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A comment on LightSail 2 Spacecraft Successfully Demonstrates Flight by Light. Parent comment

Re:LightSail 2 Spacecraft Successfully Demonstrates Flight b... by redorb on Wednesday July 31, 2019 @06:16PM (#20579111)
mythbusters were able to show a weird effect where the fan on a boat thing worked - I think they chalked it up to some blown wind from the fan drawing in more than from around the fan..

https://youtu.be/uKXMTzMQWjo?t=75

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Re:LightSail 2 Spacecraft Successfully Demonstrates Flight b... by walrus01 on Wednesday July 31, 2019 @07:01PM (#20579488)
From a physics point of view it's not like they created an infinite motion machine, the stored energy in the liquid petroleum is being burned, heat from the internal combustion engine radiated into the atmosphere, etc.

It's just converting stored energy (some amount of kJ or kWh in a fuel tank, or battery) into an aerodynamically weird highly inefficient thrust method.

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