Fin Resonance

Seyhun Gültekin · Aug 20, 2019

Hello everyone we preparing our national model rocket competition in Turkey (aka Teknofest).Our rocket will finish soon but we consider about fin resonance due to motor ignition.Fins are made %100 carbon fiber.Anybody reasearch that resonance and what we should do for minimize resonance ? (ı add fin photo for our rocket)

Nytrunner · Aug 20, 2019

How fast will you be flying?

And is that a picture of a single fin? It looks very thick. I wouldn't expect it to flutter (the effect of resonance) until very high speeds.

Seyhun Gültekin · Aug 20, 2019

Nytrunner said:
How fast will you be flying?

And is that a picture of a single fin? It looks very thick. I wouldn't expect it to flutter (the effect of resonance) until very high speeds.

thanks for your answer we will fly under 1 mach ( apprx 0.5 mach)

mccordmw · Aug 20, 2019

Carbon fiber
Looks like a really short span
Mach 0.5

Unless your fins are paper thin, that's not going to flutter.

UhClem · Aug 20, 2019

NACA TN 4197 on fin flutter.

manixFan · Aug 20, 2019

Also see:

"How To Calculate Fin Flutter Speed"

https://www.apogeerockets.com/education/downloads/Newsletter291.pdf

also:

https://sites.google.com/site/chrisflaniganrocketry/Home/research-and-development

Good info on doing the math on both sites.

Tony

Seyhun Gültekin · Aug 21, 2019

manixFan said:
Also see:

"How To Calculate Fin Flutter Speed"

https://www.apogeerockets.com/education/downloads/Newsletter291.pdf

also:

https://sites.google.com/site/chrisflaniganrocketry/Home/research-and-development

Good info on doing the math on both sites.

Tony

ı check your documents they are really good info thx so much, actually we think about %100 carbon fiber or composite sandvic for prevent flutter effect what you suggest for this two technique.

dhbarr · Aug 21, 2019

At 600kph with ( what appear to be ) solid Through-The-Wall carbon fiber fins you should have nothing to worry about.

I would at least round that leading edge though, as thick as those fins are they will produce quite a lot of drag.

Funkworks · Aug 21, 2019

Is anyone is actually equipped to measure or simulate resonant frequencies for model rockets?

dhbarr · Aug 21, 2019

Funkworks said:
Is anyone is actually equipped to measure or simulate resonant frequencies for model rockets?

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

Fin Resonance

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Fin Resonance

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