User's Guide for the NREL Teetering Rotor Analysis Program (STRAP)

Research output: NRELTechnical Report


This Report gives the reader an overview of and instructions on the proper use of the National Renewable Energy Laboratory (formerly the Solar Energy Research Institute, or SERI) Teetering Rotor Analysis Program (STRAP version 2.2). STRAP is a derivative of the Force and Loads Analysis Program (FLAP). It is intended as a tool for prediction of rotor and blade loads and response for onlytwo-bladed teetering hub wind turbines. The effects of delta-3, undersling, hub mass, and wind turbulence are accounted for. The objectives of this report are to give an overview of the code and also show the methods of data input and correct code execution steps in order to model an example two-bladed teetering hub turbine. A large portion of the discussion (Sections 6.0, 7.0, and 8.0) isdevoted to the subject of inputting and running the code for wind turbulence effects. The ability to include turbulent wind effects is perhaps the biggest change in the code since the release of FLAP version 2.01 in 1988. This report is intended as a user's guide. It does not contain a theoretical discussion on equations of motion, assumptions, underlying theory, etc.
Original languageAmerican English
Number of pages213
StatePublished - 1992

NREL Publication Number

  • NREL/TP-257-4671


  • computer codes
  • loads
  • structures
  • wind turbines


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