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Cora – Kitty Hawk's prototype air taxi [video] (youtube.com)
432 points by partingshots 4 months ago | hide | past | web | favorite | 273 comments

Another discussion on KittyHawk here:


Contrary to almost every comment here so far, this is both innovative and energy efficient.

Let's talk energy efficiency first. Once it's up in the air, it's has a similar profile to a normal single engine airplane. A Cirrus SR22 can go 1,200 miles on 80 gallons of gas. That's roughly speaking 15 miles per gallon - better than many pickup trucks or large SUVs. And that's while going 180 mph. Slower is more fuel efficient.

This aircraft is definitely going to make noise on takeoff and landing, but it's not going to make much noise while cruising.

The Dodecacopter/regular aircraft hybrid solves a lot of problems. Once it is in cruise mode, it is as safe as a regular small aircraft. Importantly, unlike a quadcopter, it does not crash immediately on loss of engine power - it can glide to a landing somewhere, or use a parachute, or land with its Dodecacopter rotors.

Unlike a rotor craft, this aircraft is very energy efficient while cruising.

The Dodecacopter side lets it take off and land in even more places than a helicopter. It looks like it has redundancy for any two rotors/motors to go out. If this happens on takeoff, you fly to an airport to land. If this happens on landing, you leave the aircraft on the ground until someone comes and fixes you. You skip all the transmission and cyclic complexity of a helicopter. This is going to cost a whole lot less to maintain than a helicopter.

In short, this has potential to be way better than either a helicopter or a small airplane. Even ignoring the air-taxi business, there's a market for this aircraft.

So let's flip to the business side. An easy target for making these at scale would be $500,000 per aircraft. (Might be able to half that, but lets be conservative). Operating costs at scale, max $100/hr, could be one quarter that.

On the revenue side, this would replace a two hour trip across a city in traffic with a fifteen minute flight. Unless you've flow small aircraft before it's hard to appreciate just how much faster it is not to use roads. There's definitely going to be some market for this - that's worth money.

> A Cirrus SR22 can go 1,200 miles on 80 gallons of gas. That's roughly speaking 15 miles per gallon - better than many pickup trucks or large SUVs.

Sure, let's take the most energy efficient aircraft and compare it to the least energy efficient passenger vehicles??? I mean, how can one even pretend that is a fair comparison.

More generally for energy efficiency, it is well known that the most efficient trip is a shorter one or one never taken. Many fans of these technologies are people who dream of living 90 miles away and fly into town in half an hour. Or as you described "this would replace a two hour trip across a city in traffic with a fifteen minute flight". Comparing MPG when your technology is designed to encourage more miles is a flawed approach.

We do seem to have different value systems. I believe applying energy to make human lives better is a great thing! Electricity usage in the western world is getting greener fast. Total usage is going down, not up. This isn't going to reverse either of those trends.

There's a popular perception that all aircraft burn energy like an oil refinery on fire. The reality is that small piston aircraft are approximately as fuel efficient as the vehicles around you on the highway (at least where I live) while getting you there a whole lot faster.

A Cirrus is a good comparison stand in for the KittyHawk aircraft because it has a similar design and construction style (ignoring the dodeca-props), four seats, and is the most common general aviation aircraft not designed in the 1950's. A Cirrus isn't even close to the most energy efficient aircraft - that would be more like 60 mpg, nor is it the most efficient in its class.

> The reality is that small piston aircraft are approximately as fuel efficient as the vehicles around you on the highway

This is just objectively wrong.

Before taking wind into account, a Cessna 172 travels 120kts on a good day and at altitude and appropriately leaned can get down to 8 gallons an hour.

120 nautical miles in 140 miles (less, but benefit of the doubt and all). That's 17.5 miles per gallon. At cruise altitude. Leaned appropriately. You can tack on another few gallons for the climb, and you're going mixture rich on descent so you're back up to 10-11 gph for the last 20-30 miles of your trip. You're lucky to get 10mpg overall for a flight, and that's using gas that costs $5 a gallon.

There are a LOT of benefits to GA flight in order to get around. Fuel efficiency is definitely not one of them.

He specified "general aviation aircraft not designed in the 1950's." The Cessna 172 was first flown in 1955: https://en.wikipedia.org/wiki/Cessna_172

Also, it may be worth taking into account that airplanes travel in straighter lines.

Planes are updated, just an FYI. And most GA aircraft are older. That's how most people fly, by buying an aircraft that is the price of a car (<$50k).

I fly a Cherokee 140. One of the most common aircraft, as with the Skyhawk. My fuel consumption is 8.4gal/hr at 75% mixture and 5.6gal/hr at 50%. Assuming I'm doing an average ground track of 100mph (for easy math), that's 12-18mpg (not counting that I'm 100% rich at TO and LND).

I wouldn't exactly call it fuel efficient, but it isn't burning like an oil refinery on fire either. I also don't pay $5 for gas ($4.09 today, but it isn't uncommon to see it at $3.50). But you do have to consider speed and time to destination if we're going to compare to cars.

One thing to also consider is that avgas is still leaded. And for anyone interested, here is the POH for the Skyhawk[1] and Cherokee[2]. Note that fuel consumption will be in hours or gal/hr when discussing aircraft. Mpg doesn't make as much sense.

[1] https://www.flyingd.net/documents/N739EF_172N_POH_000.pdf

[2] http://wilgroveairport.net/files/Cherokee%20140%20POH.pdf

Disclaimer: Use the POH provided with your aircraft.

But the whole point of this discussion is to evaluate the likely performance of a new aircraft, not the overall performance of the existing fleet. This particular new aircraft is electric, so leaded avgas won't be an issue.

Cherokee 180/181 checking in! $4.09 would be great, $5.12 at my base this morning. $0.35 club discount helps though.

I fly in the south and as long as I'm not at a major airport (in class G) I can get gas pretty cheap. Poking around on some maps I can even find it cheaper.

Really all depends where you fly.

I'm talking about overall miles traveled so I'm not sure the straight line thing matters. Yes for the same trip you will travel a shorter distance in a plane. The plane will also be running for 20-30 minutes prior to takeoff and 5-10 minutes after landing.

If you exclude GA aircraft not designed in the mid-20th century, you exclude 90% of GA aircraft and 99% of certified GA aircraft. We can make that distinction if you want but it ignores reality.

>The plane will also be running for 20-30 minutes prior to takeoff and 5-10 minutes after landing.

That's been true up until now, but this vehicle doesn't need to do that.

Also, most e-planes have a small motor in the wheel for taxiing.

>I'm talking about overall miles traveled so I'm not sure the straight line thing matters. Yes for the same trip you will travel a shorter distance in a plane.

I think you just answered your own question.

I think it's an important distinction in the context of evaluating the likely performance of a brand new aircraft.

Well for the autos you need to consider that they may commonly be in rush hour traffic, too, stopped and idling quite a bit.

It's a good thing the EPA has highway fuel economy ratings then so we can compare apples to apples.

> Electricity usage in the western world is getting greener fast.

81% of energy produced in NZ is renewable. Complex terrain would make such vehicle a saviour. Plus, in any terrain planes almost always travel less, so savings are intrinsic.

Finally, using "taxi" name here is awful. At the most it's going to be an entertainment device initially (tourism and extremely expensive attractions are insane in NZ), method of access remote places later.

> We do seem to have different value systems. I believe applying energy to make human lives better is a great thing!

Your conclusion that we must have different value systems only shows where you stopped thinking.

We differ in the timescale on which we consider the betterment of human lives.

And we differ in the subset of human lives we consider the betterment of.

If you remain convinced we have different value systems, then it's not about energy or the betterment of human lives (or straw lives), but about placing a low value on short-sightedness and egotism.

I think lowering the time cost of coming into the office would lead to more telecommuting than less. Since you can get into the office in 15 minutes, you don't have to go to the office every day just in case you need to have an impromptu meeting.

You're absolutely right. We should be encouraging density to save energy and be ecologically friendly. What's most wonderful is that we don't even need any new technologies to do it!

It may be possible that this is something of a politically difficult problem in many areas, though. Until San Francisco actually allows itself to become a real city, we may be stuck looking at workarounds. It's very, very, very far from ideal. Exactly as you say. But it may be the best we can do for now.

Solar electricity will be nearly free shortly, so efficiency isn't an important issue. Cost still is of course.

Solar is becoming so cheap that an excessive amount of generation will be installed, so adequate generation will be available in morning or evening, or with clouds. During peak sun, excess power will be basically free, so any battery can be charged during these periods at little cost. Wait and see if skeptical.

The most efficient trip is the one not taken but what do we lose by not taking it? Is that cross town trip trivial, necessary, or serve a higher purpose?

