9 ms·

Electric Planes Usher in the Second Great Age of Aviation

63 points by lelf 11y ago

sokoloff 11y ago
I drive an electric car and fly piston airplanes. I don't see electrics replacing internal combustion in aviation in my flying lifetime. Why? Weight. The specific energy (energy per kg, edited per masklinn) of batteries sadly lags the specific energy of gasoline or kerosene, and the airplane carries that weight for the whole flight for an electric airplane. (My gas airplane gets lighter and lands as much as 1000 pounds lighter than it took off, meaning the landing gear, wing spar attachments, and brakes can all be lighter.) Many airplanes are certified for a ramp, taxi, and takeoff weight higher than their approved landing weight. Electrics will be unable to take advantage of this and must confine their takeoff weight to their landing weight. I love that such rapid progress is being made in automotive, and I'd love to see that adoption increase so we can reserve petro-based fuels for cases where their energy density provides a compelling operational benefit, such as in aviation.
- fit2rule 11y ago
  There is little question that carbon-based flight power is here to stay for quite some time, but that isn't really the point - which is that electric flight is nevertheless a growth industry, and there are some markets where electric flight can make a lot of sense. If all you need to do is go up and fly for 2 hours or so, then an electric plane is a viable contender for the investment - maybe we're not at the tipping point, but we are approaching it, technologically at least, a few knots at a time. It is a worthwhile goal, though. If we can somehow harness the suns' energy to get us around the world instead of using the world itself (and thus screwing it up), then we move closer to the cusp of a more viable long-term civilization. At the moment, every cheap flight to somewhere on a jet plane costs the Earth a great deal of survival potential...
- nacnud 11y ago
  Surely the landing gear, wing spar attachments, and brakes all have to be able to cope with an unexpected turnback and landing with most of the original weight? (not to mention heavy landings in adverse weather conditions)
  - 1stop 11y ago
    I have not idea: But could this be why Planes will often dump fuel for a turn back.
  - hiharryhere 11y ago
    Planes usually fly around for a bit dumping fuel if they need to turn back.
  - yread 11y ago
    No see http://www.caa.co.uk/default.aspx?catid=60&pagetype=90&pageid=822 http://www.caa.co.uk/default.aspx?catid=60&pagetype=90&pagei... or http://www.boeing.com/commercial/aeromagazine/articles/qtr_3_07/article_03_1.html http://www.boeing.com/commercial/aeromagazine/articles/qtr_3... They are only certified to the maximum landing weight which typically is lower than the maximum takeoff weight. When an overweight landing (ie. the weight is higher then maximum landing weight) occurs engineers have to perform a thorough inspection of the plane structure - landing gear, spars, wings, wingbox EDIT: thanks ForHackernews
    - ForHackernews 11y ago
      > the maximum landing weight which typically is larger than the maximum takeoff weight. I assume this was a typo and you mean that the max landing weight is typically less than the max takeoff weight.
    - nacnud 11y ago
      I guess I was thinking more about smaller GA aircraft, but thanks for the detailed reply.
- masklinn 11y ago
  > The energy density of batteries sadly lags the energy density of gasoline or kerosene Nitpick but the energy/mass density is usually called "specific energy" to differentiate it with the more usual energy/volume "energy density". And while a battery's energy density is pretty bad, they pretty universally have a higher density than petroleum fuels and thus even worse specific energy: the best batteries have 2 orders of magnitude worse specific energy than petroleum fuels (Li-Ion or AgZn store 0.46 MJ/kg, kerosene stores 43 MJ/kg)
  - sokoloff 11y ago
    Thanks for that. Yes, I was concerned with "specific energy" (energy per kg, not per m^3).
  - andrewla 11y ago
    > And while a battery's energy density is pretty bad, they pretty universally have a higher density than petroleum fuels and thus even worse specific energy Is there a typo in there? Energy density (MJ/L) for batteries is lower than petroleum fuels by the same order of magnitude as the specific energy.
    - masklinn 11y ago
      While batteries have very energy density compared to petroleum fuels, on average it's much better (compared to petroleum fuels) than their specific energy. Their energy density is 15 ~ 40 times lower than petroleum fuels whereas their energy density is 50 ~ >100 times lower.
- 6stringmerc 11y ago
