# 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 parameters that determine this speed?

• Welcome to Aviation.stackexchange saud. Nice first question. – DeltaLima Apr 26 '17 at 20:44

## 1 Answer

It's an aeroelastical phenomenon driven by pitching moment, torsion stiffness, and inertia of the wing. It's a classical spring-mass-damper problem: increased aerodynamic pitching moment causes torsion on the wing structure, which causes more pitching moment until the local airfoil AoA is such that the air flow separates. Torsion is counteracted by the wing torsional stiffness, thin wings have less torsional stiffness.

Parameters that determine flutter speed:

• Wing profile: aerodynamic $C_m$ and wing thickness
• Wing aspect ratio
• Number of jet engines mounted forward of the aeroelastic axis
• Wing sweep