I don't think anyone would stop a human-rights march because of energy efficiency concerns. And who cares about energy efficiency when the energy is clean? It's well-known that the US is trending greener and this electric taxi is years away from widespread adoption.

Agree with most of what you say, but two open questions- debt alone on $500k amounts to $180/day (10yr am, 6%). Then there’s cost of energy, dead time during recharge, dead leg trips to the next customer, dead let to charge port, maintenance will be rigorous even if the plane doesn’t need it because FAA. Landing fees while be high for urban landing points, plus ground crew at some locations. “Max $100/hr” is way low, even Uber sits around that level for a $30k vehicle with 2x the efficiency.

Second- I have a hard one understanding how this could approach the aerodynamics of a Cirrus. All those fans will be drag monsters.

And a little side fun note on rooftop landing pads- ideally, a high rise has expose cooling towers on the roof, taking up most available space. Any rooftop landing facility would have to be constructed over that, at phenomenal cost per foot. Developers expect to get repaid handsomely for that kind of capex. If you aren’t landing rooftop, you are landing at an alternate location X blocks away, which could be a real drag of the other kind..

There is DEFINITELY a market for this plane, and it’s bigger than current heli, but it’s probably not ubiquitous air taxi service

I'd love a link to that Uber cost number - I'm having a hard time wrapping my head around a car costing more than $100/hr to operate. Even a New York City cab, rented to a driver from a profit making cab company and including the cost of the medallion was $120 for twelve hours of driving.

A chunk of a GA aircraft's operational cost is annual maintenance. By flying more per year, the operational cost of an aircraft goes down. I think you can get the operational of a Cirrus down to $100/hr if you fly it 500 hours per year.

However, operating this aircraft at scale would seem to have some real maintenance advantages beyond what you would typically see for General Aviation:

- There's only one moving part in an electric motor, vs all the complexity of a [edit: 6 cylinder] piston aircraft engine.

- You can specialize your people, procedures, and facility around a single aircraft type.

- You can swap out engines and avionics and work on them while the aircraft returns to flying.

And yes, this won't be as aerodynamic as a Cirrus, but it should be similar to a GA single engine aircraft, rather than either a quadcopter or a helicopter.

GA aircraft engines are rarely V6 they are mostly flat 6 or flat 4 for smaller planes. If you go to the website for Lycoming as an example you see they are all flat except for one I4. https://www.lycoming.com/engines

Thanks for thoughtful response!

- I was just looking at the cost for me to take Uber across town. My experience has a lot of 30 minute trips in different cities, which has equated to $50 rides on UberX, and that is always between urban centers and airports (i.e. ideal connecting points). My assumption would be that Uber gets as close to operating cost as feasible, if not cheating on the backs of the drivers, plus Uber hasn't actually made money (but thats a different discussion!). So thats my $100/hr for an Uber. Never mind the fact that personal car ownership is far cheaper.

- With very limited experience with general aviation, I have chartered a few private flights- for around $4000 for a day trip on a late model KingAir. Not worth much for this comparison. But thats why I looked to Uber as the absolute low end, because the best economics of air travel will probably only approach the best economics of surface travel.

- I just don't know why Cora's aerodynamics wouldn't look a heck of a lot like a quadcopter. My background is Civil engineering (im a static kind of guy!) so i dont know much here. All those extra surfaces add a lot of drag, no way around it. I wonder if they could turn the props and feather them up so they all align and provide lift with forward flight? I'm sure Eric Allison (engineering lead) is on top of it.

Dont get me wrong, I think its great stuff and I look forward to its development. However, there are a lot more problems to solve than just perfecting the actual aircraft. Its a whole ecosystem, not just an air shuttle. Recent history has given us a few great entrepreneurs who have overcome a multitude of problems in their space, but i definitely wouldn't bet too early on something like this without a little more to show for it. The New Zealand partnership will be a good prooving grounds.

EDIT: im happy to be wrong on all this!

Most GA aircraft don't cost 500k. Just want to put that out there. And I see Skyhawks and Cherokees go for $90-$150/hr.

I'm surprised almost nobody's talking about the relative change in safety yet.

Transportation accidents are the leading cause of "unintentional injury" deaths (i.e., not disease, suicide, or homicide) [1]. Although the absolute rates are somewhat low (7.28 fatalities per billion miles for cars and light trucks), you are approximately 100 times more likely to die while driving than flying (table 2 in [1]).

[1]: http://faculty.wcas.northwestern.edu/~ipsavage/436.pdf

This is not commercial aviation, this is general aviation (even if it's commercial in nature). GA is more dangerous than driving, roughly comparable to riding a motorcycle, and that's being optimistic.

Strong agreement - no sane company would operate a taxi company at the current General Aviation safety rates. They are going to have to do a whole, whole lot better.

Getting safer seems like it could be possible, but it's going to be an enormous amount of work.

There is no such thing as "commercial general aviation". Once you're accepting fee-for-service you are a commercial carrier with all the regulations that go along with that.

Just because you're getting a paycheck doesn't make your Skyhawk magically as safe as a 787. This is decidedly in the GA category in terms of safety.

No it doesn't.

But someone flying commercially, even in a Cessna is going to have quite a bit more training than Joe Pilot who flys 10 hours a year. A commercial and IFR certificate at the very least, and will also have to pass more stringent and more frequent medical exams.

These "driving related" injuries and deaths stats are almost always skewed because they include fatalities/injuries for drunk driving and night time driving. Someone only driving to work and back is at an absolutely minuscule risk of injury/death from driving.

I'm happy to accept ~pc86's correction up above, but I disagree with this rebuttal. The risk is minuscule in the absolute sense (several hundred fatalities per billion miles), and if you are driving drunk (or tired, or on painkillers, or while texting), your odds of collision certainly go up.

But just because you aren't doing those things, doesn't make you any less at risk from other people doing those things. You are still on the road, surrounded by, in some areas, hundreds or thousands of deadly machines operated by people who are generally almost capable of handling them.

I just finished an excellent book on this, "A Deadly Wandering", which examines distracted driving specifically but also touches on a few other related subjects. In the primary case that the book follows, and in the few others it mentions, distracted drivers walked away from wrecks where they had killed innocent other passengers or motorists.

Being in a car (or bike, or motorcycle) on the road is one of the most dangerous things the average person does on a regular basis.

Absolutely, I'm just saying that the risk you are in changes depending where you are and what you do, there is an average amount of risk but it doesn't apply to everyone.

I understand that some people have very dangerous commutes, but for some it's literally 10 miles of traffic moving at <10mph 99% of the time. If that's your "driving" then the risk of having a life destroying accident is almost nil and it's probably safer than walking or cycling at that point(you basically sit for an hour in a metal cage that's barely moving, surrounded by other barely moving metal cages).

Yes, there is still a chance someone else around you could be drunk or speeding or distracted, but if you are sitting in an 8-lane jam that's not really going to do much damage.

Not that it's statistically relevant, but my drive to work feels like my most dangerous drive, by far. An interstate that seems to have a fatal accident on it weekly, of which I'm usually within an affected time window.

Still not saying I'm narrowly avoiding death or anything, but man, the sheer volume of people going to work on the interstate every morning and night causes so many wrecks.

Great video on the Pan Am building rooftop helicopter service to NYC area airports.


The family flew on one of New York Airways' helicopters from Newark to Kennedy back in 1974. Pretty exciting stuff for a 4th grader!

This was an awesome video; I had no idea this type of thing ever existed. Thanks for sharing!

Blade, the company at the end of that video, had a fatal crash this week.

You can use battery swapouts instead of grounding the vehicle.

I imagine this same conversation when the car was first becoming a reality. You have to start somewhere.

Also the hovercraft - it's just that those turned out to be pretty niche.

Not to be overly nit-picky, you obviously know ASEL referencing the Cirrus but maybe I can add a little more of my own experience. I own a Cirrus SR20, and I'm lucky at cruise to get more than 12-14mpg running 8.5gph lean of peak at altitude. I just recently flew a NA SR22 up to Philadelphia from Tampa and averaged about 12mpg. You might hit those numbers you mentioned in a turbo at flight levels, but not low, and certainly without a tailwind.

The operating costs for my SR20 with all things taken into account: Oil, Hangar Costs, annual inspection and averaged annual repairs, engine overhaul allowance are close to being conservative $160/hr fuel included vs. about $70 about it being fuel alone. From my calculations, if I went with a NA SR22, I'd be closer to $200/hr for a non-turbo, and about $260 for a SR22T.

Keep in mind, those hourly costs don't take into account the capital costs, depreciation and other training expenses required to operate the vehicle.

