1

Critical Design ReviewCritical 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 OverviewPresentation Overview

Aerodynamics Propulsion Structures D&C Specifications

Summary

3 of 48

Aerodynamics OverviewAerodynamics Overview

Airfoil Selection Taper Ratio Aspect Ratio Drag Model

Parasite, Induced, Viscous Max CL & Flaps Aero Design Summary

4 of 48

Airfoil Selection: Airfoil Selection: Main WingMain Wing

Wing Section Design Requirements

Gives approximate 2D Cl 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: Airfoil Selection: TailTail

Tail Sections Horizontal Stabilizer

Symmetric with low Cd over a wider range of α (0 - 5 degrees)

Conclusion : Jones airfoil (8% t/c)

Vertical Stabilizer Symmetric with low Cd at low α (0 degrees)

Conclusion : NACA 0006

6 of 48

Taper RatioTaper 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 StudyAR Trade StudyLines of constant C

D (An AR trade study)

AR

CL

0.02550.026 0.0265

0.027 0.0275 0.0280.029

0.03

0.035

0.04

0.05

0.06

0.08

0.10.12

3 4 5 6 7 8 9 10 11 120

0.2

0.4

0.6

0.8

1

1.2

High CL

Drag-due-to-lift dominates High AR

Low CL

Parasite drag dominates Low AR

CL design ≈ 0.083 AR needs to be

small

8 of 48

Drag Build-up MethodDrag Build-up Method Cfc = Component skin

friction coefficient FFc = Component form

factor Qc = Component

interference effects Swet,c = Component

wetted area Sref = Wing planform

ref

c cwetccfD S

SQFFCC c ,

0

Method from Raymer textbook

9 of 48

Component Friction CoefficientComponent Friction Coefficient

Figure from Nicolai paper

10 of 48

Aircraft Drag PolarAircraft Drag Polar

2

min0 LLDD CCKKCC

Takes into account having a cambered wing. Minimum drag occurs at some non-zero CL

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.)Aircraft Drag Polar (cont.)

2

min0 LLDD CCKKCC

eARK

1

minmin lL CC 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.)Aircraft Drag Polar (cont.)

2

min0 LLDD CCKKCC

Method from Nicolai paper

Viscous Drag Coefficient K′′ for NACA 1408

Overall:y = 0.0243x + 0.0045

High Speed Region:y = 0.0167x + 0.0051

0

0.005

0.01

0.015

0.02

0.025

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

(Cl-Clmin)2

Cd Overall

High Speed

K′′ = 0.0167

13 of 48

Effect of Flaps Effect of Flaps

maxmaxmax LLL CCCclean

KS

SCC

W

WFlL maxmax

92.0coscos08.01 4/4/3

4/2 ccK

cleanclean lL CCmaxmax

9.0

S

SCCC WFllL

clean maxmaxmax92.09.0

Figure from Nicolai textbook

14 of 48

Aerodynamics SummaryAerodynamics Summary

Main Airfoil NACA 1408 CL,o 0.152

Horz. Tail Jones (8%) CL,α (1/rad) 4.3719

Vert. Tail NACA 0006 CL,max (clean) 0.85

S (ft2) 4.95 CL,max (flapped) 1.06

AR 5 CD,min 0.018

Taper 0.45 Cf ,e 0.00587

MGC (ft) 1

% Chord 20Max δf (deg) 35

∆CL 0.21

SWF (ft2) 1.75

Flaps Design

Wing Design Aircraft

15 of 48

Propulsion OverviewPropulsion Overview

Ducted Fan Basics Propulsion System Thrust Model Duct Design

16 of 48

Ducted Fan ApplicationsDucted Fan Applications

Wind Tunnels

Hovercraft

Tail Rotor

Similar to:High Bypass Turbofan

17 of 48

Ducted Fan BasicsDucted 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

System Propeller Ducted Fan

Method Retractable Landing Gear Hand Launch

Weight 0.91 lbf 0.65 lbf

Cost $70.00 $60.00

Weight & Cost Comparison

18 of 48

Propulsion SystemPropulsion System

WeMoTec Midi Fan Fan Dia: 3.5 in Max RPM: 35,000 Weight: 0.25 lbf

19 of 48

Propulsion System Cont’dPropulsion System Cont’d Electrifly Ammo 36-50-2300

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’dThrust Model Cont’d

Thrust atMax RPM(35,000 RPM)

Thrust atOperating RPM(30,000 RPM)

Stall Speed = 30 ft/sThrust Required Max Speed

107 ft/s( 72 mph )

