Thanks for that. The size of the motor did rather surprise me. But I think there is a mistake in this sum > t =3D m*r^2*a =3D 5kg * 1m^2 * 5/3*pi rad/sec^2 =3D 25/3 * kg*m^2 / sec^= 2 =3D > 25/3 N * m =3D 8.33 N*m > You are a factor of pi short __________________________________________ David C Brown 43 Bings Road Whaley Bridge High Peak Phone: 01663 733236 Derbyshire eMail: dcb.home@gmail.com SK23 7ND web: www.bings-knowle.co.uk/dcb --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .