1 Critical Design Review Ashley Brawner Neelam Datta Xing Huang Jesse Jones Team 2: Balsa to the Wall and the TFM-2 Matt Negilski Mike Palumbo Chris Selby Tara Trafton

2 of 48 Presentation Overview Aerodynamics Propulsion Structures D&C Specifications Summary

3 of 48 Aerodynamics Overview Airfoil Selection Taper Ratio Aspect Ratio Drag Model  Parasite, Induced, Viscous Max C L & Flaps Aero Design Summary

4 of 48 Airfoil Selection: Main Wing Wing Section  Design Requirements Gives approximate 2D C l needed for dash Relatively thin for minimizing drag Thick enough for structural considerations  Other Considerations Availability of empirical data  Conclusion: NACA 1408

5 of 48 Airfoil Selection: Tail Tail Sections  Horizontal Stabilizer Symmetric with low C d over a wider range of α (0 - 5 degrees)  Conclusion : Jones airfoil (8% t/c)  Vertical Stabilizer Symmetric with low C d at low α (0 degrees)  Conclusion : NACA 0006

6 of 48 Taper Ratio Ideal lift distribution is elliptical (minimizes induced drag) λ=0.45 gives closest elliptical lift distribution Less than 1% higher induced drag than ideal (Raymer) Figure from Raymer textbook

7 of 48 AR Trade Study High C L  Drag-due-to-lift dominates High AR Low C L  Parasite drag dominates Low AR C L design ≈  AR needs to be small

8 of 48 Drag Build-up Method C f c = Component skin friction coefficient FF c = Component form factor Q c = Component interference effects S wet,c = Component wetted area S ref = Wing planform Method from Raymer textbook

9 of 48 Component Friction Coefficient Figure from Nicolai paper

10 of 48 Aircraft Drag Polar Takes into account having a cambered wing.  Minimum drag occurs at some non-zero C L Models inviscid and viscous drag-due-to-lift.  K′ is the inviscid drag-due-to-lift factor Due to trailing edge vortices (induced drag)  K′′ is the viscous drag-due-to-lift factor Due to transition and increased skin friction Method from Nicolai paper

11 of 48 Aircraft Drag Polar (cont.) More involved (next slide) Method from Nicolai paper Assumes that the zero lift angle of attack is the same for 2D and 3D

12 of 48 Aircraft Drag Polar (cont.) Method from Nicolai paper

13 of 48 Effect of Flaps Figure from Nicolai textbook

14 of 48 Aerodynamics Summary

15 of 48 Propulsion Overview Ducted Fan Basics Propulsion System Thrust Model Duct Design

16 of 48 Ducted Fan Applications Wind Tunnels Hovercraft Tail Rotor Similar to: High Bypass Turbofan

17 of 48 Ducted Fan Basics Pros  No Propeller Tip Downwash  Direct Drive  High Static Thrust  No Landing Gear Hand Launch / Belly Landing No Landing Gear Drag Cons  Duct Profile Drag  High RPM  Duct Weight  High Amperage  Dangerous Belly Landing

18 of 48 Propulsion System WeMoTec Midi Fan  Fan Dia: 3.5 in  Max RPM: 35,000  Weight: 0.25 lbf

19 of 48 Propulsion System Cont’d Electrifly Ammo  Kv: 2300 RPM/Volt  Max Cont. Current: 60 Amps  Max Surge* Current: 100 Amps  Max Cont. Power: 1.5 hp A123 Systems M1 Li-Ion Cells  5 cells in Series  Capacity: 2300 mAh  Voltage: 18 Volts  Max Cont. Current: 70 Amps  Max Surge* Current: 120 Amps * - Surge is 10 sec

20 of 48 Thrust Model Cont’d Thrust at Max RPM (35,000 RPM) Thrust at Operating RPM (30,000 RPM) Stall Speed = 30 ft/s Thrust Required Max Speed 107 ft/s ( 72 mph )

