Researchers at the U.S. Naval Research Laboratory flew their
fuel cell powered Ion Tiger UAV for 48 hours and 1 minute on April 16-18 by
using liquid hydrogen fuel in a new, NRL-developed, cryogenic fuel storage tank
and delivery system. This flight shatters their previous record of 26 hours and
2 minutes set in 2009 using the same vehicle, but with gaseous hydrogen stored
at 5000 psi.
Liquid hydrogen is three times denser than 5000-psi
compressed hydrogen.