The TACIT BLUE (Whale) aircraft was built to test the advances in stealth technology. The U.S. Air Force, the Defense Advanced Research Projects Agency (DARPA), and the Northrop Corporation worked together from 1978 to 1985 to demonstrate that curved surfaces on an aircraft result in a low radar return signal from ground radar. With such a low radar return signal, TACIT BLUE demonstrated that such an aircraft could operate safely close to the battlefield forward line without fear of being discovered by enemy radar. It could continuously monitor enemy forces behind the battlefield and provide targeting information to a ground command center.