Interesting. Obviously this is challenging from a power and energy density point of view but I suspect the play is likely to be in being able to land planes at airports very close in to major cities where noise and pollution constraints dominate. If you have a plane that you're allowed to land 300 times a year at midnight at a field where you'd only be allowed to land at 50 times a year before 10pm with a conventionally powered plane you might be able to stake out a commercially viable niche.
> I suspect the play is likely to be in being able to land planes at airports very close in to major cities where noise and pollution constraints dominate.
Midnight arrival at the destination isn't the problem. It's 6am departure from whoever your vacation house that's the pain point for people who are rich enough to be chartering jets and helicopters.
With an electric jet you can depart from Long Island or Cape Cod in time to arrive at your office on Wall Street for that Monday morning video conference with your business partners in Zurich and do so without annoying your neighbors.
With a conventional jet/turboprop/helicopter you're limited to about once or twice a month before your neighbors get annoyed with the early morning noise and sick the local bylaw Stasi on you. (This is the means by which people in these sorts of communities feud over minor inconveniences. If your constantly annoying people by chartering a jet at 5am they'll complain about the unsightliness of the sailboat under a carport in your driveway or something.)
An electric jet will be by no means quiet (gotta create thrust somehow) but an electric jet can be substantially quieter than a petroleum fueled jet (and noise reduction appears to be a quality they're specifically designing for). Being able to have the travel time of a jet but no more noise than a turboprop would probably a big enough selling point for a few charter companies to add a few to the fleet.
I used to work at one of these sorts of airports, early morning departures is the biggest pain point a quieter jet solves for the kind of people chartering jets (you can't just roar out of there at 5am every Monday without pissing people off).
Yes, however a large chunk of that is created by the flaps. If you have shape memory flaps, you can reduce noise by up to 40% on takeoff and landing. I know one company has already proven this technology on some Gulfstreams for qualification.
Electric is quieter than gas turbine. That I agree. But quiet enough to meet residential quiet time requirements is still up for debate. The quietest jackhammer in the world still can't run at night.
Hopefully these planes are some sort of VTOL and can descend within the confines of the airport property and zone. Current planes line up over residential neighborhoods with the homes closest to the runway getting the worst of the noise.
Cars don't derive their propulsion by pushing air. Airboats are a closer comparison. They normally are powered by a V8 and are extremely loud. Not just from the unmuffled engine but also from the big ass fan that's attached to it.
I believe the big difference is that electric engines are wildly more reliable than piston engines. That allows less maintenance and shorter turnaround times, so it spends more time in the air than turboprops can.
That's probably true, but I don't think we have much experience with electric motors operating in high altitude at the power levels required by planes. It'll be some time before we have as good an understanding as we have with jet engines, turboprops and piston engines. Remember these engines will cycle through extreme temperature changes every day of their active lives.
Yes, they will be quite hot, just below the Curie point of the magnets, during flights, especially during take-offs, and ambient temperature when on land (which can easily be freezing at winter time).
I wonder how much different it's from terrestrial electric motors that are not constantly powered. They don't have the weight limitations, though.
One application for super capacitors that I always think about is electric planes. These small planes represent a drop in the total fuel consumption of air travel. The majority of it is consumed by commercial passenger airlines and shipping.
The second most important metric batteries have to meet is charging time. The lower the time the plane spends on the ground, the better return on investment. Having to wait for a plane to charge is not ideal for airlines. A super capacitor power bank can be charged much faster than a lithium ion battery bank.
The third is power delivery. I haven't calculated the power required to take off, but given the usual 30s "sprint" (not sure what the technical term is here) to take off the rest can be calculated from that. I haven't calculated it yet, but lithium battery packs usually are restricted to Capacity == Power i.e. 1Wh == 1W. With super capacitors that ratio is sometimes 100x that
The downside to super capacitors is even the best ones created so far (in research not commercial) are the graphene ones that loose their power in 12h.
This isn't a deal breaker but it does probably limit a capacitor powered electric plane to 6hour rides max
Hope someone else finds this rambling interesting :)
I can imagine a hybrid where a super capacitor is used as a booster at takeoff, when power consumption is 5-10 times higher than in horizontal flight. It does not need to keep the charge for a long time, and can be charged right before the flight. It will eliminate many thermal issues with lithium cells at high currents.
Yes but the limit that I talked about takes into consideration parallel charging. The limit is for each individual cell, so even if each individual cell is charged in parallel it would still take an hour at least to charge
You could charge the lithium batteries faster but that negatively impacts the lifetime of the battery
It seems that electric plane will have one big pain point in adoption for larger passenger craft: the time to refuel/recharge the batteries. Gate dwell time is one of the major costs for an airline both in terms of lost revenue and in fees charged by the airport itself.
These planes are hybrids - they use a turbine to charge batteries and power the EDF engines. I suppose the batteries are used for take off and cruise flight is mostly powered by the turbine (that doesn't have to be powerful enough for takeoff). Landing, again, can be purely electric.