It's hard to compare costs of a vehicle to an aircraft. To drive to the airport, pre-flight the plane.. file a flight plan and deal with being re-routed the terminal area trying to get into a busy airport often undermine the time savings of just driving, unless i'm flying out of the state. I don't fly because it's convenient or faster. I do it because the feeling of watching the earth drift away from you when the plane is leaving the runway never gets old. I love flying. :)

Thanks for some real numbers!

Wow there are all kinds of strained comparisons here as the other comment mentions.

One, comparing one of the most fuel efficient ASEL aircraft compared against one of the least fuel efficient passenger vehicle categories. Nobody uses pickup trucks for taxis. Nobody uses large SUVs unless you specifically request them (and they typically have a surcharge).

> Once it is in cruise mode, it is as safe as a regular small aircraft.

Well landing and taking off are the two most dangerous phases of flight. "Once you ignore the two most dangerous phases of operation, operation is as safe as you'd expect."

Not to mention that small aircraft/general aviation is not safe. Most life insurance excludes it. If you're under 140 hours TT and not instrument rated, life insurance that explicitly includes GA is prohibitively expensive (I received a quote at 80 TT and pre-IR for nearly $300/mo for a 10 year term on an otherwise healthy 30 year old male, comparable policies with a GA exclusion are $10-12/mo).

The most optimistic figures put GA roughly on par with riding a motorcycle without a helmet.

> An easy target for making these at scale would be $500,000 per aircraft.

Look up the cost of a new Diamond DA-20 or Robinson R44. There is no way you can build one of these things for less than $750k+ at cost so you're going to need to sell them at 1.5-2x that or more. And that's at scale.

And speaking of scale, what do you think the market for these things is? You're not going to be selling millions of them. Cessna sells a shitload of planes compared to the rest of the industry and they sell one factory new plane a week, almost exclusively to large institutional flight schools.

> Operating costs at scale, max $100/hr

I know "lol" is code for "I breathed through my nose a little louder," but this actually did make me laugh. Operating costs will be the 2-3 times this at scale. And 5x+ now.

I fly a single-engine plane with over 30,000 units in production (PA-28-181). They're everywhere. The lower HP version is a very popular trainer aircraft, and as such need to have low costs of ownership and maintenance, and high reliability. I fly this plane as part of a non-profit club and still pay $100/mo and $100/hr to fly a 45 year old plane with no autopilot, steam gauges and a carbureted engine.

I don't get how it is physically possible that this plane is energy efficient? The smaller prop, the less efficient the thrust conversion. You also need laminar air for rear props to be efficient. The drag on the wings should create a ridiculous wake behind the aircraft. I would love to learn how KittyHawk are trying to mitigate these problems (which are huge constraints even for major players).

>The smaller prop, the less efficient the thrust conversion.

Right, because the actuator disk loading[1] goes up, meaning that you're "throwing air downward" faster, with thrust scaling as v (momentum) while power scales as v^2 (kinetic energy). This is why propulsive efficiency decreases as exhaust velocity increases (for rockets this is simply exhaust velocity, while for air-breathing engines it's the change in velocity caused by the propeller/turbofan relative to the original airstream velocity).[2]

So bigger props are more efficient, because the actuator disk has more area. But the other way to add area is to add propellers. This has 12 props, so the disk loading is 1/12th as much.

The equation for hovering power is:

  P = (mg)^3/2 / sqrt(2 A ρ)
So twelve rotors only needs 1/sqrt(12) = 29% as much power for the same thrust as a single rotor of that size. Or equivalently, having 12 rotors is like having a single rotor that's 3.5x as large in diameter.

>You also need laminar air for rear props to be efficient. The drag on the wings should create a ridiculous wake behind the aircraft. I would love to learn how KittyHawk are trying to mitigate these problems (which are huge constraints even for major players).

They showed CFD in the video, so apparently that combined with test flights and scale model flights (both shown on their website).

Notice that the propellers are rotated slightly inward, but the outer propeller (that rotates in the opposite direction) is angled outward. I suspect they're managing the vorticity of the propeller wakes, using it to lower induced drag (effectively creating a longer "virtual wing").

Also, it looks like they transition to horizontal flight and then shut down the rotors (or at least, dramatically lower the power). The video shows the hovering system shutting down and self-aligning the propeller blades into the airstream.

[1] https://en.wikipedia.org/wiki/Disk_loading, https://en.wikipedia.org/wiki/Actuator_disk

[2] https://en.wikipedia.org/wiki/Propulsive_efficiency

> I don't get how it is physically possible that this plane is energy efficient?

Energy efficiency is not all or none - it's a question of how efficient it is. Whichever way you dice it, the final result of the combination of energy density, thrust, weight lift, drag, is a plane is efficient enough to have a claimed range of 100km. If it were more efficient, it would have a longer range.

It is all relative on efficiency IMHO. And since it is electric which can be powered by "clean energy" how do you measure it.

Efficiency is not relative especially when it comes to mechanical movement. It is quantifiable data and nature does not care whether the energy is "green" or "clean". Energy is energy regardless how it is produced. Though the best data they can provide is the lift to drag ratio at cruise speed. This will give us a pretty good idea on how this aircraft performs.

Just be careful about how you quantify, the energy needed to overcome that drag ratio will presumably be delivered far more efficiently via electric moters, since they'll not be throwing 2/3rds of the energy away as heat.

So an electric plane could be twice as inefficient in other ways (e.g. extra weight for batteries) and still come out ahead overall. And that's before taking carbon and pollution into account.

> On the revenue side, this would replace a two hour trip across a city in traffic with a fifteen minute flight.

If a city takes two hours to cross in traffic, that's a clear sign it needs a subway or monorail.

Which both cost billions over billions, and you will not achieve that good connection for the majority of citizens with just one line.

They're expensive, but massively more efficient than other transport. Plus they reduce congestion for anyone who doesn't have easy access.

I could understand why say, Lagos wouldn't have effective mass transit. But it's hard to see why major developed-world cities can't justify the investment.

I think people misunderstand my GP comment. I am VERY pro subway and public transport in general, and I go by bike whenever I can. But there’s a tool for every job, and one subway line won’t solve the same problem a thousand air taxis are going to solve. They don’t even play in the same league. One connects city parts loosely together and relies on other last-mile means of transport (walking, taxi, park&ride, kiss&ride, bike,...); while the other is a whole-in-one, it’s more exclusive (use once per month vs twice per day) and way faster (minutes instead of hours).

Do we need more subways? Heck yes! I want one in my hometown. Do we want air taxis at the same time? Well, why not?

This aircraft can't take off and land any place that a helicopter can't. It's subject to the same laws of physics, and the same safety and noise regulations.

But it may find a niche market by being faster, cheaper, and easier to fly than existing light helicopters.

The noise regulations part does make a difference, as this is significantly quieter than a helicopter.

That remains to be heard. The electric motors might be marginally quieter than current helicopter engines but ultimately the rotors still have to move the same amount of air.

In addition to ameister14's point, OP was also pointing out that you can glide to land on little to no power, where as a helicopter can't do that.

Glide where? This aircraft seems to be targeted toward moving people relatively short distances around dense areas. If you're in a city, look around. How many suitable emergency landing sites do you see with a large, flat, open area without nearby buildings, overhead power lines, or trees? If it loses power at low altitude it's not going to be gliding very far no matter what.

And as others have pointed out, helicopters are perfectly capable of autorotating in case of power loss.

> emergency landing sites

Well, there's beaches near some coastal cities that afford survivable landings, but may be risky for others.

Last year there was a tragic case near Lisbon where two people on the ground died. It was a flight lesson with an experienced instructor, who followed protocol and landed on sand at the water's edge. (My understanding of the discussion at the time was that hitting water with fixed landing gear is an almost certain death sentence for the plane passengers, because it flips over instantly.)

Unfortunately, without power, the pilot missed a more deserted stretch and ended up in a section of the beach with quite a few people enjoying the summer at the seaside.

One of the reports in the Portuguese press: http://observador.pt/2017/08/02/avioneta-despenha-se-na-prai...

Any large street could probably work well?

A helicopter can survive a complete engine out at any point during appropriately chosen flight regimes: https://en.m.wikipedia.org/wiki/Helicopter_height%E2%80%93ve...

In my layman understanding: the heuristic amounts to - at low altitudes you flare and cushion, and at high altitudes you enter autorotation.

Helicopters have a mechanism called autorotation which ensures safe(albeit sharp) landing when the engine fails.

Helicopters can autorotate which isn’t as efficient as a glide but will still get one down safely.

The two words you need when making a justification is reliable and safe. It won't matter how innovative and energy efficient it is if it doesn't meet the above requirements. If the osprey taught as anything, flying unconventionally is hard.

