19
votes
Accepted
How are control surface problems in wings having high bending dealt with?
Flaps and ailerons are weak in bending and have multiple hinges along the span. Also, as you can see in the photo, the flaps are segmented which not only helps to optimize the deflection angle over ...
- 237k
6
votes
Accepted
Does flutter disappear above the flutter speed?
Flutter happens when elastic and aerodynamic frequencies converge. Normally, the elastic one is (almost) fixed and the aerodynamic one increases with flight speed. When speed increases further and the ...
- 237k
5
votes
Accepted
How can engine positioning affect flutter tendency?
To better understand what flutter is, see the structure as a mass-spring system like a spring pendulum that has a damper attached to it. The aerodynamic forces both make the spring stiffer and dampen ...
- 237k
5
votes
Do/why don't spaceplanes suffer from flutter?
Apologies for trying to offer an answer to a nearly three year old question, but I'm unable to resist this one.
The truth is that all spacecraft that operate (however briefly) in our atmosphere do ...
- 51
4
votes
Accepted
Combating flutter with mass distribution?
Do I understand correctly that with this approach, the wing will act similarly to the following model, where the motion is rather chaotic?
No, your combination of masses and springs will have several ...
- 237k
3
votes
What is the relationship between aspect ratio and divergence speed?
Because the wing has less torsional stiffness for a given area. This lets lower torsion moments overpower the ability of the wing to resist that torsion.
The torsional stiffness is proportional to ...
- 237k
3
votes
Accepted
What is the difference between flutter and vortex induced vibration?
Flutter and vortex induced vibrations (VIV) are both dynamic instabilities arising from the interaction of unsteady aerodynamic, inertial and elastic forces. They both extract energy from the air ...
- 156
2
votes
How do airliners with engines mounted on places other than wings suppress wing flutter?
Since flutter is a natural-frequency harmonics phenomenon, it's a matter of "tuning" the wing box structure with the required stiffness and damping to move its natural frequency range outside the ...
- 136k
2
votes
Do/why don't spaceplanes suffer from flutter?
Not Shuttle specific, but there are generally two ways to prevent flutter of a control surface; for a manually operated surface, you balance it to put the surface's CG at or slightly forward of its ...
- 136k
1
vote
Can a normally poorly handling airframe with high moments of inertia actually have superior flight dynamics under autonomous control?
The underlying assumption of your question seems to be that a higher control bandwidth always leads to better disturbance suppression. Since a higher control bandwidth is easier to achieve with low-...
- 13.7k
1
vote
How can engine positioning affect flutter tendency?
This is a very interesting question, with a very complicated answer!
The problem of Aero-Elasticity is not easy or simple to solve. The reason is, that the equations (or better the system of equations)...
- 1,547
1
vote
How do we choose a frequency range of interest for flutter prediction?
You might want to try reviewing MIL-A-8870C AIRPLANE STRENGTH AND RIGIDITY
VIBRATION, FLUTTER, AND DIVERGENCE. The CRJs were certified to this standard. Available here: http://everyspec.com/MIL-...
- 136k
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