  I entered the Local Motors and ARPA-E contest for the Lightweight Sedan challenge and proposed a three part method to reduce weight: Revised chassis, bio-composite materials, and a hybrid drivetrain using micro-turbines to produce electricity to power the vehicle. The contest parameters stressed that the proposal should be "research for the next 10 years." So, I cited the efficiency and extremely light-weight of micro turbines to piston engines, and postulated that increasing technology in battery / KERS systems would compliment the real-world application in time. Needless to say, I was ridiculously mad when I saw that the winning entries were 1) an aerodynamic proposal based on an exoskeleton, 2) replacing body panels with a new metallurgy compound, and some other thing that I can't recall right now. None of them really addressed the contest parameters. It basically made me swear off any more Local Motors participation. Anyway, the bright side is that I get to maintain all rights to my entry / materials, so one day, I just might have a chance to develop a concept based on these principles and show ARPA-E and Local Motors what they missed. I guess this is how Ferruccio Lamborghini must have felt at first. Sigh.
  - termain 11y ago
    Exoskeleton? You mean monocoque construction (aka load bearing skin)?
    - 6stringmerc 11y ago
      No, I mean like the chassis components were on the outside of the car, like a bug. That was the crux of their entry, mollified by some talk of aerodynamic efficiency. From what I recall, the rendered images of their concept didn't even have a method of entry for the driver/passengers. No doors. It was...well, frustrating, as my tone probably conveyed. Re: Monocoque - my entry cited that format to give additional strength to the chassis/panels mating. Bio-composites are approaching the tensile strength of carbon fiber, and could potentially be much easier to mass produce and at a lower price point. I thought the implication that in 10 years, with research, such an avenue would be viable. Instead, the second place entry was some proprietary kind of new metal that could be used to replace body panels...that's it. I remember calling that entry a "body kit" because that's what it reminded me of overall.
- fnordfnordfnord 11y ago
  I think we might see gasoline/jet-A over electric airplanes, perhaps with or without battery storage. That would allow a few neat optimizations. You'd have more control over CG. You could have a smaller high efficiency engine that always ran at peak efficiency (or an IC engine with several modes). You could have more control over noise in urban areas. With a battery for peak/boost power, you could have a tiny engine which could supply cruise plus accessory power and use battery-backed boost for takeoff/climb. Engines that are replaceable in a few hours. All kinds of good things could happen. >Many airplanes are certified for a ramp, taxi, and takeoff weight higher than their approved landing weight. Is that common in G/A aircraft? In any case, I'd love to see a tech. revolution in GA powerplants. I've grown tired of having quaint old 1950's era tractor engines be the dominant technology.
  - sokoloff 11y ago
    Once you get past about the 6200#/3000kg MGTOW mark, it's very common to permit takeoff weight to exceed landing weight. I suspect all GA turbojets and most GA turboprops are in this situation. Even the Beech Baron (a light twin) has a 100# (~16 gallons) difference in max takeoff vs max landing weight.
- venomsnake 11y ago
  A fuel cell that carries only hydrogen and harvests oxygen from the atmosphere ... is viable. * *the whole membrane degradation thing excluded
  - trhway 11y ago
    metal-air fuel cells are in many respects even better. And with metal content around 50% they become weight comparable or better than 30% efficient ICE.
    - venomsnake 11y ago
      In that case you have lithium oxide to take care of and you have heavier plane with each second (of course most of the fuel is wasted on lifting the plane, so it may be better)
      - trhway 11y ago
        the electric planes, at least at first, isn't about just swapping ICE for electric. It is about building different planes. The current planes have evolved significantly under the limitations of ICE. The electric planes, at least initially, is about short-hoppers ("flying car" like functionality) where ICE is a no-go because of cost and noise. The electrics are well suited to build STOL and VTOL (multi-copters). With years the electrification can make its way through various hybrid schemes into much more efficient long-haulers.
- coryrc 11y ago
  Electric planes could stop GA poisoning everyone with lead. You could also choose a different fuel. Toy planes (general aviation) are responsible for the majority of lead pollution: www.emagazine.com/earth-talk/lead-in-aviation-fuel
  - sokoloff 11y ago
