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Structures and Materials Division Research and Technology Directorate NASA Glenn Research Center

Tribology and mechanical Components Branch
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Aero Drive Systems - High Speed Gear Lubrication and Efficiency
Research Objectives
Develop an understanding of the thermal behavior of high speed gear systems operating in normal and emergency lubrication conditions and experimentally validate and develop analytical tools to predict their normal operational characteristics including performance and efficiency.
Technical Challenges
  • Gear design, shrouding, and lubrication system parameters influence the normal performance and efficiency of a gear system
  • Operational conditions imposed on the helical gear train and gear system type can have a drastic effect on performance
  • Windage has been shown to be a substantial part of overall gear system losses when dealing with high pitch line velocities (>15,000 ft/min). Windage is the work that the gear system does on the air-lubricant environment inside the gear box.
  • The open literature has very limited amount of data, empirical methods, or analytical development on gear windage.
Current Research
With the cooperation of Bell Helicopter, researchers at NASA Glenn Research Center have been testing different gear designs and configurations to determine their effect on overall high speed helical gear train performance. Extensive instrumentation is used to measure thermal behavior in a relevant rotorcraft environment and comparisons are made. Work has also begun on a facility dedicated to understanding the gear windage mechanism.

High speed helical gear train
Above: High speed helical gear train.

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Dr. Robert Handschuh
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Last Updated: April 21, 2009