[HN Gopher] Lilium achieves first main wing transition for all-e...
___________________________________________________________________
Lilium achieves first main wing transition for all-electric
aircraft [video]
Author : tomohawk
Score : 313 points
Date : 2022-06-12 15:10 UTC (7 hours ago)
(HTM) web link (www.youtube.com)
(TXT) w3m dump (www.youtube.com)
| dwighttk wrote:
| What percentage of available battery did that 4 minute loop take?
| _Microft wrote:
| I would guess a considerable percentage because launching and
| landing takes a disproportional amount of power. Iirc their
| information correctly then launching and landing takes 10x as
| much power as level flight. That's because in these situations
| lift has to be generated by the fans instead of the wings. So
| short flights are actually disadvantageous.
| 01100011 wrote:
| Shower thought: Is anyone working on ground-assisted takeoff of
| aircraft using something like an aircraft catapult? It seems like
| it would be fairly straightforward to provide the initial
| momentum of an aircraft and save a bit of fuel & weight. Sure,
| you're not gaining _much_ just getting the aircraft up to takeoff
| speed, but it seems like an easy way to make commercial flights
| more efficient.
| carabiner wrote:
| https://www.talyn.com/
| drexlspivey wrote:
| I think I am going to stick with the commercial flights without
| the catapult if this ever happens
| blktiger wrote:
| The short answer is that catapult systems are expensive and
| require a lot of maintenance. Even many Navies don't use
| catapult assisted launches for that very reason. Additionally,
| commercial aircraft aren't designed for that kind of force
| applied to their main gear. They'd most likely have to be
| modified.
| chipsa wrote:
| Naval catapults don't apply force to the main gear either.
| Mostly is to the nose gear now, but it used to through the
| use of bridles to points on the wing (and wing spar). The
| bridles were a pain though, so they transitioned everything
| to the nose gear attachment. You can tell when a carrier
| transitioned, because they took the bridle catchers off the
| bow (the little narrow ramps at the front).
| 01100011 wrote:
| I wonder what sort of force you could generate with a series
| of electric coils in the ground? It lacks moving parts, so it
| should be low maintenance. You'd need magnets on the gear of
| the plane, offsetting the weight savings though. Yeah, you'd
| definitely need to reinforce the landing gear, but I think
| that's doable.
| pilot7378535 wrote:
| Yes, for gliders:
| https://en.wikipedia.org/wiki/Glider_(sailplane)#Launch_and_...
|
| Also related: https://en.wikipedia.org/wiki/Ground_carriage
| yosito wrote:
| Last summer, I rode in a Rubik R-26 Gobe glider, invented by
| the father of the man who invented the Rubik's cube.
| https://en.wikipedia.org/wiki/Rubik_R-26_Gobe
|
| Pretty fun experience. And if commercial airplanes ever start
| using this sort of launching technology, I imagine the
| takeoff would feel a lot smoother.
| robonerd wrote:
| This is kind of cool, but I'm skeptical that these sort of planes
| will ever be practical as much more than rich people toys. The
| power density of even speculative near-future batteries favors
| small airplanes and short flights. This doesn't really mesh into
| the existing aviation industry, so proponents of these small
| electric planes usually propose creating new markets entirely;
| e.g. _Uber for Helicopters_. But I 'm pretty skeptical that laws
| will allow regular operation of these in residential
| neighborhoods for long, if at all.
|
| Also, where is the vertical stabilizer and rudder? I assume
| they're using differential thrust in powered flight, but what if
| they lose power? Can this plane be controlled in a glide?
| rklaehn wrote:
| The energy density of gasoline does not matter at all.
| Batteries are good enough for some applications, like short
| distance flights. And the operating costs for use cases where
| batteries work _strongly_ favour batteries.
|
| Power density has not been a problem for a while. We are not
| anywhere near the theoretical limits of battery energy density.
| So as soon as there are some commercial applications for
| battery powered flight, there will be a strong economic
| incentive to get closer to the theoretical limits.
|
| Current jet engines are absolute engineering miracles that go
| very close to the physical limits to get maximum efficiency.
| But it took several decades to get there.
| whatshisface wrote:
| There is already a lot of economic incentive for lighter
| batteries.
| rklaehn wrote:
| Yes, and they are improving by a few percent every year. No
| major breakthroughs, but compounding improvements year over
| year, which do add up.
|
| Batteries have improved incredibly in my lifetime. As a kid
| I had an electric RC plane that barely made it off the
| ground. Now you can get pretty cheap aerobatic RC planes
| that easily compete with gasoline powered models.
|
| Battery powered screwdrivers used to be incredibly
| underpowered. Now I have a very decent battery powered
| rotary hammer...
|
| https://cdn.arstechnica.net/wp-
| content/uploads/2021/05/bnef_...
| robonerd wrote:
| > _The energy density of gasoline does not matter at all._
|
| Well if we're talking about commercial aviation, we're
| talking about jet fuel not gasoline. Regardless, it obviously
| matters a lot. A fully loaded 747 freighter has somewhere
| around 200 tons of jet fuel and a max payload of about 130
| tons. They already need more fuel than cargo, and that's
| _with_ the excellent energy density of jet fuel. Furthermore,
| traditional planes get lighter the longer they fly as they
| burn off their substantial fuel loads. The last 20% of the
| fuel goes a lot further than the first 20%. Batteries don 't
| get this advantage at all. (Dropping batteries from the plane
| with parachutes is a terrible idea, but I've lost count of
| the number of times I've seen it proposed..)
|
| > _We are not anywhere near the theoretical limits of battery
| energy density._
|
| This doesn't jive with what I've read. It's my understanding
| that we're already near the limits of what electrochemistry
| can give us, and future advancements are likely to come from
| improved electrode designs, with maybe 2-3x better
| performance possible if we're lucky.
| tremon wrote:
| _Dropping batteries from the plane with parachutes is a
| terrible idea, but I 've lost count of the number of times
| I've seen it proposed_
|
| Perhaps, but there is also the middle-ground solution to
| use a booster rocket assembly similar to what the space
| shuttle uses. The booster can use its own battery packs and
| if needed its own additional engines, and when the plane
| has reached cruising altitude, the booster can decouple and
| return to the airport of departure.
| rklaehn wrote:
| > Well if we're talking about commercial aviation, we're
| talking about jet fuel not gasoline. Regardless, it
| obviously matters a lot. A fully loaded 747 freighter has
| somewhere around 200 tons of jet fuel and a max payload of
| about 130 tons.
|
| You only need giant quantities of kerosene for transoceanic
| or transcontinental travel. The lilium business model
| requires a range of a few 100 km, which is possible with
| today's batteries.
|
| Very long distance air travel is impossible with today's
| commercially available batteries, but is possible with
| exotic chemistries (see below) or with hydrogen fuel cells.
|
| > This doesn't jive with what I've read. It's my
| understanding that we're already near the limits of what
| electrochemistry can give us, and future advancements are
| likely to come from improved electrode designs, with maybe
| 2-3x better performance possible if we're lucky.
|
| There are several battery chemistries such as lithium
| sulfur or lithium air that have extremely high energy
| densities. But cycle life remains very low, which makes
| them uneconomical.
|
| There has been decent progress made in improving cycle
| life, but it is still too low to be economical. There are
| military applications where a low cycle life is acceptable.
| robonerd wrote:
| > _a range of a few 100 km, which is possible with today
| 's batteries._
|
| Not with a meaningful amount of cargo it isn't; look up
| the electric planes that are actually flying today (and
| it's certainly not for want of trying, this is a very
| trendy field.) I can think of only a few niches where
| very light but expensive cargo _needs_ to go somewhere
| close-by, but faster than is possible with a truck.
| Organs for transplant, and rich people.
| FullyFunctional wrote:
| The cargo here is humans
| robonerd wrote:
| But can you carry enough of them to make the whole thing
| worth it?
| DennisP wrote:
| It used to mesh a lot better, when general aviation was much
| bigger than it is now and we had lots of tiny airports. Maybe
| we could get back to that. VTOL makes it a bit easier.
| nradov wrote:
| If you have even a tiny airport with a real runway then you
| can operate fixed-wing aircraft (possibly electric powered)
| without the extra cost and risk inherent to VTOL. Lillium and
| their competitors in the e-VTOL space are trying to create a
| new market for urban air mobility by bypassing airports and
| building new heliports, but even if they can solve the
| technical and legal challenges it's unclear if the economics
| will work.
| nradov wrote:
| Powered lift aircraft are not controllable in a glide, nor are
| they capable of autorotation like a helicopter. Any complete
| loss of power will result in an unrecoverable spin. For safety
| these aircraft rely on redundant systems, plus a parachute.
|
| Finding landing sites is going to be a major challenge even if
| they can solve the battery problems. New York City could be a
| prime market but there are only a few heliports. Politics and
| safety issues make it difficult to construct more.
| robonerd wrote:
| > _New York City could be a prime market but there are only a
| few heliports._
|
| Afaik rooftop helipads have been banned in NYC ever since an
| accident in 1977 killed five people.
| merely-unlikely wrote:
| There are three heliports on the rivers around Manhattan.
| There's plenty of space to build more but noise complaints
| prevent that from happening. Bezos wanted to build one on
| the Queens waterfront (LIC) but the city killed the idea.
| bluejekyll wrote:
| Any idea what the minimum height for the parachute to be
| effective as a life saving device?
| nradov wrote:
| Minimum effective altitude for parachutes on light aircraft
| is about 400 ft agl, but the exact number varies depending
| on the flight regime. For powered lift aircraft there is
| likely a small "dead zone" in the flight envelope: too high
| to survive a crash, too low for the parachute to be
| effective. This may or may not be acceptable depending on
| mission risk tolerance and the reliability of other
| systems.
|
| https://www.aopa.org/news-and-media/all-
| news/2018/march/flig...
| GordonS wrote:
| > too high to survive a crash, too low for the parachute
| to be effective
|
| This is probably a silly question, but couldn't the pilot
| just wait until the plane dropped below the dead zone
| before deploying the parachute?
| Andrew_nenakhov wrote:
| The lower the craft drops, the deader the zone.
| chipsa wrote:
| You're thinking about the dead zone in the wrong way:
| There's a height X where you can drop the aircraft and
| it'll absorb all the forces to have the people live.
| There's a height Y where the parachute has enough time to
| deploy and bring the aircraft to terminal velocity. If X
| is less than Y, there's a height where there's nothing to
| save you.
|
| Options to resolve this are: make X higher by making the
| structure able to absorb more energy, or make Y lower by
| having it deploy faster.