    The FAA certification process is the largest limiting factor for bringing an unleaded fuel to the market. There are about 9 different formulations of unleaded fuels flying in experimental aircraft right now. I have my own "favorite", but it's unclear when, if ever, that will be available for sale to non-experimental aircraft. The magazine article you reference says that 70% of aircraft could use (a lower octane) unleaded fuel available today. That's true, but paints an incomplete picture. That's 70% by aircraft, not 70% by flight hours or fuel consumed. Cape Air and similar and other turbocharged piston aircraft are the ones that can't use the available unleaded "mogas". Those are also the aircraft that fly the most hours and thereby use the most fuel. Fixing the 172s and Cherokees doesn't move the needle much on TEL emissions. I want to get rid of the lead from my aviation fuel, both for environmental reasons and for practical reasons. (Practically, it's a pain to deal with on the supply chain side, is expensive, there's only one manufacturer of TEL worldwide, it tends to gunk and foul plugs, etc.) The FAA is the regulatory body that is presiding over this, much more than the EPA. End running the FAA to get the EPA to make another "lead is bad" proclamation won't do any good, IMO. My engines can't burn any available and certified unleaded fuel.
    - coryrc 11y ago
      AOPA lobbies to delay unleaded fuel at every opportunity [1] [2] [5]. Unleaded fuel is available now [3], but 10% of owners would have to spend some money to stop poisoning 3 million children [4]. [1] http://www.aopa.org/News-and-Video/All-News/2015/April/01/Bill-would-impose-escalating-tax-on-leaded-fuel http://www.aopa.org/News-and-Video/All-News/2015/April/01/Bi... [2] http://www.agairupdate.com/article_detail.php?_kp_serial=00000494 http://www.agairupdate.com/article_detail.php?_kp_serial=000... [3] http://www.flyingmag.com/blogs/flying-time/transition-unleaded-fuel http://www.flyingmag.com/blogs/flying-time/transition-unlead... [4] the link in my GP post [5] http://blog.aopa.org/vfr/?p=870 http://blog.aopa.org/vfr/?p=870
- stcredzero 11y ago
  If you could run cargo planes on beamed power, you wouldn't have to haul your power storage (fuel) to altitude. Also, given the extreme simplicity and reliability of electric motors, such an infrastructure would save huge amounts of money and also avoid externalities like atmospheric pollution. The big question, of course, is the ability to build such an infrastructure with enough reliability.
  - elektromekatron 11y ago
    Perhaps an orbiting network of solar powered satellites that can each manage large numbers of directed power beams. Though maybe that would be a non starter due to the large number of non-civilian applications.
    - stcredzero 11y ago
      Satellites? I doubt it. Too expensive. Long-duration high altitude aircraft, maybe?
- elektromekatron 11y ago
  It maybe isn't quite as bad as you think, as what really matters is the thrust for the combined weight of the engine and power source rather than just the energy density of the power source in joules per kilo. Combustion is generally pretty lousy, compared to electric, at converting joules into useful newtons.
  - masklinn 11y ago
    Combustion is about 30% efficient, electric is about 95% efficient, so for the same energy input electric gets you 3 times (and a bit) the output. Problem is, getting the same energy input via batteries weights 50~100 times as much as fuel does, and takes 15~40 times as much room. So your fuel still weighs 20~30 times as much, and takes 5~10 times as much room in your plane. And while combustion is 30% efficient part of the energy loss can be used to heat up the cabin, because at 30000~40000ft you're not exactly at sauna temperatures outside, so now you need to spend part of your electricity to heat passengers and your batteries (because most of them don't like operating at 200K)
- melling 11y ago
  How old are you? 50 years from now the world will be a lot different. It'll probably change as much as it did in the last 100, which to put into perspective: http://www.aerofiles.com/gallaudet-c2-1915.jpg http://www.aerofiles.com/gallaudet-c2-1915.jpg
  - maxerickson 11y ago
    45 years ago: http://www.museumofflight.org/747 http://www.museumofflight.org/747
    - melling 11y ago
      You probably should have gone with 46 years ago: https://upload.wikimedia.org/wikipedia/commons/1/11/Concorde_landing_Farnborough_Fitzgerald.jpg https://upload.wikimedia.org/wikipedia/commons/1/11/Concorde... What was your point? Here's a computer from 1965: http://www.columbia.edu/cu/computinghistory/a10.jpg http://www.columbia.edu/cu/computinghistory/a10.jpg Not all technology is increasing at the same rate. Adoption is another problem. Take this bullet train from 1964. Still won't find that in America. http://cdn.gaijinpot.com/wp-content/uploads/sites/4/2014/10/shinkansen-2.jpg http://cdn.gaijinpot.com/wp-content/uploads/sites/4/2014/10/...
      - maxerickson 11y ago
        Given your example, I thought you were talking about aircraft, so the diminishing returns in the recent 50 years seemed salient.
        melling 11y ago
        Nope, we were talking more about the ability to generate electricity for an electric plane, right? Battery technology, or something else that can deliver electricity. Of course, 50 years from now we'll have commercial scramjets: https://en.m.wikipedia.org/wiki/Scramjet https://en.m.wikipedia.org/wiki/Scramjet So, progress will be made on many fronts.
