Aircraft Longitudinal Static Stability

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What is the primary advantage of dividing stability and control analysis into longitudinal and lateral-directional analysis?

It simplifies the analysis by eliminating the need to consider moderate changes in angle of attack. (correct)

It enables the analysis to focus on the pitching moment about the center of gravity.

It reduces the importance of considering the wing's aerodynamic center.

It allows for a more detailed analysis of the aircraft's yaw and roll.

What is the definition of the aerodynamic center of the wing?

The point where the wing's drag is minimum.

The point about which the wing's pitching moment is constant with respect to angle of attack. (correct)

The point where the wing's pitching moment is zero.

The point where the wing's lift is maximum.

Where is the aerodynamic center of the wing typically located in subsonic flight?

At 25% of the MAC (correct)

At 50% of the MAC

At the trailing edge of the wing

At the leading edge of the wing

What is the effect of flap deflection on the wing's pitching moment?

It increases the pitching moment. (A) Signup and view all the answers

What can be ignored in the pitching moment equation due to its small value?

The pitching moment of the tail about its aerodynamic center (B) Signup and view all the answers

What is the significance of the wing being uncambered and untwisted?

The pitching moment about the aerodynamic center is zero. (D) Signup and view all the answers

What influences the pitching moments produced by the fuselage and nacelles?

Upwash and downwash produced by the wing (A) Signup and view all the answers

What is the purpose of the wing flap in a tailless aircraft?

To trim and control the aircraft (C) Signup and view all the answers

What is the effect of the propwash jet induced flowfield on the aircraft?

It influences the effective angle of attack of the tail and possibly the wing (C) Signup and view all the answers

What is the equation used to express the sum of moments about the cg?

Working equations (D) Signup and view all the answers

What is the term used to describe the vertical force produced at the propeller disk?

Fp (A) Signup and view all the answers

What is the purpose of dividing all terms by (qSwc) in the pitching moment equation?

To express the moments in coefficient form (D) Signup and view all the answers

What is the result of increasing the tail force to counteract a change in the trim condition?

Upward deflection of the elevators (D) Signup and view all the answers

What is the effect of a positive Cl change on the trim tab?

Requires a positive trim tab angular deflection (A) Signup and view all the answers

What is the purpose of deflecting the elevator downward to trim for a speed increase?

To decrease the angle of attack and lower the nose of the aeroplane (D) Signup and view all the answers

How does the position of the CG affect the pitch handling characteristics?

It affects the positive longitudinal static stability and pitch handling characteristics (C) Signup and view all the answers

What happens to the elevator deflection required to counter a forward CG movement during a manoeuvre with a load factor greater than one?

It is increased (D) Signup and view all the answers

What is the effect of an aft CG position on the response to elevator deflection?

A large response for the same angle of deflection (A) Signup and view all the answers

What type of stability is focused on the angle-of-attack stability derivatives?

Velocity stability (A) Signup and view all the answers

What happens to the thrust of a propeller when the aircraft velocity increases?

It decreases (D) Signup and view all the answers

What is the effect of a high-mounted propeller on an aircraft's velocity stability?

It is stabilizing (C) Signup and view all the answers

What is the approximate increase in static margin for every 1% MAC that the thrust axis is above the c.g.?

One-quarter of a percent (D) Signup and view all the answers

Why is a high-mounted propeller usually used only in seaplanes?

To provide water clearance (B) Signup and view all the answers

What is the effect of engine vertical position on velocity stability in jet aircraft?

It has little to no effect (C) Signup and view all the answers

What is the orientation of the X-axis in the Stability Axis System?

Aligned at the aircraft's angle of attack (C) Signup and view all the answers

Why is the Stability Axis System used in aerodynamics?

Because lift and drag are conveniently aligned with the axes (B) Signup and view all the answers

What is included in the calculation of nondimensional coefficients for moments?

The moment arm, dynamic pressure, and wing area (A) Signup and view all the answers

What is the positive direction of a moment in stability analysis?

Nose up or to the right (C) Signup and view all the answers

What is the significance of the yawing moment derivative with respect to sideslip?

It is a critical parameter in lateral stability (B) Signup and view all the answers

What does $N_v$ represent in stability analysis?

The pitching moment response to an elevator deflection (D) Signup and view all the answers