Nonzero AOA vs. NC, fin shape

Discussion in 'Mid Power Rocketry (MPR)' started by dhbarr, Jun 3, 2019.

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  1. Jun 3, 2019 #1

    dhbarr

    dhbarr

    dhbarr

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    All this hubbub about shooting toys into tornadoes actually got me thinking about subsonic weathercocking.

    Tubefins are known to be highly resistant against same while still being substantially overstable. This makes sense ( to me ), as whenever the bird is offangle quite a lot of tube is shielded from the stream.

    But what about regular flatfins? Here I would guess something elliptish like the Astron Sprint, rounded not airfoiled.

    For nosecones, elliptical again?

    What overall rocket shape can most safely resist the wind without the tried-and-true "just go way faster" method?
     
  2. Jun 3, 2019 #2

    Nytrunner

    Nytrunner

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    A tuber's fin section is round on all lateral approach. The air diverts around it and doesn't have as pronounced a weathercock effect.

    Flat fins (even ellipticals) are still presenting flat planes to the wind and will be susceptible to weathercocking.

    I think low aspect ratio (span/root) is the way to go, just be wary of going understable. Makes sense as flat fins produce stability by catching airflow whereas tuber's have a substantial drag effect
     
  3. Jun 4, 2019 #3

    dhbarr

    dhbarr

    dhbarr

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    Where's your gut on nosecone?
     
  4. Jun 4, 2019 #4

    Nytrunner

    Nytrunner

    Nytrunner

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    I think they're all round (unless they're square)
     

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