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> A Cirrus SR22 can go 1,200 miles on 80 gallons of gas. That's roughly speaking 15 miles per gallon - better than many pickup trucks or large SUVs. Sure, let'

> A Cirrus SR22 can go 1,200 miles on 80 gallons of gas. That's roughly speaking 15 miles per gallon - better than many pickup trucks or large SUVs. Sure, let's take the most energy efficient aircraft and compare it to the least energy efficient passenger vehicles??? I mean, how can one even pretend that is a fair comparison. More generally for energy efficiency, it is well known that the most efficient trip is a shorter one or one never taken. Many fans of these technologies are people who dream of living 90 miles away and fly into town in half an hour. Or as you described "this would replace a two hour trip across a city in traffic with a fifteen minute flight". Comparing MPG when your technology is designed to encourage more miles is a flawed approach.

kayfox 9y ago
I think lowering the time cost of coming into the office would lead to more telecommuting than less. Since you can get into the office in 15 minutes, you don't have to go to the office every day just in case you need to have an impromptu meeting.
danielvf 9y ago
We do seem to have different value systems. I believe applying energy to make human lives better is a great thing! Electricity usage in the western world is getting greener fast. Total usage is going down, not up. This isn't going to reverse either of those trends. There's a popular perception that all aircraft burn energy like an oil refinery on fire. The reality is that small piston aircraft are approximately as fuel efficient as the vehicles around you on the highway (at least where I live) while getting you there a whole lot faster. A Cirrus is a good comparison stand in for the KittyHawk aircraft because it has a similar design and construction style (ignoring the dodeca-props), four seats, and is the most common general aviation aircraft not designed in the 1950's. A Cirrus isn't even close to the most energy efficient aircraft - that would be more like 60 mpg, nor is it the most efficient in its class.
- deleted 9y ago
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- dzhiurgis 9y ago
  > Electricity usage in the western world is getting greener fast. 81% of energy produced in NZ is renewable. Complex terrain would make such vehicle a saviour. Plus, in any terrain planes almost always travel less, so savings are intrinsic. Finally, using "taxi" name here is awful. At the most it's going to be an entertainment device initially (tourism and extremely expensive attractions are insane in NZ), method of access remote places later.
- pc86 9y ago
  > The reality is that small piston aircraft are approximately as fuel efficient as the vehicles around you on the highway This is just objectively wrong. Before taking wind into account, a Cessna 172 travels 120kts on a good day and at altitude and appropriately leaned can get down to 8 gallons an hour. 120 nautical miles in 140 miles (less, but benefit of the doubt and all). That's 17.5 miles per gallon. At cruise altitude. Leaned appropriately. You can tack on another few gallons for the climb, and you're going mixture rich on descent so you're back up to 10-11 gph for the last 20-30 miles of your trip. You're lucky to get 10mpg overall for a flight, and that's using gas that costs $5 a gallon. There are a LOT of benefits to GA flight in order to get around. Fuel efficiency is definitely not one of them.
  - sixbrx 9y ago
    Well for the autos you need to consider that they may commonly be in rush hour traffic, too, stopped and idling quite a bit.
    - pc86 9y ago
      It's a good thing the EPA has highway fuel economy ratings then so we can compare apples to apples.
  - DennisP 9y ago
    He specified "general aviation aircraft not designed in the 1950's." The Cessna 172 was first flown in 1955: https://en.wikipedia.org/wiki/Cessna_172 https://en.wikipedia.org/wiki/Cessna_172 Also, it may be worth taking into account that airplanes travel in straighter lines.
    - pc86 9y ago
      I'm talking about overall miles traveled so I'm not sure the straight line thing matters. Yes for the same trip you will travel a shorter distance in a plane. The plane will also be running for 20-30 minutes prior to takeoff and 5-10 minutes after landing. If you exclude GA aircraft not designed in the mid-20th century, you exclude 90% of GA aircraft and 99% of certified GA aircraft. We can make that distinction if you want but it ignores reality.
- tripzilch 9y ago
  > We do seem to have different value systems. I believe applying energy to make human lives better is a great thing! Your conclusion that we must have different value systems only shows where you stopped thinking. We differ in the timescale on which we consider the betterment of human lives. And we differ in the subset of human lives we consider the betterment of. If you remain convinced we have different value systems, then it's not about energy or the betterment of human lives (or straw lives), but about placing a low value on short-sightedness and egotism.
Kalium 9y ago
You're absolutely right. We should be encouraging density to save energy and be ecologically friendly. What's most wonderful is that we don't even need any new technologies to do it! It may be possible that this is something of a politically difficult problem in many areas, though. Until San Francisco actually allows itself to become a real city, we may be stuck looking at workarounds. It's very, very, very far from ideal. Exactly as you say. But it may be the best we can do for now.
deleted 9y ago
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rukittenme 9y ago
The most efficient trip is the one not taken but what do we lose by not taking it? Is that cross town trip trivial, necessary, or serve a higher purpose? I don't think anyone would stop a human-rights march because of energy efficiency concerns. And who cares about energy efficiency when the energy is clean? It's well-known that the US is trending greener and this electric taxi is years away from widespread adoption.
marze 9y ago
Solar electricity will be nearly free shortly, so efficiency isn't an important issue. Cost still is of course. Solar is becoming so cheap that an excessive amount of generation will be installed, so adequate generation will be available in morning or evening, or with clouds. During peak sun, excess power will be basically free, so any battery can be charged during these periods at little cost. Wait and see if skeptical.