simonsquiff 11y ago
I read a piece by Elon Musk, who was saying that electric planes - whilst very far away - are the future of air travel. Why? Because they will allow planes to fly higher - increasing efficiency and speed. Apparently the normal 30,000 feet cruising altitude is not higher because the reduced oxygen levels at higher altitudes impact the gasoline combustion too much. Even at 30,000 feet the air is thick as soup at cruising speed, and that's why planes have not got faster for the last 50 years. Go higher, as electrics could do, and you reduce the air pressure further and could fly faster and more efficiently. Who knows when battery technology will be advanced enough, but it sounds like a goal worth shooting for (as well as the other benefits of noise reduction and environment concerns)
- masklinn 11y ago
  > I read a piece by Elon Musk, who was saying that electric planes - whilst very far away - are the future of air travel. Why? Because they will allow planes to fly higher - increasing efficiency and speed. That's a meaningless/nonsensical assertion. If we're going to ignore basically everything we can also state that nuclear is the future of air travel (and that's actually a more sensible statement, nuclear fuel has ridiculous specific energy).
  - simonsquiff 11y ago
    I'm not sure it's ignoring everything - as this article states, electric planes exist today, and are improving at a fast rate. Batteries are also improving (thanks to Musk and others), not that electric planes needs to be battery based - fuel cells could be the answer (though presumably these require oxygen so might have altitude issues). So whilst far away, it's an extrapolation from our current position. Nuclear planes don't exist today in any form, and would have major safety concerns no doubt (any accident would be pretty catastrophic)
    - masklinn 11y ago
      > I'm not sure it's ignoring everything - as this article states, electric planes exist today Prop toys exist, not "future of aviation" anything. Props being an other issue, electric planes means no turbofans. > Batteries are also improving Batteries are not improving at a rate which would increase their specific energy by 2 orders of magnitude (the difference between the specific energy of the best batteries available today and bog-standard jet fuel) in any sort of interesting timescale. And that's before considering environmental issues, most batteries don't appreciates temperatures of -20C and below. > thanks to Musk That's a joke right? Tesla's battery innovations are related to manufacturing efficiency and structural sharing. > So whilst far away, it's an extrapolation from our current position. It's not extrapolation it's daydreaming based on what is basically magical thinking. It's less of an extrapolation than dyson spheres are. > Nuclear planes don't exist today in any form Nuclear planes were demonstrably feasible (if not necessarily smart) in the 60s: https://en.wikipedia.org/wiki/Tupolev_Tu-95LAL https://en.wikipedia.org/wiki/Tupolev_Tu-95LAL
stillsut 11y ago
Electric powered flight...probably best for blimps.
amalag 11y ago
They could at least mention Hyrdogen fuel cell powered aircraft https://en.wikipedia.org/wiki/Hydrogen-powered_aircraft https://en.wikipedia.org/wiki/Hydrogen-powered_aircraft
soulsurfer 11y ago
Reminds me of a german startup that designs a vertical takeoff and landing, two seated electric plane with an interesting form factor: http://lilium-aviation.com/ http://lilium-aviation.com/ [Edit: no affiliation]
thearn4 11y ago
At NASA, we're very interested in hybrid electric propulsion. As an applied math guy, it's a very interesting and surprisingly non-trivial design problem to tackle. Even addressing the "does this really make sense?" question is tricky.
gambiting 11y ago
"In a statement, Pipistrel said Siemens prohibited the use of its motor for a flight over water." I am not sure how that could happen? Surely if they bought the engines they could have done whatever they wanted with them? Unless they were leased from Siemens or something.
- alexhawdon 11y ago
  Maybe to get permission for your flight plan when using an experimental vehicle you have to be able to show that the manufacturers of the major components have confidence it will be able to complete the proposed route safely?
  - pingec 11y ago
    Afaik both UK & French authorities gave permission for the flight to take place. It were Siemens that wanted to prevent it.
- pingec 11y ago
  Apparently Siemens loaned it to Pipistrel and suddenly wanted the motor back urgently. Additional info this thread: https://news.ycombinator.com/item?id=9850330 https://news.ycombinator.com/item?id=9850330
mathattack 11y ago
"Electric flight isn’t new—it can be traced to 1973 West Germany—but it’s not about to dominate the skies either." I think this says it all.

