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  • 1
    Publication Date: 2011-08-23
    Description: The XV-15 Tilt-Rotor wing has six major aeroelastic modes that are close in frequency. To precisely excite individual modes during flight test, dual flaperon exciters with automatic frequency-sweep controls were installed. The resulting structural data were analyzed in the frequency domain (Fourier-transformed). Modal frequencies and damping were determined by performing curve fits to frequency-response magnitude and phase data. Results are given for the XV-15 with its original metal rotor blades. Frequency and damping values are also compared with new predictions by two different programs, CAMRAD and ASAP.
    Keywords: Aircraft Design, Testing and Performance
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  • 2
    Publication Date: 2011-08-19
    Description: The Rotor Systems Research Aircraft (RSRA) was flown in the airplane configuration. Eleven successful flights were made from May 8 to October 3, 1984. The takeoff and landing method was demonstrated and the resultant parameters were obtained. Control power data were obtained. In addition, main rotor hub drag, airplane configuration acoustics data, and aircraft stability data were obtained. Hub drag, acoustics, and stability will be separately reported in more detail. The tail rotor was installed for all tests.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
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  • 3
    Publication Date: 2011-08-19
    Description: The Rotor Systems Research Aircraft helicopter technology demonstration test bed incorporates an active isolator system which reduces the rotor vibrations that are transmitted to the airframe and allows the simultaneous measurement of all six forces and moments generated by the rotor. The first full system calibration was performed in 1983 to verify the system's static load measurement capabilities; the analysis of the data encompassed multiple linear regressions to determine calibration matrices for different data sets, and a hysteresis removal algorithm for the estimation of in-flight measurement errors. The results obtained indicate that the active isolator system meets most performance predictions.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
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  • 4
    Publication Date: 2011-08-19
    Description: The XV-15 tilt-rotor wing has six major aeroelastic modes that are close in frequency. To precisely excite individual modes during flight test, dual flaperon exciters with automatic frequency-sweep controls were installed. The resulting structural data were analyzed in the frequency domain (Fourier-transformed). Modal frequencies and damping were determined by performing curve fits to frequency-response magnitude and phase data. Results are given for the XV-15 with its original metal rotor blades. Frequency and damping values are also compared with predictions by two different programs, CAMRAD and ASAP.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Journal of Aircraft (ISSN 0021-8669); 26; 667-674
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  • 5
    Publication Date: 2011-08-19
    Description: The XV-15 Tilt-Rotor wing has six major aeroelastic modes that are close in frequency. To precisely excite individual modes during flight test, dual flaperon exciters with automatic frequency-sweep controls were installed. The resulting structural data were analyzed in the frequency domain (Fourier transformed) with cross spectral and transfer function methods. Modal frequencies and damping were determined by performing curve fits to transfer function magnitude and phase data and to cross spectral magnitude data. Results are given for the XV-15 with its original metal rotor blades. Frequency and damping values are also compared with earlier predictions.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Vertica (ISSN 0360-5450); 13; 1, 19; 51-62
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  • 6
    Publication Date: 2018-06-06
    Description: A CAMRAD II model of the V-22 Osprey tiltrotor was constructed for the purpose of analyzing the effects of blade design changes on whirl flutter. The model incorporated a dual load-path grip/yoke assembly, a swashplate coupled to the transmission case, and a drive train. A multiple-trailer free wake was used for loads calculations. The effects of rotor design changes on whirl-mode stability were calculated for swept blades and offset tip masses. A rotor with swept tips and inboard tuning masses was examined in detail to reveal the mechanisms by which these design changes affect stability and loads. Certain combinations of design features greatly increased whirl-mode stability, with (at worst) moderate increases to loads.
    Keywords: Aircraft Design, Testing and Performance
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  • 7
    Publication Date: 2019-06-28
    Description: The Rotor Systems Research Aircraft (RSRA) active-isolator system is designed to reduce rotor vibrations transmitted to the airframe and to simultaneously measure all six forces and moments generated by the rotor. These loads are measured by using a combination of load cells, strain gages, and hydropneumatic active isolators with built-in pressure gages. The first static calibration of the complete active-isolator rotor balance system was performed in l983 to verify its load-measurement capabilities. Analysis of the data included the use of multiple linear regressions to determine calibration matrices for different data sets and a hysteresis-removal algorithm to estimate in-flight measurement errors. Results showed that the active-isolator system can fulfill most performance predictions. The results also suggested several possible improvements to the system.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA-TM-88211 , A-86115 , NAS 1.15:88211
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  • 8
    Publication Date: 2019-06-28
    Description: The fixed-wing, airplane configuration flight-test results of the Rotor System Research Aircraft (RSRA), NASA 740, at Ames/Dryden Flight Research Center are documented. Fourteen taxi and flight tests were performed from December 1983 to October 1984. This was the first time the RSRA was flown with the main rotor removed; the tail rotor was installed. These tests confirmed that the RSRA is operable as a fixed-wing aircraft. Data were obtained for various takeoff and landing distances, control sensitivity, trim and dynamics stability characteristics, performance rotor-hub drag, and acoustics signature. Stability data were obtained with the rotor hub both installed and removed. The speed envelope was developed to 261 knots true airspeed (KTAS), 226 knots calibrated airspeed (KCAS) at 10,000 ft density altitude. The airplane was configured at 5 deg. wing incidence with 5 deg. wing flaps as a normal configuration. Level-flight data were acquired at 167 KCAS for wing incidence from 0 to 10 deg. Step inputs and doublet inputs of various magnitudes were utilized to acquire dynamic stability and control sensitivity data. Sine-wave inputs of constantly increasing frequency were used to generate parameter identification data. The maximum load factor attained was 2.34 g at 206 KCAS.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA-TM-86789 , A-85363 , NAS 1.15:86789
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  • 9
    Publication Date: 2019-06-28
    Description: The Rotor Systems Research Aircraft (RSRA) is a compound helicopter that was test flown as a fixed wing aircraft, with the main rotor blades removed and the rotor hub installed. An onboard rotor load measurement system measured the resulting rotor hub drag and lift. Measured hub drag and lift are plotted for comparison to that predicted by full scale and 1/6 scale model wind tunnel tests. The success of the demonstration gives confidence that planned improvements to the RSRA will allow high accuracy hub drag and lift measurements to be made in flight on a routine research basis.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA-TM-86764 , REPT-85288 , NAS 1.15:86764
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  • 10
    Publication Date: 2018-12-01
    Description: The Rotor Systems Research Aircraft (RSRA) is a compound helicopter that was test flown as a fixed-wing aircraft, with the main rotor blades removed and the rotor hub installed. An onboard rotor load-measurement system measured the resulting rotor hub drag and lift. Measured hub drag and lift are plotted for comparison to that predicted by full-scale and 1/6-scale model wind-tunnel tests. The success of the demonstration gives confidence that planned improvements to the RSRA will allow high-accuracy hub drag and lift measurements to be made in flight on a routine research basis.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
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