Junkyard Wars was a successful sport/reality show that started in the UK in 1998 and came to America a couple of years after. It had 14 rounds in total counting the "Junkyard Mega Wars"
The show is about 2 teams that have to build a machine or vehicle (like a cannon, a raft, a glider, etc) only with junk. Then, each machine will be tested in a competition. The team that builds the best machine will advance to the next round.
Each team has a captain and an expert that will help the 'ordinary' competitors to achieve their objectives. The captain is the best worker in the team and he/she will stay with the team until they lose or become champions while the expert only works with the team one episode.