Why Electric Airplanes Face Such a Tough Haul [video](youtube.com)
youtube.com
Why Electric Airplanes Face Such a Tough Haul [video]
https://www.youtube.com/watch?v=a717YZnhQ-s
93 comments
If I were starting an aerospace company (which is roughly the same as saying “if I hated money…”), I’d damn sure start it in the US. The US has very friendly rules for experimental R&D aircraft development, is the largest single market for aviation, and what the FAA requires for certification of production aircraft isn’t going to be substantially more involved than what they’d accept from another member ICAO state.
Aviation regulations are overwhelmingly federal in the US, so excepting any airport-specific rules, CA is an OK place to start.
If you’re capable of making electric airplanes viable, you’re capable of doing it in the FAA and CA jurisdiction.
Aviation regulations are overwhelmingly federal in the US, so excepting any airport-specific rules, CA is an OK place to start.
If you’re capable of making electric airplanes viable, you’re capable of doing it in the FAA and CA jurisdiction.
An unrelated reason why California is not great place for it: an aviation company I am familiar with recently had its entire test site (remote, desolate place) closed for months, because of fire risk — one of its previous prototypes caught on fire upon crashing (as things packed with energy sometimes to do on crash), and so no more testing was allowed until things get less dry.
California aerospace companies have usually conducted flight tests in the Mojave Desert area precisely because a crash is unlikely to cause a major fire or other damage on the ground.
If you're in Europe, you could do manufacturing in Italy as they have some kind of a special free trade agreement with USA regarding aircraft. Pipistrel is manufacturing some planes in Italy because of that.
Sure, but that doesn't really help anything. e.g. the AW609 mentioned in the video that has been stuck in certification for 20 years is built in Italy under that agreement.
> * I don't think the crash requirements need to compare to commercial aviation, but to cars. This is competing with cars.
Noone will accept any new technology that is as dangerous as cars. (And I sincerely hope at some point we will agree that we won't accept an old technology that's as dangerous as cars...)
Noone will accept any new technology that is as dangerous as cars. (And I sincerely hope at some point we will agree that we won't accept an old technology that's as dangerous as cars...)
Just to take issue with one piece of this, the crash requirements do need to compete with commercial aviation, because in the customer mindset they will.
> I don't think the crash requirements need to compare to commercial aviation, but to cars. This is competing with cars.
A lot of car crashes are not fatal. Would you be able to say the same of electric airplanes? I'm guessing fatality rate will be much higher, and with added collateral damage of a lithium ion bomb falling from the sky onto other cars, buildings, etc. the public will not tolerate electric plane crash rates the same as car crashes.
A lot of car crashes are not fatal. Would you be able to say the same of electric airplanes? I'm guessing fatality rate will be much higher, and with added collateral damage of a lithium ion bomb falling from the sky onto other cars, buildings, etc. the public will not tolerate electric plane crash rates the same as car crashes.
Take off power surge is one of the few areas that electric aircraft actually are well suited for. Batteries of specific power high enough are not uncommon.
The problem raised in the video was that high take-off power draw would age the batteries quickly, not that it was impossible. I haven't run the numbers to see if they were right.
I wonder if a low-performance version of a carrier catapult would work. Perhaps a simpler / cheaper version would be a specialized winch at the end of the runway.
Obviously it would limit the airstrips from which an electric plane could embark, but maybe that's an acceptable trade-off.
Obviously it would limit the airstrips from which an electric plane could embark, but maybe that's an acceptable trade-off.
Gliders are already launched using winches at some airfields.
https://www.camgliding.uk/about-gliding/launch-methods/
https://www.camgliding.uk/about-gliding/launch-methods/
That’s precisely what Zipline does, which is the only operational cargo electric plane company.
You could even have a cable that travels with the plane while it's on the runway providing all the power you need and when the plane takes off, the cable comes off and the plane uses its own battery.
But you’re starting off in the best possible part of the flight, when battery voltage is highest. A burst of power there has the least bad impact. Also, if you have a large battery, the amount of power you can afford for burst is extremely high. It’s also possible to have a battery optimized for high discharge assist the main battery, like a hybrid vehicle. But that’s unlikely for most battery chemistries which have plenty high C-rate that a secondary power-optimized battery is totally unnecessary.
Well, if you only do one flight per charge, yes. One of the club around here tried to use an electric plane for instruction, and the constant takeoff/landing cycles killed the battery real fast.
Could you have some kind of slingshot on the runway to accelerate the plane, take some of the work off the batteries? Like what they have on aircraft carriers.
Yeah, I mean you can put a bunch of AAA batteries in parallel to get an arbitrary amount of current!
I don't think it would be viable to do battery replacement. Pretty much no commercial EVs do it, partly because we don't need to, and partly because it's pretty hard problem. Battery packs have a pretty narrow range of temperature where they perform well so they need fluid lines to either heat or cool them, in addition to the electrical connections.
Plus with a plane, the only place that really makes sense to put the fuel or batteries is in the wings, so it couldn't be a flat pancake battery pack like in a passenger car. I don't think you could make a wing where you can remove the battery from the wing easily, it would have to be sealed in place.
So the only way I think that would really make sense would be for the fuselage to be removed from the wing assembly, and then re-attached to a fully charged wing assembly. And that doesn't seem that practical either.
