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

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

#211

Post by mrep »

aqme28 wrote: post #174
mrep wrote: post #143

Earlier quoted context omitted.

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

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.

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

#212

Post by mnw21cam »

assblaster wrote: post #119
syntaxing wrote: post #106

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…

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.

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.

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

#213

Post by nascar_is_bad »

shortoncash wrote: post #131
nascar_is_bad wrote: post #122

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.

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

#214

Post by danielvf »

nickbauman wrote: post #209
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…

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 es…

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.

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

#215

Post by greeneggs »

fastball wrote: post #184
sjs382 wrote: post #140

Earlier quoted context omitted.

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...

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

#216

Post by cbr »

nickbauman wrote: post #209
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…

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 es…

     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.

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

#217

Post by danellis »

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…

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.

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

#218

Post by sixbrx »

pc86 wrote: post #172
danielvf wrote: post #124

Earlier quoted context omitted.

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 fu…

> 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 a…

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

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

#219

Post by notheguyouthink »

gambiting wrote: post #194
thaumaturgy wrote: post #170

Earlier quoted context omitted.

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:/…

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.

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.

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

#220

Post by rukittenme »

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…

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.

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