http://www.break.com/index/jet-powered-merry-go-round.html
I was just reading about this the other day in PM actually. That was the maiden voyage, one of them is the PM Editor. And then the fire department showed up.
Apparently, it is a ramjet that is shaped like a tuning fork. Once it is primed with a leafblower (as shown) the explosions are pretty much self-sustained as you add fuel. That's the pulsing sound that you hear.
