Acoustical Flight Test of the Piper Lance

Research is being conducted by the Federal Aviation Administration (FAA) and other members of the International Civil Aviation Organization (ICAO) toward refinement of current noise regulation of propeller-driven small airplanes. These studies are examining the prospect of substituting a takeoff procedure of equal stringency for the level flyover certification test presently required. It was initially assumed that equivalency could be established between the takeoff and level flyover procedures via adjustment equations involving propeller helical-tip Mach number and noise propagation distance to account for differences in airspeed and altitude respectively. However, as test results became available, it was found that the propeller helical-tip Mach number adjustment equation did not adequately account for the measured noise level differences between the takeoff and level flyover procedure. After applying the adjustment equations, the takeoff noise levels were 3 to 4 decibels higher than the level flyover noise levels. This effect is believed to result from unsteady propeller blade loading when the aircraft is in a pitch-up position during a takeoff/climbout as opposed to level flight. The test aircraft was a Piper Cherokee Lance (PA-32R-300) equipped with a two-blade speed propeller. The objective required a series of flights ranging from level flyover to a takeoff/climbout performed at Vx (speed for best angle climb). Noise level versus propeller inflow angle was addressed by a series-to-series variation of aircraft speed at constant power and revolutions per minute (RPM). Since airspeed is a component of the helical-tip Mach number (MH) and given the generally strong influence of MH on noise levels, additional series of overflights were necessary to empirically relate MH to the noise levels actually produced by the Lance. The MH issue was addressed through a series-to-series variation of propeller RPM at constant power and airspeed.


  • English

Media Info

  • Media Type: Digital/other
  • Edition: Final Report
  • Features: Appendices; Figures; Photos; References; Tables;
  • Pagination: 114p

Subject/Index Terms

Filing Info

  • Accession Number: 01496730
  • Record Type: Publication
  • Report/Paper Numbers: DOT/FAA/EE-86/9
  • Created Date: Oct 28 2013 9:47AM