Cora – Kitty Hawk's prototype air taxi [video] • Hacker News Board

Re: Cora – Kitty Hawk's prototype air taxi [video]

#161

Post by seanmcdirmid » Tue, Mar 13, 2018, 2:54 PM UTC

CodeWriter23 wrote: post #150

seanmcdirmid wrote: post #114

Earlier quoted context omitted.

> 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%. https://www.eia.gov/energyexplained/index.cfm?page=electrici... 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.

Re: Cora – Kitty Hawk's prototype air taxi [video]

#162

Post by [deleted] » Tue, Mar 13, 2018, 2:55 PM UTC

cowsandmilk wrote: post #85

danielvf wrote: post #47

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 effic…

> 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 sho…

[deleted]

Re: Cora – Kitty Hawk's prototype air taxi [video]

#163

Post by ZeroGravitas » Tue, Mar 13, 2018, 2:56 PM UTC

syntaxing wrote: post #147

BatFastard wrote: post #136

Earlier quoted context omitted.

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.

Re: Cora – Kitty Hawk's prototype air taxi [video]

#164

Post by kolinko » Tue, Mar 13, 2018, 2:57 PM UTC

Kequc wrote: post #107

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 en…

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.

Re: Cora – Kitty Hawk's prototype air taxi [video]

#165

Post by sangnoir » Tue, Mar 13, 2018, 2:57 PM UTC

syntaxing wrote: post #118

danielvf wrote: post #47

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 effic…

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).

> 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.

Re: Cora – Kitty Hawk's prototype air taxi [video]

#166

Post by pc86 » Tue, Mar 13, 2018, 2:59 PM UTC

danielvf wrote: post #47

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 effic…

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.

Re: Cora – Kitty Hawk's prototype air taxi [video]

#167

Post by nopinsight » Tue, Mar 13, 2018, 3:01 PM UTC

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.

Re: Cora – Kitty Hawk's prototype air taxi [video]

#168

Post by patch_collector » Tue, Mar 13, 2018, 3:02 PM UTC

Kequc wrote: post #107

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 en…

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.

https://phys.org/news/2017-11-emissions-worldwidegas-battery...

Re: Cora – Kitty Hawk's prototype air taxi [video]

#169

Post by fastball » Tue, Mar 13, 2018, 3:04 PM UTC

nradov wrote: post #82

danielvf wrote: post #47

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 effic…

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.

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.

Re: Cora – Kitty Hawk's prototype air taxi [video]

#170

Post by thaumaturgy » Tue, Mar 13, 2018, 3:05 PM UTC

ethagknight wrote: post #71

danielvf wrote: post #47

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 effic…

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,…

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