21 of 48

Duct DesignDuct Design

44

22HubFan DD

FSA

FSA highlighted in blueDFan = Diameter of FanDHub = 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’dDuct Design Cont’d Duct Intake Area

9.81 in2

Duct Intake Diameter 3.53 in

Duct Intake Length 3.57 in

Duct Exit Area 6.85 in2

Duct Exit Diameter 2.95 in

Duct Exit Length 3 in

23 of 48

Duct IntegrationDuct Integration

24 of 48

Propulsion SummaryPropulsion Summary

High Speed Max Endurance

RPM 30,000 RPM 15,000 RPMVoltage 16.1 Volts 7.4 VoltsAmps 73.7 Amps 19.9 VoltsPower 1.59 hp 0.21 hp

107 ft/ s 47 ft/ s( 65 mph ) ( 32 mph )

Speed

Propulsion Performance

Unit Manufacturer Model CostDucted Fan Wemotec Midi Fan $56.50

Motor Great Planes Ammo 36-50-2300 $79.99Batteries A123 5 X HS-DK-4 $55.00

Total $191.49

Propulsion Costs & Weights

25 of 48

Structures OverviewStructures Overview

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

26 of 48

Preliminary Weight EstimatePreliminary Weight Estimate

27 of 48

V-n DiagramV-n Diagram

2

2V

W

SCn L

dashdive VV 25.1

2

2V

W

SCn L

Maximum Design Load Factor = 7.5

28 of 48

Structural Properties of WingStructural 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 AnalysisBending Analysis

0 0.5 1 1.5 2 2.50

5

10

15

20

25Bending Moment vs. Span

Distance from Root [ft]

Ben

ding

Mom

ent

[ft-

lb]

tIyM

bending

M = bending moment

y = vertical distance from neutral axis

I(t) = moment of inertia, a function of skin thickness, t

30 of 48

Twisting AnalysisTwisting Analysis

cSCVT m2

2

1 GJ

TL

T = Torque

Cm = Moment coefficient

c = Chord length

phi = Twist angle/unit length0 0.5 1 1.5 2 2.5

-6

-5

-4

-3

-2

-1

0Torque vs. Distance from Root

Distance from Root [ft]

Tor

que

[ft-

lbf]

31 of 48

Wing StructureWing Structure

[0/90] Woven Cloth

E_1 [Msi] 3.5

E_2 [Msi] 3.5

G_12 [Msi] 0.68

2 Ply Laminate [0/45]

E_x [Msi] 2.87

E_y [Msi] 2.87

G_xy [Msi] 1.13

Skin: 2 oz E-glass ClothEZ-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 StructureWing 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 TailFuselage 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 IntegrationComponent Integration

35 of 48

CATIA Model ContributionCATIA Model Contribution

Visualization of design Wetted areas Aircraft weight Accurate CG calculation/placement Moments and products of inertia Manufacturing necessity

36 of 48

Structures SummaryStructures 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 OverviewD&C Overview

Tail Sizing Control surface sizing Trim diagram Yaw rate feedback control system

38 of 48

Horizontal TailHorizontal Tail

Longitudinal X-plot Tail area = 90 in2

Chord = 5 in Span = 18 in AR = 3.6

Static margin 18 %

39 of 48

Vertical Tail – Twin Tail Config.Vertical Tail – Twin Tail Config.

Directional X-plot Tail area = 30 in2

Chord = 5 in Span = 6 in AR = 1.2

Weathercock stability = 0.102 rad-1

Total vertical tail area 60 in2

40 of 48

Control Surface SizingControl Surface Sizing

Elevator 25% of chord = 1.25 inches Elevator effectiveness (Cmδe) = -1.28 rad-1

Rudder – Only one rudder on twin-tail 50% of chord = 2 inches Rudder effectiveness (Cnδr) = -0.031 rad-1

41 of 48

Trim DiagramTrim Diagram

Limitations Tail Stall at

α = 7.2º

CL,max = 1.06 Trim Velocity

92 ft/sec From Trim

Diagram δe range -1º-8º

-0.4-0.3-0.2-0.100.10.20.3-0.2

0

0.2

0.4

0.6

0.8

1

1.2

CLmax

CL

Cm0.25c

α = 3o

α = 7o

α = -1o

Cm = 0

Xcg forward

Cm = 0

Xcg nominal

Cm = 0

Xcg aft

42 of 48

Feedback Control SystemFeedback Control System

Dutch roll mode damping ratio required to be at least 0.8

Without feedback control system damping ratio is 0.212

Integration of feedback controller with control law gain of -0.45 increases dutch roll mode damping ratio to 0.81

