Waterbomber
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Re: Electric planes: the state of the art

Thu Dec 27, 2018 9:08 am

RJMAZ wrote:
Waterbomber wrote:
The proposed windmill charging is not very efficient because windmilling brings a lot of drag. It would be much more interesting to charge through a mecanically linked generator.

As I said, there is little merit to the simple hybrid idea. There are ways that hybrid could work in a limited way and in theory but IMHO we're talking about complex combinations and interactions.

Actually one of the most simple hybrid systems would be to have a turbofan engine and place the electric motor on the same shaft just behind the fan.

The electric motor could then double the speed and thrust of the fan during takeoff. The electric motor can then freespin during cruise running entirely off the gas turbine.

The electric motor can then turn into a generator during descent abd there us your mechanically linked generator. So the gas turbine will be at full throttle during descent but most of the energy is being sucked out by the generator. The electric motor/generator can also provide engine starting and power generation so you wont need an APU.

Such a design would still be 80% fossil fuel 20% electric like a Prius. As cool as this design sounds it won't please the environmentalists.

I much prefer the BMW i3 style hybrid as it is 80% electric and 20% fossil fuel. It has a little 25kw generator with a 9 litre fuel tank to top up the battery with 125kw of electric engine power. That tiny 25kw generator allows the i3 to more than double its electric range. If you are doing only short trips in the i3 the petrol generator does not have to turn on.

Using the the i3 style hybrid in an aircraft would work very well. If the flight was only 500kms long they could do it fully electric. If the flight is 1000kms long the generator has to run for the entire flight. This generator would also provide the emergency reserve fuel. For instance if there is bad weather at the destination airport as soon as they get the call mid flight the generator would then get turned on to start extending range. The generator could be sized to provide 50% of the electrical power required at cruising altitude.

These small 50 seat electric prototype aircraft they could simply install a 787 electric APU in the tail. That provides 450kw of electricity and would top up the batteries nicely.


Except that the i3 is an electric car with an optional range extender.
As already discussed, any amount of aircraft can't take off with a battery pack as main source of energy.
The above hybrid with the gas turbine as main energy supply is a challenge as it is to justify.
The ATR72 has 3600kW of total engine output, of which it uses about 75% at cruise. With a range extender APU with 450kW of output you won't get far.
 
leghorn
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Re: Electric planes: the state of the art

Thu Dec 27, 2018 9:56 am

Bmw i3 range extender has been discontinued.
 
RJMAZ
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Re: Electric planes: the state of the art

Thu Dec 27, 2018 9:57 am

Waterbomber wrote:
Except that the i3 is an electric car with an optional range extender.
As already discussed, any amount of aircraft can't take off with a battery pack as main source of energy.
The above hybrid with the gas turbine as main energy supply is a challenge as it is to justify.
The ATR72 has 3600kW of total engine output, of which it uses about 75% at cruise. With a range extender APU with 450kW of output you won't get far.

75% at cruise? That is 2700kw, where do you keep plucking these high power figures from? Cruise shaft horsepower is actually around 50% for a turboprop.

The ATR 72 with 70 passengers at 95kg can fly 850nm or 1574km. That is a takeoff fuel load of 2850kg. Minus landing fuel it consumes just under 5000lb of fuel on the trip.

A modern turboprop burns roughly 0.5lb of fuel for every shalf horsepower per hour.

The ATR cruises at 510km/h so that 850nm journey takes roughly 3.25 hours. 5000lb of fuel divided by 3.25 is 1500lb of fuel per hour. That means 3000hp average for the entire flight.

This figure doesnt take into account the much higher power and greater fuel consumption during climb. The 30 minute climb at full power represents 16% of the flight duration but burns 25% of the trip fuel. That means the ATR burns well below 3000hp on cruise. Definitely under 1800kw or 50% of maximum power.

I mentioned a 50 seat turboprop which is the ATR 42 in size. So a 787 sized APU acting as a 450kw range extender will probably add 40% range.
 
leghorn
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Re: Electric planes: the state of the art

Thu Dec 27, 2018 10:03 am

Show me an ATR in Europe that is flying anywhere close to 850nm. They are jumping across the Irish sea or Channel.
 
RJMAZ
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Re: Electric planes: the state of the art

Thu Dec 27, 2018 10:27 am

leghorn wrote:
Show me an ATR in Europe that is flying anywhere close to 850nm. They are jumping across the Irish sea or Channel.

Why would I have to show you that? This was done soley to calculate the very low power used during cruise.

If ATR's are being flown on 200-400nm flights then an electric aircraft can easily fly that far with current tech.
 
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SheikhDjibouti
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Re: Electric planes: the state of the art

Thu Dec 27, 2018 10:35 am

kalvado wrote:
SheikhDjibouti wrote:
I have to say that I'm losing patience with you; it would appear you are trolling.!

A lot of duckspeak, no solid numbers in terms of $$/flight or lb fuel/flight.
Relax, take a deep breath, and try to prove your idea actually worth bytes wasted.
I disagree about the duckspeak, but I'll take your advice and try to chill out & relax.
I also come from a financial background (what is they say about accountants; "they know the price of everything, and the value of nothing"), but as far as I am concerned this is not about the $$$. It's about doing the right thing.
(before the usual suspects chime in; yes, of course costs are a factor, and the end solution must be a reasonable one.)

When catalytic converters and unleaded petrol were introduced/legislated/made mandatory, it wasn't sold on $$$. Even now catalytic converters add cost to a basic vehicle, and back then the original ones were horrendously expensive. Plus between them and unleaded petrol, vehicle performance was reduced. Do you recall the days when you could buy a Porsche or an Audi either with or without an optional catalytic converter? The latter option were 10-15 mph slower, and $3,000 more expensive. Not surprisingly many people argued against such a crazy idea at the time. And now here we are arguing over electric power for aircraft. Plus ça change, plus c'est la même chose. :roll:

Thankfully for the car industry, since then the technology has improved, performance has caught up (and some...), and the costs have dropped.