| jeffbee wrote:
| The Cirrus SR22 needs ~1000ft above ground to effectively
| deploy the airframe parachute in a spin.
| Simon_O_Rourke wrote:
| I'm guessing that if it loses power during flight then it's
| curtains for the airframe and anyone unlucky enough to be in
| it.
|
| There's lots more work to do to push it out to the mass market,
| but I could definitely see a niche for it.
| themitigating wrote:
| That's the same if a jet engine losses power
| CoastalCoder wrote:
| The movie Sully [0] opened my eyes to the amazing glide
| ratio of a commercial passenger plane like the A320. (I'm
| assuming that the movie was pretty accurate in that
| regard.)
|
| [0] https://en.wikipedia.org/wiki/Sully_(film)
| nradov wrote:
| Yes, the movie was accurate in that regard.
| t0mas88 wrote:
| Passenger jets have very good glide ratios. A 747 gliding
| with no power (all four engines somehow broken) from
| 10,000ft will get even further than a small Cessna 172
| doing the same.
|
| This is counter intuitive to even most pilots, but it's how
| efficient the wing design on a passenger jet is. Their lift
| to drag ratio is better than small planes.
| fullstackchris wrote:
| Is this achievable by the size of the craft itself? Or
| the fact that these bigger planes have 1000s of engineers
| behind them optimizing every possible factor to squeak
| out the best possible lift to drag ratio?
| p_l wrote:
| Nope.
|
| Look at the tiny wings, and at what speed it still depended
| on vertical thrust. It's going to have _horrible_ glide
| ratio, which means unpowered landings might be, well, not a
| thing, which leaves you only with emergency full-plane
| parachute as an option.
|
| Pretty much all jet engine planes can do unpowered landings
| in glide, though admittedly some have pretty high speeds
| involved - but then they operate by default only on
| airports that have facilities for such speeds.
| oliveshell wrote:
| See this famous example, where a jet airliner ran out of
| fuel in flight and glided to a successful landing:
|
| https://en.wikipedia.org/wiki/Gimli_Glider
| kayodelycaon wrote:
| Also Air Transat Flight 236.
| https://en.m.wikipedia.org/wiki/Air_Transat_Flight_236
| sokoloff wrote:
| If a [civilian] jet aircraft loses an engine, it's still a
| strong favorite to end that flight upright, intact, and on
| a runway. There are a couple dozen jet engine failures per
| year; the overwhelming majority end up in a safe
| conclusion.
|
| https://www.cbsnews.com/news/jet-engine-failures-rare-
| usuall...
| mrfusion wrote:
| Why not add a parachute? Some small planes actually build one
| in.
| merely-unlikely wrote:
| I like those a lot but they only help above some altitude
| (I think it's something like 300 or 600 ft). Ie they won't
| save you during VTOL
| codingdave wrote:
| Airplanes glide. Some better than others, but they do glide.
| hn_throwaway_99 wrote:
| That's the whole point of GP's comment. Planes glide with
| the control afforded by a rudder and a vertical stabilizer.
| Without that, it ain't pretty.
| nradov wrote:
| Powered lift aircraft are not controllable in a glide, nor
| are they capable of autorotation like a helicopter. Any
| complete loss of power will result in an unrecoverable
| spin. For safety these aircraft rely on redundant systems,
| plus a parachute.
| kayodelycaon wrote:
| I think this "plane" has a glide ratio that's only slightly
| better than a thrown rock.
| crubier wrote:
| If they aren't stupid (And I bet they aren't), they made
| several independent redundant power system. I think
| distributed power systems (i.e. lots of small engines) is
| actually on of Lilium's main strength, can be made very
| reliable.
|
| Lost 2 batteries and 7 rotors, fine, there's still 6
| batteries and 25 rotors left. Or something like that
| barnabask wrote:
| Check out their other video posted around the same time as
| this one, especially the part about changing the wheel design
| to allow for rolling landings. Seems like regulators had the
| same concern.
|
| https://youtu.be/qZ73PftBfFg
| toomuchtodo wrote:
| Enjoy the engineering achievement in the moment.
| kurthr wrote:
| A lot of the electric (mostly fuel cell) aviation startup
| industry is funded/supported by currently profitable aviation
| companies. The 1000hp motors for them are, like the airframes,
| one of the mostly off-the-shelf elements of their development.
|
| I agree that even modern batteries are pretty absurd for any
| human scale flight, though scaling laws make smaller aircraft
| more reasonable.
| amelius wrote:
| Isn't synthetic fuel much more promising?
| jeffbee wrote:
| Yeah they are, and this fact is just overlooked by people
| who aren't thinking through the implications of abundant
| renewable energy. With a surplus of renewable energy it
| makes much more sense to manufacture synthetic liquid fuels
| and burn them, than it does to power airplanes with
| batteries. The energy cycle is grossly inefficient but
| nobody is going to care because the energy inputs will be
| nearly cost-free.
| zbrozek wrote:
| CAISO hits about 100gCO2e/KWh during the day. And I run a
| solar surplus that I don't put back on the grid.
|
| I'd be really happy if there were a good way for me to
| turn excess electricity into something I could use later.
| Maybe that's hydrogen. Maybe that's capturing carbon and
| putting it into liquid fuels. Maybe that's creating
| graphite that I can use for fun personal projects.
|
| But regardless, I don't expect grid electricity prices to
| fall. Probably not in the US. Definitely not in CA.
| frosted-flakes wrote:
| I had that thought recently. Renewable energy sources
| like wind need a lot of energy storage. That is, unless
| you over-provision them so much that they can always meet
| demand even at peak times. This leaves you with over-
| production at other times, which could be used for other
| purposes that don't need to run continuously: synthetic
| jet fuel production, water desalination, etc.
|
| Basically, overprovision and then set electricity rates
| based on demand, and the renewable energy "storage
| problem" might just sort itself out. Of course, all those
| windmills and solar panels will cost an awful lot, so it
| might not be as simple as "overprovisioning".
| Sebb767 wrote:
| > That is, unless you over-provision them so much that
| they can always meet demand even at peak times.
|
| Overprovisioning solar to power the grid on ice cold,
| windless new moon night is going to be hard. Having
| somewhere to put excess energy and some overprovisioning
| is always good, but it won't solve all storage problems.
| robonerd wrote:
| From a CO2 perspective, synthetic fuels don't have an
| intrinsic advantage, unless you use biomass as your source
| of carbon. Traditionally, synthetic fuel has been made
| using coal or natural gas as the source of carbon. There is
| still some advantage to this, the nitrogen and sulfur
| content of the fuel can be dramatically reduced, which is
| great. But with regard to C02 specifically, you're
| basically burning coal. With biofuels, I think care needs
| to be taken to ensure we don't ruin the price of food for
| people by incentivizing farmers to grow fuel feedstock
| instead. Biofuels made from algae might be the best, since
| this wouldn't require the use of arable farmland.
|
| Another approach is to pull the CO2 straight out of sea
| water. Apparently the US Navy thinks this might be a viable
| approach, since their nuclear aircraft carriers have power
| to spare.
| ginko wrote:
| I believe when people say synthetic fuel they mean carbon
| neutral fuels that are made from renewable electricity.
|
| The general idea is to use electrolysis to produce
| hydrogen, then combine that with atmospheric CO2 to
| produce methanol.
|
| For instance: https://www.efuel-alliance.eu/efuels/what-
| are-efuels
| robonerd wrote:
| Atmospheric carbon capture seems like an petroleum
| industry scam to me (check the 'Members' page of that
| website.) In principle it's what plants do, but plants do
| it using scale; there's a whole bunch of them. CO2 is
| under 500ppm in our air, and air isn't particularly dense
| in the first place; the amount of air you'd need to move
| through your capture plant is immense.
|
| On the Costs & Outlook page of this site, they list their
| potential feedstocks; it's all biomass, except for the _'
| Technical Potential "Unlimited"'_ column, which mentions
| Power-to-Liquids. But how does that actually work and
| does it actually make sense?
|
| Related parody of carbon capture:
| https://www.youtube.com/watch?v=MSZgoFyuHC8
| PaulHoule wrote:
| It is possible, it's just expensive.
|
| The U.S. navy is interested in a fuel synthesizer that
| works on co2, seawater and uranium and they can pay more
| than you per gallon because you don't have to refuel an
| aircraft carrier in a war zone.
| sky-kedge0749 wrote:
| I recently commented about synthetic jet fuel in another
| thread https://news.ycombinator.com/item?id=31704829:
|
| > A problem with biofuel is scaling it up, see:
| https://ieeexplore.ieee.org/document/7498153. According
| to that article the U.S. would need to devote "an area
| bigger than Texas and California and Pennsylvania
| combined" to crops specifically for its own jet biofuel
| needs. That's just for flying, not for food or fuel for
| ground transportation or anything else.
|
| Also that article says that from 2009-2013 a $100 million
| effort was made to figure out how to get sufficient
| synthetic fuel from algae but they eventually gave up and
| went back to the drawing board.
| ncmncm wrote:
| Biofuel is an obvious dead end.
|
| The future has no place for biofuel in any substantial
| amount.
| ncmncm wrote:
| _Obviously_ in the present context "synthetic" refers to
| fuel produced using renewable energy. If you are willing
| to use petroleum, you don't need to synthesize anything
| because that is where you started, unless maybe you are
| turning NG into kerosene. But that would be a dead end
| technology, so would not return investment.
|
| Energetically, the principal synthetic fuels will be
| anhydrous ammonia and hydrogen. Capturing CO2 to make
| methane and kerosene is possible but more expensive. In
| particular, you need hydrogen as input, and must both
| capture and crack the CO2.
|
| But for some uses you still need hydrocarbons, at least
| for now. Given carbon taxes subsidizing synthetics, the
| synthetics could be competitive.
|
| In the longer term, aviation does much better with liquid
| hydrogen fuel, but it takes new airframes or, at least,
| extensive retrofits.
| systemvoltage wrote:
| Can we allow CO2 emissions if we can sequestrate it
| somewhere else? Synthetic fuels sounds like a good idea.
|
| It's capturing energy in point A and being used at point
| B. You can't just look at point B and yell "CO2
| emissions!".
| robonerd wrote:
| > _if we can sequestrate it somewhere else?_
|
| That seems to be the big _if_.
| systemvoltage wrote:
| https://en.wikipedia.org/wiki/Carbon_sequestration
| hannob wrote:
| There's been an EU funded research project that did some
| projections on the electricity needed for e-fuels. See the
| graphic on page 44: https://www.fch.europa.eu/sites/default
| /files/FCH%20Docs/202...