I totally agree with you - getting this to beyond current single engine aircraft safety rates is going to be the challenge.

However, they've got a far better starting platform for doing this than anything else I've seen. It's made out of simple pieces with a lot of good options when things go wrong.

Maybe remove the rose-colored glasses?

1) 15 minutes? If you flew in a small aircraft regularly, you would know it takes 40-60 minutes to prep a plane from park to airborne in zero traffic.

2) Estimating what the fuel consumption of a small aircraft will be is much, much harder than a surface vehicle. Consider 90% private aviation disasters are a result of pilot error. And 90% of pilot error is in fuel consumption estimation.

     15 minutes? If you flew in a small aircraft regularly,
     you would know it takes 40-60 minutes to prep a plane
     from park to airborne in zero traffic
How much of that prep is eliminated by going full automation? Isn't most of the prep the pilot running through a checklist?

If there is unavoidable time consuming checking, you could do that in advance and provide the plane as an autonomous taxi. So it shows up, picks you up, drops you off.

> Isn't most of the prep the pilot running through a checklist

Yes, but...

Things like "check your propeller for cracks", or "verify that the control surfaces are actually moving when the controls say they should have moved" should not be skipped.

But you can skip a lot of things just by virtue of this being an electric vehicle - like "visually verify fuel level without using the gauge", or "check oil level", or "test carb heat" or "verify dual magnetos" etc.

If these are automated, though, they can be done in parallel. A camera pointed at the propellers can be checking them for cracks at the same time that another camera is checking that control surfaces actually move.

there are better ways to detect aileron deflection via automation than with a camera, but I take your point.

> 15 minutes? If you flew in a small aircraft regularly, you would know it takes 40-60 minutes to prep a plane from park to airborne in zero traffic.

It takes 10-15min (max!) to check a Cessna 152, start, and call for departure clearance. Add on another 10-15min for taxi via the pumps & power+pre-take-off checks, you still have 30min left to play with.

I do agree with your main point that you don't just hop in and turn the key, just think that an hour for all that is taking your sweet time.

That fifteen minutes is for flying time in air taxi service. So you get into an aircraft ready to fly. I'm guessing two minutes of liftoff/landing and transitional flight on either end, and 11 minutes/22 miles of cruise in between.

Running out of fuel seems like less of a safety concern with this. Since it can land vertically, there are way more sites where it can make an emergency landing if the range estimate turns out to have been too optimistic.

Also, with a computer flying, you can do something less extreme: actively and continuously manage the compromise between speed and efficiency. If your confidence of reaching your destination drops below the required threshold (say 99.999%), slow to whatever speed is required to achieve that confidence.

The performance of this aircraft is piss poor. Why compare it to as SR22? Let's try an R22.


  Range 240 miles
  Speed 110 mph
  Price $250k

  Range 60 miles (1/4 that of the R22, 1/20th of the SR22)
  Speed 93 mph (half that of the SR22)
  Price ???
This thing is a dog. Cool design, I think it has promise, but let's not pretend this is in any way more than a concept being shoehorned into a niche commercial application.

It would be happy if they had anybody of who has some semblance of an aircraft design engineer background.

Their first try: zee aero made a barely flyable contraption that was nuked by American FAA, and rightfully so.


This time, I don't see this being much better. My early childhood aspiration was aeronautics. I believe as somebody who built a semiflyable motoglider as a 15 years old in 2006, I can comment on technical soundness of this. Biggest red flag in the design are fans in front of the wing. Turbulence from them will be randomly stalling the wing, and most likely asymmetrically - which leads to a corkscrewing risk, especially with that huge elevator.

Imagine being able to live 90 miles from a town and commuting in 30 minutes regadless of peak hours.

As for the noise, if it can land vertically, I can immagine it making a steep descent on top of a tall building, unloading passengers and then autonomously taking off to pick somone else some other place.

Nope - NYC used to have a lot of air taxi traffic and after the horrendous accident on the helipad on the top of Pan Am building all air traffic was banned inside the city. Helipads are only allowed along the river. I imagine other cities would impose similar restrictions.

> I imagine other cities would impose similar restrictions.

Imagine what you will, reality still exists. Some places have similar restrictions, some don’t - there are helipads all over Los Angeles for example.

A safer, quieter ‘air taxi’ is more likely to reduce restrictions than add to them.

There will still be traffic if everyone is heading in to the same few spots. There's only so many spots these things will be able to land, not to mention they will need to maintain a certain amount of separation from other air traffic.

Yeah, now imagine tens of thousands people an hour being able to do that.

I hear they have trains that can do this in far away lands. Trains that go 180 mph. Not in my backyard.

Trains that go 180 mph have a way of draining your pocketbook. If you don't work near a station, or live near one (or, worse, both) you face commuting hassles. You may have to take a train that averages 30 mph as it makes all stops to get to the 180 mph express one.

It actually works well enough in japan: 15-20 minutes on a local to get to the Shinkansen station, then an hour on that, then another 15-20 minutes to get where you are going. Not really in daily commute range, but definitely viable weekly.

It won't be 30 minutes. It'd be a few hours. First because they said it could go faster than 150kph, which means it tops out at roughly 90 miles an hour. Second, the range of the thing is about 60 miles, so you'd have to charge it partway.

Swapping batteries is a no brainier for this tech. There is zero reason to have a 500k aircraft waiting around charging vs having 2+ set's of batteries.

Electric cars have a long enough range and are mostly single family so swapping is less useful.

Reserve is a much larger issue, aircraft want to keep ~1hour of reserve these things are starting with less than that.

I don't know how practical it is to build one like these yet, but really like the design of Lilium, and it has 2x the speed:


I was thinking something similar, and per the Bend Oregon article that was here before (https://news.ycombinator.com/item?id=16517929) it could make commuting work from further away, although with only 100 mile range that is a bit challenging. (Bend to SF is 500 miles)

I am also wondering about the ergonomics for people who are mobility challenged.

On the plus side, their launch material successfully has gotten me past thinking that they are building quad copters for people into thinking about what they might be used for. The numbers pencil out for relatively short commutes.

A lot of negative comments here. I must say I'm impressed and I applaud these people for building an innovative working thing and taking it to production. No pilot - mind blown.

And sure, this might not be the solution to humanity's overall mobility, but heck I can see it being useful in many ways.

Sadly negative comments are the norm here on hacker news. No matter how amazing the news, the top comment is usually a snarky takedown of the linked article.

(It's nice to see the top comment on this one is actually positive!)

I agree that the technology is exciting to see but I think there is a lot of negative comments because there is a lot skepticism (which engineers tend to be including myself due to the nature of our work). That being said, most commercial flights are actually on autopilot during cruise. Pilots can choose to use auto takeoff and landing as well but I believe it requires a specific license and copious amount of paperwork. Pilots are important because of liability and federal law.

>Pilots are important because of liability and federal law

Pilots are important because if the autopilot gets even one little thing wrong it cannot recover and people die. Autopilot is more like "Auto-level and navigate" It is not designed for emergency situations. What kind of license will this vehicle require?

As a pilot and engineer, I think there are good reasons to be skeptical. Here's some of my questions.

1) Can it autorotate? Or in an emergency does it have to glide?

1.5) What's its glide distance? Cruising altitude? There's a lot of drag from those propellers so I imagine its best glide speed isn't great.

2) How are you going to get it in a city? Seems like you're going to have to go to the local GA airport (which are fairly frequent, but you'll still need a normal taxi).

3) There is a really limited range (100km or 60mi) and only goes 150kph (90mph) (I'm guessing max cruising speed, so real world you'll see it going slower, plus you have to consider TO and LND). That's not very far and not very fast.

4) GA is dangerous. How is it communicating with ATC? Can ATC divert it? Will it integrate into the standards (N1234 fly one niner zero). What happens when someone doesn't use the standard (this WILL happen)? So can it fly in class B airspace? I even have questions about class C and D. And how is it going to handle GA aircraft? And if it is in class G how does it deal with that person that isn't using the radio? Does the computer know when its own radio isn't working? And does it know ATC light signals?

5) Who is doing the inspection? In GA we check everything before we fly. Sure you can automate fuel levels, oil, etc. But how are you checking things like propeller or airframe cracks? And is it doing runups? How often?

6) Is it VFR? IFR? What altitude is it flying at? How does it handle cross wind? Which is going to be a big pain if you are flying in cities.