21 of 48 Duct Design FSA highlighted in blue D Fan = Diameter of Fan D Hub = Diameter of Hub Duct Inlet  129 % of Fan Swept Area (FSA) Converging Nozzle Ensure Sufficient Mass Flow Ingest Boundary Layer Duct Exit  85 % of FSA Converging Nozzle Raise Exhaust Velocity Optimized for High Speed

22 of 48 Duct Design Cont’d Duct Intake Area  9.81 in 2 Duct Intake Diameter  3.53 in Duct Intake Length  3.57 in Duct Exit Area  6.85 in 2 Duct Exit Diameter  2.95 in Duct Exit Length  3 in

23 of 48 Duct Integration

24 of 48 Propulsion Summary

25 of 48 Structures Overview V-n Diagram Analysis of Wing Loads Wing/Boom Structure Fuselage and Tail CATIA Model

26 of 48 Preliminary Weight Estimate

27 of 48 V-n Diagram Maximum Design Load Factor = 7.5

28 of 48 Structural Properties of Wing Discretized wing into ten sections Initially, elliptic airfoil approximation Bending and polar moments of inertia found at each station using XFOIL Foam core, fiberglass skin construction Foam neglected in analysis

29 of 48 Bending Analysis M = bending moment y = vertical distance from neutral axis I(t) = moment of inertia, a function of skin thickness, t

30 of 48 Twisting Analysis T = Torque Cm = Moment coefficient c = Chord length phi = Twist angle/unit length

31 of 48 Wing Structure [0/90] Woven Cloth E_1 [Msi]3.5 E_2 [Msi]3.5 G_12 [Msi] Ply Laminate[0/45] E_x [Msi]2.87 E_y [Msi]2.87 G_xy [Msi]1.13 Skin: 2 oz E-glass Cloth EZ-Lam Epoxy Core: Expanded Polystyrene Foam 3 Ply Laminate[-45/0/45] E_x [Msi]2.62 E_y [Msi]2.62 G_xy [Msi]1.28

32 of 48 Wing Structure Shaped balsa blocks integrated into wing foam at boom, fuselage, and motor/duct mount interfaces Carbon fiber composite arrow shafts for booms Fiberglass over wing/boom structure

33 of 48 Fuselage and Tail Fuselage  Foam core on CNC due to advanced geometry  3 oz satin weave fiberglass and epoxy Horizontal and vertical tails  Hot wire cut foam cores  2 oz plain weave fiberglass and epoxy

34 of 48 Component Integration

35 of 48 CATIA Model Contribution Visualization of design Wetted areas Aircraft weight Accurate CG calculation/placement Moments and products of inertia Manufacturing necessity

36 of 48 Structures Summary Dual boom design contributes significantly to structural design of wing Twist is dominant constraint Foam core/fiberglass skin construction Value of CATIA model

37 of 48 D&C Overview Tail Sizing Control surface sizing Trim diagram Yaw rate feedback control system

38 of 48 Horizontal Tail Longitudinal X-plot Tail area = 90 in 2  Chord = 5 in  Span = 18 in  AR = 3.6 Static margin 18 %

39 of 48 Vertical Tail – Twin Tail Config. Directional X-plot Tail area = 30 in 2  Chord = 5 in  Span = 6 in  AR = 1.2 Weathercock stability = rad -1 Total vertical tail area 60 in 2

40 of 48 Control Surface Sizing Elevator  25% of chord = 1.25 inches  Elevator effectiveness (C mδe ) = rad -1 Rudder – Only one rudder on twin-tail  50% of chord = 2 inches  Rudder effectiveness (C nδr ) = rad -1

41 of 48 Trim Diagram Limitations  Tail Stall at α = 7.2 º  C L,max = 1.06 Trim Velocity  92 ft/sec From Trim Diagram  δ e range -1 º -8 º C L max CLCL C m 0.25c α = 3 o α = 7 o α = -1 o C m = 0 X cg forward C m = 0 X cg nominal C m = 0 X cg aft

