Browsing by Author "Hyde, D."
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Item Open Access A measurement of the radiated noise on a subsonic jet aircraft in gliding flight(College of Aeronautics, 1963-06) Hyde, D.The noise radiated from a gliding subsonic jet aircraft was measured in flight by a probe microphone installed in a ‘laminarised’ boom projecting from the fin of the aircraft. As the signal associated with the windmilling turbines was predominant even at flight speeds near the aircraft's limiting Mach number, it was not possible to relate the noise radiated from the turbulent boundary layers to flight speed. The measured sound pressure levels in the frequency band 4o c/s to 15 kc/s, for Mach numbers between 0.24 and 0.66 at an altitude of 20,000 ft., were in the range from 110 to 115 decibels relative to 0.0002 ubar. A calculation of the radiated noise from the boundary layers gave overall levels of 85 to 120 db relative to 0.0002 bar at the microphone position on the aircraft for the same range of flight conditions.Item Open Access Pressure and boundary layer measurements on a tapered swept wing in flight(College of Aeronautics, 1960-03) Hyde, D.Pressure and boundary layer measurements were made in flight on a full scale swept half-wing mounted as a dorsal fin on the mid fuselage of an. Avro Lancaster aircraft. A Reynolds Number range of 0.88 x 106 to 1.86 x 106 per foot was available. The tapered wing had a semi-span of 102.5 ins. and an aspect ratio of 2.87; the quarter chord sweep was 40o and the symmetrical section was RAE 102, of 8% thickness/chord ratio along wind. Comprehensive static pressure measurements were recorded over a nominal incidence range of 0o to 10o. At mid semi-span and zero incidence, the measured chordwise pressure distribution compared well with theory. The non-dimensional chordwise and spanwise loadings were in close agreement with Kuchemann' s predictions, but the experimental lift curve slope was 6% greater than the theoretical value. From the boundary layer results the positions of the transition fronts were deduced. No laminar flow was obtained on either surface at the highest Reynolds number of 1.86 x 106 per foot, or at incidences of 6° and greater at all test Reynolds numbers. The secondary flow Reynolds number corresponding to the onset of sweep instability was found to be in the range 80 < N < 133; Owen's predicted critical value is 125.