Why battery-powered aircraft will never have significant range

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speedracer

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Feb 4, 2020
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Check your oil,Smell your oil,look at your oil,
and if you dont like how it looks or smells,then
plan to change your oil when its hot so it all
comes out of your levely parked car/truck,plane, and put in good oil and a good
filter.
Realy important with anything with lots of miles or time on it.
Motors are not cheap,good oil is.
And of course you can ask me how I know.
Changing oil: A guy donated his 2,000 Corvette (I have a 1999 with 60 K miles on it) to the Corvette Museum in Bowling Green Kentucky. It has 773,388 miles on it and has never had a major repair. (Google knows all about it.)
 

Aesquire

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Today, if you can feel the dirt in the oil, repairs are in your future. The use of engine oil as hydraulic fluid in the variable valve/cam system makes the olde ways obsolete.

Further, oil ratings are important for modern cars, some more than others. Real alphabet soup stuff.

And then there's the weird stuff. My motorcycle is utterly incompatible with Mobile One. The lubrication part is fine, but an additive dissolves the glue holding the magnets in the a!ternator. When they move, they get into the drive train & chaos ensues. More, the oil for many bikes has to be compatible with the wet clutch, and the wrong goo will result in zero movement and annoying repairs.

Cars with steel chains in the CVT have special needs too. Poor reading skills can lead to a pile of steel plates trying to circulate inside a casting not meant to contain hardened steel blades in motion.

Electric motors are going to have unique requirements, just as some turbines and diesels do. Likely it will be a small amount of ozone resistant or glue/insulation/fairy dust friendly alchemical brew.
 

dog

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Messages
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Today, if you can feel the dirt in the oil, repairs are in your future. The use of engine oil as hydraulic fluid in the variable valve/cam system makes the olde ways obsolete.

Further, oil ratings are important for modern cars, some more than others. Real alphabet soup stuff.

And then there's the weird stuff. My motorcycle is utterly incompatible with Mobile One. The lubrication part is fine, but an additive dissolves the glue holding the magnets in the a!ternator. When they move, they get into the drive train & chaos ensues. More, the oil for many bikes has to be compatible with the wet clutch, and the wrong goo will result in zero movement and annoying repairs.

Cars with steel chains in the CVT have special needs too. Poor reading skills can lead to a pile of steel plates trying to circulate inside a casting not meant to contain hardened steel blades in motion.

Electric motors are going to have unique requirements, just as some turbines and diesels do. Likely it will be a small amount of ozone resistant or glue/insulation/fairy dust friendly alchemical brew.
Na,electric motors use sealed bearings,and the ones that are liquid cooled will be hermeticaly sealed.There is one new factor for the bearings
and that is "gyroscopic loads" or that what I am
calling it,that would not be present in most previous electric motors,but that is probably a
small additional load rating that might vanish in the prop loads.Ozone is I think only a consideration with brushed motors and I cant
see useing brushed motors for a plane,but what I know about electric aircraft motors and
$7 would buy me I a fancy coffee drink,or at least it would buy someone else a fancy coffe drink.
 

Dusan

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Na,electric motors use sealed bearings,and the ones that are liquid cooled will be hermeticaly sealed.There is one new factor for the bearings
and that is "gyroscopic loads" or that what I am
calling it,that would not be present in most previous electric motors,but that is probably a
small additional load rating that might vanish in the prop loads.Ozone is I think only a consideration with brushed motors and I cant
see useing brushed motors for a plane,but what I know about electric aircraft motors and
$7 would buy me I a fancy coffee drink,or at least it would buy someone else a fancy coffe drink.
If the electric motor needs gearing, it might have stuff like silicone nitride bearings and weird oils. A very informative video for the tesla motor and gears here:
 

Saville

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Boston Ma
Joby Aviation's latest vid.... technology seems to cover all bases.....! Great pitch!
Any doubters out there?


Yes.

For example, around 6:46 he says it was designed with "fast charge" capability to enable recharge while pax are unloading and then loading.

That's a very loose definition. What's the time between unload and load? Why didn't he simply say "We can fully recharge the batteries in XYZ minutes."?

What kind of voltage/current do you need for the kind of recharge speed he's implying (say 20 minutes)?

"Reward us with incredible cycle life"... what are the numbers?

"In the lab we have demonstrated more than 10,000 flight cycles..."

What were the parameters of those tests?

It's all a lot of talk. Talk we've been hearing for decades. We heard similar talk about the flight rate of the space shuttle. Didn't pan out in actual service

It's actual service that matters.

WHEN his aircraft starts his taxi service and

WHEN I get actual performance data not lab simulations of flight cycles...and

WHEN I see the actual operating costs, recharge times, battery life etc.

...then I will know if it's a crock or real.
 
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dog

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Messages
578
Yes.

Fro example, around 6:46 he says it was designed with "fast charge" capability to enable recharge while pax are unloading and then loading.

That's a very loose definition. What's the time between unload and load? Why didn't he simply say "We can fully recharge the batteries in XYZ minutes."?

What kind of voltage/current do you need for the kind of recharge speed he's implying (say 20 minutes)?

