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Vigilant1

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Check out the Archer Aviation Investor Presentation Feb 10th 2021 (PDF Download).
50 pages of really interesting projections.
Some serious money backing eAviation here:

Just my opinion, but something smells bad about this. There's oodles of cash now, in general, looking for investments (the proliferation of these "blank check SPACs is Exhibit A). Crazy ideas are getting funds sight unseen. Now, Archer investors, the early ones, have made money on spec based on this announced UAL purchase that makes zero economic sense (+1 to Dan Thomas). United might change their mind tomorrow with no impact to them, depending on the terms of the offer. I hope the SEC is taking a good look at this. I am NOT saying securitiy manipulation is going on, only that this is what it might look like.
 

EzyBuildWing

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....the original discussion has not survived, but an explanation has; it attributes a very similar quote to the Cambridge mathematician Professor Douglas Hartree, around 1951:

I went to see Professor Douglas Hartree, who had built the first differential analyzers in England and had more experience in using these very specialized computers than anyone else. He told me that, in his opinion, all the calculations that would ever be needed in this country could be done on the three digital computers which were then being built—one in Cambridge, one in Teddington, and one in Manchester. No one else, he said, would ever need machines of their own, or would be able to afford to buy them.
Maybe the sky's will soon turn black with Archer Aviation's "e-Plane" ?
 

Sockmonkey

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....the original discussion has not survived, but an explanation has; it attributes a very similar quote to the Cambridge mathematician Professor Douglas Hartree, around 1951:



Maybe the sky's will soon turn black with Archer Aviation's "e-Plane" ?
That was based on the the capabilities and needs of people at the time he said it.
Battery tech is still the stumbling block for electrics. The second we double the energy density of batteries is the second all the electric vehicle ideas will start getting used.
It was the same thing with the airplane itself. The second that gasoline engines had a good enough power-to-weight ratio, planes were getting used everywhere.

Electrics are a little funny in this way because all the concept and design engineering work has been done beforehand, and they're all just waiting for the better batteries to show up.
 

John.Roo

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....
Electrics are a little funny in this way because all the concept and design engineering work has been done beforehand, and they're all just waiting for the better batteries to show up.

I posted this in e-soaring thread, but maybe interesting also here....

Many pilots are complaining about short range of actual electric airplanes. And because net of superchargers on the airports is not existing they beleive that electric airplanes are OK for training and maybe short "jumps" between two airpots with charging infrastructure.

It is also interesting that everybody is watching info about new battery cells, but charging is in "shadow".

Well... chargers are important and I even more important is development of light charger able to be aboard of electric airplane. I have info that there is available 12 kW charger working with 220 V and 400 V / 16 Amps and also 400 V and 32 Amps. This charger weight is only 15 kg so can be easily aboard of electric airplane. Well this is really exciting for me!

So what electric airplane needs to make long flight? Only electric socket available at the airport.
If is 220 V it will take very long time, but OK, still possible to re-charge. But if is available 400 V socket than you can re-charge with speed of 1 hour charge = 1 hour of flight. OK OK... still not fast like refueling, but this will give you freedom to fly everywhere where is electricity available.

Using data from our Phoenix....
With 20 kWh battery you can fly approx. 180 km (still with safety reserve). But lets calculate with 150 km distance at 150 km/h speed.
+-One hour.
You have charger on board so no need of "ground team with car transporting heavy charger" or "net of superchargers". Just plug cable, start charging and in a bit over one hour (coffee and discussion with friends) you continue to another airport. Easily you can make 600 km a day (3x stop) or even more.
Do you want to make soaring? Do it :) TakeOff to 600 m and try to catch some lifts. Not succesfull? TakeOff again.... Do you want to "fly arround chimney" for fun (sighseeing flight in home airport area) - do it :)

Energy for one hour will costs you approx. 2 EUR.
Cost for complete propulsion with 20 kWh battery will cost you about the same like new Rotax 915i - only you have "fuel practically included" in price of propulsion. Keeping some reserve in battery (no discharge to 0%) and using plane like "motorglider" will keep you battery in good condition for really long time.

