Advanced Rotorcraft Brownout Aerodynamic Analysis and Flight Simulation

A critical operational problem for Army rotorcraft is "brownout" caused by excessive dust and debris kicked up by helicopter rotorwash during take-off and landing. This can eliminate visibility and severely damage engine parts and rotor blades. CDI recently completed a two-year effort for the U.S. Army developing a physics-based brownout module that plugs into flight simulations to identify, characterize and visualize brownout clouds for general aircraft, wind, and flight maneuvers. The brownout module provides a high level of physical fidelity in real-time by leveraging key technologies previously developed at CDI including:
  1. CDI's state-of-the-art, CHARM rotary-wing wake model and fast panel fuselage/ground surface model;
  2. CDI's MAST Multiple Aircraft Simulation Tool;
  3. CDI's LDTRAN particle entrainment and transport model;
  4. CDI's OpenSceneGraph multi-viewpoint graphics rendering technology.
The new brownout module was recently installed in 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 on Redstone Arsenal in Huntsville, AL.

Brownout Solution - EH-101 in Level Flight Near the Ground

Real-time BROWNOUT analysis cloud animation

Video from U.S. Army's BHIVE flight simulator
using CDI's Real-Time Brownout Module

  • Advanced, physics-based model of brownout
  • Supports both high resolution analysis and real time flight simulation
  • Fully-coupled rotor wake/fuselage solution
  • Stand alone analysis or module that couples into flight simulations


The BROWNOUT analysis tool will provide a better understanding of how aircraft configuration, weight, flight speed and trajectory combine with environmental condition (e.g. wind speed and direction) to affect visibility and foreign object damage in sand/dust/snow laden environments. The greatest benefit of this tool will be to reduce the extreme danger of sudden zero-visibility operation of military and search and rescue (SAR) rotorcraft in the field. Other applications include:
  • Improved flight simulator modeling and training in brownout conditions
  • Improved mission planning accounting for brownout/whiteout conditions for single and multiple aircraft operations - (e.g. SAR missions in ice and snow as well as military operations)
  • Improved aircraft configuration design through evaluation of brownout and rotorwash impact, (e.g. evaluation of future Heavy Lift Rotorcraft concepts)
  • Improved information on dust cloud characteristics to support the development of onboard sensing devices to assist pilot situational awareness during brownout
  • Improved analysis of debris ingestion into engine parts, debris impact damage to rotor blades, and flight through clouds of chemical/biological agents.

For more information, contact Dan Wachspress at (609)-538-0444 x114

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