4 ms·

370-mile hydrogen-electric seaplane set to clean up island hopping

25 points by peutetre 2y ago

pbmonster 2y ago
I wonder why most of those electric aircraft have so many small propellers. Aerodynamically, having fewer but much larger props would make more sense for efficiency, especially if they're only going 130 knots. But maybe they need the extra lift of the props blowing across almost the entire wing? I wonder if we'll ever see an electric tilt rotor aircraft with huge variable pitch props. Should be much more efficient, but probably also much more mechanically complex...
- detritus 2y ago
  To guess, I'd suggest it might be mostly due to the types of electric motor already produced and available in an appropriate weight and configuraton. Further it might be that redundancy in electric motors might be more of an issue (?) and here, I wonder if they've cracked some added efficiency with having a more consistent flow over the breadth of the wings?
  - pbmonster 2y ago
    I was under the impression that compact 400 hp electric motors (Like in the Plaid Tesla) were available in large numbers. And hopefully, those would be higher reliably at much lower maintenance when compared to a turboprop or a turbojet. And even then, having 4 should be plenty of redundancy.
    - Retric 2y ago
      Tesla engines don’t fit inside a thin wing. Form factor is a huge deal for aerodynamics.
    - serf 2y ago
      it's unlikely that HP is the main thing at play here; an electric motor for a plane would need to be wound or gear-reduced to a point of kV efficiency that fits within a plane's necessities. a 400hp tesla motor is presumably built and wound to be efficient for a car. this isn't that, simply put.
- jauntywundrkind 2y ago
  > Aerodynamically, having fewer but much larger props would make more sense for efficiency, Source? I can think of a lot of flight reasons many small props could be better. You can spin faster while still keeping the tip subsonic. Typically fans have inefficiencies because outter blade moves so much faster than the inner blade & this effect is reduced with smaller blades. If you're looking for a blown wing effect you get much more surface area. Airflow is smoother because prop wash is more dispersed and even. For a while it seemed like many props was the sure way forward. It's definitely less seen now, but for example the Aurora XV-24A LightningStrike, NASA X-57 Maxwell, and GL-10 Greased Lightning seemed like they were setting the way forward. It seemed like technical difficulties that beset the Maxwell team that made them reduce Maxwell to a less ambitious more conventional electric offering. https://www.nasa.gov/stem-content/x-57-electric-airplane/ https://www.nasa.gov/stem-content/x-57-electric-airplane/ https://www.defensenews.com/digital-show-dailies/sas/2017/04/04/electric-drones-aurora-team-behind-vtol-x-plane-focuses-on-hybrid-propulsion/ https://www.defensenews.com/digital-show-dailies/sas/2017/04...
- geor9e 2y ago
  I can think of some possible reasons. Can't kill any ground crew if the prop ends are 8 feet up. Fuel engines get more efficient the bigger you make them, so big propeller aircraft being more efficient isn't necessarily because of the prop size, but rather a side effect of engine size. Electric motors don't gain much efficiency with increased size AFAIK, so they can get away with small motors. Lots of props close to the wing would guide the air well - you don't get that giant vortex of wasted energy. Redundancy - they could lose multiple propellers. That's especially needed since some of these electric aircraft are VTOL and can't glide or autorotate in an emergency. I'm thinking of https://wisk.aero https://wisk.aero . Market constraints - this is a new application so they're relying on other industries for the motors they can pick from.
- serf 2y ago
  interestingly almost all of the original aircraft conceptualizations had a lot of props -- they got simplified due to the realities of drivetrain complexity pre-electrification. redundancy is one reason, weight is another, cost is another. Lower amperage smaller motors require less copper and battery capacity, they're cheaper to produce, they can be placed opportunistically to maximize wing efficiency, and they're quite nearly COTS. bigger props necessitate more power in a singular spot, bigger heavier motor and cooling solutions, so on and so fourth. lots of motors at lower duty cycle can reduce these burdens, and if done right may even be able to get rid of the cooling systems and associated weight entirely.
- darksaints 2y ago
  Having multiple small propellers along the wing is done for lift augmentation. See the X-57 concept plane for an example. If this is anything like the X-57, most of those propellers will feather upon takeoff. Basically, most planes use wings that are much larger and less efficient than they need for cruising, because they need the extra lift for takeoff and landing. By introducing lift augmentation propellers which can augment lift for takeoff/landing, they can use a much smaller wing which has less parasitic drag and results in more efficient flight. https://en.wikipedia.org/wiki/NASA_X-57_Maxwell https://en.wikipedia.org/wiki/NASA_X-57_Maxwell
imglorp 2y ago
> composite airframe to nip corrosion in the bud That's fine, and there's galvanic anodes for the structures that aren't, but it's all the copper wiring and connections that will be a practical problem.