Don´t waste time waiting for "super high end battery cells". You can enjoy "e-flying" already :)
 

John.Roo

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Battery-tech for Aviation....where we are right now:

Where we are right now?
That is simple :cool:
As far I know Pipistrel has highest numbers of produced electric airplanes. And they use typical cylindrical Li-Ion cells 18650 with 3,7 V nominal voltage.
So right now are electric propulsion producers using mostly 18650 cells and you can also see projects using 21700 cells. Why? Because they are affordable and characteristics are perfectly known. I am sure they will come new systems with higher power density, but first somebody must test theese cells in real life conditions (not only laboratory tests on few samples). And also some company must start mass production, otherwise will be price too high.
 
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Dan Thomas

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Some months ago we had this discussion. Someone said that we skeptical guys are like the guys that said the motorcar would never replace the horse and buggy. In return, I pointed out that the first motorcars appeared in the 1880s or 1890s, and horses and wagons were still being used in some rural areas in the 1940s, 50 years later. Why? Because there were no service stations in much of the country. It costs money to build and operate a gas/service station, and to recover those costs you need the traffic, and to get the traffic you need the highways. So until the market was able to support more service stations, a lot of folks still had to rely on animals for transportation. In fact, I remember a couple of old farmers that still used horses and wagons around our part of town in the 1960s.

Now, we have a parallel to that in the electric aircraft, except that instead of needing more highways and service stations, we need more airports and charging stations, or at least a 220V electrical outlet. More airports aren't happening; too many are being closed and sold off for housing or commercial developments. And 220V outlets with significant current capacity? Who is going to spend money on those in case an electric airplane shows up once or twice a year? And the installers and operators of such outlets aren't going to give the power away, either. They'll want more than the price of the power to pay for the installation and maintenance of it.

So the early owners of electric airplanes will be faced with the same problems the owners of Model Ts did in 1915. Where do I get gas for this thing? Most had to carry several cans of gas for long trips through territory that had no services. Pretty hard to carry a bunch of extra batteries for a long cross-country in your electric airplane.

It's a big problem. And wishful thinking won't make it go away. With current battery technology the ranges will be very short, so without places to recharge (and the extra time to wait for charging), you won't see too many people laying out $150K (or a lot more) for a little electric airplane.

Gasoline and diesel still pack 60 times the punch of lithium batteries. Even with the 25 to 30% efficiency of the ICE engine, that fossil fuel is still 15 or 20 times more powerful. We need a battery improvement an order of magnitude better, not just double.
 

John.Roo

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Hello Dan!
Sorry - because I am flying in Europe I am not considering situation in US. In EU is 220 V really everywhere. And when I was plannig e-flight across Germany I found out that every aeroclub airfield has also 400 V socket. Only a very few small UL airfields are without electricity.
I agree that nobody will invest in new infrastructure for 2-3 arriving electric airplanes / year. Therefore I try to use what is already existing and beleive me - in EU is situation really good.
Yes, capacity is limited so this solution is not for pilots requesting often long flights. That is reality.
Price... price is higher only because it is something new and only few producers are offering whole system. Price for 1 kWh in automotive industry is far below 1 000 EUR/ 1 kWh (typical price of battery pack for airplanes). In fact - would be great to achieve car industry prices...
Engines suitable for sport aviation are expensive. For price of Rotax 912 you have complete new car. For price of Rotax 915iS you can buy Tesla model 3 :) And than you still burn 10-15 lit of MOGAS / hour (in fact is more like 15-20 lit / hour with 915iS). And in EU we pay a bit over 1 EUR / lit of MOGAS and far over 2 EUR / lit of AVGAS.
I know it sounds crazy, but I expect that electric propulsion will be in short future "poor pilot option" :)
 
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Dan Thomas

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Price for 1 kWh in automotive industry is far below 1 000 EUR/ 1 kWh (typical price of battery pack for airplanes). In fact - would be great to achieve car industry prices...
Engines suitable for sport aviation are expensive. For price of Rotax 912 you have complete new car. For price of Rotax 915iS you can buy Tesla model 3 :) And than you still burn 10-15 lit of MOGAS / hour (in fact is more like 15-20 lit / hour with 915iS). And in EU we pay a bit over 1 EUR / lit of MOGAS and far over 2 EUR / lit of AVGAS.
I know it sounds crazy, but I expect that electric propulsion will be in short future "poor pilot option" :)
At US$100 per kW/h, the 21 kW battery pack in the electric Pipistrel is $21,000. I think a new Rotax 912 is no more than that. What is the life of that battery pack, in terms of hours flown?

