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Electric / hybrid aircraft propulsion (NOT cars)

The end result is that the batteries will outlast the car, several times over for most cars.

That would defy the laws of physics and everything known about batteries… are you sure the manufacturers have not implemented some sort of VW-style software cheat in the capacity display? If VW did it, and most other car manufacturers did it too (but for various reasons it is mostly VW which have taken the heat for it) everybody might be doing it.

An easy way to do it would be to conceal any degradation, until it reaches say 80%. In terms of marketing, providing all the manufacturers are doing the same, this would work perfectly.

OTOH if the battery capacity is never explicitly revealed, most people won’t be able to tell.

I know electric car charging is done a lot more intelligently than consumer LIPO battery charging, but I don’t see where the apparently several orders of magnitude improvements in battery life might have come from.

Administrator
Shoreham EGKA, United Kingdom

As far as the used battery range is concerned, this is exactly what they do. And I don”t think is is cheating, at least not protecting the battery from undesirable deep discharging and overcharging by having 0 and 100 percent at levels that protect the battery, rather than at levels that are theoretically possible, as long as the capacity is advertised using that operational range.

But in general, they do not hide degradation with an artificial 100 percent point that is not shown – because that would reduce range indication for new cars, and (mostly unjustified) range anxiety is more of a problem for users than slow battery degradation.

BTW – there is a lot of progress in that area, not only because of better thermal management and battery cooling, but also because of development in battery chemistries.

For cars, all tbis is merely an economic problem that is becoming less and less relevant as battery prices decline due to scale effects. A battery that lasts for 200-300 thousand miles or more and then gets replaced isn’t that much of an issue, and it wasn’t that long ago that cars with that sort of mileage were considered scrap.

Biggin Hill

Peter wrote:

re you sure the manufacturers have not implemented some sort of VW-style software cheat in the capacity display?

They have indeed but it’s very different than what you think. There are standards for range. In Europe, the NEDC standard is used. It’s overly optimistic, almost pure fantasy and will be replaced now by the WLTP standard. In the US they use an EPA standard. It’s much more realistic than NEDC, but not as good WLTP.

All these standards are averages. The one single most important factor is temperature. This affect, charging (speed and max charge), use (how much power is drawn, range). The reason is that it’s also the most important factor for how long they last. When it’s cold, the range is reduced to almost half (-20 C compared with +20), and to charge it takes 2-3 times longer. A battery is maybe never charged more than 80-90% of max and never discharged to lower than 10-20 %. Temperature will decrease that range, and also decrease the max in/out put. Maybe as the car gets older, or measuring the condition, these ranges increases, I don’t know. It’s very “fluid” stuff with no correct answer, only approximations.

Anyway, the guaranty on my eUp is at least 80% battery capacity after 160k km, or after 8 years (regardless of how it’s charged and how it’s used). 80% of what? I don’t know. My car was manufactured long before long term effects of use was known, so these numbers are probably just best guestimates, but conservative. We have a large fleet of Tesla Taxis in Norway, as well as a few Leafs. The real life experience shows 500k + km as no problem at all. Very few drives their own personal car that far, so it’s all rather clear how long they last. The only other factor is age, but the first Teslas are already 6-7 years old. How the batteries stand up after 20 years is of course unknown except in theory, but a car isn’t made to last for 20 years in daily use.

The elephant is the circulation
ENVA ENOP ENMO, Norway

There is a whole fleet of electric cars running up an incredible mileage every day:
tesloop mileage

EBKT

Aveling wrote:

I was told that the two packs are swappable, and certainly seemed to be made that way, with side access doors. But spanners appeared to be needed. They weigh about 30 Kg each.

This might be a US-specific issue, the guy also mumbled something about liability. It would certainly make more sense to have swappable packs in order to get the bird in the air again presto.

This article asserts that 100% electric VTOL is likely to prove impossible, and that a hybrid approach may be needed.

I am not surprised.

Administrator
Shoreham EGKA, United Kingdom

I will be quite surprised if 100% electric VTOL proves to be impossible, especially as it is clearly in existence today. Agree, hybrid will be the approach needed for extended range or endurance. The advantages of the electric propulsion system remain even with the additional complexity, combustion, fuel, vibration, waste heat etc.

The larger paradigm shift, away from legacy designs such as R22 exemplifies, is to be applauded and is way overdue. The helicopter is a marvelous multi-role utility, the new eVTOLs are necessarily constrained in role, but the viable roles are very suitable for new transport ecosystems and are perhaps more marvelous. The weight of research and industry activity is telling. 20 years ago I heard the same negative assessments of autonomy / electric / vtol / drones. Pretty sure that paradigm changed.

Here is some more background;

Boeing conservatism,

and

Broad Research and Industry Presentations

Other

Very important to read this document from Airbus too.

Although you may have enjoyed the current paradigm of effortless and safe GA for hundreds of years, things do tend to change in the aviation industry.

Other

That’s an interesting article from Airbus ( local copy ) … one has to start somewhere, identifying the challenges.

the current paradigm of effortless and safe GA for hundreds of years

A bit less sarcasm perhaps? Sarcasm and irony don’t travel well over the internet.

Administrator
Shoreham EGKA, United Kingdom

For those of you who want to follow what’s buzzing this may be interesting, updated 4 times per year:

http://www.e-flight-journal.com/efj3j2018-efj2besichert.pdf

Private field, Mallorca, Spain
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