FOUR SEAT LIGHT PLANEChris Hayes, Matt Mayo, Bryant Ramon

Table of Contents1) Title Page

2) Table of Contents

3) Problem Statement / Description

4) Requirements

5) Three-Views / Isometrics (Cessna 172 Skyhawk)

6) Three-Views / Isometrics (Cirrus SR22)

7) Three-Views / Isometrics (Cessna 172 Re-Design)

8) Chapter 1 - Design Proposal

9) Chapter 2 – Preliminary Estimate of Take-Off Weight

10) Chapter 3 – Wing Loading Selection

11) Chapter 4 – Main Wing Design

12) Chapter 5 – Fuselage Design

13) Chapter 6 – Horizontal and Vertical Tail Design

14) Chapter 7 –Engine Selection

15) Chapter 8 – Take-off and Landing

16) Chapter 9 – Enhanced Lift Design

17) Chapter 10 – Structural Design and Material Selection

18) Chapter 11 – Static Stability and Control

19) Chapter 12 – Cost Estimate

20) Chapter 13 – Design Summary and Trade Study

21) Regulatory Compliance

22) Performance Quote

23) Final Rendering of our model

24) Final Rendering of our model (cont.)

25) Conclusions

Problem Statement / Description

Your team works for Cessna and you’ve been charged with proposing a new design to replace/complement the Skyhawk. Your team will propose a new design that can out perform Diamond/Cirrus designs all with the prestigious Cessna nameplate. Your proposal should include a recommendation on 172 retirement, launching a replacement design, upgrading the 172 only or leaving the 172 as is and launching a new design.

RequirementsPerformance Item Altitude/Ambient Velocity/

MachFlaps Weight Requirements/

TargetsDesign Payload (Non-Expendable) ISA Vmax Clean Wo 1 Pilot / 3 pax

Passenger Allowance - - - - 250 lbs/paxCabin Length/Width/Height - - - - 12’/4’/4’Design Payload (Expendable) ISA Vmax Clean Wo 0

Design Range w/Max Payload Solve / ISA Vmax Clean Wo 800 nmDesign Time-on-Station w/Max Payload Solve / ISA Vmax / Vbe Clean Wo 0Stall Speed Sea Level / ISA Solve Clean Wo <45 nm/hrMax Cruise Speed = Max Mach Cruise Altitude / ISA Solve Clean Cruise >160 nm/hrAEO Takeoff Field Length Sea Level / ISA - Flaps Wo <1,800 ftOEI Takeoff Field Length (BFL) Sea Level / ISA - Flaps Wo n/aLanding Field Length Sea Level / ISA - Flaps Wo-(Wf/2) <1,500 ftAEO Rate-of-Climb Sea Level / ISA Vtakeoff Clean Wo >900 ft/minOEI Rate-of-Climb Sea Level / ISA Vopt Flaps Wo n/aGlide Slope (Cruise Altitude/2) / ISA Vopt Clean Landing <3 degMax Sustained Turn Rate Cruise Altitude / ISA Vopt Clean Cruise >2 deg/sMax Instantaneous Turn Rate Cruise Altitude / ISA Vopt Clean Cruise >2.5 deg/sService Ceiling Solve / ISA Vopt Clean Cruise >20,000 ftUnit Cost - - -   <$350,000Development Cost - - - - <$11M

Three-Views / Isometrics

• Cessna 172 Skyhawk

Source: http://www.the-blueprints.com/en/blueprints/modernplanes/cessna/18078/view/cessna_172_skyhawk/

Three-Views / Isometrics

• Cirrus SR22

• Source: http://servicecenters.cirrusdesign.com/TechPubs/pdf/POH/sr22-002/pdf/20880-002InfoManual.pdf

Cessna 172 Redesign

Design Proposal

• Re-Designing the Cessna 172 Skyhawk• Passenger allowance of 250 lbs/pax• Cabin Dimensions of 12’/4’/4’• Design Range (with Max Payload) of 800 nm• Faster cruise than Cirrus SR22

