An article of manufacture includes a first rotor having a first flow-through area that is more than 50% of a total first rotor flow area and a first ridged arc member, and a second rotor having a second flow-through area that is more than 50% of a total second rotor flow area and a second ridged arc member. The article further includes an upstream stator and a downstream stator, each stator having a co-extensive stator flow-through area and a co-extensive structural area. The article includes an actuator having an engagement gear between the ridged arc members, where a turn of the engagement gear moves the ridged arc members in opposing directions. The first rotor and second rotor are phased to be at a maximum closed at a first position of the engagement gear and a maximum open at a second position of the engagement gear.