Originally Posted by
lomapaseo
I don't follow the premise of the OP?
Does the counter-rotation involve any compressors or just the fan/turbine?
What is the by-pass ratio for this?
"According to Snecma, such architecture enables the bypass ratio to be increased significantly, allowing the concept to meet, in combination with material and installation improvements, the goal set for the European Union’s VITAL project of an 18% reduction in fuel burn over current-generation engines."
IATA Technology Roadmap (P44)
There's also a link (dead) to a Flight article about it in the 24th April 2007 issue, if anyone has it to hand.