All-electric Cessna Grand Caravan makes maiden flight | Hacker News Reader

All-electric Cessna Grand Caravan makes maiden flight

flightglobal.com

311 pointslxm255 comments

Fantastic Skydiving vehicle.. If you can get 9 people (+ gear) 12'000ft on a 30 minutes flight, then you can glide all the way down for the next load. at $6 worth of fuel it would be a game changer.

Wondering if they could do regenerative braking with the props on the way down.

In theory yes. In practice the amount of regained energy would probably be negligible and not worth the loss of positive flight control it would entail.

Seriously, $6 for 30 min at ~100mph is pretty amazing. There are lots of cars that are less fuel efficient.

How much would that cost with conventional fuel?

A lot. Perhaps 75 gallons/hr. Jet fuel is currently a about $1/gallon.

Even a much smaller plane like a 172 can easily burn $50/hr just in fuel. Much lower flow rate, but it’s leaded a gas at about $4.50/gal

Way more than that these days. There’s only one supplier of 100LL, and even they don’t want to be in the business anymore.

Its not just the fuel cost, maintenance of electric motors is substantially cheaper. Plus, there's no need to transport and store specialty Avgas.

The article isn't totally clear on this point, but I wonder if the $6 included the costs for taxiing and taking off, or just the 30 minutes in the air?

You’d have to swap batteries to keep the flight cadence i think.

From the article:

“In airline service, operators would need to recharge the batteries between flights, with charging times correlating closely to flight times, says Ganzarski. That means the batteries would need about 30-40min of charging following a 30min flight. The weight of the batteries makes swapping spent cells for fresh cells unfeasible between flights, he says.”

Yeah i wasnt very clear. Drop zones keep those planes moving all day long. It could be done but the substantially increased amount of time spent ’refueling’ means you’d either need more planes or just accept fewer customers.

What I suspect would kill this for sky diving is recharge time. Even if fuel expenses go to zero, it's not going to be viable if it has to recharge for several hours after every hop.

What makes you think it's 7 hours? Any off the shelf EV can charge to 80% in under an hour. Some can do it in under 30 minutes.

Did you read the article? It states 30-40 min recharging after a 30 min flight.

Which means you now need two airplanes to do what one did previously.

Realistically a skydiving flight would be more, as your climbing at full power much more than a short hop commuter flight normally would.

Battery swaps. In the air is next. Especially for city surveillance drones....

For surveillance drones it's going to be wireless power. Either microwave or laser.

Or solar, if the threat profile is low.

Could even combo the two approachs...have a large high altitude solar "mothership", that beams directed power at the drones.

PV is good enough for drones if wing area is large, the aerodynamics are super-efficient, and it's daytime.

Or 5G ;)

A lot of the expenses in flying arise out of regulatory requirements. Want to carry passengers? Pilot needs a license that take several hundred hours minimum to obtain. Want to use a part in an airplane? Getting it through the FAA certificating process will inflate its cost by several multiples. Want to operate an aircraft? You need to get it inspected every $fixnum number of hours of operation by a mechanic who in turn has to do everything the 'certified' way and is himself certified by the FAA.

It's these costs, not fuel costs, that account for a big percentage of the cost of flying. There's no meaningful way to reduce the cost of flying without reducing them. Perhaps electrics will incur much lower costs in maintenance, reducing costs somehow.

Well, don't discount fuel.

I had the oppurtunity to spend an hour in a T-6 trainer a number of years ago. This was the primary trainer used by Air Force in WW2. Big radial engine. At full throttle (which we were mostly at, as we were doing acrobatics), that eats through fuel at about 40 gallons/hr. That's $200/hr just in gas, for a plane that carriers 2 people and isn't really all that powerful.

Fuel typically accounts for 20-30% of airline operating expenses. For 2019, it accounted for 23.7% [1].

1: https://www.iata.org/contentassets/ebdba50e57194019930d72722...

Gas is a huge deal in large passenger planes where instead of miles per gallon, they actually measure efficiency in gallons per mile.

The 747 for example eats about 1 gallon per second (~3600 gallons per hour) according to this source: https://science.howstuffworks.com/transport/flight/modern/qu...

We measure fuel efficiency for cars in "liters per 10 km" in my country.

This is absolutely true, hence why the Cessna is so cheap to operate. Once the engine and power system are certified everything else is good to go.

The tax free/subsidized fuel era is likely to end fairly soon (unless we're going to fail badly at climate change mitigation measures).

Amazing that the only thing you hear is the wind rustling by.

Silent planes would be welcomed by many people living in densely populated cities with high air traffic.

They're almost giving away apartments near Pearson Airport in Toronto, for example.

The price per square foot in that area is ~10x lower than the rest of the city and for good reason. (You are constantly bombarded by the sound of jet engines passing by).

Props still make significant noise, especially at takeoff RPM.

A friend of mine owned a house under the approach path to a medium-volume reliever airport (KBED). All of the piston airplanes that flew overhead were perfectly pleasant (at least to me), but the jets were notably more annoying.

Carrying more power/noise, more speed, and more disturbance to stay flying while dirtied up, the difference was night and day. I suspect the PT-6 powered C208 would already fall on the “not so annoying” side of that spectrum (closer to the piston props than the turbojets’ noise profile), so changing fuel might not provide that much relief to those who bought houses near airports.

I have a theory that we'll be able to reduce the RPM and increase the torque of these engines, versus conventional gas turbines and piston engines, thereby reducing the tip speed of the blades

Maybe. The PT6A already has a gearbox, so the engineers are presumably able to choose a reduction ratio and prop RPM quite independently of the gas and power generator rotational speeds. (There are still torque limits in the gearbox output, though it seems the same constraints would face an electric motor.)

In most planes, pilots are already able to chose their propeller RPM somewhat independently of torque by varying the pitch of the propeller. However, pilots typically optimize for rate of climb and not noise in order to get out of the low altitude / low airspeed danger zone as quickly as possible.

Yes. What GP is talking about though is changing the range of speeds available for pilot selection by changing the prop length, airfoil, maybe number of blades, and other design parameters. IOW, the design elements, not so much the operational element. Similar to how the C421 cruises at 1800-1900 prop RPM to give a(n eerily) quieter cabin.

"i.e." is functionally the same as your use of "IOW"; IMHO, FWIW.

https://dictionary.cambridge.org/dictionary/english/ie

IOW made me think "I often wonder", but it didn't fit so I had to look it up: "in other words". I think i.e. is cuter.

/digression/nit-pick

Welcome digression/nit-pick/valued feedback.

Thanks!

eh, as torque and prop size goes up... tip speed also goes up.

Or you can add more blades. Of course, you eventually hit a limit no matter what.

Considering the rate at which the general aviation fleet turns over (~none in ~forever), and that the typical Cessna is flying around with a World War 2 engine or its closely related descendant, I predict that it will be roughly infinity years before people who live at the ends of airports stop cursing the noises.

Of course, if they just outlaw 100LL avgas and pass some noise regulations the problem will solve itself.

I was never clear on why leaded avgas wasn't banned long ago. I know I've run across information on the internet about aircraft engines that can run on unleaded.

You can read these other replies, but the shorter explanation is that the AOPA is in all relevant respects the NRA but with aircraft instead of guns, and the owners have achieved cold-dead-hands status with their obsolete planes.

Not accurate. The AOPA typically takes positions that protect public safety, such as opposing Trump’s attempted giveaway of our ATC to the airlines.

However, the GA industry should be condemned for its failure to face the writing on the wall about leaded gas, which has been obvious since the ‘70s. On the other hand: Until recently, stifling certification requirements made it nearly impossible for these low-volume manufacturers to innovate.

Nobody wants leaded gas.

The other sham being perpetrated is advertising some plane engines as running on “automotive” gas. This is BS, because that means only PURE gasoline, not gasohol. I challenge you to find a gas station selling 100% gasoline. I haven’t seen that in decades. So the touted “mogas” is nearly as much of a niche fuel as 100LL.

https://www.pure-gas.org

They're working on it. Can't ban it since many airplanes still require it.

