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  • 1985-1989  (3)
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  • 1
    facet.materialart.
    Unknown
    Lateral noise attenuation of the advanced propeller of the propfan test assessment aircraft (1989)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Lateral noise attenuation characteristics of the advanced propeller are determined using the flight test results of the testbed aircraft, Propfan Test Assessment (PTA), with a single, large-scale propfan. The acoustic data were obtained with an array of ground-mounted microphones positioned at distances up to 2.47 km (8100 feet) to the side of the flight path. The aircraft was flown at a Mach number of 0.31 for a variety of operating conditions. The lateral noise attenuation in a frequency range containing the blade passage frequency of the propeller was found to have positive magnitudes on the propfan side and negative magnitudes on the opposite side. The measured attenuation exhibits a strong dependence upon the elevation angle. The results also display a clear dependence upon the angle at which the propeller and nacelle are mounted on the wing (inflow angle).
    Keywords: ACOUSTICS
    Type: AIAA PAPER 89-1057
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 2
    facet.materialart.
    Unknown
    Installed propfan (SR-7L) far-field noise characteristics (1989)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Far-field noise characteristics of the SR-7L single-rotor propfan were obtained from the Propfan Test Assessment (PTA) aircraft flight tests. The aircraft was flown at low altitudes (about 310m) above the ground at a constant speed of about 92 m/sec. The acoustic data were acquired with an array of ground-flush microphones positioned on both sides of the flight path. Propfan-generated noise levels were extracted from the total aircraft noise, and these data were then used to study the far-field noise characteristics. The directivities at the polar and azimuthal planes, and the variations of the blade-order tone levels with propfan power and blade tip Mach number were derived. The effect of inflow angle was studied by changing the nacelle tilt angle. The levels and the directivity were very sensitive to the nacelle tilt angle (i.e., inflow angle). The noise levels in the aft quadrant were found to be higher than in the forward quadrant. Also, the noise levels on the starboard side of the aircraft were found to be higher than on the port side. The noise levels increase with propfan power and rotational speed.
    Keywords: ACOUSTICS
    Type: AIAA PAPER 89-1056
    Format: text
    Location Call Number Expected Availability
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    NASA TECHNICAL REPORTS
  • 3
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    Unknown
    Propfan Test Assessment (PTA): Flight test report (1989)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The Propfan Test Assessment (PTA) aircraft was flown to obtain glade stress and noise data for a 2.74m (9 ft.) diameter single rotation propfan. Tests were performed at Mach numbers to 0.85 and altitudes to 12,192m (40,000 ft.). The propfan was well-behaved structurally over the entire flight envelope, demonstrating that the blade design technology was completely adequate. Noise data were characterized by strong signals at blade passage frequency and up to 10 harmonics. Cabin noise was not so high as to preclude attainment of comfortable levels with suitable wall treatment. Community noise was not excessive.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-182278 , NAS 1.26:182278 , LG89ER0026
    Format: application/pdf
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    NASA TECHNICAL REPORTS
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