|
| For pure e-fuels they project 32 PWh. That is, to put it in
| perspective, more than the total world electricity
| production today. You'll want to use every technology
| available to do this in a more efficient way - batteries
| for very short ranges, hydrogen for mid ranges, e-fuels
| only for long range where nothing else works. It'll still
| be very challenging and likely the current growth
| projections of the aviation industry will be seen as
| unrealistic fantasies at some point in the future.
| lukeschlather wrote:
| > For pure e-fuels they project 32 PWh. That is, to put
| it in perspective, more than the total world electricity
| production today.
|
| Total annual electricity production is 161 PWh. THe PDF
| you linked puts it in perspective by saying that if it
| were purely powered by renewable energy it would increase
| the size of the renewable energy sector by 3 to 5 times.
| In other words this doesn't sound hard at all from an
| electricity standpoint. If electrical generation were
| half the cost it would be economical right now.
| moby_click wrote:
| From https://pubs.rsc.org/en/content/articlelanding/2020/
| se/c9se0...
|
| > We find that an electricity emissions factor of less
| than 139 g CO2e per kW h is required for this [Direct Air
| Capture system paired with Fischer-Tropsch synthesis]
| pathway to provide a climate benefit over conventional
| diesel fuel.
|
| The grid averages in most regions are higher than that. I
| don't think multiplying current renewable generation just
| for jet fuel is easy.
| bbojan wrote:
| Burning any fuel in our atmosphere produces nitrous oxides.
| Synthetic/carbon neutral fuels won't help with that.
| SoftTalker wrote:
| These can possibly be addressed by catalytic converters
| in the exhaust (not sure how feasible that is in a
| turbine engine though). In any event, it's a small
| fraction of total greenhouse emissions, dwarfed by CO2.
| Let's not let perfect be the enemy of good.
| bbojan wrote:
| Oh I wasn't concerned about their greenhouse effect
| contribution. NOx can cause asthma and bronchitis and can
| aggravate pre-existing heart conditions. They also form
| smog.
|
| Did I mention that they are bad for the ozone layer?
| kkfx wrote:
| This might give you some insights...
|
| https://www.easa.europa.eu/sites/default/files/dfu/uam-full-...
|
| ...of the idea. Witch is essentially, advertisement aside, "the
| wealthy who happen to live nearby cities, witch happen to be
| open-sky prisons^w^w factories stuffed with services to achieve
| the Chinese lockdown with workers who live in the factory, to
| work, of course ehrm, to achieve the best work life balance
| (better not say the best to who) can came and go from such erh
| smart cities in full comfort with means that made things
| closer, like if they live inside the city and goes with cars.
|
| ...In the LONG term, that means we can benefit from the economy
| of scale living "near" but far less dense than today so at that
| point in time we have finally found a way to live sufficiently
| flexible to withstand the technological, social and climate
| change still being near enough to be social and have economy of
| scale phenomenon.
|
| Or: in the short term we need a good solution for those who can
| pay, in the medium terms slaves ahem citizens have built a new
| society and new generations will finally benefit from such
| progress...
|
| In theoretical terms: maintaining roads network is expensive,
| far expensive if we also need to build new ones, like a
| potential future arctic "anthropization" due to climate change,
| so better made few railroads and waterways for heavy loads
| transports and live humans in the air, far more flexible and
| cheap. At a certain point in time if we are still alive as a
| species we will reach that point. Then the "self-sufficiency
| push" will be the key to reach that goal in an unspecified
| future.
|
| Ps if they loose power there is AFAIK only an emergency
| parachute for the entire plane. Only it demand, I suppose, a
| certain altitude to being able to be deployed...
| newaccount2021 wrote:
| ramesh31 wrote:
| >This doesn't really mesh into the existing aviation industry,
| so proponents of these small electric planes usually propose
| creating new markets entirely; e.g. Uber for Helicopters. But
| I'm pretty skeptical that laws will allow regular operation of
| these in residential neighborhoods for long, if at all.
|
| I can see it becoming more of "Greyhound for Helicopters".
| Practically every town in the US greater than a few thousand
| population has at least a local municipal airport. With
| electrification, aviation can become so cheap that all of these
| fields will just have a few commuter size electric aircraft
| that feed into to the rest of our existing airport
| infrastructure. And with the planes being so small, there's
| really no need for TSA security or anything, it becomes as
| simple as buying a ticket on your phone and hopping on the
| plane like a bus.
| repiret wrote:
| > With electrification, aviation can become so cheap...
|
| Fuel is not the dominant cost in general aviation.
| Electrification alone won't make it cheap.
| ramesh31 wrote:
| >Fuel is not the dominant cost in general aviation.
| Electrification alone won't make it cheap.
|
| It's not about fuel efficiency. In fact, any electric
| aircraft with current battery tech is always going to be
| less efficient than a jet, because jets burn oxygen from
| the air.
|
| It's about maintenance. The fixed hourly cost of aviation
| is almost entirely based on the cost of maintenance. And a
| fleet of electric aircraft will be orders of magnitude
| cheaper to maintain than turboprops and jets. That can
| unlock whole new business models of small scale commercial
| aviation that aren't possible today.
| nradov wrote:
| When you say "orders of magnitude cheaper" you can't
| possibly mean even 10x. There is more to aircraft
| maintenance than just engine repairs and overhauls.
| Electric aircraft will still require similar amounts of
| maintenance on the airframe, control surfaces, avionics,
| and interior. And some of the powered lift designs have
| literally _dozens_ of separate motors and rotors, each of
| which require periodic manual inspection.
| 908B64B197 wrote:
| > And with the planes being so small, there's really no need
| for TSA security or anything
|
| There's no need for larger planes either for zero-risk
| travelers.
| [deleted]
| akira2501 wrote:
| Granted, this is a new type of transport.. but the current
| metrics on air flight safety do not support this idea. Take
| offs and landings are the most dangerous part of flight, and
| still account for planes being more dangerous _per trip_ than
| most other modes of transport.
|
| Planning to create a plane that fills this space is planning
| to create a plane that suffers a lot of accidents for almost
| no real gain over current options.
|
| Buses are incredibly safe. If you want better busses, build
| those instead. This obsession with floating to your
| destination above the ground does not seem wise or
| worthwhile.
| ghaff wrote:
| It's trivial to create a luxury "bus" in just about any
| form factor you want to from a full-size motor coach down
| to a limo. Presumably the economics don't work in most
| cases. Of course, if you're talking small municipal
| airports in the US, the vast majority of people living
| there, especially those who can afford somewhat upscale
| transportation, probably own a car.
| SoftTalker wrote:
| Yes. Most small towns don't even have bus service to the
| nearest hub airport, because economically it doesn't
| work. And there is no arrangement of costs that will work
| out to electric aircraft being cheaper to own and operate
| than a bus.
| freemint wrote:
| In a sufficiently river/sea/ /hill/valley rich
| environment it might work if one can save on
| infrastructure cost for extra expensive roads. This is
| not most of the world though.
| nradov wrote:
| Electrification alone won't make air charters cheap. The
| aircraft themselves, pilot salaries, maintenance, and
| facilities will all still be nearly as expensive. We are
| decades away from the FAA allowing autonomous or remote
| piloted aircraft to carry paying customers in commercial
| service.
| theptip wrote:
| This was posted on HN a while ago; of course the numbers are
| aspirational but this explains their business model:
|
| https://lilium.com/newsroom-detail/why-regional-air-mobility
|
| > If we imagine for a moment that you work in an office in Palo
| Alto, you could now choose to live in Hayward (5 min flight,
| $25), downtown San Francisco (10 min flight, $50), or even San
| Rafael (15 min flight, $70).
|
| > Or maybe you want to escape to Lake Tahoe for a long weekend?
| That would be less than an hour on a Lilium Jet, at a cost of
| around $250 at launch and less in the near future. It might not
| be something you'd do every weekend, but saving you three hours
| each way might well make it worthwhile for an occasional trip.
|
| Obviously at first this will be a luxury good, but it's not
| obvious that it'll remain out of reach for the middle class.
| (Sure, it'll never be cheaper than a bus.)
|
| It's a fair question exactly how much regulatory change this
| approach requires, but my impression is that they are trying to
| operate within existing constraints (I'd appreciate any insight
| from experts in the aviation space though).
| bufferoverflow wrote:
| You would have to be making a lot of money to justify 2 such
| flights per day.
|
| 25 * 2 * 22 = $1100/mo = $13.2K / year.
| bpodgursky wrote:
| Bay bridge toll + gas + parking + amortized car ownership +
| insurance is pretty plausibly less than that already.
| Sebb767 wrote:
| You will have less mobility than with a car, though,so it
| won't replace all of it. But I agree with your main
| point, the actual premium will be much lower and probably
| worth it, considering the time saved.
| mbreese wrote:
| But if you can live in a cheaper place than Palo Alto,
| you'll make back that $15K per year in lower house
| payments. And if you only have a comfortable commute of
| 15-20 min each way as opposed to an hour (or more), your
| standard of living will be much nicer too.
| trompetenaccoun wrote:
| There's likely a reason they picked Switzerland, Munich,
| New York and California as examples ;)
|
| I'm interested in how those prices break down. Without any
| more details, it's hard to know if they're realistic at
| all.
| sydd wrote:
| The main issue is not cost, but safety and the disturbance of
| others.
|
| Safety: If you crash in a car, its very likely that you
| survive. With these a crash is very likely deadly. To reach
| safety levels like commercial airplanes costs will need to
| rise tremendously. A commercial jet needs maintenance and
| checks after each flight by trained personnel, high quality
| parts that can be tracked from the refinery,...
|
| Privacy: You dont want these flying over your house 7/24.
| They fly much lower than commercial planes, with a mediocre
| camera you could spy on anyone.
|
| Crime: What if you divert one? Will there be security
| checkpoints at the entrance?
|
| Weather: I'm no aviation expert, but these look... flimsy.
| Are they able to run on cold weather? (batteries last much
| less in cold) Are they able to run in storms? Likely not,
| even commercial planes avoid them. Then I guess they suspend
| the service during storms, since with their "local" distances
| as big as the circumference of a storm cloud?
| hef19898 wrote:
| Safety and weather are covered by certification
| requirements. Those will be somewhere between small
| aircraft and helicopters with some eVTOL specifics. If it
| gets certified those bases are covered.
