6 ms·

It's a crowded market and they are targeting planes that can replace jets for medium and longer distance. Which at least short term won't be electric. That woul

It's a crowded market and they are targeting planes that can replace jets for medium and longer distance. Which at least short term won't be electric. That would require breakthroughs in fuel cells that I think they are starting to conclude are a combination of expensive and impractical. And there's the whole notion that green hydrogen is more of a promise than a reality right now. Battery electric makes a lot of sense for smaller planes and distances. But that's a very dynamic market with a lot of players and not a lot of clear added value for Rolls-Royce. Also, it's very different from their current market which is basically focused on jet engines for big planes. That stuff is just way out of their comfort zone. IMHO, the commuter plane market will change quite dramatically in the next decade. Basically battery electric is not a drop in replacement for those planes. But instead that market will start shifting to much simpler and smaller planes that are dirt cheap to manufacture and operate. Basically the main cost is the battery and the maintenance. Add autonomous flight or at least vastly simpler operations to the mix and pilot cost goes down as well. That enables flying with much more but smaller planes. Which in turn enables flying to and from much smaller airfields closer to where people want to go. With vtol, potentially even inside cities. Long term commuter jets (with fuel cells or sustainable fuel) won't be able to compete on cost for short hops.

graphe 3y ago
Where do you think the term autopilot came from? ;) Smaller planes means more crowded airspace. I bet the permits will be the biggest obstacle. How would you price these? It would be hilarious if small planes took over instead of high speed rail. I could see cheaper helicopters being popular.
- unglaublich 3y ago
  Oh, wouldn't it be hi· lar· i· ous to see 250 gCO2eq/km/person domestic flights overtake 4 gCO2eq/km/person rail... and the numbers for helicopters are even worse! https://ourworldindata.org/travel-carbon-footprint https://ourworldindata.org/travel-carbon-footprint
  - graphe 3y ago
    I'm wondering if helicopter pads make a big difference or if they're taking off from the ground. Sky bridges, underground walkways, or trams could be used in highly congested areas, but the US lacks long term planning, and can't into 3D space.
- aeternum 3y ago
  Airspace is used very inefficiently right now. With today's tech it's ridiculous we're still using primarily human vision for collision avoidance in most conditions, and in instrument conditions, spacing is typically 3nm. If you mostly have maneuverable VTOLs or even with more automated systems on traditional planes, you could safely bring down that spacing considerably. Imagine if we required cars on the highway to keep even a 1 mile spacing/following distance and then complained about highway congestion.
  - Nzen 3y ago
    Perhaps the distance requirements reflect airplane wakes, rather than collision avoidance [0]. Analagously, I don't like to follow cars closely on wet roads, given the plume of side spray [1]. [0] https://www.faa.gov/air_traffic/publications/atpubs/aim_html/chap7_section_4.html https://www.faa.gov/air_traffic/publications/atpubs/aim_html... subsection 7-4-9, titled Air Traffic Wake Turbulence Separations [1] https://www.youtube.com/watch?v=C-1-btUcMiA https://www.youtube.com/watch?v=C-1-btUcMiA 20 seconds long
    - aeternum 3y ago
      Wake turbulence is mostly a concern for small planes following large planes. In the right conditions (pilots visually maintaining separation), planes do get quite close and at many airports like SFO, it's the only way to accommodate all the scheduled flights: https://www.youtube.com/watch?v=NLCcxCdrL5w https://www.youtube.com/watch?v=NLCcxCdrL5w
  - mminer237 3y ago
    > spacing is typically 3nm For anyone else not that familiar with aviation and very confused, this means three nautical miles—about 3½ regular miles, not that it's smaller than a transistor fin.
  - jjav 3y ago
    > Imagine if we required cars on the highway to keep even a 1 mile spacing Distance doesn't matter, what matters is time. Planes traveling at say 500 knots obviously need more safety margin distance than cars traveling an order of magnitude slower.
- vlovich123 3y ago
  I mean learning to fly a plane is about the price of a car and the rental price is ~200/hr. You can use it really for recreational purposes only because it can only transit between certain places & it seats 2 people. That really puts it into the expensive hobby category. If you had autopilot remove the need to learn to fly the thing and provide for increased density of air space + figure out how to let aviation vehicles takeoff and land more flexibly, it would become the commute option of choice for more people (it would still be quite pricy due to fuel costs but you’d see way more of them)
bluGill 3y ago