Preliminary Estimate of Take-off Weight

Assumptions(using Corke atmosphere model)• SFACT: 0.5280

• Corke Table 2.3• Lift-to-Drag ratio: 13.0

• Corke Figure 2.4• SFC: 0.7713

• Updated with Engine Spreadsheet

Benchmarking

Janes W0 Cessna Redesign W0

Del%

Cirrus SR22 3,600 (lb) 3,967.0 (lb) 10.2%heavier

Cessna 172 2,450 (lb) 3,967.0 (lb) 61.9%heavier

Design Weight Summary

Design Problems

Mission Analysis Summary     (W/Wo)        Weight  Parameter Symbol Value Fraction  Empty Weight (lb) We 2,094.6 0.5280  Payload (lb) Wp 1,000.0 0.2521  -Expendable Wpe 0.0 0.0000  -Non-expendable Wpne 1,000.0 0.2521  Fuel Load (lb) Wf 872.4 0.2199  -Mission Fuel Burned Wfb 823.0 0.2075  -Reserves Fuel Wr 41.2 0.0104  -Trapped Fuel Wtf 8.2 0.0021  Design Takeoff Gross Weight (lb) Wo 3,967.0 1.0000  Surplus Empty Wt. (lbs)   0.00  

Wing Loading Selection

Assumptions(using Corke atmosphere model)• Cl,max: 2.314083922

• Chapter 4 spreadsheet• Cd0: 0.0161

• Chapter 7 spreadsheet• e: 0.8

• Accepted value given by Corke• Takeoff Max Thrust: 906 lbs

• Calculate to obtain climb rate

Benchmarking

Jane’s W/S Cessna Redesign W/S Del%

Cirrus SR22 24.8 17.81 28.2%

Cessna 172 14.1 17.81 26.3%

Design Wing Loading Summary

Design Problems

Wing Loading Selection Summary      

           

  Design Wing Loading W/S (lb/f^2) 17.81   

           

