1

Structures 2 PDRStructures 2 PDR

Ashley Brawner

Neelam Datta

Xing Huang

Jesse Jones

Team 2: Balsa to the Wall

Matt Negilski

Mike Palumbo

Chris Selby

Tara Trafton

2

OverviewOverview

Weight determination Fuselage and tail Analysis of wing loads Wing structure

3

CATIA ModelCATIA Model

4

CATIA ModelCATIA Model

Component locations based on previous CG calculations

Will provide more accurate CG value Will lead to accurate moments and

products of inertia

5

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

6

V-n DiagramV-n Diagram

2

2V

W

SCn L

dashdive VV 25.1

20 40 60 80 100 120

-4

-2

0

2

4

6

Load Factor vs. Velocity

Velocity [ft/sec]

n

2

2V

W

SCn L

Maximum Design Load Factor = 7.5

7

Simplifying AssumptionsSimplifying Assumptions

Modeled lift with elliptic distribution Approximated airfoil as ellipse for

analysis

0 0.2 0.4 0.6 0.8 1-0.1

0

0.1NACA 1408 Normalized Airfoil and Elliptic Approximation

x/c

y/c

8

Discretized WingDiscretized Wing

00.5

11.5

22.5

-0.50

0.51

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

Chord [ft]

Exact Wing Geometry

Span [ft]

Thi

ckne

ss [

ft]

9

Bending LoadBending Load

0 0.5 1 1.5 2 2.50

2

4

6

8

10

12Elliptic Lift Distribution and Discretized Approximation

Distance from Root [ft]

Lift

[lb

f]

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]

10

Bending LoadBending Load

I

Mybending 33

4tbtaabIellipse

t = skin thickness

y = vertical distance from neutral axis

M = bending moment

I = moment of inertia

t = 0.00025 in

11

Twisting AnalysisTwisting Analysis

cSCVT m2

2

1 dsGA

qt2

A

Tq

2

• T = Torque

• Cm = Moment Coefficient

• c = Chord length

• q = shear flow

• A_bar = Airfoil cross-sectional area

• theta = twist angle/unit length

12

Twisting AnalysisTwisting Analysis

0 0.5 1 1.5 2 2.5 3-0.035

-0.03

-0.025

-0.02

-0.015

-0.01

-0.005Torque vs. Distance from Root

Distance from Root [ft]

Tor

que

[lb-f

t]

13

Wing Skin MaterialWing Skin Material

Fiberglass Thickness vs. Cloth Weight

y = 0.0015x

R2 = 0.9851

0

0.002

0.004

0.006

0.008

0.01

0.012

0 2 4 6 8

Fiberglass Cloth Weight [oz]

Fib

erg

lass

Clo

th T

hic

knes

s [i

n]

Known Values

weight [oz] thickness [in]

3 0.0046

4 0.0059

6 0.0093

7.5 0.0107

http://www.shopmaninc.com/cloth.html

E-glass/Epoxy

14

Wing Skin MaterialWing Skin Material

http://www.deltronix.net/cgi/acp_display.exe

Available Materials

weight [oz] thickness [in] cost per square yard

0.5 0.00075 $6.50

0.58 0.00087 $6.00

0.73 0.001095 $6.50

1.4 0.0021 $4.25

2 0.003 $4.50

2.3 0.00345 $5.00

15

Wing Skin MaterialWing Skin Material

Wing Area [in^2] 1465.078

Wing Area [yd^2] 1.130

Fiberglass Weight [lbf] 0.035

Epoxy Weight [lbf] 0.071

   

Wing Volume [in^3] 478.516

Wing Volume [ft^3] 0.277

Foam Weight [lbf] 0.485

Wing Weight [lbf] 0.591

With 0.5 oz E-glass/Epoxy

16

Wing Skin MaterialWing Skin Material

http://www.airfieldmodels.com/information_source/how_to_articles_for_model_builders/finishing_techniques/apply_fiberglass_finish/index.htm

17

SummarySummary

Lots of work still to be done… Wing skin will be 0.5 oz E-glass/Epoxy Current weight is approximately 0.6 lbf

Questions?

18

Questions?Questions?

19

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

20

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

21

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

22

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

23

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

24

Load AnalysisLoad Analysis

25

CG ApproximationCG Approximation

Team 2 - Weight Distribution

0.00

0.50

1.00

1.50

2.00

2.50

0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00

Distance from Nose (in.)

Wei

gh

t (l

bs)

Structure

Speed Controller

Batteries

Motor

Payload

Gyro

Tail Servos

Receiver

CG

26

CG ApproximationCG Approximation

BALSA

Component weight (lb) x pos (in.) y pos (in.)

Structure 2.26 15.04 0.81

Speed Controller 0.26 6.00 1.34

Batteries 1.25 2.00 1.34

Motor 0.59 5.00 1.34

Payload 1.00 3.00 -0.50

Gyro 0.01 3.50 1.75

Tail Servos 0.08 7.50 0.54

Receiver 0.04 3.50 1.00

Total Weight 5.50    

CG   8.15 0.77

Aerodynamic Center   9.26 1.34