References

Back to the FDM homepage

1. Cooke, Zyda, Pratt, and McGhee, "NPSNET: Flight Simulation Dynamic Modeling Using Quaternions", Presence, Vol. 1, No. 4, pp. 404-420 Naval Postgraduate School, January 1994
2. D. M. Henderson, "Euler Angles, Quaternions, and Transformation Matrices", JSC 12960, July 1977
3. Richard E. McFarland, "A Standard Kinematic Model for Flight Simulation at NASA-Ames", NASA CR-2497, January 1975
4. In-Flight Simulation Studies at the NASA Dryden Flight Research Facility (NASA, pdf file)
5. Flight-Determined Subsonic Lift and Drag Characteristics of Seven Lifting-Body and Wing-Body Reentry Vehicle Configurations with Truncated Bases (AIAA, pdf file)
6. A Correlation Between Flight-Determined Derivatives and Wind-Tunnel Data for the X-24B Research Aircraft (NASA, pdf file)
7. SpaceLink: Next Generation and Experimental Aircraft
8. Wingless Flight
9. Testing the Lifting Bodies at Edwards
10. Coupling Dynamics in Aircraft: A Historical Perspective
11. A Model for Space Shuttle Orbiter Tire Side Forces Based on NASA Landing Systems Research Aircraft Test Results
12. Simulator Evaluation of Simplified Propulsion-Only Emergency Flight Control Systems on Transport Aircraft
13. Aviation Formulary (Aviation Formulas)
14. Helicopter Aviation Pages at MIT
15. Barnes W. McCormick, "Aerodynamics, Aeronautics, and Flight Mechanics", Wiley & Sons, 1979 ISBN 0-471-03032-5
16. Bernard Etkin, "Dynamics of Flight, Stability and Control", Wiley & Sons, 1982 ISBN 0-471-08936-2

FlightGear in the Press

1. Interview with Curt Olson at Avsim.Com
2. Review of FlightGear at Skymasters Aviation

Set of Stability Derivatives for FGAircraft class

The aerodynamic coefficients used in this model are:

Longitudinal
  C_l0 - Reference lift at zero alpha
  C_d0 - Reference drag at zero alpha
  C_la - Lift curve slope (w.r.t. alpha)
  C_da - Drag curve slope (w.r.t. alpha)
  C_lq - Lift due to pitch rate
  C_ladt - Lift due to alpha rate

  C_madt - Moment due to alpha rate
  C_m0 - Reference moment at zero alpha
  C_ma - Pitching moment slope (w.r.t. alpha)

Lateral
  C_yb - Side force due to sideslip
  C_yr - Side force due to yaw rate

  C_lb - Dihedral effect (roll moment due to sideslip)
  C_lp - Roll damping (roll moment due to roll rate)
  C_lr - Roll moment due to yaw rate
  C_nb - Weathercocking stability (yaw moment due to sideslip)
  C_np - Rudder adverse yaw (yaw moment due to roll rate)
  C_nr - Yaw damping (yaw moment due to yaw rate)

Control
  C_lde - Lift due to elevator
  C_dde - Drag due to elevator
  C_ydr - Side force due to rudder

  C_mde - Pitch moment due to elevator
  C_lda - Roll moment due to aileron
  C_ndr - Yaw moment due to rudder
  C_nda - Yaw moment due to aileron

Flight Dynamics Model Class [Re-]Design

The purpose of this page is to present a possible object oriented framework for the FGFS Flight Dynamics Model. The name JSBSim seems to have stuck, so that's what I will call it. It is based on the references mentioned at the bottom of this document, as well as on LaRCsim, the current FDM driving FlightGear.

Four classes comprise the bulk of the FDM in this scheme: FGState - Holds all global state variables as well as convenience methods such as Reset(), et. al. FGAircraft - "Container" class for the aircraft. Has methods FAero(), FMass(), FProp(), FGear(), MAero(), MMass()etc.This class will contain only aircraft unique functionality. This class will also have subclasses, helper classes: FGCoefficient, for one. FGFDMExec - Schedules execution of the models. This class is controlled by the simulation itself. FGFDMExec controls whether this class is executing or not, the integration rate, etc. An example of a method within this class is Run(). FGModel: From this class the following models will be derived: FGAtmosphere FGAuxiliary FGFCS (flight controls)   - FGFilter (for lag, lead-lag, hi/lo pass, etc. for closed loop control systems) FGTranslation FGRotation FGPosition FGUtility - Contains utility routines

Glossary of Acronyms and Terms

FDM - Flight Dynamics Model
FDMG - FDM Group
FLCS - FLight Control System
DFLCS - Digital FLCS
CFD - Computational Fluid Dynamics

Stability Derivatives for a typical airliner:

· Longitudinal
Mach Alt CL CD CLa CDa Cma CLadot CLq
.25 SL 1.11 0.102 5.70 0.66 -1.26 6.7 5.4
.9 40k 0.5 0.042 5.5 0.47 -1.6 0.006 6.58
 
Mach CMq CLM CDM CmM CL-De CM-De
.25 -20.8 -0.81 0.0 0.27 0.338 -1.34
.90 -25.0 0.2 0.25 -0.10 0.3 -1.2 
· Lateral
Mach Alt CyB ClB CnB Clp Cnp Clr Cnr
.25 SL -0.96 -0.221 0.150 -0.45 -0.121 0.101 -0.30
.90 40k -0.85 -0.10 0.20 -0.30 0.20 0.20 -0.325
 
Mach Cl-Da Cn-Da Cy-Dr Cl-Dr Cn-Dr
.25 0.0461 0.0064 0.175 0.007 -0.109
.90 0.014 0.003 0.075 0.005 -0.09
 
W = 636,600 lb
CG @ 25%MAC
S = 5500 ft sq
b = 195.68 ft sq
c-bar = 27.31 ft
Ix 18.2 E6 slug-ft sq
Iy 33.1 E6 slug-ft sq
Iz 49.7 E6 slug-ft sq
Ixz 0.97 E6 slug-ft sq
 
All derivatives are per radian.
For more aircraft models, check out the following references: 

1. Robert K. Heffley and Wayne F. Jewell, Aircraft Handling Qualities Data, NASA CR 2144, December 1972, 343 pp. Aircraft described are NT-33A, F-104A, F-4C, X-15, HL-10, Lockheed jetstar, Convair 880M, B-747, C-5A, and XB-70A.

2. G. L. Teper, "Aircraft Stability and Control Data, NASA CR-96008, 1969. Aircraft covered are A-7A, A-4D, F-106B, T-38, F-5A, F-104, F-105B, B-58, Navion, and DC-8.

Site curator: Jon S. Berndt
Created: 21 March 2000
Last updated: 01/07/2001 09:35 PM