How do I discipline my 15 month old son?

Ok, I have posted this question already, but there was a typo in the headline...My problem is my 15 month old son's tantrums. He will hit me and bite and kick me when he doesn't get his way. He trows himself down and kicks and screams. I have tried to talk to him, I have tried saying no...I have tried time out...Nothing seems to work. My mother and my in-law tell me to him on the but lightly to get him to understand cause and effect, but I don't know how I feel about . I have heard so many people say that it hurts your child mentally. I am at the end of my rope, and I don't know what to do. Any suggestions?