I’m not entirely sure I buy this argument. Ban it effective on a fixed date in a few years and introduce a favorable regulatory regime to help with replacements. If some planes won’t be able to fly, so be it.

Alternatively, introduce a Pigouvian tax: charge an obscene and increasing amount to burn leaded fuel.

This is kind of like the regulations that permit grossly polluting old collectible cars to operate. Sure, they have history, but that’s not a sufficient excuse to allow them to operate unmodified near other people.

Most piston engine aircraft in the country require, by regulation, 100LL. Oil companies and the FAA have been working for years to develop a replacement and came very close a couple years ago, but since the FAA strongly favors safety and reliability over almost any other consideration it takes a very long time to collect enough data to have confidence a potential replacement is truly equivalent. We have ~80 years of safety data for 100LL.

Generally speaking, airports are reluctant to spend money on a second set of tanks, pumps, etc. required during a transition period; though some have - particularly in the midwest where there are a lot of less regulated homebuilt aircraft that can burn alternative fuels.

A lot of pilots would love to burn something else. 100LL is relatively nasty and builds up in engines, shortening their life. It's even actively discouraged to burn 100LL in some more modern small aircraft engines like the Rotax 912 and pilots like myself who run that engine look for non-leaded fuel whenever practical because it's healthier for the engine. But well maintained aircraft last just about forever and the legacy fleet is absolutely enormous.

"...it takes a very long time to collect enough data to have confidence a potential replacement is truly equivalent. We have ~80 years of safety data for 100LL"

It sounds odd to put it this way, because leaded gasoline started being phased out over 40 years ago. In an alternate universe, we would now have 40 years of safety data for unleaded and for leaded.

> we would now have 40 years of safety data for unleaded and for leaded.

When lead was banned in auto gas, it was replaced by MTBE, which itself was banned in most states by 2007. The alternative to MTBE is Ethanol, which is currently used in auto gas. But Ethanol is incompatible with aircraft because it is corrosive to aluminum (and tends to cause more serious vapor-lock problems in fuel lines).

In other words, there's no widely-used blend of fuel that could even potentially have 40 years of safety data. Pilots are already used to paying a lot for fuel (more than auto gas), so there's money at stake if someone can come up with an unleaded alternative. It's just that someone has to invent that safe alternative first.

On top of that, fuel is a particularly sensitive issue to the FAA because fuel and engine malfunctions are currently the 3rd and 4th leading causes of aircraft accidents (and this is after the FAA has spent decades on safety programs to reduce fuel-related accidents).

I was generally aware of MTBE, but I didn't know it was universal since the 70s nor necessary for all grades of fuel. What about iso-octane?

Also, I happen to have a car from the 80s and in looking for information about the consequences of using fuel with ethanol, some say it can be a problem while other people say at that point in time it was designed to handle it. So I'm not clear on what diversity there was in the types of fuel available over time.

> nor necessary for all grades of fuel.

That's moving the goalposts.

Piston airplane engines typically (but not universally) have high compression ratios, so they require fuel with a high octane rating. In fact, the only avgas that contains lead today is 100LL (100 octane, low lead).

If you want to have a discussion about lead in avgas, you're having a discussion specifically about 100 octane fuel.

> What about iso-octane?

Definitionally, 100 octane fuel has anti-knock properties similar to 100% iso-octane. You may be able to make an approximately-100% iso-octane blend for lab tests, but it's not really possible to manufacture it in commercial quantities.

Keep in mind, "premium" auto gas is usually less than 93 octane, and even that has ethanol.

But Ethanol is incompatible with aircraft because it is corrosive to aluminum (and tends to cause more serious vapor-lock problems in fuel lines).

Incidentally, this is also an issue with small engines in things like garden equipment --- the ethanol tends to degrade plastics over time too.

The problem is there hasn't been a suitable 100-octane unleaded replacement until very recently (see: G100UL or UL102), and lower octane fuels cause detonation. Last I checked, how well the replacements perform is still an open question.

Everyone in aviation wants to get off 100LL fuel, we're just waiting for the FAA to certify one of the replacements as safe.

We have safety data for leaded fuel .. that says it's a neurotoxin.

We also know that 100LL is shelf-stable for years and is compatible and safe (from the perspective of those riding in the plane) to use with just about every piston aircraft engine in existence. We don't yet have enough data to know if that's the case for the potential replacements. Automotive gasoline is too low-octane and not stable enough to be used most aircraft, which for some aircraft results in engine failure in flight. There are ongoing efforts to develop an alternative aviation fuel blend, but as I mentioned previously - this takes time.

A couple years ago we got close to having an approved alternative - Swift Fuel's UL94. However as an example for why this is hard: one of the objections to that fuel was that it didn't weigh the same as 100LL, meaning its use would alter weight and balance designs of the aircraft that use it. For most airplanes that's not a big deal, for some it is.

We have 80 years of aircraft flying around designed more or less around the characteristics of one specific fuel blend and most of those aircraft have decades of life left in them. We all want to get off 100LL, but we also don't want aircraft falling out of the sky as a result.

Of course

But in aviation you're not only worried about the knowns, but also the unknowns. Example: JAL 123, BA 38, TWA 800 and other cases where you believed things to be safe but in reality they were a ticking time bomb and/or would trigger in very weird conditions.

I’m an owner and pilot of one of the previously mentioned planes that run on leaded fuel. The current issue with your plan is that for a vast chunk of the GA fleet there is no certified alternative to leaded fuel. Some planes have supplemental type certificates (STC) available that allow them to burn unleaded fuel, but many do not (such as my Grumman Tiger). It’s not just the engine, it’s the fuel system in the plane that must be certified- this is not just a paperwork drill, there have been failed certification attempts because the fuel system couldn’t deliver enough fuel pressure at certain temperatures.

The FAA is required to evaluate the impact of new regulations on the existing fleet. A change that would eliminate or place a prohibitively high tax on leaded fuel would likely be shown to eliminate half of the GA fleet. This will not be approved until the impact can be reduced. Developing and certifying new engines and fuel system components for all the different aircraft type certificates is totally infeasible; a new fuel substitute is pretty much the only option.

The FAA has made huge regulation changes before but there has always been an alternative. The recent ADS-B mandate requires about $5k of new equipment before a plane is allowed to fly where Mode C transponders were previously sufficient. This is/was expensive for many private pilots, but was deemed to be acceptable for the safety benefits gained. Some owners have chosen not to add the ADS-B equipment and haven’t been allowed to fly in some parts of the country, but they can still fly most places. A fuel regulation that grounds half the fleet with no alternative regardless of the price is a completely other level of impact.

The FAA and most pilots want an alternative to leaded fuel (at least for the assumed cost savings if not for the environment). Energy companies are working on unleaded substitutes but current options still require an STC to burn. You probably won’t see leaded fuel going away until there is a universally approved replacement that can just take the place of 100LL at every airport in the country. Edit: or barring a complete drop-in replacement, at least an option that can be shown to work in existing engines and fuel systems without requiring major R&D.

It doesn't seem like you're addressing the pollution/health effects to the population caused by burning leaded gas and the relative harm of that versus the benefit of keeping the existing fleet flying. Is that because the pollution is so small or that the pollution just is not relevant in your opinion?

For the vast majority of the population, the number of cars passing by their house each day will be many times the number of planes burning leaded fuel flying overhead.

The vast majority of the population will never fly in a leaded gas powered plane, so I'd think the harm is much more than the gain. Said in another way, it probably wouldn't take much convincing to get a proposition passed to ban leaded gas for aviation.

There's a number of essential services that rely on small aircraft, even if you're not personally flying on them as a passenger.

Lab specimens, search and rescue, law enforcement, aerial photography for the "satellite" maps on your phone, power line surveying, transportation to remote parts of the country. Not to mention training for both future airline and military pilots.

Just because they're not economical for passenger service, doesn't mean they don't have an important role.

And again, I don't think you'll find many people in aviation who wouldn't like to move away from leaded gasoline. They're just waiting for the FAA to certify a replacement.

