Quote:
Originally Posted by Gonzo
Indeed, when I tried to calculate it, I got surprisingly very low numbers as well.
Acceleration in 3 sec:
Wheels:
I = 1/2 * 0.1 kg * (0.045 m)2
= 1.0125 *10exp-4 kgm2
a = 174,44 rad/sec2
T = I * a
= 0.0176 Nm
"Weight" from inertia wheels at 275mm:
0.0176 Nm / 0.275 m = 0.064 N or 6.5 g
Motor:
I = 1/2 * 0.1 kg * (0.007 m)2
= 2.45 *10exp-6 kgm2
a = 1744,43 rad/sec2
T = I * a
= 0.00427 Nm
"Weight" from inertia motor at 275mm:
0.00427 Nm / 0.275 m = 0.0155 N or 1.5g
But an acceleration in 3 seconds is a little bit slow in my opinion. Especially in the air, I think it's at rev in 0.5 sec at the most.
Also there must be an extra force playing on this matter besides inertia: think of a 4WD car that can make a backflip by holding the throttle open. At a certain point the wheels are at speed, but it seems they keep on helping flip the car. This cannot be pure inertia, because inertia only works when speed changes. It must be friction with the air of the wheels. So I think mechanical losses in the motor can have an effect too.
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My figures are slightly different because I assumed that all the mass of the wheel and tyre is at a radius of 45mm, wheras you have modelled the tyres as a 45mm cylinder of uniform mass, which halves the inertia. - The real answer will be somewhere between the two.