https://patents.google.com/patent/US10144532B2/en
This was in one of the replies but I am not a physics major or anything so I couldn’t understand anything. Wanted to know what this was for fun.
In: 2
Its an EM drive. The idea behind it is that if you pump a bunch of microwaves into it, they’ll be reflected around inside of the chamber until they escape. More will end up escaping from the large side than the small one, so you get a net force towards the small side. Its essentially an attempt to create an analogue of a solar sail that uses a small, attached microwave emitter as a substitute for the sun.
NASA has built a few of them and in 2016 found a very small net thrust in the direction of the small side. The timing of that experiment lines up with when the patent was filed. The fact that the Navy filed it, rather than NASA, is indicative of the fact that it was actually the military – and not NASA – that was funding that experiment.
There have been a few more experiments since that have found a slight net thrust. In all of the experiments, the amount of thrust found was extremely, extremely small. Right now the consensus is that the apparent thrust being generated isn’t actually thrust, but rather is due to the effect of heat on the shape of the cylinder. The cylinder gets really hot while the microwave is running. Due to its shape, when it gets hot, some of the weight of the cylinder shifts towards its small end, which will result in a very slight reading on the equipment that is being used to measure net thrust.
IE, the current consensus is that it doesn’t actually work and it doesn’t appear as though either NASA or the Navy is funding ongoing experiments into it anymore.
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