F-104 Starfighter -- 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 2, 2000

The linear aerodynamics model uses stability derivatives to approximate actual aircraft behavior. The F-104 linear model is based on the following flight conditions (cruise):

Variable	Variable in Code	Description	Units	Value(s)	Source	Notes
Flight Conditions
h	Altitude	altitude above sea level	ft	55000	Roskam pg 529
	Alpha	angle of attack	deg	2	Roskam pg 529
V	V_true_kts	velocity (true air speed)	kts	1031.4	Roskam pg 529	Mach 1.8
q	Dynamic_pressure	dynamic pressure	lb/ft²	434.5	Roskam pg 529
C.G.	-	center of gravity location	%	7	Roskam pg 529
C_L	CL	lift coefficient	-	?		not available
C_D	CD	drag coefficient	-	?		not available
C_m	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
Geometry
b	bw	wingspan	ft	21.9	Roskam pg 529
	cbar	wing mean aerodynamic chord	ft	9.6	Roskam pg 529
S	Sw	wing surface area	ft²	196	Roskam pg 529

Control Surface Geometry

Variable Variable
in Code Description Units Value(s) Source Notes

e_max demax maximum elevator deflection deg +20 - guess

e_min demin minimum elevator deflection deg -20 - guess

a_max damax maximum aileron deflection deg +20 - guess

a_min damin minimum aileron deflection deg -20 - guess

r_max drmax maximum rudder deflection deg +20 - guess

r_min drmin minimum rudder deflection deg -20 - guess

Control Surface Geometry
Variable	Variable in Code	Description	Units	Value(s)	Source	Notes
e_max	demax	maximum elevator deflection	deg	+20	-	guess
e_min	demin	minimum elevator deflection	deg	-20	-	guess
a_max	damax	maximum aileron deflection	deg	+20	-	guess
a_min	damin	minimum aileron deflection	deg	-20	-	guess
r_max	drmax	maximum rudder deflection	deg	+20	-	guess
r_min	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 16300 Roskam pg 529 converted to Mass
[slug/ft³] in code

I_xx I_xx roll inertia slug ft² 3600 Roskam pg 529

I_yy I_yy pitch inertia slug ft² 59000 Roskam pg 529

I_zz I_zz yaw inertia slug ft² 60000 Roskam pg 529

I_xz I_xz lateral cross inertia slug ft² 0 Roskam pg 529

Mass Data
Variable	Variable in Code	Description	Units	Value(s)	Source	Notes
W	Weight	weight at flight condition	lb	16300	Roskam pg 529	converted to Mass [slug/ft³] in code
I_xx	I_xx	roll inertia	slug ft²	3600	Roskam pg 529
I_yy	I_yy	pitch inertia	slug ft²	59000	Roskam pg 529
I_zz	I_zz	yaw inertia	slug ft²	60000	Roskam pg 529
I_xz	I_xz	lateral cross inertia	slug ft²	0	Roskam pg 529

Propulsion Data

Variable Variable
in Code Description Units Value(s) Source Notes

T_max simpleSingleMaxThrust maximum thrust lb 5050 Roskam pg 530 estimated from C_{T_x}
at sea level

T_max simpleSingleMaxThrust maximum thrust lb 7800 MAM site engine rating
(F-104A)

T_max simpleSingleMaxThrust maximum thrust lb 15800 MAM site engine rating
(F-104G)

T_max simpleSingleMaxThrust maximum thrust lb 18800 MAM site engine rating
(F-104S)

Propulsion Data
Variable	Variable in Code	Description	Units	Value(s)	Source	Notes
T_max	simpleSingleMaxThrust	maximum thrust	lb	5050	Roskam pg 530	estimated from C_{T_x} at sea level
T_max	simpleSingleMaxThrust	maximum thrust	lb	7800	MAM site	engine rating (F-104A)
T_max	simpleSingleMaxThrust	maximum thrust	lb	15800	MAM site	engine rating (F-104G)
T_max	simpleSingleMaxThrust	maximum thrust	lb	18800	MAM site	engine rating (F-104S)

Aerodynamic Data

Variable Variable
in Code Description Units Value(s) Source Notes

C_D₀ CDo drag coefficient at =0 - 0.048 Roskam pg 530

C_D CD_a drag curve slope 1/rad 0.384 Roskam pg 530

C_{D_e} CD_de drag due to elevator 1/rad 0 Roskam pg 530 e positive down

C_L₀ CLo lift coefficient at =0 - 0.122 Roskam pg 530

C_L CL_a lift curve slope 1/rad 2.005 Roskam pg 530

C_L CL_adot lift due to angle of attack rate 1/rad 0.82 Roskam pg 530

C_{L_q} CL_q lift due to pitch rate 1/rad 1.9 Roskam pg 530

C_{L_e} CL_de lift due to elevator 1/rad 0.523 Roskam pg 530 e positive down

C_m₀ Cmo pitch moment coefficient at =0 - -0.028 Roskam pg 530

C_m Cm_a pitch moment due to angle of attack 1/rad -1.308 Roskam pg 530

C_m Cm_adot pitch moment due to angle of attack rate 1/rad -2.05 Roskam pg 530

C_{m_q} Cm_q pitch moment due to pitch rate 1/rad -4.83 Roskam pg 530

C_{m_e} Cm_de pitching moment due to elevator 1/rad -1.31 Roskam pg 530 e positive down