So, please forgive me if I am prepared to accept a reduction in absolute aircraft performance, and a marginal increase in airframe cost, in an attempt to mitigate the use of fossil fuels.
Nothing to see here; move along please.
 
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SheikhDjibouti
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Re: Electric planes: the state of the art

Thu Dec 27, 2018 10:55 am

Waterbomber wrote:
I visualise what you are saying but I don't see the yield that you see. However, your Q400 is going to be more expensive to build and maintain because of the added systems.
Toyota has sold the world on the hybrid concept. They take a regular car, add regenerative braking, a battery pack and AC motors and sell it at a higher price based on the better fuel efficiency.
However, the math doesn't add up. The difference in fuel efficiency is insufficient to depreciate the price mark-up over a regular car. By the time that the price difference is earned back, the car would need a new battery pack.
So supposing that the proposed hybrid system does achieve an efficiency gain of say 10% including the added weight, this is likely to be exceeded by the cost of adding the hybrid system to the aircraft.

I'm reading
... don't see the yield
....more expensive
....sell at a higher price
....insufficient to depreciate the price mark-up
....cost of adding the hybrid system

I've already said it to one person; I'll say it again.

It's not about the cost; it's about doing the right thing.

If you're not old enough to remember when leaded petrol was the norm, and catalytic converters were an expensive (and generally unpopular) option, then please read my other post. For some of us, this is just déjà vu all over again.

Waterbomber wrote:
There could be an overall increase in efficiency because a smaller engine is going to run more efficiently at higher power settings.

Thankyou; that is all that I am looking for. :bigthumbsup:
And if we can keep the additional costs down to a reasonable level, that would be most excellent. :white:
Nothing to see here; move along please.
 
Waterbomber
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Re: Electric planes: the state of the art

Thu Dec 27, 2018 10:56 am

RJMAZ wrote:
leghorn wrote:
Show me an ATR in Europe that is flying anywhere close to 850nm. They are jumping across the Irish sea or Channel.

Why would I have to show you that? This was done soley to calculate the very low power used during cruise.

If ATR's are being flown on 200-400nm flights then an electric aircraft can easily fly that far with current tech.


No it can't. Remember that li-ion battery packs have only 2% the energy density of jet fuel.
Even if we consider electric motors to be twice as efficient as turboshafts, that would make it 4%. Good luck flying to anywhere with 4% the range of a regular ATR72, you won't even clear final reserve requirements, let alone total reserves.

Add the other factors such as the cost of electricty which is much higher per kWh compared to jet fuel, the cost of (replacing) the batteries and there is no business case.

The current tech is not there yet.
It's not that simple.

The turboprop is going to run at 75% power even at cruise altitude.
At altitude, the engines work just as hard per unit of time, hence produce as much power.
The lift to drag ratio doesn't change too much because you are flying at the same IAS, it's just that air being less dense, your TAS is higher. The point where you can reach the highest distance covered (km, mi or Nm) per unit of energy (kWh) is your optimum altitude.

So does an ATR72 cruise at 50% power?
Feather an engine and firewall the other one, then see if you can maintain your altitude...
Last edited by Waterbomber on Thu Dec 27, 2018 11:11 am, edited 1 time in total.
 
leghorn
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Re: Electric planes: the state of the art

Thu Dec 27, 2018 11:09 am

If what you were saying were true then electric cars wouldn't be able to get off their own driveway under their own power.
 
leghorn
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Re: Electric planes: the state of the art

Thu Dec 27, 2018 11:22 am

Tesla 2170 battery has considerably higher energy density than you are claiming.
 
Waterbomber
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Re: Electric planes: the state of the art

Thu Dec 27, 2018 11:23 am

leghorn wrote:
If what you were saying were true then electric cars wouldn't be able to get off their own driveway under their own power.


Except that electric cars don't have to worry about their lift/drag ratio and safety reserves...
The battery pack of Tesla Model S weighs over 500kg. A full gas tank on a diesel car weighs 50kg and has twice the range of a Model S.
The math adds up on my side.
You and others need to realise that fuel weight is a much bigger factor to an aircraft than it is to a car.

An ATR72 that has 3 hours + reserves worth of range would have less than 10 minutes worth of range at electric power. That's not even enough to clear the 30 minute final reserve, which would apply to any commercial aircraft regardless of what it's powered with.
 
leghorn
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Re: Electric planes: the state of the art

Thu Dec 27, 2018 11:30 am

You are throwing an awful lot of text on to the screen . What energy density are you claiming for lithium ion batteries.
You are also referring to battery types in autos which are no longer state of the art.
 
kalvado
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Re: Electric planes: the state of the art

Thu Dec 27, 2018 11:32 am

RJMAZ wrote:
Waterbomber wrote:
Except that the i3 is an electric car with an optional range extender.
As already discussed, any amount of aircraft can't take off with a battery pack as main source of energy.
The above hybrid with the gas turbine as main energy supply is a challenge as it is to justify.
The ATR72 has 3600kW of total engine output, of which it uses about 75% at cruise. With a range extender APU with 450kW of output you won't get far.

75% at cruise? That is 2700kw, where do you keep plucking these high power figures from? Cruise shaft horsepower is actually around 50% for a turboprop.

The ATR 72 with 70 passengers at 95kg can fly 850nm or 1574km. That is a takeoff fuel load of 2850kg. Minus landing fuel it consumes just under 5000lb of fuel on the trip.

A modern turboprop burns roughly 0.5lb of fuel for every shalf horsepower per hour.

The ATR cruises at 510km/h so that 850nm journey takes roughly 3.25 hours. 5000lb of fuel divided by 3.25 is 1500lb of fuel per hour. That means 3000hp average for the entire flight.

This figure doesnt take into account the much higher power and greater fuel consumption during climb. The 30 minute climb at full power represents 16% of the flight duration but burns 25% of the trip fuel. That means the ATR burns well below 3000hp on cruise. Definitely under 1800kw or 50% of maximum power.

I mentioned a 50 seat turboprop which is the ATR 42 in size. So a 787 sized APU acting as a 450kw range extender will probably add 40% range.

