Fin Flutter Frequency

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camacd
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Fin Flutter Frequency

Postby camacd » Fri May 26, 2017 3:21 pm

Hi All

I'm considering a design for a high speed 29mm MD rocket, and I'm curious about the science of fin flutter. Can someone recommend a source of info?

What velocities is it likely to occur? I'd assume transonic velocities would be worst.

I can do a modal analysis of the design using FEM, and was wondering if anyone has any insight into the typical exciting frequencies that might be experienced? I would be aiming to make the lowest natural frequency significantly greater than the exciting frequency.

Regards
Cam
"He who says it can't be done is liable to be interrupted by somebody doing it". - My Mum

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CATO
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Re: Fin Flutter Frequency

Postby CATO » Fri May 26, 2017 4:38 pm

"In thrust we trust"

AMRS 21 L3 RSO
TRA 07459 L3

Impulse:
2020: 00,000 Ns (0% Z)
Ns 19: 14,725; 18: 14,767; 17: 5,973; 16: 34,558; 15: 35,955; 14: 6,016; 13: 10,208
PB - Gorilla N2717WC, H: 10,260', S: M1.14

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OverTheTop
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Re: Fin Flutter Frequency

Postby OverTheTop » Fri May 26, 2017 6:23 pm

Here is something if you have the patience to research how to drive the package.

http://www.aerorocket.com/finsim.html

Very nice package, but if you drive it badly, remember the saying "Garbage in, garbage out." Refer to my signature below for further guidance :)
TRA #13430
L3
"Everybody's simulation model is guilty until proven innocent" (Thomas H. Lawrence 1994)

martymonsta
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Re: Fin Flutter Frequency

Postby martymonsta » Mon May 29, 2017 10:37 pm

OverTheTop wrote:Here is something if you have the patience to research how to drive the package.

http://www.aerorocket.com/finsim.html

Very nice package, but if you drive it badly, remember the saying "Garbage in, garbage out." Refer to my signature below for further guidance :)


+1, yeah I second this. Very easy to get to get very wrong and end up with very incorrect results. Also if you want to know what this app uses to make the calculations and really if you are using it you should know why it works. If I were you I'd search AEROELASTIC OPTIMIZATION OF SOUNDING ROCKET FINS.

camacd wrote:I'd assume transonic velocities would be worst.


Try not to assume, it doesn't help you in the long run and generally results in losses of time and money.
Many years ago the great British explorer George Mallory, who was to die on Mount Everest, was asked why did he want to climb it. He said, "Because it is there."
Well, space is there, and we're going to climb it

MARS #21
AMRS #41 L2/LCO/RSO/CO


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