| http://www.w3.org/ns/prov#value | - Aug. 14, 1945 describing a swivelling screw propeller, and U.S. Pat. No. 508,324 issued to Leisen Nov. 7, 1893 illustrating a screw type propeller, plus other devices describing such solutions as jet propulsion, nuclear energy driven systems, and the like, but all of these are generally impractical for various reasons, particularly due to their complexity and high manufacturing costs, whereas noth
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