|
| Privacy: Regulated airspace is your friend, plis why wait
| for one those if you can have your own drone for the price
| of one Lilium ticket.
|
| Crime: Regulations also cover airport operations, so that
| base will be covered as well.
|
| For me the question is not _if_ those aircraft are goong to
| fly (they will if it os technically possible and people
| fund development), but rather whether there is an actual
| market for those big enough to make the manufactirers and
| operators viable businesses. The last qiestion is hard
| (IMHO impossible) to answer without getting them to market
| first.
| sokoloff wrote:
| There are certification requirements for both the
| aircraft and Ops Spec approvals for Part 135 (on-demand
| charter) operations. I can see that these would be
| certified to fly (and thus eligible for Part 91 (private)
| operations) far more easily than the more stringent
| requirements for Part 135 charter operations.
|
| The FAA thinking is that you have greater understanding
| as a passenger on a Part 91 operation and are better able
| to judge the risk yourself, whereas a Part 135 (charter)
| or Part 121 (scheduled airline) operation, the public
| cannot effectively judge the safety of the operation so
| the FAA holds them to a higher standard.
|
| Single engine Part 135 is possible, but there's a large
| amount of focus on redundancy:
| https://www.aviationconsumer.com/industry-news/single-
| engine...
| sokoloff wrote:
| These seem to compete more in the helicopter realm than the
| airliner realm. That's likely to be true of the relative
| level of safety of this vs a helo vs an airliner. (I've
| sometimes quipped that helicopters are one of the primary
| predators of billionaires.)
|
| While the stated/projected costs (which I doubt will be
| achievable), these would compete very favorably against a
| helicopter on a cost basis. Without the ability to auto-
| rotate (or a functional equivalent level of safety system),
| there's no way I'm getting in one nor recommending my
| family get in one [and I'm perfectly happy flying single
| engine piston aircraft at night].
| lambda wrote:
| I work for one of these startups, Beta.
|
| We are focusing on a slightly different market than the
| other entrants; we're focusing initially on cargo rather
| than passenger transit. One initial customer is United
| Therapeutics, for transporting organ transplants and
| artificial organs to hospitals. Another is UPS, for getting
| air freight from airports to distribution centers; cutting
| out the truck trip can save a ton of time there. We are
| also making a passenger variant, but since the regulatory
| and NIMBY concerns for the passenger air taxi market
| present a lot of risk, we're not betting solely on that
| market like a lot of the other companies are.
|
| This helps with a lot of the concerns raised in this
| thread. In fact, another one that I'm not sure has been
| brought up is vertiport design and siting concerns; right
| now standards on vertiports are still a work in progress,
| and there are questions about whether it will be feasible
| to get them installed, because even with vertical takeoff
| and landing you generally need to keep approach angles of
| about 15deg clear, which means once a vertiport is
| installed you need to limit the heights of any surrounding
| buildings to keep the approach clear.
|
| To address a few of your other concerns: we're located in
| northern Vermont, we know cold weather. Actually, for our
| use case hot weather tends to be more of a concern;
| batteries and motors heat up when used, especially in the
| very high power vertical lift phase, so our limitations
| there tend to be thermal and cold air provides better
| cooling.
|
| Our charging stations also include air for cooling and
| warming the batteries; so you should be able to avoid the
| issues with batteries being cold on startup with our air
| system.
|
| All aircraft have limitations on weather that they can be
| flown in; crosswind limits for takeoff and landing, etc. As
| very lightweight aircraft, with high lift/drag, these will
| be somewhat lower than the limits for your big jumbo jets,
| but will be high enough to be useful in a lot of weather.
| All aircraft have requirements for design and testing for
| HIRF (high intensity radiated field/lightning), so these
| will all be certified to the same standard there. Aircraft
| can optionally be certified for flight into known icing
| conditions (FIKI); I believe our plan is to have the
| capability, but as an optional add on, as it requires a
| number of heating elements which add weight and complexity.
| But overall, the weather concerns shouldn't be too much
| different than for other small aircraft.
|
| As far as safety goes, that's obviously a concern in any
| aircraft. One advantage of electric aircraft is that
| electric propulsion systems are far mechanically simpler,
| with far fewer moving and wearing parts. The only real wear
| item of concern are the main bearings on the motors, and
| the landing gear. So maintenance intervals can be much
| longer than with ICE aircraft, and I expect reliability to
| be considerably higher. Additionally, electric motors can
| be much smaller and lighter, and thus can be made
| redundant. Each propeller on our aircraft will be driven by
| multiple independent motors (probably can't say the exact
| configuration at the moment), so that motor failures can be
| tolerated without catastrophic consequences.
| mike_hock wrote:
| I mean, why should regulations me more lenient on sci-fi
| chopper/plane crossovers than on regular choppers?
| dkasper wrote:
| Zero chance of helicopters in cities after 9/11. You can't fly
| helicopters over SF or Manhattan anymore except for medical
| purposes.
| mlyle wrote:
| Helicopters aren't banned over Manhattan, etc, despite
| repeated efforts to do so.
|
| In the late 1970's, all the building-top helipads stopped
| operation after repeated accidents.
|
| Still, there's the helipads along the river and a VFR
| corridor in and out of Manhattan. In 2009, the altitude rules
| for the corridor got a lot stricter because of repeated fatal
| accidents.
| merely-unlikely wrote:
| I was under the impression you can only fly over the
| rivers. Is that not true?
| mlyle wrote:
| There's a VFR corridor over the rivers where you don't
| have to talk to air traffic control. Otherwise, you're
| going to need to talk to LaGuardia.
|
| If you're a tour operator and want to use a city
| heliport, you need to sign a very restrictive agreement
| about operations, too-- which allows only limited
| overland stuff (e.g. flying over Yankee's Stadium/the
| Bronx). Mostly because people were sick of tourist
| helicopters constantly hovering over Central Park.
|
| https://cityroom.blogs.nytimes.com/2010/04/30/rules-
| tightene...
|
| None of this has anything directly to do with 9/11.
| Crashes of tourist helicopters and noise concerns has
| caused the city to clamp down on use of helipads. Crashes
| of air taxi operations in the 1970s caused the removal of
| the vast majority of helipads.
| rklaehn wrote:
| There are also big cities outside America. Plenty of
| helicopters in Sao Paulo...
|
| https://www.youtube.com/watch?v=uiybWbyfQIY
| lastofthemojito wrote:
| How is Blade flying people between Manhattan and the
| Hamptons?
|
| https://www.blade.com
| merely-unlikely wrote:
| The helipads are all on the rivers not inside Manhattan
| ur-whale wrote:
| Zero chance _in the US_ which - increasingly - is not the
| center of the world.
| JumpCrisscross wrote:
| > _can't fly helicopters over SF or Manhattan_
|
| Both cities have plenty of potential even with overland
| banned. New York has a thriving helicopter business between
| boroughs, up and down both sides of Long Island and to and
| from the airports. The Bay Area isn't similarly knitted
| together, but there is no good argument for not having an
| electric hop from _e.g._ Mountain View to SFO.
| woodruffw wrote:
| Worth noting that the "thriving" helicopter business is
| uniformly disliked by residents, due to noise pollution[1].
|
| [1]: https://www.nydailynews.com/news/politics/new-york-
| elections...
| CoastalCoder wrote:
| Can someone comment on why the parent would be (as of this
| writing) downvoted?
|
| I'm wondering if there's some context I'm missing.
| hef19898 wrote:
| Best guess? Because the helicopter restrictions have
| nothing to do with 9/11.
| marcosdumay wrote:
| The low energy density of batteries favors _large_ planes and
| short distances.
|
| The only reason you are seeing them in small planes is that
| electric propulsion makes VTOL viable, and VTOL favors small
| planes. There is just this niche in aviation that can't be
| filled at all by fossil fuel engines, so it's the first to
| adopt electric ones.
|
| And yes, regulations will be the most important factor for
| those. I imagine it all depends on how silent those planes can
| be. But I doubt safety will be the limiting factor.
| Deritio wrote:
| Whenever I hear air taxi, I think about water bottles and
| airport security.
|
| I don't want some rich dude flying over my house just because
| he/she can afford to take a airtaxi from the airport to city
| center while everyone else uses car or train.
|
| For other use cases they can do what they want. Australian
| outback perhaps.
|
| But airspace pollution and a potential small airplane
| crashing down in a city? No way.
| inglor_cz wrote:
| Air taxis are really useful in places divided by natural
| obstacles.
|
| Hop over a fjord, hop over a mountain range. Much cheaper
| and eco-friendly than building bridges and tunnels
| everywhere, especially if the population density isn't
| high.
| idlehand wrote:
| These kinds of places are also generally suitable for
| hydropower and geothermal energy which gives considerable
| amounts of cheap electricity.
| [deleted]
| p1mrx wrote:
| > a potential small airplane crashing down in a city? No
| way.
|
| Drones ought to have megaphones that scream DRONE CRASH
| IMMINENT before impact.
| jstummbillig wrote:
| > No way.
|
| Wait until you see the motor carriages they claim are going
| to replace horses one day.
| tpxl wrote:
| When a motor carriage loses power, it stops. When a
| helicopter loses power, it kills people.
| underdeserver wrote:
| When a helicopter loses power it glides, safely, to the
| ground - assuming it's being flown by a qualified pilot.
|
| https://en.m.wikipedia.org/wiki/Autorotation
| kevin_thibedeau wrote:
| That is a fantasy that almost never works out in real
| life. Autorotation is only feasible with enough forward
| air speed and control authority. Most helicopter crashes
| happen outside that narrow zone of survivability. Even if
| an autorotation is semi-pulled off it's likely to be a
| hard landing that causes significant injuries.
| sokoloff wrote:
| Autorotations are regularly trained (and often taken all
| the way to touchdown during training). The checkride for
| private and commercial rotorcraft has a power failure at
| hover taken all the way to touchdown as part of the
| standard.
|
| Autorotations are by no means a "gimme", but if every
| autorotation "likely" caused significant injuries, there
| wouldn't be enough helicopters or pilots to go around (no
| pun intended).
| robonerd wrote:
| > _That is a fantasy that almost never works out in real
| life._
|
| Can you quantify this?
|
| > _Most helicopter crashes happen outside that narrow
| zone of survivability._
|
| AFAIK the majority of helicopter crashes are not caused
| by a loss of engine power, but autorotation is relevant
| specifically in that context. It's not relevant to
| helicopters crashing into hills during storms, or hitting
| wires with the rotor, or anything like that. We're
| discussing what happens if the engine stops, not all
| accident scenarios.
