Author: Reginald C. Murrell
Publisher:
ISBN:
Category :
Languages : en
Pages : 279
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Testing was conducted to evaluate handling qualities of the UH-60A helicopter with the pitch bias actuator (PBA) centered and electrically disconnected and with various modes of automatic flight control system (AFCS) degradation. A total of 46.4 productive flight hours were flown between 4 April 1985 and 2 July 1986. Two shortcomings and two Prime Item Development Specification noncompliances were identified. The handling qualities of the UH-60A helicopter with the PBA centered and electrically disconnected are essentially unchanged from those with the PBA operational, except for; (1) slightly degraded static longitudinal stability, (2) slightly degraded dynamic stability, and (3) a shortcoming, the poor maneuvering stability characteristics. One additional shortcoming is the strong pitch-due-to-sideslip coulping, which is unrelated PBA centered and electrically disconnected are satisfactory to continue flight under both visual and instrument meteorological conditions with any degradation of the AFCS.
Author:
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ISBN:
Category : Aeronautics
Languages : en
Pages : 964
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Author:
Publisher:
ISBN:
Category : Government reports announcements & index
Languages : en
Pages : 1026
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Author:
Publisher:
ISBN:
Category : Government reports announcements & index
Languages : en
Pages : 1028
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Author:
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 328
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Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 520
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Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 518
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Book Description
A selection of annotated references to unclassified reports and journal articles that were introduced into the NASA scientific and technical information system and announced in Scientific and technical aerospace reports (STAR) and International aerospace abstracts (IAA).
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 516
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Author:
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ISBN:
Category : Government publications
Languages : en
Pages : 1258
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 98
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Book Description
Helicopter slung-load operations are common in both military and civil contexts. Helicopters and loads are often qualified for these operations by means of flight tests, which can be expensive and time consuming. There is significant potential to reduce such costs both through revisions in flight-test methods and by using validated simulation models. To these ends, flight tests were conducted at Moffett Field to demonstrate the identification of key dynamic parameters during flight tests (aircraft stability margins and handling-qualities parameters, and load pendulum stability), and to accumulate a data base for simulation development and validation. The test aircraft was a UH-60A Black Hawk, and the primary test load was an instrumented 8- by 6- by 6-ft cargo container. Tests were focused on the lateral and longitudinal axes, which are the axes most affected by the load pendulum modes in the frequency range of interest for handling qualities; tests were conducted at airspeeds from hover to 80 knots. Using telemetered data, the dynamic parameters were evaluated in near real time after each test airspeed and before clearing the aircraft to the next test point. These computations were completed in under 1 min. A simulation model was implemented by integrating an advanced model of the UH-60A aerodynamics, dynamic equations for the two-body slung-load system, and load static aerodynamics obtained from wind-tunnel measurements. Comparisons with flight data for the helicopter alone and with a slung load showed good overall agreement for all parameters and test points; however, unmodeled secondary dynamic losses around 2 Hz were found in the helicopter model and they resulted in conservative stability margin estimates.