kayfox 9y ago

I think lowering the time cost of coming into the office would lead to more telecommuting than less. Since you can get into the office in 15 minutes, you don't have to go to the office every day just in case you need to have an impromptu meeting.

danielvf 9y ago

We do seem to have different value systems. I believe applying energy to make human lives better is a great thing! Electricity usage in the western world is getting greener fast. Total usage is going down, not up. This isn't going to reverse either of those trends. There's a popular perception that all aircraft burn energy like an oil refinery on fire. The reality is that small piston aircraft are approximately as fuel efficient as the vehicles around you on the highway (at least where I live) while getting you there a whole lot faster. A Cirrus is a good comparison stand in for the KittyHawk aircraft because it has a similar design and construction style (ignoring the dodeca-props), four seats, and is the most common general aviation aircraft not designed in the 1950's. A Cirrus isn't even close to the most energy efficient aircraft - that would be more like 60 mpg, nor is it the most efficient in its class.

deleted 9y ago
[deleted]
dzhiurgis 9y ago
> Electricity usage in the western world is getting greener fast. 81% of energy produced in NZ is renewable. Complex terrain would make such vehicle a saviour. Plus, in any terrain planes almost always travel less, so savings are intrinsic. Finally, using "taxi" name here is awful. At the most it's going to be an entertainment device initially (tourism and extremely expensive attractions are insane in NZ), method of access remote places later.
pc86 9y ago
> The reality is that small piston aircraft are approximately as fuel efficient as the vehicles around you on the highway This is just objectively wrong. Before taking wind into account, a Cessna 172 travels 120kts on a good day and at altitude and appropriately leaned can get down to 8 gallons an hour. 120 nautical miles in 140 miles (less, but benefit of the doubt and all). That's 17.5 miles per gallon. At cruise altitude. Leaned appropriately. You can tack on another few gallons for the climb, and you're going mixture rich on descent so you're back up to 10-11 gph for the last 20-30 miles of your trip. You're lucky to get 10mpg overall for a flight, and that's using gas that costs $5 a gallon. There are a LOT of benefits to GA flight in order to get around. Fuel efficiency is definitely not one of them.
- sixbrx 9y ago
  Well for the autos you need to consider that they may commonly be in rush hour traffic, too, stopped and idling quite a bit.
  - pc86 9y ago
    It's a good thing the EPA has highway fuel economy ratings then so we can compare apples to apples.
- DennisP 9y ago
  He specified "general aviation aircraft not designed in the 1950's." The Cessna 172 was first flown in 1955: https://en.wikipedia.org/wiki/Cessna_172 https://en.wikipedia.org/wiki/Cessna_172 Also, it may be worth taking into account that airplanes travel in straighter lines.
  - pc86 9y ago
    I'm talking about overall miles traveled so I'm not sure the straight line thing matters. Yes for the same trip you will travel a shorter distance in a plane. The plane will also be running for 20-30 minutes prior to takeoff and 5-10 minutes after landing. If you exclude GA aircraft not designed in the mid-20th century, you exclude 90% of GA aircraft and 99% of certified GA aircraft. We can make that distinction if you want but it ignores reality.
tripzilch 9y ago
> We do seem to have different value systems. I believe applying energy to make human lives better is a great thing! Your conclusion that we must have different value systems only shows where you stopped thinking. We differ in the timescale on which we consider the betterment of human lives. And we differ in the subset of human lives we consider the betterment of. If you remain convinced we have different value systems, then it's not about energy or the betterment of human lives (or straw lives), but about placing a low value on short-sightedness and egotism.

Kalium 9y ago

You're absolutely right. We should be encouraging density to save energy and be ecologically friendly. What's most wonderful is that we don't even need any new technologies to do it! It may be possible that this is something of a politically difficult problem in many areas, though. Until San Francisco actually allows itself to become a real city, we may be stuck looking at workarounds. It's very, very, very far from ideal. Exactly as you say. But it may be the best we can do for now.

deleted 9y ago

[deleted]

rukittenme 9y ago

The most efficient trip is the one not taken but what do we lose by not taking it? Is that cross town trip trivial, necessary, or serve a higher purpose? I don't think anyone would stop a human-rights march because of energy efficiency concerns. And who cares about energy efficiency when the energy is clean? It's well-known that the US is trending greener and this electric taxi is years away from widespread adoption.

marze 9y ago

Solar electricity will be nearly free shortly, so efficiency isn't an important issue. Cost still is of course. Solar is becoming so cheap that an excessive amount of generation will be installed, so adequate generation will be available in morning or evening, or with clouds. During peak sun, excess power will be basically free, so any battery can be charged during these periods at little cost. Wait and see if skeptical.