Flutter velocity performed for the ASROC missile determined using the FinSim Ug method. Table-1 presents a comparison between various flutter velocity methods and the Ug method used by FinSim. Table-2 displays FinSim input data derived from ASROC fin dimensional information presented in Figure-4. Figure-1, Figure-2 and Figure-3 display FinSim flutter velocity results using fin dimensional data presented in Table-2. Please see NACA RM SL58H08a, Test 38 for detailed information about the windtunnel method used to determine ASROC fin flutter.
 

UF METHOD, TABLE-2	FLUTTER VELOCITY (UF)	DIFFERENCE
FinSim_Ug	Mach 1.20	-7.7 %
FinSim main screen analysis	Mach 1.33	+ 2.3 %
NACA TN 4197 equation	Mach 1.319	+1.5 %
NACA RM SL58H08a (windtunnel)	Mach 1.3	NA
Table-1, Flutter velocity computation methods compared to the FinSim Ug method

 

FINSIM INPUT DESCRIPTIONS	VALUES	NOTES
Semi span (b)	3.42 in	Fin input geometry screen
Root chord (cr)	8.91 in	Fin input geometry screen
Tip chord (ct)	6.44 in	Fin input geometry screen
Sweep length	4.22 in	Fin input geometry screen
Fin thickness (t)	0.05 in	Fin input geometry screen
Maximum body diameter near fins	4.0 in	Fin input geometry screen
Fin Materials		Aluminum, main screen pull down
Shear modulus (G)	3759398 psi	Fin material, aluminum
Elastic modulus (E)	10E6 psi	Fin material, aluminum
Poissons ratio	0.33	Fin material, aluminum
Material density	0.098 lb/in3	Fin material, aluminum
Rocket simulation altitude (P) @ max Mach	29,000 ft	Pressure, main screen pull down
Supersonic Airfoil Lift Slope		Main screen pull down menu
Aerodynamic center location (A.C.)	0.50	0.5 for supersonic, main screen
CN-alpha method, NACA TN 4197		Supersonic lift slope method used
Aeroelastic input variables		E.A. and C.G. main screen inputs
Elastic axis location (E.A.)	0.50	Attachment centroid, main screen
Center of gravity location (C.G.)	0.694	Measured or computed, main screen
FinSim Results
FinSim main screen flutter analysis	Mach 1.33	See Figure-1
U-g Torsion-Flexure flutter velocity	Mach 1.2	See Figure-3
Table-2, FinSim input variables for performing supersonic flutter velocity analysis