On the other hand, the amount of leaded fuel burned is tiny compared to automotive fuel. Roughly 0.1% of all fuel sold in the United States.

Yes it's bad. Yes we need to get away from it. Yes it's being worked on and will happen eventually. Also please at least recognize that it's a hard problem.

https://www.flyingmag.com/when-will-we-see-unleaded-av-gas/

Is high-octane unleaded or jet fuel the more likely replacement? (It might be called "jet fuel," but it's similar to diesel.)

High-octane unleaded. There's a couple options that are being tested right now.

Is the slow turnover because you don't have the same fatigue because the cabin isn't pressurized, older Cessnas are already decent, airframes haven't gotten that much better, and it's pretty easy to add modern Garmin avionics to an old plane?

The typical non-electric Cessna Grand Caravan doesn't use avgas (they have turboprop engines), so outlawing leaded wouldn't ground them.

Those people can curse all they want, but the airports predate their homeownership.

As much of a dick move as it is, it's not uncommon for homeowners to band together and work through local government to take down sources of noise that long predate them. When the source is a small airport or a local racetrack they often win.

The date the airport was built is nor always important. People in my area are upset because FAA nextgen approaches always fly precisely over the same guy's house every time, where they used to be a bit more scattered. Now the Oakland airport was built in 1927 and most of these houses date from the 1940s, but air travel has increased a lot on the intervening decades.

You should not be able to hear a small plane at idle on landing approach, and VFR final approaches are not charted (can substantially vary in ground track.)

So talk to a local FBO owner and work out an alternate landing for that "same guy's house."

Source: commercially-rated airplane pilot.

The angry neighbor club isn't upset about GA on approach, they're mad because the new WNDSR TWO arrival into OAK flies a tight corridor right along the ridgeline where people live in the Oakland hills. Here's the flight that most recently flew it: https://flightaware.com/live/flight/SWA743/history/20200531/...

That's all got nothing to do with why GA is irritating. GA is irritating because their little mosquitoes are low and slow and have piston engine sounds and their pilots have a tendency to loiter.

For commercial flight paths, talk to the FSDO.

I live under the Seatac landing pattern. The noise that bugs me are the leafblowers.

Or maybe people could stop buying houses next to an airport that has been around for 80 years and arriving surprised that people fly airplanes around airports.

Not true; the only aircraft that does what you describe is a glider. Any propeller will generate a lot of noise, the tips of the blades get close to the sound barrier. Disclaimer: pilot here, I did fly gliders and I fly propeller planes regularly.

Well, even in a glider all the air moving by does quite some hissing, so its not completely silent (judging from the two flights I took as a passenger in a Blanik and Super Blanik respectively). Still much quieter than a small prop aircraft & you can talk with the pilot just fine.

On the other hand from the ground - yeah, a glider is pretty much silent. You might sometimes hear some rather earie whistling from some types when they are directly above, but thats it.

He said the wind is the only thing you hear. Yes, in a glider you hear the air moving, but adding a propeller adds a huge amount of noise over that base sound.

I love the sound of airplanes and all things airplane related. I think you may have just given me a great tip as to where to buy real estate. Thanks!

For all that you read about people complaining about airplane noise, I grew up only a mile or two from an airport and never thought about it nor do I remember anyone else complaining. But one of my recurring dreams/nightmares for most of my life is of watching a plane overhead and realizing at first something is wrong and then that it's going to crash in the back yard.

That price differential can make a lot of soundproofing worthwhile.

"The weight of the batteries makes swapping infeasible" comment makes absolutely no sense. Make them modular, In sub units which can be handled, mount them at the right points for C.G and design an airframe to permit module swapping with suitable equipment.

This, by the way, has to be the future of electric ground vehicles too. A standardized external battery format, automated/mechanical battery replacement. In theory "filling up" vehicles like could be quicker than refilling a fuel tank with gasoline or diesel.

And to ensure that I get marked down, I'll add that I'm fairly certain that only government(s) can make this happen (enforced standardization of the form factor across the industry).

People keep saying this but it never gets more practical. Meanwhile, battery ranges get longer and recharging gets faster. I'm not convinced that swappable batteries are the future of EVs at all.

Where battery swapping was used, in forklifts and other indoor handling machinery, it seem to be on the way out. Newer forklifts tend to use lithium-ion batteries. "Lithium-ion forklift batteries can be opportunity charged in any setting, eliminating the need for time-consuming battery swaps" - Toyota. Swapping half-ton battery lead-acid battery packs was a headache. Unless you run 24/7, it's easier to just plug in the forklift when you're not using it.

Battery swapping was a bet against battery energy density getting better. Better Place, the auto battery swap company, lost that bet. (They were 90% hype, 10% about actually doing it, but that's another issue.)

In addition, charge time is pretty much irrelevant in all applications except long distance road trips. The typical electric car uses 15-20kWh/100km. A car spends more than 20 hours a day parked and almost nobody travels more than 100km a day regularly. Charging at low single-digit kW as you can get from a normal socket is sufficient. For the rare trips that exceed normal battery capacity you can just rent a plug-in hybrid or deal with a small number of 45 minute breaks while you super-charge. Or take a train.

In the western US (at least), although most car journeys are short and daily charging makes the most sense, not being able to use a single vehicle for longer journeys without enforced long-ish breaks currently acts as quite a deterrent to the all-electric car vision of the future. Currently, with gas/diesel vehicles, the same car can function more or less equally well for just about every type of journey, and it has long been a dominant habit of the US consumer to target what they perceive as their most demanding use. In the US, at least, one version that most demanding use is "driving for two days or more".

I love trains, but train travel across the western half of the US is a joke, and isn't a lot better in the eastern half. When the train can take you, it's great - we used it to get from Santa Fe to Chicago last thanksgiving. But change the destination or origin just a little bit, and it becomes almost absurd to thiking about using it.

Only a tiny percentage of cars in the US are used in this manner though. You're talking about the long tail, and yes, the long tail will take longer to be served. More supercharger stations out there would go a long way though. You charge a lot during the duration of a simple rest stop and meal break.

I guess rural locations have a harder time. Maybe once we replaced all cars in cities with electrics we'll have something figured out that helps people who really need 800km of range.

Agreed. With the rate that batteries are improving, in the not-too-distant future range will no longer be a problem for the vast majority of the public.

I feel like both would be useful, given that batteries typically have a limited lifetime and I'd rather not have to tear apart my car to replace them when the time comes.

That's a huge difference in frequency though, once a week for a daily recharge vs once per decade. For the latter, it can take a few hours of labor and a lift to do the swap-out and it's not a meaningful difference, and ends up being cheaper overall than designing the whole battery system to be modular and easily removable for something that will only ever happen once.

Plus, EV battery thermal management is getting better and better. Most EVs won't ever have their battery pack replaced, just like most ICEs don't ever have their motor/transmission/etc replaced. It doesn't make sense to optimize for ease of replacing those on an ICE and it similarly doesn't make sense to do so for a battery pack on an EV.

> For the latter, it can take a few hours of labor and a lift to do the swap-out

Only if it's a giant monolith. Smaller modules wouldn't have this issue, especially if accessible from, say, removable floor panels or somesuch.

(Hell, you could have both - a giant monolith that you could replace all at once from below, or individual modules you could replace one-at-a-time from above)

> for something that will only ever happen once.

Will it, though? Like, battery technology will (hopefully) continue to improve, in which case there will always be a desire to upgrade to the latest-and-greatest, preferably without tacking on a bunch of labor costs (or else keep said costs to a minimum; user-swappable batteries make things easier for the repair shops, too). And damages could still happen, necessitating replacement (particularly partial replacement; it would suck to have to remove, replace/refurbish, and reinstall the entirety of the car's power storage just to fix one cell).

> just like most ICEs don't ever have their motor/transmission/etc replaced.

Usually because most people write them off and sell 'em to Pick N' Pull when that happens, not because internal combustion engines last forever. Personally, I'd prefer my cars to not be disposable.