|
| > _Even if an autorotation is semi-pulled off it 's
| likely to be a hard landing that causes significant
| injuries._
|
| Yes, but it's better than being dead.
| jackpeterfletch wrote:
| I guess the question is - can we maintain the standard
| that is 'qualified pilot' as it is today while making it
| accessible enough for this to scale.
|
| Learning to drive and learning to fly isn't the same bar
| today.
|
| And if Lilium think Palo Alto to San Francisco could be
| $50, they're gonna need _alot_ of flights to balance
| their costs.
| jstummbillig wrote:
| I think it's safe to assume this class of vehicles (and
| likely any new class of vehicles from here on out) is not
| designed to be piloted by a human past its prototype
| stage.
| gnulinux wrote:
| You can recognize that cars are going nowhere and it's
| best if we embrace this fact in our own ways (either by
| being a car owner, or working around car-designed cities
| the way we prefer), but still note that our cities could
| have been designed better from scratch that doesn't favor
| cars. Similarly, avoiding the same mistake now for
| helicopters wouldn't be inconsistent with living with
| cars.
| jstummbillig wrote:
| That seems reasonable, but what is missing (at least in
| this branch of the debate) is data and counter arguments
| that will not clearly peter out while the technology
| matures, if they are even trying to be factual to begin
| with.
|
| As an example, just on the topic of safety: Why would we
| assume these machines are relatively dangerous once they
| reach production? Just because they fly? I know of at
| least one category of vehicles where on that basis our
| intuition fails us to this day.
|
| And what happens when they do fail? They are not going to
| explode randomly or purposefully target the closest
| building. So what are the chances of all fail-safes
| failing, and catastrophic outcomes occurring?
|
| Why would we assume whatever this technology eventually
| enables will be operated by human pilots? I for one would
| be fairly surprised if that was to happen at any
| noteworthy scale. Clearly, the interesting part about
| this prototype is electric flight, not its HID, agreed?
|
| So let's build cool things (electric flight is
| potentially a cool thing) and then gather actual data
| about other things it brings (some maybe not so cool),
| before we "no way" it without any facts on the basis of
| weak conjecture and personal feelings.
| trompetenaccoun wrote:
| The difference is we don't live in the sky. As long as
| there isn't noise pollution (and electric planes are
| supposedly a lot quieter), you have to try really hard to
| create and issue here. Aviation is getting ever more
| automated and safer.
| thescriptkiddie wrote:
| The motor carriage and its consequences have been a
| disaster for the human race.
| nostromo wrote:
| They do this already. They're called helicopters.
| staunch wrote:
| > _They do this already. They 're called helicopters._
|
| This is dangerously close to the infamous HN Dropbox
| critique[1] :-D
|
| And it's likely wrong in the same way.
|
| 1. https://news.ycombinator.com/item?id=9224
| [deleted]
| SideburnsOfDoom wrote:
| Well, _electric_ helicopters or electric helicopter-
| equivalent-vehicles would be a step forwards, correct?
| ben_w wrote:
| On the one hand, yes.
|
| On the other hand, making it cheap enough that mono-
| millionaires can do it regularly is going to make a big
| difference compared to the status quo.
| wildmanx wrote:
| > mono-millionaires
|
| Ah right, moving it from 0.1%-ers to 1%-ers is really
| going to make a big difference.
| jxf wrote:
| Roughly 10% of Americans are millionaires, for reference
| (though I doubt all of that is liquid).
| edg-l wrote:
| this comment reminded me of this
| http://www.temporarilyembarrassedmillionaires.org/
| woodruffw wrote:
| Sources online show that about 8% of Americans are
| millionaires, with a significant bump during COVID
| (probably because of the stock market.) About 10% of
| households are.
|
| It's hard to find precise qualifications for how they
| determine that, though. The households figure doesn't
| include primary residence value (why?), and the
| individual statistics don't mention liquidity. I suspect
| that only a small percent of that 8% actually has $1+
| million liquid.
| idlehand wrote:
| Definitely not liquid cash, but assuming that a not
| insignificant portion of those people are retirees or
| planning to retire soonish (which is when net worth
| peaks), I wouldn't be surprised if the percentage of
| decently liquid assets like stocks and bonds are higher
| than you might think.
| brrrrrm wrote:
| About 10x, right?
| woodruffw wrote:
| I don't know. The idea that a bunch of people with a
| couple of millions of dollars in wealth can now zip
| around above my house (and further alienate themselves
| from civic reality, even more so than cars do) seems like
| a pretty bad outcome.
| ghastmaster wrote:
| That is essentially how progress begins in every
| industry. Wealthy people pay for new tech with their vast
| fortunes, and many times, their lives. Once they work out
| the kinks and economies of scale take over, the less
| wealthy to enjoy the same tech at higher levels of safety
| and lower prices.
| vidarh wrote:
| Helicopters are expensive to rent. If Lilium achieves
| even 10x the cost they've suggested they can reach in the
| past, they'll be attractive to a customer base who'd
| never be able to afford regular helicopter rides.
| prvit wrote:
| > airspace pollution
|
| Bit of a fake concern, no?
|
| >potential small airplane crashing down in a city
|
| Is that really much worse than a SUV driving into a
| building?
| SideburnsOfDoom wrote:
| > Is that really much worse than a SUV driving into a
| building?
|
| Yes
| SapporoChris wrote:
| Think of it this way. If an SUV drives into your building
| you can sue and make some money. But if some really rich
| person crashes their flying gizmo into your building you
| can sue and make a lot of money!
| SideburnsOfDoom wrote:
| So, are you saying that you think that the worst that
| happens in car crashes is "someone could sue"?
|
| please don't waste our time.
| woodruffw wrote:
| I can't sue if I've been incinerated by an uncontrolled
| lithium battery fire.
| voldacar wrote:
| Neither could you sue if you had been struck and killed
| by an SUV. The end state of your reasoning is that nobody
| can ever do anything that involves risk because someone
| might die and be unable to sue. Sounds like an awful
| world
| woodruffw wrote:
| Emphasis on "killed." I don't want to be struck by an
| SUV, but one hitting my apartment at ordinary NYC
| residential street speeds (at least, pre-COVID) is less
| likely to kill me than a plane crash.
|
| Risk is a community exercise. You don't (or rather,
| shouldn't) get to externalize _disproportionate_ risks
| upon the commons because it makes your life easier.
|
| (An example of such a consideration: what happens when
| the fire department shows up? They know how to deal with
| a car accident; are they going to have the presence of
| mind not to douse a vehicle that looks like a normal
| personal aircraft in water?)
| [deleted]
| hef19898 wrote:
| With more and more SUVs and truck beimg EVs that doesn't
| change much. Well, eVTOLs will burn longer, not that it
| matters because a large SUV will burn long enough to not
| matter to _you_.
|
| And I'd bet a lot more on the crash safety of aerospace
| cerrified batteries than those of the automotive sector.
| closedloop129 wrote:
| In that niche, why are batteries needed? Couldn't those
| planes be constructed with gas turbines that generate the
| necessary electricity?
| t0mas88 wrote:
| VTOL works fine with turbines, nearly all large helicopters
| use turbine engines. They don't use the turbines as
| generators but instead connect both engines to the rotor
| via a gearbox.
| marcosdumay wrote:
| It's a matter of the weight/power relation. While batteries
| suck on weight/energy, their weight/power is great.
|
| The lower that relation, the smaller you can make your VTOL
| vehicles, and the smaller the vehicles, the cheapest and
| more economical they are on total.
| dr_dshiv wrote:
| > I imagine it all depends on how silent those planes can be.
|
| I agree. I'd say, though, not just how silent, but how
| pleasant sounding. Aesthetics of sound could make or break
| this industry.
| inb4_cancelled wrote:
| You either get a chop-chop-chop, or a bzzzt, both
| incredibly loud. It's not the engine that makes the noise,
| it's mostly the propeller/rotor. The only advantage of
| electric VTOLs is easier manufacturing and better control.
| detritus wrote:
| Props need feathers.
| dr_dshiv wrote:
| > You either get a chop-chop-chop, or a bzzzt
|
| Well, for instance, if they could line up the harmonics
| to create a missing fundamental (eg with the addition of
| external sounds), they could make propellers present an
| artificially lower pitch.
| Judgmentality wrote:
| Your solution to them being too loud and annoying is to
| make them louder and hopefully less annoying?
| dr_dshiv wrote:
| Yes. It's possible that louder but less annoying is more
| viable, wouldn't you say?
| vkou wrote:
| I would say the most viable solution is to not subject
| hundreds of thousands of people to an incredible amount
| of noise pollution, so that a couple of playboys get to
| skip a taxi ride to the airport.
|
| Private-transport helicopters or equivalents have no
| place in cities. The gain is in no way worth the cost.
| marcosdumay wrote:
| There is plenty of space to change the number of
| propellers, total area, and rotational velocity and
| change the sound profile of the plane.
|
| There is also a lot of space on how you maneuver it on
| the landing and take-out, so you make less sound when it
| matters the most.
|
| There is the entire thing about minimizing weight too,
| that also reduces sound, but it's also not clear how much
| can be done.
|
| Overall, it's not clear at all how much noise the eVTOL
| planes will make.
| aliswe wrote:
| do you have any references to back these statements up? I am
| not an expert but I did read in a hacker News comment that
| the energy density of gasoline is about 14 (reading that
| article, its 50) times higher than a "normal" battery.
|
| if that is true (I do not think that he left references
| either) then I would think that your statements seem less
| plausible.
|
| a replier who later deleted their comment left a reference
| saying the energy density is 50 to 1, comparing lithium-ion
| battery to diesel:
| https://www.batterypowertips.com/comparing-ev-battery-and-
| fu...
| [deleted]
| kevin_thibedeau wrote:
| Combustion aircraft also benefit from the weight reduction
| as fuel is consumed.
| swarnie wrote:
| Did the Harrier just get skipped by the rest of the world?
|
| fossil fuel VTOL was cracked in the late 60s.
| alluro2 wrote:
| When talking about practical small plane with relatively
| acceptable noise levels and fuel efficiency, I don't think
| Harrier counts as it "being cracked". 125dB at 100 feet
| from the plane, very limited time it can spend on vertical
| takeoff while loaded, limited situations
| (fuel/weight/thrust ratio) in which it can hover at
| all...If it was cracked, the newer iteration of the "same
| thing" - F-35B - wouldn't be so complex and take so many
| billions to develop...
