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Flight Dynamics > Test 1 Review > Flashcards

Test 1 Review Flashcards

1
Q

The equations of motion for an aircraft in flight are found by applying ______.

A

Newton’s second law of motion.

Yechout: Pg 163

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2
Q

What does the right-hand side of the EOM provide?

A

Applied forces and moments.

Yechout: Pg 163

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3
Q

What does the left-hand side of the EOM provide?

A

The aircraft response (the accelerations multiplied by the mass).

Yechout: Pg 163

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4
Q

For the body axis system, where is the origin (usually) placed?

A

The aircraft’s CG

Yechout: Pg 164

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5
Q

Describe the axis orientation of the body system with respect to the aircraft geometry.

A

The x-axis points from the CG out the nose of the aircraft. The z-axis lies in the longitudinal plane of symmetry and points down away from the belly. The y- axis points outward from the right wing completing the right-hand triad.

Yechout: Pg 164

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6
Q

Describe the orientation of the Earth-axis system.

A

The axis is fixed to the earth’s surface with the z-axis pointing toward the Earth’s core, the x-axis points north and the y-axis is east.

Yechout: Pg 164

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7
Q

The stability axis system is rotated relative to the body axis system through the __________.

A

Angle of attack.

Yechout: Pg 164

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8
Q

Newton’s second law is only valid in an _____.

A

Intertial reference frame.

Yechout: Pg 164

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9
Q

For the stability axis system, describe the orientation of the x-axis.

A

The x-axis points in the direction of the projection of the relative wind onto the xz plane of the aircraft.

Yechout: Pg 164-165

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10
Q

True or False

In the stability axis system, the y-axis is coincident with the y-axis in the body system.

A

True

Yechout: Pg 165

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11
Q

In the stability axis system, the z-axis is tiled toward the tail through _______.

A

The angle of attack.

Yechout: Pg 165

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12
Q

The gravitational force on the aircraft is usually expressed in what coordinate system?

A

Earth Axis System

Yechout: Pg 165

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13
Q

The aerodynamic forces on the aircraft are usually expressed in what coordinate system?

A

Stability axis system

Yechout: Pg 165

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14
Q

The thrust forces on the aircraft are usually expressed in what coordinate system?

A

Body axis system

Yechout: Pg 166

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15
Q

The azimuth angle is given by the Greek letter ____. This angle describes a rotation about the _____ axis.

A

Psi
Inertial z-axis

Yechout: Pg 166

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16
Q

The elevation angle is given by the Greek letter _____. The elevation angle is a rotation of the aircraft about the _____ axis.

A

Theta
Body attached y-axis

Yechout: Pg 166

17
Q

The roll angle is given by the Greek letter _____.

A

Phi

Yechout: Pg 166

18
Q

True or False

Euler angles must be orthogonal.

A

False

Phillips Pg 736

19
Q

What are the standard ranges of the Euler angles?

A

-180 < Phi < 180
-90 < Theta <90
0<= Psi <=360

Phillips Pg 739

20
Q

True or False

The inverse of the transformation matrix is its transpose.

A

True

Phillips Pg 741

21
Q

True or False
With respect to the aircraft kinematic equations; the inverse of the matrix relating the roll rates to the time derivatives of the Euler angles will equal its transpose.

A

False

Phillips Pg 742

22
Q

With respect to the Euler angles, is there a mathematical singularity, and if so, describe it.

A

Yes.
At Theta = 90 degrees.

Phillips Pg 742

23
Q

The singularity present in the integration of the Euler angles is commonly called ____.

A

Gimbal Lock

Phillips Pg 743

24
Q

True or False

The weight force expressed in the body axis system is independent of the aircraft’s heading.

A

True

25
Q

True or False
For a direction cosine matrix, if a column is given by x1 x2, and x3, the following equation holds for any column.
x1^2 + x2^2 + x3^2 = 1

A

True

W.Durham, Pg 20

26
Q

True or False

The inverse of a direction cosine is equal to its transpose.

A

True

W.Durham, Pg 20

27
Q

True or False
For direction cosine matrix T_12
T_12 * T_12 ^T == T_12

A

False
T_12 * T_12^T == I_3

W.Durham, Pg 21

28
Q

True or False

For a given direction cosine matrix, the squares of the row elements sum to unity.

A

True

W.Durham, Pg 21

29
Q

True or False

For a given direction cosine matrix, the products of offset row entries sum to 1.

A

False. They sum to zero.

t11t31 + t12t32 + t13*t33 ==0

W.Durham, Pg 21

30
Q

What numbers correspond to Euler rotations about a particular axis?

A 
1 = x rotation
2 = y rotation
3 = z rotation

W.Durham, Pg 21

31
Q

What Euler sequence is commonly used in flight dynamics?

A

321

W.Durham, Pg 22

32
Q

Give the common Euler angles associated with the body to the horizontal frame.

A

x y z
phi theta psi

W.Durham, Pg 27

33
Q

Give the common Euler angles associated with the body to wind frame.

A

x y z
0 alpha -betta

Note the negative on the sideslip angle beta.

W.Durham, Pg 27

34
Q

What is the equation for the state transition matrix?

A

[sI - A]^-1

W.Durham, Pg 114

35
Q

How do you find the characteristic equation for a state-space representation?

A

Take the determinant of the state transition matrix [sI - A]^-1 and set it equal to zero.

W.Durham, Pg 114

36
Q

What is the modal matrix?

A

A matrix whose columns are the system eigenvectors.

W.Durham, Pg 116

37
Q

True or False
With respect to Euler angles, the order of selection of axes in the rotation is arbitrary, but the same axis may not be used twice in succession.

A

True

W. Durham Pg. 21

38
Q

Which of the following Euler rotation is invalid?

a) 121
b) 313
c) 112

A

c). You cannot use a rotation twice in succession.

W.Durham Pg. 21

Flight Dynamics (7 decks)

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