#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ # # Aircraft: # # A-4D Skyhawk # Attack Bomber # # File # a4-v1-nl (version 1, non-linear model) # # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ # # Authors: # # Michael Selig # http://www.uiuc.edu/~m-selig # # 2002/12/14 Initial workup # 2003/05/22 First post to FlightGear base package # # #~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ # # Notes: # # [1] This file is setup for the sea level, subsonic M = 0.4, trim case # (no Mach effects are included) # # [2] To approximate the CSS (control stick steering mode) of the AFCS # of the A4, a SAS has been included in this model. # # - Additional models and updates # http://www.aae.uiuc.edu/m-selig/apasim.html # #~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ # # Specs # # - Max roll rate is approximately 400 deg/sec # http://www.airbum.com/pireps/PirepA4.html # - 6g max load for trainer # http://www.airwarbirds.com/ta-4j_specs.htm # - Maximum speed: 586 knots (with a 4,000 pound bomb load) # presumably @ max gross weight and sea level # - Initial climb rate: 8,440 ft/min # # Information Sources # # [1] Robert C. Nelson, Flight Stability and Automatic Control, 2nd ed. # McGraw-Hill, 1998 # [2] NATOPS Flight Manual, Navy Model A-4C/L Aircraft # NAVAIR 01-40AVE-1, Jan 1973 # [3] http://www.aerospaceweb.org/aircraft/attack/index.shtml # [4] http://www.airbum.com/pireps/PirepA4.html #~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ # todo # [] update the gear gear_rate line when we do re-org in input file reader # [] update downwash terms #~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ # various "init" settings init use_V_rel_wind_2U init use_dyn_on_speed_curve1 init dyn_on_speed 2 init dyn_on_speed_zero 1 init use_Alpha_dot_on_speed 7 # [ft/sec] speed below which Alpha_dot is set to zero init use_gamma_horiz_on_speed 15 # [ft/sec] speed above which gamma-horiz-deg is used in chase view # geometry geometry bw 27.5 # [ft] [x] Ref [1] geometry cbar 10.8 # [ft] [x] Ref [1] geometry Sw 260 # [ft^2] [x] Ref [1] # control surface deflections # Horizontal stab deflection information from Roskam Part III # Stab deflection: +4 deg (nose up), -12 deg (nose down) # Elevator deflection: +25.5 (nose up), -15.5 (nose down) # Vertical stab: +-24.5 controlSurface de 25.5 15.5 # [deg] [x] See above controlSurface da 25 25 # [deg] [x] See above controlSurface dr 24.5 24.5 # [deg] [x] See above controlSurface flap_max 50 # [deg] [x] From POH Ref [2] controlSurface flap_rate 10 # [deg/sec] rate of flap deflection movement once commanded to move # SAS data controlSurface use_aileron_sas_type1 controlSurface aileron_sas_KP 0.3 controlSurface aileron_sas_max 7 # [deg] controlSurface use_elevator_sas_type1 controlSurface elevator_sas_KQ 0.25 controlSurface elevator_sas_max 5 # [deg] controlSurface elevator_sas_min -5 # [deg] controlSurface use_rudder_sas_type1 controlSurface rudder_sas_KR 3 # mass and moment of inertia data mass Weight 17578 # [lb] [x] Ref [1] mass I_xx 8090 # [slug-ft^2] [x] Ref [1] mass I_yy 25900 # [slug-ft^2] [x] Ref [1] mass I_zz 29200 # [slug-ft^2] [x] Ref [1] mass I_xz 1300 # [slug-ft^2] [x] Ref [1] # Wright J65-W-20 8300 lb static thrust, turbojet #engine simpleSingleModel 8500 -31 920 # [lb] [lb/fps] [ft/sec] #engine simpleSingleModel 11500 -31 920 # [lb] [lb/fps] [ft/sec] engine simpleSingleModel 13000 -31 1120 # [lb] [lb/fps] [ft/sec] # where token3 - static thrust in [lb] # token4 - slope dT/dV at the speed at which thrust goes to zero [lb/fps] # token5 - speed at which thrust goes to zero [ft/sec] init downwashMode 100 init downwashCoef 0.040 # [1/ft] [ ] Needs update ###################### # Longitudinal terms # ###################### # Lift data #CL CLo 0.28 # [/rad] [x] Ref [1] #CL CL_a 3.45 # [/rad] [x] Ref [1] CL CLfa CLfa.dat 0 1 # [x] see a4 notes p 2, replaces CLo and Cl_a above CL CL_adot 0.72 # [/rad] [x] lift due to alfa_dot, Ref [1] CL CL_q 0.12 # [/rad] [x] lift due to pitch rate, based on Marchetti jet trainer CL CL_de 0.36 # [/rad] [x] lift due to elevator deflection, Ref [1] CL CL_df 0.4 # [ ] estimate # parasite drag polar from +-180 deg for wing and tail CD CDo 0.015 # [] zero lift parasite drag, based partly on CD_a, see a4 notes 021215 CD CD_de 0.0002 # [] estimate (is too small) # Induced drag #CD CD_a 0.3 # [-] [x] drag due to angle of attack, Ref [1] CD CDK 0.144 # [-] [x] See A4 notes p 2 021215, replaces CD_a above CD CD_df 0.010 # [/rad] [ ] estimate CD CD_dg 0.005 # [-] [ ] estimate # wing/fuse moment curve from +-180 deg #Cm Cm_a .1326 # [/rad] [x] fuselage and wing contribution, Ref [1] #Cm Cm_de -0.5 # [/rad] [x] moment due to elevator deflection, Ref [1] Cm Cmo -.0115 # [-] [x] trim condition Cm Cmfa Cmfa.dat 0 1 # [-] [x] trim condition Cm Cmfade Cmfade.dat 0 1 1 # [-] [x] relaces Cm_a and Cm_de above Cm Cm_q -3.6 # [/rad] [x] moment due to pitch rate, Ref [1] Cm Cm_adot -1.1 # [/rad] [x] moment due to alfa_dot, Ref [1] ########################### # Lateral Direction terms # ########################### # rudder dr terms # convention: positive for trailing edge left (nose left) # this is same as Ref [1] CY CY_dr 0.17 # [/rad] [x] side force due to rudder deflection, Ref [1] #Cl Cl_dr -0.105 # [/rad] [x] roll moment due to rudder deflection, Ref [1] is buggy Cl Cl_dr 0.02 # [/rad] [x] roll moment due to rudder deflection, fixes Ref [1] #Cn Cn_dr -.032 # [/rad] [x] yaw moment due to rudder deflection, Ref [1] is buggy Cn Cn_dr -.11 # [/rad] [x] yaw moment due to rudder deflection, fixes Ref [1] # yaw rate r terms CY CY_r 0.028 # [/rad] [] side force due to yaw rate, placeholder based on Marchetti Cl Cl_r 0.14 # [/rad] [x] roll moment due to yaw rate, Ref [1] Cn Cn_r -0.35 # [/rad] [x] yaw moment due to yaw rate (damping), Ref [1] # beta terms CY CY_beta -0.98 # [/rad] [x] side force due to yaw, Ref [1] Cl Cl_beta -0.12 # [/rad] [x] roll moment due to yaw, Ref [1] Cn Cn_beta 0.25 # [/rad] [x] yaw moment due to yaw, Ref [1] # aileron da terms # convention: positive for right aileron trailing edge down, left aileron trailing edge up (bank left) # this is opposite Ref [1] #CY CY_da 0.0 # [/rad] nothing given in Ref [1] Cl Cl_da -0.08 # [/rad] [x] roll moment due to aileron, Ref [1] Cn Cn_da -0.06 # [/rad] [x] yaw moment due to aileron, Ref [1] # roll rate p terms #CY CY_p 0.0 # [/rad] nothing given in Ref [1] Cl Cl_p -0.26 # [/rad] [x] roll moment due to roll rate (damping), Ref [1] Cn Cn_p 0.022 # [/rad] [x] yaw moment due to roll rate, Ref [1] #gear gear_max 1 gear gear_rate .333 # [unit-norm/sec] retracts gear in 3 sec # nose wheel (must be position 0 if present) gear Dx_gear 0 10.2 # x-offset from CG [ft] gear Dy_gear 0 0 # y-offset from CG [ft] gear Dz_gear 0 8.2 # z-offset from CG [ft] gear cgear 0 2000 # damping [lbs/ft/sec] gear kgear 0 4000 # springiness [lbs/ft] gear muGear 0 0.01 # rolling coefficient gear strutLength 0 -.5 # gear travel [ft] (not yet used) # right gear (must be position 1 if present) gear Dx_gear 1 -3. # [ft] gear Dy_gear 1 5. # [ft] gear Dz_gear 1 7.3 # [ft] gear cgear 1 4000 # [lbs/ft/sec] gear kgear 1 8000 # [lbs/ft] gear muGear 1 0.01 # rolling coefficient gear strutLength 1 -.5 # gear travel [ft] (not yet used) # left gear (must be position 2 if present) gear Dx_gear 2 -3. # [ft] gear Dy_gear 2 -5. # [ft] gear Dz_gear 2 7.3 # [ft] gear cgear 2 4000 # [lbs/ft/sec] gear kgear 2 8000 # [lbs/ft] gear muGear 2 0.01 # rolling coefficient gear strutLength 2 -.5 # gear travel [ft] (not yet used) # right wing gear Dx_gear 3 -1. # [ft] gear Dy_gear 3 14. # [ft] gear Dz_gear 3 2.2 # [ft] gear cgear 3 2500 # [lbs/ft/sec] gear kgear 3 5000 # [lbs/ft] gear muGear 3 0.01 # rolling coefficient gear strutLength 3 -.5 # gear travel [ft] (not yet used) # left wing gear Dx_gear 4 -1. # [ft] gear Dy_gear 4 -14. # [ft] gear Dz_gear 4 2.2 # [ft] gear cgear 4 2500 # [lbs/ft/sec] gear kgear 4 5000 # [lbs/ft] gear muGear 4 0.01 # rolling coefficient gear strutLength 4 -.5 # gear travel [ft] (not yet used) # ahead and above nose gear Dx_gear 5 13. # [ft] gear Dy_gear 5 0. # [ft] gear Dz_gear 5 -6. # [ft] gear cgear 5 1000 # [lbs/ft/sec] gear kgear 5 2000 # [lbs/ft] gear muGear 5 0.01 # rolling coefficient gear strutLength 5 -.5 # gear travel [ft] (not yet used) # nose gear Dx_gear 6 13. # [ft] gear Dy_gear 6 0. # [ft] gear Dz_gear 6 4. # [ft] gear cgear 6 1500 # [lbs/ft/sec] gear kgear 6 3000 # [lbs/ft] gear muGear 6 0.01 # rolling coefficient gear strutLength 6 -.5 # gear travel [ft] (not yet used) # tail skid gear Dx_gear 7 -18. # [ft] gear Dy_gear 7 0. # [ft] gear Dz_gear 7 2.5 # [ft] gear cgear 7 1500 # [lbs/ft/sec] gear kgear 7 3000 # [lbs/ft] gear muGear 7 0.01 # rolling coefficient gear strutLength 7 -.5 # gear travel [ft] (not yet used) # ahead of left wing gear Dx_gear 8 18. # [ft] gear Dy_gear 8 14. # [ft] gear Dz_gear 8 1.2 # [ft] gear cgear 8 500 # [lbs/ft/sec] gear kgear 8 1000 # [lbs/ft] gear muGear 8 0.01 # rolling coefficient gear strutLength 8 -.5 # gear travel [ft] (not yet used) # ahead of right wing gear Dx_gear 9 18. # [ft] gear Dy_gear 9 14. # [ft] gear Dz_gear 9 1.2 # [ft] gear cgear 9 500 # [lbs/ft/sec] gear kgear 9 1000 # [lbs/ft] gear muGear 9 0.01 # rolling coefficient gear strutLength 9 -.5 # gear travel [ft] (not yet used) record debug5 *