5 ms·

So according to their stated information it consumes about 6L of gasoline per passenger per 100km. Which is: - much higher than a car - much lower than a pow

So according to their stated information it consumes about 6L of gasoline per passenger per 100km. Which is: - much higher than a car - much lower than a power-boat - about 25% lower than a Cessna Caravan (which is faster tho).

cassepipe 3y ago
I was surprised to learn that in a Plane it was around half that : https://en.wikipedia.org/wiki/Fuel_economy_in_aircraft#Airlines https://en.wikipedia.org/wiki/Fuel_economy_in_aircraft#Airli... Then I remember that it was kerosene but it seems that kerosene has a close energy density to gasoline... I am lost. Can someone help ?
- goodcanadian 3y ago
  Air resistance. Commercial aircraft fly as high as they reasonably can in order to reduce the amount of atmosphere they have to push through. The ground effect craft operates at sea level.
- HPsquared 3y ago
  See also why suborbital rockets could actually be competitive for passenger travel over very long distances: no air resistance in space.
- deleted 3y ago
  [deleted]
- t0mas88 3y ago
  It's very small so the per seat usage is higher than a high density airliner. The comparison to a Cessna Caravan makes some sense, that's similar sized turbine powered.
- usrusr 3y ago
  The environmental issue with air travel is not high fuel consumption per passenger mile, but the number of miles per passenger. A coast to coast trip by car might burn just as much fuel as coast to coast by plane, but people simply wouldn't to that all that often in a lifetime. That's for medium and long distance travel, short distance fuel consumption per passenger mile goes up dramatically. OT: this is actually a point where I see a big, unserved gap in the market of climate-aware air travel. A feeder plane (from regional to intercontinental airport) dedicated to the market segment of "going by road or train might be roughly as fast, but I need to go to the airport and I can't risk missing my connection due to the unpredictable nature of ground travel". So you'd want a something the size of a CRJ or even just a dash-8, but ruthlessly optimized for fuel consumption. That would imply going slower (no issue at all when the time for bording etc greatly outweighs the time spent in the air!) which would imply moving the deep point in that induced vs parasitic drag diagram as far left as possible, which would imply going wild with wingspan, something sleek, carbon, like a performance glider, as wide as a 737 or beyond. One reason I've heard suggested for why this doesn't yet exist is that on those short hops (little time spent in the air), fuel cost is actually outweighed by crew cost so much that all the cost saving from lower fuel consumption would be eaten by getting less trips per crew-day. So it's an automaton problem in disguise? Or a regulatory problem?
  - notahacker 3y ago
    For that sort of range hydrogen electric is also starting to look viable
    - usrusr 3y ago
      Hydrogen electric is little more than greenwashing before we have anything resembling a hydrogen surplus on the horizon. Energy density is always an issue in flying applications and it's well possible that a boring old turboprop burning efuels (made from that very same hydrogen surplus) would be the clear winner. Losses of the transformation pipeline vs losses from carrying the most impractical fuel type ever tried. Minimizing the energy requirement at the final conversion step is an important thing all too often missed in the frenzy of converting the path to get there.
  - Swenrekcah 3y ago
    I want the world to move to a system of very large and spacious and cool aircraft for major hub-to-hub travel, and then nice and comfortable high speed rail from hub to destination. I’m tired of cramming into a narrowbody with no service. Let me fly on an engineering marvel like the A380 or 747 and then relax or work in a comfortable train seat.
    - aghastnj 3y ago
      We've got that, already. They're called "trains." We just need to make them faster.
    - ramses0 3y ago
      The real answer is "wings clipped to tubes". Load the cheap tube at your leisure, drag it by semi under the waiting "wing". Clip, clip, vroom... There was a great concept video of a train/bus station that did something similar, divorcing the loading of people into the tube from the attaching the tube to the train. It allowed the train to keep going nearly 100% full speed, "magically" grabbing the tube loaded with passengers, and letting them pass into the moving portion (below) without stopping the train. The passenger pickup capsule was then dropped off at the next station for the process to repeat. See dead links here: https://www.smithsonianmag.com/innovation/this-high-speed-train-picks-up-passengers-without-having-to-stop-180948281/ https://www.smithsonianmag.com/innovation/this-high-speed-tr... Saves kinetic energy (no stopping and starting), and time because you're not incurring +5min per each stop/station.