Plus with a plane, the only place that really makes sense to put the fuel or batteries is in the wings, so it couldn't be a flat pancake battery pack like in a passenger car. I don't think you could make a wing where you can remove the battery from the wing easily, it would have to be sealed in place.
So the only way I think that would really make sense would be for the fuselage to be removed from the wing assembly, and then re-attached to a fully charged wing assembly. And that doesn't seem that practical either.
> A likely mistake seems to be trying to get this off-the-ground in the US regulatory climate. It'd be much easier to do this in a friendlier regime, more tolerant of occasional crashes, get experience, and move into Western markets after the concept is validated. California seems like just about the worst place to start.
I'm not sure this is as straight-forward as it sounds. Simply put, there's not many places you're going to find a high cash-density with low regulation.
Frankly - and I say this as a European - California is exactly where I'd want to launch this. You have the urban density to make it desirable, the cash-density to make it possible, and the most favourable year-round weather out of anywhere else I can think that'd make the list.
I'm not sure this is as straight-forward as it sounds. Simply put, there's not many places you're going to find a high cash-density with low regulation.
Frankly - and I say this as a European - California is exactly where I'd want to launch this. You have the urban density to make it desirable, the cash-density to make it possible, and the most favourable year-round weather out of anywhere else I can think that'd make the list.
Let me give a few examples of decent places to launch:
1) Dubai
2) Doha
3) Maybe Manama
4) Maybe Riyadh
Upsides:
- "Regulatory regime" means that you talk to the royal family. This is a surprisingly sane and reasonable process.
- Plenty of money to go around; people looking for things to invest into when the oil runs out
- Better weather than California
- Culture is more tolerant of occasional crashes
- Cash-rich populations who would pay for this sort of thing
The market isn't as large, but for a pilot, you don't want large. For large markets, though, I can think of a few cities in Asia which would be ideal for scaling up.
As a footnote: Regulation isn't a question of low versus high. It's a question of easy versus hard. I worked in a highly-regulated field, and we did field testing in a small European country where the standards were probably higher than the US, but the process was much more streamlined. Approvals were done by talking to one expert who either gave a thumbs up, thumbs down, or told you what you needed to change. In the US, the process would have taken years of pushing paperwork, and a mechanical bureaucracy is less suited to evaluate safety than an expert. A multiyear process isn't necessarily any more robust than a fast one.
1) Dubai
2) Doha
3) Maybe Manama
4) Maybe Riyadh
Upsides:
- "Regulatory regime" means that you talk to the royal family. This is a surprisingly sane and reasonable process.
- Plenty of money to go around; people looking for things to invest into when the oil runs out
- Better weather than California
- Culture is more tolerant of occasional crashes
- Cash-rich populations who would pay for this sort of thing
The market isn't as large, but for a pilot, you don't want large. For large markets, though, I can think of a few cities in Asia which would be ideal for scaling up.
As a footnote: Regulation isn't a question of low versus high. It's a question of easy versus hard. I worked in a highly-regulated field, and we did field testing in a small European country where the standards were probably higher than the US, but the process was much more streamlined. Approvals were done by talking to one expert who either gave a thumbs up, thumbs down, or told you what you needed to change. In the US, the process would have taken years of pushing paperwork, and a mechanical bureaucracy is less suited to evaluate safety than an expert. A multiyear process isn't necessarily any more robust than a fast one.
To me "short-hop flights" is the real reason any of this makes sense. If you are commuting into NYC and can get picked up at 9am and flown past traffic to your building, thats an enormous win if you can pay for it. It will compete in helicopter taxi market and expand that market by being able to land closer to the destination because it makes less noise. This and its faster speed means shorter total commute.
Passenger helicopters: speed 160 MPH, range 250 miles, cost $1.3-13.00 USD/mile
Joby claims: 200 MPH, 150 miles, ~$4 USD/mile.
Passenger helicopters: speed 160 MPH, range 250 miles, cost $1.3-13.00 USD/mile
Joby claims: 200 MPH, 150 miles, ~$4 USD/mile.
Except that NYC is one of the worst environments in the world for short-hop flights, due to the risk of killing dozens of people on the ground if you crash.
The safety record of non-commercial aviation is not great.
If you want to solve traffic, invest in public transit. Matching the throughput of a single train requires completely saturating the sky with small aircraft.
The safety record of non-commercial aviation is not great.
If you want to solve traffic, invest in public transit. Matching the throughput of a single train requires completely saturating the sky with small aircraft.
There are only 3 helicopter pads available for commuter use in Manhattan. Those won't be able to handle much more traffic during commute hours. Building more isn't going to be politically viable.
https://www.cnn.com/2019/06/10/us/new-york-city-helicopter-f...
https://www.cnn.com/2019/06/10/us/new-york-city-helicopter-f...
> do this in a friendlier regime, more tolerant of occasional crashes, get experience, and move into Western markets
This is brilliant: test in 3rd world b/c who cares about those anyway
This is brilliant: test in 3rd world b/c who cares about those anyway
Take-off power surge: Maybe try catapult launch ? It wouldn't have to be as mechanically compact and precisely manufactured as an aircraft carrier's.
Exactly. Joby is just one of many. They might fail and probably will.
