# Disc Eddy current brake Torque calculation [duplicate]

I have built a rotational Eddy brake in a small car, where I use gears to make the metal disc in the brake rotate faster or slower at will. I know that the braking torque is dependant on the rate of change of the magnetic flux linkage and therefore the faster the disc spins the stronger the brake force.

But I am unable to calculate the braking torque. I can't find a formula that joins the Rotational speed of the disc with the torque produced. I think I would first need a relation between rotational speed and magnitude of the eddy current produced. An then work with that to calculate magnetic drag. From which to obtain braking torque

I am currently lost. I think I have over researched and am unable to find something useful.

• Hello, and welcome to Stack Exchange. Congratulations on a very cool first question; unfortunately I have nothing to offer in the way of an answer. – Daniel Griscom Nov 22 '15 at 19:50
• It's a good question - but it was asked before on this site and I wrote an answer there. Obviously going from force to torque just requires multiplying by the radius of the disk. – Floris Nov 23 '15 at 12:22