Convair 880 -- Linear Model
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):
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| 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:
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| Variable |
Variable in Code |
Description | Units | Value(s) | Source | Notes |
|---|---|---|---|---|---|---|
| b | bw | wingspan | ft | 120 | Nelson pg 414 | |
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cbar | wing mean aerodynamic chord | ft | 18.94 | Nelson pg 414 | |
| S | Sw | wing surface area | ft2 | 2000 | Nelson pg 414 | |
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| Variable |
Variable in Code |
Description | Units | Value(s) | Source | Notes |
|---|---|---|---|---|---|---|
 emax
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demax | maximum elevator deflection | deg | +20 | - | guess |
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emin
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demin | minimum elevator deflection | deg | -20 | - | guess |
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amax
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damax | maximum aileron deflection | deg | +20 | - | guess |
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amin
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damin | minimum aileron deflection | deg | -20 | - | guess |
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rmax
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drmax | maximum rudder deflection | deg | +20 | - | guess |
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rmin
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drmin | minimum rudder deflection | deg | -20 | - | guess |
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| 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 | |
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| Variable |
Variable in Code |
Description | Units | Value(s) | Source | Notes |
|---|---|---|---|---|---|---|
| Tmax | simpleSingleMaxThrust | maximum thrust | lb | 60000 | David pg 274 | engine rating (990A) |
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| 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 | |
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CDe
|
CD_de | drag due to elevator | 1/rad | 0 |
assumed
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| 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 | |
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CLe
|
CL_de | lift due to elevator | 1/rad | 0.19 | McCormick pg 624 |
e positive down
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| Cm0 | Cmo |
pitch moment coefficient at =0
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- | 0 | Nelson pg ? | |
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Cm
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Cm_a | pitch moment due to angle of attack | 1/rad | -0.65 | McCormick pg 624 | |
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Cm
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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 | |
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Cme
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Cm_de | pitching moment due to elevator | 1/rad | -0.57 | McCormick pg 624 |
e positive down
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CY
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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 ? | |
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CYa
|
CY_da | side force due to aileron | 1/rad | 0 |
assumed
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CYr
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CY_dr | side force due to rudder | 1/rad | 0.019 | Nelson pg ? |
r positive left
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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 ? | |
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Cla
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Cl_da | roll moment due to aileron | 1/rad | -0.05 | Nelson pg ? |
a positive right aileron up |
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Clr
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Cl_dr | roll moment due to rudder | 1/rad | 0.019 | Nelson pg ? |
r positive left
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Cn
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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 ? | |
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Cna
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Cn_da | yaw moment due to aileron | 1/rad | 0.008 | Nelson pg ? |
a positive right aileron up |
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Cnr
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Cn_dr | yaw moment due to rudder | 1/rad | -0.076 | Nelson pg ? |
r positive left
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