People don't make these kinds of upgrades to cars. They just buy new ones. Your suggestions don't jibe with the real world and consumers' revealed behavior.

> People don't make these kinds of upgrades to cars. They just buy new ones.

My point is that's a problem, and that we can and should fix it with electric cars instead of continuing to boneheadedly allow that problem to persist.

There are, on that note, plenty of people who do rebuild or even replace the powertrains on their ICE-powered vehicles. Quite a few people do it out of necessity (a new engine is cheaper than an entirely new car, even with labor factored in, unless the designer has specifically made the car hostile to aftermarket servicing). Quite a few others do it for fun (e.g. hot-rodding, "ricing", etc.). Some people are even converting ICEs to EVs (I'm considering doing this should my car's engine give up the ghost).

> Your suggestions don't jibe with the real world and consumers' revealed behavior.

"consumers' revealed behavior" is a product of what's available on the market, and at what cost. If an electric vehicle with user-replaceable batteries exists, people will absolutely buy it. Upgrading those batteries will almost always be cheaper than buying all those batteries plus an entirely new car around them.

Flying is a fully regulated industry worldwide. Modular industry standard swappable batteries are achingly simple but so is regulated seat pitch and look how likely that is.

Food cards? They did that. Intermodal containers? They did that.

I like the idea of swappable batteries. I don't like the idea of taking someone else's battery in whatever condition it's in vs only using my own supply of swappable batteries.

It's not unlike propane tanks for a grill. You turn in your tank and get a different, filled tank.

Except for the part where batteries are chemical processes that can deteriorate when poorly maintained. Just look at how people abuse rental cars (e.g. Clarkson’s “Fastest car in the world”).

Then there’s the added issue that if you get a dud gas tank, the worst thing that happens is that it leaks and you bring it back after letting it empty overnight in the garden. In this case, a battery catching fire would be near to guaranteed death for anyone on the plane.

I don’t even lend 18650 cells to friends for this exact reason, let alone strangers.

I admit to not knowing a lot about battery tech, but how exactly does a driver of a vehicle abuse the battery? Isn't that a function of the vehicle design rather than behavior by the driver?

I would be alright with it if I didn't have to buy a battery with the car.

> A standardized external battery format, automated/mechanical battery replacement

Nio does this with their EVs:

https://insideevs.com/news/426014/nio-power-battery-swaps-50...

https://www.topgear.com/car-news/big-reads/power-shift-batte...

The idea is the easily replaceable pack gives you the option to charge, swap, or upgrade the battery as you like.

So did Tesla and Better Place. Neither do anymore.

Did either one get to 500,000 battery swaps as Nio has done?

As I noted, this is only going to work when the batteries are as cross-vehicle as current gasoline pump nozzles. And I would wager that this implies government action (or at least, the threat of government action) to bring about.

It's not useless to do it on a smaller scale, but ultimately until you can just drive into what used to be just a gas station, put your car over the designated spots and in 20 seconds your battery is swapped out, then its still not a serious replacement for oil-derived liquid fuels.

> this is only going to work when

It's working right now. They've done it 500,000 times.

You're being needlessly pessimistic. Battery swapping is simply an option they offer. You can use it or not as you like.

it's such a good idea you can raise almost $1B, get a car manufacturer to build a car for you supporting this system, convince a country to be a guinea pig, and ???

https://en.wikipedia.org/wiki/Better_Place_(company)

>>In sub units which can be handled, mount them at the right points for C.G and design an airframe to permit module swapping with suitable equipment.

Swapping out stuff like that is going to be tricky. These are essential pieces of equipment. Whenever you plug/unplug important things from passenger aircraft you have to check and doublecheck that they are installed properly. You have to test them. Swapping out batteries would be like installing a new fuel tank. Swap and go may work for cars, but a faulty connector on a plane;s battery could mean the flight ends in flames.

> design an airframe

There's the problem for this plane, they were using an existing airframe. Which looks to me like it really needs the weight in the front third to balance that ungainly long passenger cabin, so I bet the batteries are in the long forward section.

And a Caravan is probably the best candidate for a battery swap system. Many of them come outfitted with a large underbelly cargo container.

While you are not necessarily wrong, such a system would add complexity and currently they don't seem to need it to be competitive, so why bother? It is the kind of innovation which will come if the flight type becomes sufficiently common.

Electric planes with swappable batteries exist:

https://en.wikipedia.org/wiki/Pipistrel_Alpha_Trainer#Alpha_...

I guess the use case is that a flight school could have 2 planes & 5 batteries, and get more student flights into a day by not waiting for charging. Operating from one fixed base, one owner, so no issue with getting someone else's pack. 126 kg, so not trivial to remove.

Personally I would rather wait 30 minutes for it to charge than try to replace 2,000 pounds of batteries.

Is there any room in the imagination for swapping these batteries mid flight?

I'd imagine it makes even less sense than mid-air jet-refueling.

I imagine it would be mid-air recharging instead.

Tracking with lasers should be manageable for low level flight.

https://en.wikipedia.org/wiki/Wireless_power_transfer#Lasers

From the article: "charging times correlate closely to flight times, says Ganzarski. That means the batteries would need about 30-40min of charging following a 30min flight. The weight of the batteries makes swapping spent cells for fresh cells unfeasible between flights, he says."

Does utilization for these short-hop routes correlate to this sort of down time?

It becomes more and more feasible the shorter the flight is, since the 'turnaround' time on the ground starts to become longer than the actual flight time. That's why Harbour Air, which operates ~20 minute seaplane flights from Vancouver, will probably one of the first airlines to operate electric aircraft in commercial service.

https://www.harbourair.com/about/corporate-responsibility/go...

It's probably longer than required for passenger flights. The Caravan is 9-13 passengers (depending), plus a little baggage. Wouldn't be hard to unload/load 10 people in less than 30 mn. However the question is how many small commuter airlines are operating a flight with repeated as-fast-as-possible turn around?

Cargo configuration, certainly seems like you could charge it faster than a load/unload.

The thing about fast turn around's is that planes only make money when flying. However a big part of flying is the expense of fuel. So if you can make your hour flight in $12 of electricity, that brings the cost way down. That offsets the cost of sitting on the ground for an extra X minutes.

Also gotta take into account the electric versions reduced need and cost of maintenance. So there is reduced aircraft downtime for less maintenance, and it costs less each time. Overall, that probably greatly increases the time available to fly and therefor the profit potential for the plane.

> Wouldn't be hard to unload/load 10 people in less than 30 mn.

Ryanair is probably best at it, executing within time above but in a 737. You can hate Ryanair for some things, but I admire for how affordable they make flying.

Darnit. I saw Grand Caravan and thought it was an all-electric minivan.

I've been waiting years for an electric minivan. The moment someone comes out with one, I'm turning in my current minivan, which I love, for an all electric van.

Like me, you can pin your hopes on the 2022 VW Microbus: https://www.caranddriver.com/volkswagen/microbus

Chrysler sells Pacifica Hybrid (which is actually a plug in hybrid, so pretty close to all electric in every day situations). 2021 Toyota Sienna is also going to be a hybrid (but not a plug in).

Yeah I looked at that Pacifica hybrid. Sadly the all-electric range is too small for our use case.

Didn’t know about the Sienna. That could be interesting. From what I understand the Toyotas are fairly hackable to turn them into plugin hybrids.

The all electric range is not a big deal in a PHEV. That’s what the gas engine is for!

But the whole point is to be more environmental. There is no point in getting a whole new car just to mostly use gas.

There is certainly a point for most people to use a plug-in hybrid if the price is not too high. Most trips are short. You only take long trips a few times a year. (or maybe a few times a month if you drive a lot, but that still equals most trips being short). Thus you have "infinite range" via the petrol engine and the vast majority of trips are all electric. This makes total sense.

If you're already getting a new car, it makes sense to get a hybrid. But it doesn't make sense to replace a working car to get a hybrid. It barely makes sense to replace a working car to get an all electric, but it makes sense if you have solar.

