Non linear control polars

The type 6 “Control polar” has been added in flow5 for increased versatility, to allow analysis of the sensitivity to various design parameters, and to enable the implementation of viscous loops.

This new T6 polar supersedes and replaces the former T4 (fixed a.o.a.) and T5 (sideslip) polars.

Control parameters

The analysis of T6 polars is performed for a specified range of design parameters which are

  • operating angles: angle of attack, sideslip, and bank angle
  • velocity range
  • wing and fuselage tilt angles
  • inertia parameters: mass and CoG position

More parameters such as wing area, aspect ratio, average twist and sweep will be included in a future release.

See this video for more information.

Viscous loop

The analysis of T6 polars can be conducted linearly as in xflr5. However, for increased accuracy, a viscous loop is also available. It uses the “virtual twist” method described in “Computationally Efficient Transonic and Viscous Potential Flow Aero-Structural Method for Rapid Multidisciplinary Design Optimization of Aeroelastic Wing Shaping Control”, by Eric Ting and Daniel Chaparro, Intelligent Systems Division, NASA Ames Research Center.
The philosophy behind this method is similar to the non-linear LLT, with comparable results. Preliminary testing has shown that the method is robust and converges handily.

See this video for more information.