Gear Reduction Selection

Power Requirements against:

Fr: Wheel Resistance

FL : Air resistance

Fa: Acceleration resistance

Wheel Resistance= Rolling resistance + Slip Resistance + Road Resistance

Tr: Brake Torque

Assumption taken

mass of vehicle being=Mf

CALCULATIONS

Fr=fr*Mf*g*Cosαst     where αst=30˚

Fr=0.16*200*9.81*Cos 30

Fr=280N

R=313*9.81=3070.50N

Static Resistance=µR

=0.65*3070.5=1995.84N

Vmax=60kmph

= .221m

Air Resistance

FL:0.5ρCwAv2

Ρ=Air Density

Cw=Drag Coefficient

A=Area

V=velocity

FL =0.5*1.99*0.0315*(16.66)2

=0.52N

Fst=Mf*g *Sinαst

Putting the corresponding value

Fst=131.725N

Acceleration resistance:

Fa=m*a

=956N

Ftotal=2662.247

Power Required: Ftotal*v/(Nrpm*η)

1. nikhil singh

can you share a sample calculation of max torque which can be applied on wheels so that it doesn’t slip . Actually I know how to do it just want to verify as i am getting very low value. Pls reply soon I have to finalize my baja report

1. Baja Tutor

1.) Calculate normal force: F = M* 9.81 = X N
2) Multiply normal force by a friction coefficient – (Rolling resistance not static one, lets say its 0.6) and wheel radius: T = X * 0.6 * 0.4394 = Y Nm
3) Divide by number of wheels: T/4 = Z Nm.
Note : A BAJA buggy will have a different load on the front and rear wheels, so they have different required torques.

2. sushant shingare

can you give a sample calculation for calculating efficiency of transmission including all the resistances

3. Rohit Garg

hey,
you have calculated the aero drag at 60kmph and also considered the acceleration resistance, so when ur car is already at top speed, e.i. 60kmph than how can it accelerate?

4. Santosh Kumar.S

Hello mate…
In calculating Air resistance…..what do u infer by “area”… On what basis you’ve taken it as 0.0315..?