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The age of electric flight is finally upon us

bbc.com

141–150 of 272 posts

Re: The age of electric flight is finally upon us

#141

Earlier quoted context omitted.

> if a plane crashes there's a good chance everyone dies anyway That's actually not the case. Overall your odds of surviving an accident in a plane are something like 95%. Still above 50% for "serious" incidents. Sure, if the plane drills the ground everyone is going to die, but planes crash somewhat regularly with most/all surviving.

Also one of the most dangerous places to be in a plane, statistically, is on the ground. A surprisingly large proportion of historic fatalities in air accidents have been crashes on the taxiway or runway between two aircraft (eg plane lands on top of another or taxis across a live runway when it shouldn't do).

There's a lot more stuff to hit on the ground than there is in the sky.

Re: The age of electric flight is finally upon us

#142

https://twitter.com/BenBrelje_says/status/106484220091004108... https://twitter.com/BenBrelje_says/status/106485722028904038... https://twitter.com/BenBrelje_says/status/106491195862390374... To recap, based on financial statements the company: used to be a "waste management" company that failed and was sold as a "public shell" to enable the formerly private company to go public and sell shares (the waste management…

Having recently watched several engineering videos on the limitations for electric flight I was surprised to see this article. As your comment points out, it certainly appears too good to be true.

Re: The age of electric flight is finally upon us

#143

From the article: conventional fuel for a 100 mile flight costs $400, while electric energy would cost $12. This seems like such a tremendous difference that the market would be in an arms race to make it a reality. Especially considering electric motors have fewer moving parts and so require less maintenance. Oh and it would be so quiet.

It's a game changer for airlines such as Harbour Air in British Columbia and Mokulele Airlines in Hawaii. These are small regional airlines which operate from the water or from small airports with flight times usually less than an hour, and most of their operational expenditures are in fuel costs. Typically for these airlines you show up 15 minutes before the flight and there is no security screening, so it's very ha…

How long would recharging take?

Re: The age of electric flight is finally upon us

#144
post #119

Earlier quoted context omitted.

>> off-field forced landing that went badly. Parachutes. They are now a very practical option for GA aircraft. More than a few cessnas have been saved. The concept of "off-field forced landing" should too be going away. https://brsaerospace.com/cessna-faqs/ " Q. How many aircraft saves are credited to a BRS Whole Aircraft Rescue Parachute System? A. As of August 2017, 376 ."

"Q. How much damage will be done to my plane if I land it with a parachute? A. In all likelihood the aircraft will suffer some significant damage. The terrain where you land will affect this greatly. Though the extent of damage has varied from plane to plane, most GA aircraft that have come down under a BRS deployment have eventually (or will soon) fly again." Call me a skeptic until they provide hard numbers and det…

If the plane is designed to take a BRS then there is a good chance that after some (admittedly costly) repairs it will take to the air again.

A 172 or similar that has been retrofitted with a BRS? Yeah, not so much.

Re: The age of electric flight is finally upon us

#145
post #73

This plane wouldn’t even be capable of getting me to the closest aircraft hub at its maximum range, let alone with a safety margin (I live an hour and a half, by jet, from Denver). Not to mention it will be slow and badly impacted by storms (since it has an operating ceiling of 10,000 ft).

There are flights shorter than 650mi.

They'd have to be shorter than 400 miles to be safe. At which point, it's probably just as fast to drive (or faster, given it's a prop plane whose speeds are in the ~200mph range).

Re: The age of electric flight is finally upon us

#146

Earlier quoted context omitted.

That's probably OK: having to replace a motor would be a small cost compared to that of an off-field forced landing that went badly.

>> off-field forced landing that went badly. Parachutes. They are now a very practical option for GA aircraft. More than a few cessnas have been saved. The concept of "off-field forced landing" should too be going away. https://brsaerospace.com/cessna-faqs/ " Q. How many aircraft saves are credited to a BRS Whole Aircraft Rescue Parachute System? A. As of August 2017, 376 ."

