Boeing intended to use advanced composite and titanium materials to reduce weight and further improve fuel efficiency.[1] In order to successfully build a commercial airplane with such a high advanced materials content (projected to be 60-70% of the airframe by weight), Boeing lined up a consortium of international partners with experience in aerostructures.[2] By the end of 2001, those materials were being applied to an aircraft in Project Yellowstone, a competing project using more conventional airplane designs.[4] That aircraft, being designed under Yellowstone as the replacement for the 757/767, was later announced as the 7E7, with "E" standing for "Efficient".[20][21] As a baseline reference model using advanced materials, the proposed 7E7 would consume 10% less fuel than the Sonic Cruiser, and 17-20% less than the 767-300.[7]