It could, but it will complicate the design a bit since you have to have very easy and quick access to the battery which means a new piece of machinery on the ground to swap the battery and exterior access hatches.
The next century of personal transportation will be autonomous electric cars for short distances, autonomous regional rail for medium within-density transport (e.g.. interborough or within-the-Bay-Area distances), autonomous electric aircraft for cross-density transport(e.g. New York to the Hamptons or Cupertino to Napa) and cheap windowless airplanes for long distance. The unique aspect of this vision is the reduced role for public transit outside intracity subway and regional commuter rail. Autonomous cars and planes seem to increase road efficiency in a manner that competes effectively with rail for density-crossing transport.
And this vision is terrible for energy efficiency and space efficiency. Look at developing countries, there's often a large dependence on taxis and three-wheelers, due to the low labor costs the economics are similar to self driving cars in industrialized countries (some scholars predict the cost of cleaning of shared autonomous cars will be substantial, which may make it similar to the drivers cost in developing countries). Meanwhile, the capacity increases are likely oversold, as you can see in developing countries that have poor transit: total grid lock.
Your "Futurama" vision of car-centric cities is old, tired, and not working, throwing the words 'electric' and 'autonomuous' in there isn't gonna chance much.
The last study I saw on the topic estimated most urban travel could be accomplished with 11% of the existing fleet if cars drove constantly. So not only do you return all the parking space to the economy, but you also increase roads' capacity by something around tenfold. Throwing "autonomous" in changes the capacity tradeoffs and throwing "electric" in makes more cars more pleasant, from both an emissions as well as noise perspective.
11% seems incredibly unlikely. How is a single car going to get 10ppl (on average!) to work during rush hour. Add in destroying transit, and the kind of sprawl that "Futurama" fantasies tend to come with, and I doubt this is going to work. Many roads are already fully congested during rush, where could a 10x capacity increase possibly come from...
The last studies I heard about talked about reducing the required vehicle Fleet by 3 vor 4, while actually _increasing_ VMT.
> where could a 10x capacity increase possibly come from
Eliminating street-side parking single-handedly gives you 2x to 3x on side streets. Tighter packing and better routing does a lot of the rest. You can't do the latter until a zone goes 100% autonomous, which is unrealistic for e.g. Dallas but very much so for downtown Manhattan.
> Add in destroying transit
Nobody said anything about destroying transit. Earlier, I explicitly mentioned rail for within-density transit.
It you turn parking lanes into driving lanes, you're not increasing the capacity of the existing infrastructure, but creating much more driving infrastructure. It also won't 'return' parking to the economy.
Consider the 'staying quality' of a <parking lane+driving lane+parking lane> residential street turned into a 3-lane thoroughfare. That's exactly the sort of dystopia that new urbanists and sustainable mobility advocates are warning about.
Blended-wing bodies [1] are very efficient. So you get a bigger jet that's cheaper to fly. Downside: some seats will be on the inside. Moreover, windows are a huge stress point on air frames. A windowless craft is cheaper to maintain.
If there's one preference travelers show, it's that for cheaper tickets. A windowless blended-wing aircraft delivers on that.
One of the biggest issues with further adoption of Blended Wind Body aircraft is that current FAA regs require demonstration that deplaning the aircraft in an emergency is possible at full seating capacity, including crewmembers, in 90 seconds or less [1], although studies and simulations have been done that continue to evaluate this [2]
BWB with their pax on the inside, make this very challenging.
So all the revolutions are schedualed to happen at once. Electric vehicles, planes. Autonomous vehicles. Abandonment of private vehicles. All at once? I think the commitee is overreaching a little. Did i miss a meeting?
We had Internet, Mobile phones and GPS becoming widely adopted in the same decade, I don't see why that wouldn't be possible.
That being said I don't think they will land and be adopted widely at the same time. I would see electric cars first, then more renewable energy, then self driving cars, then electric planes, all across two decades or so.
Electric planes (at the size of boeing/airbus) are a long way away. In terms of energy density, batteries will have to be far better than diesel fuel if they want to succeed in big aviation. It has to be better because, unlike with fuels, a battery-power aircraft does not get lighter as it empties the tanks, which also means the frame has to be stronger to land at the takeoff weight. This becomes more and more an issue as you scale to larger aircraft. Lithium-ion batteries will never get to this point. Short of some new breakthrough technology, I don't see it becoming a thing in our lifetimes.
The plane being proposed is not purely electrical: it's powered by a turbine, think of a big APU, that powers the EDFs and changes the batteries, which don't need to be large enough to power the whole flight.
Time on the ground = time not being spent on hauling paying passengers.
This is the key problem with battery-powered electric vehicles and why fuel cells make so much more sense that battery packs. Fuel cells are a much "harder" technology to get correct and the tech is very difficult to get correct.