And as to why pilots not only choose, but are required (in the US), to do TO and LND is because that's BY FAR the most dangerous part. I can even tell you I'm thinking a lot more during TO. As a pilot you're constantly thinking about what you're going to do if there is an engine failure. During TO you're under 1000ft and the runway is behind you (you can't turn around). LND, well at least you got the runway ahead of you. Cruising? You got plenty of time to figure out where you're going to go. Pilots aren't just required because liability and federal law, they are required because automation isn't there yet. I can tell you that it is hard to see aircraft in flight. Especially in conditions like sunrises and sunsets. Many accidents happen on clear and sunny days.

There's a lot of things I like about it, but there is legitimately a lot of reason for concern. But it is a prototype after all.

FAA struck down google's first prototype, that's why they test in NZ

That would really give me concern.

Can anyone chime in how this aircraft is so energy efficient? It seems like the props on the wing will give a ridiculous amount of drag. Also, one of the key requirements for an energy efficient rear prop plane is super laminar air going to through the rear prop for efficient thrust. The wing design seems to remove this advantage.

Edit: Also, I thought smaller props for vertical flight is significantly less efficient than one large prop like a helicopter?

That being said, I always had a soft spot for aircraft startup after working at one in my younger days. Pretty interesting to see how this ends up especially with Sebastian Thrun on the team.

It's not. It has a range of 60 miles and cruise speed of 93 mph, giving an endurance of 40 minutes. In fixed-wing forward flight, this aircraft is slower than an R22 designed in the 1970s, which can fly 240 miles at 110 mph. I have no doubt that they spent a lot of time optimizing the rotor/disk hubs on this thing for forward flight, but anyway you slice it, it's a very messy wing. That has compromised its performance in both forward and hovering flight, while gaining mechanical simplicity. What this is is a first step, and as battery tech improves, this is the right direction. But the performance is not impressive. This is like a self-driving electric golf cart you ride to get from your doorstep to the entrance of your gated community, in a world of Honda Civics that go 500 miles on a single tank.

I don't know for sure, but I think that autorotation of the multiple vertical rotors provide substantial lift even if they're not being actively driven, similar to the tree seeds that autorotate as they fall.

I wonder if the auto-rotation is enough to overcome the drag from the huge wake they produce. The wake has to be almost the size of the aircraft with the wings oriented as so.

If you look carefully during the video, you can see that while in forward flight the rotors are aligned and locked in a forward position, which presumably reduces drag a fair amount. But yes, I can still imagine them producing a lot of drag.

Auto rotation converts air speed (i.e. drag) into lift. That may slightly reduce the relative costs of drag (by providing benefit) but it still has to be overcome by forward momentum.

But that's probably more of an issue for max speed than it is for efficiency, which would explain why it's operating speed is only 150kmph.

From the video the rotors seem to park in fixed wing flight. The extra large hubs may be designed for lift generation, however.

From an aircraft design perspective, it is an interesting choice.

I can't help think that this design, with dedicated lift engines is just not very mass efficient. The pylons and the twelve motors also add a lot of drag in horizontal flight, even though they've taken steps to reduce it.

As of today, if I was designing an air taxi from scratch, I'd go with a tail-sitting VTOL, like the E-flite X-VERT:


For a full-sized aircraft, since you can't vary rotor speed very quickly for large motors, you'd need to add variable pitch propellers. The passengers would sit in a pod which rotates to keep them level during all flight modes.

And, as other commenters have mentioned, a ballisticly-deployed parachute for safety. And maybe emergency landing skids for a horizontal landing if needed.

I know that electric flight is part of the selling point of this design, but I'd still prefer to use fossil fuel for the energy density.

I'd love to try it out if it goes into production!

Small planes have had parachutes for quite some time [1] now and have saved many lives. Why on earth would this company put people up into the air unmanned without one? [Personally, if a parachute was onboard I wouldn't mind jumping into one.]


AFAIK it's basically just Cirrus that has a parachute system (CAPS in their case). Others don't, and there are plenty of other plane manufacturers with many, many planes in the air.

Cirrus were a pioneer in factory-fitting but other types, even microlights, are also fitted with recovery systems. Magnum is a common brand in Europe.

BRS who make the CAPS for Cirrus also provide retrofit kits for Cessna 172 and 182.

> [Personally, if a parachute was onboard I wouldn't mind jumping into one.]

The cabin opens in a clamshell fashion and that appears to be the only way in or out. Opening the canopy mid-flight would probably result in shearing it off once it catches even a small amount of air. From there, you're left with exit point that's ahead of the wing, ahead of the main propeller, and ahead of the rather wide tail section.

Maybe you'd be clear if you hugged the bottom of the door and kind of… rolled underneath at exit?

As a skydiver who's exited all sorts of planes in all sorts of ways, I would rather take my chances landing with that plane.


Edit: on further review, I believe you mean "if the aircraft were equipped with CAPS, I wouldn't mind flying in one" as opposed to "if the aircraft came with a bail-out rig, I wouldn't mind strapping it on". Nevermind :-)

The Cirrus has a whole aircraft parachute - you can see it used here: https://www.youtube.com/watch?v=J94sGh8fQN8

Oops, I mis-read the comment. Edited to clarify.

Maybe if you had the thing switch to hover mode and then jumped off of the front?

I agree that jumping out while it is moving is suicidal.

The CAPS system makes the most sense, especially given the intended market of "person with cell phone and lots of cash to burn". They would be seriously limiting their clients if they required everyone to be jump certified.

As a skydiver, and expecting to see this thing in the small airports where I jumped, I wonder if the autopilot has been trained to avoid open parachutes.

Yeah. Check out the video I linked. No one is taking about jumping out of planes.

As mentioned in another HN thread, the Cirrus system is certainly spectacular, but it is heavy, requires a $15k repack every 10 years, and doesn't prevent a large fraction of accident types (e.g., an uncontrolled spin). They are most necessary for private (human) pilots who are the most dangerous kind. It's plausible that the increased safety from an autonomous system will make parachute systems unnecessary, but you'd have to dig into the statistics.

That's still very much a premium feature and not at all commonplace, based on my friends with PPL and the trade shows I've been to.

They claim that it is quiet, but there is no audio to give any sense of that. I would want to hear two people having a conversation while it takes off nearby.

Zero chance this thing is anything a normal person would consider quiet. Moving enough air to generate the thrust it takes to transport humans is not quiet.

Even from the video, it doesn't sound too quiet to me, and I'm sure they tried to minimize how it sounds in the recording, or at least they seem to be cutting off the video quickly when there's some noise in the video.

It may be 2-3x quieter than a helicopter, which I'm sure the engineers from the project would consider it a big innovation on its own, but that's not exactly what I would consider "quiet".

But as I said in the other thread, I think this is a fine technology to have in the future, and I'm not too critical of it, like I would be if this was a hydrogen-powered air taxi for instance.

It's battery powered, it's "self-flying", and the noise should improve in the long term, even though it will never be "quiet". I think there's little not too like about it. Range is not amazing, but for a first-gen fully battery-powered air taxi, it's not bad at all. They'll probably reach 5x as much by 2030.

For those who are not aware, the kittyhawk is the place where wright brothers tested and developed their plane.

Kitty Hawk, NC - to be specific! It's why North Carolina license plates say "First in Flight."

I'm very skeptical on the energy expenditure here, this does seem to be a fairly energy intensive mode of transport, but I assume the market would balance the price accordingly.

It certainly doesn't seem like the sort of thing that would become a mainstream mode of transport without a big change in the energy market.

According to the 2016 Uber Elevate study, traditional cars achieve about 1 mile/kWh, electric cars about 3 mile/kWh, and electric planes about 2 mile/kWh.

To simplify, one trades roll drag for induced (=lift generating) drag, at higher speeds.

The bigger issues are battery performance (specific energy), and regulation, in my view.

New Zealand does have an absolutely insane amount of wind farms. Even if it's not energy efficient, if it's low emissions in that particular market just by the means of energy, it could be useful.

That being said, energy there is insanely expensive due to asset sales; some of the highest cost in the world.

Energy efficiency doesn't matter when it's electric. We don't have to worry about burning up the sun because we used it up too fast.

I had to check it's not April 1st. Especially after watching the youtube video. I'm still skeptical that it won't turn out to be an april fools prank.

I'm developing a paranoia that the Alphabet moonshot projects are just PR to obfuscate the data privacy issues of Google's advertising.

I think it's perfect for transportation. A share model could really exist with it, less infrastructure.

If it becomes popular, entire cities could change how they look ( roof = taxi, roads for bicycles and deliveries on the roof)

This will be great for millionaire 1% Googlers to fly to work from Monterey.

I don't like that they're touting no emissions. Electricity has to be generated and in the US that's mainly coal. Hybrid vehicles are closer to having it right where running the car charges it and you can get by burning significantly less fuel. Strictly electrical has not been shown to be an energy saver or a flag bearer of emissions reduction. In many cases so far it has been a cause of more pollution than modern engines using oil.

