Why Electric Airplanes Face Such a Tough Haul [video]
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* 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%.
Obviously it would limit the airstrips from which an electric plane could embark, but maybe that's an acceptable trade-off.
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.
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...)
Passenger helicopters: speed 160 MPH, range 250 miles, cost $1.3-13.00 USD/mile
Joby claims: 200 MPH, 150 miles, ~$4 USD/mile.
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.
https://www.cnn.com/2019/06/10/us/new-york-city-helicopter-f...
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.
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.
This is brilliant: test in 3rd world b/c who cares about those anyway
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.
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.
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.
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.
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.
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.
[1] https://www.faa.gov/regulations_policies/advisory_circulars/...
https://www.faa.gov/about/office_org/headquarters_offices/an...
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...
Volume, though, is an issue and impacts aerodynamic design.
https://www.borntoengineer.com/hydrogen-powered-drone-sets-w...
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.
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.
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.
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.
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.
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.
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.
This is not a good thing for the environment.
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.
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?
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.
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.)
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.
Your idea will not work. Hydrogen storage, cells, and motors will weights many times the jet engine, or a plane itself
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'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.
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 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.
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.
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.
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.