"Reward us with incredible cycle life"... what are the numbers?

"In the lab we have demonstrated more than 10,000 flight cycles..."

What were the parameters of those tests?

It's all a lot of talk. Talk we've been hearing for decades. We heard similar talk about the flight rate of the space shuttle. Didn't pan out in actual service

It's actual service that matters.

WHEN his aircraft starts his taxi service and

WHEN I get actual performance data not lab simulations of flight cycles...and

WHEN I see the actual operating costs, recharge times, battery life etc.

...then I will know if it's a crock or real.
Crock or not in this or any specific case isnt
going to deter the main players who do not and
will not own or operate aircraft in the eVTOL
taxi buisiness.
They own flat roofed real estate in the center of
citys worldwide and the taxi booking companys that operate again in city centers worldwide.
The market is there,the buisness model of
useing a phone app to travel anywhere at anytime is working worldwide will instantly accomadate eVTOL taxis.
The company that has the numerous little ducted fans on the wings of a canard has actualy got an advantage in that the design is
both quiet and you can stick your face in the motor and still have a face,and or a little oopsie
is not going to result in carbon shrapnel.
So yup,the bar is set high,but the tech pieces are all here now for some kind of viable eVTOL
taxi in the under 200 mile range.
Other major hurdle will be getting these things
certified to fly out of high density urban settings.
That pretty much cooks the whole idea,right?
As idiots will shoot at them,and so they will have to be litteraly bulletproof,at least on the
bottom.
 

EzyBuildWing

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Sydney NSW Australia
Joby Aviation eVTOL .....6 tilting propellers, and each propeller has 2 motors and 2 controllers and two batteries.
Excellent redundancy!
Why not install such a prop-motor-battery combo into say a Pipestrel motor-glider?
 

John.Roo

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Letohrad / Czech Republic
Joby Aviation eVTOL .....6 tilting propellers, and each propeller has 2 motors and 2 controllers and two batteries.
Excellent redundancy!
Why not install such a prop-motor-battery combo into say a Pipestrel motor-glider?
It is about the weight....

However for example....
During flight in Pipistrel Velis you can disconnect one battery pack and finish flight with only one battery pack. It is not possible to takeoff, but it gives enough power to keep level flight.

And for example Joachim Geiger motors are "duplex" so you have two controllers for one 60 kW (40 kW continuous) power. In simple words - they are "two independent motors on one shaft".

They are ways how to increase safety of aviation electric propulsion systems, but is also never ending fight with weight....
 

Dan Thomas

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Sep 17, 2008
Messages
6,168
It is about the weight....

They are ways how to increase safety of aviation electric propulsion systems, but is also never ending fight with weight....
Yup. That fight is bad enough with an ICE, and a builder is often his own worst enemy, want to add so many goodies and/or use cheaper, heavier materials. Going electric offers so many more ways to make a good taxi trainer...
 

Victor Bravo

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KWHP, Los Angeles CA, USA
Forgive the repetition, I know I've posted this before, but it bears repeating. Me and a lot of other folks here were eyewitnesses to the "electric revolution" in R/C models. When the first electrics came out they were a joke. Now they are dominant by far. Yes of course it is not a direct comparison to full size aircraft, you can't just draw a straight line scaling up from one to the other. I realize that wing loadings, drag, weight, and power loadings are not the same proportion.

But the basic principle of electric power systems getting better and better every year is real in my mind. My own 'witness to history' experience shows me that what we used to scoff at finally became the norm. So I can't scoff at the idea that one day most of us will be flying electric airplanes with the same power, range, duration, and speed as gasoline (or glow fuel :) ).

What I can and do scoff at is the people saying that day is today or tomorrow.

Today and tomorrow we can have a small efficient little E- air scooter that is or looks a lot like a glider, and can fly for a modest amount of time/distance. All that stuff is there for retail purchase right now, which is a mind-blower for most of us.
 
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dog

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Messages
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Forgive the repetition, I know I've posted this before, but it bears repeating. Me and a lot of other folks here were eyewitnesses to the "electric revolution" in R/C models. When the first electrics came out they were a joke. Now they are dominant by far. Yes of course it is not a direct comparison to full size aircraft, you can't just draw a straight line scaling up from one to the other. I realize that wing loadings, drag, weight, and power loadings are not the same proportion.

But the basic principle of electric power systems getting better and better every year is real in my mind. My own 'witness to history' experience shows me that what we used to scoff at finally became the norm. So I can't scoff at the idea that one day most of us will be flying electric airplanes with the same power, range, duration, and speed as gasoline (or glow fuel :) ).

What I can and do scoff at is the people saying that day is today or tomorrow.

