Submission Details: Please submit your individual assignment in a PDF format via Blackboard
Please note the page limit is a maximum and not a requirement and please do use equations,figures, and diagrams where appropriate. All figures must be your own or referenced clearly.
You are free to write and draw by hand or complete your answers on a computer – just make sure that the final document is in a PDF format.
Part A – Axes, Balance and Stability
Figure Q1 shows the body axes of an aircraft and the earth axes that these can be referenced to.
1)Explain in your own words why we use the body axes and earth axes, what they are,and the relationship between them. 10 marks
2)Define the wind axes and explain how they are related to the motion of the aircraft in the presence of a steady wind. How might these appear within a flight dynamics model? 10 marks
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. 10 marks
4)Explain the link between Figure Q3 and 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. 15 marks
5)State what is meant by the manoeuvre margin and explain the difference between the manoeuvre point and the neutral point. 5 marks
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. 30 marks
7)What do we mean by the terms ‘trimming’ and ‘linearisation’ with regard to the rigid body equations of motion for an aircraft? 20 marks
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. 10 marks
9)Unfortunately, a PhD student has made a mistake when re-programming the autopilot. The inboard control surfaces on the wing have now been linked in as the ailerons and the outboard control surfaces as the flaps.On the assumption that each control surface is independently driven and zeroed correctly, use strip theory to derive an expression for the reduction in roll authority due to this error. Include any assumptions you make in the derivation and comment on the result. 20 marks
10)It turns out the PhD student has also failed to connect the left ruddervator control surface (See Figures Q9 and Q10) to the autopilot which means that only the right ruddervator is functional. Describe the effect this will have on the flight of the Albatross using diagrams and equations where appropriate. 10 marks
11)Identify the five sections in the flight where the aircraft is trimmed for a given speed.From this data identify the minimum sink rate for this configuration of the glider. Note this flight was with the 18 metre wingtip configuration and not the 20 metre as shown in Figure Q11. Identify any assumptions and difficulties that you have had in finding this value. 20 marks
12)Compare the value calculated in question 11 with the flight polar given in the DG1000S flight manual. In addition, what effect do the airbrakes have on the sink rate?How might these be used on the approach to landing? 10 marks
13)Please provide a short description of the five modes of motion that are found in the analysis of a conventional aircraft configuration. These must be in your own words,and please provide a sketch showing where you would expect to find them on the complex plane. 10 marks
14)From the glider flight data, you should be able to identify the phugoid mode. Provide any relevant parameters you can from the response given. 20 marks
Note: the flight simulators are available for your use in Queens Building. Please do feel free to use these to compare your results to the glider simulation.
Hints & Tips:
- Useful sources for this assignment include your Lecture Notes; online sources such as the ESDU data sheets; ‘Flight Dynamics Principles’ by M V Cook; ‘Aircraft Control &Simulation’ by Stevens & Lewis & other Flight Dynamics books. Whilst it is possible to complete this assignment using your notes alone, further reading will aid your understanding.
- Please do use other references as well where appropriate; make sure you cite them properly.
- The use of equations and figures is vital in order to allow you to fully explain the concepts within this assignment.
- Please note and explain any assumptions you have made in your answers.
- The eigenvalues of a matrix in Matlab can be found using ‘eig(matrix)’. The eigenvalues and eigenvectors of a matrix can be found using ‘[V,D] = eig(matrix)’. Damping ratios can be found using ‘damp(matrix)’.