Assertion: hovercraft's propeller | /r/HasProperty | studied for use
Facets:
value: since the 1940s
type: TEMPORAL
value: to delay the onset of shockwaves
type: PURPOSE
value: in high-speed applications
type: LOCATION
Source sentences:
text: Since the 1940s, propellers and propfans with swept tips or curved "scimitar-shaped" blades have been studied for use in high-speed applications so as to delay the onset of shockwaves, in similar manner to wing sweepback, where the blade tips approach the speed of sound.