LGN Hi,
The only Contra prop system I can think about was the Shackleton (piston x 4 egines)and the Bear(turboprop x 4 turbo), whilst I follow your reasoning for critical engine and yaw, are you referring to yaw caused by lack of power input or yaw caused by dead engine props not feathered, therfore causing huge drag on the relevent wing?
[ 10 August 2001: Message edited by: Vfrpilotpb ]