I think you are too optimistic. While we can do everything you state, I don't think there is enough demand. Most people don't want to be a pilot these days, the exceptions are not enough to support all the R&D needed to get there. Likewise, the other niches where people use airplanes for short flights are not large enough to support the R&D needed to get there. So small flights will be stuck with 1960s airplanes they keep rebuilding, with a few small manufactures doing small refinements on designs that are decades old, as a major redesign is just too expensive. Once in a while some rich person will finance a new airplane, but it will always be a money losing investment and so only flying enthusiasts will spend that money.
- civilitty 3y ago
  Agreed, GP is way too optimistic. Airplane manufacturing peaked in the late 1970s with over 18,000 planes manufactured a year. These days the numbers are under 3,000 planes a year! Switching to a new power source isn't going to change the fundamental economics of airplane manufacturing. There just isn't enough demand to reach any kind of scale and it's not the gas prices - manufacturing collapsed to its lowest point in the early 1990s before gas prices went out of control.
- tivert 3y ago
  > I think you are too optimistic. While we can do everything you state, I don't think there is enough demand. Most people don't want to be a pilot these days, the exceptions are not enough to support all the R&D needed to get there. IIRC, there isn't even enough demand there to switch away from leaded fuel.
  - S201 3y ago
    It's not that there's not a demand for unleaded avgas, I'd say most GA pilots are ambivalent to leaded vs. unleaded fuel; they just want whatever makes the prop spin. The issues with the unleaded avgas rollout are purely bureaucratic. The FAA has been dragging its feet for literally decades to get it done. Even when we have fuels like G100UL approved which is a drop-in replacement for ~80% of the GA fleet, it still takes forever to get across the finish line.
nradov 3y ago
Lower pilot costs are unlikely any time soon. The FAA might eventually allow single pilot operation for some cargo flights, but it's just not going to happen for passenger airliners larger than an air taxi. The routine flying operations can be automated to an extent, but nothing on the horizon will allow for automated failure management. Two experienced pilots are the bare minimum to handle the workload of major in-flight emergencies.
guidedlight 3y ago
Nobody is going to be flying to Europe or Australia on a smaller plane. Maybe SAF provides an answer for these flights, but it would likely be prohibitively expensive. The solution likely is mandating carbon offset payments for these passengers.
- advisedwang 3y ago
  > Nobody is going to be flying to Europe or Australia on a smaller plane. We've already seen a shift to smaller planes. Fleets are replacing 747s with 787s, and the A380 is already out of production.
  - freedom-fries 3y ago
    787 isn't a small plane! 787 is just 11% smaller by wingspan and just 3% smaller range than long-range 747. In large part, 747 and 380 went away because they were fuel-inefficient 4-engine planes, not because airlines wanted to fly tiny planes between LA and NY.
    - anakaine 3y ago
      Its definitely smaller in terms of capacity. Different seating configurations aside, notionally the 747 could seat 366 passengers whilst the 787 can seat 242.
      - notahacker 3y ago
        Your notional figures are low for both aircraft. You can get 330 passengers in the 787-10 in a reasonably spacious two class configuration, or cram another hundred more in a single class configuration. Either way the difference in cabin space is essentially irrelevant to arguments about "smaller planes" in the context of suitability for battery power. We're still talking about widebodies carrying well over 200 passengers which would be entirely unsuitable for battery powered replacements, and the 787 is larger than many of the other widebodies it's replacing.
    - 3y ago
fwungy 3y ago
Fuel weight for liquid fuel at start of flight: 10x Fuel weight for liquid fuel at end of flight: 3x Fuel weight for battery at start of flight: 100x Fuel weight for battery at end of flight: 100x Batteries are not a great idea for a planes primary energy source. Liquid fueled planes get lighter and more efficient as they fly, a battery plane starts with a much larger and heavier fuel load and carries it the whole trip. Not only that, battery costs a lot more than fuel tanks.
- Johnny555 3y ago
  >Liquid fueled planes get lighter and more efficient as they fly, a battery plane starts with a much larger and heavier fuel load and carries it the whole trip I saw a concept once that had the plane drop the big battery after takeoff (maybe after reaching cruising altitude too) and let the battery fly back to the airport autonomously. Then it doesn't have to carry that dead weight for the entire trip. But, just like the promise of extended range batteries you could tow behind your EV for long trips, it's probably not real-world feasible.
  - raverbashing 3y ago
    Something like a carrier launch catapult, I think, would make more sense to be honest
    - Johnny555 3y ago
      Does the rollout from 0 - 200mph takeoff speed really use the bulk of the takeoff energy? I figured most of the energy went to climbing 6 miles in altitude.