63 points by lelf 11y ago

I drive an electric car and fly piston airplanes. I don't see electrics replacing internal combustion in aviation in my flying lifetime. Why? Weight. The specific energy (energy per kg, edited per masklinn) of batteries sadly lags the specific energy of gasoline or kerosene, and the airplane carries that weight for the whole flight for an electric airplane. (My gas airplane gets lighter and lands as much as 1000 pounds lighter than it took off, meaning the landing gear, wing spar attachments, and brakes can all be lighter.) Many airplanes are certified for a ramp, taxi, and takeoff weight higher than their approved landing weight. Electrics will be unable to take advantage of this and must confine their takeoff weight to their landing weight. I love that such rapid progress is being made in automotive, and I'd love to see that adoption increase so we can reserve petro-based fuels for cases where their energy density provides a compelling operational benefit, such as in aviation.

fit2rule 11y ago
There is little question that carbon-based flight power is here to stay for quite some time, but that isn't really the point - which is that electric flight is nevertheless a growth industry, and there are some markets where electric flight can make a lot of sense. If all you need to do is go up and fly for 2 hours or so, then an electric plane is a viable contender for the investment - maybe we're not at the tipping point, but we are approaching it, technologically at least, a few knots at a time. It is a worthwhile goal, though. If we can somehow harness the suns' energy to get us around the world instead of using the world itself (and thus screwing it up), then we move closer to the cusp of a more viable long-term civilization. At the moment, every cheap flight to somewhere on a jet plane costs the Earth a great deal of survival potential...
nacnud 11y ago
Surely the landing gear, wing spar attachments, and brakes all have to be able to cope with an unexpected turnback and landing with most of the original weight? (not to mention heavy landings in adverse weather conditions)
- 1stop 11y ago
  I have not idea: But could this be why Planes will often dump fuel for a turn back.
- hiharryhere 11y ago
  Planes usually fly around for a bit dumping fuel if they need to turn back.
- yread 11y ago
  No see http://www.caa.co.uk/default.aspx?catid=60&pagetype=90&pageid=822 http://www.caa.co.uk/default.aspx?catid=60&pagetype=90&pagei... or http://www.boeing.com/commercial/aeromagazine/articles/qtr_3_07/article_03_1.html http://www.boeing.com/commercial/aeromagazine/articles/qtr_3... They are only certified to the maximum landing weight which typically is lower than the maximum takeoff weight. When an overweight landing (ie. the weight is higher then maximum landing weight) occurs engineers have to perform a thorough inspection of the plane structure - landing gear, spars, wings, wingbox EDIT: thanks ForHackernews
  - ForHackernews 11y ago
    > the maximum landing weight which typically is larger than the maximum takeoff weight. I assume this was a typo and you mean that the max landing weight is typically less than the max takeoff weight.
  - nacnud 11y ago
    I guess I was thinking more about smaller GA aircraft, but thanks for the detailed reply.
masklinn 11y ago
> The energy density of batteries sadly lags the energy density of gasoline or kerosene Nitpick but the energy/mass density is usually called "specific energy" to differentiate it with the more usual energy/volume "energy density". And while a battery's energy density is pretty bad, they pretty universally have a higher density than petroleum fuels and thus even worse specific energy: the best batteries have 2 orders of magnitude worse specific energy than petroleum fuels (Li-Ion or AgZn store 0.46 MJ/kg, kerosene stores 43 MJ/kg)
- sokoloff 11y ago
  Thanks for that. Yes, I was concerned with "specific energy" (energy per kg, not per m^3).
- andrewla 11y ago
  > And while a battery's energy density is pretty bad, they pretty universally have a higher density than petroleum fuels and thus even worse specific energy Is there a typo in there? Energy density (MJ/L) for batteries is lower than petroleum fuels by the same order of magnitude as the specific energy.
  - masklinn 11y ago
    While batteries have very energy density compared to petroleum fuels, on average it's much better (compared to petroleum fuels) than their specific energy. Their energy density is 15 ~ 40 times lower than petroleum fuels whereas their energy density is 50 ~ >100 times lower.
6stringmerc 11y ago
