AENG20001: Explain in your own words why we use the body axes and earth axes, what they are, and the relationship between them: Flight Dynamics and Control Assignment, UOB, UK

Part A – Axes, Balance and Stability

Figure Q1 shows the body axes of an aircraft and the earth axes that can be referenced.

1) Explain in your own words why we use the body axes and earth axes, what they are, and the relationship between them.

2) Define the wind axes and explain how they are related to the motion of the aircraft in the presence of steady wind. How might these appear within a flight dynamics model?

Figure Q3 below shows the CG limits for a commercial aircraft.

3) Explain the source of the different limits, the reason for the loops in the centre of the diagram and the terms MZFW, MLW and MTOW.

4) Explain the link between Figure Q3 and the longitudinal stability of the aircraft. How is this linked to the equation for elevator angle to trim? Use the terms static margin and neutral point within your answer.

5) State what is meant by the manoeuvre margin and explain the difference between the manoeuvre point and the neutral point.

Part B – Equations of Motion

6) Provide the key steps involved in the derivation of the equations of motion for a rigid body aircraft in your own words. Explain any underlying assumptions in your answer and discuss the role that the inertial terms play in the equations. You may choose to include part or all of the equations in your description if you wish.

7) What do we mean by the terms ‘trimming’ and ‘linearisation’ with regard to the rigid body equations of motion for an aircraft?

Part C – Strip Theory

8) In your own words explain the term ‘strip theory’ and how we have applied it in our course. Include in your answer a description of the associated limitations and assumptions.