Marchetti S-211 -- Linear Model

Graduate Research done by Jeff Scott
Advisor: Prof. Michael Selig
Applied Aerodynamics Group
Department of Aeronautical and Astronautical Engineering
University of Illinois at Urbana-Champaign, Urbana, Illinois 61801

Last updated June 7, 2000

The linear aerodynamics model uses stability derivatives to approximate actual aircraft behavior. The Marchetti S-211 linear model is based on the following flight conditions (cruise 1):

Flight Conditions
Variable Variable
in Code 		Description Units Value(s) Source Notes
h Altitude altitude above sea level ft 25000 Roskam pg 494
Alpha angle of attack deg 0 Roskam pg 494
V V_true_kts velocity (true air speed) kts 361.2 Roskam pg 494 Mach 0.6
q Dynamic_pressure dynamic pressure lb/ft2 198.0 Roskam pg 494
C.G. - center of gravity location % 25 Roskam pg 494
CL CL lift coefficient - ? not available
CD CD drag coefficient - ? not available
Cm Cm pitching moment coefficient - ? not available

The data input into the simulator is listed in the following tables:

Geometry
Variable Variable
in Code 		Description Units Value(s) Source Notes
b bw wingspan ft 26.3 Roskam pg 494
cbar wing mean aerodynamic chord ft 5.4 Roskam pg 494
S Sw wing surface area ft2 136 Roskam pg 494

Control Surface Geometry
Variable Variable
in Code 		Description Units Value(s) Source Notes
emax demax maximum elevator deflection deg +20 - guess
emin demin minimum elevator deflection deg -20 - guess
amax damax maximum aileron deflection deg +20 - guess
amin damin minimum aileron deflection deg -20 - guess
rmax drmax maximum rudder deflection deg +20 - guess
rmin drmin minimum rudder deflection deg -20 - guess

Mass Data
Variable Variable
in Code 		Description Units Value(s) Source Notes
W Weight weight at flight condition lb 4000 Roskam pg 494 converted to Mass
[slug/ft3] in code
Ixx I_xx roll inertia slug ft2 800 Roskam pg 494
Iyy I_yy pitch inertia slug ft2 4800 Roskam pg 494
Izz I_zz yaw inertia slug ft2 5200 Roskam pg 494
Ixz I_xz lateral cross inertia slug ft2 200 Roskam pg 494

Propulsion Data
Variable Variable
in Code 		Description Units Value(s) Source Notes
Tmax simpleSingleMaxThrust maximum thrust lb 600 Roskam pg 495 estimated from CTx
at cruise 1
Tmax simpleSingleMaxThrust maximum thrust lb 2500 David pg 801 engine rating

Aerodynamic Data
Variable Variable
in Code 		Description Units Value(s) Source Notes
CD0 CDo drag coefficient at =0 - 0.0205 Roskam pg 495
CD CD_a drag curve slope 1/rad 0.12 Roskam pg 495
CDe CD_de drag due to elevator 1/rad 0 Roskam pg 495 e positive down
CL0 CLo lift coefficient at =0 - 0.149 Roskam pg 495
CL CL_a lift curve slope 1/rad 5.5 Roskam pg 495
CL CL_adot lift due to angle of attack rate 1/rad 4.2 Roskam pg 495
CLq CL_q lift due to pitch rate 1/rad 10.0 Roskam pg 495
CLe CL_de lift due to elevator 1/rad 0.38 Roskam pg 495 e positive down
Cm0 Cmo pitch moment coefficient at =0 - -0.08 Roskam pg 495
Cm Cm_a pitch moment due to angle of attack 1/rad -0.24 Roskam pg 495
Cm Cm_adot pitch moment due to angle of attack rate 1/rad -9.6 Roskam pg 495
Cmq Cm_q pitch moment due to pitch rate 1/rad -17.7 Roskam pg 495
Cme Cm_de pitching moment due to elevator 1/rad -0.88 Roskam pg 495 e positive down
CY CY_beta side force fue to sideslip angle 1/rad -1.0 Roskam pg 496
CYp CY_p side force due to roll rate 1/rad -0.14 Roskam pg 496
CYr CY_r side force due to yaw rate 1/rad 0.61 Roskam pg 496
CYa CY_da side force due to aileron 1/rad 0 Roskam pg 496 a positive
right aileron up
CYr CY_dr side force due to rudder 1/rad 0.028 Roskam pg 496 r positive left
Cl Cl_beta dihedral effect 1/rad -0.11 Roskam pg 496
Clp Cl_p roll damping 1/rad -0.39 Roskam pg 496
Clr Cl_r roll moment due to yaw rate 1/rad 0.28 Roskam pg 496
Cla Cl_da roll moment due to aileron 1/rad -0.10 Roskam pg 496 a positive
right aileron up
Clr Cl_dr roll moment due to rudder 1/rad 0.05 Roskam pg 496 r positive left
Cn Cn_beta weathercock stability 1/rad 0.17 Roskam pg 496
Cnp Cn_p adverse yaw 1/rad 0.09 Roskam pg 496
Cnr Cn_r yaw damping 1/rad -0.26 Roskam pg 496
Cna Cn_da yaw moment due to aileron 1/rad 0.003 Roskam pg 496 a positive
right aileron up
Cnr Cn_dr yaw moment due to rudder 1/rad -0.12 Roskam pg 496 r positive left

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