To recap, based on financial statements the company:
used to be a "waste management" company that failed and was sold as a "public shell" to enable the formerly private company to go public and sell shares (the waste management business it was engaged in was an effort to commercialize a process to treat low-level nuclear waste developed by Russian scientists)
has $64 mil in debt apparently unrelated to aviation
has spent $3.8 mil on R&D for this project
has 8 R&D employees
only 2 of those 8 have any evident experience related to designing aircraft
So you need enough fuel (kWH in this case) for taxi, take off, the trip itself, divert to alternate airport, plus reserve for 30-45 minutes of holding, at least one missed approach/go-around, plus maybe more emergency reserve beyond that. It might add up to only 300-400 of practical travel range.
Another question might be whether or not the range can be extended when there are no passengers; a turboprop can be loaded with extra fuel when only the plane needs to be moved; the beechcraft super king (10 pax turboprop) has nearly a 2000 mile range with no passengers.
It was also slightly shady to specify the range in miles, when nautical miles are more typically used.
I’m curious what voltage the pack runs at and how long it would take to charge. Many of these types of aircraft operate in FAR Part 135 on-demand operations. Aircraft and crew utilization are crucial for the business model.
Expensive airplanes and pilots don’t make money sitting on the ground. Of course, if operating costs (fuel) are a fraction of a traditional aircraft then margins get better but do they get good enough to offset 2-3x more aircraft and pilots to operate those aircraft to be able to fulfill demand?
I hate to sound like the people who constantly naysay electric cars because of charging times but in this industry turn around time is crucial.
This is the number one question I had as well, for the same reasons. Porsche has a 1000V system in their new Taycan EV, so I'd assume they're at least at that level. At 900kWh, a system like that could charge from 10% (assumed minimum reserve) to 95% (Batteries are never really charged to 100%) in under 2 hours @ 400KW, which is about the power level of the beefiest EV chargers being developed right now.
More likely they will have swappable batteries, which makes a lot more sense from a thermal management point of view as well. You can either load up the pack with all kinds of cooling and deal with the added weight, or just make it passive air-cooled and swap it out between flights before it gets too hot.
Pipistrel Alpha, the only real production electric plane shipping, is using swappable batteries. There's really no other viable way with current technology to have reasonable recharge times.
There's no particular reason charging a big, multicell battery needs to bottleneck on a single charger. (is there?) It's done with cars for what I always assumed were cost and convenience reasons.
It's surely not a new battery chemistry. Lithium cells have a voltage in the 3-3.5V range. If you want more, you put them in series. And fed with an appropriately regulated supply, all common cell types will charge to full capacity from empty in 4 hours or so, reaching 50% sometime inside of 1 hour (that is, most of the time spent is in "topping off" the thing, broadly you can get energy into a battery at least as fast as you can get it out). It's literally no different than your phone battery.
If you’re buying a fleet of new aircraft I suppose it’s competitive but for similar price a Pilatus PC-12 gets you significantly more utility. Land just about anywhere and easily find fuel.
Another factor is these MSRP estimates are really hard to pin down before the aircraft is fully developed. In the early 2000s there was a flood of companies claiming $1 million jets. Eclipse Jet being the most notable. Most of those programs either didn’t survive or ended up charging more like $5-10 million. Getting an aircraft certified isn’t cheap and it’s really hard to get economies of scale on something so expensive.
I don’t want to completely discount the program but I keep going back to the charging when I try to flesh this idea out. The only possible way I see this succeeding is if the company also facilitates building a charging network. When I was in high school I worked at a small Midwest airport and the idea that the city, who owned the airport, would build charging infrastructure for a niche aircraft is laughable. They almost shutdown their Jet A fueling infrastructure (that they charged money for) because they claimed it was too expensive to maintain.
Overall point is that it’s doable but there are hurdles and a half baked idea and marketing fluff is going to result in yet another failed aviation venture.
Could they burn jet fuel in an electric generator? Maybe not economically, but the infrastructure is there.
