Last updated June 7, 2000
The linear aerodynamics model uses stability derivatives to approximate actual aircraft behavior. The T-37A Tweet linear model is based on the following flight conditions (cruise):
|  | ||||||
| Variable | Variable in Code | Description | Units | Value(s) | Source | Notes | 
|---|---|---|---|---|---|---|
| h | Altitude | altitude above sea level | ft | 30000 | Roskam pg 501 |   | Alpha | angle of attack | deg | 2 | Roskam pg 501 | 
| V   | V_true_kts | velocity (true air speed) | kts | 270 | Roskam pg 501 | Mach 0.459 | 
| q | Dynamic_pressure | dynamic pressure | lb/ft2 | 92.7 | Roskam pg 501 | |
| C.G. | - | center of gravity location | %   | 27 | Roskam pg 501 | |
| 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:
|  | ||||||
| Variable | Variable in Code | Description | Units | Value(s) | Source | Notes | 
|---|---|---|---|---|---|---|
| b | bw | wingspan | ft | 33.8 | Roskam pg 501 | |
|   | cbar | wing mean aerodynamic chord | ft | 5.47 | Roskam pg 501 | |
| S | Sw | wing surface area | ft2 | 182 | Roskam pg 501 | |
|  | ||||||
| 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 | 
|  | ||||||
| Variable | Variable in Code | Description | Units | Value(s) | Source | Notes | 
|---|---|---|---|---|---|---|
| W | Weight | weight at flight condition | lb | 6360 | Roskam pg 501 | converted to Mass [slug/ft3] in code | 
| Ixx | I_xx | roll inertia | slug ft2 | 7985 | Roskam pg 501 | |
| Iyy | I_yy | pitch inertia | slug ft2 | 3326 | Roskam pg 501 | |
| Izz | I_zz | yaw inertia | slug ft2 | 11183 | Roskam pg 501 | |
| Ixz | I_xz | lateral cross inertia | slug ft2 | 0 | Roskam pg 501 | |
|  | ||||||
| Variable | Variable in Code | Description | Units | Value(s) | Source | Notes | 
|---|---|---|---|---|---|---|
| Tmax | simpleSingleMaxThrust | maximum thrust | lb | 850 | Roskam pg 502 | estimated from CTx at sea level | 
| Tmax | simpleSingleMaxThrust | maximum thrust | lb | 5700 | David pg 251 | engine rating (A-37B Dragonfly) | 
|  | ||||||
| Variable | Variable in Code | Description | Units | Value(s) | Source | Notes | 
|---|---|---|---|---|---|---|
| CD0 | CDo | drag coefficient at  =0 | - | 0.020 | Roskam pg 502 | |
| CD   | CD_a | drag curve slope | 1/rad | 0.25 | Roskam pg 502 | |
| CD  e | CD_de | drag due to elevator | 1/rad | 0 | Roskam pg 502 |  e positive down | 
| CL0 | CLo | lift coefficient at  =0 | - | 0.20 | Roskam pg 502 | |
| CL   | CL_a | lift curve slope | 1/rad | 5.15 | Roskam pg 502 | |
| CL   | CL_adot | lift due to angle of attack rate | 1/rad | 2.0 | Roskam pg 502 | |
| CLq | CL_q | lift due to pitch rate | 1/rad | 4.1 | Roskam pg 502 | |
| CL  e | CL_de | lift due to elevator | 1/rad | 0.5 | Roskam pg 502 |  e positive down | 
| Cm0 | Cmo | pitch moment coefficient at  =0 | - | 0.025 | Roskam pg 502 | |
| Cm   | Cm_a | pitch moment due to angle of attack | 1/rad | -0.70 | Roskam pg 502 | |
| Cm   | Cm_adot | pitch moment due to angle of attack rate | 1/rad | -6.95 | Roskam pg 502 | |
| Cmq | Cm_q | pitch moment due to pitch rate | 1/rad | -14.9 | Roskam pg 502 | |
| Cm  e | Cm_de | pitching moment due to elevator | 1/rad | -1.12 | Roskam pg 502 |  e positive down | 
| CY   | CY_beta | side force fue to sideslip angle | 1/rad | -0.346 | Roskam pg 503 | |
| CYp | CY_p | side force due to roll rate | 1/rad | -0.0827 | Roskam pg 503 | |
| CYr | CY_r | side force due to yaw rate | 1/rad | 0.30 | Roskam pg 503 | |
| CY  a | CY_da | side force due to aileron | 1/rad | 0 | Roskam pg 503 |  a positive right aileron up | 
| CY  r | CY_dr | side force due to rudder | 1/rad | 0.2 | Roskam pg 503 |  r positive left | 
| Cl   | Cl_beta | dihedral effect | 1/rad | -0.0944 | Roskam pg 503 | |
| Clp | Cl_p | roll damping | 1/rad | -0.442 | Roskam pg 503 | |
| Clr | Cl_r | roll moment due to yaw rate | 1/rad | 0.0926 | Roskam pg 503 | |
| Cl  a | Cl_da | roll moment due to aileron | 1/rad | -0.181 | Roskam pg 503 |  a positive right aileron up | 
| Cl  r | Cl_dr | roll moment due to rudder | 1/rad | 0.015 | Roskam pg 503 |  r positive left | 
| Cn   | Cn_beta | weathercock stability | 1/rad | 0.1106 | Roskam pg 503 | |
| Cnp | Cn_p | adverse yaw | 1/rad | -0.0243 | Roskam pg 503 | |
| Cnr | Cn_r | yaw damping | 1/rad | -0.139 | Roskam pg 503 | |
| Cn  a | Cn_da | yaw moment due to aileron | 1/rad | 0.0254 | Roskam pg 503 |  a positive right aileron up | 
| Cn  r | Cn_dr | yaw moment due to rudder | 1/rad | -0.0365 | Roskam pg 503 |  r positive left |