Convair 880 -- 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 1, 2000

The linear aerodynamics model uses stability derivatives to approximate actual aircraft behavior. The Convair 880 linear model is based on the following flight conditions (cruise condition 6 in McCormick):

Flight Conditions
Variable Variable
in Code 		Description Units Value(s) Source Notes
h Altitude altitude above sea level ft 35000 McCormick pg 624
Alpha angle of attack deg 4.7 McCormick pg 624
V V_true_kts velocity (true air speed) kts 461 McCormick pg 624 Mach 0.8
q Dynamic_pressure dynamic pressure lb/ft2 223.7 -
C.G. - center of gravity location % 25 McCormick pg 624
CL CL lift coefficient - 0.347 McCormick pg 624
CD CD drag coefficient - 0.024 McCormick pg 624
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 120 Nelson pg 414
cbar wing mean aerodynamic chord ft 18.94 Nelson pg 414
S Sw wing surface area ft2 2000 Nelson pg 414

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 155000 McCormick pg 624 converted to Mass
[slug/ft3] in code
Ixx I_xx roll inertia slug ft2 1510000 McCormick pg 624
Iyy I_yy pitch inertia slug ft2 2510000 McCormick pg 624
Izz I_zz yaw inertia slug ft2 4100000 McCormick pg 624
Ixz I_xz lateral cross inertia slug ft2 0 assumed

Propulsion Data
Variable Variable
in Code 		Description Units Value(s) Source Notes
Tmax simpleSingleMaxThrust maximum thrust lb 60000 David pg 274 engine rating (990A)

Aerodynamic Data
Variable Variable
in Code 		Description Units Value(s) Source Notes
CD0 CDo drag coefficient at =0 - 0.024 Nelson pg ?
CD CD_a drag curve slope 1/rad 0.15 McCormick pg 624
CDe CD_de drag due to elevator 1/rad 0 assumed

e positive down

CL0 CLo lift coefficient at =0 - 0.347 Nelson pg ?
CL CL_a lift curve slope 1/rad 4.8 McCormick pg 624
CL CL_adot lift due to angle of attack rate 1/rad 2.7 McCormick pg 624
CLq CL_q lift due to pitch rate 1/rad 7.5 McCormick pg 624
CLe CL_de lift due to elevator 1/rad 0.19 McCormick pg 624 e positive down
Cm0 Cmo pitch moment coefficient at =0 - 0 Nelson pg ?
Cm Cm_a pitch moment due to angle of attack 1/rad -0.65 McCormick pg 624
Cm Cm_adot pitch moment due to angle of attack rate 1/rad -4.5 McCormick pg 624
Cmq Cm_q pitch moment due to pitch rate 1/rad -12 McCormick pg 624
Cme Cm_de pitching moment due to elevator 1/rad -0.57 McCormick pg 624 e positive down
CY CY_beta side force fue to sideslip angle 1/rad -0.812 Nelson pg ?
CYp CY_p side force due to roll rate 1/rad 0 Nelson pg ?
CYr CY_r side force due to yaw rate 1/rad 0.184 Nelson pg ?
CYa CY_da side force due to aileron 1/rad 0 assumed

a positive
right aileron up

CYr CY_dr side force due to rudder 1/rad 0.019 Nelson pg ? r positive left
Cl Cl_beta dihedral effect 1/rad -0.117 Nelson pg ?
Clp Cl_p roll damping 1/rad -0.312 Nelson pg ?
Clr Cl_r roll moment due to yaw rate 1/rad 0.153 Nelson pg ?
Cla Cl_da roll moment due to aileron 1/rad -0.05 Nelson pg ? a positive
right aileron up
Clr Cl_dr roll moment due to rudder 1/rad 0.019 Nelson pg ? r positive left
Cn Cn_beta weathercock stability 1/rad 0.129 Nelson pg ?
Cnp Cn_p adverse yaw 1/rad -0.011 Nelson pg ?
Cnr Cn_r yaw damping 1/rad -0.165 Nelson pg ?
Cna Cn_da yaw moment due to aileron 1/rad 0.008 Nelson pg ? a positive
right aileron up
Cnr Cn_dr yaw moment due to rudder 1/rad -0.076 Nelson pg ? r positive left

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