| When wind flows around a large structure such as an airplane hangar (depicted above), it is broken into eddies, or turbulent airflow. Data collected at the San Francisco Coast Guard hangar was used to create the turbulence model for this simulation.
OBJECTIVES
1. Implement and evaluate a new rotorcraft turbulence model. Compare to preexisting models and flight test data.
2. Implement new ("modern") control laws developed by Sikorsky for the UH-60A to improve handling qualities under conditions of poor visibility.
HISTORY
The UH-60 debuted in 1974. Developed by Sikorsky, the Black Hawk was designed to replace the Army's UH-1 Series "Huey" helicopter. The Black Hawk is a versatile craft, capable of numerous operations, including troop transport, medical evacuations, and reconnaissance.
The Vertical Motion Simulator's (VMS) rotorcraft model (Gen Hel) was created by Sikorsky and was first implemented at NASA Ames in 1981. It's a general helicopter model that can be customized for individual rotorcraft simulations. The VMS has been the site of many UH-60 simulations, including ANOE IV in 1996, Partial Authority in 1998, AutoCue in 2000, and most recently, JSHIP in 2001.
TALK TO ME ABOUT "MODERN TURB"
"Modern Turb" takes its name from two aspects of the simulation. "Modern" refers to modern control laws. When a pilot "steers" a high-performance aircraft, there isn't always a direct mechanical linkage between the control stick in the cockpit and the actuators that move the flight control surfaces. Instead, the pilot's actions are filtered through a set of algorithms called flight control laws. These laws interpret the pilot's inputs and determine how the aircraft responds to the pilot.
"Turb" is short for "turbulence." Turbulence in this instance refers to unseen air movement, such as that generated by thunderstorms or large obstructions. Rotorcraft turbulence models are usually based upon those for fixed-wing craft. However, these models do not work when the rotorcraft hovers; thus, the effects of turbulence are usually excluded from handling qualities research. Recently, though, researchers have developed turbulence models specific to rotorcraft.
CURRENT SIMULATION
The current simulation marks the inaugural test of a new rotorcraft turbulence model in a piloted simulation. Data gathered during the simulation will be compared to actual flight data for evaluation of the turbulence model's validity. Additionally, Sikorsky has developed new control laws for the Black Hawk that aid the pilot in controlling and stabilizing the craft under poor visual conditions. These control laws will be tested in conjunction with the turbulence model under different wind and visual conditions, and pilots will be asked to perform several flight maneuvers, including hover, pirouette, and slalom. Data gathered during this simulation will reduce risk to both pilot and aircraft in a subsequent flight test evaluation on an EH-60L helicopter planned for later this year.
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