yes they were the J79 engines in afterburner extra loud,,,when we were testing the engine ,we use to throw a qt of oil into the fire stream behind the engine,,, big blue smoke when it would explode ,,, and when it went into afterbuner the ground shook,, and the next day we had to go through all the nuts bolts brackets to make sure none were cracked or loose. the C5 was kinda loud also jim