The various aspects of engine starting are discussed and it is shown that the dominant factor controlling start characteristics at sub-zero ambient temperatures is lubricant viscous shear effects. The magnitude of this effect is such that stored energy start system weights for rapid starting of small aircraft auxiliary power units may weigh as much as the power unit itself. The same auxiliary power units, if used as starters for larger main propulsion gas turbines, are burdened with the incompatibility of torque output dependent upon air density, yet main engine cranking torque is dependent basically upon lubricant viscosity. It is concluded that start system over-design philosophy will tend to persist pending the application of external starting torque directly to the high speed shaft itself with uncoupling of all but necessary viscous parastic shear sources, or until detailed research and development are devoted in applied tribology to further reduce viscous shear effects in high speed turbo-machinery.

  • Supplemental Notes:
    • Paper for the 6-8 August 1979 Meeting.
  • Corporate Authors:

    American Society of Mechanical Engineers

    Two Park Avenue
    New York, NY  United States  10016-5990
  • Authors:
    • Rodgers, C
  • Publication Date: 1979

Media Info

  • Features: References;
  • Pagination: 8 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00301365
  • Record Type: Publication
  • Source Agency: Engineering Index
  • Report/Paper Numbers: 79-GT-95 Conf Paper
  • Files: TRIS
  • Created Date: Feb 11 1980 12:00AM