4 ms·

I'm sure most people would rather see a critique of the science behind Ion Propulsion than a rant about the content of this youtube channel.

theothermkn 8y ago
The critique of the propulsion scheme was laid out in the video. It was just framed in a way that tried to dodge the reality that this system cannot scale. For example, rather than presenting the thrust densities in a table for easy comparison, they were presented serially, so that the viewer might miss their relative scales. Quickly: What is the ratio of the thrust density of a jet engine to the thrust density of this ion propulsion scheme?[1] Near the end, during the segue to the sponsorship at the end, he says, "This technology is in its infancy," alluding to his opening comparison to the Wright brothers. This is ridiculous. Not all weak or underpowered novel things are "in their infancy," awaiting further development into enabling technologies for our Glorious Future. This one, for example, has all the problems of battery energy density plus the problems of dragging, for example, tens of kilometers of wires through the atmosphere at passenger-jet speeds. But, as I said at the beginning, that critique is contained in the video, just framed positively and obscured by weasel tactics. [2] [1] Roughly 3300 to 1. An airliner using this scheme would need engines with a frontal area equal to 6600 high-bypass turbofan engines. [2] Brought to you by Carl's Jr.
- frankmcsherry 8y ago
  I just watched this, and it was abundantly clear that the presenter believes there is a scaling issue ("scaling these propulsion methods is not easy" at 6:37). They literally say this, and then present the 10,000N/m^2 vs 3N/m^2 numbers for the jet engine versus this engine. There is then a minute or so explaining why this is a problem.

4 ms·

I'm sure most people would rather see a critique of the science behind Ion Propulsion than a rant about the content of this youtube channel.

by imustbeevil 8y ago

theothermkn 8y ago
The critique of the propulsion scheme was laid out in the video. It was just framed in a way that tried to dodge the reality that this system cannot scale. For example, rather than presenting the thrust densities in a table for easy comparison, they were presented serially, so that the viewer might miss their relative scales. Quickly: What is the ratio of the thrust density of a jet engine to the thrust density of this ion propulsion scheme?[1] Near the end, during the segue to the sponsorship at the end, he says, "This technology is in its infancy," alluding to his opening comparison to the Wright brothers. This is ridiculous. Not all weak or underpowered novel things are "in their infancy," awaiting further development into enabling technologies for our Glorious Future. This one, for example, has all the problems of battery energy density plus the problems of dragging, for example, tens of kilometers of wires through the atmosphere at passenger-jet speeds. But, as I said at the beginning, that critique is contained in the video, just framed positively and obscured by weasel tactics. [2] [1] Roughly 3300 to 1. An airliner using this scheme would need engines with a frontal area equal to 6600 high-bypass turbofan engines. [2] Brought to you by Carl's Jr.
- frankmcsherry 8y ago
  I just watched this, and it was abundantly clear that the presenter believes there is a scaling issue ("scaling these propulsion methods is not easy" at 6:37). They literally say this, and then present the 10,000N/m^2 vs 3N/m^2 numbers for the jet engine versus this engine. There is then a minute or so explaining why this is a problem.