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A 3x increase in density does approximately nothing to make electric airliners more viable. We need more like a 100x increase before we see an electric 737 or A

A 3x increase in density does approximately nothing to make electric airliners more viable. We need more like a 100x increase before we see an electric 737 or A320.

alkonaut 6y ago
This is the second time in this discussion someone mentions electric planes being viable and you respond with electric airliners not being viable. Those are (in most peoples terminology) entirely different things. Having viable light electric aircraft could revolutionize flight even if every aircraft for more than 20 people would run on kerosene for the next century. I don’t think anyone is expecting a battery powered 737 any time soon. But a battery powered Cessna 172 with a 30 minute range would be huge.
- cmrdporcupine 6y ago
  This. Enhancing drone flight times, or other automated/semi-automated airborne machinery would be an absolutely huge win for industry and commerce as a whole.
- 0xffff2 6y ago
  I can state from experience that you're mistaken in what you think people expect. I work in a field very closely aligned with electric aircraft, and people who say "electric planes" without further qualification virtually always mean "electric 737s". I also strongly question your assertion that viable light electric aircraft could "revolutionize flight". What exactly would the revolutionize? 2 seat electric trainers already exist, but the niche they fill is tiny. You're not going to move the needle on aircraft emissions with anything short of electric airliners. The rest of it is just a way to keep the research funded until we get there.
Obi_Juan_Kenobi 6y ago
An electric airliner would be able to operate at much higher altitudes, and thus much more efficiently. Looking only at energy density is naive.
audunw 6y ago
100x increase? Is that based on calculation based on the energy density of fuel vs batteries alone? Because there's a lot of efficiencies to be gained if you make a battery electric plane from scratch. And are you considering only a fully fuelled plane? Because many routes will only use a small fraction of the potential fuel capacity. Look at the Maxwell X-57 for instance. If you don't have fuel in the wings, and you can use small electric take-off propellers on the wings, you can make the wing much thinner, which reduces drag. You can potentially fly higher with electric planes, since you no longer have to think about air densitys impact on engine efficiency. The main challenge with electric airplanes is not really the batteries. You could probably make viable short-haul planes with todays technology. The problem is you're basically starting from scratch, as a plane optimised for electric engines is most likely vastly different from a 737 airframe. It'll take decades to design and optimize radically new airframes. We might never see planes crossing the pacific ocean with batteries only, but that doesn't mean electric planes aren't viable. By some calculations you can do 500-1000km routes with todays battery tech already, and there's a shitload of those. Maybe you'll have to fly 2-3 smaller planes rather than one huge one to cover the same route, but that can be a good thing. You could use smaller and more local airports. Electric planes are much more quiet after all. Operating costs with electric planes are way lower, so it might not be more expensive either. With a 3x+ capacity you can start talking about covering most of the routes within a continent. So what if you can't do transcontinental? I think we can make enough biofuel to cover that if most other flights are electric (and/or hydrogen)

A 3x increase in density does approximately nothing to make electric airliners more viable. We need more like a 100x increase before we see an electric 737 or A320.

alkonaut 6y ago

This is the second time in this discussion someone mentions electric planes being viable and you respond with electric airliners not being viable. Those are (in most peoples terminology) entirely different things. Having viable light electric aircraft could revolutionize flight even if every aircraft for more than 20 people would run on kerosene for the next century. I don’t think anyone is expecting a battery powered 737 any time soon. But a battery powered Cessna 172 with a 30 minute range would be huge.

cmrdporcupine 6y ago
This. Enhancing drone flight times, or other automated/semi-automated airborne machinery would be an absolutely huge win for industry and commerce as a whole.
0xffff2 6y ago
I can state from experience that you're mistaken in what you think people expect. I work in a field very closely aligned with electric aircraft, and people who say "electric planes" without further qualification virtually always mean "electric 737s". I also strongly question your assertion that viable light electric aircraft could "revolutionize flight". What exactly would the revolutionize? 2 seat electric trainers already exist, but the niche they fill is tiny. You're not going to move the needle on aircraft emissions with anything short of electric airliners. The rest of it is just a way to keep the research funded until we get there.

Obi_Juan_Kenobi 6y ago

An electric airliner would be able to operate at much higher altitudes, and thus much more efficiently. Looking only at energy density is naive.

audunw 6y ago

100x increase? Is that based on calculation based on the energy density of fuel vs batteries alone? Because there's a lot of efficiencies to be gained if you make a battery electric plane from scratch. And are you considering only a fully fuelled plane? Because many routes will only use a small fraction of the potential fuel capacity. Look at the Maxwell X-57 for instance. If you don't have fuel in the wings, and you can use small electric take-off propellers on the wings, you can make the wing much thinner, which reduces drag. You can potentially fly higher with electric planes, since you no longer have to think about air densitys impact on engine efficiency. The main challenge with electric airplanes is not really the batteries. You could probably make viable short-haul planes with todays technology. The problem is you're basically starting from scratch, as a plane optimised for electric engines is most likely vastly different from a 737 airframe. It'll take decades to design and optimize radically new airframes. We might never see planes crossing the pacific ocean with batteries only, but that doesn't mean electric planes aren't viable. By some calculations you can do 500-1000km routes with todays battery tech already, and there's a shitload of those. Maybe you'll have to fly 2-3 smaller planes rather than one huge one to cover the same route, but that can be a good thing. You could use smaller and more local airports. Electric planes are much more quiet after all. Operating costs with electric planes are way lower, so it might not be more expensive either. With a 3x+ capacity you can start talking about covering most of the routes within a continent. So what if you can't do transcontinental? I think we can make enough biofuel to cover that if most other flights are electric (and/or hydrogen)