Executive Summary
This project is a continuation of the 2004 University of Adelaide Mechanical Engineering
final year VTOL project, which aimed to develop a controlled and stable VTOL model
aircraft based on the F-35 Joint Strike Fighter. Last year’s project group was unable to
complete the project for several reasons, primarily because of the poor performance of the
internal combustion engines. Due to advances in electric motor and battery technology,
the use of electric motors in now a feasible option and has been chosen for this year’s
project. An investigation was performed to re-evaluate the most suitable aircraft upon
which to base this year’s design. This research identified that the V-22 Osprey was the
most suitable platform. The primary advantage in using the V-22 Osprey as opposed to
the F- 35 was the higher thrust to weight ratio achievable using propellers.
Several designs were considered during the concept evolution, with each concept compared
with the design requirements. The final concept which met all requirements was then
modelled in SolidEdge where further details were considered. The design consists of an
Aluminium chassis with rotating wing arms controlled by servo motors allowing for tilt-
rotor operation. Control simplifications use this wing arm rotation along with a rear
tail-fan to directly control all three rotational degrees of freedom.
Thrust providing components were selected to best satisfy the constraints of cost, weight
and power. Ultimately two-blade fixed-pitch propellers were chosen to be mounted radially
to brushless motors via a planetary gearbox. These motors are controlled using an
electronic speed controller and powered by on-board Lithium Polymer batteries. Using
software based propeller theory these components were shown to produce adequate thrust.
To facilitate the creation of an appropriate control system using the physical
characteristics of the model aircraft, a mathematical representation of the system
was obtained by following several closely related examples. Using this mathematical
representation a state space controller was developed using a Reduced-Order Observer
and tuned using LQR Optimal Control. Another control technique, Proportional Integral
Derivative (PID) control, was also used as a controller for the aircraft. While the PID
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