CRASH VICTIMS IDENTIFIED •'LAS VEGAS, Nev., 'May 12 (P) •j—Las Vegas Air Force base-today identified two a'ir force, men .'killed yesterday ' when- their- F-82 fighter plane crashed in the Indian-Springs rocket fifing 'area. They are* Lt. Ralph-H. Tibbetts, 27, attached to Bergstrom Air base, Austin, and Staff Sgt. Kenneth Austin, Lockbourne Air. base, Columbus, .-Ohio. Their -.home towns were not known. ..