In addition to the point verelo raised about the repair/replacement cost of having used a parachute (vs. replacing a motor), I was thinking specifically of a wingtip-motor failure at takeoff (typically the worst-case scenario), possibly too low for a parachute (some figures here: [1]).

This is a 9-passenger airplane, maybe too large for current recovery parachutes? (though I imagine that will change.)

[1] https://www.cirruspilots.org/copa/safety_programs/b/pull_ear...

Re: The age of electric flight is finally upon us

#147
post #28

This plane wouldn’t even be capable of getting me to the closest aircraft hub at its maximum range, let alone with a safety margin (I live an hour and a half, by jet, from Denver). Not to mention it will be slow and badly impacted by storms (since it has an operating ceiling of 10,000 ft).

It's a prototype.

Which indicates that the "age of electric flight is not finally upon us". People have been putting electric engines in gliders for a lot more mileage and flight time for years.

Re: The age of electric flight is finally upon us

#148
post #2

I'm surprized hydrogen fueled flight isn't looked into more. Hydrogen can be produced using electrolysis and it's packs significantly more energy per weight even than kerosene. The main drawback is the low density which would require larger fuselages, but that should be offset by the significantly lower weight.

My dad worked at a company that was researching hydrogen (probably for scram jets). Problem he said with hydrogen is the size of the fuel tanks starts negatively impacting the amount of payload you can carry.

Re: The age of electric flight is finally upon us

#149

https://twitter.com/BenBrelje_says/status/106484220091004108... https://twitter.com/BenBrelje_says/status/106485722028904038... https://twitter.com/BenBrelje_says/status/106491195862390374... To recap, based on financial statements the company: used to be a "waste management" company that failed and was sold as a "public shell" to enable the formerly private company to go public and sell shares (the waste management…

Those tweets have been deleted, and where’s the evidence of these claims?

Yeah, I see this kind of thing repeated any time Eviation comes up.

I don't believe them. The design is sound, if radical in the decision to be mostly-battery. And I think that's partly why people are so skeptical: it definitely goes counter to the industry grain. But it IS the right way to build a serious electric aircraft for regional/commuter passenger travel. Pressurized, extremely high lift-to-drag ratio, very high battery mass fraction, focus on high propulsive efficiency by ingesting boundary layer with the pusher propeller and countering wing-tip vortices with wing-tip propeller. The passenger count is also right, at the limit of FAR-23, allowing you to use a single pilot.

The only thing I would do differently is probably have a higher cruise altitude and higher aspect ratio wings (and probably counter-rotating dual-motor pusher propellers) instead of using wing-tip propellers and gettin, but theirs is a valid design choice as well.

So much group-think especially with the larger aerospace companies. They insist on hybrids for flight (notice how whenever Airbus or Boeing buy one of these exciting electric flight startups, they all of a sudden switch to hybrid?), which ends up compromising the design and adding a whole new propulsion system to validate and certify. Others have a valid approach of retrofitting electric onto older airframes, but that is not going to get anywhere near the operational efficiencies of a clean-sheet design. And still others insist on VTOL, but I have my doubts as to whether the focus on VTOL by so many of these electric flight startups is going to really be worth it in the end except for niche cases.

Re: The age of electric flight is finally upon us

#150

Earlier quoted context omitted.

That's probably OK: having to replace a motor would be a small cost compared to that of an off-field forced landing that went badly.

>> off-field forced landing that went badly. Parachutes. They are now a very practical option for GA aircraft. More than a few cessnas have been saved. The concept of "off-field forced landing" should too be going away. https://brsaerospace.com/cessna-faqs/ " Q. How many aircraft saves are credited to a BRS Whole Aircraft Rescue Parachute System? A. As of August 2017, 376 ."

Save someone some Googling:

https://www.youtube.com/watch?v=jgfG2DfPB6I

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