Maximum power is an elusive number here. It is limited by speed and altitude: higher air density on the ground means more air can enter combustion chamber, and more air available for prop to interact with; higher speed can help with more air in combustion chamber as well - but limits how much prop can push same air before going into speed of sound issues; and tips of the prop itself see higher airspeed - and same increased Mach numbers. While electric drive would avoid combustion chamber issues, prop *and fan) characteristics changing with the environment will be there.
So running at 80% of max engine power in cruise may mean having way less than 80% of power on the ground
 
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SheikhDjibouti
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Re: Electric planes: the state of the art

Thu Dec 27, 2018 11:39 am

RJMAZ wrote:
Actually one of the most simple hybrid systems would be to have a turbofan engine and place the electric motor on the same shaft just behind the fan.

The electric motor could then double the speed and thrust of the fan during takeoff. The electric motor can then freespin during cruise running entirely off the gas turbine.

The electric motor can then turn into a generator during descent abd there us your mechanically linked generator. So the gas turbine will be at full throttle during descent but most of the energy is being sucked out by the generator.
:checkmark: + :checkmark: + :checkmark:

RJMAZ wrote:
Such a design would still be 80% fossil fuel 20% electric like a Prius. As cool as this design sounds it won't please the environmentalists.
I think you will find most Prius drivers would argue against your 80:20 split. I'm saying nothing....

RJMAZ wrote:
I much prefer the BMW i3 style hybrid as it is 80% electric and 20% fossil fuel.
Using the the i3 style hybrid in an aircraft would work very well. If the flight was only 500kms long they could do it fully electric. If the flight is 1000kms long the generator has to run for the entire flight.
I'm liking this idea too, but it might need some refinement of the exact details.

RJMAZ wrote:
This generator would also provide the emergency reserve fuel. For instance if there is bad weather at the destination airport as soon as they get the call mid flight the generator would then get turned on to start extending range. The generator could be sized to provide 50% of the electrical power required at cruising altitude.
Sorry; this bit does not add up for me.
I'm seeing a finite supply of fuel. You can either use that to feed the main turbofans/gas turbines, to provide direct thrust.
Or
Alternatively you can use it to feed the turbofans/gas turbines to provide electrical energy for the batteries, that then feed the electrical motors, that then provide thrust, maybe at a later stage in the flight.

In practice, both outputs will probably exist in parallel, but you still only have a finite amount of fuel, and therefore a finite amount of thrust, hence no increase in range.

The only way it would possibly contribute to extended range is if, having charged the batteries as part of the normal cycle, instead of landing the a/c with full or part charged batteries (ready for a quick turnaround), you used very last drop of the accumulated battery power to provide another 30 minutes (¹) of low speed transit or loitering. Maintaining the aircraft marginally above stall speed requires far less power than full cruise speed, and extends the range because of lower drag. It is not commonly practised by current airliners because low speed flying is exactly what gas turbines and turbofans hate; they are distressingly fuel inefficient at lower speeds, whereas electric motors couldn't give a ****.
Of course having landed with fully drained batteries, the a/c now has to spend longer re-charging the units from ground supply, but that is a small price to pay for gaining a safety advantage, and will be the exception, not the general case..

(¹) No, I haven't calculated that "30" min figure with any precision; it could be just 15min, or it could be more. It is the general principle that I am trying to explain; the math can follow at a later date.
Nothing to see here; move along please.
 
kalvado
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Re: Electric planes: the state of the art

Thu Dec 27, 2018 11:41 am

SheikhDjibouti wrote:
kalvado wrote:
SheikhDjibouti wrote:
I have to say that I'm losing patience with you; it would appear you are trolling.!

A lot of duckspeak, no solid numbers in terms of $$/flight or lb fuel/flight.
Relax, take a deep breath, and try to prove your idea actually worth bytes wasted.
I disagree about the duckspeak, but I'll take your advice and try to chill out & relax.
I also come from a financial background (what is they say about accountants; "they know the price of everything, and the value of nothing"), but as far as I am concerned this is not about the $$$. It's about doing the right thing.
(before the usual suspects chime in; yes, of course costs are a factor, and the end solution must be a reasonable one.)

When catalytic converters and unleaded petrol were introduced/legislated/made mandatory, it wasn't sold on $$$. Even now catalytic converters add cost to a basic vehicle, and back then the original ones were horrendously expensive. Plus between them and unleaded petrol, vehicle performance was reduced. Do you recall the days when you could buy a Porsche or an Audi either with or without an optional catalytic converter? The latter option were 10-15 mph slower, and $3,000 more expensive. Not surprisingly many people argued against such a crazy idea at the time. And now here we are arguing over electric power for aircraft. Plus ça change, plus c'est la même chose. :roll:

Thankfully for the car industry, since then the technology has improved, performance has caught up (and some...), and the costs have dropped.

So, please forgive me if I am prepared to accept a reduction in absolute aircraft performance, and a marginal increase in airframe cost, in an attempt to mitigate the use of fossil fuels.

Since you don't like word duckspeak... OK, I'll say this is more bullshit instead of the technical argument. Which should be within the mindset of accounter.
Just make an effort and try to fill the worksheet:
Fuel consumption in descent is... and in most efficient engine conditions is ...
Power produced is... , and it could be produced by burning ... additional fuel
We can capture .... amount of energy in a form of electricity, and it would cost .... to get the same amount of power from the grid
Carrying this fuel around will burn ..... additional fuel at an extra cost of ....
Total cost of burned fuel is.... , which is ......(above/below) grid cost. total carbon emission is ....., compared to .... carbon emission due to grid generation of said power.

Then we're talking about something. THis would still be way incomplete, but a not so bad start for discussion.
 
Waterbomber
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Re: Electric planes: the state of the art

Thu Dec 27, 2018 11:42 am

leghorn wrote:
Tesla 2170 battery has considerably higher energy density than you are claiming.