I entered the Local Motors and ARPA-E contest for the Lightweight Sedan challenge and proposed a three part method to reduce weight: Revised chassis, bio-composite materials, and a hybrid drivetrain using micro-turbines to produce electricity to power the vehicle. The contest parameters stressed that the proposal should be "research for the next 10 years." So, I cited the efficiency and extremely light-weight of micro turbines to piston engines, and postulated that increasing technology in battery / KERS systems would compliment the real-world application in time. Needless to say, I was ridiculously mad when I saw that the winning entries were 1) an aerodynamic proposal based on an exoskeleton, 2) replacing body panels with a new metallurgy compound, and some other thing that I can't recall right now. None of them really addressed the contest parameters. It basically made me swear off any more Local Motors participation. Anyway, the bright side is that I get to maintain all rights to my entry / materials, so one day, I just might have a chance to develop a concept based on these principles and show ARPA-E and Local Motors what they missed. I guess this is how Ferruccio Lamborghini must have felt at first. Sigh.
- termain 11y ago
  Exoskeleton? You mean monocoque construction (aka load bearing skin)?
  - 6stringmerc 11y ago
    No, I mean like the chassis components were on the outside of the car, like a bug. That was the crux of their entry, mollified by some talk of aerodynamic efficiency. From what I recall, the rendered images of their concept didn't even have a method of entry for the driver/passengers. No doors. It was...well, frustrating, as my tone probably conveyed. Re: Monocoque - my entry cited that format to give additional strength to the chassis/panels mating. Bio-composites are approaching the tensile strength of carbon fiber, and could potentially be much easier to mass produce and at a lower price point. I thought the implication that in 10 years, with research, such an avenue would be viable. Instead, the second place entry was some proprietary kind of new metal that could be used to replace body panels...that's it. I remember calling that entry a "body kit" because that's what it reminded me of overall.
fnordfnordfnord 11y ago
I think we might see gasoline/jet-A over electric airplanes, perhaps with or without battery storage. That would allow a few neat optimizations. You'd have more control over CG. You could have a smaller high efficiency engine that always ran at peak efficiency (or an IC engine with several modes). You could have more control over noise in urban areas. With a battery for peak/boost power, you could have a tiny engine which could supply cruise plus accessory power and use battery-backed boost for takeoff/climb. Engines that are replaceable in a few hours. All kinds of good things could happen. >Many airplanes are certified for a ramp, taxi, and takeoff weight higher than their approved landing weight. Is that common in G/A aircraft? In any case, I'd love to see a tech. revolution in GA powerplants. I've grown tired of having quaint old 1950's era tractor engines be the dominant technology.
- sokoloff 11y ago
  Once you get past about the 6200#/3000kg MGTOW mark, it's very common to permit takeoff weight to exceed landing weight. I suspect all GA turbojets and most GA turboprops are in this situation. Even the Beech Baron (a light twin) has a 100# (~16 gallons) difference in max takeoff vs max landing weight.
venomsnake 11y ago
A fuel cell that carries only hydrogen and harvests oxygen from the atmosphere ... is viable. * *the whole membrane degradation thing excluded
- trhway 11y ago
  metal-air fuel cells are in many respects even better. And with metal content around 50% they become weight comparable or better than 30% efficient ICE.
  - venomsnake 11y ago
    In that case you have lithium oxide to take care of and you have heavier plane with each second (of course most of the fuel is wasted on lifting the plane, so it may be better)
    - trhway 11y ago
      the electric planes, at least at first, isn't about just swapping ICE for electric. It is about building different planes. The current planes have evolved significantly under the limitations of ICE. The electric planes, at least initially, is about short-hoppers ("flying car" like functionality) where ICE is a no-go because of cost and noise. The electrics are well suited to build STOL and VTOL (multi-copters). With years the electrification can make its way through various hybrid schemes into much more efficient long-haulers.
coryrc 11y ago
Electric planes could stop GA poisoning everyone with lead. You could also choose a different fuel. Toy planes (general aviation) are responsible for the majority of lead pollution: www.emagazine.com/earth-talk/lead-in-aviation-fuel
- sokoloff 11y ago
