5 ms·

Then do electric aircraft. We can do 500-1000 mile electric air travel. Longer term, >3000 mile. Plus multiple hops. Still faster and cheaper than rail.

sokoloff 5y ago
> We can do 500-1000 mile electric air travel. We can? Present tense, certified, operational aircraft in service? Or do you mean that people are working on building them now and hope to have them in service at some point in the future?
- Robotbeat 5y ago
  The latter. I think we can have them in service before we could complete a new HSR line starting from scratch, at least in the US. (I think Europe is better at this kind of HSR infrastructure, so maybe it wouldn't be as bad.)
RC_ITR 5y ago
We 100% cannot do those things with current technology. I'm 'commenting too fast' to reply, but show me any of your examples in flight please.
- Robotbeat 5y ago
  We absolutely can. https://twitter.com/GovInslee/status/1440442441920774146 https://twitter.com/GovInslee/status/1440442441920774146 500+ miles range. Building it right now. Plus Wright Electric, Bye Aerospace’s eflyer 800, etc. Why do people so easily and confidently claim something can’t be done?
  - burkaman 5y ago
    That carries 9 passengers, at ~half the speed of a standard airliner. It's exciting and I want to fly in one, but I don't think it will be faster and cheaper than trains in most cases, yet. But we're almost there.
    - Robotbeat 5y ago
      The technology is independent of scale. If it works for a nine Seater it also works for a 100 Seater. EDIT: and YES this is true. Battery specific energy is 200-400Wh/kg. That is PER kilogram. And larger planes are NOT less efficient per passenger than smaller ones. Small and large jets or propeller aircraft have a out the same life to drag ratio. If anything, larger tend to be better due to Reynolds Number effects. There is maybe not one misconception about electric flight that I’ve seen repeated most often by Internet skeptics than this false idea that “bigger is disproportionately harder for electric planes.” It is simply. Not. True.
      - burkaman 5y ago
        That's not true unfortunately, batteries are too heavy to make bigger planes workable right now. We need denser batteries and more powerful electric motors, and there are companies working on both those problems, but they aren't solved yet. Look at the specific energy of jet fuel compared to batteries on this page: https://en.wikipedia.org/wiki/Energy_density https://en.wikipedia.org/wiki/Energy_density
        Robotbeat 5y ago
        Specific energy is independent of scale! It’s right in the units: energy divided by mass. Watt-hours per kg. Where are you getting the claim from that larger planes can’t technically be made electric even if smaller ones can? And no, don’t switch topic to range. That is a known constraint. Focus on SCALE. It is scale-independent to zeroth and first order at least! This comes up every single time, and I feel like I’m taking crazy pills. :D
        burkaman 5y ago
        I mean I'm not really qualified to have this debate, but I'll do my best. Intuitively, if you double the weight of the plane, now you need twice as much battery to fly it. But now you've added a bunch of battery weight, so you need even more batteries to lift those batteries. You also will need more or bigger motors, which adds even more weight. At some point, your plane isn't gonna get off the ground. I am only a lowly software engineer so I don't know that much about planes or batteries. If I'm wrong then I'm wrong, and I hope I am.
  - Nitrolo 5y ago
    Not to diminish the accomplishments shown there, but that plane seats maybe a dozen people? Most airliners can seat 100+, and their range is sometimes an order of magnitude higher than that. The problem is that batteries are significantly less energy dense than jet fuel, both by weight and by volume. To reach capacities and ranges of modern airliners you'd need batteries that are much more dense, compact, and light, and afaik there's nothing even close to the improvements needed right now.
    - Robotbeat 5y ago
      Wrong about capacity but correct about range. I have no idea why people keep thinking that batteries would work worse for 100 seats rather than nine seats. The technology is independent of scale except in the trivial sense that you need proportionally more battery and cost since you’re 10 times larger. True the range is less, but we have built jets that can go 40,000km. We don’t need that much range to do short flights, comparable in length to the California HSR project. Existing battery technology is more than sufficient for that.
- golemiprague 5y ago
  I agree regarding battery based aircraft, but what about hydrogen?
yongjik 5y ago
That's... not really an argument? Electric aircraft are not economically viable until we account for externalities, so we're moving in the right direction. Even after carbon tax, electric aircraft is still a technology in its infancy, compared to electric trains. Are you proposing that the government should spend billions of $$$ on an experimental technology when a proven alternative exists?

sokoloff 5y ago

> We can do 500-1000 mile electric air travel. We can? Present tense, certified, operational aircraft in service? Or do you mean that people are working on building them now and hope to have them in service at some point in the future?