At individual cell levels, specific energy density of li-ions is exceeding 250Wh per kg.
However, you need to remember that cells need to be put in packs and then they need to be interconnected, sensors, fixtures, protection from the elements, impacts and forces, etc... at the end of the day, you realise that a lot of weight is added to make it a working battery pack and the specific energy goes down by 20% or more.


I qlso invite you to scroll down to page 3 of the below document to realise that low temperature at altitude will be a real problem.
https://na.industrial.panasonic.com/sit ... asheet.pdf
 
leghorn
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Re: Electric planes: the state of the art

Thu Dec 27, 2018 12:13 pm

the Zoe I'm taking delivery of in 6 weeks time increased battery pack from 22kWh to 41 with only a 15kg weight increase. You overstate the issue.
 
leghorn
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Re: Electric planes: the state of the art

Thu Dec 27, 2018 12:35 pm

tesla 2170 cells are at about 280, not 250 and still well down on ncm811 batteries which are latest LG technology..
 
SeoulIncheon
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Re: Electric planes: the state of the art

Thu Dec 27, 2018 12:50 pm

kalvado wrote:
SheikhDjibouti wrote:
kalvado wrote:
A lot of duckspeak, no solid numbers in terms of $$/flight or lb fuel/flight.
Relax, take a deep breath, and try to prove your idea actually worth bytes wasted.
I disagree about the duckspeak, but I'll take your advice and try to chill out & relax.
I also come from a financial background (what is they say about accountants; "they know the price of everything, and the value of nothing"), but as far as I am concerned this is not about the $$$. It's about doing the right thing.
(before the usual suspects chime in; yes, of course costs are a factor, and the end solution must be a reasonable one.)

When catalytic converters and unleaded petrol were introduced/legislated/made mandatory, it wasn't sold on $$$. Even now catalytic converters add cost to a basic vehicle, and back then the original ones were horrendously expensive. Plus between them and unleaded petrol, vehicle performance was reduced. Do you recall the days when you could buy a Porsche or an Audi either with or without an optional catalytic converter? The latter option were 10-15 mph slower, and $3,000 more expensive. Not surprisingly many people argued against such a crazy idea at the time. And now here we are arguing over electric power for aircraft. Plus ça change, plus c'est la même chose. :roll:

Thankfully for the car industry, since then the technology has improved, performance has caught up (and some...), and the costs have dropped.

So, please forgive me if I am prepared to accept a reduction in absolute aircraft performance, and a marginal increase in airframe cost, in an attempt to mitigate the use of fossil fuels.

Since you don't like word duckspeak... OK, I'll say this is more bullshit instead of the technical argument. Which should be within the mindset of accounter.
Just make an effort and try to fill the worksheet:
Fuel consumption in descent is... and in most efficient engine conditions is ...
Power produced is... , and it could be produced by burning ... additional fuel
We can capture .... amount of energy in a form of electricity, and it would cost .... to get the same amount of power from the grid
Carrying this fuel around will burn ..... additional fuel at an extra cost of ....
Total cost of burned fuel is.... , which is ......(above/below) grid cost. total carbon emission is ....., compared to .... carbon emission due to grid generation of said power.

Then we're talking about something. THis would still be way incomplete, but a not so bad start for discussion.


You nailed it. Let's speak with real facts, not environmentalist propaganda. I also don't see any point in having hybrid system in airplanes.

I reckon that Sheikh relies on Prius analogy - and the main reason why Prius is efficient is that Prius has "regenerative brakes" that recoups kinetic energy when braking. Then cars brake and accelerate a lot - and Prius recoups kinetic energy when it brakes and then adds that power instead of burning extra fuel when Prius accelerates again. Therefore, a Prius or hybrid car benefits when it drives in urban setting (with a lot of stop signs and signals) but LOSES efficiency when driving in highway (not many stop signs and signals). A hybrid(e.g. GS450H/29 city-34 highway) has better urban fuel economy than a similar conventional car(BMW530I 24 city-34 highway) but highway economy will be similar.

An aircraft will "cruise" for most of flight stage and then brakes only once - during descent and landing. There is not much to be gained by using hybrid system. So Prius analogy simply won't work here.
 
kalvado
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Re: Electric planes: the state of the art

Thu Dec 27, 2018 1:39 pm

SheikhDjibouti wrote:
Did I read that last bit correctly?
Just exactly who do you think you are? The last idiot who spoke to me in such a condescending way …. nah, you're not worth it.

I am the one who is trying to keep this discussion technical and educative. You may shut me up on a forum - it is easy. But take my word for it, someday you will find yourself in a situation when you cannot shut up your opponent in a similar situation. Be it your boss, creditor, doctor, maintenance person - whoever has to deal with facts, not words.And it will hurt after all.
So, back on topic.
ANy technical calculations to back up your statements?
 
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SheikhDjibouti
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Re: Electric planes: the state of the art

Thu Dec 27, 2018 2:00 pm

SeoulIncheon wrote:
Let's speak with real facts, not environmentalist propaganda.
Good idea. And don't forget an open mind.
Oops, it appears that ship has already sailed.

SeoulIncheon wrote:
I reckon that Sheikh relies on Prius analogy
How strange; somebody else made that connection too, but using a totally different User ID. I guess it must be true then. Which is odd because I know a lot more about Formula1 (very big on regenerative braking :checkeredflag: ) than about Prius, like does it even have brakes; that's news to me. Of course, being a dyed in the wool environmentalist, I wouldn't approve of Formula 1. Which is odd because.... :lol:

SeoulIncheon wrote:
- and the main reason why Prius is efficient is that Prius has "regenerative brakes" that recoups kinetic energy when braking. Then cars brake and accelerate a lot ..
An aircraft will "cruise" for most of flight stage and then brakes only once - during descent and landing. There is not much to be gained by using hybrid system.

Are you sure about that? "An aircraft will cruise for most of flight stage..."??

Have you ever flown on "an aircraft"? They are not all the same.

Perhaps I should re-phrase that; have you ever flown on a REGIONAL aircraft? Have you ever flown on a regional aircraft outside of the contiguous USA?
Say island hopping with Hawaiian Airliness? Or almost anywhere in Europe or Asia?