ChrisMarshallNY 2y ago
> vegan leather I've always found this branding a bit weird, but I'm weird, as well, so there's that... I sincerely wish them luck. I don't know that much about hydrogen fuel cells, but they seem to be promising. Not exactly sure why they don't get much more love. Maybe there are issues with hydrogen production, so it's not really all that "clean."
- JojoFatsani 2y ago
  It just means “vinyl” but it sounds more upscale than it is
- jofer 2y ago
  There are lots of different types of hydrogen production, but many of them are "clean" (or at least as clean as solar, anyway). The main issue with hydrogen is storage and transport. It's not an unsolvable problem, by any means, but it's significantly more difficult to safely store and transport than liquid hydrocarbons, at any rate. Hydrogen requires significant investments in infrastructure around it which mostly haven't been made yet.
  - bryanlarsen 2y ago
    Many methods are clean, but currently 95% of hydrogen production is not clean.
    - jofer 2y ago
      That's largely because it's a byproduct of common hydrocarbon refining techniques. It's a bit silly to throw that away once it's produced.
- geor9e 2y ago
  What's the less weird way to say vegan leather? I tried, but it was got weirder.
  - Out_of_Characte 2y ago
isthispermanent 2y ago
The fuel cell tech isn’t the problem, it’s that there is no hydrogen gas infrastructure. And there’s certainly no robust H supply that doesn’t include fossil fuel to create the H gas. Hydrogen fuel cells are just this constant pie in the sky thing. Stop making them and go solve the H infra problem, that’s the barrier.
- kurthr 2y ago
  Hydrogen is a terrible battery. Best case conversion to H2 is ~80%, while best case fuel cell efficiency is ~50%. That's 40% round trip while most batteries can do 90%. That ignores losses due to leakage, but those are only a couple of percent. Also, ignore the hazards, but the cost of building safe low leakage infrastructure might exceed the cost of batteries and solar/wind to produce power. You're probably better off making H2 dynamically where you need it and just sending electrons or storing them locally in safe batteries.
  - dmitrygr 2y ago
    People say stuff like this a lot, my guess is that you don’t fly airplanes. The fact that the airplane gets lighter as it burns fuel is kind of important and is used to simplify airplane design a lot (check out the difference between MTOW and MLW of a 777) . Batteries don’t get lighter.
    - kurthr 2y ago
      To be polite, my guess is you've never tried storing dense hydrogen or running high power fuel cells. The solutions are large, heavy, expensive, and not very safe in enclosed areas. The solutions under consideration involve batteries for backup.
      - dmitrygr 2y ago
        I never said H2 is the solution (I do not believe so). I just said that batteries are NOT.
rkagerer 2y ago
composite airframe to nip corrosion in the bud Aren't there still all kinds of fasteners, brackets, sensors, etc? How much of that is proper 316 stainless vs. materials that will have the traditional corrosion problems? What other mitigations are made on seaplanes?
supernova87a 2y ago
I am no expert in hydrogen fuel cells and am interested to know. Do fuel cells deliver enough instantaneous power that batteries do, for the weight of all the associated equipment? Certainly the power density of the fuel is high, but given all the membranes, plates, etc. (all the "bubbling chemistry that has to happen"), how is the power delivery per hardware weight? Sometimes I imagine that exploding hydrogen in an engine (if it were possible) would be more power dense than sending it through fuel cells. (as I said I'm clearly no expert about fuel cells) And separate minor point, while it's pointed out as a novelty, I somehow doubt the composite construction is really targeted at anti-corrosion (I mean it might contribute a little on this front I guess). Corrosion issues in seaplanes are well understood for 50+ years, right? It's for the weight savings mostly.
- danans 2y ago
  > Do fuel cells deliver enough instantaneous power that batteries do, for the weight of all the associated equipment? I don't know about planes, but fuel cell cars have batteries, although smaller ones that EVs, which are actually used for the motors. HFC cars are basically EVs plus the hydrogen system.
- practicemaths 2y ago
  Without having specific numbers in front of me, yes fuel cells are delivering comparable power as batteries. Plus the hydrogen is lighter than batteries. Combusting may save on some of the complexity fuel cells but you are losing efficiency in heat losses, both from the act of combusting and with gears that deliver the power to your wheels or propeller.
  - darksaints 2y ago
    They can produce the same levels of continuous power, but their spin up (think throttle response) is drastically slower. FC Cars definitely need a battery or supercapacitor to handle instantaneous power needs. For planes and ships, that responsiveness is not needed.
- darksaints 2y ago
deleted 2y ago
[deleted]
more_corn 2y ago
Hydrogen comes from petroleum. It’s just oil with extra (cryogenic) steps in the fuel supply chain. Nothing will be “cleaned up” with hydrogen.

