News: 1591102243

I really don't see 'e'aviation really taking off before there is a safer alternative to several thousand 18650s soldered into place, both toxic and horribly flammable, you wouldn't want that having a firey end near you.

If something like vanadium redox gets a bit further with higher energy densities it could provide a way forward, being non toxic and not inclined to burst into flames when you poke a hole in it, it may provide an answer.

5-8kW installations are already available for domestic installation as back up or PV storage and it has little to no discharge over time on standby.

Sure. Because everybody knows that jetfuel doesn't burn.

*cough* TWA Flight 800 *cough*

There are additives in jet fuel to reduce the fire risk in the event of an accident. Of course it doesn't completely prevent fire but it is not as bad as you might think.

Lithium, however, Will, ignite when exposed to air to the point where it can be explosive and we are talking here about enough energy to lift a plane. That is without beginning to consider toxicity and environmental damage involved in the extraction of lithium.

True jet fuel does contain additives, but I'd still defend with the point that the entire PURPOSE of jet fuel is to burn, albeit in a controlled manner rather than explosively.....but I'd also counteract that well designed batteries keep the cells apart in order to prevent thermal runaway. Presumably they'd also be kept in a sealed compartment which only vents to the outside in the event it's needed.

Modern jets are already full of lithium batteries anyway - just look at the Dreamliner.

The point I'm trying to make is that most methods of propulsion are dangerous in principle simply because they pack a large amount of energy into a small space...that's kind of how fuel works. But any technology has risks and workarounds...they've had decades of practice to make jet fuel based systems work relatively safely, and the same will happen with electrical power. It's not inherently dangerous, it just needs to be managed. Just like we did with jet fuel.

But all it proves is that battery tech ain't there yet, which anyone with half a brain knew already.

“The cabin of the plane was obstructed by two tons of lithium-ion batteries and cooling equipment, with little room for passengers. It certainly wasn’t a cabin setup that would make any sense commercially,”

Especially since that has already been done in 2019: [1]harbour-air-and-magnix-announce-successful-flight-of-worlds-first-commercial-electric-airplane

[1] https://www.harbourair.com/harbour-air-and-magnix-announce-successful-flight-of-worlds-first-commercial-electric-airplane/

Yup.. Little room for passengers, luggage, and a challenge common to traditional aviation. Like landing. Landing weight is usually lower than take-off weight because aircraft get lighter as they fly. Or have to dump fuel to get to a safe landing weight & land. That doesn't happen in e-aviation so landing gear would need to be reinforced to cope with landing 2 tons of empty batteries.. And those carry their own hazards-

https://www.nature.com/articles/s41598-017-09784-z

This paper presents quantitative measurements of heat release and fluoride gas emissions during battery fires for seven different types of commercial lithium-ion batteries.

Interesting paper. I'd seen reports of the risk of HF during battery fires, and wondered where the the F came from.

Large passenger planes often have maximum landing weight restrictions that are lower than the allowed take-off weight - but single engined aircraft don't (in case of engine failure on takeoff). Actually the difference in between take off and landing weight allowances tends to be most significant (unsurprisingly) for larger long range aircraft. By the time you are in 2 engine commuter style turboprops there is often little difference.

The problem is that they haven't redesigned the plane to make it much lighter.

Aren't they already using an electric plane between 2 islands in the Orkneys, where the flight is only 5 minutes long?

I would imagine they had to redesign the plan a little to allow it to carry all that battery weight.

I also imagine that there wasn't much weight to remove in the first place - this wasn't some Chelsea Tractor at the beginning.

The obvious solution is to make the plane out of styrofoam.

Was disappointed that they aren't using LiPo batteries...

It's not running but the researchers did manage to bag £9m worth of government funding.

https://www.pressandjournal.co.uk/fp/news/islands/1893676/electric-plane-plan-for-islands-receives-uk-government-cash/

Should be more than enough beer money for a couple of years by which point the idea will be scrapped on feasibility grounds!

Yuneec (which at the time was 50% British owned) developed the E430 Commercial 2 seater aircraft eleven years ago. It won various awards but was sadly not developed further.

https://en.wikipedia.org/wiki/Yuneec_International_E430

If you really want to, you can go out today and buy a Pipistrel Alpha Electric.

https://en.wikipedia.org/wiki/Pipistrel_Alpha_Trainer

Tradeoffs: it has a very limited endurance, and a limited payload.

