Team Thunderbirds designed and constructed an all-terrain utility vehicle called the Trendnought that uses two treads to traverse various terrains such as snow, mud, grass and gravel. The team selected a Briggs & Stratton 306cc air-cooled gasoline engine and Mahindra Alfa transmission for the vehicle. An analysis of the vehicle's performance in different gears was presented, including tractive force, acceleration, speed and resistance calculations. The total estimated cost of the vehicle project is Rs. 3,65,000, of which Rs. 60,000 is allocated for the engine and transmission.

1. Project by:
Team Thunderbirds
(SAE BAJA 2015)

2. Thunderbirds set out to design and construct
an all-terrain utility vehicle. The team’s vehicle
the trendnought ,has two treads to allow it to
traverse a wide variety of terrains such as
snow, mud ,grass and gravel.

3. BRIGGS AND STRATTON
Briggs & Stratton is the world's largest manufacturer of air-cooled
gasoline engines primarily for outdoor power
equipment. Current production averages 11 million engines
per year.
Briggs & Stratton engines are commonly used on lawnmowers.

4.  Displacement [cc] = 306
 Bore [mm] = 82
 Stroke [mm] = 58
 Weight [kg] = 25
 Oil Capacity = 1.1
 Compression Ratio = 8.0 to 1

5. MAHINDRA ALFA
 The Alfa is a three wheeler goods carrier
designed to make the loading, transportation,
and unloading of small cargos easier.
 Mahindra equipped the Alfa with the largest
and strongest cargo box yet at 24.5 cubic
feet, and then adapted the structure to
handle oversize loads.

6.  Engine Type = 4-stroke, Single Cylinder, air cooled diesel
engine
 Displacement = 395.00 CC
 Maximum Power = 5.51 KW @ 3600 rpm
 Maxiumum Torque = 16.7 Nm @ 2200-2800 rpm
 MaxSpeed = 53 Kmph
 Transmission = Constant Mesh
 Clutch = Multi Plate Wet Clutch
 Gearbox = 4-speed

8. Mechanical
The engine and power train option that was considered was a
mechanical gearing system powered by an internal combustion
engine. While the mechanical system can’t provide the zero-turn
capabilities as simply as hydraulic or electric systems can.

9.  Primary gear ratio=2.86
 Secondary gear ratio=2.38
 Final gear ratio=primary gear ratio*secondary gear
ratio*individual gear ratio
Gear Individual Gear ratio Final gear ratio
1 4.62
31.45
2 2.75
18.70
3 1.67
11.40
4 1.08
7.35
Reverse 8.09
55.05

10.  TORQUE=Maximum torque by engine*final
gear ratio
Gear Torque(N)
1 587.80
2 349.50
3 213.06
4 137.37
5 1028.88

11.  Radius of wheel=0.317m
 Force on wheel=torque/radius
Gear Torque(N) Radius(m) Force(N)
1 587.80 .317 1854.25
2 349.50 .317 1102.52
3 213.07 .317 617.94
4 137.37 .317 433.34
Reverse 1028.88 .317 3245.67

12.  RPM =Engine rpm/final gear ratio of different
gear engine rpm=3800
Gear Engine rpm Final gear ratio rpm Rps=rpm/60
1 3800 31.45 120.82 2.01
2 3800 18.70 203.20 3.38
3 3800 11.40 333.33 5.55
4 3800 7.35 517.00 8.61
reverse 3800 55.05 69.02 1.15

13.  Circumference=2흅r
 r=0.314
Gear Speed=rps*2 pie r in m/s
1 4.07
2 6.74
3 11.05
4 17.15
Reverse 2.28

14.  Aerodynamic drag=0.5 *p*A*V*Cd
 A=frontal area of vehicle=1.0966
 Cd=coefficient of drag=0.6
Gear Aerodynamic drag
1 6.33
2 17.93
3 48.27
4 116.13

15.  Rolling resistance =mg*Crr
 m=mass of vehicle=250kg
 g=accelaration due to gravity
 coefficient of rolling resistance=0.15
 total resistance =drag+rolling resistance
Gear Rolling resistance Aerodynamic
resistance
Total resistance
1 367.5 6.33 373.83
2 367.5 17.93 385.43
3 367.5 48.27 415.77
4 367.5 116.13 483.63

16.  Tractive force =force on wheel-total
resistance
Gear Force on wheel(N) Total resistance Tractive force(N)
1 1854.25 373.83 1480.42
2 1102.53 385.43 717.10
3 617.94 415.77 202.17
4 433.34 483.63 50.34

17.  Acceleration=tractive force/weight of vehicle
Gear Tractive force Acceleration Time taken
1 1480.42 6.02 0.66
2 717.10 3.02 2.32
3 202.17 1.16 4.36
4 50.34 1.08 11.34

18. Components Cost
Frame & Body 40,000-/
Suspension 20,000-/
Wheels & Tires 50,000-/
Steering 10,000-/
Breaks 15000-/
Engine & gearbox 60000-/
Instruments & wiring 10000-/
Driver accessories 50,000-/
Logistics & travel 40,000-/
Promotion & merchandise 20,000-/
Competition fees 50,000-/
Total 3,65,000-/
Engine & gear
Total Rs3,65,000

19. Engine & Gearbox:
Standard B&S engine, Mahindra Alpha Transmission.
Components Cost
B&S Engine 35,000
Transmission 19,000
Labour Cost 6,000
Total 60,000

20.  It is used to get various speeds in different load
conditions.
 It increases fuel efficiency.
 Increases engine efficiency.
 Need less power input when operated manually.
 They are more practical when there is a space
limitation.

21.  Robust transmission and longer gearbox life.
 Best suited for Briggs and Stratton engine.
 Compact and easily available in the market.
 Data of Specification and features are easily
available.

22.  www.bajasaeindia.org/
 www.irdindia.in/journal_ijmer/pdf/vol1_iss1/17
 www.mahindrasmallcv.com/bolero_alfa_passenge
r_diesel
 www.grabcad.com/library/briggs-and-stratton-
10hp-engine-for-baja-sae
 www.briggsandstratton.com
 www.mahindrajhbsouth.co.za/mahindra-alfa-specifications/
 grabcad.com/library/mahindra-alfa-champion-gearbox-
1

23. Thank you!