WASHINGTON (Reuters) - A Senate panel urged the Air Force on Thursday to start developing an export model of its F-22 Raptor, the most advanced U.S. fighter jet, even as it voted to end U.S. purchases. Japan, Israel and Australia have shown interest in buying the supersonic, radar-evading F-22 Raptor, designed to destroy enemy air defenses in the first days of any conflict and clear the way for other missions.