A controlled expansion stent graft delivery system has an adjustment configuration in which a retractable sheath is at a retracted position out of contact with a stent graft, but expansion of the stent graft is controlled by a control tether, which has a middle segment wrapped around a fabric tube of the stent graft. The stent graft changes diameter responsive to a tension level in the control tether. At least one of an orientation and a position of the stent graft may be adjusted during controlled expansion via the control tether. After proper placement of the stent graft, a tip clamp assembly can be actuated to unclamp and release the control tether.