The image below shows the free body diagram of an aircraft, including the angles between the different reference frames.

Question

Which of the following statements is true?

Angle a is the flight path angle, angle c is an angle of attack, angle d is the pitch attitude.

Angle b is an angle of attack, angle d is the pitch attitude, angle c is the flight path angle.

Angle b is the angle of attack, angle c is the pitch attitude, angle d is the flight path angle

Angle a is the angle of attack, angle b is the pitch attitude, angle d is the flight path angle

Angle d is a pitch attitude, angle c is an angle of attack and angle b is the flight path angle.

Answer 1

To determine which statement about the angles in the free body diagram of an aircraft is true, we need to define the terms related to aircraft orientation and flight.

1. Flight Path Angle (γ) - This is the angle between the horizontal plane and the flight path of the aircraft. It indicates the direction of movement through the air.

2. Angle of Attack (α) - This is the angle between the chord line of the wing and the relative wind (the direction of the airflow). It is crucial for understanding lift generation.

3. Pitch Attitude (θ) - This refers to the angle between the aircraft's nose and the horizontal plane (the horizon). It describes how "nose-up" or "nose-down" the aircraft is relative to the ground.

Now, we will break down the provided options based on these definitions:

1. Option 1: Angle a is the flight path angle, angle c is an angle of attack, angle d is the pitch attitude.
2. Option 2: Angle b is an angle of attack, angle d is the pitch attitude, angle c is the flight path angle.
3. Option 3: Angle b is the angle of attack, angle c is the pitch attitude, angle d is the flight path angle.
4. Option 4: Angle a is the angle of attack, angle b is the pitch attitude, angle d is the flight path angle.
5. Option 5: Angle d is a pitch attitude, angle c is an angle of attack, and angle b is the flight path angle.

To identify the correct answer, we would need to visualize the diagram, but generally, the correct matching of the definitions with angles in a typical free body diagram setup could be as follows:

• Angle a often represents the flight path angle (γ).
• Angle b typically represents the angle of attack (α).
• Angle d could denote the pitch attitude (θ).
• Angle c tends to represent the relationship between other angles but would likely not fit the definitions of α, γ, or θ in the standard context.

Given this reasoning, the most plausible answer might be:

Angle a is the flight path angle, angle b is an angle of attack, angle d is the pitch attitude.

Since none of the proposed options match this directly, it would be best to review the diagram to confirm which option closely aligns with the established definitions of the angles. If you refer to the visual reference again, it should help finalize which answer is indeed accurate.