      - dredmorbius 3y ago
        I believe you're correct in this. An aircraft carrier's catapult isn't about getting an aircraft to altitude, but about getting it to flight speed, on the attenuated runway of a carrier deck. (Landing and arrestor cables are the equivalent problem in reverse.) That said, a divide-and-conquer approach to reducing overall aircraft energy use might go some way to making electrically-powered flight ... at least more feasible, for larger payloads / passenger capacities, and distances, than is now conceived. This includes ground taxiing (jet engines are quite inefficient at low speeds) via tugs, some form of take-off assist, jettisonable battery packs (after take-off and climb phases), general lightweighting of the airframe itself (already a major area of both research and accomplishment for electric aircraft), and automation and removing requirements for onboard pilots and flight attendants (the more paying bodies the more effective the business proposition). There's possibly some room for optimisation of engine and airframe efficiencies, routing, and traffic control, and possibly some gains by hybrid designs (fuel + battery with electric drives, say). As a whole though I suspect electric aircraft have been oversold, and that aviation as a whole will see reduced availability and usage in future.
meindnoch 3y ago
And self-driving cars should be here by 2015! Sorry, but the 2010s called, and want their naïve techbro optimism back.
I_Am_Nous 3y ago
I really wonder if a mixed approach isn't best. Make the planes like trains, where the propellors would be electric motors, while there's a generator in the fuselage running on AVFUEL it was already going to burn in a jet engine. Reduced complexity, centralized weight, possibly modular system where bigger loads can be possible with a generator swap for more output and propellor swap for more bite. I'm sure some level of batteries would be required for safety if the generator dies mid flight, but a load of emergency batteries is much smaller than a load of main fuel cell batteries.
- Ekaros 3y ago
  Turboprops that is turbine driven propellers(also turbines produce some trust) are very efficient. Better than generators you could use. And they are also simple for power produced. Only down side really is that the optimal speed is quite a bit lower than jets.
- nradov 3y ago
  That type of series hybrid architecture works well in locomotives where weight isn't much of an issue but it's totally unsuitable for aircraft. The necessary generator hardware is too heavy, and it loses a lot of efficiency compared to a direct mechanical connection. Some sort of parallel hybrid architecture is more likely for short to medium haul airliners. They will use somewhat smaller turbine engines for cruise, augmented by battery powered electric motors for takeoff (or emergencies).
emodendroket 3y ago
I feel like if we’re serious about decarbonization it’s likely that the solution involves fewer people flying, particularly on overland routes.
laurencerowe 3y ago
When I worked in London a lot of weekly commuters flew rather than to the train from Scotland, or even Manchester given the absurd peak time train fares even though flying was usually slower on that route. These commuter trips definitely won’t be replaced with small planes since capacity at London airports is too constrained.
- jillesvangurp 3y ago
  You assume that you would need big airports. The UK is full of smaller airports. And more could be built if there is demand. Noise and pollution are much less of a factor with electrical planes. And with vtols, any open space or roof potentially qualifies as a spot where you can land. Most of the constraints with current aviation don't really apply here.
  - vidarh 3y ago
    Lilium is one of the companies that aimed for the "air taxi" market and touted any space or roof. They've since both increased the size of their planes a bit and dropped the idea in favour of flying between dedicated sites and backed away from the "air taxi" vision towards flying between small regional sites. I think the issue being that even if you get to the noise level needed, convincing regulators about the safety will take a long time. I think there will be market, and it might also very well make expansion of existing airports less controversial if it is for less noisy tiny electric VTOL planes, but I think at best in the short to medium term they'll also be able to fly to helipads. Getting additional locations approved will probably happen, but I suspect it will be a very slow, arduous process at first, which will only accelerate once people have both spent significant time near a landing site and not felt inconvenienced enough to oppose one elsewhere and flown in these planes and felt them convenient enough to want them nearby.
  - laurencerowe 3y ago
    The flight is only part of the journey. People mostly want to get to city centres where the offices are. Small airports just don't have the transport links to get into the centre. It's bad enough trying to get to Stansted Airport on its slow train and that has 27M annual passengers.

graphe 3y ago

Where do you think the term autopilot came from? ;) Smaller planes means more crowded airspace. I bet the permits will be the biggest obstacle. How would you price these? It would be hilarious if small planes took over instead of high speed rail. I could see cheaper helicopters being popular.

unglaublich 3y ago
Oh, wouldn't it be hi· lar· i· ous to see 250 gCO2eq/km/person domestic flights overtake 4 gCO2eq/km/person rail... and the numbers for helicopters are even worse! https://ourworldindata.org/travel-carbon-footprint https://ourworldindata.org/travel-carbon-footprint
- graphe 3y ago
  I'm wondering if helicopter pads make a big difference or if they're taking off from the ground. Sky bridges, underground walkways, or trams could be used in highly congested areas, but the US lacks long term planning, and can't into 3D space.
aeternum 3y ago
Airspace is used very inefficiently right now. With today's tech it's ridiculous we're still using primarily human vision for collision avoidance in most conditions, and in instrument conditions, spacing is typically 3nm. If you mostly have maneuverable VTOLs or even with more automated systems on traditional planes, you could safely bring down that spacing considerably. Imagine if we required cars on the highway to keep even a 1 mile spacing/following distance and then complained about highway congestion.
- Nzen 3y ago
  Perhaps the distance requirements reflect airplane wakes, rather than collision avoidance [0]. Analagously, I don't like to follow cars closely on wet roads, given the plume of side spray [1]. [0] https://www.faa.gov/air_traffic/publications/atpubs/aim_html/chap7_section_4.html https://www.faa.gov/air_traffic/publications/atpubs/aim_html... subsection 7-4-9, titled Air Traffic Wake Turbulence Separations [1] https://www.youtube.com/watch?v=C-1-btUcMiA https://www.youtube.com/watch?v=C-1-btUcMiA 20 seconds long
  - aeternum 3y ago
    Wake turbulence is mostly a concern for small planes following large planes. In the right conditions (pilots visually maintaining separation), planes do get quite close and at many airports like SFO, it's the only way to accommodate all the scheduled flights: https://www.youtube.com/watch?v=NLCcxCdrL5w https://www.youtube.com/watch?v=NLCcxCdrL5w
- mminer237 3y ago
  > spacing is typically 3nm For anyone else not that familiar with aviation and very confused, this means three nautical miles—about 3½ regular miles, not that it's smaller than a transistor fin.
- jjav 3y ago
  > Imagine if we required cars on the highway to keep even a 1 mile spacing Distance doesn't matter, what matters is time. Planes traveling at say 500 knots obviously need more safety margin distance than cars traveling an order of magnitude slower.
vlovich123 3y ago
I mean learning to fly a plane is about the price of a car and the rental price is ~200/hr. You can use it really for recreational purposes only because it can only transit between certain places & it seats 2 people. That really puts it into the expensive hobby category. If you had autopilot remove the need to learn to fly the thing and provide for increased density of air space + figure out how to let aviation vehicles takeoff and land more flexibly, it would become the commute option of choice for more people (it would still be quite pricy due to fuel costs but you’d see way more of them)

bluGill 3y ago

I think you are too optimistic. While we can do everything you state, I don't think there is enough demand. Most people don't want to be a pilot these days, the exceptions are not enough to support all the R&D needed to get there. Likewise, the other niches where people use airplanes for short flights are not large enough to support the R&D needed to get there. So small flights will be stuck with 1960s airplanes they keep rebuilding, with a few small manufactures doing small refinements on designs that are decades old, as a major redesign is just too expensive. Once in a while some rich person will finance a new airplane, but it will always be a money losing investment and so only flying enthusiasts will spend that money.

