  A comprehensive helicopter flight dynamics code is developed based on the
UH-60 helicopter and named Texas A\&M University Rotorcraft Analysis Code
(TRAC). This is a complete software package, which could perform trim analysis
to autonomous flight simulation and the capability to model any helicopter
configuration. Different components of the helicopter such as the main rotor,
tail rotor, fuselage, vertical tail, and horizontal tail are modeled
individually as different modules in the code and integrated to develop a
complete UH-60 model. Since the code is developed on a module basis, it can be
easily modified to adopt another component or configure a different helicopter.
TRAC can predict the dynamic responses of both the articulated rotor blades and
the helicopter fuselage and yields the required pilot control inputs to achieve
trim condition for different flight regimes such as hover, forward flight,
coordinated turn, climb/descent, etc. These trim results are validated with the
test data obtained from the UH-60 flight tests conducted by the US Army. Beyond
trim analysis, TRAC can also generate linearized models at various flight
conditions based on a first-order Taylor series expansion. The extracted linear
models show realistic helicopter dynamic behavior and were used to simulate a
fully autonomous flight that involves a UH-60 helicopter approaching a ship and
landing on the deck by implementing a Linear Quadratic Regulator (LQR) optimal
controller.
