sentences:  In 1931 more powerful engines replaced those used in the endurance flight and it was re-designated as a C-7 transport.The aircraft was damaged beyond economical repair in 1932 when it crash-landed in Texas after running out of fuel and was scrapped.The flight demonstrated the military application of the concept, but while it inspired numerous efforts to set even greater endurance records, development of a practical in-flight refueling system was largely ignored by the world's air forces before World War II.