  The FAA certification process is the largest limiting factor for bringing an unleaded fuel to the market. There are about 9 different formulations of unleaded fuels flying in experimental aircraft right now. I have my own "favorite", but it's unclear when, if ever, that will be available for sale to non-experimental aircraft. The magazine article you reference says that 70% of aircraft could use (a lower octane) unleaded fuel available today. That's true, but paints an incomplete picture. That's 70% by aircraft, not 70% by flight hours or fuel consumed. Cape Air and similar and other turbocharged piston aircraft are the ones that can't use the available unleaded "mogas". Those are also the aircraft that fly the most hours and thereby use the most fuel. Fixing the 172s and Cherokees doesn't move the needle much on TEL emissions. I want to get rid of the lead from my aviation fuel, both for environmental reasons and for practical reasons. (Practically, it's a pain to deal with on the supply chain side, is expensive, there's only one manufacturer of TEL worldwide, it tends to gunk and foul plugs, etc.) The FAA is the regulatory body that is presiding over this, much more than the EPA. End running the FAA to get the EPA to make another "lead is bad" proclamation won't do any good, IMO. My engines can't burn any available and certified unleaded fuel.
  - coryrc 11y ago
    AOPA lobbies to delay unleaded fuel at every opportunity [1] [2] [5]. Unleaded fuel is available now [3], but 10% of owners would have to spend some money to stop poisoning 3 million children [4]. [1] http://www.aopa.org/News-and-Video/All-News/2015/April/01/Bill-would-impose-escalating-tax-on-leaded-fuel http://www.aopa.org/News-and-Video/All-News/2015/April/01/Bi... [2] http://www.agairupdate.com/article_detail.php?_kp_serial=00000494 http://www.agairupdate.com/article_detail.php?_kp_serial=000... [3] http://www.flyingmag.com/blogs/flying-time/transition-unleaded-fuel http://www.flyingmag.com/blogs/flying-time/transition-unlead... [4] the link in my GP post [5] http://blog.aopa.org/vfr/?p=870 http://blog.aopa.org/vfr/?p=870
stcredzero 11y ago
If you could run cargo planes on beamed power, you wouldn't have to haul your power storage (fuel) to altitude. Also, given the extreme simplicity and reliability of electric motors, such an infrastructure would save huge amounts of money and also avoid externalities like atmospheric pollution. The big question, of course, is the ability to build such an infrastructure with enough reliability.
- elektromekatron 11y ago
  Perhaps an orbiting network of solar powered satellites that can each manage large numbers of directed power beams. Though maybe that would be a non starter due to the large number of non-civilian applications.
  - stcredzero 11y ago
    Satellites? I doubt it. Too expensive. Long-duration high altitude aircraft, maybe?
elektromekatron 11y ago
It maybe isn't quite as bad as you think, as what really matters is the thrust for the combined weight of the engine and power source rather than just the energy density of the power source in joules per kilo. Combustion is generally pretty lousy, compared to electric, at converting joules into useful newtons.
- masklinn 11y ago
  Combustion is about 30% efficient, electric is about 95% efficient, so for the same energy input electric gets you 3 times (and a bit) the output. Problem is, getting the same energy input via batteries weights 50~100 times as much as fuel does, and takes 15~40 times as much room. So your fuel still weighs 20~30 times as much, and takes 5~10 times as much room in your plane. And while combustion is 30% efficient part of the energy loss can be used to heat up the cabin, because at 30000~40000ft you're not exactly at sauna temperatures outside, so now you need to spend part of your electricity to heat passengers and your batteries (because most of them don't like operating at 200K)
melling 11y ago
How old are you? 50 years from now the world will be a lot different. It'll probably change as much as it did in the last 100, which to put into perspective: http://www.aerofiles.com/gallaudet-c2-1915.jpg http://www.aerofiles.com/gallaudet-c2-1915.jpg
- maxerickson 11y ago
  45 years ago: http://www.museumofflight.org/747 http://www.museumofflight.org/747
  - melling 11y ago
    You probably should have gone with 46 years ago: https://upload.wikimedia.org/wikipedia/commons/1/11/Concorde_landing_Farnborough_Fitzgerald.jpg https://upload.wikimedia.org/wikipedia/commons/1/11/Concorde... What was your point? Here's a computer from 1965: http://www.columbia.edu/cu/computinghistory/a10.jpg http://www.columbia.edu/cu/computinghistory/a10.jpg Not all technology is increasing at the same rate. Adoption is another problem. Take this bullet train from 1964. Still won't find that in America. http://cdn.gaijinpot.com/wp-content/uploads/sites/4/2014/10/shinkansen-2.jpg http://cdn.gaijinpot.com/wp-content/uploads/sites/4/2014/10/...
    - maxerickson 11y ago
      Given your example, I thought you were talking about aircraft, so the diminishing returns in the recent 50 years seemed salient.
      - melling 11y ago
        Nope, we were talking more about the ability to generate electricity for an electric plane, right? Battery technology, or something else that can deliver electricity. Of course, 50 years from now we'll have commercial scramjets: https://en.m.wikipedia.org/wiki/Scramjet https://en.m.wikipedia.org/wiki/Scramjet So, progress will be made on many fronts.

