forces acting on vehicle
GIVEN:- the maximum speed of the motor used in an electric scooter capable to run at 90 kmph, if the fixed gear ratio is 7 and tire size is 90/100 R10 53J
SPEED=90 kmph=25m/s
Code1 - 90/100 R10 53J
Code2 - 90/90 R18 51P
Gear Ratio (G) - 7
1) CALCULATIONS: READING THE DATA INSIDE GIVEN
CODE1: 90/100 R10 53J
Section Width (Ws) - 90mm = 0.09 m
Aspect Ratio - 100%
Section Height (Hs) - 0.09 m
Rim Diameter - 10 inch = 0.254 m
Load Index - 53 N
Speed Symbol - J
Calculating Tire Diameter. Dt = 2*Hs + Dr
Dt = 2*(0.09) + 0.254 Dt= 0.434m
Calculating Tire Radius: Rt = Dt/2
Rt = 0.217 m
Calculating angular velocity=(v/r)*G
= (25/0.217)*7
= 806.45 rad/sec
Calculating max. speed of the motor: vmax =w • r (r = Rt)
vmax. = 806.45*0.217
vmax. = 174.99 m/s
vmax. = 629.964 Kmph
READING THE DATA INSIDE GIVEN
CODE2: CODE2: 90/90 R18 51P
Section Width (Ws) - 90 mm = 0.09 m
Aspect Ratio - 90%
Section Height (Hs) - 0.081 m
Rim Diameter - 18 inch = 0.4572
Load Index- 51 N
Speed Symbol - P
Calculating Tire Diameter.
Dt = 29*hs + Dr
Dt = 2*(0.081) + 0.4572
Dt =0.6192m
Calculating Tire Radius:
Rt = Dt/2 Rt = 0.3096 m
angular velocity
w= (25/0.3090)*7
w= 56525 rad/sec
Calculating max. speed of the motor:
v2max. = w • r (r = Rt) v2max. = 565.251*0.3096
v2max. = 175 m/s
v2max. = 630 Kmph
Result: vlmax. = 629.964 Kmph ,v2max. = 630 Kmph The 10% reduction in aspect ratio and increase in the size of rim diameter does not lead to a significant change max. speed of the motor.
2)2) PROPULSION POWER:
Now, by considering all the forces acting on the vehicle
we will calculate propulsion power with the help excel calculator. Assuming there are no hill climbing actions, (Fhc = 0) Thus,
the Tractive Force: Ft = Frr + Fad
calculation on excel sheet
power output:-112.576 kw
3)TIRE PRESSURE REDUCTION: ASSUMING THE 15% REDUCTION IN TIRE PRESSURE LEADING TO TWICE THE INCREASE IN ROLLING RESISTANCE. BY KEEPING THE OTHER PARAMETERS UNCHANGED. DIFFERENCE OF TOTAL TRACTION POWER (PROPULSION POWER) = P_V1 - P_V2
difference after reduction in tire pressure=3.136 kw
4) range rover sports
Specifications:
a. Vehicle Type - Plug-in hybrid electric vehicle
b. Maximum Speed - 209 Kmph
c. Acceleration (0-100 kmph) - 8.5 sec
d. Capacity - 2997 (cc)
e. Maximum Power - 221/4000 (kW/rpm)
f. Gross Vehicle Weight - 3100 Kg
The Range Rover Sport Dragon Challenge demonstrates the powerful performance of the car at extreme conditions, climbing at Tianmen mountain with gradability angle of 45 Degree, with an average speed of 50-55 Kmph covering the 99 turns and 999 steps, completing the task in 22 mins 41 secs.