civilitty 3y ago
Agreed, GP is way too optimistic. Airplane manufacturing peaked in the late 1970s with over 18,000 planes manufactured a year. These days the numbers are under 3,000 planes a year! Switching to a new power source isn't going to change the fundamental economics of airplane manufacturing. There just isn't enough demand to reach any kind of scale and it's not the gas prices - manufacturing collapsed to its lowest point in the early 1990s before gas prices went out of control.
tivert 3y ago
> I think you are too optimistic. While we can do everything you state, I don't think there is enough demand. Most people don't want to be a pilot these days, the exceptions are not enough to support all the R&D needed to get there. IIRC, there isn't even enough demand there to switch away from leaded fuel.
- S201 3y ago
  It's not that there's not a demand for unleaded avgas, I'd say most GA pilots are ambivalent to leaded vs. unleaded fuel; they just want whatever makes the prop spin. The issues with the unleaded avgas rollout are purely bureaucratic. The FAA has been dragging its feet for literally decades to get it done. Even when we have fuels like G100UL approved which is a drop-in replacement for ~80% of the GA fleet, it still takes forever to get across the finish line.

nradov 3y ago

Lower pilot costs are unlikely any time soon. The FAA might eventually allow single pilot operation for some cargo flights, but it's just not going to happen for passenger airliners larger than an air taxi. The routine flying operations can be automated to an extent, but nothing on the horizon will allow for automated failure management. Two experienced pilots are the bare minimum to handle the workload of major in-flight emergencies.

guidedlight 3y ago

Nobody is going to be flying to Europe or Australia on a smaller plane. Maybe SAF provides an answer for these flights, but it would likely be prohibitively expensive. The solution likely is mandating carbon offset payments for these passengers.

advisedwang 3y ago
> Nobody is going to be flying to Europe or Australia on a smaller plane. We've already seen a shift to smaller planes. Fleets are replacing 747s with 787s, and the A380 is already out of production.
- freedom-fries 3y ago
  787 isn't a small plane! 787 is just 11% smaller by wingspan and just 3% smaller range than long-range 747. In large part, 747 and 380 went away because they were fuel-inefficient 4-engine planes, not because airlines wanted to fly tiny planes between LA and NY.
  - anakaine 3y ago
    Its definitely smaller in terms of capacity. Different seating configurations aside, notionally the 747 could seat 366 passengers whilst the 787 can seat 242.
    - notahacker 3y ago
      Your notional figures are low for both aircraft. You can get 330 passengers in the 787-10 in a reasonably spacious two class configuration, or cram another hundred more in a single class configuration. Either way the difference in cabin space is essentially irrelevant to arguments about "smaller planes" in the context of suitability for battery power. We're still talking about widebodies carrying well over 200 passengers which would be entirely unsuitable for battery powered replacements, and the 787 is larger than many of the other widebodies it's replacing.
  - 3y ago

fwungy 3y ago

Fuel weight for liquid fuel at start of flight: 10x Fuel weight for liquid fuel at end of flight: 3x Fuel weight for battery at start of flight: 100x Fuel weight for battery at end of flight: 100x Batteries are not a great idea for a planes primary energy source. Liquid fueled planes get lighter and more efficient as they fly, a battery plane starts with a much larger and heavier fuel load and carries it the whole trip. Not only that, battery costs a lot more than fuel tanks.