No.Flight Regime Parameter Value Target Del%

1AEO Take-off S_TO (f) 945.8 1800.0 -47%

2Landing S_L (f) 1,119.9 1500.0 -25%

3Cruise Start S (f^2) 222.7   

4Cruise End H (f) 10,000.0   

5AEO Climb dH/dt (f/min) 731.1 900 -19%

6Acceleration n 7.149   

7Turn - Instantaneous psi_dot (deg/s) 7.270 2.5 191%

8Turn - Sustained psi_dot_act (deg/s) 7.259 2.0 263%

9Ceiling H (f) 36,937.4 20000 85%

10Glide Gamma (deg) 2.490 3 -17%

11Stall Speed Vstall (ktas) 47.6 45 6%

Main Wing Design

Assumptions(using Corke atmosphere model)• Aspect Ratio: 7.5

• JAWA 2013• LE Sweepback: 0

• Not required for light airplanes• Airfoil: NACA 2412

• Same airfoil as the Cessna 172S based on wikipedia

• Interference factor: 1• Corke Table 4.2

Benchmarking

Main Wing Design Summary

Design ProblemsCirrus SR22 Cessna 172 Cessna Redesign

Aspect Ratio 10 7.32 7.5

Taper Ratio 1 1

LE Sweep 0 0

Max (t/c) .28 .12 .12

Airfoil Description

Roncz NACA 2412 NACA 2412

CL,Max 1.7 1.5

b 40.87 ftMeff 0.250  cr 5.45 ft

ct 5.45 ftm.a.c. 5.4 ft     b 0.9682  

CLa 0.0863 1/deg

CLo 0.1726  

atrim 0.54 deg

CLtrim 0.2192  k 0.0531  CD 0.0133  L/D 16.48  

Total Drag 185.9 lbf

Fuselage Design

Assumptions(using Corke atmosphere model)• Inverse Fineness: 7.11

• Corke Table 5.11• Max Diameter: 4.5

• Design Driver• Interference factor: 1

• Corke page 107• Fuselage shape: Elliptical Cylinder

• subsonic

Benchmarking

Fuselage Design Summary

Design ProblemsCirrus SR22 Cessna Re-Design Del%

Inverse Fineness 5.4 7.11 31.7%

Max Diameter 4.8 4.5 6.3%

Total Drag 90 61.3 31.9 %

Cessna 172 Cessna Re-Design Del%

Inverse Fineness 6 7.11 18.5%

Max Diameter 4.75 4.5 5.3%

Total Drag 37.5 61.3 63.5%

Viscous Drag Calculations: Elliptic Cylinder Fuselage Shape

x/L x (ft) H (ft) W (ft) P (ft) Sw(ft^2) Rex CF Drag (lbf) Volume (ft3)0.00 0.0 1.00 1.00 3.10.10 3.2 2.50 2.50 7.9 25.1 4.5E+06 3.40E-03 6.4 8.20.20 6.4 4.50 4.50 14.1 45.2 9.0E+06 3.04E-03 10.2 31.60.30 9.6 4.50 4.50 14.1 45.2 1.4E+07 2.85E-03 9.6 50.90.40 12.8 4.50 4.50 14.1 45.2 1.8E+07 2.72E-03 9.2 50.90.50 16.0 4.50 4.50 14.1 45.2 2.3E+07 2.63E-03 8.8 50.90.60 19.2 4.00 4.00 12.6 40.2 2.7E+07 2.56E-03 7.6 45.40.70 22.4 2.40 2.40 7.5 24.1 3.2E+07 2.50E-03 4.5 26.30.80 25.6 1.40 1.40 4.4 14.1 3.6E+07 2.45E-03 2.6 9.30.90 28.8 0.90 0.90 2.8 9.0 4.1E+07 2.41E-03 1.6 3.41.00 32.0 0.50 0.50 1.6 5.0 4.5E+07 2.37E-03 0.9 1.3

Totals: 298.6 61.3 278.1

Horizontal and Vertical Tail Design

Assumptions(using Corke atmosphere model)• Aspect Ratio: 1.3 vertical, 3 horizontal

• Corke Table 6.5 in range• Taper Ratio: 0.5, 0.5

• Corke Table 6.5• LHT / LVT: 18 ft / 18 ft

• Corke page 126

Benchmarking

Tail Design Summary

Design ProblemsCirrus SR22 Cessna

Redesign

Aspect Ratio 1.3/3.0

Taper Ratio 0.5/0.5

LE Sweep 35/15

Max (t/c) 0.35/0.35

Airfoil Description NACA 63-006

CL,Max 0.8/0.8

Tail Design Summary    Total   VT TE  Drag (lbf) Del% Sweep (deg)Conventional 56.9 Base 10.6T-Tail 54.3 -4.6% 10.6Cruciform 56.1 -1.5% 10.6H-Tail 58.1 2.1% 10.6V-Tail 53.6 -5.9% 10.6Inverted V-Tail 53.6 -5.9% 10.6Y-Tail 55.8 -1.9% 10.6Twin Tail 59.8 5.1% 10.6Control Canard 56.9 0.0% 10.6Lifting Canard 56.9 0.0% 10.6         Main Vertical Horizontal  Wing Tail Tail

Airfoil Section   NACA 63-006 NACA 63-006Max Thickness, % 0.120 0.060 0.060LE Sweep, deg 0.0 35.0 15.0Aspect Ratio, -   1.300 3.000dCL/da, 1/deg   0.0320 0.0594

Engine SelectionAssumptions(using Corke atmosphere model)

Benchmarking

Engine Selection Summary

Design Problems

Design Parameters Cessna Redesign

Gross Weight 3,967.0 lbs

Reference Wing Area 222.7 ft^2

Wing Loading 17.81

Cruise Altitude 10,000 ft

Cruise Speed/Mach 159.5/0.25

Bleed 0.02

Reference Engine PT6A-50

Engine Scale Factor 1.0

Scaling Methodology Eqns. 7.8-7.11

Engine Cirrus SR22 Cessna 172 Cessna Redesign

Power 160 945

SFC 0.4313 0.7494

Weight 430.72 lbs 258 lbs 215.6

Length 38.43 in 33.6 in 39.6 in

Diameter Width: 18 inHeight: 25 in

Width: x inHeight: x in

Propeller

Diameter 6.667 ft 6.25 ft 7 ft

Number of Blades 3 2 2

Engine Selection Summary      

    Value Units

Number of Engines   1 -

Uninstalled Engine Power, SLS ISA Max   945.0 shp/eng

Reference Engine   PT6A-50 -

Engine Scale Factor   1.000 -

Type of Engine    Turboprop -

Ave. SFC, @ Design Cruise    0.7494 lbm/hr/shp

Engine Weight    215.6 lbf/eng

Engine Length    39.6 in

Engine Max Diameter    19.6 in

Propeller Diameter   7 ft

# of Blades   2 -

Take-off and LandingAssumptions(using Corke atmosphere model)

Benchmarking

Takeoff and Landing Summary

Design Problems

Cirrus SR22 Cessna 172 Cessna Redesign

AEO field length 961/1061

OEI field length - - -

Landing field length 961/1061

Design Parameters Cessna Redesign

Gross Weight 3274

Reference Wing Area 222.7 ft^2

Wing Loading 9.21

Gear Frontal Area 151.58 ft^2

Takeoff/Landing Rationale

Flap deflection angle 30/60 Adjust lift curve

Cl_max 1.1/1.55

Obstacle Height 50/50

Friction Coefficient 0.4 (Roll0/0.5 (Brake)

