T/F

Divergence only occurs when the AC is in front of the EA

Divergence is not affected by the CG position

Increasing bending stiffness increases divergence speed

Lowering torsional stiffness lowers divergence speed

Down rotation of a TE surface decreases lift

Down rotation of a TE surface creates a nose-up moment.

High speed ailerons generate a smaller twisting moment on the wing

A diagonal matrix operator implies the lack of coupling among the degrees of freedom

Compliance matrix is a synonym for stiffness matrix

A swept back wing section rotates nose-up when the wing bends downwards

Divergence dynamic pressure increases for positive sweep angles

All the eigenvalues of the elastic wing solving system go to zero at the same dynamic pressure

In most airplane wings, the tip is twisted nose-up wrt to the root

A periodic time response was assumed because of the absence of damping

For a free-free beam, the two boundary conditions are the tip are identical

In the beam eigenvectors, the deformation becomes more localized for increasing frequency

The Rayleigh-Ritz method is one of choice for very complex structures.

In the solution of the mode coalescence example we used the Rayleigh-Ritz method

Configuration-dependent force means that the force depends on the initial shape of the beam

The presence of a follower force modifies the stiffness and mass of the system

Frequency coalescence is a form of resonance

In an ascending plunging motion of airfoil, the angle of attack decreases

Pitching an airfoil nose-down creates an opposing nose-up pitching momen

In a classical flutter case, the torsional mode softens, and the bending mode hardens

Aerodynamics adds a diagonal contribution to stiffness matrix.

The circulation bound to the airfoil implies that the flow speed is higher on the pressure side than on the suction side

If an airplane is pitching, the angle of attack at its horizontal tail is affected by the pitch rate

If a gust changes instantaneously the angle of attack of the wing, the effect is felt immediately also at the horizontal tail.

Unsteady aerodynamic effects are prevalent at very low reduced frequencies.

The dynamic stall lift loop is more pronounced for large average angles of attack

Stall-induced flutter couples at least two elastic mode.

The U-g method neglects the structural damping

Spacing the first bending and torsional frequencies is not a good design practice, as long as flutter is concerned.

When the centre of gravity is forward the elastic axis, only static instabilities are present

Excitations by existing control surfaces are limited in bandwidth.

If n is the scale factor and n_t the time factor, speed scales are n*n_t.

And Mach scales as n/n_t

A flat plate has always a worse efficiency than an airfoil

The Froude number is the ratio of aerodynamic to inertial forces