Storm chaser
The boy's father, Richard Heene, is an amateur scientist, according to a 2007 Denver Post article on weather chasers. He joined another man, Scott Stevens, to form a Fort Collins-based weather-research team they called The Psyience Detectives.
Police say there are pegs on the bottom of the aircraft that indicate that a box was attached at some point.
This is confusing - first they say he was in the batter compartment, shown on your diagram, and then they reference an attached box.
http://www.9news.com/news/article.aspx?storyid=125161&catid=339