For the full skinney, follow the links thojo.

The short version is that combat is a game of scoreing points. You get points for launching on time, flying the entire round, cutting an opponents streamer (sorry, no points for cutting your own streamer), and returning with your own streamer.

20 points for getting in the air on time.
20 points for flying the entire round.
100 points for a cut
4 points per foot of your origional streamer (you start with 30 feet). (The streamer frequently streaches in the air, but there is a max of 120pts for your entire streamer)

A contest is flown in several "rounds", at least 4. At the end, the points are totalled up to determine the winner. The points are also totalled in to the RCCA National Points Standing (NPS) system that you can see on the www.rccombat.com site.

The result of the points system is that you can win a contest by not doing anything spectacular, but just being consistant and hanging on to your own streamer. In fact, the contest winner may never "win" a round, and they may not have the most cuts in the day either. Being consistant really matters.

An average over several rounds of 260, (launching on time + flying the whole round + 1 cut + keeping your streamer) will frequently place well at many contests. At the bigger contests with the best pilots, a round average of over 400 is frequently needed to win!

There are also ways to loose points for safety violoations in the air, but this post is getting long enough as it is