Colin DemarestCrew chiefs prepare an ULTRA aircraft for taxiing. Photo: Kregg York/DVIDSA secretive drone designed to reap intelligence from faraway targets flew for at least three days straight in recent testing, a feat its maker shared first with Axios.Why it matters: The marathon flight — possibly twice as long as other drones' — could shake up how the U.S. military approaches overhead surveillance, for which there is an insatiable appetite.Zoom in: The Dzyne-made Unmanned Long-endurance Tact...