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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]

#151

Post by masklinn »

davidedicillo wrote: post #127
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…

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

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

#152

Post by javiramos »

danielvf wrote: post #64
javiramos wrote: post #52

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…

Makes sense. Thanks for the explanation!

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

#153

Post by rolha-capoeira »

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…

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.

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

#154

Post by mrep »

jp555 wrote: post #39
coldcode wrote: post #20

Earlier quoted context omitted.

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

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

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

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

#155

Post by syntaxing »

brunosutic wrote: post #26

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.

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.

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

#156

Post by [deleted] »

danielvf wrote: post #148
willglynn wrote: post #138

Earlier quoted context omitted.

> [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. Mayb…

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

[deleted]

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

#157

Post by syntaxing »

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.

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.

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

#158

Post by willglynn »

danielvf wrote: post #148
willglynn wrote: post #138

Earlier quoted context omitted.

> [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. Mayb…

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.

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

#159

Post by Kalium »

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…

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.

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

#160

Post by ransom1538 »

willglynn wrote: post #138
ransom1538 wrote: post #70

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.] https://www.youtube.com/watch?v=kQyrPVIIQdE

> [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. Mayb…

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