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Help with model rocket

  1. Jan 18, 2015 #1
    I am trying to build a model rocket for a contest. It goes up as a rocket but comes down as a glider. Vertical takeoff. Does not jettison any parts. Should glide down in large slow graceful circles. Judged based on total hang time. I have been able to avoid a outright nose dive by putting the cp really close behind the cg, but haven't achieved a glide. Any suggestions?
     
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  3. Jan 18, 2015 #2

    DaveC426913

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    Wings? ;)
     
  4. Jan 18, 2015 #3
    Yes they are an option. I used a long flat balsa wood wing but the wood snapped a short distance from the body during liftoff
     
  5. Jan 18, 2015 #4

    DaveC426913

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    If you're looking to have it glide, wings are not an "option"; they are mandatory.

    (Well, I suppose alternately you could have a parachute.)
     
  6. Jan 19, 2015 #5
    parachute not allowed
     
  7. Jan 19, 2015 #6

    DaveC426913

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    How do you expect to achieve any glide if you are still considering wings as optional?
     
  8. Jan 19, 2015 #7

    phinds

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    To expand on what Dave said (which is certainly true) can you see a way to arrange wings so that they don't snap off at liftoff but DO have an effect on the way down? I see one immediate solution that I believe could be made to work
     
  9. Jan 22, 2015 #8
    You can launch whit rocket something like this (rocket propelled UAV) dependent on rockets useful payload mass:
    AIR_UAV_Skylark-I-LE_from_Below_lg.jpg

    Alternatively you can use servos ,larger wings and remote controller to control flight
    9b0413cc14dff51eacf87811b35456a9.jpg
     
  10. Jan 22, 2015 #9

    phinds

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    Violates the condition of vertical takeoff.
    Violates the condition of coming back like a glider.

    I realize you are being creative here, but you are not answering the question as asked. I have taken the requirements as being part of the problem to be solved.
     
  11. Jan 22, 2015 #10
    Can you design it so that the wings will fold up and deploy when the rocket is falling? I know that some rockets deploy a parachute with a small detonation, so maybe you can use that to forcibly deploy some wings.
     
  12. Jan 22, 2015 #11

    phinds

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    This is what I was trying to lead the OP to (the deployment, although not quite your method), rather than spoon-feeding him the solution, since spoon-feeding is frowned on here on PF.
     
  13. Jan 22, 2015 #12
    Sorry @phinds! I didn't catch what you were trying to do. I guess subtlety isn't my strong suit. I figured the real challenge would be to design the vehicle for a long hang time, not in coming up with mechanisms for deployment. To me, ideas are a dime a dozen, but implementation is going to be where Eliott will really have to stretch and think.
     
  14. Jan 22, 2015 #13

    phinds

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    Yeah, I sometimes get carried away too by my interest in a problem and coming up with a solution and forget that we're here to help folks figure out how to do that for themselves. I often have to bite my tongue, so to speak, so I know where you're coming from. And yes, you're right that implementation will be non-trivial but you DO have to figure out first just what it is that you want to implement and that's what I wanted to lead him to.
     
  15. Jan 22, 2015 #14
    Phinds- next I will try having them make shorter, and I guess tapered.
    Dave- I meant they are allowed
    Time- it's not allowed to change shape significantly
     
  16. Jan 23, 2015 #15

    phinds

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    Hm ... not sure that will do the job. I had in mind a variation on the reaper's suggestion ... wings that are unobtrusive at liftoff but spread out at apogee
     
  17. Jan 23, 2015 #16
    Aileron allowed ?
     
  18. Jan 23, 2015 #17

    Bystander

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    What is this? Something from a BOMARC missile design competition from the 50s? Hit the library for old "Jane's" and start looking at Snark, Matador, Bomarc, designs.
     
  19. Jan 23, 2015 #18
    Wings which fold out sounds like a good idea. Could also use swept wings as the stabilizers during launch configuration. Once at max altitude the swept wings could fold out (like on the F-14) into a more or less glider configuration. You will need a second set of stabilizers behind the main wing though for flight stability.
     
  20. Jan 24, 2015 #19
    Well, since I let the cat out of the bag, here's a US military adaptation of this kind of rocket/plane:

    -- watch 46:08-46:50
    -- for a more promotional video,

    You could do something along these lines.
     
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