Originally Posted by
JamesNoBrakes
And I'd think the secondary problem would be IF you could have adequate battery density, it would seem it'd be better to just use an electric motor to drive a fan, like pretty much every other electric airplane proposal. Using this exotic process to generate a "jet" of air that would still need to turn a fan, seems to add a lot of extra steps that would just waste energy and add weight. Making plasma is not a big deal, you can do it between electrical contacts. Making it on the scale that would actually transfer enough heat to the air and sustaining that would take massive amounts of energy. I would think this is more along the lines of "we found a new/novel way to make plasma", but due to the laws of thermodynamics and physics, it takes a massive amount of energy to create. Otherwise, as said in this thread, they are essentially claiming "free energy".
Plasma is good for spacecraft, because you have to bring your own reaction mass and it can be accelerated to very high velocities . The more energetic that mass is when it parts company with you, the better your delta-v. And 1/2MV^2 says that a little additional velocity goes a long way, and a lot of additional velocity goes a very, very long way. For a given amount of working mass.
But if you have all the free air you can use, yeah it seems like a fan would be a lot simpler.