A lot of plug in hybrids have an incredibly short range. It’s not a bad idea, but many of the implications are due to fleet requirements not customer demand so they end up with sub 20 mile ranges when new and that drops quickly due the large number of charge / discharge cycles.

How can they get so close but then still miss the mark.

> I've been waiting years for an electric minivan. The moment someone comes out with one, I'm turning in my current minivan, which I love, for an all electric van.

Bad news: while you can still buy minivans, they're being phased out in favor of SUVs. Dodge just put the nail in the coffin for the Grand Caravan, and production stops this year: https://www.thedrive.com/news/33702/death-of-an-icon-dodge-g...

The investments are in the SUV/CUV segment where profit rates are higher.

Yeah I noticed that trend too. :( It’s a shame because we had both and the van is just so much easier for hauling 6 people than any SUV out there.

The Dodge Grand Caravan and the Chrysler Town and Country were the same vehicle with badge engineering. The Town and Country was replaced by the Chysler Pacifica in model year 2017, but they kept making the Caravans on the old design with Dodge branding for cost concious buyers. In model year 2020, (Fiat) Chrysler is renaming the low end Pacifica models to Chrysler Voyager --- it could easily have been called a Dodge, but I guess they're trying to clean up Dodge to be muscle cars and trucks, like Ford is trying to do with their line up.

> Dodge just put the nail in the coffin for the Grand Caravan

Its replacement is the Chrysler Voyager (another miniman, same parent company, different brand), not an SUV or CUV.

The Grand Caravan interior was from 2005. It was showing its age. Also why make a minivan that sells around 30k when you can make an SUV that sells for 50k. It makes me sad but that is capitalism for ya.

Same.

The Model X gets pretty close, but is way too gimmicky with it's touchscreen everything and cutesy doors.

A modern minivan is already the most sophisticated vehicle on the road. I just want one in electric.

The Model X sadly does not have nearly the versatility of my Honda Odyssey.

And it costs an extra $100K. :)

The model X is more expensive, but it’s not $100K more than a new Honda Odyssey. Heck, it’s not $100K more than your current Odssey! The X starts at $80k, while the Oddysey costs somewhere between $30k and $45k.

It’s only the top of the line performance trim that costs $100K.

Maybe I’m misremembering but in 2017 I think the maxed out Model X was $138,000 and my Honda was $45,000, so almost $100K difference.

I believe you’re right, prices appear to have dropped.

I don't know about the US, but here in the UK, the word "caravan" does have negative connotations for a lot of people. It conjures images of ungainly and flimsy caravans pulled by cars [0]

[0] https://images.app.goo.gl/Lg62ijPT1Bt9apNeA

Toyota, out of all companies, is planning on releasing an electric Proace:

https://www.autoevolution.com/news/new-toyota-proace-ev-sche...

Not exactly a minivan and probably won't reach the US, but it's a start.

At least they’ll prove it makes sense! Maybe it will motivate Honda to do an electric Odyssey.

Those kind of vehicles are fairly popular in Europe.

Ford is launching an electric Transit at the end of 2021 ('22 models.) We have a larger family, so we're hopeful the range, power and cost will be acceptable. Swapping out low MPG large commercial and passenger vans for electric will prevent a lot of gasoline and diesel usage.

Unfortunately this model is available only in Europe

Supposedly it will have a US launch in a couple of years. We are disadvantaged against the Transit’s relative popularity in Europe, though, so it’s possible they will not see it through.

It's not just "popularity" - EU govt is subsidizing EVs big-time (tax breaks) to where all available EV capacity is going to Europe for many car manufacturers.

>> current minivan

"Current" would actually be a good model name for an electric vehicle.

On that theme, there was the Chevy Volt... but I don't think Resistance would be a good choice.

Watt!?

I would totally drive a Honda Current.

Especially an electric boat.

Nissan had one since 2012, but only recent oneS have reasonable battery sizes

Apparently not here in the US. :(

Mercedes-Benz are currently launching the EQV minivan.

Unfortunately the real limitation here is still weight. You can get excellent torque and incredible reliability from electric motors vs. gas powered engines but the biggest difference is that as you fly longer the plane gets lighter with a gas powered plane. With an electric plane you're always at full weight and that limits your flexibility.

Worse, batteries are still very, very heavy compared to the energy they store. I suspect that as battery technology improves we'll see a drastic shift toward electric planes being more appealing.

For GA aircraft they'd be amazing. Excellent power, significantly higher reliability, much lower maintenance costs, and much lower cabin noise. But at the weights listed, I can't imagine a Cessna 182 going electric anytime soon.

There have been some drones and experimental air vehicles where quadrotor-type electric props do the VTOL operation, and then a fuel-powered propeller and wings take over for efficient forward flight. This is one way to build a VTOL drone with serious range. (This is a big deal for the military, where limited range means fighting for and holding a string of bases to get to the area of interest.)

It seems wasteful to carry both systems, but it's simpler. The mechanical complexity of transition-type VTOLs is far worse. See the Osprey.

> Worse, batteries are still very, very heavy compared to the energy they store

Lithium-Sulfur batteries will help here. They have a higher gravimetric energy density than other battery chemistries. The main problem with Li-S batteries is the poor cycle life but progress is being made in improving that:

https://www.monash.edu/news/articles/supercharging-tomorrow-...

Regular 208 spends 150 kg per hour, which is microscopic by aviation standards. A piston An-2 spends the same, but in super expensive avgas, and flies half as slow. A more comparable DHC-3 flies a bit faster, at 135 kg per hour, again, avgas.

1000 kg of LFP cell will hold you in the air for just 20 minutes

Given that the useful load of a 208 is around 1500kg, 150kg/hour is by no means 'microscopic'. Yes, obviously compared to a 787 which burns 5000kg/hour it's a different story. But the useful load of a 787 is also much, much higher.

“Super expensive Avgas” — in Europe definitely, but in the US, JetA is pretty close in price. At Palo Alto Airport, full service 100LL is $4.15 per gallon and JetA is $3.44. In Europe, I think 100LL is something like $15 per gallon or thereabouts. Europe has managed to decimate general aviation compared to the US.

it varies a lot in the US. Signature at KOAK is around $8/gallon.

Doesn't a full battery carry more electrons and is therefore heavier?

No. Aside from the fact that the weight of the electrons, although not zero, is negligible, they also don't get "lost" in the process... they just get moved around, in the case of battery power literally from one end of the batery to the other. Combustible fuel in contrast, gets turned into gases (CO2 and H2O) which are blown out the exhaust and thus lost.

Yes. A small amount. A 100kWh Tesla battery has 3.6e+8 Joules of energy. E = mc^2 tells us that the mass of the stored energy is 4e-9 grams, so 4 nanograms.

No. The number of electrons does not change. Instead, the different configuration causes a slight fluctuation in the mass of the atoms.

I wasn't referring to parent's suggestion that the number of electrons changed, of course, you're right, it doesn't. Just that the weight does in fact change.

> I wasn't referring to parent's suggestion that the number of electrons changed

So help me out here, am I missing something?

It's a two part question, and only half a part is actually true. "more electrons" is false, and "therefore" is false, but "heavier" is correct.

In that situation, I think an unqualified "Yes." is extremely misleading. So I wrote "No." as the lead-in for my comment.

Is that super rude? Am I completely wrong, and an unqualified "Yes." is actually appropriate here? Is there some other reason for me to get multiple downvotes for my post?

If I'm doing something wrong, I'd like to correct it for the future.

Think of it like a mousetrap. Two energy states, same mass.

Yes, as it follows E = mc², but it would be so incredibly tiny that a speck of dust would weight more than the difference it would make between charged and discharged.

If this really represents (in general) the weight and efficiency you're going to get, then electric planes of this size will have to remain a specialized niche for only certain kinds of rare flights.

At 100 miles max range, the people would be better off driving, unless you're talking about mountainous or water-crossing flights where there is no alternative. (plus think about the added overhead of getting to/from airports, etc)

You have to wonder why they chose a 208B -- when you would generally try for the smallest and lightest plane to start with. Answer: because they can't fit enough batteries in a smaller Cessna to get it to perform on a reasonable flight. The ideas elsewhere in the thread about having electric planes lower the cost of training flights, etc. won't work if you need a bus sized plane to hold the batteries.

