Interservice/Industry Training, Simulation, and Education Conference (I/ITSEC) 2008
2008 Paper No. 8177 Page 1 of 12
Physics Based Modeling of Helicopter Brownout for Piloted Simulation
Applications
Daniel A. Wachspress, Glen R. Whitehouse,
Jeffrey D. Keller
Kevin McClure, Phillip Gilmore, Michael
Dorsett
Continuum D
namics
Inc. SAIC
Redstone Arsenal
Ewin
NJ Huntsville
AL
dan@continuum-dynamics.com,
glen@continuum-dynamics.com,
jeff@continuum-dynamics.com
kevin.r.mcclure@gmail.com,
phillip.d.gilmore@us.army.mil,
michael.f.dorsett@us.army.mil
ABSTRACT
The entrainment and circulation of ground debris by rotorcraft downwash over unprepared fields, often referred to
as “brownout”, represents a critical safety issue for rotary-wing aviation today. Helicopter pilots often first
experience brownout in actual flight conditions, and it is desirable to advance the state of training simulations by
providing high fidelity modeling of brownout conditions during landing and take-off. While semi-empirical
brownout visual models are available in training simulators, these models lack the level of fidelity required to
capture the complex interaction of rotor downwash, ambient winds, and the effect of vehicle maneuvering, in
combination with debris transport and visual obscuration effects due to the wide range of possible surface cover
materials and ground topology. This paper describes the development and integration of an advanced, physics-
based model of rotorcraft brownout for piloted simulation. A central element to the model is an advanced rotorwash
model based on real-time, free vortex wake methods to represent the complex flow field of maneuvering rotorcraft
in the proximity of the ground. This rotorwash model is combined with debris entrainment and transport models to
determine the visible obscuration effects of brownout based on physical principles. The models are incorporated
into a real-time module that has been integrated into the U.S. Army Advanced Prototyping Engineering and
Experimentation (APEX) laboratory rotorcraft flight simulation for the UH-60M, CH-47F and ARH aircraft and
image generator system at the System Simulation and Development Directorate at Redstone Arsenal in Huntsville,
AL. This paper provides an overview of the brownout model and validation, and describes the software
architecture, integration approach, and results from this successful integration.
ABOUT THE AUTHORS
Daniel A. Wachspress is a Senior Associate with Continuum Dynamics, Inc. in Ewing, New Jersey, where he has
been directly involved in the research, development and implementation of rotorcraft computer models for over
twenty years. He is the chief architect for numerous analysis and simulation tools for rotorcraft and has led the
development of real-time rotor wake and brownout models for real-time simulation applications. He earned B.S.E.
and M.S.E. degrees in Mechanical and Aerospace Engineering from Princeton University in 1980 and 1982.
Glen R. Whitehouse is an Associate with Continuum Dynamics, Inc., where he specializes in rotorcraft
aeromechanics and CFD for flight mechanics applications. At CDI he has led the development of novel Eulerian
wake modeling tools for accurately simulating vortical flows and is the principal investigator of an ongoing effort to
develop both bio-kinetic/bio-mimetic aeromechanical modeling tools and a prototype unconventional flapping wing
MAV for the U.S. Air Force. He received a Ph.D. and D.I.C. from the Department of Aeronautics at Imperial
College, London in 2004 and his B.S. in Aeronautical Engineering and Mathematics from Clarkson University in
2000.
Jeffrey D. Keller is an Associate with Continuum Dynamics, Inc., where he has been since 1997. His professional
interests include air vehicle aerodynamics and flight dynamics modeling and aircraft flight controls development,