The reality: multiple companies are currently flying viable prototypes. A lot of the issues are at this point no longer issues: they are solved problems (or at least very solvable). The solutions might not be perfect but we are beyond proofs of concept at this point: these things are flying.
The math is known, brutal, but not a show stopper. In short, within acceptable parameters of e.g. limited range (but also cost), these things can function as advertised. There are a bunch of uncertainties remaining that are essentially non technical and boil down to regulation, market dynamics, and people buying into this stuff.
The main psychological issue is that people have been trained to believe that planes are complex machines that require advanced skills to fly, a lot of maintenance, and a high cost per hour/mile. While they are reluctant to let go of these notions, none of that is true for electrical planes. Think of them as a vacuum cleaners with wings and some power source (i.e. batteries or fuel cells). Simple to manufacture, maintain. and operate. Reliable too because there's very little that can break.
It's the exact opposite of the complex, unreliable, expensive to build and operate planes that we have today. Their unreliability requires constant vigilance in the form of maintenance, inspections, and vigilance that requires extensive practice and training. You are not even allowed to operate a plane unless you can prove that you have gone through extensive training and have enough recent experience flying a plane. Flying a plane requires deep knowledge of all the complex machinery, its failure modes, and mitigations.
Electrical planes not so much. The prototypes on the market right now have in common that they are "fly by wire" where pilot inputs are very limited and dumbed down to the point where you might wonder what the role of the pilot exactly is (some of these things are autonomous from day one). They are mechanically simple (lots of reliable electrical motors, wires, and batteries). And they cost a certain amount of $ per hours which is a function of the (long) mechanical life of the engines and the rest of the plane and the cost of KWH.
The main argument in this video is that the FAA is going to be a PITA. That's correct; that's their job and they are good at it. But that doesn't mean it's a constant in the universe. Ultimately some country will start allowing these things and likely at that point FOMO and politics kick in. Simply put, if e.g. China (a likely place for this to happen) starts living in the future by manufacturing and operating these things at scale, there's absolutely zero chance of the FAA being allowed to hold that back in the USA for very long.
The reality: multiple companies are currently flying viable prototypes. A lot of the issues are at this point no longer issues: they are solved problems (or at least very solvable). The solutions might not be perfect but we are beyond proofs of concept at this point: these things are flying.
The math is known, brutal, but not a show stopper. In short, within acceptable parameters of e.g. limited range (but also cost), these things can function as advertised. There are a bunch of uncertainties remaining that are essentially non technical and boil down to regulation, market dynamics, and people buying into this stuff.
The main psychological issue is that people have been trained to believe that planes are complex machines that require advanced skills to fly, a lot of maintenance, and a high cost per hour/mile. While they are reluctant to let go of these notions, none of that is true for electrical planes. Think of them as a vacuum cleaners with wings and some power source (i.e. batteries or fuel cells). Simple to manufacture, maintain. and operate. Reliable too because there's very little that can break.
It's the exact opposite of the complex, unreliable, expensive to build and operate planes that we have today. Their unreliability requires constant vigilance in the form of maintenance, inspections, and vigilance that requires extensive practice and training. You are not even allowed to operate a plane unless you can prove that you have gone through extensive training and have enough recent experience flying a plane. Flying a plane requires deep knowledge of all the complex machinery, its failure modes, and mitigations.
Electrical planes not so much. The prototypes on the market right now have in common that they are "fly by wire" where pilot inputs are very limited and dumbed down to the point where you might wonder what the role of the pilot exactly is (some of these things are autonomous from day one). They are mechanically simple (lots of reliable electrical motors, wires, and batteries). And they cost a certain amount of $ per hours which is a function of the (long) mechanical life of the engines and the rest of the plane and the cost of KWH.
The main argument in this video is that the FAA is going to be a PITA. That's correct; that's their job and they are good at it. But that doesn't mean it's a constant in the universe. Ultimately some country will start allowing these things and likely at that point FOMO and politics kick in. Simply put, if e.g. China (a likely place for this to happen) starts living in the future by manufacturing and operating these things at scale, there's absolutely zero chance of the FAA being allowed to hold that back in the USA for very long.
> A likely mistake seems to be trying to get this off-the-ground in the US regulatory climate. It'd be much easier to do this in a friendlier regime, more tolerant of occasional crashes, get experience, and move into Western markets after the concept is validated. California seems like just about the worst place to start.
Where would this “more friendly” regulatory climate exist and how to you get the best aerospace engineers in the world there?
There’s nothing to prevent this company from testing models in California, and unmanned. What’s the point of starting somewhere that lets you kill test pilots with fewer consequences.
This is mastabatory libertarian bullshit. No high tech startup wins and loses on regulation.
Where would this “more friendly” regulatory climate exist and how to you get the best aerospace engineers in the world there?
There’s nothing to prevent this company from testing models in California, and unmanned. What’s the point of starting somewhere that lets you kill test pilots with fewer consequences.
This is mastabatory libertarian bullshit. No high tech startup wins and loses on regulation.
Is there some reason we can't just use biofuels in existing planes? They're more expensive, but they're not that much more expensive.
And you could do this immediately instead of having to either scrap every existing plane or wait 30+ years until they all age out.
