Gas turbine engine outlet guide vane assembly

A single unducted rotor engine defining an axial direction, and a radial direction, and a circumferential direction, the engine comprising:

• a power source;
• a casing surrounding the power source;
• an unducted rotor assembly driven by the power source comprising a single row of rotor blades;
• and
• an outlet guide vane assembly comprising a plurality of pairs of outlet guide vanes,
• wherein each pair of the plurality of pairs of outlet guide vanes includes a first outlet guide vane extending from the casing at a location downstream from the single row of rotor blades of the unducted rotor assembly and a second outlet guide vane also positioned downstream from the single row of rotor blades of the unducted rotor assembly,
• wherein the first outlet guide vane of each pair of outlet guide vanes defines a first geometry span,
• wherein the second outlet guide vane of each pair of outlet guide vanes defines a second span,
• wherein the first span is not equal to the second span,
• wherein the first and second outlet guide vanes of each pair of outlet guide vanes are each variable pitch outlet guide vanes,
• wherein the engine further comprises, for each pair of outlet guide vanes, a pitch change plate configured to rotate about an axis extending substantially perpendicular to a centerline axis of the engine on which the first outlet guide vane and the second outlet guide vane are mounted such that, for a predetermined pitch position of the pitch change plate, leading edges of the first outlet guide vane and the second outlet guide vane are substantially aligned along the circumferential direction.