3D Printed Model: Scale 1:18

INTRODUCTION

Objective: Study the aerodynamics of the Baja car and reduce its drag coefficient to improve performance.

Marvin Bertin, Maximilien Brodel, Kieran Mak, Rahul Rughani

• Problem: the firewall on the Baja vehicleproduces significant drag and slows the car.

• Objective: reduce the drag from the firewalland improve overall performance by designingand manufacturing flow optimized bodypanels that integrate seamlessly onto thevehicle.

• Aerodynamics have never been investigated by McGill Baja.• Other successful teams have added streamlined panels.• Streamlining of trucks could be a source of inspiration as they too

have an abrupt aerodynamic profile.

BACKGROUND

CONCEPT GENERATION

CONCEPT EVALUATION

Fast Diagram Summary

Primary Function Secondary Function Evaluation Criteria Material Criteria

• Reduce drag coefficient

• Minimize weight gain• Unobtrusive with

current car design• Easily Maintained

• Streamline vehicle profile

• Minimal body panel size• Structurally supported• Access of components• Compatible with car

frame• Removable panels

• Durable• Lightweight• Smooth surface• Strength• Flexibility• Thin• Water & mud

resistant

CFD ANALYSIS

Concept Drag (N) % Change Drag Lift (N) % Change Lift

Datum (MB14) 258.2 NA -110.0 NAMB15 (Baseline) 229.8 -10.99 % -93.5 +15.01 %Concept 0 229.9 -10.94 % -95.0 +13.59 %Concept 1 262.3 +1.58 % -106.6 +3.06 %Concept 2 243.2 -5.81 % -107.5 +2.28 %Concept 3 196.2 -24.00 % -61.7 +43.89 %Concept 4 233.0 -9.75 % -89.3 +18.76 %

Concept 1

Concept 2

Concept 3

Concept 4

WIND TUNNEL TESTING

0.95

1

1.05

1.1

1.15

1.2

1.25

40,225 46,929 53,633 56,986 60,338 63,690 67,042

Dra

g C

oef

fici

en

t

Reynolds Number

Drag Coefficient vs Reynolds Number

Baseline

Flat Panels

Curved Panels

Roof Scoop &Curved Panels

Concept Average Drag Coefficient

% difference with baseline

Baseline 1.160 -

Flat Panels 1.116 - 3.79%

Curved Panels 1.105 - 4.74%

Roof Scoop & Curved Panels

1.173 + 1.12%

FINAL CONCEPT

Concept 3 (curved panels) obtained best results in CFD and wind tunneltesting

Concept 150 ft accel.Accel time

saved Lap time Lap time saved

MB15 (base car) 5.9 s - 76.12 s -

MB 15 + Aero Panels 5.79 s 0.11 s 74.56 s 1.56 s

Performance improvement is evaluated with a Matlab drive train simulationprogram

Over 60 laps, time saved is 1 mn 34 s

MANUFACTURING / FASTENERS

CONCLUSION

Carbon Fiber Panel Manufacturing

A&P Technologies

+/- 45° biaxial fabric

Open mold wet layup with resin

5 plies

Vacuum hold, no curing

Material Requirements: Lightweight, Durable

D8 DZUS® PANEX Quarter-Turn Fasteners, size 6

Attach panels to chassis

Quarter turn: easily removable, tool free

Durable: steel plated with chrome

D8 grade, size 6: high ultimate torque and cyclic durability

• Results showed improved performance with limited streamlining. Therefore furtheraerodynamic optimization of the Baja is worthwhile.

• CFD determined that adding a roof, as other teams have done, would hurtperformance.

• Panel design was limited by several constraints. Particularly, engine must be easilyaccessible. Also, no parts should stick out of the frame as they could break uponimpact. Final design was best possible with constraints in mind.

Next step: Testing on finished car

Recommendations:

Consider aerodynamics early on in design process of car. Next frame should be builtto integrate streamlining elements, instead of adapting panels to an existing frame.

In the future, optimize flow over front of the car.

Department of Mechanical Engineering2014-2015 Mech Eng Design Project

Baseline

Final Concept

CFD Results

ACKNOWLEDGMENTS

The authors thank McGill Baja Racing, its carbon fiber sponsor A&P Technologies as wellas Linus Lehnert, Jasmin de Campos, Alex Marotta and the McGill machinist team.