This document summarizes an engineering project to reduce drag on a Baja racing vehicle through aerodynamic design improvements. The team aimed to reduce drag from the firewall by designing and manufacturing flow-optimized body panels. Several panel concepts were evaluated through computational fluid dynamics (CFD) analysis and wind tunnel testing. The curved panel concept achieved the best results, reducing drag by 4.74% compared to the baseline design. Time trials estimated this would save over 1 minute of lap time over 60 laps. The curved panels were manufactured from carbon fiber and attached with quick-release fasteners. The project concluded aerodynamic optimization was worthwhile and recommended considering aerodynamics earlier in future vehicle designs.

1. 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 vehicle
produces significant drag and slows the car.
• Objective: reduce the drag from the firewall
and improve overall performance by designing
and manufacturing flow optimized body
panels that integrate seamlessly onto the
vehicle.
• 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 NA
MB15 (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
DragCoefficient
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 tunnel
testing
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 simulation
program
 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 further
aerodynamic optimization of the Baja is worthwhile.
• CFD determined that adding a roof, as other teams have done, would hurt
performance.
• Panel design was limited by several constraints. Particularly, engine must be easily
accessible. Also, no parts should stick out of the frame as they could break upon
impact. 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 built
to integrate streamlining elements, instead of adapting panels to an existing frame.
 In the future, optimize flow over front of the car.
Department of Mechanical Engineering
2014-2015 Mech Eng Design Project
Baseline
Final Concept
CFD Results
ACKNOWLEDGMENTS
The authors thank McGill Baja Racing, its carbon fiber sponsor A&P Technologies as well
as Linus Lehnert, Jasmin de Campos, Alex Marotta and the McGill machinist team.