The plane has to be half empty, and even then can only eke out 100 miles. That's like a half hour of flight. A $2-3M plane can only handle a 1 hour ~50% duty cycle, max? That's not gonna...fly.

I'm not intending to sound discouraging, and it's an interesting demonstration, but fundamental energy density of battery chemistry is a bitch.

Edit: why, for the love of god, would they include that ear-destroying audio with the showcase video clip?

IMO this comment is pretty short-sighted.

Gravimetric energy density of batteries tripled between 2010 and 2020 and in the same time period cost went down 87% [1]. By 2030, this plane could easily have a range of 300mi.

[1] https://cleantechnica.com/2020/02/19/bloombergnef-lithium-io...

I seem to remember being referred to as "that battery guy" here on HN, so here I am I guess.

Unfortunately that is complete bullshit. (No offense intended to the Bloomberg suit.) Energy densities have absolutely -not- tripled since 2010, in fact they have barely changed. Costs have gone down, yes, but not by 87%.

Cost-wise: a simple counterexample is to look at any smartphone BOM from 2010. Phone batteries around 10-12 Wh cost around $5. That's somewhere around $416-$500 per kWh. And that's for a phone battery, AKA not exactly the cheapest batteries out there, and not at massive scale (phone batteries are tiny in capacity and almost all 2010 smartphones sold in the single-digit millions max.) Currently, as Bloomberg claims, cheap batteries are around $160/kWh. So that'd be a change of around 61% cheaper. Around 0.4x the 2010 price instead of the outlandish claim of 0.13x the price. Keep in mind that this I'm just basing this off mobile phone BOMs cause I can't be bothered to find anything cheaper - there certainly were cheaper batteries then.

Energy density wise, it's even more bullshit. TRIPLED? No, energy density has sat around 200 Wh/kg for approximately forever. (Off the top of my head, since at least 2009.) 200 Wh/kg batteries have been available to the -consumer- at not-insane prices for over a decade. In 2013, anyone - business or consumer - could purchase Panasonic cells at 224 Wh/kg. Today, the highest energy density anyone claims is around 240 Wh/kg from Tesla's 2170. Let's take that at face value and assume it is 240.0 Wh/kg; that's a 7% increase from 2013, and at best somewhere around a 15% increase from 2010.

The sad reality is that batteries are extremely hard, and few things have changed aside from price. Hell, even the form factor, the 18650, was invented about three decades ago! Pretty much the only thing that has changed recently is that volumes have gone up massively, driving down costs with at-scale manufacturing. But that has happened in the vast majority of industries, and was entirely predictable. Furthermore, the cost decrease for batteries specifically hasn't been as fast as nearly everyone predicted. All the other magical headlines, about energy densities skyrocketing, or fancy new chemistries, or swappable packs, have been pure bullshit.

I'm glad the above comment got some attention even buried here :) Another comment I'd like to make: Even with that increase, say 200 Wh/kg in 2010 to 240 in 2020, a lot of these higher-energy-density batteries are more expensive/easier to damage/have bigger heat management problems/etc. Keep in mind that is the raw cell weight. At 240 Wh/kg, you do not have any cooling, casing, wiring, BMS, safety systems - that is a plain cell in a vacuum. Once you've got all those goodies around the battery, even if you're best-in-class like Tesla your total energy density is around 150-160 Wh/kg. If you aren't making a luxury vehicle, you might end up around 80-90 Wh/kg (24kWh Nissan Leaf battery is in total 82 Wh/kg), and even if you do aim for something light and use fancy engineering you might end up around the 130 Wh/kg mark (2019 Audi e-Tron: 134 Wh/kg.)

Batteries are hard.

Do you happen to have sources / further reading on this?

I didn't bother to give sources because everything is pretty trivial to find, but you can Google "tesla 2170 bench test" or "Samsung INR21700-50E bench test" for details of the best cells today, "history of 18650" to see that the format is nearly 30 years old, and "(your favorite 2010 phone) BOM" for some example price data. (as an example: galaxy s4, $5 and 10Wh.) That said, I'm positive there were cheaper batteries at the time, given that cell phone batteries are typically more expensive to make even today and are on the order of 10,000 times smaller than car batteries.

I wish I had some quality further reading to link, but unfortunately I don't. "battery Google" is dominated by 1) overpriced e-stores selling a few cells to vapers, 2) news about handmade cells in a lab reaching some ridiculous performance (yeah, and a handgun kills cancer in a lab), 3) complete unadulterated bullshit from the news/bloggers/social media about battery trends, 4) bullshit corporate PR of companies claiming they're a year away from 900 Wh/kg (anyone working with batteries would give their firstborn child for 900 Wh/kg no joke)... Sadly, it's a mess. The other problem is that an explanation is hard - very hard. It involves manufacturing (and scaling this), thermal properties, funding for research, an analysis of the players in the game, etc etc. I have considered writing one, but it even for me it would be quite a project and even posted here on HN I have a feeling it might fail to get any attention. Nobody wants to read a complex multifaceted failure analysis, everybody wants to read a Bloomberg headline saying we're racing into the future, even if it's total bullshit.

> I didn't bother to give sources because everything is pretty trivial to find

If it was then I wouldn't be asking :)

Best I was able to find was a chart (ostensibly from NASA) comparing different battery technologies, which is probably where the 3× claim originated, but doesn't say much about improvements over time (only by technology): https://www.epectec.com/batteries/cell-comparison.html

To your point, though, it does indicate that lithium-ion specifically hasn't had such a 3× jump (but it does represent such a jump relative to older technologies like lead-acid or nickel-cadmium).

> you can Google "tesla 2170 bench test" or "Samsung INR21700-50E bench test" for details of the best cells today

That doesn't really say much about historical trends, but good to know.

> "history of 18650" to see that the format is nearly 30 years old

Is that relevant? AAs are even older than that, and yet seem to have improved quite a bit.

> and "(your favorite 2010 phone) BOM" for some example price data. (as an example: galaxy s4, $5 and 10Wh.)

That does line up with https://www.androidauthority.com/galaxy-s4-bill-of-materials... (which cites $5.60 for 2600mAh, or $4.90 for 2100mAh).

Meanwhile, the Galaxy S9+ lists $4.90 for 3500mAh: https://technology.informa.com/601100/galaxy-s9-materials-co...

Neither of these really say much for the mass, though, so it's hard to get a clear picture on energy density from this.

> Nobody wants to read a complex multifaceted failure analysis

I mean, I would, but I'm well aware of my insanity.

There is a physics problem with carrying both fuel and oxidizer and not dumping spent fuel into the atmosphere. I suppose one could use lithium air batteries and then land heavier than takeoff.

The reason petroleum fuel works so well is because you scavenge 2/3 of the fuel from the air.

This is an underappreciated factor, particularly for long-haul flights. For transatlantic/transpacific flights the fuel can be over a third of the total takeoff weight of a modern airliner. Burning that mass off as you go means you get more efficient the longer you've been flying.

Even if/when batteries match the energy density of aviation fuel (appropriately adjusted for motor/engine efficiency), they will still be at a substantial disadvantage for long flights.

The efficiency is worse the further you go, because you have to burn extra fuel just to carry extra fuel the whole way, so that it be used for the incremental distance travelled. It's why the A340-500 flying gascan is such a disaster from a unit economics perspective. It's also why Emirates, Etihad and Qatar did such good business for so many years connecting east and west with a stop in the Gulf as compared to eastern and western carriers who had to go the whole distance without stopping.

That's a different efficiency comparison.

You are correct that for a given type of plane, efficiency is worse for father distances. When comparing battery vs. hydrocarbon-fueled planes, however, hydrocarbon does relatively better the longer the distance, for the reasons discussed above. Battery-powered planes may soon be practical for regional short-haul flights but they're not going to be competing on transatlantic routes anytime soon.