| nradov wrote:
| And the Harrier only barely worked at all. For most
| operational missions, they couldn't really make true
| vertical take-offs and landings. Instead they usually had
| to make short ground rolls to get some lift from the
| wings, or have a carrier ship sail into the wind. And the
| mishap rate was appalling.
| andrepd wrote:
| https://www.youtube.com/watch?v=aH4b3sAs-l8
| cesarb wrote:
| > The power density of even speculative near-future batteries
| favors small airplanes and short flights. This doesn't really
| mesh into the existing aviation industry,
|
| How short are these short flights? The hugely popular Ponte
| Aerea (https://en.wikipedia.org/wiki/Ponte_A%C3%A9rea) has a
| flight duration of one hour.
| robonerd wrote:
| That flight is about 230 miles (365 km) as the crow flies,
| and they're doing it with 737s that seat 100+ each and fly
| dozens of these flights a day.
|
| Compare that to this battery plane that can fly 200 miles:
| https://cleantechnica.com/2020/01/29/rolls-royce-claims-
| its-...
|
| These aren't in the same ballpark; they aren't even playing
| the same game. If you want something to replace that plane
| route, I suggest buying a lot of buses.
| scythe wrote:
| >[The electric airplane] doesn't really mesh into the existing
| aviation industry
|
| The reason small electric planes haven't taken off [1] is that
| they simply haven't proven their cost advantage. About one-
| sixth of the cost of a flight is fuel, which can be difficult
| to tax because of jurisdiction shopping. A third is labor,
| including taking care of the plane. Seven percent goes to
| building the plane. From:
|
| https://www.travelandleisure.com/airlines-airports/airfare-d...
|
| Optimistically, electric planes could be cheaper to fuel, build
| _and_ maintain. That 's enough to upset an entrenched industry.
| But it's not clear how it should be organized, and the
| infrastructure mostly doesn't exist. Plus, the scale you expect
| to operate at depends on battery technology, which has been a
| little up in the air [2], and you don't want to design your
| operations around 1000-mile ranges if it's going to be 2000 in
| ten years.
|
| 1: Sorry.
|
| 2: Sorry. But see:
| https://www.nature.com/articles/s42004-022-00626-2
| ur-whale wrote:
| There's other aspect than the pure economic aspect:
|
| Noise
|
| VTOL
|
| When both are combined, this makes Urban flight closer to
| feasable.
| dzhiurgis wrote:
| Dropbox vs rsync moment right here
| bozhark wrote:
| Air taxi is their market
| momenti wrote:
| Lilium's plane has 30 engines, multiple independent battery
| packs, and electric motors are way more reliable than jet
| engines (due to being so much simpler). A Lilium plane may have
| a 1000x higher chance of a crash in case of full engine
| failure, but perhaps that can be compensated for by 1000x times
| simpler/redundant propulsion technology. This seems to be very
| hard to assess in theory, so we probably just have to wait and
| see how it performs in practice.
| vidarh wrote:
| At some point at least their design also included a whole
| plane parachute. I don't know if that's still the case.
| SoftTalker wrote:
| 30 engines = 30x the chance that at least one will fail.
| Maybe one is tolerable. How many can it lose and still fly?
| leoedin wrote:
| That's all very well, as long as there's no common modes of
| failure. Redundancy can be a means to achieve reliability,
| but not always. Imagine the cause of failure is a bug which
| kicks in at a specific time of day, or an integer overflow
| which happens after a certain amount of uptime, or all the
| motor drivers are susceptible to a specific RF frequency. It
| doesn't matter how many motors you have if they're all
| susceptible to the same failure mode.
| mbreese wrote:
| _> integer overflow which happens after a certain amount of
| uptime_
|
| It's not just electric powered planes that have to worry
| about such things... this was an issue for the Boeing 777
| Dreamliner too. If it was powered on for longer than 248
| days, it could lose all electrical power due to an overflow
| in the generator.
|
| https://www.engadget.com/2015-05-01-boeing-787-dreamliner-
| so...
|
| I'm not saying it isn't a concern, but rather it is a
| concern for all planes (and vehicles for that matter). Many
| commercial passenger planes are now fly by wire. If you
| lose electrical power, you'll also lose control. So, while
| we're talking about purely electric planes, the problems
| are universal.
| hef19898 wrote:
| That's what certification is there for, isn't it?
| ben_w wrote:
| I can't possibly comment on any specific design, but what I'd
| _like_ is something that can replace road ambulances.
|
| This is partly because I live right next to a busy crossroads
| and often get multiple _simultaneous_ sirens; but I do also
| wonder how faster they can arrive by going as the crow flies
| rather than following street layouts, and how much they have to
| slow down both for traffic and for blind corners.
| dzhiurgis wrote:
| I keep thinking remotely controlled cargo operations,
| especially around bad terrain and difficult water features.
| Great for proving design and catching bugs for initial years.
| jlmorton wrote:
| This is one of the primary reasons I've bought into the eVTOL
| revolution. I'm also skeptical about these filling city
| skies, due to safety, noise pollution, etc. But the market
| for emergency and special purpose vehicles alone is enormous.
|
| The US market size for existing _air_ ambulances is itself
| $4.5 billion dollars annually. The market size for standard
| ambulances is nearly 10x that.
|
| When you expand this to the rest of the world, you can easily
| see a 100+ billion market for these sorts of vehicles,
| whether in ambulance services, firefighting, agricultural, or
| any number of other activities.
|
| It's still possible we develop near-to-city eVTOL airport
| systems for short distance travel. But even absent that, I
| still think there's a big market opportunity.
| SoftTalker wrote:
| For critical patients helicopters are already used. For
| patients who need to get to a hospital but are short-term in
| stable condition, is the extra expense of an air ambulance
| justified, in a health care system that is already
| unaffordable?
| clouddrover wrote:
| > _The power density of even speculative near-future batteries
| favors small airplanes and short flights._
|
| Use a hydrogen fuel cell instead:
|
| https://www.bbc.com/future/article/20210401-the-worlds-first...
|
| https://www.aircargoweek.com/zeroavia-and-monte-strike-deal-...
|
| https://www.flyingmag.com/joby-secretly-bought-a-hydrogen-el...
|
| https://interestingengineering.com/german-firm-record-altitu...
| mLuby wrote:
| I love that tell-tales are still part of vessels thousands of
| years later.
| [deleted]
| rklaehn wrote:
| This is a major milestone for them. Very nice to see the
| indicators suddenly transitioning to laminar flow.
|
| It is a shame that they only stayed in this flight regime for a
| few seconds, but they will now gradually expand the envelope.
|
| Here is a good article explaining the tradeoffs they make vs.
| more traditional VTOL craft with larger propellers:
| https://ir.lilium.com/news-releases/news-release-details/tec... .
| TLDR: they accept more inefficient performance during hover
| because they won't stay in this flight regime for long.
| beefman wrote:
| Transportation economics are dominated by the passengers per
| pilot ratio. Small vehicles aren't economic unless they are
| piloted by a passenger or an AI.
|
| AI piloting should be easier with aircraft than cars.
| drexlspivey wrote:
| Fuel costs are in the order of hundreds of thousands of dollars
| per flight. Surely that's much more expensive than the pilot
| costs?
| redleader55 wrote:
| According to [1] fuel costs are in the tens of thousands for
| intercontinental flights. Pilot training is around 200k USD
| [2] and thousands of hours to be accepted to fly reputable
| companies' planes. I wouldn't call pilot costs negligible.
|
| [1] -
| https://www.google.com/amp/s/simpleflying.com/commercial-
| air...
|
| [2] - https://fly-ga.co.uk/how-much-cost-become-pilot-learn-
| fly/
| hef19898 wrote:
| We are living in a world were co-pilots sometimes pay to be
| allow?d to fly in order to get flight hours in towards type
| ratings and promotions. Initial pilot trainig through
| airlines, and paid by those with almost guaranteed
| employment afterwards, is a thing of the past. Most pilots
| pay for their own training now. Ehich leaves salaries,
| which are indeed negligable.
|
| Even if you accoubt for training costs, those are
| negiligable whem compared to fuel, maintenance,...
| beefman wrote:
| For commercial jetliners? Yes, but they have a very high
| passenger:pilot ratio already.
|
| Also, the order is tens of thousands (for a typical
| transatlantic flight).
|
| Across transportation modalities, fuel costs are usually a
| minor contributor to total cost. For a commercial airline
| flight, about 10% of ticket price.
|
| See also, this comment of mine on a recent story about the
| Joby eVTOL: https://news.ycombinator.com/item?id=29705650
| a-dub wrote:
| i don't know what the proper term is, so i'm just going to make
| bjork happy and call them aerodynamic scientifical tassles.
|
| are they just recorded visually by a camera and then inspected
| manually for a test flight or are they part of some kind of
| active sensor system.
|
| cool stuff.
| carabiner wrote:
| Tufts and they are recorded on video.
| [deleted]
| cousin_it wrote:
| I think the ideal personal aircraft would work like a quadcopter
| during takeoff and landing, but unfold wings for cruising flight
| with much better efficiency. It seems there's already such a
| drone called Transwing, I hope they make a personal aircraft like
| that.
| cvccvroomvroom wrote:
| Not really a plane so much as a expense, semi-hovering, large
| drone, inefficient consumer of electricity.
|
| An efficient vehicle would have significant aerodynamic
| properties like a glider. Instead, it's mostly pushing itself up
| rather than using an airfoil.
|
| Also, in terms of climate change, widespread use of anything
| similar would be devastating for the environment as it's an
| inherently extremely uneconomical mode of transportation.
|
| If we wanted better transportation for less energy, it look like
| a train.
| staunch wrote:
| Pretty exciting. I consider this a real proof of concept for
| shuttlepods AKA flying cars. I'm sure there's a lot of work left
| to do this shows how much is already possible with _relatively_
| little effort by a _relatively_ small company.
|
| Seems like there's a few advances that should enable it to
| finally happen:
|
| Automated: so there's no pilot to make mistakes and drive up
| costs. Automated flying is easier than navigating streets, so
| this is probably already doable at scale even though self-driving
| cars are taking longer than hoped.
|
| Electric: so the at-scale/long-term cost per flight can be nearly
| zero. Seems possible something like this could be manufactured
| for $100k at scale and fly (with maintenance) for multiple years.
|
| Multi-rotor w/efficient DC motors, multi-battery pack w/advanced
| batteries, and multi-computer w/advanced processors: so there's
| no single point of failure and lots of opportunity to recover
| from failure, and to enable easy VTOL without runways.