simonsquiff 11y ago

I read a piece by Elon Musk, who was saying that electric planes - whilst very far away - are the future of air travel. Why? Because they will allow planes to fly higher - increasing efficiency and speed. Apparently the normal 30,000 feet cruising altitude is not higher because the reduced oxygen levels at higher altitudes impact the gasoline combustion too much. Even at 30,000 feet the air is thick as soup at cruising speed, and that's why planes have not got faster for the last 50 years. Go higher, as electrics could do, and you reduce the air pressure further and could fly faster and more efficiently. Who knows when battery technology will be advanced enough, but it sounds like a goal worth shooting for (as well as the other benefits of noise reduction and environment concerns)

masklinn 11y ago
> I read a piece by Elon Musk, who was saying that electric planes - whilst very far away - are the future of air travel. Why? Because they will allow planes to fly higher - increasing efficiency and speed. That's a meaningless/nonsensical assertion. If we're going to ignore basically everything we can also state that nuclear is the future of air travel (and that's actually a more sensible statement, nuclear fuel has ridiculous specific energy).
- simonsquiff 11y ago
  I'm not sure it's ignoring everything - as this article states, electric planes exist today, and are improving at a fast rate. Batteries are also improving (thanks to Musk and others), not that electric planes needs to be battery based - fuel cells could be the answer (though presumably these require oxygen so might have altitude issues). So whilst far away, it's an extrapolation from our current position. Nuclear planes don't exist today in any form, and would have major safety concerns no doubt (any accident would be pretty catastrophic)
  - masklinn 11y ago
    > I'm not sure it's ignoring everything - as this article states, electric planes exist today Prop toys exist, not "future of aviation" anything. Props being an other issue, electric planes means no turbofans. > Batteries are also improving Batteries are not improving at a rate which would increase their specific energy by 2 orders of magnitude (the difference between the specific energy of the best batteries available today and bog-standard jet fuel) in any sort of interesting timescale. And that's before considering environmental issues, most batteries don't appreciates temperatures of -20C and below. > thanks to Musk That's a joke right? Tesla's battery innovations are related to manufacturing efficiency and structural sharing. > So whilst far away, it's an extrapolation from our current position. It's not extrapolation it's daydreaming based on what is basically magical thinking. It's less of an extrapolation than dyson spheres are. > Nuclear planes don't exist today in any form Nuclear planes were demonstrably feasible (if not necessarily smart) in the 60s: https://en.wikipedia.org/wiki/Tupolev_Tu-95LAL https://en.wikipedia.org/wiki/Tupolev_Tu-95LAL

stillsut 11y ago

Electric powered flight...probably best for blimps.

amalag 11y ago

They could at least mention Hyrdogen fuel cell powered aircraft https://en.wikipedia.org/wiki/Hydrogen-powered_aircraft https://en.wikipedia.org/wiki/Hydrogen-powered_aircraft

soulsurfer 11y ago

Reminds me of a german startup that designs a vertical takeoff and landing, two seated electric plane with an interesting form factor: http://lilium-aviation.com/ http://lilium-aviation.com/ [Edit: no affiliation]

thearn4 11y ago

At NASA, we're very interested in hybrid electric propulsion. As an applied math guy, it's a very interesting and surprisingly non-trivial design problem to tackle. Even addressing the "does this really make sense?" question is tricky.

gambiting 11y ago

"In a statement, Pipistrel said Siemens prohibited the use of its motor for a flight over water." I am not sure how that could happen? Surely if they bought the engines they could have done whatever they wanted with them? Unless they were leased from Siemens or something.

alexhawdon 11y ago
Maybe to get permission for your flight plan when using an experimental vehicle you have to be able to show that the manufacturers of the major components have confidence it will be able to complete the proposed route safely?
- pingec 11y ago
  Afaik both UK & French authorities gave permission for the flight to take place. It were Siemens that wanted to prevent it.
pingec 11y ago
Apparently Siemens loaned it to Pipistrel and suddenly wanted the motor back urgently. Additional info this thread: https://news.ycombinator.com/item?id=9850330 https://news.ycombinator.com/item?id=9850330

mathattack 11y ago

"Electric flight isn’t new—it can be traced to 1973 West Germany—but it’s not about to dominate the skies either." I think this says it all.