As several responses have mentioned, there were other "hollow logs" than the ones designed by Walt Musciano and kitted by Scientific. If you are building one for competition in the Musciano contests it MUST be one of Walts Scientific designs.

I think all of the Musciano contests follow the rules created by the Northern Virginia Control Line (NVCL) club. Their web site has the rules for the events, a list of eligible designs, and a list of eligible engines.

They also have some great pictures of the event.

George

Edit: Here's the link... http://www.northernvirginiacontrolline.org/