|
| The Wright brothers would love it. Their initial vision was to
| not need specially built runways or airports. It turns out that
| was "too early" of an idea to be practical but we're getting
| close.
|
| An "infinite highway of the air" (Wilbur Wright) is an exciting
| goal.
| amelius wrote:
| Why does this look like it's entirely CGI?
| AustinDev wrote:
| Resolution and framerate. What were you watching the video in?
| Zak wrote:
| I am (perhaps unreasonably) annoyed by the mixed units. The
| narrator and captions are using knots for speed, which is
| standard for aviation in most of the world. The on-screen display
| is using km/h, which is standard for everything else in most of
| the world.
| 369548684892826 wrote:
| And ft/s for vertical speed. Really got a bit of everything
| going on there!
| aero-glide2 wrote:
| That is standard for vertical speed everywhere
| bernulli wrote:
| That's funny for someone with aero-glide2 as user name. I'm
| used to metric variometers in gliders.
| chipsa wrote:
| And yet, excepting two countries (IIRC), altitude is
| normally in feet for ATC. Which means instruments are in
| feet.
| throwaway019254 wrote:
| It has vertical take off? It must burn so much electricity for
| that?
|
| Wouldn't be classic horizontal take off more efficient?
| mrfusion wrote:
| I was actually just thinking that VTOL aircraft could solve the
| housing crisis considering we're using 1000s of acres of prime
| real estate in every city for airports. Anyone want to flesh out
| that idea and write it up?
|
| (I'd be curious if anyone could correct my thinking instead of
| downvoting)
| TulliusCicero wrote:
| There's no way airports use enough land to be able to 'solve
| the housing crisis' by using it for housing.
|
| The housing crisis is an entirely self-created problem by the
| societies it exists in, and it has little to do with amount of
| land. For example, Japan and South Korea have relative little
| land -- and in the case of Japan, very little non-mountainous
| land -- relative to their population, and yet rent prices there
| are quite affordable, even in the megacities of Tokyo and
| Seoul.
|
| Western cities tend to have some combination of greater
| restrictions on density/housing forms, and harder/more
| ambiguous red tape to develop new buildings. Relaxing these
| regulations would at least alleviate, it not outright solve the
| crisis, but people just don't wanna do that. It's not a
| technical issue, it's just that the political will isn't there.
|
| As an example of ambiguous red tape, take the ubiquitous
| "community meetings" that are common in US cities any time
| there's a major new development. It's common for neighbors to
| raise random objections that may or may not relate to any
| building codes or zoning regulations, and then a planning board
| to force the developer to adapt to those objections, or just
| block the project outright.
|
| What this means, is that there's really two sets of laws: one
| on the books, that was developed through normal democratic
| processes like city council members voting on them, or local
| initiatives passing, and then the second set is whatever the
| local residents feel like accepting in their heads.
|
| We would never accept this for other laws, the idea of, "well
| sure you didn't break any laws on paper, but local residents
| don't like what you did and a few raised a stink about it at a
| community meeting, so you're going to jail anyway." But that's
| how building permitting actually works. You can't just follow
| actual laws, you have to make the subset of people who show up
| to community meetings all happy.
| hrgiger wrote:
| I didnt downvote, I think those VTOLs also at the end gonna
| land somewhere, its reminds me this pic [1].
|
| https://www.google.com/search?q=1+bus+vs+related+cars&newwin...
| jillesvangurp wrote:
| They can land on roofs, in parks, any open area large enough
| basically.
|
| That kind of is the whole point being able to land anywhere.
| Short term, anything that already accommodates helicopters
| would be good enough. The problem with those is mainly that
| helicopters are very noisy so people don't like to have
| helipads everywhere.
|
| But considering, these VTOL planes tend to be a lot less
| noisy, having them land in more places might end up being
| less controversial.
|
| Either way, it would be a perfectly valid way to commute
| 50-80 miles in ten minutes or so and skip the 2 hour car
| ride. I could see that become a popular thing. Initially
| probably quite expensive but the pitch for these devices
| seems to be that they could be mass produced cheaply.
| hrgiger wrote:
| Yes my answer was for the airport, I definitely would like
| to see them around and try it!
| jltsiren wrote:
| Any powered aircraft large enough to carry a person is
| inherently noisy and dangerous. All serious vertiport
| proposals I have seen for quiet electric aircraft assume a
| dedicated facility at least as large as a city block. And
| even those are only feasible if there is no significant
| NIMBYism in the area.
|
| Rooftop landing pads could work, at least in principle.
| They are however risky enough that Western cities often
| outright ban them in urban areas or limit their use to
| emergency situations.
| mrfusion wrote:
| That's true but runways are quite long and we need several of
| them at least.
|
| And we wouldn't need the same level of centralization for
| small landing pads.
| ncmncm wrote:
| No city will be scrapping its runways. Period. So if you
| add VTOL pads that takes more of high value real estate.
| andbberger wrote:
| the hover power density is insane, 2500W/kg
| ur-whale wrote:
| Oh, wow, that is intense indeed. Where did you get these
| numbers? Was it in the vid?
| m00dy wrote:
| and again, we see an amazing german engineering.
| [deleted]
| carabiner wrote:
| Making a comment to represent all aerospace professionals getting
| major gell-man amnesia vibes from this thread.
| xeromal wrote:
| Is hydrogen gas dense enough to power an aircraft? I don't think
| battery technology will be dense enough to power aircraft in our
| lifetimes, but I feel like hydrogen could play a part
| NegativeLatency wrote:
| https://en.wikipedia.org/wiki/Lockheed_CL-400_Suntan
| jillesvangurp wrote:
| There are a few flying prototypes of various sizes, so clearly
| there's a big flaw in your argument.
|
| In principle you can burn hydrogen in a jet or even in an
| internal combustion engine. Both have already been shown to
| work. Fuel cells are another possibility of course. As far as I
| understand it, most plane manufacturers are already designing
| planes with hyrdogen as a power source. Particularly for big
| Jets, the consensus seems to be that that is happening.
|
| The main challenge in the market is similar with what we've
| seen with existing car manufacturers. Changing technology
| disrupts them and threatens their profitability. So, you see
| companies that are talking the talk but not really committing
| to much beyond that. E.g. Airbus and Boeing have lots of fancy
| concept planes but not much in the line of actual planes being
| designed and marketed yet.
|
| As for battery, there are several battery powered planes flying
| and certified (or in the process of being certified). Most of
| the companies behind those are following up with longer range
| versions that they've already announced.
|
| Maybe aviation fuel goes a bit further but it is very
| expensive. Especially for general aviation, the value
| proposition might look pretty good a few years down the line
| with better ranges and charging speeds and lower cost. That
| does not even require that much in terms of breakthroughs in
| energy density either. Anything certified today is using
| battery tech that is several years old and was probably picked
| conservatively to speed up the process. That's just the nature
| of the certification process. What's flying legally today was
| the state of the art about half a decade ago in terms of
| batteries. Probably not that impressive compared to the latest
| electrical cars.
| ggreer wrote:
| Hydrogen looks good on paper but has a lot of practical issues.
|
| - Currently, the most economically efficient method to obtain
| hydrogen is by methane steam reforming. This releases a lot of
| CO2.
|
| - If you want to get hydrogen without making CO2, you'll need
| to use electricity to split water. That's around 60-70%
| efficient. If you used the same electricity to charge a
| battery, it would be over 90% efficient.
|
| - Hydrogen embrittlement is a problem for tanks and pipes. This
| means you can't easily repurpose natural gas infrastructure.
|
| - Hydrogen has no odor, and adding an odorant can foul fuel
| cells. The most effective solution is to add hydrogen sensors
| everywhere, increasing costs.
|
| - Hydrogen burns with an invisible flame. It's also much more
| easily ignited than gasoline and will burn in a wider range of
| concentrations. (Though unlike gasoline, it won't pool up.)
|
| - Hydrogen is a small enough molecule that it will slowly
| permeate through a sealed tank. Newer tanks have coatings that
| reduce this, but research is ongoing.
|
| - Remember the ideal gas law? The pressure change involved in
| refilling a hydrogen tank causes the nozzle to get very cold.
| Even in southern California this can freeze the nozzle to the
| tank, limiting refill speeds.
|
| - Hydrogen is light, but tanks are heavy. The Toyota Mirai's
| tanks weigh 87.5kg but can only store 5kg of hydrogen.
|
| Considering all of these disadvantages, I don't think hydrogen
| aircraft are going to happen.
| p_l wrote:
| Hydrogen has been tested, including in Soviet Union which
| considered it the future fuel for airliners, tested on Tu-154M
| modified for cryogenic hydrogen fuel.
| panick21_ wrote:
| Lithium Battery are already enough to power some airplanes.
| Airplanes now in development using current battery tech are
| already targeting many niches.
|
| They will not fly across oceans for a while but a lot of
| aviation is limited to one continent.
|
| And beyond that, the cheaper operational cost, can change how
| flights routes significantly and even open more markets.
|
| The problem with airplanes is partly that it takes a very long
| time to design a new one and the cost are significant. To
| create a longer range electric plane, you need to really start
| from the ground up, and rethink the airplane. Even with cars
| this took 10-15 years. For planes it will be even more
| difficult.
| stareatgoats wrote:
| Agree: https://newatlas.com/aircraft/hypoint-gtl-lightweight-
| liquid...
| skykooler wrote:
| Hydrogen has an excellent energy-to-weight ratio, but in terms
| of energy-to-volume it's even worse than lithium-ion batteries
| as a gas. This is why proposals for hydrogen airliners usually
| need a complicated cryogenic setup to store it as liquid
| hydrogen instead.
| ncmncm wrote:
| You don't need a "complicated" cryogenic setup. You just need
| insulated tankage. But it won't fit in the wings, so you need
| new airframes or fuel nacelles.
|
| We have a very great deal of experience with fuel nacelles
| already, because that is what a "drop tank" looks like; you
| just omit the "drop" complication. The advantages over
| inboard tankage are safety, possible retrofitting of existing
| fleets, and short plumbing runs.
|
| Once LH2 aircraft are used on any route, kerosene craft will
| be wholly unable to compete, even without carbon taxes.
| Carbon taxes could be spent on accelerating the transition.
| hgomersall wrote:
| Or a radically different airframe design. One that perhaps
| is much bigger and flies slower but is very low weight (by
| virtue of being mostly full of hydrogen).
| ncmncm wrote:
| A different airframe design would take a long time to
| field, and with inboard tankage arguably less safe.