I understand there are diesel aircraft engines that run on it - presumably this means that the injectors are different from all the engines I'm familiar with. You could install this engine connected to a generator and get a hybrid, though I don't know if it is a good idea. One the plus side you can put the engine where you want it for weight distribution reasons, because it is a hybrid you can always run at optimal rpm, diesel fuel has a better energy/mass ratio, and when/if it fails you have plenty battery backup so your wouldn't need as much maintenance as most aircraft engines get. On the negative side, you are paying to haul this engine around even on short flights.
> aims to have one flying early next year.
Using the present tense is not justified.
> The company plans to fly a prototype of the “Alice” design at the Paris Air Show in June ...
So yea, seems premature, since they're getting close to a prototype.
The character in my new novel Tina Taggins will be a gnome though. I haven't written in that character yet.
"is" vs "will" is a tense thing. This isn't yet a plane like Tina Taggins isn't yet a character in my novel so "will" is a appropriate.
For reference, typical business jets or twin props burn hundreds of gallons of fuel on a single trip costing hundreds of dollars. They also need frequent maintenance as there are a lot of things that need to be checked and fixed with such planes. So, the proposition of charging with cheap electricity and getting rid of most of the stuff that needs fixing and maintaining on a regular basis is highly attractive. If it works as advertised, this plane will sell like crazy. Electrical engines basically last a very long time and are easy to check and service. Charging batteries is comparatively cheap to burning fuel and likely to get cheaper in the future.
Practically speaking, if you have a home base with charging infrastructure but most other airports do not (yet), effectively you are looking at a 300M range for a return trip unless you are flying to a place with infrastructure to charge. That's still fairly nice.
For commercial operations, there are plenty of use-cases that would be well served by a plane like this. A plane like this gets passenger cost down to something that is quite competitive with a train ticket.
It is fascinating to compare with an electric aircraft. It's not so clear to me what the economics would be like as a whole.
It's not just fuel but investment and maintenance cost.
To me it might make sense in a short high frequency operation. Like to some island. Not as a business jet that mostly just sits around.
With electrical planes you'd expect similar benefits. Maybe a regular quick inspection of the few moving parts for wear and tear, make sure battery performance is fine and that any sensor read outs don't hint at any problems with cooling, performance, etc. Of course you still need to inspect the rest of the plane as usual. However, the engine tends to be one of the more expensive parts normally.
Jets are indeed reliable but they do need to be inspected regularly to ensure they stay that way. If e.g. there's some hairline cracks or corrosion, the engine might still work but be about to fail in some spectacular way. Inspections for that are expensive and a regular thing. Same with piston engines. Typically engines are certified for a fixed number of hours before they need their overhaul. I expect similar inspections and overhauls to be needed for electrical engines for the same reasons. But they should be much cheaper to do and the engines could likely be certified for much longer because there is less that can go wrong with them. So, less frequent inspections and overhauls, and cheaper inspections are a good thing. Also replacing parts / engines is likely to be a lot simpler if there are any problems.
Other factors are that unused engines tend to need more attention when you take them back into use. E.g. oil can solidify, fuel lines can clog up, etc. Most planes need to be flow regularly in order to avoid extra maintenance cost. To make sure things are functioning, you also have elaborate warmup and runup procedures before take off. A jet or piston engine is not usable until a few minutes after startup when everything is nicely warmed up and properly lubricated. Then you need to typically still go through elaborate runup procedures. Electrical engines are a lot less needy. Also they don't need to warm up, you just flip a switch and they are ready to go.
And that's aside from the fuel cost of course, which is a big deal as well.
What about the landing gear? Brakes? Control surfaces? All double size.
The battery will likely be a somewhat complex system with active cooling and monitoring and will need maintenance. They are aiming for higher than car level energy to weight ratios.
If they use a battery with air as a component, that's also again somewhat more complicated.