43 of 48

Feedback Control SystemFeedback Control System

+

-

-0.45 1

95040

9502 ss

Futaba Servo

Control Law and Rate Gyro Gains

)587.8244.1)(2114.0)(461.5(

)4492.0)(7033.0)(821.5(7924.92

ssss

sssr

Yaw Rate Aircraft Transfer Function

δr [rad]Yaw rate

[r/s]

44 of 48

D&C SummaryD&C Summary

Horizontal tail area 90 in2 for static margin of 18%

Vertical tail area 60 in2 for weathercock stability

Feedback control system with control law gain of -0.45 needed to meet dutch roll mode damping of 0.8

45 of 48

CATIA Model 3-ViewCATIA Model 3-View

46 of 48

SummarySummary

Total length (in) 53.24Wing span (ft) 60Wing root chord (in) 16.47Wing tip chord (in) 7.42Tail span (in) 18Tail height (in) 6Weight (lbf) 5.5Stall speed (ft/sec) 30Top speed (ft/sec) 107

Design Specifications

47 of 48

Questions?Questions?

48 of 48

Appendix

49 of 48

Aerodynamics Appendix

50 of 48

Airfoil Selection: Airfoil Selection: Main Wing (cont.)Main Wing (cont.)

XFOIL: Drag Polar

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1.2

0 0.005 0.01 0.015 0.02 0.025 0.03

Cd

Cl Jones Airfoil

NACA 1408MH 30

MH 64

Design Cl = 0.15

51 of 48

Airfoil Selection: Airfoil Selection: Tail (cont.)Tail (cont.)Various Airfoil Cd-α curves

0.004

0.005

0.006

0.007

0.008

0.009

0.01

0.011

0.012

0.013

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

α [deg]

Cd

NACA 0006

NACA 0007

NACA 0008

Jones (6.8% t/c)

Jones (7.2% t/c)

Jones (8% t/c)

52 of 48

XFOIL XFOIL ααstall stall vs. actual vs. actual ααstall stall NACA 1408 Cl-α curve

Re = 3,000,000

-1

-0.5

0

0.5

1

1.5

2

-10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20

α [deg]

Cl

Experimental

Numerical

XFOILClCl maxmax 8.0

53 of 48

XFOIL XFOIL ααstall stall vs. actual vs. actual ααstall stall (cont.)(cont.) NACA 1408 Cl-α curve

Re = 6,000,000

-1

-0.5

0

0.5

1

1.5

2

-10 -5 0 5 10 15 20 25

α [deg]

Cl

Experimental

Numerical

XFOILClCl maxmax 8.0

54 of 48

XFOIL XFOIL ααstall stall vs. actual vs. actual ααstall stall (cont.)(cont.)NACA 1408 Cl-α curve

Re = 9,000,000

-1

-0.5

0

0.5

1

1.5

2

-10 -5 0 5 10 15 20 25

α [deg]

Cl

Experimental

Numerical

XFOILClCl maxmax 8.0

55 of 48

maxlCFinding Finding

NACA 1408 section with flaps (XFOIL @ Re=5.0e5)

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

-4 -2 0 2 4 6 8 10

α (deg)

Cl

Clean NACA 1408

Flap: x/c=0.8, 30 degrees

maxlC

56 of 48

Propulsion Appendix

57 of 48

Thrust CalculationsThrust Calculations

VVmVmT eA D2SCV

2

1 RT

DragofCoeffC

AreaWingS

AreaSweptFanA

DensityStreamFree

VelocityStreamFreeV

FanofVelocityExitV

FlowMassAVm

AvailableThrustT

D

e

e

A

.

58 of 48

Structures Appendix

59 of 48

Wing Skin MaterialWing Skin Material

With 4 oz E-glass/EpoxyWing Area [in^2] 1465.078

Wing Area [yd^2] 1.130

Fiberglass Weight [lbf] 0.283

Epoxy Weight [lbf] 0.283

   

Wing Volume [in^3] 478.516

Wing Volume [ft^3] 0.277

Foam Weight [lbf] 0.485

Wing Weight [lbf] 1.050

Φ = - 0.82 deg

Deflection = 2e-6 in

60 of 48

Wing Skin MaterialWing Skin Material

http://www.airfieldmodels.com/information_source/how_to_articles_for_model_

builders/finishing_techniques/apply_fiberglass_finish/index.htm

61 of 48

Material PropertiesMaterial Properties

Material Properties Table

 E-Glass

FiberS-Glass

FiberE-glass (Fabric)

