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Helicopter stability during aggressive maneuvers

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Date Issued:
2012
Summary:
The dissertation investigates helicopter trim and stability during level bank-angle and diving bank-angle turns. The level turn is moderate in that sufficient power is available to maintain level maneuver, and the diving turn is severe where the power deficit is overcome by the kinetic energy of descent. The investigation basically represents design conditions where the peak loading goes well beyond the steady thrust limit and the rotor experiences appreciable stall. The major objectives are: 1) to assess the sensitivity of the trim and stability predictions to the approximations in modeling stall, 2) to correlate the trim predictions with the UH-60A flight test data, and 3) to demonstrate the feasibility of routinely using the exact fast-Floquet periodic eigenvector method for mode identification in the stability analysis. The UH-60A modeling and analysis are performed using the comprehensive code RCAS (Army's Rotorcraft Comprehensive Analysis System). The trim and damping predictions are based on quasisteady stall, ONERA-Edlin vi (Equations Differentielles Lineaires) and Leishman-Beddoes dynamic stall models. From the correlation with the test data, the strengths and weaknesses of the trim predictions are presented.
Title: Helicopter stability during aggressive maneuvers.
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Name(s): Mohan, Ranjith.
College of Engineering and Computer Science
Department of Ocean and Mechanical Engineering
Type of Resource: text
Genre: Electronic Thesis Or Dissertation
Date Issued: 2012
Publisher: Florida Atlantic University
Physical Form: electronic
Extent: xxii, 157 p. : ill. (some col.)
Language(s): English
Summary: The dissertation investigates helicopter trim and stability during level bank-angle and diving bank-angle turns. The level turn is moderate in that sufficient power is available to maintain level maneuver, and the diving turn is severe where the power deficit is overcome by the kinetic energy of descent. The investigation basically represents design conditions where the peak loading goes well beyond the steady thrust limit and the rotor experiences appreciable stall. The major objectives are: 1) to assess the sensitivity of the trim and stability predictions to the approximations in modeling stall, 2) to correlate the trim predictions with the UH-60A flight test data, and 3) to demonstrate the feasibility of routinely using the exact fast-Floquet periodic eigenvector method for mode identification in the stability analysis. The UH-60A modeling and analysis are performed using the comprehensive code RCAS (Army's Rotorcraft Comprehensive Analysis System). The trim and damping predictions are based on quasisteady stall, ONERA-Edlin vi (Equations Differentielles Lineaires) and Leishman-Beddoes dynamic stall models. From the correlation with the test data, the strengths and weaknesses of the trim predictions are presented.
Identifier: 794979622 (oclc), 3342237 (digitool), FADT3342237 (IID), fau:3884 (fedora)
Note(s): by Ranjith Mohah.
Thesis (Ph.D.)--Florida Atlantic University, 2012.
Includes bibliography.
Electronic reproduction. Boca Raton, Fla., 2012. Mode of access: World Wide Web.
Subject(s): Helicopters -- Aerodynamics
Helicopters -- Control systems
Rotors (Helicopters) -- Aerodynamics
Stability of helicopters
Vibration (Aeronautics) -- Damping
Persistent Link to This Record: http://purl.flvc.org/FAU/3342237
Use and Reproduction: http://rightsstatements.org/vocab/InC/1.0/
Host Institution: FAU