There's probably a trade off point in flight hours per year, above which the electric plane is more affordable. Depends on finances, too since likely it's more expensive to acquire.
Wonder how they made it light enough to be able to fly...
You get a massive weight savings in the engines and all related components. DC motors are multiple times smaller and lighter than the equivalent powered turbine engine when you consider the entire system. On top of that you totally eliminate the need for variable pitch props and the related transmission parts since electric motors can adjust power instantly. You also negate a lot of hydraulic systems (and their redundant backups) without the need for things like fuel pumps, thrust reversers, etc.
It also seems they are not using anything like standard li-po tech. From their site:
>Utilizing industry-leading lithium-ion batteries and a proprietary Aluminum-Air system for range, we’ve surpassed the 400Wh/kg mark.
For reference this is nearly double Tesla's energy density. Of course the cells will be much more expensive, but that matters a lot less for a low volume, high usage application that can be amortized.
Airplanes this size can use cruise missile engines, which are very light. See the F-5 for more info (7:1 thrust to weight ratio.)
> On top of that you totally eliminate the need for variable pitch props
Why is that? Variable pitch props have nothing to do with engine type. They're variable to be more efficient depending on RPM and speed.
> You also negate a lot of hydraulic systems (and their redundant backups) without the need for things like fuel pumps, thrust reversers,
Not really. A lot of flight controls are boosted with hydraulics, and thrust reversers are for increasing drag (descending faster or slowing down.) None of these depend on engine type.
The real issue with electric planes is that they're a fire hazard. Already people have been killed when their electric plane's battery caught fire mid-air:
The JAL 787 battery fire was a near-tragedy and resulted in interruption of service to SJC for 2 months:
I find the most erroneous posts on HN to be about airplanes and databases.
Variable pitch props have everything to do with engine type. They exist because turbine and piston engines have a very specific power/torque curve which requires them to operate at certain RPMs for certain conditions to achieve peak efficiency. With electric motors you have no need for this because you get a constant increase of efficiency across the entire power curve.
>Not really. A lot of flight controls are boosted with hydraulics, and thrust reversers are for increasing drag (descending faster or slowing down.) None of these depend on engine type.
Thrust reversers have nothing to do with descending faster or slowing down in flight, they are used solely for landing retardation. But an electric aircraft wouldn't even need thrust reversers. You literally just reverse the propeller immediately at full power when touching down. You can even save on less flaps required because the motors will be able to "windmill" on the descent and slow the aircraft as well as regen power.
There's also the engine-out design case, it's much easier to add prop feathering than add more power to the operating engines.
This design doesn't make a lot of sense, the props are located at literally the maximum arm from centerline, which requires bigger control surfaces for engine-out design (heavier and more drag) and gives very little ground clearance in crosswind landings. On the economics side, fuel costs are a small part of operating light turboprops/jets. The biggest costs are airplane depreciation/capital and crew. The real breakthrough would be an autonomous turbine plane that could eliminate crew cost and achieve 2000 hours/year utilization (versus ~200 for some privately-owned jets).
Tesla has shown battery tech is a safe and reliable energy source. However, this doesn't mean there can be no problem - of course there can! Airplanes also have had many problems with catching on fire, crashing, burning in the air.
That seem to be non trivial amount of weight.
I am curious how that compare to weight of typical fuel + engine for a small plane.
Slight quibble: that's specific energy (ie, per mass). Density is per volume. (For airplanes, specific energy is the hugely important metric)
The airplane can probably pack battery cells much denser than Tesla. Tesla uses active, liquid-based cooling; an airplane could employ the airstream for that. Plus I expect a lot less of battery heating; while the capacity is 9x of Model 3, the engine power (thus electrical drain) is around just 3x of Model 3. 
Also the metal shield under the battery can probably be done away with.