We could at least do this until someone gets electric planes to work, whether or not that ever happens, and continue doing it during the transition. Which would then happen faster when the legacy planes have a higher fuel cost.
And you could do this immediately instead of having to either scrap every existing plane or wait 30+ years until they all age out.
We could at least do this until someone gets electric planes to work, whether or not that ever happens, and continue doing it during the transition. Which would then happen faster when the legacy planes have a higher fuel cost.
Yes carbon neutral synthetic liquid kerosene is the clear path forward for long haul flights. It is safe, requires no changes to aviation infrastructure, and has already been tested in civil and military aircraft.
https://www.cnet.com/roadshow/news/united-becomes-first-airl...
Weight and energy density obstacles will limit electric propulsion to short range flights for the near future. There could also be a use case for hybrid aircraft where electric motors are used to assist the initial take off and climb, then turned off for cruise.
https://www.cnet.com/roadshow/news/united-becomes-first-airl...
Weight and energy density obstacles will limit electric propulsion to short range flights for the near future. There could also be a use case for hybrid aircraft where electric motors are used to assist the initial take off and climb, then turned off for cruise.
It is my understanding that fuel composition is a part of engine approval, and it is similar to authorizing a new part if you are using a new fuel. [1] It seems the FAA only recently approved the use of unleaded gasoline for a large number of engines! [2] So while bio-fuel based fuels would be great, there does seem to be some significant, and I think reasonable, bureaucracy in the way of that happening.
[1] https://www.faa.gov/regulations_policies/advisory_circulars/...
[2] https://www.faa.gov/about/initiatives/avgas
[1] https://www.faa.gov/regulations_policies/advisory_circulars/...
[2] https://www.faa.gov/about/initiatives/avgas
Most fuel for aviation is jet fuel, and there already is a "drop in" approved biofuel available:
https://www.faa.gov/about/office_org/headquarters_offices/an...
https://www.faa.gov/about/office_org/headquarters_offices/an...
Thanks for the clarification!
I think the fermentation process of getting the bioethanol is not as carbon-neutral as we hoped. Then there is the issue of monoculture (although that is a problem with more industries).
https://www.youtube.com/watch?v=OpEB6hCpIGM
https://www.youtube.com/watch?v=OpEB6hCpIGM
So this is to help people skip traffic. Assuming it's successful, wont this create new bottlenecks at these pickup/dropoff areas? Reminds me of adding more lanes to a highway. It doesn't really solve anything, just diverts more people to the highway.
America is obsessed with parking garages. Most cities have no shortage of parking garages whose rooftops could be used as landing sites.
Front-Electric Sustainer (FES) is changing the face of gliding: https://news.ycombinator.com/item?id=29703685
About 20x more expensive at 1/3 the speed vs commercial jet; 40x more expensive at 2x the speed of a car.[1][2][3] Car has 10x the range between refuelings and can stop at almost any building. This will presumably be limited to heliports, of which there are presently ~ 6,000 in the U.S.[4]
It's really a quieter / more comfortable helicopter. Helicopters have seen limited use. Will lower noise change that?
Edit: The dominant cost factor across modalities seems to be seats per pilot. It's infinite for cars modulo parking; in the hundreds for commercial jets; dozens for busses; single digits for taxis and small aircraft. Of course it's always been understood that ridesharing needs autonomy to be truly profitable, and from the slides it seems Joby acknowledge this as well. Autonomy may be easier in the sky...
[1] https://www.youtube.com/watch?v=a717YZnhQ-s&t=700s
[2] https://en.wikipedia.org/wiki/Available_seat_miles
[3] https://news.ycombinator.com/item?id=19574388
[4] https://en.wikipedia.org/wiki/List_of_countries_by_number_of...
It's really a quieter / more comfortable helicopter. Helicopters have seen limited use. Will lower noise change that?
Edit: The dominant cost factor across modalities seems to be seats per pilot. It's infinite for cars modulo parking; in the hundreds for commercial jets; dozens for busses; single digits for taxis and small aircraft. Of course it's always been understood that ridesharing needs autonomy to be truly profitable, and from the slides it seems Joby acknowledge this as well. Autonomy may be easier in the sky...
[1] https://www.youtube.com/watch?v=a717YZnhQ-s&t=700s
[2] https://en.wikipedia.org/wiki/Available_seat_miles
[3] https://news.ycombinator.com/item?id=19574388
[4] https://en.wikipedia.org/wiki/List_of_countries_by_number_of...
Their release schedule is laughable and not real. Cessna was proceeded by 50 years of prior art of almost exactly the same vehicle that electric planes do NOT have.
Hydrogen is the way for aircraft / long-haul vehicles. It's not about conversion efficiency it's about energy density v weight.
Why does an electric airplane need to use batteries for storage? I'd say advance the technology by using other sources of power if possible.
Instead of compressed liquid hydrogen which is hard to contain maybe some type of heated metal-hydride using hydrogen. Convert with a fuel cell, maybe batteries as a buffer and for their efficiency. Event that weird PowerPaste stuff may be suitable too. https://en.wikipedia.org/wiki/Powerpaste
I've seen 30kWh to 50kWh per 100kg of hydrogen metal hydride. The linked says says Tesla is about 75kWh per 453kg (1,000 lbs) and the Joby S4 claims 150kWh 907kg (2,000 lbs). Batteries would be more efficient but if hydrogen metal-hydride is 50kWh/100kg a Tesla could have 340kWh at the same weight of storage or lose 300kg and still have 75kWh.
