ASWING Overview

Summary Description

Configuration Description

• Interconnected nonlinear beams
  • Representing...
    • lifting surfaces, or
    • slender bodies
  • Specified by...
    • geometry
    • mass and inertia distributions
    • structural stiffness and damping distributions
    • aerodynamic properties
    • control surface influence distributions
• Point objects with...
  • mass
  • angular momentum
  • drag area
  • volume
• External struts
• Engines with...
  • applied forces
  • applied moments
  • simple or advanced powerplant model
• Control surfaces on beams, influencing...
  • section CL
  • section CM
• General extended lifting-line 3D aero representation, with...
  • wind-aligned trailing vorticity
  • wind-aligned Prandtl-Glauert compressibility treatment
  • local shed-vorticity unsteady flow model
  • section-stall lift limiting
  • section-stall profile drag model

Solution state for all analyses

• beam deflections, angles (fully nonlinear)
• beam loads, bending moments (general nonlinear 6-d.o.f. beam)
• beam velocities, rotation rates (local)
• circulation distributions on surface beams
• aircraft position, orientation angles
• aircraft velocities and rotation rates
• aircraft accelerations and angular accelerations
• control deflections (aerodynamic surfaces, engine power settings)

Analysis Capabilities

• Nonlinear static response, with arbitrary flight state specification
  • direct: specified angles, rates, control deflections
  • indirect: specified forces, moments, trim states
• Nonlinear dynamic response (time domain)
  • with or without arbitrary gust field
  • with or without arbitrary control forcing
  • with or without user-defined control law
  • evaluation via...
    • frame-by-frame plotting of all state quantities
    • aircraft-motion "movie"
• Linear dynamic response about nonlinear state (frequency domain)
  • due to...
    • Initial conditions,
    • Control forcing,
    • Gust velocity field
  • evaluation via...
    • Bode plots
    • Motion and deformation response "movie"
    • Aero load response displays
    • Structural load and deformation response displays
• Eigenmode analysis
  • user-defined control law can participate (closed-loop stability)
  • entire frequency spectrum captured...
    • ..flight stability (lowest frequencies)
    • ..flutter stability (higher frequencies)
    • evaluation via...
      • Root maps
      • Motion and deformation eigenmode "movie"
      • Aero load eigenmode displays
      • Structural load and deformation eigenmode displays
    • Reduced Order Model construction based on selected eigenmodes
    • ROM matrix output for control law design, fast response analyses

Frequently Asked Questions

Announcements

• A Polish translation of this page
  has been created by Valeria Aleksandrova.

Software

Documents

• Theory document.
  asw_theory.ps (1061 Kb).
  asw_theory.pdf (420 Kb).
  
• Unsteady extension theory document.
  asw_uns_theory.ps (780 Kb).
  asw_uns_theory.pdf (330 Kb).
  
• Paper AIAA 99-1394, "Integrated Simulation Model for Preliminary Aerodynamic, Structural, and Control-Law Design of Aircraft."
  (condensed form of theory documents with a few application examples)
  asw_aiaa.ps (1520 Kb).
  asw_aiaa.pdf (460 Kb).
  
• Plain text version of User Guide.
  aswing_doc.txt
  
• ASWING runtime data flow organization. More detailed version of ASCII figure in User Guide.
  dataflow.ps
  dataflow.pdf
• Summary of changes made for recent ASWING versions.
  version_notes.txt

Sample Input Files, Calculations

• Daedalus Human-Powered-Airplane.
  • Input file: dae.asw
  • Bode responses to rudder forcing: PDF plot
  • Response to 0.2 Hz rudder forcing, nearly rigid motion: (animated GIF, 4.1 MB)
  • Response to 1.0 Hz rudder forcing, reduced response due to tailboom compliance: (animated GIF, 6.0 MB)
  
  
• Ultralight Sailplane.
  • Input file: usa.asw
  • Specified vertical gust field: PDF plot
  • Nonlinear time-march solution: Vertical gust under left wing (animated GIF, 1.4 MB)
  
  
• Flying-Wing UAV
  • Input file: fw.asw
  • Eigenmode root progression with airspeed, showing Body Freedom Flutter (BFF) mode going unstable: PDF plot
  • Unstable BFF eigenmode movie: BFF mode (animated GIF, 2.3 MB)
  • BFF destroying a UAV, on YouTube: SAE Aero Design 2007 - Flutter
  • Another BFF incident, on YouTube (flutter is at 3:30, slo-mo replay at 4:05): Horten Maiden Flight
  
  
• Discus Launch Glider (DLG)
  • Time-march aeroelastic simulations of Supergee-II DLG launch. Release is at frame 60/200.
    External View (animated GIF, 1.2 MB)
    Aero loads and twist (animated GIF, 3.7 MB)
    Torsion shear stresses, Bending extensional strains (animated GIF, 3.3 MB)
  
  
• Oddball Stuff
  • Time-march aeroelastic simulation of flapping bird: Falcon (animated GIF, 1.35 MB)

Author: Mark Drela, drela (AT) mit (DOT) edu

Page Revisions

January 11, 2001
- Page created. ASWING 5.42

November 22, 2005
- ASWING 5.62
- Added the Sensor entity, which delivers state outputs
- Added 2D-Bode frequency gust analysis
- Added more general engine model capability
- Added propeller plume model
- Added structural damping
- Added Reduced Order Modeling capability
- ... and a bunch of other stuff. See version_notes.txt

July 17, 2005
- Added link to dataflow.ps file.

March 10, 2007
- ASWING 5.64
- Further additions to the Reduced Order Modeling stuff.
- ... See version_notes.txt

March 13, 2007
- Added PDF versions of PS documents

October 25, 2007
- ASWING 5.73
- Added gust response info to the ROM output
- Added ground effect
- ... See version_notes.txt
- Updated the theory documentation

May 29, 2008
- ASWING 5.79
- Posted sample input files above
- Lots of minor tweaks -- see version_notes.txt

August 4, 2008
- Reorganized and updated the ASWING description above

September 2, 2008
- ASWING 5.82
- Added prop whirl flutter prediction capability, for 3 or more prop blades.
- Added moment/angle compliance option to the beam joint equations.
- Updated the Steady and Unsteady theory documents.
- Other minor tweaks -- see version_notes.txt

November 25, 2008
- Added a FAQ file link above

June 12, 2009
- Replaced moving GIFs with clearer versions

February 1, 2010
- Added YouTube link to BFF video
- Added animated GIFs for DLG launch
- Added animated GIF for flapping bird