Takeoff and Landing Summary           Design Gross Weight lbf 3967  Altitude ft 0  Engine Thrust lbf/eng 906  Stall Speed nm/hr 47.7         Field Lengths      AEO Takeoff ft 2,021  OEI Takeoff ft #NAME?  Landing ft 2,231         Regulatory Compliance    AEO, Gear Up Vy ft/min 704  OEI, Gear Up Vy ft/min 0  OEI, Gear Up G % 0.0%  OEI, Gear Down G ft/min 0.0%

Enhanced Lift Design

Assumptions(using Corke atmosphere model)

Benchmarking

Wing Platform Plot

Design ProblemsCirrus SR22 Cessna 172 Cessna Redesign

Flap type Plain plain plain

Flap Chord/ Wing Chord 3.6028/7.2

Flap Span/ Wing Span 21.617/54.04

S_wf/S_w 194.7/389.4

0 3 6 9 12 150

3

6

9

12

15

Wing Planform

Axial Position, (ft)

Win

g H

alf

Sp

an,

b/2

, (f

t)Flap Design Summary                 

    Design Units    Type of TE Flaps plain -    LE Flaps No -    Flap Area / Wing Area, Swf/Sw 0.50 -    Flap Deflection Angle, df 40.00 deg    Flap Chord / Wing Chord, cf/c 0.40 -  

  Flap Span / Wing Span, bf/b 0.50 -  

  CL,max 2.31 -  

  DCDo, flaps 0.0863 -  

         

Structural Design and Material Selection

V-n Diagram

Structure Material Summary

Wing Platform Plot

Design ProblemsStructure/Material Summary        Wing Wing Fuselage Fuselage  Skin Spar Skin LongeronsX-Section Airfoil I Beam Hollow Ellipse Hollow Circle

Material GroupAluminum

Alloy Alloy Steels Aluminum AlloyAluminum Alloy

Material 2024-T3 (clad)4130

Normalized 2024-T3 (clad) 2024-T3 (clad)Tension (W1/W2)t 1.000 1.728 1.000 1.000Compression (W1/W2)c 1.000 2.447 1.000 1.000Bending (W1/W2)b 1.000 2.211 1.000 1.000# of Wing Spars X 1 X XSpar Deflection (in.) X 10.00 X XSpar Height < Wing Thickness ? X YES X X# of Bulkheads X X X 14Bulkhead Spacing (in.) X X X 28.30# of Longerons X X X 8Longeron Height < Fuse. Wall X X X YES

Static Stability and Control

Final Weight Breakdown

Rudder Design

Static Stability & Control Summary

Design Problems

Weight Summary                GeneralComponent Symbol Fighter Transport AviationWing Wwing 631 512 487Horizontal Tail Wh-stab 67 18 26Vertical Tail Wv-stab 20 41 26Fuselage Wfuse 794 888 303Main Gear Wmain lg 112 77 180Nose Gear Wnose lg 59 30 32Engine(s) Weng 553 553 595Remaining Components Wrem 674 674 555Empty Weight We 2,910 2,793 2,204Design Gross Weight Wo 3,967 3,967 3,967Empty Weight Fraction We/Wo 0.734 0.704 0.556

Static Stability & Control Summary  Static Margin ValueComments   -Center of Lift 0.3553xcl/L   -Center of Gravity 0.3401xcg/L   -Static Margin @ Wcr, start 9.0%stable   -Dtrim / Dtotal 0.146Dtrim high, See Corke Page 279       Stability Coefficients       -Longitudinal, Cm,a -0.0019stable Corke: -1.5<Cm,a<-0.16 -Lateral, CL,b -0.1715stable   -Directional, Cn,b 0.1715stable Corke: 0.08<Cn,b<0.28       Rudder Area 2.3ft2  

0 1 2 3 4 5 60

1

2

3

4

5

V-Stabilizer Planform

Axial Position, (ft)

V-S

tab

Sp

an,

(ft)

Cost Estimate

Cost Estimate Summary

Proposed Cost vs. Requirement

Pie Chart (1986 CER’s)

Design Problems

Cost Estimate Summary     Year 2013Number of Development Aircraft 2Number of Production Aircraft 5300Production Rate (per month) 50Amortization Period (# of ac) 4000

Initial Unit Cost (1986 Model) $689,852Final Unit Cost (1986 Model) $661,368Initial Price Markup 4%

Profit (%) 10

C_E ($)5%

C_D ($)1%

C_ML ($)47%C_MM ($)