That Pipistrel has a 60 kW/h motor in it. The 21 kW/h battery therefore will drive it for 20 minutes at full power. WE have a LONG way to go.
 

Vigilant1

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At US$100 per kW/h, the 21 kW battery pack in the electric Pipistrel is $21,000. I think a new Rotax 912 is no more than that. What is the life of that battery pack, in terms of hours flown?

That Pipistrel has a 60 kW/h motor in it. The 21 kW/h battery therefore will drive it for 20 minutes at full power. WE have a LONG way to go.
When last we looked at this, Pipistrel (who presumably knows more about the battery than anyone) says it is good for 300 to 700 cycles. Replacement batteries are over $21k, so that is $30 per hour right there if you baby it and get 700 cycles. Fuel for a Rotax 912 AND the reserve for a total replacement at TBO is less than that. The gas powered Pipistrel is cheaper even if electricity was free (it ain't). And, as a bonus, with the 912 you can actually go somewhere.

In the US, it is very hard to make an economic case for EV flight.
 

EzyBuildWing

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Vid below "sells instant-sizzle" ....
Hey, what/where can I buy equivalent "aviation sizzle" that repeatedly brings instant smiles/laughter/euphoria to myself and one passenger?
Maybe a Lockwood Aircam with twin 150HP Emrax pushers, and just enough batteries to do a few circuits after it silently leaps off the ground in about 3' and climbs near vertically to say 500 feet.( Ludicrous Mode)!
Anyone got any ideas?

 

Vigilant1

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Vid below "sells instant-sizzle" ....
Hey, what/where can I buy equivalent "aviation sizzle" that repeatedly brings instant smiles/laughter/euphoria to myself and one passenger?
Anyone got any ideas?
A catapult? Like flying off the USS Nimitz, but in your own airplane and your own field. Make it steam for extra cool points, or go low-tech with a tower and a heavy falling mass. Electric motor to spin up a flywheel? Keeping all the energy storage stuff on the ground reduces costs, enables even higher acceleration, and lets you have a plane that can be fairly practical for normal flying. Of course, it does limit where the giggles will occur.
RATO/JATO bottles?
 

Dan Thomas

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=NOISE problem,
fly comfort,vibrationes...
dB/ $ =???
Yes, electric motors are quiet. Propellers are definitely not quiet, and the electric airplane will still have a propeller. For many light airplanes, the prop generates as much noise and vibration as the engines does, and sometimes more. A tractor configuration means that the prop, every time a blade passes, sends a pulse of air against the windshield and cowling, and a lot of noise is transmitted to the cabin. Electric airplanes won't cure that. Once again, we are reminded that what we experience in cars does not carry over to aircraft.
 

Malovanyy

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The first thing you need to ask yourself is what the aim of the electric planes is? The obvious answer is greenhouse emissions reduction. The whole movement with electric planes just went from that statement and the good experience with electrification of cars and started to investigate how we can make it work in planes. The better approach is too look how we can most efficiently reduce the net worldwide emissions, not how we can electrify planes. We can of course remove 2/3 of seats in a b737 and fill it with batteries and there you go - you have a “full size” electric regional commuter. The net greenhouse emissions per person and km would be probably even higher than for an ordinary turboprop. The battery production causes also greenhouse emission and installing more batteries to be able to lift those batteries in the air is not really a solution. 1 kWh of batteries makes a largest reduction of emissions when the transport of that batteries can be done efficiently and when the degradation is low. Take a sea transport as an example. It uses the dirtiest fuel but operates 24/7. The sea transport is the most efficient way to carry “heavy stuff”.
For airplanes the real realistic way forward in near future is renewable chemical fuel, like biodiesel used in piston and turbine engines. Good emission reduction and no need to rebuild the infrastructure or wait for the batteries to improve.
 
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