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The age of electric flight is finally upon us

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Re: The age of electric flight is finally upon us

#171

Post by upofadown »

marvin wrote: post #20

I fly gliders. Absolutely can't wait until my local club finally decides to get an electric single-seat self-launching glider, preferably with enough endurance to do some additional tens of kilometers after the launch, in order to avoid landing out if the weather dies out. It's a gamechanger with regards to both costs and convenience. No towplane, towplane pilot, no outlandings.

Self launching on batteries means carrying around a fair bit of dead battery weight for the entire flight. Electric sustainers (can't take off but can stay up) are pretty interesting because gliders take hardly any power to fly level. Example:

* http://front-electric-sustainer.com

All this electric vehicle technology works really well for electric glider winches. You can get a whole lot of peak power off of a battery so you don't need a huge electric power feed.

Re: The age of electric flight is finally upon us

#172

Post by rootusrootus »

rbanffy wrote: post #111
usrusr wrote: post #65

Earlier quoted context omitted.

The 80% figure are flights longer than 1500 km. 1500 and less are the 20%. So even if all those flights were switched to magic zero emission electricity, the aggregate improvement over the whole industry would barely beat the relative improvement between a 737 NG and a MAX. (yes, this is an apples to orchards comparison)

To be fair, the MAX has been zero emission for a couple months now.

That's not strictly correct. There are MAX's flying every day. At this moment, there are two in the sky.

Grounded from carrying passengers, but not grounded entirely from flying, and certainly emitting in any case. The two on the map now are out of Boeing Field.

Re: The age of electric flight is finally upon us

#173

Post by godelski »

Robotbeat wrote: post #160
namirez wrote: post #106

As others have noted, electric flights require a major breakthrough in the battery technology. Here are energy density numbers for gasoline, jet fuel, and lithium-ion batteries: Gas and jet fuel specific energy density ~= 45 MJ/kg; Lithium-ion specific energy density Even worse, a jet engine is much better at generating power. A modern high-bypass turbofan engine can generate 10 kW/kg whereas an electric motor is aro…

This is constantly repeated, but it's not true. I work in the field of electric motors for electric aircraft, and the amount of nonsense constantly repeated on the Internet about how electric flight cannot be done without a breakthrough is breathtaking. Electric motors can achieve FAR greater than 1kW/kg. Here's one used sometimes on electric aircraft capable of 10kW/kg, same as a jet engine: https://emrax.com/produc…

I haven't seen the 1.5MJ/kg batteries but that is still pretty far from 10MJ/kg. Your first paragraph seems pretty hostile considering this fact.

Look, we all want electric aircraft. I can't wait for them. But to say that it doesn't require a major (honestly several major) breakthrough (s) is an extreme understatement and does not requisite the hostility you are giving.

Re: The age of electric flight is finally upon us

#174

Post by sunstone »

namirez wrote: post #106

As others have noted, electric flights require a major breakthrough in the battery technology. Here are energy density numbers for gasoline, jet fuel, and lithium-ion batteries: Gas and jet fuel specific energy density ~= 45 MJ/kg; Lithium-ion specific energy density Even worse, a jet engine is much better at generating power. A modern high-bypass turbofan engine can generate 10 kW/kg whereas an electric motor is aro…

Your analysis would be more compelling if you added some $$$ here and there. The savings in maintenance and fuel are really what's driving this technology.

Re: The age of electric flight is finally upon us

#175

Post by NickM »

rootusrootus wrote: post #30
NickM wrote: post #17

Earlier quoted context omitted.

Yeah I have wondered about this option as well. Hydrogen fuel cell cars make very little practical sense for a lot of reasons, but most of those reasons don't seem to apply so much when you're dealing with air travel: - It'll be a long time before fuel cells are cost competitive with gas or electric cars, but for planes the cost of fuel and operation is much more significant than with a car, so the upfront cost for b…

> 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.

Thanks for the info! I stand corrected on that point.

Re: The age of electric flight is finally upon us

#176

Post by Robotbeat »

godelski wrote: post #173
Robotbeat wrote: post #160

Earlier quoted context omitted.