HA340 is possibly an extreme case, scheduled for 34 mins. I've watched it on FR24 and clocked somewhere around just 4-6 minutes in the cruise.
HA148 travels nearly twice as far over 50 mins, but still only manages 5 -7 mins at cruise.

That is a long way from "most" of the time; and Hawai'i is by no means unique.
SeoulIncheon wrote:
Let's speak with real facts, not environmentalist propaganda.
Consider yourself pwned. :lol:
Nothing to see here; move along please.
 
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SheikhDjibouti
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Re: Electric planes: the state of the art

Thu Dec 27, 2018 2:13 pm

kalvado wrote:
I am the one who is trying to keep this discussion technical and educative. You may shut me up on a forum - it is easy.
How so? It hasn't worked so far.....

Besides, I genuinely welcome your constructive comments/criticism. It's just the pfaff and insults I could do without. Such as talking down to me in a condescending (you might need to google that word) manner, as if you were my boss.

kalvado wrote:
But take my word for it, someday you will find yourself in a situation when you cannot shut up your opponent in a similar situation. Be it your boss, creditor, doctor, maintenance person - whoever has to deal with facts, not words.And it will hurt after all.
I told my boss where he could shove his job over 20 years ago. I don't have any creditors. Maintenance - I'm skilled enough to do most of that myself, and if I need something beyond that, I get on with folks just fine. Sometimes they learn something from me, and sometimes I learn something from them. Isn't that what everybody does?

You might have a point about my Doctor though; I'll have to ask him next time he comes around grovelling to me for a favor. :lol:

kalvado wrote:
ANy technical calculations to back up your statements?
I suggest you scroll back and read all my earlier posts; they're full of real world data, backed up with sources so that you can check for yourself. I see no need to go through it all again, just for you, even though you have asked so very nicely.
Nothing to see here; move along please.
 
frmrCapCadet
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Re: Electric planes: the state of the art

Thu Dec 27, 2018 2:53 pm

Prius high voltage batteries seem to be lasting upwards of 200,000 miles. Many drivers a lot better mileage than the EPA listed. I did, and was never shy about accelerating when needed. There are twists and turns in energy conservation. Most recent car was a small SUV(non-hybrid), which likely will get over 30 mpg. Only reason I switched was wanting the new safety features.

Airbus and Boeing obviously think it will happen, but for their large (and yes, even the 737/320 are now large planes) it is far off in the future. But many of us think that better smaller shorter range planes will be trans-formative for the transportation system.
Buffet: the airline business...has eaten up capital...like..no other (business)
 
leghorn
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Re: Electric planes: the state of the art

Thu Dec 27, 2018 3:38 pm

With the disruptive change of reduced costs on 80 to 100 seater planes the LCC A321 and 737 fleets will not be able to drive Q400 sized planes off routes.
 
planewasted
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Re: Electric planes: the state of the art

Thu Dec 27, 2018 4:15 pm

Waterbomber wrote:
leghorn wrote:
Tesla 2170 battery has considerably higher energy density than you are claiming.


At individual cell levels, specific energy density of li-ions is exceeding 250Wh per kg.
However, you need to remember that cells need to be put in packs and then they need to be interconnected, sensors, fixtures, protection from the elements, impacts and forces, etc... at the end of the day, you realise that a lot of weight is added to make it a working battery pack and the specific energy goes down by 20% or more.


I qlso invite you to scroll down to page 3 of the below document to realise that low temperature at altitude will be a real problem.
https://na.industrial.panasonic.com/sit ... asheet.pdf


Fueltanks, pumps, safety systems and plumbing also weights a lot.
And for the cold temperatures, I think the self heating due to the rapid discharge will be enough if some insulation are added.
Planes can fly 20 hours on jetfuel today. So a 1 hour endurance electric plane is not THAT far away.
 
Waterbomber
Posts: 849
Joined: Sat Jul 09, 2016 11:51 am

Re: Electric planes: the state of the art

Fri Dec 28, 2018 3:02 am

planewasted wrote:
Waterbomber wrote:
leghorn wrote:
Tesla 2170 battery has considerably higher energy density than you are claiming.


At individual cell levels, specific energy density of li-ions is exceeding 250Wh per kg.
However, you need to remember that cells need to be put in packs and then they need to be interconnected, sensors, fixtures, protection from the elements, impacts and forces, etc... at the end of the day, you realise that a lot of weight is added to make it a working battery pack and the specific energy goes down by 20% or more.


I qlso invite you to scroll down to page 3 of the below document to realise that low temperature at altitude will be a real problem.
https://na.industrial.panasonic.com/sit ... asheet.pdf


Fueltanks, pumps, safety systems and plumbing also weights a lot.
And for the cold temperatures, I think the self heating due to the rapid discharge will be enough if some insulation are added.
Planes can fly 20 hours on jetfuel today. So a 1 hour endurance electric plane is not THAT far away.


So how far does 1 hour of endurance get you?
1 hour endurance minus diversion, holding and final reserves equals zero endurance.

Jet fuel powered aircraft are reaching towards 20 hours of range. However, don't forget that your batteries won't get much lighter towards the end of the flight, which is the case with jet fuel.

Self heating due to rapid discharge has already been addressed. Heat is waste, no matter whether you talk about internal resistance or adding a heating system.
The generated heat is waste and reduces efficiency.

The difference between current battery tech and jet fuel is so big, it's like suggesting to power cars with pedals. Yabadabadoo.

Don't let yourself be manipulated by the ongoing electric car frenzy. Tesla, Nissan and all the others are selling an illusion. Electric cars existed 2 centuries ago. 200 years my friends.
They are toying with an old idea and making it look sexy. In the meanwhile, electricity prices are going through the roof while it is a basic necessity and not even half of it is produced in a renewable way.
If you want to contribute with your mind, you need to look far beyond what is suggested on here, keep your mouth shut until you get a patent on it (watch out for invention secrecy orders) and then sell it to the world.
 
