Cars and Automotive Design

When calculating V, why the division by 60'000?

Wouldn't V = pi x d x n already be the result you are looking for?

(But use 0.376m as diameter...)

Hi phil,

Thanks for the quick reply.

I have been following a video on youtube explaining the process and i have been following that.

https://www.youtube.com/watch?v=efLRsQIpO3Y

https://www.youtube.com/watch?v=h3-h0c2AJgA&t=559s

I have followed both videos and I am not sure what has gone wrong.

regards

yohann

in the video they divide the velocity by 12, because the conversion-ratio between feet and inches is 12.

When using metric just insert your SI Base units.

For a quick check you can always make a short unit check.

(eg. meters times 1/s = m/s)

also when using metric units there's this very nice formula for engine power:

P = (M x n) / 9550

P = Power in kW

M = Torque in N

n = speed (rotation) in 1/min

ahh, wait 60s per minute and 1000mm in a m --> 60'000. makes sense!

So do you know what I have done wrong then.

Unfortunately I don't see another problem.

You could work with the same formulas but with numbers where you know the resulting stress to check whether you're doing it right. If it works out your result should be correct as well.