Today and tomorrow we can have a small efficient little E- air scooter that is or looks a lot like like a glider, and can fly for a modest amount of time/distance. All that stuff is there for retail purchase right now, which is a mind-blower for most of us.
Well then,Ill see your scoff and raise you a derision.
Thinking about the idea of energy storage ,from
a very basic perspective ,an ICE could be viewed as a battery based system.
Lets see if I can describe that,in a chemical battery ,ions are transported with there charge
and chemicaly converted giving up electrons in a reversable reaction,often this reaction is noticably exothermic.
In a liquid fuel ICE a chemicl reaction occurs,with ions forming new compounds in
a highly exothermic reaction,that is also reversable.That process as we know is iether
very energy intensive,or leaving it to natural processes takes mega years.Niether of which
will look good on a plane.
So you have unfortunately been arguing that a battery is better than a battery.
Every major manufacturer of traditional ICE is now looking at elcectric and hydrogen alternatives,with vast investments in infrastructure,research and development,and just outright banning new carbon emmisions.
Rethink my friends,especialy if you have younger friends and family in aviation and other energy intensive industries.
 

Saville

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Boston Ma
Part of the reason why there is skepticism is the way possibilities are presented...like "Game Over!"

We know the game isn't over so when someone says that, the bs-o-meter gets pegged.

Here is another example. I just stumbled across this YT video whose title is:

"SynRM | A new giant in the electrical world"

Giant? Makes it sound like a massive breakthrough. Already the BS-o-meter is quivering off the peg.

Until you read the comments and see some things the video failed to mention. This is from one commenter [emphasis mine]:

"Nice video, but as an electric motor developer I have to clear some points up, that are just not true.

While the efficiency is really high, the torque output is definitely not.For the high efficiency induction motors, you might be able to replace them with syncRel motors of the same size. But if you look at through-ventiled induction motors, you will not be able to match their torque with a syncRel motor of the same dimensions.
..........
No, syncRel motors have not started replacing induction motors in most industries. That is just not true and I'd like to know where you got statement from.
..........
Also here are some disadvantages of syncRel motors: SyncRel motors rely on small airgaps between rotor and stator. The rotor design is inherantly less stable than that of an induction motor. Therefore it is a terrible choice for high speed applications.
.........
Another factor often overlooked is the terrible overload performance.
Induction motors on the other hand can just run nominally at 400V and still have lots of overload capabilities. This is also why you should not use pure syncRel motors for traction or electric vehicle applications. In these applications you want very high overload capabilities.
......
Yes, Tesla uses IPM-synchRel motors. But what everyone always fails to understand is the reason behind this. At low speeds, more than 90% of the torque is due to the magnets. Only if the motor is running at high speeds, the reluctance torque becomes relevant. Looking at the design I would estimate that maybe 50 % of the torque at max rpm might come from reluctance. So what Tesla is basically doing is taking a PM motor and adding a bit of reluctance torque for better field weakening performance at high speeds."


Hyperbole just makes for lots of eye rolling and weakens support for the thing being hyped.
 

Aesquire

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Well then,Ill see your scoff and raise you a derision.
Do you really want a list of how your analogy is wrong, violates the laws of physics, and is silly? Or is it just arguing to win regardless of the facts?

I don't really care, just mildly curious. Not interested in arguing religion.

Dusan! Thanks for the Tesla video, the need for exotic oils was mere speculation on my part, and what I've been seeing in the IC world. Direct injection, and very variable valve control promise getting much closer than today to the theoretical limits. I'm amazed at what Toyota and Dodge and VW are doing to reduce emissions below the already really darn clean levels, and getting more miles out of each liter of fuel.

I speculate that it might even be better for the environment to review the regulations on pollution. Both bureaucratic inertia and modern technology might mean that ( speculative example ) accepting a few more ppm of CO would gain enough improved mileage to make it a better choice. Instead of PPM ( easier to measure directly ) Grams per passenger mile?

Insert here meme picture of electric car being recharged at side of road by diesel trailer generator towed by roadside assistance minivan.

So there may be a market for the Recharging Plane that carries a generator set and flies from airfield to airfield to recharge electric aviation without spending for infrastructure improvements, and of course, a Bush version to land on sandbars etc. to take care of the country folk. Murphy Mega Moose?
 
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Victor Bravo

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Part of the reason why there is skepticism is the way possibilities are presented...like "Game Over!"

We know the game isn't over so when someone says that, the bs-o-meter gets pegged.

Giant? Makes it sound like a massive breakthrough. Already the BS-o-meter is quivering off the peg.

Hyperbole just makes for lots of eye rolling and weakens support for the thing being hyped.
Oh for goodness sakes Saville, shushhhh ! You're letting the entire vaporware world know how we older folk quickly separate BS from reality, and if the Millennials figure out how our BS filter works they might change their tactics and be harder to spot.
 

Saville

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Oh for goodness sakes Saville, shushhhh ! You're letting the entire vaporware world know how we older folk quickly separate BS from reality, and if the Millennials figure out how our BS filter works they might change their tactics and be harder to spot.

Terribly sorry ;)
 

Dusan

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Canada
Joby Aviation eVTOL .....6 tilting propellers, and each propeller has 2 motors and 2 controllers and two batteries.
Excellent redundancy!
Why not install such a prop-motor-battery combo into say a Pipestrel motor-glider?
Multiple propellers as redundant for winged flight are not making much sense. If you replace one prop with 4 - having the same disk and blade area, the cords are halved, and so are the Re numbers, assuming same blade speeds. At small propeller size - as the Pipistrel - this have a pretty large impact on prop efficiency.
 
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