Whistler?

Discussion in 'High Power Rocketry (HPR)' started by PBic, Apr 13, 2019.

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  1. Apr 13, 2019 #1

    PBic

    PBic

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    I know I’m not the 1st to try it, but I’m playing around with the idea of placing whistles on a 3” rocket. I have 3 HyperWhistles, claimed to be the world’s loudest, reminding me again how much I loathe utterly unverifiable marketing claims, but decided to try them out. They are very loud, but I don’t think they’re near the 142db claimed.

    Whistle121.jpg Whistle222.jpg

    They’re 79mm overall length, about 36mm in diameter, and weigh 22g. My first idea was to place them on the tips of the fins, with the “blow hole” ahead of the leading edge, catching as much clear air as possible.

    Whistler1.PNG

    After thinking about it for a bit, I visualized this configuration doing a long lazy arc in an unintended direction. In think at that distance from the thrust line there’s no way they’ll be balanced enough to fly straight. I may have attempted this on a B or C impulse scale, but I’ll be flying this on an H178, and believe the results could be catastrophic.

    Now I’m thinking about placing them aft and between the fins on the body. They should be close enough to the thrust centerline and balanced well enough to fly straight. Whether there’s enough air flow at the needed pressure to have any effect… I guess I’ll have to find out.

    Whistler2.PNG

    What are your thoughts?
     
  2. Apr 13, 2019 #2

    kuririn

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    Sounds like fun. I'm working on something similar using Nerf whistling darts to do a semi clone of the Estes Screamin' Mimi:
    http://www.oldrocketplans.com/estes/est2185/est2185.pdf
    But it's way down on my building pile queue so don't know when I'll be getting around to it. Good luck!
     
  3. Apr 13, 2019 #3

    GlenP

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    Cool idea!

    I wonder what these would sound like on a rocket...

    Screen Shot 2019-04-13 at 12.49.23 PM.png

    To capture more air and force it into the whistle, you could use a larger diameter tube fin, and put a transition/reducer like a funnel to force the air into the whistle mouth at the bottom of the tube fin.
     
  4. Apr 14, 2019 #4

    PBic

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    That's probably the approach I should have taken, but I always seem to fail on a larger scale. o_O
     
  5. Apr 14, 2019 #5

    PBic

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    I was thinking about that too Glen, but then thought I would be dropping the pressure at the entrance of the whistle. If I don't get the effect that I want, I may fashion a scoop or some such.
     
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  6. Apr 14, 2019 #6

    PBic

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  7. Apr 15, 2019 #7

    dhbarr

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    I keep thinking that unbolting a couple of harmonicas and embedding them in the fins would probably work pretty well.
     
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  8. Apr 15, 2019 #8

    kyle

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    I'm the furthest thing from an expert on anything, but I like your first idea the best. Essentially the whistles would be fin pods. When I first glanced at the screen shot of it, it reminded me of an Estes Trajector.

    At the fin tips the whistles should also be in clean air, if that matters.

    Try it on something lower than the H178 and see what happens.
     
  9. Apr 16, 2019 #9

    PBic

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    Honer Rocket3.jpg
    Great idea! Here just the one to start with.
     
  10. Apr 16, 2019 #10

    BABAR

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  11. Apr 16, 2019 #11

    aerostadt

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    Like BABAR I remember more than one TRF threads with no joy on whistler rockets. I tried it too without convincing results. I tried a whistle outside of a car window and it worked, but really couldn't get results with a rocket.
     
  12. Apr 16, 2019 #12

    Dipstick

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    It would probably be the coolest on a rocket coming in ballistic so you could hear the piercing scream get louder as it came lower...but that's not anyone's idea of a good day lol
     
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  13. Apr 16, 2019 #13

    GlenP

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    I wonder if one of those flush mounted Nerf whistles would work on a x-24 bug during the glide? Might even be able to throw test it.
    Could put one in place of the canopy.
     
  14. Apr 16, 2019 #14

    jqavins

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    If you file some length off the downwind end, it should detune the whistle. Take something like 3 percent off the length of one whistle, and twice that off another, then mount up all three. If they sound at all, it'll make one hell of a racket! (Every 5.9% is a half-tone on a musical scale.)
     
  15. Apr 16, 2019 #15

    kuririn

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    The whistling part of a Nerf dart is the orange head. It is sealed from the rest of the dart. So just cut off that part and glue to a body tube exposed to the air stream.
    Don't think a glider would be going fast enough to whistle, but I could be wrong. Needs testing.
    Also the whistle is most apparent from a dart approaching you, not so much from one moving away. So if you REALLY want to hear the rocket whistle...…….
    (Just kidding).
     
  16. Apr 16, 2019 #16

    GlenP

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    Have you seen an x-24 “glide” ? It is more like falling, with style. Might also work on the side of a Black Widow glide back booster?
     
  17. Apr 16, 2019 #17

    kuririn

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    Yup, I made a clone. And you're right, it fell more than glided. But the clay ballast on the bottom kept it in the horizontal upright position. One other thing, the ejection charge sounded like a shotgun blast. I think the "megaphone" effect of the design was to blame. Somebody thought I put a firecracker in there. Or did I?:rolleyes:
     
  18. Apr 16, 2019 #18

    jqavins

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    No, of course you didn't. Who would ever even think of doing that? ;)
     
  19. Apr 17, 2019 #19

    rscaletta

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    We made one with a Nerf whistle dart as the nosecone. You can’t really hear it on the way up at all.

    Here’s a launch video from last month, we launch the Nerf rocket about halfway through

     

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