I'm in no way shape or form an aeronautical engineer -- which should make all of you feel a bit safer. But if I take the empty weight of a Cessna Caravan (2145kg), subtract maybe 200kg for replacing the normal turboprop with an electric motor, add 2 tons of batteries (1814kg), I get a takeoff weight of 3759kg with no cargo, no passengers, and no pilot. Subtract that from the maximum takeoff weight of 3969kg and the payload would be 210kg. Enough for a pilot, a parachute (I suspect any sane test pilot for this thing would want at least one),a sixpack of beer, and a not overly large dog.

I wonder if someone who knows what they are doing could check the numbers.

Just as the article stated:

"Although it is a big step in research 'n' development terms, it is not quite a commercial thing just yet: "The cabin of the plane was obstructed by two tons of lithium-ion batteries and cooling equipment, with little room for passengers. It certainly wasn't a cabin setup that would make any sense commercially," reported the newspaper.

I think it would be neat to experience flying in an e-plane that has no (or very little) engine noise.

"I think it would be neat to experience flying in an e-plane that has no (or very little) engine noise."

Along with thousands of others, I've already experienced that - when I flew a glider. Wind noise takes over. My car (a hybrid) has no engine noise when pooling around town, either, though you then appreciate how much noise comes from types on tarmac...

A very high proportion of the noise made by anything with a propeller on it comes from the prop, specifically from the outer part of the blades and the tips, so using an electric motor to spin the prop may not make much difference to the noise level.

Thats why most glider tugs in the UK use smaller diameter four blade props: reducing the prop diameter gives a fairly large noise reduction because the tip speeds are a lot lower at the same RPM. There's a disadvantage too - the four blader is less efficient, partly because the aircraft cowling drag is relatively larger than it would be on a larger diameter two blade prop and partly because the more blades there are on a prop, the more interblade interference there is, but we put up with that for the sake of our neighbours.

If you really want to find out about silent flight, though, go here to find your nearest gliding club in the UK

https://www.gliding.co.uk/club-finder/

Other countries have similar sites. Visit your nearest club, see what its all about and, if you like what you see, take a trial flight. But, you'll have to wait until COVID-19 abates rather more and we can operate two-seat gliders again: 2m social separation in a glider cockpit - you'd have to be kidding!

Leave the dog behind and you get a small polypin of beer on board. I'm guessing that this wasn't 'hey look at my useful electric plane' but rather 'look at this cool drop in replacement for a turboprop. All aviation design is about compromise - and the Caravan was designed as an efficient load hauler, so good weight carrying capacity and space for your battery pack to show that your ideas work. If you wanted to make it useful you could redesign the wing etc. to gain payload - that might compromise performance in other ways, but maybe for a literal puddle jumper it would work economically. And as batteries get better (or fuel cells lighter or whatever) they will have a certified motor ready to go.

Just to save everyone time, can we take the usual El Reg commentary as read?

1. It will never work.

2. We are about to run out of Lithium

3. It will take too long to recharge

4. The batteries are too heavy and the plane will never fly

5. I personally only ever need to fly to New Zealand non stop with an entourage of 500 people and my race horses.

6. It will catch fire and explode

7. Heathrow only has 3 spare 13 amp plug sockets

Have I missed anything?

8 - Don't forget the children.

8. The captain will find that WH Smith's never have any spares in stock

9. It's a bugger to find that little ribbon to hook out the batteries

Maybe El-Reg readers are on average a bit more proficient in physics ?:

https://upload.wikimedia.org/wikipedia/commons/c/c6/Energy_density.svg

A Lithium-Ion battery has 0.25 MJ/Kg. kerosene has 44 MJ/Kg.

Kerosene has a weight to energy ratio outperforming L-ION by a factor of 176.

Since there is a 1:1 relation between weight of planes and their energy use, it is hard to imagine that electric planes will be an efficient solution given the current state of battery technology.

Extrapolate the Cessna to a 747-8, having an empty weight of 221T, this is 70 Cessna's, which would require 140 ton of L-Ion batteries to take off.

