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High speed jets used in rocket engines

  1. May 13, 2005 #1
    Ok, so I feel really stupid asking this question, but I guess you've gotta start somewhere to reach somewhere, so here goes nothing:

    I have this report to write and the title of the report has got me a bit confused. The professor's asked me to "write and present a technical report abut high speed jets as used in rocket engines".

    Now, I'm a total novice in the area of jet/rocket propulsion. Whilst doing some research on the internet, I learnt that jet engines are different from rocket engines, in terms of where they get their oxidizer from.

    This is the part that's got me confused, if jet engines are different from rocket engines, then what does the professor mean when he asked about "high speed jets as used in rocket engines"?

    Or have I totally misunderstood the professor, and he is simply asking me to write about rocket engines, how they work, etc.?

    Your help would be appreciated.

  2. jcsd
  3. May 13, 2005 #2


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    "Jets" is a bit of a misnomer, but understandable. Your prof. is refering to the rocket engines.
  4. May 13, 2005 #3


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    IIRC, jets are normally 'air' breathing engines, i.e. the oxidizer (oxygen in air) is supplied through the front end through a diffuser section and perhaps facilitated by a compressor, passed to the combustion chamber, and the resulting combustion products are exhausted for propulsion - basically an open system.

    Some missiles like the Bomarc and Snark used jet engines. IIRC, Bomarc had 2 ramjets and solid rocket motor booster to get the missile to the speed where the ramjets kicked in.

    A rocket motor involves a closed system where the oxidizer (e.g. liquid oxygen) is injected with the liquid fuel into the combustion chamber, or in the case of a solid propellant - fuel and oxidizer are intimately mixed and the combustion takes place at one end of the solid fuel and progresses in a burn front, or in a central bore - as in the Shuttles SRB's.
  5. May 18, 2005 #4
    It seems kind of condesending to say but please don't take it that way, and it's not a stupid question if oyu don't know the answer.
    THe first thing I would do is go back to your professor and ask him to clarify what he wants for this report and don't let up untill you're clear about what he expects. Otherwise you may make an assumption and do a lot of work on a report that'll be nothing about what the professor wanted. :cry:

    My next suggestion would be to pick Fred's brain clean :smile:
    Sorry I can't be of much more help, the last report on jets and rockets I did was in HS and it was a very basic one about the histoy/developement of rocket and jet engines.

    Fred: aside from the closed/open system difference between these engines aren't there different design considerations to take into account for the exhaust outlets on rockets and jets?
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