As others pointed out, electric engines are much different beast than any hydrocarbon burning ones. You need less support structure (for starters, less vibrations) and also much less auxiliary gear; think of all the cooling systems (either liquid cooling or flaps & openings & shrouds to direct air around); fuel tankage, pipes, valves, pumps & booster pumps; electric generator & possibly hydraulic pumps, and lots and lots of wires to both send electricity and control signals. As electric engines are essentially low-maintenance, you'd save a bunch of weight on monitoring instrumentation & servicing access panels. Maybe i'm reading too much into the renders, but the engine- and prop cowls seem to be very tight fit; both lessening drag and also simply being smaller, lighter parts.
Lastly, electric engines can typically be over-loaded way over their continuous power for well understood short stretches of time, facilitating extra power for prompt & safe take-off. Not so with piston or jet engines; the take-off power is typically maybe a dozen percent more than the rated continuous power, and that's about it. You end up carrying through the whole flight engines over-sized (and thus over-weight) just for the sake of take-off power.
Small weights savings all over the airframe add up.
 https://en.wikipedia.org/wiki/Tesla_Model_3#Specifications - 258 kW for Model 3 AWD, vs 3x260kW for the airplane.
They list a MTOW of 6350 kg. Less 800kg for 10 fully clothed adults and the weight of the battery, there's only 1000kg left for the plane. Maybe that's possible?
The thing is about 60% battery by take-off weight.
That's not as crazy as it sounds. A 777 is about half fuel at max fuel load.
Materials have improved significantly in the last few decades. There's a lot more possible now than in the past.
I'm sure they can make a battery lighter than a Model 3 battery (optimized for weight rather than cost), but how much lighter???
Unlike liquid fueled aircraft, you won't be able to trade off fuel weight for passenger weight to stay under MTOW.
Some back of the envelope math for the Model 3 battery: it has 4416 2170 cells, 66g each, is 291.5 kg, and the total battery pack weight is 478 kg. So only 60% of the battery pack weight is the actual battery cells.
Given how similar it sounds to that of a Tesla Model S + SpaceX - Battery, Electric motor, propeller and such, Why wouldn't Tesla attempt such a thing based on components they already build for Tesla or SpaceX?
VTOL will get less back because it's grossly inefficient.
Note that drag needs to be deducted from the potential energy. There's parasitic and induced drag.
Given that the aeroplane ends up stopped on the tarmac at (approximately) sea level with (approximately) empty tanks, how so? A bit of heat I suppose but that's not usable. I'd say current aeroplanes generally deliberately dump energy to the environment (via deliberately increased drag, spoilers etc.) during descent, no?
I think that compared to energy expenditure X in level flight at cruising altitude, the aircraft would expend X+Y in the climb and a little less than X-Y in the descent, assuming all horizontal distances are the same.
To the extent that they deliberately increase drag, that wouldn't hold true, but I'm guessing that's mostly on final approach.
Really? So, it's built and demonstrated?
> the first planes are being built right now.
Oh, so when you say “Eviation’s Alice is an all-electric, nine-person aircraft” you mean “Eviation claims Alice will be an all-electric, nine-person aircraft” and when you say “this isn’t another claim by another overoptimistic purveyor of electric dreams” you mean “this probably is another claim by another overoptimistic purveyor of electric dreams.”
Wow! One of the amazing things about EVs is how easy it makes it to reason about the energy usage. That’s about $250 in energy here in CA. I might produce a mW of energy with my solar panels on a good month here.
If it actually has a range of 650 miles then that comes out to be about 50c a mile, which would be quite amazing.
Remember airplanes have a fair amount of glide ability even with no engines. The airplane is coming down, but the pilot has a significant choice as to where and plenty of time to choose between alternatives and get there.
Also, the adverse yaw if you lose one of the wingtip motors or propellers will be severe.
But I don't see asymmetrical thrust as being a real problem on this plane. It has far fewer moving parts than the single- or dual- motor props that it aims to replace. This is not an ETOPS aircraft, and even if an outboard motor fails you still have that central pusher to help. Back to those razor-sharp wings: they are quite long and it looks like this plane would have a mighty fine glide ratio.