> Electricity has to be generated and in the US that's mainly coal.

Huh? Coal is only 30% of the USA’s energy production, natural gas is higher at 34%.


The other points in your post are equally dubious, do you have sources?

Are you suggesting natural gas generation is “Green”?

No, I’m only suggesting that natural gas isn’t coal.

From an air quality perspective, at least, natural gas is much better than coal. But it is far from carbon neutral.

Wikipedia lists energy consumption being 70% coal, I'm not sure why the large discrepancy there. I got my information about electrical engines from a website trying to talk up how great it was that we were moving away from oil based engines, but even there they admitted that until more power generation is switched over to renewable that emissions are higher with electric cars. Which makes perfect sense and is not dubious, the fewer times you need to convert energy the less energy wasted. Electricity does not store well, additionally.

> Wikipedia lists energy consumption being 70% coal, I'm not sure why the large discrepancy there.



Yeah that'd be the link it's the first image on the page.

The image/graph you're referencing illustrates "United States total primary energy consumption by fuel in 2015". Total, not electric.

You were discussing production of electricity, which is shown in the table I linked on that page to be 32%.

Wait, how does that make sense?

What kind of energy if not electrical is coal being used to produce?

I think the Wikipedia image (at the top of the page [1]) is simply wrong. If you follow the link to the source, [2, page 43], you get 396.3/2280.6 = 17.4% for coal in the US, "Primary energy: Consumption by fuel."

[1] 1https://en.wikipedia.org/wiki/Energy_in_the_United_States

[2] https://www.bp.com/content/dam/bp/pdf/energy-economics/stati...

I looked at the citation, someone put the wrong numbers in the pie chart: https://en.wikipedia.org/w/index.php?title=Energy_in_the_Uni...

Blast furnaces, heating, other chemical processes.

Coal isn't used for heating much in the US, if at all. It is sometimes used for metal production, especially on the east coast, but oddly, not on the west, where hydro is used.

An airplane powered by fuel cannot be zero emissions. If you don't make any changes to a 737, it will continue to emit the same amount of CO2 etc. until the end of time, regardless of what happens in the rest of the energy sector.

This vehicle can be zero emissions today, if the power required is generated by wind/solar/hydro/etc. Sure, with today's grid's it won't necessarily be ZE, but it can be, and as time progresses and grids get updated with more and more renewable energy, it's effective emissions will continue to go down, with no changes needing to be made to the vehicle itself.

That's important.

Fortunately, the US isn't the only country on the planet. We could, for instance, get inspiration from those countries that heavily invest in renewable energy.

Most countries are not much better sadly, see https://www.electricitymap.org/?page=map&solar=false&remote=... for EU

Then you'll be happy to hear that they're trialling it in New Zealand first, which according to your map is at about 91% renewables for both islands.

Well, they are testing it in New Zealand, which this map shows to be doing extremely well in that regard.

You're talking like renewable energy isn't taking over everything.

Let's build everything together because if we assume electric cars will never work because energy sources suck right now, our planet is definitely going to be worse off.

Is there a good source for electric vehicles causing more pollution than modern engines? I haven't seen anything to that effect.

Here's an article that suggests that, in the US, gas cars would need better that 55mpg to have lower emmissions than EVs powered by the grid. In France, because of their different grid generation systems, you'd have to have a car running at 524mpg.


Look up the "long tailpipe" argument. I can never tell whether people using it are genuinely in favor of more effective tactics for reducing carbon emissions, or instead are just trolling EV fans.

From Wikipedia,

> Renewable electricity in New Zealand is primarily from hydropower. In 2015, 81% of the electricity generated in New Zealand came from renewable sources. In September 2007, former Prime Minister Helen Clark announced a national target of 90 percent renewable electricity by 2025, with wind energy to make up much of that increase.

They said this was starting in NZ, which is quite different than the US in terms of energy sources.

Yes, New Zealand had 40% renewable energy in 2016, which is 4th in the OECD in terms of energy share [0]. They are also an island, thus they have an incentive to generate their own energy and store it in battery-powered vehicles, rather than importing fossil fuels from afar.

[0]: http://www.mbie.govt.nz/info-services/sectors-industries/ene...

Coal is 30.1% of US electricity generation and dropping fast which is a long way from 1/2. We do use 31.7% natural gas, but that's still only adds up to 61.8%. On top of that the thermal efficiency is vastly better than cars.

My ears went up at that too, but it's very marketable and it is a good thing. Moving the emissions away from the end user and up the energy supply chain is a good thing. It simplifies the problem.

There are other countries besides US. They are testing in New Zealand which has a goal of zero emissions quite soon.

Also, if you think in 10-20-year perspective, US is on that way too.

What's the long pointy bit that sticks out from the nose for?

A single pitot probe it seems, so no triple redundancy? Also cannot spot any angle of attack sensors or anti icing measures (perhaps electric?). I hope it has a BRS at least..

There are a lot of things in aviation written it blood. A lot of work hours sunk into inspecting the swiss cheese from every angle, until the light does not shine through. Not the most welcoming ground for "disruption".

Still, even the most modern autopilot will drop the controls to the pilot's lap almost routinely.

>Still, even the most modern autopilot will drop the controls to the pilot's lap almost routinely.

And is likely why their "you won't need a license to ride, because it's automated" line is going to disappear once the FAA notices this.

It is for measuring what the air is doing (speed/angle) before that air is affected by the aircraft. It is something that's almost every test aircraft has. For example, https://en.wikipedia.org/wiki/List_of_X-planes#/media/File:G...

Once this data is gathered during the test program, the production aircraft can use less obvious sensors to measure what is going on.

air speed sensor, need to be out of all the air turbulence to be accurate

I love it. Can’t wait to see the first batch of production reviews from customers.

Also on energy usage:

Why does it matter how much electrical energy it uses? We know how to harness a near infinite amount.

> Why does it matter how much electrical energy it uses? We know how to harness a near infinite amount.

This is a silly thing to say while there's still quite so much CO2 being emitted from electricity production.

I suspect the OP means solar and wind. It’s a fair point given that these have batteries, and could easily swap them out for precharged ones.

Care to share this infinite energy idea?

You know very well which source he's talking about. And he said say near infinite, precisely to defend against obnoxious commenters.

Could you please name the technology? I work with renewable energy and I have no idea.

Are you talking about nuclear?

Ancestor comment is probably daydreaming about being in a Kardashev 2 civilization with a full Dyson Swarm collecting 100% of the Sun's total energy output, in all directions.

Some estimate we're currently only at Kardashev 0.8, harnessing about 80% of what energy from the Sun hits the Earth, while others argue that this percentage is much lower.

Ideas are easy, implementation is hard.

Edit for clarity.

>Some estimate we're currently only at Kardashev 0.8, harnessing about 80% of what energy from the Sun hits the Earth.

80% seems super high, unless by 'harnessing' you also mean things like 'the sun energy warms up the ocean allowing fish to live which we then consume for some% of the energy that sun sent'.

I'd be pretty surprised if efficiently used energy / energy hitting the earth from the sun was >20%.

We aren't in the same universe as 80% of the Sun's energy that hits Earth being used.

The numbers I'm seeing are 174 petawatts hits Earth and the world uses 18 terawatts of energy.

I still don't know, I'm sorry.

Because it claims to be green, and you'd need a green way to harness that amount on demand.

Are you aware of how inefficient our current solar panels are?

My understanding is that a larger, slower turning propeller is more efficient than a smaller, faster propeller. If so, why do drone companies/small aircraft companies have been pushing the more and smaller propellers model? Better aircraft control? Optimizing for range and battery life doesn’t seem like a bad idea.

So there are two ways to control a rotor craft.

You can adjust the angles of individual blades, changing this angle multiple times each rotor sweep, as helicopters do. This is expensive, complex, things wear out, and a safety risk for the aircraft.

Or you can do what quadcopters do, direct drive the rotor and just adjust the speed of the entire rotor. This gets rid of both the Swashplate system and a transmission. It's lightweight, simple, and cheap. The problem is that it doesn't scale well to bigger rotors. When a rotor gets too big, it has enough inertia that you can't speed it up and slow it down fast enough to control your aircraft. Also, as you get bigger, you want a slower spinning rotor, and current electric motors aren't happy direct driving at that slower speed.

If you want to use the simple system, you have to use small rotors for now.

