On Tue, 05 Jun 2007 21:11:46 GMT, Ron Hardin
wrote:

Of course, the exhaust blowing out the front turns the turbine backwards,
and the exhaust blowing out the back turns it forwards. You're where you
started, in explaining it.

If this is a serious question, it may have something to do with the
fact that more of the energy produced by burning the fuel is used
driving the compressor than is used for propulsion.

TC