Rverence
116613
1770
30
Flutter is a dangerous phenomenon encountered in flexible structures subjected to aerodynamic forces. This includes aircraft, buildings, telegraph wires, stop signs, and bridges. Flutter occurs as a result of interactions between aerodynamics, stiffness, and inertial forces on a structure - In a linear system, 'flutter point' is the point at which the structure is undergoing simple harmonic motion - zero net damping - and so any further decrease in net damping will result in a self-oscillation and eventual failure.
A NASA test using a Piper PA-38 , the plane is flown to a speed causing flutter in the tail & stops before its failure.
Full clip : https://www.youtube.com/watch?v=3mJ_CAR52h4
The widely seen Tacoma Narrows bridge failure caused by aeroelastic flutter due to high winds on 7th November 1940
Multiple videos for this on YT : eg https://www.youtube.com/watch?v=j-zczJXSxnw
A six-month old bridge over the Volga river sways in strong winds in Volgograd in Russia
Full clip : https://www.youtube.com/watch?v=AQT-t4HQmGo
Note: "Mr I DGAFecski"
Winds batter Seattle floating bridge in 2013
Full video: https://www.youtube.com/watch?v=tF9XLij-K6w
imostlymadethisup
The stealth fly just like a real bird. That's why it's stealth.
menchicutlets
Reminds me of the nervous feeling of looking out of the window during a flight and seeing how much parts of the wing flutter and twist x.x
overboard
you forgot this one:
DMorison
I'd've upvoted for "Mr I DGAFecski" alone, even if I hadn't been interested in the post ;-)
mdh5663
My dad watched the wings on a DC3 flap "like a gooney bird" his first time in an airplane.
grendelgetskilledinthend
Coming home from FRG in late 70’s I saw the same wing flapping on the 747 I was in. Unsettling experience but they’d break off otherwise.
CheeseborgarSoop
God damn, that's mildly terrifying.
Fershnickered
https://youtu.be/7_mccjAnCOk
fortunateson1969
This post was deeply unpleasant for me.
Hereliesmyexaccount
My aerodynamic force
Madraving
That made me nervous.
OmegaKamidake
I always love the guy's reaction when he first spots it. "Oh look a cat :D .. what the fuck a cat"
PianoMan2112
I saw this out of sequence and thought it jumped midair.
DarkerSavant
When I skate board down hill.
bdawg468
Loathe Lockheed Electra encountered a similar force. Aeroelastic whirl flutter. It similar to flutter but on a rotating structure.
beerz4yearz
oh god, used to have to drive over #5 even just a couple years ago... you could feel it wiggling side to side on even mild windy days
NarroNow
I thought it was some kind of new technology where the stealth bomber was flapping to fly
Vicissitude
Ah, the majestic sky pancake, flapping its way to freedom
gatharen
Flappybomber
KittensGivePaarthurnaxGas
I thought it was just happy its picture was being taken. Like a shy anime girl getting noticed by Senpai.
CloseupCaptionReaction
Heatseekers hate them.
riftventdweller
Shhhh! You know too much!
SpartanSamuel
How else can they get above 30 speed?
EvilKrikkit
Call in the 'thopters! Muad'dib is leading the fremen!
EBRisTheFastUSAMotorcycle
Yess!!!
Brainlord
from "Analysis: The Arrakeen Crisis" by Princess Irulan
HumanityIsTheAwkwardPrepubescentPhaseBetweenAnimalAndMachine
Long live the fighters!
Snarfalopogus
Always upvote Dune
NQA1
The flappening.
TheRealArminTamzarian
whosagodboy
Her hips says fuck me but her eyes says fuck you
AYYDunkins
whats the sauce?
pterodactylptime
Fenixred
Always upvote Galloping Gertie
yourmememanJake
Isn’t it awesome (and sometimes annoying) that this is simulated in Kerbal Space Program?
ErikTheMostViking
MrSpadey
Gzzzzzz
This is the full details http://dl.btc.pl/kamami_wa/hk_24474_2.pdf
thatwoodguy
The Tacoma Narrows was a problem called "Vortex Shedding" where alternating high/low pressure regions form and peel offnear the natural freq
DavidBrooker
Vortex induced vibration was not actually the cause of the collapse. It was flutter. This is remarkable, because Von Karman was on the 1/2
DavidBrooker
investigation committee, and he actually discovered VIV, so he was quick to think that was the cause. :P 2/2
laton
#4 is no one going to comment on the Russian dude walking across the bridge during that? Balls of steel
Ben1045
Your mom had just walked across the bridge (see the shaking), so he knew it was strong.
Rverence
Mr I DGAFecski - "I want Vodka"
ENCHANTMEN
If I knew it was safe I bet it would be fun to walk on
TheIndigoManticore
I've only ever seen it called "harmonic resonance", but still cool to see. Not that I like doing the math on it though (undergrad physics)
DavidBrooker
This is not resonance. In resonance, a set outside force causes a vibration, which the structure amplifies. In aeroelasticity, the 1/2
DavidBrooker
vibration of the structure also changes the forces on the body. These are far, far from the resonant modes of the structures. 2/2
TheIndigoManticore
Ah right. That makes sense. As I said, undergrad physics here so still learning. Thanks though!
Dedeurmetdebaard
mastermindelectric
I agree
notasocleverusername
IUseSmallBananas4Scale
(Insert Shaq shaking gif here)
QuicheAdvisor9
NotifweJammit
Kitteh Flutter results in an attack.
EvilKrikkit
The701
I can handle dancing like this.
MarcoPoloOnPollo
JARKB
Why does she look so pissed?
EvilKrikkit
I sent her a dicpic
jbcars4life
Never heard it called flutter ever. It's always been called natural frequency
DavidBrooker
They aren't the same thing.
jbcars4life
Harmonic resonance occurs where the acting force matches the objects natural frequency which causes the flutter
DavidBrooker
That's not accurate. For an object in torsion, like a wing, the governing equation looks something like: F=kα+bα'+mα", where α is twist. 1/n
DavidBrooker
You can compute the natural frequency from k, b, and m alone. Then, if F is driven at this frequency, you get resonance. That isn't what 2/n
DavidBrooker
you see above. Rather, in aeroelasticity, the force itself is also governed by twist. The equation more like 0=(k-πρu^2)α+(b-πρuc)α'+mα" 3/n
DavidBrooker
To be clear: you do not need an oscillating force to begin flutter. ANY non-zero force at the flutter speed causes spontaneous oscillation.
jbcars4life
I'll be honest I gave up after your first reply mainly because I don't care that much. My education ended at basic principles so once I 1/2)
jbcars4life
Come across an occasion I need to know more advanced principles I will use Google. The day my job deals with that I'm demanding a raise
mustang2733
In flight, what can a pilot do to right the plane?
OmenRider
Slow down, change altitude (to a flight level with 'smoother air'), etc.
GuW69
Increase load on the surface and/or decrease speed
mustang2733
I'm guessing that decrease speed is the common method since it is hard to put more weight on a flying plane, right?
SteevyT
Well, you can always jam the stick to some extreme, but the passengers might not like that.
mustang2733
Or love it depending on the type of plane youre in
Nathan7378
There is also the fact that jamming the stick back at high speeds will overload the airframe, and the stress will literally cause the 1/x
Nathan7378
airframe to break into pieces. This is why in upset recovery we level the wings before pulling out the the dive, because yanking the 2/x