Instead of compressed liquid hydrogen which is hard to contain maybe some type of heated metal-hydride using hydrogen. Convert with a fuel cell, maybe batteries as a buffer and for their efficiency. Event that weird PowerPaste stuff may be suitable too. https://en.wikipedia.org/wiki/Powerpaste
I've seen 30kWh to 50kWh per 100kg of hydrogen metal hydride. The linked says says Tesla is about 75kWh per 453kg (1,000 lbs) and the Joby S4 claims 150kWh 907kg (2,000 lbs). Batteries would be more efficient but if hydrogen metal-hydride is 50kWh/100kg a Tesla could have 340kWh at the same weight of storage or lose 300kg and still have 75kWh.
Storing a lot of hydrogen at high pressure requires heavy tanks. Storing a lot of hydrogen at low pressure results in the Hindenburg.
So, no one would ever use compressed hydrogen for transport aircraft. LH2 tanks weigh practically nothing.
We already have drones that can hover for hours using hydrogen in carbon fiber tanks...
https://www.borntoengineer.com/hydrogen-powered-drone-sets-w...
https://www.borntoengineer.com/hydrogen-powered-drone-sets-w...
Tiny aircraft have an enormous advantage over those big enough to move much.
It is easy to make an RC plane that can fly straight up. Or, an ornithopter. A 747 flying straight up is impossible. A 747-sized ornithopter is impossible.
Those "tictacs" swooping around navy ships are most likely liquid-fueled drones. If they haven't shot any down yet, that is a disgrace.
It is easy to make an RC plane that can fly straight up. Or, an ornithopter. A 747 flying straight up is impossible. A 747-sized ornithopter is impossible.
Those "tictacs" swooping around navy ships are most likely liquid-fueled drones. If they haven't shot any down yet, that is a disgrace.
> LH2 tanks weigh practically nothing.
Volume, though, is an issue and impacts aerodynamic design.
Volume, though, is an issue and impacts aerodynamic design.
The weight advantage will prove decisive. On routes served by LH2-fueled transports, the kerosene-fueled dinosaurs will be wholly unable to compete.
you need to either compress or cryogenically cool. At 1atm and normal temp, hydrogen is about 8x less energy per volume then her fuel.
Volume is cheap, in aircraft. Weight is dear.
Electric flight today is always about short-haul flight, ranging from air-taxi eVTOLs like Joby to more normal planes like Eviation's Alice, but all less than 1000km in range.
If they didn't face a tough haul, we'd all be flying in them already.
I'm very bullish on electric flight, both eVTOL (Joby, Lillium, etc) and normal planes (Eviation, etc), and these things will revolutionize transit the way we can't quite appreciate. Not only will they displace any notions of HSR in developed places like North America (it is already a non-starter, but too many people still have illusions around it), it'll also connect places with HSR-like transit which would never even be considered for a line. By being able to connect a multitude of smaller cities, it'll allow even more out-migration from cities by people with mobile jobs.
Number one risk is not technological here, it is likely plain old NIMBYism. I'm sure we'll see a set of contradictory and impossible to meet demands done in the name of "safety" but masking plain old greed, selfishness or just being a reactionary.
I'm very bullish on electric flight, both eVTOL (Joby, Lillium, etc) and normal planes (Eviation, etc), and these things will revolutionize transit the way we can't quite appreciate. Not only will they displace any notions of HSR in developed places like North America (it is already a non-starter, but too many people still have illusions around it), it'll also connect places with HSR-like transit which would never even be considered for a line. By being able to connect a multitude of smaller cities, it'll allow even more out-migration from cities by people with mobile jobs.
Number one risk is not technological here, it is likely plain old NIMBYism. I'm sure we'll see a set of contradictory and impossible to meet demands done in the name of "safety" but masking plain old greed, selfishness or just being a reactionary.
If legal hurdles were more important than technological ones, we could expect to see a boom of electric flight somewhere else. Unlike technology, legal environment differs a lot across the globe, and if the technology is hopeful enough, someone will start adapting it soon. Gone are the times when all technological development was happening just in a few countries.
Electric helicopters taking off and landing in your neighborhood is not the same old NIMBYism which delayed Caltrain electrification for years. There is ample evidence for the negative health effects of persistent noise pollution, and helicopters are the worst offenders of noise pollution.
Perhaps these eVTOL planes will reduce noise to an acceptable levels, however that remains to be seen, and until they have proven they can, then I’ll believe the NIMBYs complaints.
Perhaps these eVTOL planes will reduce noise to an acceptable levels, however that remains to be seen, and until they have proven they can, then I’ll believe the NIMBYs complaints.
> it'll allow even more out-migration from cities by people with mobile jobs.
This is not a good thing for the environment.
This is not a good thing for the environment.
It could be a good thing. The invention of both catalytic converts and non-ozone destroying alternatives to CFCs have done great things for the environment but required large amounts of human collaboration to invent.
Making it easier for people to come together and invent / perfect new tech can have huge benefits.
It's likely that we will solve climate change through technology like carbon capture rather than simply by reducing/curtailing energy usage.
