HARTFORD, CT -- The Air Force is in the final stages of negotiations with engine-makers Pratt & Whitney and General Electric for a prototype program meant to mature advanced technologies that could be used to field higher-performing and more fuel-efficient engines and upgrades for key Air Force platforms. The companies have been developing and maturing technologies through the service's Advanced Engine Technology Demonstration program since 2011 and are on pace to conduct hardware demonstrations early next year. At the same...