One additional point that is worth making regarding this rotational inertia in the blades is that this is what makes auto-rotation possible. In an engine-out situation a helicopter has a lot of energy stored in these blades and by conserving this as much as possible while 'falling' the pilot can pull up on the cyclic when close to the ground to trade the energy for enough lift to survive the crash. A direct-drive drone propeller cannot auto-rotate, and if for some reason it has an in-flight emergency that interrupts electrical power to the VTOL rotors it will plummet like a brick. I am not sure about the glide characteristics of those wings, but with all of the drag from the non-operative drone rotors I am guessing it would be somewhere between 'awful' and 'lawn-dart'.

Makes sense. Thanks for the explanation!

Most likely because of better control for drones. For this air taxi it may have more to do with noise.

That video is so cringy.

It is like those kickstarter videos, except they have something other than fluff to show.

What did you expect from a product called KittyHawk?

I'm not sure I get why that name would imply cringiness: isn't it named for the Wright brothers' proving ground? Is there a reference I'm missing?

They've picked up a lot from Apple Keynotes.

but with added cheesiness.

It seems the vertical take off blades become dead weight and air resistance in horizontal flight. Could they auto-rotate instead, aiding lift? Similar to how an auto gyro works. The wings would be the primary lift providers but why not take advantage of the vertical blades as well?

The key figure is the lift to drag ratio - as the lift needed is determined by the weight, then that divided by lift / drag gives you the thrust you need to keep flying. Autorotating small blades are not efficient lift generators, compared to fixed wings, which can have lift / drag ratios over 50 (though not on this machine.) Even partial lift from the rotors would reduce the overall lift / drag ratio. In addition, having the rotors generate lift would have an effect on the airflow over the wing, and probably be detrimental to its efficiency - it is bad enough that they are there at all, especially those in front of the wing.

Would a classic helicopter rotor overhead be a better solution, paired with those classic wide horizontal wings? Lift with the rotor, then thrust with the rear prop, using both wing and auto rotating overhead rotor combined for maximum lift.

Requires a tail rotor or similar. Perhaps the rear thrust motor or prop can be rotated sideways for takeoff? Now we’re getting complex, but not extraordinarily so.

Ape4 noted would add weight and complexity. Any more than eight small electric motors and props do now?

There have been several experimental aircraft like that [1] [2], but they are more like augmented helicopters than fixed-wing aircraft with VTOL. Aerodynamically, the arrangement is a biplane, and biplanes are rather inefficient because interference between the flows over the two wings reduces the overall efficiency.

Note that in the case of the Sikorsky S-72, the intent was to stop the rotor in cruise.

[1] https://en.wikipedia.org/wiki/Eurocopter_X3

[2] http://www.aviastar.org/helicopters_eng/sik_x-wing.php

Thank you. Looks like what I have in mind is called a Gyrodyne[1] or Heliplane[2]. I would expect it would have almost the same range and speed as an airplane with VTOL capabilities. As you mentioned, the interaction between the two flight surfaces may be too inefficient, but the X3 you linked to broke the unofficial speed record, so there's that.

[1] https://en.wikipedia.org/wiki/Gyrodyne

[2] https://en.wikipedia.org/wiki/GBA-DARPA_Heliplane

The rotate mechanism would add weight and complexity.

Disengaging the motors adds weight and complexity? Or would the props need to also be modified?

> No traffic lights

? only as long as there are just a few flying around. Once there are some with crossing routes you will need air traffic city rules as well.

I am really interested to see how that would pan out.

You don't need traffic lights on a 3D space. Air traffic rules are very different.

When your airplane is stacked in a holding pattern, waiting for clearance to land, it is essentially at a red light. If you and everyone else going to the same place are in electric airplanes, there is the potential for some real range anxiety.

Surely you've seen footage of swarms of autonomous drones flying around. They definitely will not need traffic lights.

I just gave a talk on flying cars. It turns out technical difficulty is not the reason we don't have flying cars, or self-driving cars.

Innovation is one way new technologies can change the world. For example, the reason we have skyscrapers is due to the elevator brake.

Elevators have existed in some form or another for over 2,000 years. But without the modern innovation of the elevator brake, nobody felt safe being hoisted by a rope up into the air, where a fall could kill you. And nobody looked forward to walking dozens of flights of stairs. A new combination of a spring, gravity, and a ratchet-and-pawl (all existing for over 2,000 years, the same as the elevator itself) gave humans the feeling of safely moving up and down in space that they didn't have before.

But innovation is not a guarantee of success. Electric cars have existed for 190 years. Their innovation, combined with the development of modern batteries, made them the most popular car by the beginning of the 20th century. But two decades later they disappeared, when cheaper, more convenient, more useful gas cars became available. It took another 60 years to develop a new production EV.

In comparison to land-based vehicles, drones are used to fly automated GPS-coordinated routes around the world every day. There are about 31.7 Million airplane flights over the USA every year. And even though 37,000 people die in car crashes every year, only 399 people died in air crashes in 2017 (world wide!). Not only are flying vehicles clearly safer than driving, we can very reliably coordinate flying vehicles.

So why don't we have automated flying cars? Nobody decided to build them. Until startups like this one do the actual hard, long-term, complicated work to coordinate all the necessary pieces, and can figure out how to make it both convenient and cost-effective, it just doesn't happen. And the same is true of self-driving cars.

Until someone decides to coordinate all the complicated parts to get it working, it doesn't exist. Sometimes this takes convincing society to make compromises - like, you don't get the "freedom" of piloting your own vehicle, unless you are very very well trained to do so. And sometimes it just takes lots of elbow grease. Personally, I think we need more of the former than the latter. But I'm glad this company is taking on both challenges.

What unless ? This is fun. I understand most of the engineering is in regression, but still making things that fly is fun. Only problem is money.

Firstly, I commend them for getting the vision started more than anyone else I’ve seen. It’s a V1 commercial product and they seem to have the resources to iterate. That being said, it’s not a very aesthetic craft. Sadly, they didn’t figure out how not to have wings. It’s like they took a Cessna/Piper and threw on 6 electric motors on each wing and a big battery pack and called it a flying car. Their former hovercraft product was much cooler!

Once this becomes practical with regulations worked out, there will likely be more people who choose to live in Napa Valley, Stockton, or Sacramento and commute to San Francisco or Palo Alto.

Real estate prices in those places might be affected a bit.

The same with New Jersey and Manhattan. What are some other areas that this might be the case?

Once the direction becomes clearer, perhaps someone should start an REIT with a focus on arbitraging transportation revolution.

Ummm, are there flight corridors defined for low flying aircraft? You can't just fly in a straight line everywhere. You can't just fly over a densely populated area and how do you avoid crashing into other flying taxis?

You read the comments and you think everybody gets it, but then nobody gets it.

Google must be too early.

Anyone know how much this costs per mile?

Less than gas car.

solutions for the .01%

It always starts with them before it trickles down to the rest of us. Let's hope they use it and beta test it for us.

Nah, let's hope one of them gets an itch to become public transportation's savior.

it isnt sexy enough and wont make them any return. completely agree with you. its a total waste of resources. never gonna happen

What's the utility of using electric motors over turboprops, etc? Is it just the simplicity factor?

Another flying car company. Many have tried. Before doing uber-air, first perfect the flying car as an aircraft. That hasnt happened. Then we can talk about the robot at the controls or the app that will summon it.

Get all the air safety stuff done. Biuld a few thousand non-experimentals. Have people actually fly these things daily. Then worry about disrupting the car market.

I think it being autonomous is integral to it being a "success". Energy density is still a major limitation and doing away with the pilot can be one way to make the numbers work economy wise. A flesh and bone pilot will come at a substantial weight penalty, effectively reducing the utility of this 2 seater by half.

As a licenced pilot myself, I am with you, however. Would not climb into this death trap as a self loading freight any time soon.

Seeing the rates of "single vehicle accidents" in small aircraft piloted by amateurs, I'm happier with the autonomy.

Also, autonomy in the sky seems easier than autonomy on the ground.

If Thrun is involved, chances are it will work pretty well...

> Also, autonomy in the sky seems easier than autonomy on the ground.

This is debatable.

A car has only 1 degree of freedom. An aircraft typically has 3 degrees of freedom.

A car rests on solid ground. An aircraft is submerged in a fluid medium.

A ground vehicle can adjust it's speed to the conditions, if necessary slow down if confidence levels get lower, or even go backwards. An aircraft is typically subject to an aerodynamic envelope.

As for the sky being empty, take a look at this harrowing story of a biz jet encountering the wake turbulence of a A380. Airframe written off, crew earn their lifetime salary. Autopilot took 13 seconds to conk out.


Turns out modern aircraft following airways to a precision of mere meters has increased such incidences. In the olden days pilots where often a bit off the track. To simulate this sloppiness in flying rigor, a thing called SLOP has been conceived, for Strategic Lateral Offset Procedures.

