A device to assemble a skin and a frame of an aircraft fuselage. The device includes first and second brace members that extend along opposing sides of a gap. Arches are spaced apart and fixedly connected to the first and second brace members and that extend across the gap. A strongback is attached to and movable along the first and second brace members with the strongback having a curved shape that matches the plurality of arches. The strongback includes clamps configured to engage with the frame. First and second tension devices apply tension to the skin at the strongback.