Balsa Wood

Carbon Fiber

Polyurethane Foam

Density (lbs/in^3) 0.071 0.072 0.068 0.054 0.065 0.0046

Tensile Strength (ksi) 165 250 62.8 0.16 325 0.16

Shear Strength (ksi) 12.9 10 12.2 0.54 10.6 0.2

Longitudinal Young's Modulus (10^6 psi) 6 6.5 3.55 0.0094 21.3 0.0051

Transverse Young's Modulus (10^6 psi) 1.5 1.6 3.45 0.0094 1.5 0.0051

Shear Modulus (10^6 psi) 0.62 0.66 0.68 0.0085 1 0.00145

Poisson's Ratio 0.28 0.29 0.11 0.4 0.27 0.25

62 of 48

V-n DiagramV-n Diagram

Load Factor vs. Turn Radius for Different Velocities

0

5

10

15

20

25

30

35

0 10 20 30 40 50 60

Vertical Turn Radius [ft]

Lo

ad F

acto

r (n

)

30 [ft/s]

35 [ft/s]

40 [ft/s]

45 [ft/s]

50 [ft/s]

55 [ft/s]

60 [ft/s]

65 [ft/s]

70 [ft/s]

75 [ft/s]

80 [ft/s]

85 [ft/s]

90 [ft/s]

95 [ft/s]

100 [ft/s]

Design Point:

Vertical turn radius = 28 ft

Velocity = 60 ft/s

Load factor = 5

12

gr

Vn

63 of 48

Load Factor – Max LiftLoad Factor – Max Lift

2

2V

W

SCn L

10 20 30 40 50 60 70 80 90 1000

2

4

6

8

10

12

14Load Factor vs. Velocity

Velocity [ft/sec]

n max

64 of 48

Load Factor – Level TurnLoad Factor – Level Turn

0 10 20 30 40 50 60 70 80 900

2

4

6

8

10

12Load Factor vs. Bank Angle

Bank Angle [deg]

n turncos1n

65 of 48

Load Factor – Vertical TurnLoad Factor – Vertical Turn

0

50

100

150

0

50

100

1500

2

4

6

8

10n pu

ll up

Load Factor vs. Velocity and Vertical Turn Radius

Velocity [ft/sec]Vertical Turn Radius [ft]

12

gr

Vn

66 of 48

Wing CentroidWing Centroid

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4NACA 1408 Normalized Airfoil and Centroid Location

x/c

y/c

67 of 48

ComparisonComparison

I_xx_area_avg_error 22.70%

I_xx_skin_avg_error 6.79%

J_area_avg_error 23.81%

J_skin_avg_error 27.30%

Airfoil Tip Deflection

[ft] 1.386E-04

Ellipse Tip Deflection

[ft] 1.298E-04

Airfoil Tip Twist [deg] -1.045

Ellipse Tip Twist [deg] -0.820

68 of 48

D&C Appendix

69 of 48

D&C AppendixD&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

wfh

wfhhwfA

Lhh

L

Lachh

Lacac

CSS

ddCF

FCXSS

ddCXX

11

1

70 of 48

D&C AppendixD&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

S

SC

C

CC

b

zlCC

b

l

S

SKKC

C

CCCC

VVeffy

Veffy

WBFVyVy

VVVyVn

BBsRlNBn

wn

nnnnVBw

)(2

sincos

3.57

0All equations result in rad-1

71 of 48

D&C AppendixD&C Appendix

Open loop poles of aircraft yaw rate transfer function

Eigenvalue Damping Freq. (rad/s)

0.00e+000 -1.00e+000 0.00e+000

2.11e-001 -1.00e+000 2.11e-001

-6.22e-001 + 2.86e+000i 2.12e-001 2.93e+000

-6.22e-001 - 2.86e+000i 2.12e-001 2.93e+000

-5.46e+000 1.00e+000 5.46e+000

72 of 48

Appendix:Appendix:Control System Root LocusControl System Root Locus

Use of SISOTool to help determine the correct gain to use

73 of 48

AppendixAppendix

Control system closed loop poles: Eigenvalue Damping Freq. (rad/s)

0.00e+000 -1.00e+000 0.00e+000

2.81e-001 -1.00e+000 2.81e-001

-3.36e+000 + 2.16e+000i 8.40e-001 3.99e+000

-3.36e+000 - 2.16e+000i 8.40e-001 3.99e+000

-4.41e+000 1.00e+000 4.41e+000

-1.78e+001 + 2.18e+001i 6.32e-001 2.82e+001

-1.78e+001 - 2.18e+001i 6.32e-001 2.82e+001