To be fair, this one looks significantly more production ready than all other attempts at a 'flying car' I've seen. It does seem like a compelling replacement for e.g. private jets or helicopters (and not specifically for cars yet)

All I can think about is Clifford Simak's "City."

leave it to the dogs

Finally we are getting flying cars instead of 140 characters.

I must say I'm against this development. First of all, even if electric, this is certainly a very inefficient way of transportation that will 'waste' a lot of energy to transport maybe 4 people.

The resulting price of this technology will result in the 99% stuck on the ground while the only te 1% can afford the fare.

And even if it becomes a regular mode of transportation, do you really want these planes to fly over your apartment/house every few minutes? They might be more quiet than a Cessna but they wll certainly still be disturbing

I agree. People talking about flying cars sound a lot like people demanding faster horses. Or flying horses.

I do not think the American dream of a private car scales too well to the future, be it with rubber wheels or tiny propellers. Especially given the population growth.

Instead, a brief visit to Singapore, for example, will convince anyone what the future of transportation looks like. A public transport system, enabling a lifestyle that makes cars redundant.

> Instead, a brief visit to Singapore, for example, will convince anyone what the future of transportation looks like. A public transport system, enabling a lifestyle that makes cars redundant.

Living in Singapore, I agree with what you say, but in this future, there will be a lot of whining, too:


Instead, a brief visit to Singapore, for example, will convince anyone what the future of transportation looks like

It might have convinced you, but it won't "convince anyone", or the majority of people.

Being a huge advocate for public transportation, I have to admit that it doesn't translate that well to many American cities. Most American cities have too low density.

There is another issue I've noticed with public transit in the US which I haven't experienced elsewhere and have no good explanation for: Too frequent stops. May it be buses in LA or light rail in SF or PDX, they constantly are stopping. It seems like there is a stop on at least every other block making it super slow to go cross town.

Great for dense urban areas. Not so much for the remaining 97% of the Earth’s surface. If the future of transportation means packing myself in a crowded city, count me out. I’ll keep my car, thanks.

The point of flying cars is that they would be cool to fly. I mean, at least _if_ you get to fly them, as opposed to you just being their cargo.

How safe is Singapore public transportation and walking?

The reason I ask is that neither are as safe as driving here in the US which i consider a major blocker in the public transportation utopia people keep dreaming up.

Relevant discussion I have had about this topic: https://news.ycombinator.com/item?id=16462803

> How safe is Singapore public transportation and walking?

Extremely safe. Even the whiniest people in Singapore (and that's a high bar to clear) will never say that Singapore is unsafe.

Once in a while I see videos of cars not stopping in front of a pedestrian crossing. These posts result in a universal condemnation.

Also note that the UK-style pedestrian crossings include a buffer space next to the actual crossing.

In terms of public transportation, you have the subway (MRT), the light rail (LRT), and the buses. All new, and most of the MRT plus LRT are automated.

Additional aspect is drink-driving. The alcohol is also heavily taxed (almost Demolition Man style: "x is not good for you. What's not good for you is illegal") and the way the government views drugs is clarified in the disembarkation cards saying "Death to drug traffickers" (and they actually mean it), and with the combination of high availability of public transport complemented with cheap taxis / ride-sharing and low availability of intoxicating the DUI is pretty much non-existent.

In the US, the sidewalks are scarce in many places. But that's pretty unique, you don't need to go to Singapore to see streets with normal sidewalks.

I have a hard time believing that public transportation or walking are more dangerous than driving in the US or elsewhere.

Do you have any statistics on walking or public transit safety? I couldnt find any, though car safety is very accessible.

edit: It seems the vast majority of pedestrian accidents are because of collisions with cars. In a future with more public transport and walking, they will be even safer.

I should have clarified that the safety I am referring to is from other people in the form of harassment and assaults.

The reason public transport and walking can be unsafe is the us has deliberate policies making it so. We have more police presence on roads, and less on transport. We have urban design explicitly supporting the car, with human unfriendly design. Look at how many roads have no side walks or bike paths. A 1 mile journey in many areas is unsafe without a car. We need a massive rethink of how we design cities, and there are issues at all levels of government. Federal government tax incentives favor single family detached homes, and Grant money goes towards expanding infrastructure in an unsustainable and unsafe manner.

I agree with your opposition to this development with respect to people moved per unit of energy consumed. I think development funds are much better spent on improving the efficiency, reliability, and capacity of mass transit systems for large and crowded urban areas. However, that's not really fodder for sexy startup material.

Additionally, if these are widely adopted, I can imagine a highly-crowded Class G (or D, if near an airport -- and how do you establish two-way comms between ATC and an autonomous flying taxi?) airspace ending badly for passengers or bystanders in crowded metropolitan areas. This may be why KittyHawk has done their R&D in New Zealand, rather than in the US under FAA regulations.

The way it will work on the US based on what Uber and others are talking about. Is a special corridor where only autonomous traffic is allowed. This planes allowed on this corridor will have digital air traffic controllers and only be allowed if they have certain amount of capacity similar to ADS-B mandate in the future.

This allows the plane to all fly and not hit each other and pilots won't be allowed in that corridor.

I'm personally against it because I don't want anything to fall down into my garden or on my head in case of a failure.

I'm pretty sure this is a literal "Not In My Back Yard" comment.

I'm okay with it. Yes it will be for the 1% for a long time, but so were trains and cars and airlines...

But how does this system scale? Thousands of these simultaneously in the air above cities? The noise must be quite something.

I think it's a novel helicopter replacement idea, but not really anything for mass transportation.

These would be extremely quiet while cruising but likely pretty loud on take off. The latter is moot since that's happening at an airport.

They're supposed to be able to land and take off buildings I thought?

Although autonomous doesn't solve the failure problem, it does (for the most) part solve the crazy/incompetent problem of the past, future visions of flying cars for everybody.

You realize someone can probably crash their car into your garden, right?

Can't you say the same about helicopters and airplanes?

Yup. But probability is close to Zero.

Do planes often fall on your head?

> Do planes often fall on your head?

No, but once per week I see a broken car on a motorway on my commute.

Nope. Given the number of planes in the world the probability of that happening is close to Zero. But a lot of birds has pooped on my head. The more KittyHwaks and other mass used flying cars in the air the more the probability of one falling on your head.

I don't think it would be acceptable for an aircraft like this to have a failure rate comparable to a birds poop rate.

If it reduces the din of the awful noise of living anywhere near to a helipad in the south west of London, just so rich kids can come and go as they please, then it's worth it.

The choppers are already there, so there's already the risk of something falling out of the sky.

It's true that they should not be adopted en masse, but in some cases, it is very useful:

* transportation across mountainous terrain - it will actually increase safety

* a few tightly controlled shuttles in gridlocked megalopolises like those in Asia with nightmarish traffic

Basically, taking over the role of the helicopters, but safer and more affordable.

I would, however, prefer fewer smaller bus-sized vehicles.

These would work great in Fiji flying tourists from the international airport on the main island to the dozen or so little resort islands nearby.

And since a significant proportion of our electricity is generated by hydro power, could be almost carbon neutral travel.

I don't fear flying cars. I fear flying car crashes. Instead of a fender bender they "land" in your bedroom.

Do you fear small airplanes (which have been flying over your house for almost a century) too?

Ever heard of a ballistic parachute? Not a 100% solution of course, but then again zero customers died in all passenger aircraft flights last year.

That’s saying a lot when every single day, there are times when there are over a million people simultaneously sitting in chairs in the sky

I believe it was zero deaths on commercial jets last year, but when comparing that safety record to these smaller craft, it's a category error. Light planes are generally less safe than commercial jets per miles traveled.

Five people just died in a NYC heliopter crash on sunday: https://www.cnn.com/2018/03/11/us/new-york-city-helicopter-a...

> but then again zero customers died in all passenger aircraft flights last year.

This isn't even remotely accurate.

Also, even when a BRS deployment goes well, there's a good chance that the aircraft is coming through someone's roof if flying over a populated area.

Typical cynical hacker news comment. Have you seen any numbers wrt mileage? Do you know if this will be debuted as a taxi which can transport users vs. something one can own? Have you seen any wrt emissions vs. a normal suv which carries a family of 4?

I am amazed how you can come to this conclusion without knowing anything about the product.

I’m amazed you missed the parts where everyone in the video referred to it as an “air taxi”.

I did not. The person who was commenting before me did.

What about in places like Bogota where the rich are already using helicopters to travel the city? Surely a service like this opens air travel up for a larger audience.

And as for efficiency, again, places like Bogota or Guatemala City are so congested all day/evening, surely idling in your car for 1+hr to go a few miles is not efficient.


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