> A Lithium-Ion battery has 0.25 MJ/Kg. kerosene has 44 MJ/Kg.

It's not quite that simple; converting electricity to motion is more efficient than converting fuel to movement - about 80% vs 40% for a jet engine, from yet more poking around the interwebs.

The rule of thumb I saw in a few places indicates a weight ratio of 20:1 is reasonable for batteries vs fuel, so I took that and ran with it ;)

and hopefully some of them remember that a heat engine is at best about 30% efficient in turning fuel into work, and an electric motor can maybe hit 90%, so actually your factor is 59.And you decided to use Li-Ion batteries - let's use Li-Air batteries that achieve 6MJ/kg. So with that 30% to 90% efficiency your kerosene is about 2 times more energy dense. OK, you win by chucking your fuel out the back - but it's not nearly as clear cut as it is often made out by the '640K ought to be enough for anybody." brigade.

> 4. The batteries are too heavy and the plane will never fly

Ooo. *rubs hands*

At a glance on t'interwebs, it looks like the rule of thumb is about 20:1 for battery weight vs airplane fuel weight. And a 747 uses about 70[*] tons when flying from London to New York. Which means it'd need 1400 tons of batteries to be able to do the same journey.

Or a mere 700 tons, if we believe the claim in the article that they're going to halve size and weight for their batteries while still (presumably) maintaining the same capacity.

Either way, take-off is going to be fun ;)

I'm sure there's some very clever people beavering away to address issues like this, but at the current rate of battery improvements (5-8% per year), it's going to take a long time to reach even just a tenfold improvement.

(about 40 years, assuming an average of 6% annual compound growth...)

And that brings us nicely to...

> 3. It will take too long to recharge

Working on the basis that Tesla's supercharger can charge 600kg of batteries in about an hour, that 700 tons of batteries would take about 1100 hours. Or about 45 days.

Admittedly, Tesla is working on a Megacharger[**] for their trucks, which looks like it'll push about six times the charge out. But that'd still take about nine days, and it'll be pushing about a megawatt of power out for nine days solid, which brings it's own engineering and safety challenges.

Still, I'm again sure there's some bright people looking into this, too!

But overall, I think I'm going to hold out for Doc Brown's Mr Fusion. After all, cold fusion is still only twenty years away ;)

[*] Dunno how much of a difference it makes moving to shorter hops; it's not clear from t'interwebs if the 70 tons includes the fuel cost of getting airborne and landing

[**] Does make me wonder what the next iteration will be called, seeing as how Uber is already taken...)

You can play the sums in all sorts of ways. I think the first commercial electric planes will probably be aimed at the 500 km inter-city routes. Power consumption in cruise flight for a small turboprop might be as low as 1000/2000 kw/hour, so doing the sums in Teslas - thats 10 tesla battery packs per hour. So 5600 kgs for an hour of flight in cruise. Couple of super capacitors to get you off the ground and you are approaching London to Paris.

I was rather hoping to hear what it sounds like, rather than that dreadful soundtrack.

The El Reg story is missing something - this is not the first flight test of the Magnix engine in a commercial airplane - that was in December, in Vancouver, Canada, with Harbour Air testing it in one of their DeHavilland Beaver float planes. There is a video of the first flight (with sound) from a wing-mounted camera in this article: https://www.flightglobal.com/aerospace/harbour-air-to-resume-electric-powered-beaver-flights-as-certification-work-begins/136071.article

Harbour Air is a local airline serving the BC south coast with float planes making mostly short hops between city harbours, which makes them a good candidate for electric motors with relatively short battery life. They operate a variety of float planes including the Beaver and Cessna Caravans. The float planes have a reputation for making quite a racket on take-off from the harbour, so anything to reduce the noise would be welcome.

If it's take-off noise, what about a hybrid? Enough battery capacity to get you in the air then fire-up a normal engine to power the rest of the flight and recharge the batteries.

How about an enormous elastic band?

You mean like this?

http://sustainableskies.org/a-chance-to-unwind/

It would be nice to know how many hamsters in wheels would he needed to do a similar job.

After all, I think they could be classed as a renewable resource.

Will probably have to exchange batteries at the destination