25 points by peutetre 2y ago

I wonder why most of those electric aircraft have so many small propellers. Aerodynamically, having fewer but much larger props would make more sense for efficiency, especially if they're only going 130 knots. But maybe they need the extra lift of the props blowing across almost the entire wing? I wonder if we'll ever see an electric tilt rotor aircraft with huge variable pitch props. Should be much more efficient, but probably also much more mechanically complex...

detritus 2y ago
To guess, I'd suggest it might be mostly due to the types of electric motor already produced and available in an appropriate weight and configuraton. Further it might be that redundancy in electric motors might be more of an issue (?) and here, I wonder if they've cracked some added efficiency with having a more consistent flow over the breadth of the wings?
- pbmonster 2y ago
  I was under the impression that compact 400 hp electric motors (Like in the Plaid Tesla) were available in large numbers. And hopefully, those would be higher reliably at much lower maintenance when compared to a turboprop or a turbojet. And even then, having 4 should be plenty of redundancy.
  - Retric 2y ago
    Tesla engines don’t fit inside a thin wing. Form factor is a huge deal for aerodynamics.
  - serf 2y ago
    it's unlikely that HP is the main thing at play here; an electric motor for a plane would need to be wound or gear-reduced to a point of kV efficiency that fits within a plane's necessities. a 400hp tesla motor is presumably built and wound to be efficient for a car. this isn't that, simply put.
jauntywundrkind 2y ago
> Aerodynamically, having fewer but much larger props would make more sense for efficiency, Source? I can think of a lot of flight reasons many small props could be better. You can spin faster while still keeping the tip subsonic. Typically fans have inefficiencies because outter blade moves so much faster than the inner blade & this effect is reduced with smaller blades. If you're looking for a blown wing effect you get much more surface area. Airflow is smoother because prop wash is more dispersed and even. For a while it seemed like many props was the sure way forward. It's definitely less seen now, but for example the Aurora XV-24A LightningStrike, NASA X-57 Maxwell, and GL-10 Greased Lightning seemed like they were setting the way forward. It seemed like technical difficulties that beset the Maxwell team that made them reduce Maxwell to a less ambitious more conventional electric offering. https://www.nasa.gov/stem-content/x-57-electric-airplane/ https://www.nasa.gov/stem-content/x-57-electric-airplane/ https://www.defensenews.com/digital-show-dailies/sas/2017/04/04/electric-drones-aurora-team-behind-vtol-x-plane-focuses-on-hybrid-propulsion/ https://www.defensenews.com/digital-show-dailies/sas/2017/04...
geor9e 2y ago
I can think of some possible reasons. Can't kill any ground crew if the prop ends are 8 feet up. Fuel engines get more efficient the bigger you make them, so big propeller aircraft being more efficient isn't necessarily because of the prop size, but rather a side effect of engine size. Electric motors don't gain much efficiency with increased size AFAIK, so they can get away with small motors. Lots of props close to the wing would guide the air well - you don't get that giant vortex of wasted energy. Redundancy - they could lose multiple propellers. That's especially needed since some of these electric aircraft are VTOL and can't glide or autorotate in an emergency. I'm thinking of https://wisk.aero https://wisk.aero . Market constraints - this is a new application so they're relying on other industries for the motors they can pick from.
serf 2y ago
interestingly almost all of the original aircraft conceptualizations had a lot of props -- they got simplified due to the realities of drivetrain complexity pre-electrification. redundancy is one reason, weight is another, cost is another. Lower amperage smaller motors require less copper and battery capacity, they're cheaper to produce, they can be placed opportunistically to maximize wing efficiency, and they're quite nearly COTS. bigger props necessitate more power in a singular spot, bigger heavier motor and cooling solutions, so on and so fourth. lots of motors at lower duty cycle can reduce these burdens, and if done right may even be able to get rid of the cooling systems and associated weight entirely.
darksaints 2y ago
Having multiple small propellers along the wing is done for lift augmentation. See the X-57 concept plane for an example. If this is anything like the X-57, most of those propellers will feather upon takeoff. Basically, most planes use wings that are much larger and less efficient than they need for cruising, because they need the extra lift for takeoff and landing. By introducing lift augmentation propellers which can augment lift for takeoff/landing, they can use a much smaller wing which has less parasitic drag and results in more efficient flight. https://en.wikipedia.org/wiki/NASA_X-57_Maxwell https://en.wikipedia.org/wiki/NASA_X-57_Maxwell

imglorp 2y ago

> composite airframe to nip corrosion in the bud That's fine, and there's galvanic anodes for the structures that aren't, but it's all the copper wiring and connections that will be a practical problem.

