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  • 11
    Publikationsdatum: 2019-07-13
    Beschreibung: Work is currently underway at the NASA Lewis Research Center to develop an analytical method for predicting the performance degradation of a helicopter operating in icing conditions. A brief survey is performed of possibilities available to perform such a calculation along with the reasons for choosing the present approach. A complete description of the proposed jobstream is given as well as a discussion of the present state of the development.
    Schlagwort(e): AERODYNAMICS
    Materialart: AHS Annual Forum; May 06, 1991 - May 08, 1991; Phoenix, AZ; United States
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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  • 12
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    In:  Other Sources
    Publikationsdatum: 2019-07-13
    Beschreibung: A NASA-sponsored consortium conducted an experimental program to investigate the characteristics of a model rotor under icing conditions. This project resulted in the first U.S. test of a heavily instrumented model rotor conducted in the controlled environment of a refrigerated wind tunnel, the NASA Lewis Icing Research Tunnel. The tunnel entry used a powered force model with a 1.83-m-diameter main rotor, with 0.124-m-chord main rotor blades fabricated specially for this experiment. Test conditions included a range of liquid water content and median volume droplet diameters that fell within the FAA and DOD icing envelopes. The test data show the effects of icing on rotor lift, rotor torque, blade loads, and vibration. Ice shapes and ice dimensions were taken, and molds were made of three ice shapes. High-speed movies were taken to document ice shedding. The results have been compared with analytical accretion predictions.
    Schlagwort(e): AIR TRANSPORTATION AND SAFETY
    Materialart: AHS, Annual Forum; May 21, 1990 - May 23, 1990; Washington, DC; United States
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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  • 13
    Publikationsdatum: 2019-07-13
    Beschreibung: Work is currently underway at the NASA Lewis Research Center to develop an analytical method for predicting the performance degradation of a helicopter operating in icing conditions. A brief survey is performed of possibilities available to perform such a calculation along with the reasons for choosing the present approach. A complete description of the proposed jobstream is given as well as a discussion of the present state of the development.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-CR-187076 , E-6026 , NAS 1.26:187076 , Annual Forum and Technology Display; May 06, 1991 - May 08, 1991; Phoenix, AZ; United States
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 14
    Publikationsdatum: 2019-07-13
    Beschreibung: A heavily instrumented sub-scale model of a helicopter main rotor was tested in the NASA Lewis Research Center Icing Research Tunnel (IRT) in September and November 1989. The four-bladed main rotor had a diameter of 1.83 m (6.00 ft) and the 0.124 m (4.9 in) chord rotor blades were specially fabricated for this experiment. The instrumented rotor was mounted on a Sikorsky Aircraft Powered Force Model, which enclosed a rotor balance and other measurement systems. The model rotor was exposed to a range of icing conditions that included variations in temperature, liquid water content, and median droplet diameter, and was operated over ranges of advance ratio, shaft angle, tip Mach number (rotor speed) and weight coefficient to determine the effect of these parameters on ice accretion. In addition to strain gage and balance data, the test was documented with still, video, and high speed photography, ice profile tracings, and ice molds. The sensitivity of the model rotor to the test parameters, is given, and the result to theoretical predictions are compared. Test data quality was excellent, and ice accretion prediction methods and rotor performance prediction methods (using published icing lift and drag relationships) reproduced the performance trends observed in the test. Adjustments to the correlation coefficients to improve the level of correlation are suggested.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-TM-103709 , E-5935 , NAS 1.15:103709 , AIAA PAPER 91-0660 , Aerospace Sciences Meeting; Jan 07, 1991 - Jan 10, 1991; Reno, NV; United States
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 15
    Publikationsdatum: 2019-08-16
    Beschreibung: The cost and time to certify or qualify a rotorcraft for flight in forecast icing has been a major impediment to the development of ice protection systems for helicopter rotors. Development and flight test programs for those aircraft that have achieved certification or qualification for flight in icing conditions have taken many years, and the costs have been very high. NASA, Sikorsky, and others have been conducting research into alternative means for providing information for the development of ice protection systems, and subsequent flight testing to substantiate the air-worthiness of a rotor ice protection system. Model rotor icing tests conducted in 1989 and 1993 have provided a data base for correlation of codes, and for the validation of wind tunnel icing test techniques. This paper summarizes this research, showing test and correlation trends as functions of cloud liquid water content, rotor lift, flight speed, and ambient temperature. Molds were made of several of the ice formations on the rotor blades. These molds were used to form simulated ice on the rotor blades, and the blades were then tested in a wind tunnel to determine flight performance characteristics. These simulated-ice rotor performance tests are discussed in the paper. The levels of correlation achieved and the role of these tools (codes and wind tunnel tests) in flight test planning, testing, and extension of flight data to the limits of the icing envelope are discussed. The potential application of simulated ice, the NASA LEWICE computer, the Sikorsky Generalized Rotor Performance aerodynamic computer code, and NASA Icing Research Tunnel rotor tests in a rotorcraft certification or qualification program are also discussed. The correlation of these computer codes with tunnel test data is presented, and a procedure or process to use these methods as part of a certification or qualification program is introduced.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-TM-106747 , E-9159 , NAS 1.15:106747 , European Rotorcraft Forum; Oct 04, 1994 - Oct 07, 1994; Amsterdam; Netherlands
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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