42 of 48 Feedback Control System Dutch roll mode damping ratio required to be at least 0.8 Without feedback control system damping ratio is Integration of feedback controller with control law gain of increases dutch roll mode damping ratio to 0.81

43 of 48 Feedback Control System Futaba Servo Control Law and Rate Gyro Gains Yaw Rate Aircraft Transfer Function δr [rad] Yaw rate [r/s]

44 of 48 D&C Summary Horizontal tail area 90 in 2 for static margin of 18% Vertical tail area 60 in 2 for weathercock stability Feedback control system with control law gain of needed to meet dutch roll mode damping of 0.8

45 of 48 CATIA Model 3-View

46 of 48 Summary

47 of 48 Questions?

48 of 48 Appendix

49 of 48 Aerodynamics Appendix

50 of 48 Airfoil Selection: Main Wing (cont.)

51 of 48 Airfoil Selection: Tail (cont.)

52 of 48 XFOIL α stall vs. actual α stall

53 of 48 XFOIL α stall vs. actual α stall (cont.)

54 of 48 XFOIL α stall vs. actual α stall (cont.)

55 of 48 Finding

56 of 48 Propulsion Appendix

57 of 48 Thrust Calculations

58 of 48 Structures Appendix

59 of 48 Wing Skin Material With 4 oz E-glass/Epoxy Wing Area [in^2] Wing Area [yd^2]1.130 Fiberglass Weight [lbf]0.283 Epoxy Weight [lbf]0.283 Wing Volume [in^3] Wing Volume [ft^3]0.277 Foam Weight [lbf]0.485 Wing Weight [lbf]1.050 Φ = deg Deflection = 2e-6 in

60 of 48 Wing Skin Material builders/finishing_techniques/apply_fiberglass_finish/index.htm

61 of 48 Material Properties Material Properties Table E-Glass Fiber S-Glass Fiber E-glass (Fabric) Balsa Wood Carbon Fiber Polyurethane Foam Density (lbs/in^3) Tensile Strength (ksi) Shear Strength (ksi) Longitudinal Young's Modulus (10^6 psi) Transverse Young's Modulus (10^6 psi) Shear Modulus (10^6 psi) Poisson's Ratio

62 of 48 V-n Diagram Design Point:  Vertical turn radius = 28 ft  Velocity = 60 ft/s  Load factor = 5

63 of 48 Load Factor – Max Lift

64 of 48 Load Factor – Level Turn

65 of 48 Load Factor – Vertical Turn

66 of 48 Wing Centroid

67 of 48 Comparison I_xx_area_ avg_error22.70% I_xx_skin_ avg_error6.79% J_area_ avg_error23.81% J_skin_ avg_error27.30% Airfoil Tip Deflection [ft] 1.386E-04 Ellipse Tip Deflection [ft] 1.298E-04 Airfoil Tip Twist [deg] Ellipse Tip Twist [deg]

68 of 48 D&C Appendix

69 of 48 D&C Appendix Horizontal tail sizing method LongitudinalX-plot Set center of gravity location at the quarter-chord Plot aerodynamic center of aircraft as a function of the horizontal tail area

70 of 48 D&C Appendix Vertical tail sizing method directional X-plot Use of twin-tail configuration to determine weathercock stability as a function of vertical tail area All equations result in rad -1

71 of 48 D&C Appendix Open loop poles of aircraft yaw rate transfer function Eigenvalue Damping Freq. (rad/s) 0.00e e e e e e e e+000i 2.12e e e e+000i 2.12e e e e e+000

72 of 48 Appendix: Control System Root Locus Use of SISOTool to help determine the correct gain to use

73 of 48 Appendix Control system closed loop poles: Eigenvalue Damping Freq. (rad/s) 0.00e e e e e e e e+000i 8.40e e e e+000i 8.40e e e e e e e+001i 6.32e e e e+001i 6.32e e+001