Robert,
As Jamo pointed out, there's an exhaust port at the end of each cylinder head, and that's how it is for ALL rotaries. What many people mistakenly confuse as exhaust pipes on these engines are actually air induction pipes for the engine. (Also, many people also confuse the two intake pipes on either side of a Fokker Triplane or Nieuport as exhausts, when they are the induction pipes as well.)
Warren