25%

C_T ($)5%

C_QC ($)7%

C_EN ($)1%

C_P ($)9%

1986 CERs Cost Estimate in 2013Dol-lars

Proposed Cost Requirement Del %

$661,368 $350,000 89.0%

Trade SummaryDesign Summary

Trade Study Results

Trade Study• Wanted to see the effect of a more

efficient engine or increased cruise Mach would have on range

172 Re-Design Cessna 172 Cirrus SR22

Weights

W_TO (lb) 3967 2189.4 2077.8

W_S 2094.6 1402.2 1243.3

W_F (lb) 872.4 188.2 234.5

W_P (lb) 1000 599 600

s_fact 0.528 0.6404 0.5984

Wing

S (ft^2) 222.7 139.6 145

b (f) 40.87 36.08 38.33

W/S (lb/ft^2) 17.81 15.68 22.07

Fuselage

L (f) 32 27.2 26

H(f) 7 8 8.92

Engines

# of 1 1 1

T_max (lb) 906? ?

T/W 0.2284? ?

Takeoff/LandingS_TO (ft) 2021.1 1630 1756

S_L (ft) 1324.6 1335 1178

0.4 0.6 0.8 1 1.2 1.4 1.6

0.0

200.0

400.0

600.0

800.0

1000.0

1200.0

1400.0

Specific Fuel Consumption vs Range (nm)

Range (nm)

Specific Fuel Consumption (lb/(lbf·h))

Ra

ng

e (n

au

tica

l M

iles

)

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

720

740

760

780

800

820

840

860

880

Cruise Mach vs Range (nm)

Cruise Mach

Ra

ng

e (n

au

tica

l m

iles

)

Regulatory and Design compliance

Your DesignRegulatory Compliance Corke Reference StatusCertification (FAR Part 23)Velocities V_TO>1.1Y_Stall CompliantTakeoff Climb Gradient 300 fpm @ sea level compliantRolling Friction n/a n/aObstacle Height 50 feet n/aEmergency Exits 1 type IV compliantMax Load Factor load factor <3.1 compliant

Design ComplianceAirfoil Cross Section, Taper, Sweep Sections 4.1-4.3 compliantCrew Sight Lines Table 5.8, page 95 compliantFuselage Volume Section 5.1 compliantTail Geometry Tables 6.1-6.6, pages 123-128 compliantTail Geometry – Aft VT TE Sweep<20 deg page 136 compliantTail Placement – Stall Control Figure 6.9, page 129 compliantTail Placement – Spin Recovery Figure 6.10, page 131 compliantPropeller Tip Speed/Mach < 0.85 page 152 compliantLongitudinal Static Stability Equation 11.26 compliantDirectional Static Stability Equation 11.45 compliantTrim Drag Equation 11.61 compliant

Performance Quote

Requirements/ ProposedPerformance Item Targets Design Delta% Cessna 172 Cirrus SR 22

-Design Payload (Non-Expendable) 1 Pilot / 3 pax 4 n/a 4 4-Passenger Allowance 250 lbs/pax 250lbs/pax n/a 250 250-Cabin Length/Width/Height 12’/4’/4’ (192 ft^3) 194 ft^3 1% 158 ft^3 184 ft^3-Design Payload (Expendable) 0 0 n/a 0 0-Design Range w/Max Payload 800 nm 800 nm 0% 640 nm 400 nm-Design Time-on-Station w/ Payload 0 0 n/a 0 0-Stall Speed <45 nm/hr 47.6 ktas -5.7% 48 ktas 60 ktas-Max Cruise Speed = Max Mach >160 nm/hr 158.5 ktas -0.9% 124 ktas 183 ktas-AEO Takeoff Field Length <1,800 ft 2021.1 ft 1630 ft 1756 ft-OEI Takeoff Field Length (BFL) n/a n/a n/a n/a n/a-Landing Field Length <1,500 ft 1324.6 ft 11.7% 1335 ft 1178 ft-AEO Rate-of-Climb >900 ft/min 704 ft/min 730 ft/min 1270 ft/min-OEI Rate-of-Climb n/a n/a n/a n/a n/a-Glide Slope <3 deg 2.49 deg 17% 6.34 deg 5.95 deg-Max Sustained Turn Rate >2 deg/s 5.64 deg/s 182% 22.2 deg/s 17.6 deg/s-Max Instantaneous Turn Rate >2.5 deg/s 7.27 deg/s 190.8% 13.8 deg/s 11.11 deg/s-Service Ceiling >20,000 ft 36,900 ft 84.5% 14,000 ft 17,500 ft-Unit Cost <$350,000 $689,850 97.1% $364,000 $664,900-Development Cost <$11M $113,900,000 -935.5% $68,200,000 $141,800,000

Final Rendering of our model

Final Rendering of our model (cont.)