Questions tagged [flutter]

A type of uncontrolled divergent oscillations in an aircraft's structure, typically encountered at excessively-high speeds or if the airframe's stiffness has been reduced by previous damage. Flutter is extremely dangerous, and can rapidly cause an aircraft to break apart in flight; it has caused many fatal accidents over the years.

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3
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2answers
123 views

Does every control surface need to have a counterweight?

Is it not a good idea to balance all control surfaces, no matter what they weigh? I am building a small plane, with small control surfaces. There are many of the same type of plane flying. Most have ...
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2answers
397 views

Why was the Electra uniquely vulnerable to whirl-mode flutter?

The Lockheed L-188 Electra, notoriously, suffered from early problems with whirl-mode flutter, which caused two Electras to break apart in flight in 1959 and 1960, forcing an expensive redesign of the ...
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1answer
215 views

What is the difference between flutter and vortex induced vibration?

During flutter, the airfoil oscillates with a large amplitude, which generates vortices at the wake. In vortex induced vibration (VIV) the oscillations of the airfoil are caused by the shedding of ...
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1answer
263 views

Is aerodynamic flutter speed dependent?

Is it possible for control surface flutter to occur at low Reynolds and low speed? If yes,why don't Ultralights have counter weights or tail sting mass to immune the control surfaces against flutter ...
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1answer
87 views

How do we choose a frequency range of interest for flutter prediction?

I'm trying to perform some flutter and dynamical (gust etc.) calculations with Nastran. It has been told to use a range up to 30 Hz for an aircraft I'm working with, but why the upper limit is so ...
8
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3answers
630 views

How can engine positioning affect flutter tendency?

I understand that moving the engines towards the wingtips would increase flutter tendency, but are there any other positioning options which could affect flutter? How about moving the engine ...
9
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4answers
7k views

How are aircraft wings protected against flutter - aerodynamic oscillations that can break bridges?

It's a well known fact bridges can break due to self-amplified oscillations creating excessive loads on their structure, by resonance (galop). It happens from time to time. The Tacoma-Narrows bridge ...
3
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1answer
281 views

What are the factors that determine the speed flutter appears on wings?

I'm doing a study on the flutter phenomenon of airplane wings. I'm interested in factors that influence wing stability, and how one can increase the speed where flutter starts. What are the ...
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1answer
89 views

May someone please suggest EHA design procedures for AFS?

Are usual electro-hydraulic actuator designs for aileron control employable for aeroelastic flutter suppression? If not, where can I find design procedures for this specific case?
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2answers
1k views

How was flutter mitigated in jets such as the F-15 and F-16?

As I understand it flutter was a serious problem for early jets, like the XF-104. Flutter can affect any of the extended members of an aircraft during high-speed flight, including the wings and the ...
6
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1answer
2k views

Why can not two modes coincide perfectly for some cases in Flutter phenomena?

I have a question about flutter phenomena. As you know, flutter occurs when two modes (for example, first mode and second mode) coincide (that is, after a specific velocity, the frequencies of two ...
8
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1answer
307 views

Where can I find nice animations of flutter? [closed]

Where can I find nice flutter animations/videos (other than YouTube) to add to a presentation without violating Copyright regulations ? It can either be for wings as well as blade arrays. Are you ...
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2answers
7k views

What causes aileron and elevator flutter?

This video shows a Hawker jet with the wing fluttering up and down like it's about to break. What can cause flutter like that? Can it actually cause a wing or stabilizer failure? How can flutter be ...