This is constantly repeated, but it's not true. I work in the field of electric motors for electric aircraft, and the amount of nonsense constantly repeated on the Internet about how electric flight cannot be done without a breakthrough is breathtaking. Electric motors can achieve FAR greater than 1kW/kg. Here's one used sometimes on electric aircraft capable of 10kW/kg, same as a jet engine: https://emrax.com/produc…

I haven't seen the 1.5MJ/kg batteries but that is still pretty far from 10MJ/kg. Your first paragraph seems pretty hostile considering this fact. Look, we all want electric aircraft. I can't wait for them. But to say that it doesn't require a major (honestly several major) breakthrough (s) is an extreme understatement and does not requisite the hostility you are giving.

The key thing often missed is that jet fuel is much better than it needs to be, particularly for domestic flights.

Batteries don't need to equal jet fuel in order for electric air travel to be viable.

We have airplanes capable of 15,000km trips. But we were making transatlantic flights back when our aircraft could only do about 2000km range reliably. Going from from Labrador, Canada to Greenland to Iceland to England, the minimum hop distance is about 1200km. https://en.wikipedia.org/wiki/Transatlantic_flight#/media/Fi...

I don't expect electric air travel to operate Transatlantic flights with 1.5MJ/kg batteries as major competitor to jet travel unless there's a very hard clampdown on greenhouse gas emissions. The logistics of adding major stops in Greenland and northern Canada to enable transAtlantic electric flight just likely won't be worth it. But for domestic flights (which are the majority of flights), electric air travel will be common.

Source for ~1.5MJ/kg batteries:

https://sionpower.com

https://oxisenergy.com

Re: The age of electric flight is finally upon us

#177

Post by gameswithgo »

guntars wrote: post #157
gameswithgo wrote: post #108

Earlier quoted context omitted.

Carbon sequestration and biofuels that are actually carbon neutral may be similarly implausible.

What’s the reasoning behind your statement? I think both are already being done, the economics are just not there yet. Digging up free energy from the ground is just too cheap.

The scale of co2 that would need to be sequestered is massive, I don't think anyone has a vaguely viable plan of how that would be done.

Most attempts at biofuel are not even net positive on energy. if we did get there then the question is how much forest do we have to clear to grow biofuel AND eat, and what net effect does that have on co2.

Hard problems all around.

Re: The age of electric flight is finally upon us

#178

Post by fdjlasdfjl »

Patrick_Devine wrote: post #63
iambateman wrote: post #10

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…

That's why I fly Harbour Air. Downtown Vic to Van in 25 minutes. I can't wait to fly electric.

Re: The age of electric flight is finally upon us

#179

Post by 7952 »

marcosdumay wrote: post #79
mannykannot wrote: post #21

A battery fire is a scary prospect unless the fire can be effectively contained and the hot gases vented (I don't suppose extinguishing one is likely to be an option.) There has been at least one crash involving fire, though I have not been able to find out if it was a propulsion battery fire. [1] In Eviation's Alice, the failure or shutdown of one of the wingtip's motors would require the shutdown of the other, on a…

Why so few motors? Electric motors have low cost and low maintenance, so I would expect electrical planes to have many of them. Overpowering the motor during the entire take-off would bring a high risk of having it fail too. But overpowering it to overcome the most common obstacles is perfectly viable in an emergency. Anyway, about fires, they are a reasonably easy problem to deal with. Fires on liquid are much more…

Larger propellers are more efficient than smaller which could make a difference if each motor drives its own propeller.

Re: The age of electric flight is finally upon us

#180

Post by fdjlasdfjl »

drainge wrote: post #159
Patrick_Devine wrote: post #63

Earlier quoted context omitted.

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…

Unfortunately the battery weight is also currently prohibitive for small companies such as Harbour Air and Mokulele. Several weeks before the Harbour Air / MagniX announcement I ran through an exercise to determine the range/payload of an electric Cessna 208 (Caravan) for a typical flight profile here in the bay area: the daily FedEx flight from Oakland International to some nearby city, such as Petaluma. This involv…

They're island hoppers. Victoria to Saltspring would probably fit in that 9 minute threshold, and 30 minutes is about the longest flight they have.

Wondering if you know if there are different regulations for float plane reserves while flying over water?

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