I renewed my NAR membership a few months ago. And have not received my Sport rocketry magazine yet. Do you get the magazine with renewal? Or is it just for new members?
Yes, you receive Sport Rocketry when you renew your membership.
Your renewal may have happened 'between' issues. The Jan/Feb 2010 issue of Sport Rocktry was to have shipped on January 4th. If you paid extra for first class postage/shipping, you will receive it in the next 7-10 days. If you did not pay for the additional shipping, you can expect the magazine in 2-3 weeks.
Also, you can contact NAR HQ and ask about your subscription.