ChrisMarshallNY 2y ago

> vegan leather I've always found this branding a bit weird, but I'm weird, as well, so there's that... I sincerely wish them luck. I don't know that much about hydrogen fuel cells, but they seem to be promising. Not exactly sure why they don't get much more love. Maybe there are issues with hydrogen production, so it's not really all that "clean."

JojoFatsani 2y ago
It just means “vinyl” but it sounds more upscale than it is
jofer 2y ago
There are lots of different types of hydrogen production, but many of them are "clean" (or at least as clean as solar, anyway). The main issue with hydrogen is storage and transport. It's not an unsolvable problem, by any means, but it's significantly more difficult to safely store and transport than liquid hydrocarbons, at any rate. Hydrogen requires significant investments in infrastructure around it which mostly haven't been made yet.
- bryanlarsen 2y ago
  Many methods are clean, but currently 95% of hydrogen production is not clean.
  - jofer 2y ago
    That's largely because it's a byproduct of common hydrocarbon refining techniques. It's a bit silly to throw that away once it's produced.
geor9e 2y ago
What's the less weird way to say vegan leather? I tried, but it was got weirder.
- Out_of_Characte 2y ago

isthispermanent 2y ago

The fuel cell tech isn’t the problem, it’s that there is no hydrogen gas infrastructure. And there’s certainly no robust H supply that doesn’t include fossil fuel to create the H gas. Hydrogen fuel cells are just this constant pie in the sky thing. Stop making them and go solve the H infra problem, that’s the barrier.

kurthr 2y ago
Hydrogen is a terrible battery. Best case conversion to H2 is ~80%, while best case fuel cell efficiency is ~50%. That's 40% round trip while most batteries can do 90%. That ignores losses due to leakage, but those are only a couple of percent. Also, ignore the hazards, but the cost of building safe low leakage infrastructure might exceed the cost of batteries and solar/wind to produce power. You're probably better off making H2 dynamically where you need it and just sending electrons or storing them locally in safe batteries.
- dmitrygr 2y ago
  People say stuff like this a lot, my guess is that you don’t fly airplanes. The fact that the airplane gets lighter as it burns fuel is kind of important and is used to simplify airplane design a lot (check out the difference between MTOW and MLW of a 777) . Batteries don’t get lighter.
  - kurthr 2y ago
    To be polite, my guess is you've never tried storing dense hydrogen or running high power fuel cells. The solutions are large, heavy, expensive, and not very safe in enclosed areas. The solutions under consideration involve batteries for backup.
    - dmitrygr 2y ago
      I never said H2 is the solution (I do not believe so). I just said that batteries are NOT.

rkagerer 2y ago

composite airframe to nip corrosion in the bud Aren't there still all kinds of fasteners, brackets, sensors, etc? How much of that is proper 316 stainless vs. materials that will have the traditional corrosion problems? What other mitigations are made on seaplanes?

supernova87a 2y ago

I am no expert in hydrogen fuel cells and am interested to know. Do fuel cells deliver enough instantaneous power that batteries do, for the weight of all the associated equipment? Certainly the power density of the fuel is high, but given all the membranes, plates, etc. (all the "bubbling chemistry that has to happen"), how is the power delivery per hardware weight? Sometimes I imagine that exploding hydrogen in an engine (if it were possible) would be more power dense than sending it through fuel cells. (as I said I'm clearly no expert about fuel cells) And separate minor point, while it's pointed out as a novelty, I somehow doubt the composite construction is really targeted at anti-corrosion (I mean it might contribute a little on this front I guess). Corrosion issues in seaplanes are well understood for 50+ years, right? It's for the weight savings mostly.

danans 2y ago
> Do fuel cells deliver enough instantaneous power that batteries do, for the weight of all the associated equipment? I don't know about planes, but fuel cell cars have batteries, although smaller ones that EVs, which are actually used for the motors. HFC cars are basically EVs plus the hydrogen system.
practicemaths 2y ago
Without having specific numbers in front of me, yes fuel cells are delivering comparable power as batteries. Plus the hydrogen is lighter than batteries. Combusting may save on some of the complexity fuel cells but you are losing efficiency in heat losses, both from the act of combusting and with gears that deliver the power to your wheels or propeller.
- darksaints 2y ago
  They can produce the same levels of continuous power, but their spin up (think throttle response) is drastically slower. FC Cars definitely need a battery or supercapacitor to handle instantaneous power needs. For planes and ships, that responsiveness is not needed.
darksaints 2y ago

deleted 2y ago

[deleted]

more_corn 2y ago

Hydrogen comes from petroleum. It’s just oil with extra (cryogenic) steps in the fuel supply chain. Nothing will be “cleaned up” with hydrogen.