Making it easier for people to come together and invent / perfect new tech can have huge benefits.
It's likely that we will solve climate change through technology like carbon capture rather than simply by reducing/curtailing energy usage.
>It's likely that we will solve climate change through technology like carbon capture rather than simply by reducing/curtailing energy usage.
Maybe. But that can't be used as an excuse to not even attempt to curtail energy usage.
And I mean sure, it's possible that the agglomeration effects from such travel would 1) be more significant than what is already available via remote work over the internet, 2) be significant enough to offset the increased energy usage from the increased travel itself and building all the infrastructure for even greater sprawl, 3) result in technology that somehow solves climate change but doesn't have the same social forces against it as the technology we have today that's better than the status quo. But that's a lot of assumptions. Do you really want to bet the planet on it?
Maybe. But that can't be used as an excuse to not even attempt to curtail energy usage.
And I mean sure, it's possible that the agglomeration effects from such travel would 1) be more significant than what is already available via remote work over the internet, 2) be significant enough to offset the increased energy usage from the increased travel itself and building all the infrastructure for even greater sprawl, 3) result in technology that somehow solves climate change but doesn't have the same social forces against it as the technology we have today that's better than the status quo. But that's a lot of assumptions. Do you really want to bet the planet on it?
I would much rather bet the planet on technology rather than an attempt to curtail energy usage. We've never curtailed energy usage in the history of humanity. It's foolhardy to expect to reverse a trend that has persisted for millennia.
Be serious. HSR is capable of dumping half a million people per hour into stations that occupy less than 100 acres. In no way is eVTOL (which does not even exist!) a substitute good for HSR.
You know the old question "Why go to the moon instead of solving world hunger?" Well, the answer is that despite going to the moon being a incredibly hard technological problem, it is still vastly easier than solving world hunger. Likewise, eVTOLs are a very hard technological problem, but that is nothing compared to the social problems of getting new rail lines built in North America.
So yeah, I think the only unserious people are those dreaming of HSR in North America. Vast structural challenges and repeated high-profile failures don't seem to bring about any introspection or doubt, just more doubling-down. Privately built and operated eVTOLs fit smoothly into the structure of our society. Expropriating vast amounts of land to connect city centres while people live in the burbs does not fit nearly so well. Developing better batteries is vastly, vastly simpler and easier than restructuring all of society around fixed rail lines.
So yeah, I think the only unserious people are those dreaming of HSR in North America. Vast structural challenges and repeated high-profile failures don't seem to bring about any introspection or doubt, just more doubling-down. Privately built and operated eVTOLs fit smoothly into the structure of our society. Expropriating vast amounts of land to connect city centres while people live in the burbs does not fit nearly so well. Developing better batteries is vastly, vastly simpler and easier than restructuring all of society around fixed rail lines.
Interestingly, eVTOLs are likely the answer to solving world hunger. We are already able to easily cultivate more than enough calories to feed the world, the problem is efficient distribution. Cheap air-based transport could go a long way in solving the distribution problem.
Rail is just very hard to do. I’m curious if it will end up really being worth it for China. The cost of maintenance and how centralized it is seems much worse than airports. Like Boise Idaho is booming right now, right? Well, its airport can just add some terminals for costs that the local tax base can support. Want to connect it via HSR? Okay, be prepared to spent a hundred billion dollars, for a slower ride that almost always needs a transfer.
It just sounds like you are dedicated to underestimating the cost of airports and overestimating the costs of railroads. Boise is admittedly an extreme example because of its isolation, but it is within practical HSR distance of Salt Lake City, Portland, and Reno. Can't see why you'd need a transfer for any of the above. Anyway air service Boise-to-Reno has no non-stop option, either.
This is a very common mistake people make with California's SF-LA HSR. They say it costs a lot. We should just build airports. But they don't seem to know that airport capacity sufficient to provide as many trips as CAHSR will be capable of providing is estimated to cost over $300 billion, much more than the entire rail project.
This is a very common mistake people make with California's SF-LA HSR. They say it costs a lot. We should just build airports. But they don't seem to know that airport capacity sufficient to provide as many trips as CAHSR will be capable of providing is estimated to cost over $300 billion, much more than the entire rail project.
If there isn’t even a flight to Reno, why would HSR make sense?
>end up really being worth it for China.
PRC air corridors are heavily congested - huge population concentrated on coastal regions + priority access for military aviation which also has to concentrate on coast for defense = massive delays for short hull trips that makes HSR come out ahead. Chinese military watchers occasionally joke that successfully invading TW and moving military aviation further out the 1st island chain would increase efficiency of domestic flights. Except there's probably some truth to it. Maintenance shouldn't be an issue, there's going to be low cost labour and extra infra capacity in PRC for a long time, even accounting for demographic concerns.
PRC air corridors are heavily congested - huge population concentrated on coastal regions + priority access for military aviation which also has to concentrate on coast for defense = massive delays for short hull trips that makes HSR come out ahead. Chinese military watchers occasionally joke that successfully invading TW and moving military aviation further out the 1st island chain would increase efficiency of domestic flights. Except there's probably some truth to it. Maintenance shouldn't be an issue, there's going to be low cost labour and extra infra capacity in PRC for a long time, even accounting for demographic concerns.