cassepipe 3y ago

I was surprised to learn that in a Plane it was around half that : https://en.wikipedia.org/wiki/Fuel_economy_in_aircraft#Airlines https://en.wikipedia.org/wiki/Fuel_economy_in_aircraft#Airli... Then I remember that it was kerosene but it seems that kerosene has a close energy density to gasoline... I am lost. Can someone help ?

goodcanadian 3y ago
Air resistance. Commercial aircraft fly as high as they reasonably can in order to reduce the amount of atmosphere they have to push through. The ground effect craft operates at sea level.
HPsquared 3y ago
See also why suborbital rockets could actually be competitive for passenger travel over very long distances: no air resistance in space.
deleted 3y ago
[deleted]
t0mas88 3y ago
It's very small so the per seat usage is higher than a high density airliner. The comparison to a Cessna Caravan makes some sense, that's similar sized turbine powered.
usrusr 3y ago
The environmental issue with air travel is not high fuel consumption per passenger mile, but the number of miles per passenger. A coast to coast trip by car might burn just as much fuel as coast to coast by plane, but people simply wouldn't to that all that often in a lifetime. That's for medium and long distance travel, short distance fuel consumption per passenger mile goes up dramatically. OT: this is actually a point where I see a big, unserved gap in the market of climate-aware air travel. A feeder plane (from regional to intercontinental airport) dedicated to the market segment of "going by road or train might be roughly as fast, but I need to go to the airport and I can't risk missing my connection due to the unpredictable nature of ground travel". So you'd want a something the size of a CRJ or even just a dash-8, but ruthlessly optimized for fuel consumption. That would imply going slower (no issue at all when the time for bording etc greatly outweighs the time spent in the air!) which would imply moving the deep point in that induced vs parasitic drag diagram as far left as possible, which would imply going wild with wingspan, something sleek, carbon, like a performance glider, as wide as a 737 or beyond. One reason I've heard suggested for why this doesn't yet exist is that on those short hops (little time spent in the air), fuel cost is actually outweighed by crew cost so much that all the cost saving from lower fuel consumption would be eaten by getting less trips per crew-day. So it's an automaton problem in disguise? Or a regulatory problem?
- notahacker 3y ago
  For that sort of range hydrogen electric is also starting to look viable
  - usrusr 3y ago
    Hydrogen electric is little more than greenwashing before we have anything resembling a hydrogen surplus on the horizon. Energy density is always an issue in flying applications and it's well possible that a boring old turboprop burning efuels (made from that very same hydrogen surplus) would be the clear winner. Losses of the transformation pipeline vs losses from carrying the most impractical fuel type ever tried. Minimizing the energy requirement at the final conversion step is an important thing all too often missed in the frenzy of converting the path to get there.
- Swenrekcah 3y ago
  I want the world to move to a system of very large and spacious and cool aircraft for major hub-to-hub travel, and then nice and comfortable high speed rail from hub to destination. I’m tired of cramming into a narrowbody with no service. Let me fly on an engineering marvel like the A380 or 747 and then relax or work in a comfortable train seat.
  - aghastnj 3y ago
    We've got that, already. They're called "trains." We just need to make them faster.
  - ramses0 3y ago
    The real answer is "wings clipped to tubes". Load the cheap tube at your leisure, drag it by semi under the waiting "wing". Clip, clip, vroom... There was a great concept video of a train/bus station that did something similar, divorcing the loading of people into the tube from the attaching the tube to the train. It allowed the train to keep going nearly 100% full speed, "magically" grabbing the tube loaded with passengers, and letting them pass into the moving portion (below) without stopping the train. The passenger pickup capsule was then dropped off at the next station for the process to repeat. See dead links here: https://www.smithsonianmag.com/innovation/this-high-speed-train-picks-up-passengers-without-having-to-stop-180948281/ https://www.smithsonianmag.com/innovation/this-high-speed-tr... Saves kinetic energy (no stopping and starting), and time because you're not incurring +5min per each stop/station.