User avatar
Nomadd
Posts: 247
Joined: Sat Dec 09, 2017 3:26 pm

Re: Electric planes: the state of the art

Fri Dec 28, 2018 4:01 am

leghorn wrote:
the Zoe I'm taking delivery of in 6 weeks time increased battery pack from 22kWh to 41 with only a 15kg weight increase. You overstate the issue.

So, you think you're going to get 19kwh more capacity for 15kg weight with a 250wh (usable) per kg battery?
Did you do the math for the million man march?
 
Beatyair
Posts: 856
Joined: Mon Feb 10, 2014 9:09 pm

Re: Electric planes: the state of the art

Fri Dec 28, 2018 4:13 am

Remember all the fires on the 787’s due to batteries? Yes, batteries are getting better, but I will wait until things are perfect before flying on one. The other problem is that nobody know what to do with batteries after they are done. How to deal with problem.
 
Some1Somewhere
Posts: 28
Joined: Thu Jun 25, 2015 2:22 pm

Re: Electric planes: the state of the art

Fri Dec 28, 2018 5:35 am

Lead-acid batteries already have an upwards of 95% recycling rate. I wouldn't be surprised if that's better than airframes currently.

Lithiums aren't there yet, which looks largely to be down to the present small size and varied chemistries of most consumer lithium batteries. With fifty-ton-plus batteries, the situation would be very different.

SeoulIncheon wrote:
You nailed it. Let's speak with real facts, not environmentalist propaganda. I also don't see any point in having hybrid system in airplanes.

I reckon that Sheikh relies on Prius analogy - and the main reason why Prius is efficient is that Prius has "regenerative brakes" that recoups kinetic energy when braking. Then cars brake and accelerate a lot - and Prius recoups kinetic energy when it brakes and then adds that power instead of burning extra fuel when Prius accelerates again. Therefore, a Prius or hybrid car benefits when it drives in urban setting (with a lot of stop signs and signals) but LOSES efficiency when driving in highway (not many stop signs and signals). A hybrid(e.g. GS450H/29 city-34 highway) has better urban fuel economy than a similar conventional car(BMW530I 24 city-34 highway) but highway economy will be similar.

An aircraft will "cruise" for most of flight stage and then brakes only once - during descent and landing. There is not much to be gained by using hybrid system. So Prius analogy simply won't work here.

My understanding is that the Prius is roughly equally efficient on the highway - it has unusually good aerodynamics (but that's unrelated to the power train), but the electric side of the power train can be pretty much switched out. It's nothing more than a small amount of dead mass, which isn't much of an issue in cars.

Where electric really shines is at idle. Having the main engines shut down from vacating the runway until lining up again (or a few minutes before, for warm up) would be far more likely to save fuel, even if it was just motors run off the APU.
 
RJMAZ
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Joined: Sat Jul 09, 2016 2:54 am

Re: Electric planes: the state of the art

Fri Dec 28, 2018 6:04 am

I just thought of the biggest negative to electric planes. Airport fees.

Airport fees are based off the aircraft weight. The electric plane will have be more than twice the weight to get the same job done.

Even if the electricity was free the electeic plane would cost significantly more. Obviously the only way to combat this would be for financial incentives by local governments.
 
parapente
Posts: 3061
Joined: Tue Mar 28, 2006 10:42 pm

Re: Electric planes: the state of the art

Fri Dec 28, 2018 9:49 am

Re RJMAZ - yup they will have to change the way they calculate - am sure they will.
With cars we seem to be leaving the first phase of hybrid electric behind ( 20 years approx) and moving towards all electric As range/charging points ( home and away) is nearly getting to the point where range angst is diminishing.However this genuine fear has been the main stumbling block for electric cars.

Now just imagine that fear translated to something flying in the air! No perking by the kerb ,just a straight crash to oblivion.No one will do it imho.
Sooooo
It has to be hybrid - at least to start with for this reason and yes technical limitations of energy storage.
As someone who lives in the heart of a city there always seems to be 2 views on 'environmental change' and the vehicle
1. Is the CO2 climate change argument.
2. Is the general pollutant argument.Primarily atmospheric pollution from hydrocarbon burn ,but also noise.They say ( in London) it causes over 20k premature deaths PA.Whether this is true I don't know but it come from the BMA.

Seems to me that a hybrid aircaft can do a lot for area 2. At T/O the batteries are fully charged and do much of the work getting the craft up to altitude.This would reduce both pollution and noise around the city.
At cruise the ICE engines can be optimised thus reducing pollution by about half.
The batteries can be part regenerated in cruise but mainly through the potential energy of coming down from 30k feet.( lot of energy there).
The landing can therefore be achieved primarily on electric power again reducing noise and pollution around the city area.

The passenger always knows he has a trusty turbine on board to eliminate any power shortages,thus eliminating 'range angst ' which is imho critical.
 
leghorn
Posts: 903
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Re: Electric planes: the state of the art

Fri Dec 28, 2018 10:06 am

Nomadd wrote:
leghorn wrote:
the Zoe I'm taking delivery of in 6 weeks time increased battery pack from 22kWh to 41 with only a 15kg weight increase. You overstate the issue.

So, you think you're going to get 19kwh more capacity for 15kg weight with a 250wh (usable) per kg battery?
Did you do the math for the million man march?

Why don't you go and search for details on the differences between a 22kWh and 41 kWh Renault Zoe before you try trolling me. Your belligerent approach to posting is unhelpful to discussion of the topic. Please attend to this.
 
WIederling
Posts: 8888
Joined: Sun Sep 13, 2015 2:15 pm

Re: Electric planes: the state of the art

Fri Dec 28, 2018 10:51 am

leghorn wrote:
Nomadd wrote:
leghorn wrote:
the Zoe I'm taking delivery of in 6 weeks time increased battery pack from 22kWh to 41 with only a 15kg weight increase. You overstate the issue.

So, you think you're going to get 19kwh more capacity for 15kg weight with a 250wh (usable) per kg battery?
Did you do the math for the million man march?

