The goal of vertical takeoff and landing (VTOL) aircraft is to achieve operation from
relatively small airports and yet operate as a normal aircraft in level flight. An aircraft
taking off in a form similar to a rocket is inherently unstable. A control system using
adjustable jets can control the vehicle, as shown in the figure below.
R(s)
Σ
K
$\frac{1}{s^2 - 1(s + 4)}$
Y(s)
$\frac{s + 2}{s + 6}$
1. Determine the open-, closed-loop, and loop gain transfer functions. Determine if
the system is stable without the proportional gain controller. Plot the location of
poles and zeros for the open- and closed-loop transfer functions.
2. Using Routh's stability criterion, determine the range of the proportional control
gain K for which the closed-loop system is stable.