It's not a problem per se, but it is of course a factor.

On the other hand, the thermal efficiency of driving an electric motor from a battery is ~99%. The thermal efficiency of jet and propeller planes is in the mid-30s.

A long haul jet is at takeoff roughly evenly split by weight between fuel, passengers, and plane. Yes, it becomes lighter, but the more importantly it scavenges it’s entire takeoff weight in oxygen which conventional lithium ion batteries can’t do. Lithium batteries have improved, but you have to carry both sides of the redox.

The only way I can think to get similar physics is to use lithium air batteries and then dump them with a parachute when discharged.

That's not the point of the comment you replied to.

Pulling in oxidizer from the air gets you a 3x efficiency boost, but using a combustion engine has a 3x efficiency penalty. It cancels out.

Above all, the plane, and especially something like Caravan needs to be cheaaaap.

Planes like DHC-3, C208, PC-12, An-2 are all utility aircraft above all. They are sold, and resold until they can't fly, and then they get cannibalised, rebuilt, and made to fly again, and when nothing would really be left of the plane, it will be sold to places like Africa, or Latin America.

One of the biggest problem for makers of such aircrafts is the second hand market getting too big.

There is zero demand for brand new An-2s, but the second hand market is surreally big. Same for DHC-3, Caravans, and Pilatuses seem to be joining that category too soon.

> Above all, the plane, and especially something like Caravan needs to be cheaaaap.

Sorry, commercial aviation is an expensive game with no cheap options.

- Cessna Caravan new $2.3 million

- DC-3 Reman (Basler Turbine) $8 million, used (piston) $300-000 to $1 million (bargain in the cargo business)

- C-130/L-100 new $70 million

https://en.wikipedia.org/wiki/Basler_BT-67

https://en.wikipedia.org/wiki/Cessna_208_Caravan

One derelict DC-3 was repaired from a hull to flyable using $85,000 in donations by Plane Savers using donated labor from a school, so that's about the price floor:

https://www.youtube.com/watch?v=8haGfVvcS0I

The Basler Turbine DC-3 is a from-the-sheet-metal up reman, and the airframe is expected to last a total of 150 years. (Since the DC-3 is not pressurized, it has not lifetime age limit.)

I could see this working out for the skydiving niche market.

They do lots of very short trips, and the space required to move around for the jump means the smaller seating capacity isn’t horrible.

Even as I bet against electric flight being commercially feasible except in extremely limited conditions, I'm excited by any news that I might possibly be worng.

Only 6 months after the first commercial airplane electric flight. https://www.harbourair.com/harbour-air-and-magnix-announce-s...

I'm not sure people will be as ready to go back into 200+ passenger aircraft as before.

Small party flights could become more popular as the range goes up.

There's a very long way to go before safety is comparable. Last time I looked into it, you have better odds skydiving from a small plane than landing in it.

Most small aircraft accidents are completely preventable loss of control (either by taking off with too much weight, stalling during takeoff, or stalling during landing) or flying into IMC (instrument metereological conditions including clouds, fog, etc.) and becoming disoriented and losing control. Simple engine failure is something that every private pilot trains for.

Improvements in training can significantly help with both. Instrument training in particular drastically reduces the risks of inadvertent IMC. Some technology also assists with the latter (eg; synthetic vision on foreflight on aircraft with garmin G1000 cockpits gives you references for how the plane is positioned and any terrain around you you could hit).

Not at all, skydiving from a plane without a parachute is almost always deadly (very few exceptions) while landing with an engine failure is something every student practice in the flight school (at least in my country).

The smaller the plane, the easier to land it with an engine failure, the smaller the plan the fewer pieces that can break. yes, the average General Aviation pilot is quite bad, that explains the huge accident rate compared to airliners, but the reliability of the planes is not bad at all.

That's why I like gliders - one less component to fail (the engine) and every landing is an engine out landing, with the plane built and pilot trained to do that. :)

All pilots are trained to land with the engine out. Some are better and most are not, that's not the plane's fault. Yes, glider pilots are the best at this :)

I think they will. We won't be back to "normal" that soon, but when we are, it will be amazing how much we've forgotten about the recent past. We're usually living in the now, not in the past, and adapt and will fall back into the same patterns.

Very impressive

The Grand Caravan is one step up your average "learner aircraft" and IIRC it's a turboprop (not a piston engine as most basic aircraft)

> As configured, the Magni500-powered Grand Caravan can carry 4-5 passengers on flights up to 100 miles, taking into account the need for reserve power, says Ganzarski.

Not bad, not bad at all

Now a compact fast-neutron lead cooled reactor would come in handy... development has been done..like the Convair NB 36H, but with 1950 tech..I wonder with modern specs and upgraded safety protocols..

The Convair NB 36H wasn't actually powered by the reactor, though; its sole job was to validate that it was possible to shield the crew from the reactor's radiation (which it did).

However, there were certainly successful tests of actual nuclear-powered jet engines, like General Electric's X39 (a modified J47, and slated to be slapped onto that NB 36H to make a Convair X-6) and J87 (a different design for a different nuclear-powered bomber project, the WS-125).

A key issue is the shielding necessary to keep such an aircraft from irradiating everything around it (you think neighborhoods bitching about nearby airports are ornery now...); that shielding is heavy. Accidents also make such craft much riskier, which is indeed a cited reason (other than costs) why the USA and USSR both cancelled their nuclear-powered bomber programs.

As a workload it sorta makes senses. You want raw output for take-off and then steady efficient power for cruise. Both of which electric motors can do.

...just a question of battery weight, which is dropping

Piston engines can also do. You want max output for take-off, but to maintain the cruise speed you need around 75% of the engine output and you fly at "steady efficient power" (75%) for cruise; there is no difference here. It's not like cars where you brake and accelerate many times.

This is amazing for rural communities and student pilots. And if it became safely possible to run the plane with just one pilot onboard for commercial service, this lower cost plane would have even more potential.

Up to 40 minutes for charging could be an issue for airlines who want to turn planes around quickly, though I doubt Cessna operators are striving for Ryanair economics yet.

The number of pilots has no correlation with the electric propulsion.

For student pilots it is not amazing, in the flight school you need to do a raid (this is how it is called on this side of the ocean) flying between 3 cities and 500 miles minimum; you cannot do it with the electric plane and as a student you are not good enough to fly a different plane model (with ICE power plant) just for the raid, so you cannot complete the school.

You'll still be able to do most of your pattern work and general handling training in vastly cheaper electric aircraft.

Then what do you do, transition on a different plane during school? At that point you will need a full 45 hours or more on the second plane, negating the cheaper first plane.

No you won't, there's no requirement to do the 40 hours for a US private pilot certificate in the same aircraft type.

This is what it takes to learn to fly a plane; if you want to learn to fly 2 planes in the flight school, you cannot do it in the regular 45 hours, it will take you over 60 hours if you are good, over 80 hours for most people.

I flew multiple aircraft in the same class and category while doing my PPL and had no problems. At this point there's old enough that's there's nearly as many differences between two C-172s as there are with a C-172 and a PA-28. Yes, it took me more than 40 hours but I blame that on scheduling, not the aircrafts.

I think if you were able to get the range up to 250-300 miles that would be a very big deal for far flung communities. All of those are underserved by air transport. Offhand thought is you probably could justify small pilotless freight aircraft.

First thought seeing this was of the Dodge Grand Caravan minivan we had growing up.

It's interesting how often names get reused.

Funny enough, there are all-electric versions of those, too: http://www.evalbum.com/2403

Is it any quieter than gas engines? Last time I flew in a Cessna, the propeller was bone-jarringly loud.

I’m skeptical about the $6 of electricity for the 30-minute flight, or at least want to see the assumptions there.

Even at super cheap $0.06/kWh rates, and 100% plug-to-motor efficiency, that’s only 100kWh. For a rated power of 560kW, that suggests an average power setting of around 35%.

$0.06 isn't super cheap for commercial electric rates, even in the US... for that, you're looking around $0.01-$0.03.