Why don't you go and search for details on the differences between a 22kWh and 41 kWh Renault Zoe before you try trolling me. Your belligerent approach to posting is unhelpful to discussion of the topic. Please attend to this.


https://pushevs.com/2016/10/09/renault- ... y-details/

pushev wrote:
First generation battery:
Total weight is 290 kg (280 kg are quoted in the video, but in every other source is 290 kg)
Total capacity is 25,92 kWh (192 x 36 Ah x 3,75 V = 25,92 kWh)
Available capacity is 23,3 kWh
192 cells, each with 36 Ah nominal capacity and 3,75 V nominal voltage
Total cell weight is 165,12 kg (192 x 0,86 kg = 165,12 kg)

Second generation battery:
Total weight is 305 kg
Total capacity is 45,61 kWh (estimation by knowing the usable capacity)
Available capacity is 41 kWh
192 cells, each with 63,35 Ah nominal capacity (estimation) and 3,75 V nominal voltage
Total cell weight is 180,12 kg (estimation by knowing the total battery weight)


taking the net cell weight : energy/weight went up from 157Wh/kg to 256Wh/kg
( large factor here will be more active material per cell in relation to the cell "hull".)
Murphy is an optimist
 
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SheikhDjibouti
Posts: 1773
Joined: Sat Sep 30, 2017 4:59 pm

Re: Electric planes: the state of the art

Fri Dec 28, 2018 12:23 pm

RJMAZ wrote:
I just thought of the biggest negative to electric planes. Airport fees.

Airport fees are based off the aircraft weight. The electric plane will have be more than twice the weight to get the same job done.

The biggest negative? Really?

Would you like to know the biggest negative to driving an electric car in London?
You don't have to pay the Congestion Charge.

Oh, wait.... :o

As for "the electric plane will have to be more than twice the weight.....", I would love to see your figures, because you obviously know something
the rest of us have missed. I think most of us would agree on "heavier", but to be quite so certain that it is "more than twice the weight" suggests you have got an agenda.
Nothing to see here; move along please.
 
RJMAZ
Posts: 1636
Joined: Sat Jul 09, 2016 2:54 am

Re: Electric planes: the state of the art

Fri Dec 28, 2018 12:35 pm

SheikhDjibouti wrote:
As for "the electric plane will have to be more than twice the weight.....", I would love to see your figures, because you obviously know something
the rest of us have missed. I think most of us would agree on "heavier", but to be quite so certain that it is "more than twice the weight" suggests you have got an agenda.

Multiple users have already calculated it on page two and three. You might want go back and have a read as it was broken down to the finest detail.
 
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SheikhDjibouti
Posts: 1773
Joined: Sat Sep 30, 2017 4:59 pm

Re: Electric planes: the state of the art

Fri Dec 28, 2018 1:11 pm

Waterbomber wrote:
I qlso invite you to scroll down to page 3 of the below document to realise that low temperature at altitude will be a real problem.
https://na.industrial.panasonic.com/sit ... asheet.pdf

planewasted wrote:
And for the cold temperatures, I think the self heating due to the rapid discharge will be enough if some insulation are added.

Waterbomber wrote:
Self heating due to rapid discharge has already been addressed.
Oh no it wasn't!
I let you get away with it last time because I cba to blow your comments out of the water, but since you've dragged it up again...
When Panasonic state their 18650 cell has 3600mAh capacity; that is exactly what you get. Otherwise they would sell you the same cell as a "4000mAh" unit with an tiny asterisk denoting the 400mAh you are going to lose due to the internal resistance.

p.s. You quote Panasonic's data sheet above, so do you have a figure for internal resistance for these units? I do...… but you're the one making this claim, so you can find it for yourself. :lol:
Waterbomber wrote:
Heat is waste, no matter whether you talk about internal resistance or adding a heating system. The generated heat is waste and reduces efficiency.

Up thread, somebody pointed out the need for a heating circuit for the passenger cabin, because the usual source was waste heat from traditional jet engines and gas turbines. I invite you to think hard who that might have been. :biggrin: They used this argument to say that waste heat from jet engines was useful. But now you say the opposite.
But if heat comes from internal resistance and is excluded from the stated battery capacity, it can be used to maintain the batteries and heat the passenger cabin for free, and that makes it even better than the current system. Score one for electric! :rotfl:

If you want to look at it a different way; what amount of energy is "wasted" producing condensation trails at altitude. You won't get that "waste" from electric engines. ( I wait to be corrected on that; I don't recall anyone ever mentioning it before...)

Waterbomber wrote:
Don't let yourself be manipulated by the ongoing electric car frenzy. Tesla, Nissan and all the others are selling an illusion.
Electric cars existed 2 centuries ago. 200 years my friends.
200 years ago, really? That pre-dates rechargeable batteries and everything. Show me!
It is such a shame that the valid points you make are diluted by hyperbole, exaggeration, and propaganda. It also leads one to believe that your math isn't quite up to scratch, which kinda undermines many of your arguments.
Wikipdedia wrote:
In 1884....., Thomas Parker built the first practical production electric car in London using his own specially designed high-capacity rechargeable batteries

Unless I have been over-sleeping a lot, we are currently still in 2018 (just), and that makes it a lot less than 200 years ago "my friend". :lol:
Nothing to see here; move along please.
 
parapente
Posts: 3061
Joined: Tue Mar 28, 2006 10:42 pm

Re: Electric planes: the state of the art

Fri Dec 28, 2018 1:19 pm

As for weight we really don't know -if- one accepts ( as I do) that one will have to wait for solid metal lithium batteries ( with ceramic sandwich layer Or similar) to arrive in 5-10 years time.I don't believe anyone ( none have been mass produced) can know. What the weight actually will be.
As for the aircaft itself.If one took the EasyJet exapmple or Alice or indeed the NASA/Boeing work. All have exotic new ways to optimise an electric or hybrid aircaft.They are all vastly different to today's aircraft with different distributed thrust systems.As such someone would have to make a vast investment.
That someone can ( in practice) only be Airbus or Boeing if it were to be a (say) 75-100 seater - which it would need to be to be commercially viable.
Both companies have just taken over 2 companies with 'new' regional jets.So any big investment must ( surely) be a decade away at least -unless-
Elon Musk!
But even he has said electric aircraft are not possible at the moment ( commercially) and if there was anyone on the planet I would believe vis a vis electric propulsion it would be him.
Sadly don't think I will see an electric commercial airliner in my lifetime.But always hoping there may be a breakthrough.
 