Interesting, sounds like PRC benefits from HSR in a way that even Europe or Japan don’t.
1. Due to the need to accelerate, HSR is only really good for 100 mile+ trips, beyond the range eVTOLs are being proposed for.
2. Hsr only goes point to point, stops and door to door transport isn’t really feasible, and those last couple of miles take a lot of the time.
3. HSR is extraordinarily expensive in infrastructure costs and most city pairs don’t have the passenger volume to justify it.
2. Hsr only goes point to point, stops and door to door transport isn’t really feasible, and those last couple of miles take a lot of the time.
3. HSR is extraordinarily expensive in infrastructure costs and most city pairs don’t have the passenger volume to justify it.
The USA has a unique impediment when it comes to HSR. In other countries the economics work not because they are selling tickets but because it frees up the conventional lines to be dedicated to cargo. In the USA most lines are privately owned and dedicated to cargo already.
How will these planes succeed when point-to-point helicopter service has not proven to be a widespread success? What is the key difference between what Joby is planning and Uber's helicopter service (using already FAA approved helicopters and regular fuel)?
Expense is a major factor for helicopters. Helicopters vibrate so much that many require a complete airframe overhaul after some number of hours. From this POV they are actually a very expensive consumable good themselves on top of the high fuel burn required.
So the economics of the point-to-point air ride hailing industry comes down to the cost of the flying equipment? Given Uber is operating at a substantial loss, is this the primary reason why their Uber-Air service isn't working out? I suspect it's more than just the cost of helicopters and their maintenance.
There aren’t that many places where “drive to an airport/heliport [or landowner and local ordinances approved landing area], get flown to another one, and then finish your journey from there” is a massive convenience.
Commuting from an office building with a helipad to an airport to catch a private jet? Makes sense if ground transport is 45+ minutes.
Building a helipad on your lake property and commuting to the local airport via helicopter? Makes sense if the local airport is 45+ minutes away, but otherwise it seems like a car is a better option.
I just don’t see that many helicopter flight pairs making sense to justify having a lot of on-demand helicopters. (And if you don’t have enough to make the latency low, it makes even less sense to the users.)
Commuting from an office building with a helipad to an airport to catch a private jet? Makes sense if ground transport is 45+ minutes.
Building a helipad on your lake property and commuting to the local airport via helicopter? Makes sense if the local airport is 45+ minutes away, but otherwise it seems like a car is a better option.
I just don’t see that many helicopter flight pairs making sense to justify having a lot of on-demand helicopters. (And if you don’t have enough to make the latency low, it makes even less sense to the users.)
So then how would Joby's service be any different than the above? Seems like the same problems to me. Gotham Air attempted this sort of service but went bust, and now the website just bounces to google.com
Honestly, I think Joby’s not likely to even get to the point where they fail at that part of the problem, but I agree with you that’s another significant filtering point before success.
They’re also way, way harder to pilot than planes, noisier, and slower.
I don't understand why hydrogen fuel cells are not investigated for electric planes - it's a mature enough technology that you can get it in consumer cars, it doesn't suffer from the same weight penalty of batteries. If you put the powertrain of a hydrogen powered Honda Clarity in a Cessna 172, I'm sure it would work.
They are:
https://www.airbus.com/en/innovation/zero-emission/hydrogen/...
The thing is - all carbon free options for aviation come with their downsides. Producing hydrogen creates a lot more conversion losses than using batteries, so when you can get along with a battery you will. Hydrogen will likely be used in the mid-range sector though.
The thing is - all carbon free options for aviation come with their downsides. Producing hydrogen creates a lot more conversion losses than using batteries, so when you can get along with a battery you will. Hydrogen will likely be used in the mid-range sector though.
True - but hydrogen is still immensely cleaner than the jet fuel powered planes we have today. And for aircraft the weight savings could lead to the aircraft carrying more useful cargo, which would probably offset the efficiency loss.
Edit: The link you provided describes hydrogen-combustion engines, not fuel-cell airplanes, which is also a promising concept, but not what I'm proposing.
Edit: The link you provided describes hydrogen-combustion engines, not fuel-cell airplanes, which is also a promising concept, but not what I'm proposing.
That's generally not true in practice today. Most hydrogen is produced from fossil fuels, so in most respects it's not any cleaner than just burning the fuel directly.
In theory it is possible to produce hydrogen from clean energy without using fossil fuels. But we're a long way from doing that at scale.
There is no real weight savings from hydrogen fuel once you account for the tankage, plus the more powerful engines needed to overcome the additional drag from those larger tanks.
In theory it is possible to produce hydrogen from clean energy without using fossil fuels. But we're a long way from doing that at scale.
There is no real weight savings from hydrogen fuel once you account for the tankage, plus the more powerful engines needed to overcome the additional drag from those larger tanks.
"No weight savings" - In a reply to another commenter, if we compare the tank of the Honda Clarity FCEV with the Model 3s battery, it seems that hydrogen is more than 3x more as wrt. space for the same energy output as batteries - so if they can fit those, these will fit as well.
LH2 tanks hardly weigh anything.
You must be talking about compressed gas, which of course would be obviously useless for aviation. So when anyone mentions hydrogen in connection with aviation, they do not mean compressed gas.