. . . average power setting of around 35%

That actually sounds about right. You only need full power for take-off.

EDIT: Thanks for the corrections.

Like the others, I’m also a pilot and confirm that we cruise in the 65-75% of rated power range in piston ops. Turboprops do have a larger power reserve / larger spread between rated and cruise power, but it’s nowhere near 25% in cruise.

How much would that change if you had a possibly lighter engine, and an empty hull (all extra weight disposed off)?

It’s only on max range flights that I throttle back as my airplane gets lighter. On typical flights, I instead take the 3-4% speed increase as the fuel burns off.

Lightness is a hugely important feature in airplanes. I’m not sure that current battery tech is poised to deliver on lighter aircraft for a given mission range. An additional drag (pun intended) for electrics is that landing weight is the same as takeoff weight except for skydiving ops.

As a pilot, I fly full power at takeoff, of course. In my usual piston plane, I fly at 75% power until it cannot maintain that power (due to normal aspiration and no boost from, eg, a turbocharger), and then "flat out" beyond that.

I do not think I have ever flown at 35% power except in the short time between final and touchdown.

It happens to fly low power, but only in rare occasions. I do that when I cross the mountains and I reduce the power while loosing altitude from ~ 10k to 200 ft at landing. The longest I flew with the engine turned off was ~ 30 miles, that was in a motorglider with the propeller feathered. These cases are so rare, but still exists.

At the risk of sticking my foot in it even further . . .

I fly at 75% power until it cannot maintain that power

Does that not mean that you are actually flying at well under 75% of the rated power even if it is the maximum power available at that altitude?

Yes, though normally aspirated pistons typically stay under 8500 MSL and very rarely exceed 12500 MSL. IIRC, you can make 75% power unboosted through around 7000’ MSL. I’d guess at least 90% of normally aspirated flight is under 7000’. It certainly was for me, even though my previous airplane could climb higher, it was slower up there, so I rarely flew it over 10K unless there was a screaming tailwind up high or terrible turbulence down low.

If I looked over all my engine monitor downloads for power settings under 35% while airborne, I bet the average would be under 1 minute per flight and it would be between 200’ and landing.

That is ridiculous - you wouldn't carry the weight around for that power level for such a short flight segment need. If you are averaging 35% power you have WAY to big an engine in your plane!!

Electric motors are very cheap and light for a given power output, especially for forced air cooling, so oversizing them doesn't impact the cost or weight too much.

They might use that fact to oversize them giving better redundancy (eg. one can fail during takeoff and it not be an issue).

In aviation where every kilogram matters and where you can put more batteries instead of an over-sized engine, that logic does not work. There is zero redundancy from oversizing the engine.

I think they meant that you can have engine-out during takeoff in a twin-prop, as long as you can steer against the prop's torque. It also gives you much steeper climbs, which is highly beneficial, particularly in some mountainous regions.

> particularly in some mountainous regions.

Yep. I lived in Truckee for awhile, and the local airport there is notorious for pilots making "unexpected landings" into the mountainside right after takeoff because they didn't climb fast enough.

not even close.

Piston planes cruise at about 75% rated power (engine manufacturers do not suggest running engines beyond that for extended periods of time). Jets closer to 90

Jets typically can’t make 90% power in cruise and are often flying at 50% or lower fuel flows than takeoff. (You might be setting almost 100% N1 speed as your power setting, but that’s not the same as setting 100% actual power in a jet in high-altitude cruise.)

Fuel flow is a good proxy for power. From the Citation II flight manual: max cruise thrust settings (104% N1 over 25K feet) have a peak fuel flow of 1716 lb/hr at 15K feet vs 1083 lb/hr at 35K vs 721 lb/hr at 43K ft. Sea-level takeoff fuel flows are not given in the manual, but are around 2000 lb/hr, so typical low 30s cruise flight is 55-65% power.

That may be cheap for residential, but commercial and industrial rates are much lower. $.015 isn't uncommon.

We have numbers for https://en.wikipedia.org/wiki/NASA_X-57_Maxwell

> maximum flight time of approximately one hour.

> 47 kWh (170 MJ) battery packs weight 860 lb (390 kg) for a 121 Wh/kg density.

47 * 0.06 => 2.82

Probably a better way to estimate battery capacity is through weight. The article says that the battery weighs "roughly one tonne", and li-ion batteries weigh between 150-200 wh/kg at the pack level, so the battery is probably between 150 and 200 KWh.

How much further could an ePlane fly if it was possible to discard spent batteries? (Serious question)

The Cessna 208 Caravan has an empty weight of 2,145 kg. The article states the battery is roughly 1 tonne (1,000 kg). One could assume the electrified version is slightly lighter, sans batteries, empty due to the lack of need for a lot of the gas related items.

So if the plane is now somewhere in the range of 3,000 kg at takeoff, clearly shedding up to 30% of the planes weight would allow it to fly quite a bit farther. That's one of the advantages of gas, as you burn it, you get lighter, you get more fuel efficient.

In your hypothetical scenario, do you care whether the batteries are recoverable and reusable? If not, then you lose a lot of the benefit of electrification.

I did think about going to the kind of electrochemical reactions which might provide power to a motor. I believe the flow batteries are low power density binary fluid systems so not very flight suitable.

So then I went to ascent phase. Detachable battery with glide home. Keep smaller battery for controlled descent phase.

Imagine if there were large fields (or lakes) every few hundred miles designated as drop zones where huge battery packs would be parachuted down into and recovered every couple weeks, from cross-country commercial flights.

I'm sure there are a million problems with it, but you never know.

Or flying "recharge" stations where appropriately sized drones carrying a new set of batteries (not necessarily all of them) would dock with the aircraft, push the new batteries into a receptacle while taking the old ones on board, then separate from the plane and land to the closest ground station for recharging until next plane to service.

This is an interesting idea, but it would be most efficient if the battery drops were frequent. Maybe every few miles instead of every few hundred. Of course the more modular you make the battery, the more overhead you have in chutes, battery housings, etc.

I know next to nothing about aviation, but I wonder if a "hybrid" would make any sense for planes, or if you'd end up with the worst of both worlds?

...receives power from a 750V lithium-ion battery system weighing roughly one tonne...

It's like a giant flying battery with a few seats.

Wow, 2000 pounds of battery. About twice the weight of a Tesla battery. This suggests that a it could take perhaps an hour to recharge the battery for each 30 minute flight. This is just a guess extrapolating from the non-technical article.

a range of 100 miles with 4-5 passengers

where the kerosene-powered variant has about a thousand miles with ~7 passengers

You can carry 14 people in a typical Caravan EX.

Wow that's a strange choice for a name. Can't think of anything I'd less like to fly in than a caravan. Makes me think of boring trips and cheap flimsy tacky boxes liable to be blown away by the wind.

To resolve the confusion: that's British usage. In North America, the thing you're thinking of is called a "camper", and the association most Americans have with the word "caravan" is to a Dodge minivan.

> the association most Americans have with the word "caravan" is to a Dodge minivan

For motor vehicles, perhaps. In general if I'm thinking of travel in a caravan it's 19th century wagons.

If it's any consolation, the Cessna Caravan predates the Dodge Caravan by 3 years.

I don't know what a Dodge Caravan is specifically. This is what 'caravan' makes me think of though - https://www.practicalcaravan.com/wp-content/uploads/2018/02/... - not what you'd want to fly in!

this is what i was thinking

https://duckduckgo.com/?q=caravan+waggon&t=brave&iar=images&...

Why is everyone thinking of cars? There is a far more picturesque and older meaning of the word.

http://remarkablejourneys.com/wp-content/uploads/2015/09/Day...

Because of this: https://en.wikipedia.org/wiki/Dodge_Caravan

They were immensely popular throughout the 90s and early 2000s.

we drove a dodge caravan around the country a number of times while i was a kid.

To be fair, Cessna had the name before Chrysler co-opted it

Caravans have been a thing before either Cessna or Chrysler were founded.

Light aircraft aren't really known for having enlightening names.

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