3 ms·

Maybe I missed it but they didn't delve much into the TAM. "Half of all flights in the world are under 2 hours." Then they give examples of Fjord-town hopping

• gpm 29d ago
  Batteries are rapidly improving (on many metrics, but the relevant one here is increasing in energy density). The range is apparently 125 miles electric, and 500 miles as a hybrid. That's not enough for Melbourne Sydney. Give it a couple doubling-times though (5 years total?) and it will be. Meanwhile aircraft take forever to develop and there should be enough of a market in shorter hall flights to occupy a scaling company in the meantime anyways.
  • ActorNightly 29d ago
    Batteries aren't rapidly improving. Every single battery that has proposed higher energy density also has downsides in max discharge current. We may get at best like 10% improvement over what it is today.
    • enquirewithin 28d ago
      It’s taken thirty years for lithium batteries to double in energy density, and the rate of increase has tapered off recently.
    • aidenn0 28d ago
      That's max discharge current per cell though. You are going to have a lot of cells in a plane like this.
      • ActorNightly 28d ago
        To get high voltage, you need batteries in series, which means all the batteries see the same current. The only way to reduce current is to put batteries in parallel, which for a given voltage doubles the weight of the battery pack. You could go with lower voltage, but that means for a given, power, you need more current, which drops your efficiency.
        • aidenn0 28d ago
          If you are consuming X watts per cell, then each cell will drain by the same amount of current regardless of whether the cells are in series or parallel (or more likely a combination of the two). This is supposed to be able to handle "up to" 2-hour flights, and (for jets at least) takeoff power is about 3x cruise power, so about 1.5 watts per watt-hour of battery, or a 1.5C peak discharge rate. What chemistries are you thinking of that cannot handle this?
          • ActorNightly 24d ago
            You misunderstand what Im saying The full power system for a prop looks like this: you have a battery of a specific voltage, which then runs a motor, which then runs a gearbox, which then turns a prop. The motor and the gearbox can be considered as one unit - an electric motor has two factors, KV(RPM/volt) and KT(torque/amp). The higher the KV, the lower the KT. A high KV motor spins fast, but draws a lot of current for the same torque - putting it through a reduction gearbox turns it into a low KV, high KT motor. Naturally, low KV motors or (low KV setups) are more efficient because they draw less current for a given torque, and the heating power loss varies with current^2. The prop needs to spin at certain RPM for max aerodynamic efficiency. Given the slider for motor/gearbox selection between high KV/low KT and the opposites, you generally want to have as high voltage as possible, so that you can run a low KV/high KT setup, which means that for the given torque, the current is minimal. I.e you have a motor spinning really fast, through a large reduction gear, driving a prop at the necessary speed and torque without much load on the motor. So lets say you determine that you want a certain voltage, which requires a stack of cells in series. The only way to get more capacity is to duplicate that stack and put them in parallel. So your weight becomes quantized by the number of stacks you have in parallel. And the more stacks you have in series, the higher the weight jumps between parallel stacks counts. Subtracting cells from stacks doesn't work well. Lets say you have a single stack of 10 cells 10s1p. If you do something like 8s1p, you lower the output voltage, which means you need to have slightly higher gear ratio to spin the prop at the same efficient rpm, which means you draw more current, which means the extra capacity in the cells doesn't really matter if you are drawing more current.
  • mjcarden 28d ago
    Canberra - Sydney is one of the busiest routes in Australia with Dash 8 and ATR turboprops on high rotation every day. I could see a small electric aircraft working pretty well there, modulo charging times.
    • defrost 28d ago
      > modulo charging times. There's already an Australian electric trucking company trailing plug n'replace heavy battery packs (with a forklift). That allows for fast turnover times while used batteries recharge at terminals.
• xyzelement 29d ago
  I didn't get that far in the video but from where I live (NYC) two hours gets you to a lot of very common travel destinations: Boston, Massachusetts (1h) Washington, D.C. (1h) Philadelphia, Pennsylvania (45m) Baltimore, Maryland (1h) Toronto, Ontario (1h 45m) Montreal, Quebec (1h 30m) Cleveland, Ohio (1h 45m) Pittsburgh, Pennsylvania (1h 15m) Buffalo, New York (1h 10m) Providence, Rhode Island (45m) Portland, Maine (1h 10m) Bermuda (1h 50m) Nantucket, Massachusetts (1h 15m) Martha’s Vineyard, Massachusetts (1h 25m) Ottawa, Ontario (1h 30m) Quebec City, Quebec (1h 45m) Rochester, New York (1h 5m) Syracuse, New York (1h) Manchester, New Hampshire (1h) Bangor, Maine (1h 25m) Burlington, Vermont (1h 10m) Richmond, Virginia (1h 10m) Norfolk, Virginia (1h 15m) Raleigh/Durham, North Carolina (1h 25m) Charlotte, North Carolina (1h 45m) Greensboro, North Carolina (1h 30m) Charleston, South Carolina (2h) Myrtle Beach, South Carolina (1h 45m) Savannah, Georgia (2h) If it gets a little better than current 2 hour flight time then Detroit Chicago and Atlanta are in range - very significant.
  • rossriley 28d ago
    The busiest flight corridor in the world is Singapore to Kuala Lumpur which is only 45 minutes.
• ActorNightly 29d ago
  Electric planes can in theory get longer flights, provided they change the flight profile - you spend a lot of energy going up to higher altitude, and the essentially glide down.
  • enquirewithin 28d ago
    The energy used to achieve altitude is then saved in the descent stage. So that’s not an issue for aircraft, regardless of how they’re powered. This is why every flight you’ve ever been on climbs to cruise altitude as fast as possible. High altitude where the air is less dense is better for speed due to less drag. This is also power source agnostic.
    • ActorNightly 28d ago
      yes, but current battery energy density is nowhere near fuel ATM, and evs operate differently. Gas engines use fuel/hour as a function of RPMS, independant on the load on the engine. EVs use battery juice as a function of the load. When you size a gas engine for a plane, you design around the power needed to takeoff on a given runway, which is fine because in cruise, you will throttle down and use less fuel. When you design an electric vehicle, if you design it the same way, you end up carrying effectively dead battery weight, which also affects power consumption during cruise (you either go faster, or use use more wing, which creates more induced drag). IF you design it for cruise, you end up being horribly inefficient at takeoff. The only 2 solutions are 1. 10 mile long runway where you can take your time accelerating, to reduce the torque requirement on the motor. You would basically limit the current draw and the plane would accelerate slowly, and eventually you get to cruise speed 2. Changing your flight profile, where you get to high altitude ASAP where you can be more efficient,