Johnny555 3y ago
>Liquid fueled planes get lighter and more efficient as they fly, a battery plane starts with a much larger and heavier fuel load and carries it the whole trip I saw a concept once that had the plane drop the big battery after takeoff (maybe after reaching cruising altitude too) and let the battery fly back to the airport autonomously. Then it doesn't have to carry that dead weight for the entire trip. But, just like the promise of extended range batteries you could tow behind your EV for long trips, it's probably not real-world feasible.
- raverbashing 3y ago
  Something like a carrier launch catapult, I think, would make more sense to be honest
  - Johnny555 3y ago
    Does the rollout from 0 - 200mph takeoff speed really use the bulk of the takeoff energy? I figured most of the energy went to climbing 6 miles in altitude.
    - dredmorbius 3y ago
      I believe you're correct in this. An aircraft carrier's catapult isn't about getting an aircraft to altitude, but about getting it to flight speed, on the attenuated runway of a carrier deck. (Landing and arrestor cables are the equivalent problem in reverse.) That said, a divide-and-conquer approach to reducing overall aircraft energy use might go some way to making electrically-powered flight ... at least more feasible, for larger payloads / passenger capacities, and distances, than is now conceived. This includes ground taxiing (jet engines are quite inefficient at low speeds) via tugs, some form of take-off assist, jettisonable battery packs (after take-off and climb phases), general lightweighting of the airframe itself (already a major area of both research and accomplishment for electric aircraft), and automation and removing requirements for onboard pilots and flight attendants (the more paying bodies the more effective the business proposition). There's possibly some room for optimisation of engine and airframe efficiencies, routing, and traffic control, and possibly some gains by hybrid designs (fuel + battery with electric drives, say). As a whole though I suspect electric aircraft have been oversold, and that aviation as a whole will see reduced availability and usage in future.

meindnoch 3y ago

And self-driving cars should be here by 2015! Sorry, but the 2010s called, and want their naïve techbro optimism back.

I_Am_Nous 3y ago

I really wonder if a mixed approach isn't best. Make the planes like trains, where the propellors would be electric motors, while there's a generator in the fuselage running on AVFUEL it was already going to burn in a jet engine. Reduced complexity, centralized weight, possibly modular system where bigger loads can be possible with a generator swap for more output and propellor swap for more bite. I'm sure some level of batteries would be required for safety if the generator dies mid flight, but a load of emergency batteries is much smaller than a load of main fuel cell batteries.

Ekaros 3y ago
Turboprops that is turbine driven propellers(also turbines produce some trust) are very efficient. Better than generators you could use. And they are also simple for power produced. Only down side really is that the optimal speed is quite a bit lower than jets.
nradov 3y ago
That type of series hybrid architecture works well in locomotives where weight isn't much of an issue but it's totally unsuitable for aircraft. The necessary generator hardware is too heavy, and it loses a lot of efficiency compared to a direct mechanical connection. Some sort of parallel hybrid architecture is more likely for short to medium haul airliners. They will use somewhat smaller turbine engines for cruise, augmented by battery powered electric motors for takeoff (or emergencies).

emodendroket 3y ago

I feel like if we’re serious about decarbonization it’s likely that the solution involves fewer people flying, particularly on overland routes.

laurencerowe 3y ago

When I worked in London a lot of weekly commuters flew rather than to the train from Scotland, or even Manchester given the absurd peak time train fares even though flying was usually slower on that route. These commuter trips definitely won’t be replaced with small planes since capacity at London airports is too constrained.

jillesvangurp 3y ago
You assume that you would need big airports. The UK is full of smaller airports. And more could be built if there is demand. Noise and pollution are much less of a factor with electrical planes. And with vtols, any open space or roof potentially qualifies as a spot where you can land. Most of the constraints with current aviation don't really apply here.
- vidarh 3y ago
  Lilium is one of the companies that aimed for the "air taxi" market and touted any space or roof. They've since both increased the size of their planes a bit and dropped the idea in favour of flying between dedicated sites and backed away from the "air taxi" vision towards flying between small regional sites. I think the issue being that even if you get to the noise level needed, convincing regulators about the safety will take a long time. I think there will be market, and it might also very well make expansion of existing airports less controversial if it is for less noisy tiny electric VTOL planes, but I think at best in the short to medium term they'll also be able to fly to helipads. Getting additional locations approved will probably happen, but I suspect it will be a very slow, arduous process at first, which will only accelerate once people have both spent significant time near a landing site and not felt inconvenienced enough to oppose one elsewhere and flown in these planes and felt them convenient enough to want them nearby.
- laurencerowe 3y ago
  The flight is only part of the journey. People mostly want to get to city centres where the offices are. Small airports just don't have the transport links to get into the centre. It's bad enough trying to get to Stansted Airport on its slow train and that has 27M annual passengers.