C_Y CY_beta side force fue to sideslip angle 1/rad -1.045 Roskam pg 531

C_{Y_p} CY_p side force due to roll rate 1/rad 0 Roskam pg 531

C_{Y_r} CY_r side force due to yaw rate 1/rad 0 Roskam pg 531

C_{Y_a} CY_da side force due to aileron 1/rad 0 Roskam pg 531 a positive
right aileron up

C_{Y_r} CY_dr side force due to rudder 1/rad 0.87 Roskam pg 531 r positive left

C_l Cl_beta dihedral effect 1/rad -0.093 Roskam pg 531

C_{l_p} Cl_p roll damping 1/rad -0.272 Roskam pg 531

C_{l_r} Cl_r roll moment due to yaw rate 1/rad 0.154 Roskam pg 531

C_{l_a} Cl_da roll moment due to aileron 1/rad -0.0173 Roskam pg 531 a positive
right aileron up

C_{l_r} Cl_dr roll moment due to rudder 1/rad 0.0079 Roskam pg 531 r positive left

C_n Cn_beta weathercock stability 1/rad 0.242 Roskam pg 531

C_{n_p} Cn_p adverse yaw 1/rad -0.093 Roskam pg 531

C_{n_r} Cn_r yaw damping 1/rad -0.649 Roskam pg 531

C_{n_a} Cn_da yaw moment due to aileron 1/rad -0.0025 Roskam pg 531 a positive
right aileron up

C_{n_r} Cn_dr yaw moment due to rudder 1/rad -0.0435 Roskam pg 531 r positive left

Variable	Variable in Code	Description	Units	Value(s)	Source	Notes
Aerodynamic Data
C_D₀	CDo	drag coefficient at =0	-	0.048	Roskam pg 530
C_D	CD_a	drag curve slope	1/rad	0.384	Roskam pg 530
C_{D_e}	CD_de	drag due to elevator	1/rad	0	Roskam pg 530	e positive down
C_L₀	CLo	lift coefficient at =0	-	0.122	Roskam pg 530
C_L	CL_a	lift curve slope	1/rad	2.005	Roskam pg 530
C_L	CL_adot	lift due to angle of attack rate	1/rad	0.82	Roskam pg 530
C_{L_q}	CL_q	lift due to pitch rate	1/rad	1.9	Roskam pg 530
C_{L_e}	CL_de	lift due to elevator	1/rad	0.523	Roskam pg 530	e positive down
C_m₀	Cmo	pitch moment coefficient at =0	-	-0.028	Roskam pg 530
C_m	Cm_a	pitch moment due to angle of attack	1/rad	-1.308	Roskam pg 530
C_m	Cm_adot	pitch moment due to angle of attack rate	1/rad	-2.05	Roskam pg 530
C_{m_q}	Cm_q	pitch moment due to pitch rate	1/rad	-4.83	Roskam pg 530
C_{m_e}	Cm_de	pitching moment due to elevator	1/rad	-1.31	Roskam pg 530	e positive down
C_Y	CY_beta	side force fue to sideslip angle	1/rad	-1.045	Roskam pg 531
C_{Y_p}	CY_p	side force due to roll rate	1/rad	0	Roskam pg 531
C_{Y_r}	CY_r	side force due to yaw rate	1/rad	0	Roskam pg 531
C_{Y_a}	CY_da	side force due to aileron	1/rad	0	Roskam pg 531	a positive right aileron up
C_{Y_r}	CY_dr	side force due to rudder	1/rad	0.87	Roskam pg 531	r positive left
C_l	Cl_beta	dihedral effect	1/rad	-0.093	Roskam pg 531
C_{l_p}	Cl_p	roll damping	1/rad	-0.272	Roskam pg 531
C_{l_r}	Cl_r	roll moment due to yaw rate	1/rad	0.154	Roskam pg 531
C_{l_a}	Cl_da	roll moment due to aileron	1/rad	-0.0173	Roskam pg 531	a positive right aileron up
C_{l_r}	Cl_dr	roll moment due to rudder	1/rad	0.0079	Roskam pg 531	r positive left
C_n	Cn_beta	weathercock stability	1/rad	0.242	Roskam pg 531
C_{n_p}	Cn_p	adverse yaw	1/rad	-0.093	Roskam pg 531
C_{n_r}	Cn_r	yaw damping	1/rad	-0.649	Roskam pg 531
C_{n_a}	Cn_da	yaw moment due to aileron	1/rad	-0.0025	Roskam pg 531	a positive right aileron up
C_{n_r}	Cn_dr	yaw moment due to rudder	1/rad	-0.0435	Roskam pg 531	r positive left

F-104 Starfighter -- Linear Model

Flight Sim Home * Aircraft Models * F-104 Model * F-104 References

**Flight Sim Home * Aircraft Models * F-104 Model * F-104 References**