| Kerrick wrote:
| There is already a type-certified electric aircraft.
| https://www.pipistrel-aircraft.com/aircraft/electric-flight/...
| marcosdumay wrote:
| Hydrogen looks like the perfect storage medium for aviation,
| except that every way people created to store it is either very
| dangerous or reduces its energy density enough that it becomes
| similar to batteries.
| runlevel1 wrote:
| Having motors along the whole trailing edge of the wing surely
| kills the glide ratio of this, right?
|
| Losing power on one side seems like an even more frightening
| prospect. Even if the motors were somehow allowed to freely
| windmill, that's a lot of surface area for drag.
|
| At the very least, it must have some unusual aerodynamic
| properties.
| melony wrote:
| Why is the airflow so turbulent over the trailing edge? Is it
| even considered a full transition?
| rklaehn wrote:
| > Having motors along the whole trailing edge of the wing
| surely kills the glide ratio of this, right?
|
| The motors are running at reduced thrust and changed geometry
| during all parts of the flight.
|
| Regarding power loss: Last time I read about it in more detail,
| the impellers were organised in groups of 3, and you could lose
| one such module anywhere on the plane, even on the front
| canards, without issues. On the wings you could probably lose
| several.
|
| If you lose all electricity everywhere that would be a bad day,
| but the same is true for a modern airliner with fly by wire
| controls.
| nradov wrote:
| Modern airliners are equipped with ram air turbines to
| provide electrical power for critical systems even if they
| lose all engines and the APU.
| fmakunbound wrote:
| Recently read unleaded aviation fuel seems to be an
| insurmountable problem for the FAA. Will it be that hard with
| electric aircraft or is it further along?
| p_l wrote:
| Completely unrelated.
|
| The issue with unleaded fuel is that the goal is to make it a
| drop-in replacement on all engines that currently use
| AVGAS100LL, which is the only remaining leaded fuel in large
| use (a lot of small planes can actually fly on unleaded
| aviation fuels and there are some available, it's just 100LL is
| "default" fuel when thinking of piston engines). So they have
| to certify that if you swap the fuel, preferably without any
| modifications, then it's safe to fly.
|
| Battery powered aircraft go through normal certification
| process for a new design.
| akrymski wrote:
| 1. We already have VTOLs - helicopters. How do the economics of
| this compares to helicopters?
|
| 2. Surely hydrogen is a better fuel source for VTOL?
| sigmoid10 wrote:
| 1. Helicopters are technically VTOL, but what you'd really want
| is something that can transition between vertical takeoff and
| horizontal flight using conventional wings, which is much more
| efficient and stable when travelling from A to B.
|
| 2. VTOL requires engines which provide very high thrust and
| very short response time during vertical ascent. This is
| incredibly hard to do using combustion engines - which includes
| hydrogen - but trivial using electric engines, which is why
| every cheap drone can easily fly using only vertically mounted
| propellers.
| robonerd wrote:
| > _VTOL requires engines which provide very high thrust and
| very short response time during vertical ascent_
|
| Not necessarily. That's how you do it with electric
| multirotors, because it's simple and electric motors are good
| at it. With turbine powered VTOLs, the rotor blades are
| actuated to change their angle of attack, and consequently
| how much lift they're producing, using swashplates and cyclic
| controls. That's what traditional helicopters do, and what
| tiltrotors like the V-22 do too.
|
| Incidentally I think tiltrotors are what you're describing as
| the VTOL ideal; they take off like helicopters then
| transition into horizontal flight using conventional (albeit
| stubby) wings. They're not exactly a runaway success and have
| had a rocky history, but they do work.
| reacharavindh wrote:
| This has been one of my "shower thoughts"..
|
| If jet fuel is very efficient and dense for the more demanding
| take off and low altitude legs of the flight, we aren't there
| concepts that do a hybrid of jet fuel and electric powered
| flights that use the electric propellers only where they are
| efficient, leaving the existing system for the more challenging
| tasks like take off?
| ramesh31 wrote:
| Same problem as all hybrid power systems; weight and
| complexity. You can't get away with generalist designs in an
| aircraft the way you can with a land or water vehicle. Carrying
| around the weight and drag penalties of an unused engine would
| more than detract from any efficiency gain with an electric
| auxiliary.
| Ekaros wrote:
| Also unlike with sea where efficiency gains from hybrids out
| gain the mass and volume losses, same doesn't apply to air.
|
| Also, some of the engine types like turboprops are pretty
| good already. And hybrid systems likely won't make gains and
| probably even lose quite a bit.
| krallja wrote:
| Then you have two different energy storage areas plus two
| different drive trains, and the associated weight gain that
| implies. Hybrid road vehicles make it work because they have
| the weight supported by the ground, plus the additional benefit
| of regenerative braking, which evens out energy usage in stop-
| and-go and hilly travel. Planes don't work at all in either
| scenario.
| cjbprime wrote:
| There are some electric gliders which at least use the same
| intuition -- you need a ride for takeoff, but then there's an
| electric sustaining motor for once you're in the air (and don't
| have lift).
| rwmj wrote:
| Or can you have a 100' long cable to directly power the lift
| off and first hundred feet of the flight? (For a conventional
| runway takeoff, some kind of powered tracks.)
| amluto wrote:
| Aircraft carriers effectively have powered tracks. As I
| understand it, this is currently quite dangerous and
| expensive.
| akira2501 wrote:
| Because we use the engines to generate hydraulic power and
| electric power, and on larger planes it drives the air
| conditioning. The engines do a lot more than just provide
| thrust.
| p_l wrote:
| In addition to other comments here about increased weight and
| complexity...
|
| There's an area where it makes sense, and it's being trialed in
| few places. Namely electric propulsion for taxiing.
|
| You see, Taxiing on jet engines is very, very, very inefficient
| - you stay pretty much in worst fuel economy all the time to
| the point that taxiing burns more fuel than few hundred
| kilometers of cruise on the heaviest airliners. In fact
| optimizing taxiing is important enough that landings are
| calculated to ensure you have shorter distance and can reuse
| kinetic energy from landing, and depending on plane it might be
| norm to shut off all engines except one during taxi.
|
| So there's experimentation with either adding electric
| drivetrain to main gear or having remote-controlled pulling car
| or quick-detachable (and also remote controlled) drive blocks
| that could attach to main gear. This way the plane would only
| start the engines just before going onto its designated runway.
| dwighttk wrote:
| I am not an expert
|
| This doesn't seem to make any sense to me. If taxiing is so
| inefficient, why not use the pushback carts to push/pull the
| planes into position?
|
| I've been to many more airports that make the plane taxi for
| quite a distance, like 20 minutes (not just sitting and
| waiting, but moving) to get to the gate than ones that
| "ensure you have shorter distance and can reuse kinetic
| energy from landing"
| p_l wrote:
| That's essentially what the prototype projects are doing,
| except optimized for taxiing vs. "just" pushback or
| maintenance moves - normal pushback truck is not exactly
| prepared to handle high traffic taxiing, partially due to
| how communication between aircraft and pushback is handled.
|
| So those projects investigate a solution that is optimized
| for the whole taxi trip at full traffic at the airport,
| including electric solutions to avoid currently heavy
| diesel pushback trucks.
| SV_BubbleTime wrote:
| This all just furthers my idea that if I'm ever a time
| traveler, I'll try and convince the past to make airplanes
| that all have aircraft carrier sling shot systems... for fun.
| stavros wrote:
| Taxiing is the process of getting the plane to the
| slingshot.
| simonsarris wrote:
| Yeah, you'd need to convince the past that "tugboats but
| for aircraft" is a good thing to standardize.
| baybal2 wrote:
| Lilium is a shady company
|
| First, it's people without even most basic aeronautic backround
| designing an aircraft.
|
| Second, the number of flaws with their scheme being pointed by
| experts is so huge they cannot possibly get certified without
| throwing out everything, and redesigning completely from scratch.
|
| Third, they finally hired somebody with the background, but so
| far nobody seen any change from "submarine ramen startup," to a
| serious company happening. Unlike with SpaceX, where Elon
| promptly yielded to professional engineers shutting down his
| fantasies like an SSTO design, 3D printing the whole rocket, or
| developing an ion engine to replace chemical one for last stages.
|
| Fourth, they lash out on all criticism with "you have no vision,"
| it's "aircraft 2.0," and similar dismissal.
|
| Fifth, they courted investors with physically unachievable
| performance figures.
|
| To me it's very clear, the company is heading the way of "HTML
| supercomputer"
|
| P.S. Speak of the devil, it's already starting:
| https://www.bloomberg.com/press-releases/2022-06-02/lilium-i...
| heisenbit wrote:
| They have 600 people, onboarding a veteran Airbus exec as CEO
| and are located in the south of Germany which is the center of
| the German aircraft and high tech manufacturing industry. On
| the surface they pass my smell test.
|
| From their website: > As Co-founder and VP Product, Patrick
| leads the global digital and physical product strategy owning
| the technical operation readiness of the aircraft and its
| mobility service . He holds a PhD in Aerospace Engineering from
| the Technical University of Munich.
|
| Claiming they have no clue seems to be without facts.
| bouchard wrote:
| Their website isn't exactly up to date.
|
| Dr. Patrick Nathen who published Lilium's white paper
| detailing their aircraft architecture has left his VP role
| and is now an engineer within their flight mechanics team
| [0].
|
| [0] https://www.linkedin.com/posts/dr-patrick-
| nathen-1a0840b3_en...
| baybal2 wrote:
| snek_case wrote:
| I'm also highly skeptical. I've heard from someone in the
| industry that their original demos were intentionally
| misleading. They had images of the Lilium aircraft taking off
| and flying for a bit, but what they didn't tell you was that
| the thing that was flying was essentially a large foam model
| that probably weighed 1/10th of what the real thing would. I
| don't know if that's the case anymore, but I wouldn't
| personally invest my own money in them though. Joby seems like
| they have a much more promising electric aircraft.
|
| I don't have a position in either company nor in any electric
| aircraft stocks.
| hrgiger wrote:
| That law firm looks like quite active on stock market [1].
| There are like hundreds of them I saw on the news.
|
| [1]
| https://www.globenewswire.com/en/search/organization/Portnoy...
| panick21_ wrote:
| > Unlike with SpaceX, where Elon promptly yielded to
| professional engineers shutting down his fantasies like an SSTO
| design, 3D printing the whole rocket, or developing an ion
| engine to replace chemical one for last stages.
|
| What's the source for that?
___________________________________________________________________
(page generated 2022-06-12 23:00 UTC)