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ENGINEERING TRIPOS PART IIB – 2012/2013

Module 4A4 - Aircraft Stability and Control

Leader:	Dr W.R. Graham(wrg@eng)
Timing:	Michaelmas and Lent Terms
Prerequisites:	A working knowledge of Part IA and IB fluid mechanics and control theory will be assumed.
Structure:	14 lectures + 2 examples classes + coursework
Capacity:	The flight test part of this module has a number limit of 30. If it is oversubscribed, selection will be made on a competitive basis, subject to priority being given to students in Engineering Areas 3 (Aerospace and Aerothermal Engineering) and 8 (Instrumentation and Control). The module can also be taken without participating in the flight tests.
Assessment:	*Material / Format / Timing / Marks* Coursework / Report / week 9 Lent Term / 100 %

AIMS

This module aims to develop an understanding of the dynamics of an aircraft in flight, and an appreciation of how their characteristics may be improved using automatic control systems.

LECTURE SYLLABUS

Aircraft Stability (8L, Michaelmas term, Dr W.R. Graham)

Aircraft equations of motion, small disturbance form, stability derivatives.
Longitudinal motion: phugoid mode, short period oscillation and approximate forms.
Lateral motion: roll subsidence, dutch roll, spiral mode and approximate forms.
Static stability of aircraft: longitudinal stability, directional stability, lateral stability.

Automatic Control Systems (6L, Lent term, Dr W.R. Graham)

Root locus plots and their use in designing feedback control systems.
Response to control inputs.
Autopilots: pitch and roll angle control, effect on aircraft dynamic response and stability.
Stability augmentation systems: pitch rate SAS & yaw damper as means of improving dynamic stability characteristics, relaxed static stability.
Command augmentation systems: C-star criterion as basis for longitudinal CAS in fly-by-wire aircraft.

COURSEWORK

Flight tests on Cranfield Jetstream 31 flying laboratory. Assessment of static and dynamic stability based on flight test data. Design study for an automatic control system for the aircraft. A report on the stability assessment and design study forms the basis for module assessment. The flight tests will take place at the end of the Michaelmas term.

OBJECTIVES

On completion of the module students should:

Appreciate how the equations of motion for an aircraft follow from Newton's second law, and how they may be simplified to the small-disturbance form;
Understand how the free modes of motion follow from the equations of motion, and be aware of the approximate derivations of the modes;
Know the factors determining the static stability of an aircraft, and understand the significance of the position of the centre of gravity;
Have a knowledge of basic control strategies for autopilots, and their effects on aircraft stability;
Appreciate that the dynamic characteristics of the aircraft may be improved by feedback control, and understand how this concept applies to stability augmentation systems, and command augmentation systems.

REFERENCES

Please see the Booklist for Group A Courses for references for this module.

Last updated: June 2012
teaching-office@eng.cam.ac.uk