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Why buy new model rocket engines?

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  1. Feb 28, 2015 #1
    Hi I was wondering why are model rocket engines disposable after one use? Is it because it is more economically feasible to buy a new model rocket engine than to repair a used one because the process of using a model rocket engine always ruins it? Also, if it is the case that model rocket engines are ruined after one use, is it also the case with larger rockets? For example Falcon 9 or the Atlas-V, does this require companies and agencies such as SpaceX and NASA to rebuild or construct new rocket engines after each launch similar to model rockets? And if the previous answer is yes, are rocket engine rebuilds or reconstructions a primary cost factor for why rocket launches are so expensive?

    Sorry for the questions and I appreciate anyone answering them, I was just curious :)
     
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  3. Feb 28, 2015 #2

    Simon Bridge

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    Welcome to pf,
    the damage to the engines means that it cannot safely be reused if repared.
    i.e. you could, technically refuel a sky-rocket tube, and reuse it. Why is that not routinely done?
     
  4. Feb 28, 2015 #3

    jedishrfu

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    Welcome to PF!

    There are reloadable model rocket engines

    http://www.hobbylinc.com/reloadable-model-rocket-engine

    Real life rocket engines fall to earth or the ocean and get seriously damaged on impact or later through salt water. Any of these factors are enough to warrant using new rocket engines to insure a safer launch.
     
  5. Feb 28, 2015 #4

    SteamKing

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    The two Solid Rocket Boosters (SRB) attached to each Space Shuttle mission were designed to separate after their fuel was exhausted, after which a parachute was deployed from each booster so that the boosters could be recovered from the Atlantic by a specially equipped vessel. The boosters were then returned to shore and refueled and re-furbished for use on future missions.

    http://en.wikipedia.org/wiki/Space_Shuttle#Solid_rocket_boosters

    In order to be reused, things like model rocket engines or Solid Rocket Boosters must be designed for multiple uses, which usually means that each unit is heavier than a single-use item.
     
  6. Feb 28, 2015 #5
    The next best thing we have to get into space is either hypersonic propulsion (very far from practical) or RAM accelerators/rail guns. Neither technology is mature enough to launch anythign appreciable into space. So, we are stuck with inefficient rockets in the sense that they are very heavy and have a small capacity.
     
  7. Feb 28, 2015 #6

    Dotini

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    Model rocket motors were always intended to be low-cost, disposable, safely manufactured for one use by the Estes corporation. The model rocket itself is intended to be a recoverable and reusable item, made from paper and balsa. I have launched, successfully recovered and reused a 4-stage model rocket (4 'A' motors). The first 3 stages were "tumble" recovery, and the 4th by streamer. All my rockets and launches were governed by the safety code of the National Association of Rocketry, of which I was a member.
     
    Last edited: Feb 28, 2015
  8. Mar 1, 2015 #7

    jim hardy

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    Rocket fuel is closely related to explosives. You don't want kids experimenting with it.
    Model engines are made very carefully.

    See "October Sky" , it's about home made rockets. And it is a darn good movie.

    http://en.wikipedia.org/wiki/October_Sky
     
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