[b]PH:

The engine can be installed with the cylinder at any angle you wish. Simple planes usually have the cylinder on top, as that's generally the easiest to set up and have good performance. But it does detract from the looks of most semi scale and scale planes.

The next most common, and often chosen for models of planes with horizontally opposed engines such as your Cessna model, is with the cylinder to the plane's right side. This gets the engine out of sight from all views but the right side, and points the exhaust to a lower point helping keep the plane clean. And with the engine on its side, set up isn't any different from upright.

Another option is angling the cylinder downward to center the muffler under the plane. In some cases this will also conceal the engine without having to go fully inverted.

Finally, the inverted mounting is almost necessary on a plane like a Mustang or Spitfire, since that is the only way even to have the engine more than partially concealed. Setting an inverted engine for running is the hardest to learn, not recommended for a relatively inexperienced flier.

Bill.