Robotbeat 5y ago
The latter. I think we can have them in service before we could complete a new HSR line starting from scratch, at least in the US. (I think Europe is better at this kind of HSR infrastructure, so maybe it wouldn't be as bad.)

RC_ITR 5y ago

We 100% cannot do those things with current technology. I'm 'commenting too fast' to reply, but show me any of your examples in flight please.

Robotbeat 5y ago
We absolutely can. https://twitter.com/GovInslee/status/1440442441920774146 https://twitter.com/GovInslee/status/1440442441920774146 500+ miles range. Building it right now. Plus Wright Electric, Bye Aerospace’s eflyer 800, etc. Why do people so easily and confidently claim something can’t be done?
- burkaman 5y ago
  That carries 9 passengers, at ~half the speed of a standard airliner. It's exciting and I want to fly in one, but I don't think it will be faster and cheaper than trains in most cases, yet. But we're almost there.
  - Robotbeat 5y ago
    The technology is independent of scale. If it works for a nine Seater it also works for a 100 Seater. EDIT: and YES this is true. Battery specific energy is 200-400Wh/kg. That is PER kilogram. And larger planes are NOT less efficient per passenger than smaller ones. Small and large jets or propeller aircraft have a out the same life to drag ratio. If anything, larger tend to be better due to Reynolds Number effects. There is maybe not one misconception about electric flight that I’ve seen repeated most often by Internet skeptics than this false idea that “bigger is disproportionately harder for electric planes.” It is simply. Not. True.
    - burkaman 5y ago
      That's not true unfortunately, batteries are too heavy to make bigger planes workable right now. We need denser batteries and more powerful electric motors, and there are companies working on both those problems, but they aren't solved yet. Look at the specific energy of jet fuel compared to batteries on this page: https://en.wikipedia.org/wiki/Energy_density https://en.wikipedia.org/wiki/Energy_density
      - Robotbeat 5y ago
        Specific energy is independent of scale! It’s right in the units: energy divided by mass. Watt-hours per kg. Where are you getting the claim from that larger planes can’t technically be made electric even if smaller ones can? And no, don’t switch topic to range. That is a known constraint. Focus on SCALE. It is scale-independent to zeroth and first order at least! This comes up every single time, and I feel like I’m taking crazy pills. :D
        burkaman 5y ago
        I mean I'm not really qualified to have this debate, but I'll do my best. Intuitively, if you double the weight of the plane, now you need twice as much battery to fly it. But now you've added a bunch of battery weight, so you need even more batteries to lift those batteries. You also will need more or bigger motors, which adds even more weight. At some point, your plane isn't gonna get off the ground. I am only a lowly software engineer so I don't know that much about planes or batteries. If I'm wrong then I'm wrong, and I hope I am.
- Nitrolo 5y ago
  Not to diminish the accomplishments shown there, but that plane seats maybe a dozen people? Most airliners can seat 100+, and their range is sometimes an order of magnitude higher than that. The problem is that batteries are significantly less energy dense than jet fuel, both by weight and by volume. To reach capacities and ranges of modern airliners you'd need batteries that are much more dense, compact, and light, and afaik there's nothing even close to the improvements needed right now.
  - Robotbeat 5y ago
    Wrong about capacity but correct about range. I have no idea why people keep thinking that batteries would work worse for 100 seats rather than nine seats. The technology is independent of scale except in the trivial sense that you need proportionally more battery and cost since you’re 10 times larger. True the range is less, but we have built jets that can go 40,000km. We don’t need that much range to do short flights, comparable in length to the California HSR project. Existing battery technology is more than sufficient for that.
golemiprague 5y ago
I agree regarding battery based aircraft, but what about hydrogen?

yongjik 5y ago

That's... not really an argument? Electric aircraft are not economically viable until we account for externalities, so we're moving in the right direction. Even after carbon tax, electric aircraft is still a technology in its infancy, compared to electric trains. Are you proposing that the government should spend billions of $$$ on an experimental technology when a proven alternative exists?