You must be talking about compressed gas, which of course would be obviously useless for aviation. So when anyone mentions hydrogen in connection with aviation, they do not mean compressed gas.
They have been experimented with for decades (I remember reading about 1970s prototypes as a kid in the 80s) but I believe it's stalled on energy density, very similar to batteries. In aircraft, the big factor is storage: if you had a robust storage system you could get more power from burning the hydrogen in a turbine but hydrogen is hard to store safely without very heavy containers.
I remember the Soviets converted a plane for hydrogen combustion:
https://en.wikipedia.org/wiki/Tupolev_Tu-155
But I feel that's a bit of a distraction - turbines must use thermodynamic cycles to convert fuel into thrust - something whose maximum efficiency is less than the real world efficiency of a hydrogen fuel cell.
I feel like hydrogen turbofans are not practical for small craft for a number of reasons - cost, maintenance, noise, limited start/stop cycles etc., while electrics have the ability to scale to every aircraft category.
But I feel that's a bit of a distraction - turbines must use thermodynamic cycles to convert fuel into thrust - something whose maximum efficiency is less than the real world efficiency of a hydrogen fuel cell.
I feel like hydrogen turbofans are not practical for small craft for a number of reasons - cost, maintenance, noise, limited start/stop cycles etc., while electrics have the ability to scale to every aircraft category.
The maximum efficiency hydrogen to electricity conversion is around on around 50% for real world fuel cells. This is around efficiency of GE90.
Your idea will not work. Hydrogen storage, cells, and motors will weights many times the jet engine, or a plane itself
Your idea will not work. Hydrogen storage, cells, and motors will weights many times the jet engine, or a plane itself
An LH2 tank hardly weighs anything. They even put them in rockets.
But they take up more room than would fit in the wings. They probably would need to be in nacelles slung under the wings like the engines.
But they take up more room than would fit in the wings. They probably would need to be in nacelles slung under the wings like the engines.
I'm aware that rockets have them but we have much stronger safety standards for passenger airplanes than we do for rockets. What I've heard is that it's very hard to build a hydrogen tank which is both lightweight and safe enough in the event of a crash or other incident to meet general civilian aviation standards.
I'd love to be wrong on that but given the obvious appeal there must be some thorny engineering challenges for an idea which has been batted around since the 1950s.
I'd love to be wrong on that but given the obvious appeal there must be some thorny engineering challenges for an idea which has been batted around since the 1950s.
You are hearing confused echoes.
The high-pressure hydrogen tanks needed for H2-fueled cars and trucks are difficult, in a place where using LH2 instead would be wholly impractical. LH2 tanks of a size appropriate for transport aircraft are trivial: thin-walled aluminum shrouded in insulation. LH2 for transport aircraft suffers none what would make it impractical for cars: it is always used immediately, and would be synthesized on demand right at the airport. Risk of exploding leaks is easily eliminated by positive ventilation; if it can't build up, it can't ignite; if it doesn't ignite, it can't explode.
In nacelles attached to the wing, alongside the engines, any extra safety concerns would be moot. Kerosene fuel is carried in wing tanks so that the wings shear off in a very bad landing and take the fuel away with them. A whole separate tank shears off much more easily than a wing.
The high-pressure hydrogen tanks needed for H2-fueled cars and trucks are difficult, in a place where using LH2 instead would be wholly impractical. LH2 tanks of a size appropriate for transport aircraft are trivial: thin-walled aluminum shrouded in insulation. LH2 for transport aircraft suffers none what would make it impractical for cars: it is always used immediately, and would be synthesized on demand right at the airport. Risk of exploding leaks is easily eliminated by positive ventilation; if it can't build up, it can't ignite; if it doesn't ignite, it can't explode.
In nacelles attached to the wing, alongside the engines, any extra safety concerns would be moot. Kerosene fuel is carried in wing tanks so that the wings shear off in a very bad landing and take the fuel away with them. A whole separate tank shears off much more easily than a wing.
it doesn't suffer a weight penalty, but it does suffer a volume penalty. it's also not that light since you need a lot of metal to keep hydrogen at the type of pressure you need.
I did a bit of googling at it seems that the 2016 Honda Clarity has a 141L tank, that gives it a range of 366 miles, while the Tesla Model 3 Standard Range Plus has a 334L battery, which gives it a range of 267 miles. So even if my numbers are off by a bit, the volume of hydrogen tanks is not a prohibitive factor.
* With short-hop flights. Swap out batteries at the destination, and slow-charge
* Endurance. You don't want batteries discharging below 20%. In an emergency, you do.
* Take-off power surge. Super-cap, ground effect, or plug-in power supply during take-off.
* I don't think the crash requirements need to compare to commercial aviation, but to cars. This is competing with cars.
I'm not saying Joby will get this right, but I think eventually, someone will.
A likely mistake seems to be trying to get this off-the-ground in the US regulatory climate. It'd be much easier to do this in a friendlier regime, more tolerant of occasional crashes, get experience, and move into Western markets after the concept is validated. California seems like just about the worst place to start.
As an investment, if you think they have a 1% chance of becoming Tesla, that merits a $10B valuation to be risk-neutral. The investment levels don't seem crazy. Personally, I wouldn't place their odds at anywhere close to 50%, but I'd place them at much greater than 1%.