no moving parts in the combustion area and usually do not need air.



http://www.ehow.com/facts_5789785_difference-between-jet-rocket-engines.html

It's on the net, it must be true. Or was that the TV? I give up :

Off home now, Cheers
Phil


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## DaveH (Feb 17, 2011)

OK Here is the answer:
A Jet engine has 2 holes front and rear, Rocket engine just 1 at the rear. :bow: :bow: :bow:

It is a visual observation ;D

I'm just too good to be true!

So I'm still the cleverest person in the world 

Dave


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## Majorstrain (Feb 17, 2011)

I'll take the title of being the cleverest in the southern hemisphere.  :big: ;D :big:

Mind you, the answer had to be handed to me.

Cheers Dave,

Phil


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## Bill Gruby (Feb 17, 2011)

DaveH  said:
			
		

> OK Here is the answer:
> A Jet engine has 2 holes front and rear, Rocket engine just 1 at the rear. :bow: :bow: :bow:
> 
> It is a visual observation ;D
> ...


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## DaveH (Feb 17, 2011)

Bill Gruby

Well if you say so it must be right 

Dave


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## DaveH (Feb 17, 2011)

Just like to say what a great bunch of guys you all are. (except for 1 that is)
I feel privileged to belong to such a group.

Thank you all

Dave


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## Foozer (Feb 17, 2011)

Jet sucks, Rocket blows

4


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## DaveH (Feb 17, 2011)

Foozer,
Difficult to beat that answer.

Four words that could be a world record.

For your answer you are now considered the cleverest (honary) person in the world :bow: :bow: :bow:

Dave


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## Niels Abildgaard (Feb 17, 2011)

Jets are holier than rockets


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## MachineTom (Feb 17, 2011)

Dave your answer is WRONG. Rockets on the space shuttle have 2 outlets, the solid boosters have one each. The Russian soyute has 6 outlets, maybe 8. Solid fuel rockets can be throttled like 25% of full power, liquid fueled rockets can be throttled a large percentage.


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## DaveH (Feb 17, 2011)

MachineTom,

How can I be wrong  Bill said that I am the cleverest person in the world 

This is only a bit of fun - Like the teacher told you at school it is important to read the question carefully. The word 'engine' is paramount.

I didn't mention throttle!

Now we are still looking for the least cleverest person in the world ;D

Wondering if I should put your name down 

Dave


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## bearcar1 (Feb 17, 2011)

[quote  Question: I want to know the main difference between a Jet engine and a Rocket engine?
Dave 
[/quote]

Answer: Greater Terminal Velocity


BC1
Jim


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## DaveH (Feb 17, 2011)

Jim

You are not getting a prize for that, I have already given the answer ;D

Sorry but too late. 

Maybe next time

Dave


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## ChooChooMike (Feb 17, 2011)

Foozer  said:
			
		

> Jet sucks, Rocket blows
> 
> 4


 Rof} Jets blow too, out the back end where the thrust/exhaust goes


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## Foozer (Feb 17, 2011)

ChooChooMike  said:
			
		

> Rof} Jets blow too, out the back end where the thrust/exhaust goes



Could put it as a past president who blew a lot of hot air but never inhaled :

Robert


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## Captain Jerry (Feb 17, 2011)

The obvious difference between 2 holes and one hole is:


* ONE HOLE!*


Jerry


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## Cedge (Feb 17, 2011)

One sucks and blows, the other one just blows.
Nah... I really didn't type that......(grin)

Steve


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## dammvit (Nov 4, 2013)

A jet engines thrust can be change while running where as a rocket (solid fuel ) is fixed


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## dnalot (Nov 4, 2013)

The way they are spelled

Mark T


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## Tin Falcon (Nov 4, 2013)

Someone dug up an old thread
Tin


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## vederstein (Nov 4, 2013)

Rocket - Oxidizer on board
Jet - Oxidizer from air

Eight Words!!!


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## mcostello (Nov 5, 2013)

One is an engine and the other is a motor.


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## ConductorX (Nov 5, 2013)

MachineTom said:


> Dave your answer is WRONG. Rockets on the space shuttle have 2 outlets, the solid boosters have one each. The Russian soyute has 6 outlets, maybe 8. Solid fuel rockets can be throttled like 25% of full power, liquid fueled rockets can be throttled a large percentage.



Each "outlet" is a separate engine. 

Rocket engines can throttle and do have moving parts.  The liquid fuel pumps on the space shuttle can empty an Olympic size swimming pool in 10 seconds.

IMHO "G"


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