Assertion: hovercraft's inventor | /r/CapableOf | try to build vehicle
Facets:
value: for 50 years
type: TEMPORAL
Source sentences:
text: Cockerell was not the first man to think of the idea; for 50 years inventors had tried to build vehicles capable of riding on air, but they had always hit technical snags, partly because they had not been able to devise an effective means of holding the air cushion in place.