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SheikhDjibouti
Posts: 1773
Joined: Sat Sep 30, 2017 4:59 pm

Re: Electric planes: the state of the art

Fri Dec 28, 2018 1:55 pm

RJMAZ wrote:
SheikhDjibouti wrote:
As for "the electric plane will have to be more than twice the weight.....", I would love to see your figures,
….most of us would agree on "heavier", but to be quite so certain that it is "more than twice the weight" suggests you have got an agenda.

Multiple users have already calculated it on page two and three. You might want go back and have a read as it was broken down to the finest detail.

Multiple users.... that is a lie. I should report your post for deliberate mis-information.

It was you RJMAZ; so all you are doing here is self-referencing yourself.
Well now, …. me, and my shadow BOTH agree you're wrong. So that's 2:1 and you are outvoted. :lol:

Seriously though, if you still feel your numbers stand up (even after criticism from various sources, including myself), then take this opportunity to re-state them, with an emphasis on how they add up to "more than double the weight". Either you stand by your assertion, or not.

But before you do that.....
RJMAZ wrote:
The C-130 has excellent takeoff performance ita wing is as big as a 757 but is lighter than a 737. It also has a very strong landing gear that would allow a significant MTOW increase. So we will raise the MTOW up to 90T

I queried that at the time, along with the small matter of MLW being the same, and you replied...
RJMAZ wrote:
That is why you start with a tactical transport plane like the C-130. Its landing gear is extremely overbuilt to handle rough austere gravel and massive sink rates to reduce landing role. It is effecticely crashing into the ground, this downward momemtum amplifies the actual landing weight probably pushing loads well above a 90T gentle airliner landing.

If your original data " was broken down to the finest detail.", you might want to inform Lockheed they've got their numbers wrong.
C-130J
Max. Normal Landing Weight 58,965 kg
Max. Overload Landing Weight 70,305 kg
(which coincidentally is also MTOW)
Nothing to see here; move along please.
 
planewasted
Posts: 527
Joined: Thu Jan 17, 2008 11:47 pm

Re: Electric planes: the state of the art

Fri Dec 28, 2018 2:05 pm

Waterbomber wrote:
So how far does 1 hour of endurance get you?
1 hour endurance minus diversion, holding and final reserves equals zero endurance.

Jet fuel powered aircraft are reaching towards 20 hours of range. However, don't forget that your batteries won't get much lighter towards the end of the flight, which is the case with jet fuel.

Self heating due to rapid discharge has already been addressed. Heat is waste, no matter whether you talk about internal resistance or adding a heating system.
The generated heat is waste and reduces efficiency.

The difference between current battery tech and jet fuel is so big, it's like suggesting to power cars with pedals. Yabadabadoo.

Don't let yourself be manipulated by the ongoing electric car frenzy. Tesla, Nissan and all the others are selling an illusion. Electric cars existed 2 centuries ago. 200 years my friends.
They are toying with an old idea and making it look sexy. In the meanwhile, electricity prices are going through the roof while it is a basic necessity and not even half of it is produced in a renewable way.
If you want to contribute with your mind, you need to look far beyond what is suggested on here, keep your mouth shut until you get a patent on it (watch out for invention secrecy orders) and then sell it to the world.


There are some more "low" hanging fruits to increase the endurance. For example:
Fly slower with an higher aspect ratio wing? Lets say 25 % increase range?
Make the cabin non pressurized. Saved a few tons? 10% endurance?
Remove the pilots and cockpit, fly autonomously. 10% for a small plane? Huge operating cost reduction for a small plane. Very good for a small commuter plane.

For short hops between small rural cities this plane can make sense. Cost of building and maintaining roads and railroads are very expensive per person if there is little traffic.
I think it is almost doable with today's technology. Problem is that it won't make sense on the cost side. Yet...

Here in Sweden, they want to build high speed rails between small cities for more than the cost of the entire A380 program. I wish they could try to make an extremely efficient small commuter plane instead... But I am also an aviation geek. :)

Edit: And about the heating issue. In worst case, just use a few liters of diesel and a diesel heater. It will be enough to heat a commuter plane for a 1 hour flight.
 
frmrCapCadet
Posts: 3144
Joined: Thu May 29, 2008 8:24 pm

Re: Electric planes: the state of the art

Fri Dec 28, 2018 3:04 pm

Some of us have wanted a dedicated helicopter section here. There was a bit of a stir when some company announced a new technology model. There web site was distinctly uninformative. I used their 'contact' link and suggested they needed to be just a little more informative. No response. Drones with 4-6 motors and blade sets look like an intriguing model for very short hops, say under 25 miles. Maybe hybrid, quiet, mechanically simple, reliable (all the complications in the computers and programs). I don't know if such a plane would be aerodynamically possible.
Buffet: the airline business...has eaten up capital...like..no other (business)
 
PPVRA
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Joined: Fri Nov 12, 2004 7:48 am

Re: Electric planes: the state of the art

Fri Dec 28, 2018 3:50 pm

Extending range for an emergency isn’t enough. You have to consider...

1. A go-around, which will use almost as much energy as a regular takeoff.
2. Climb to altitude, which is energy intensive.
3. Then fly back to the runway or to another airport possibly 100 miles away with better weather, and...
4. Reserve energy on top of that to allow 45 minutes of flight.

Recalculate....


Not mention, you can add drag with generators on descent all you want. But grandma isnt interested in flying DiveBomb Airlines, because that extra drag will require more gravity to maintain speed. And speed is life in airplanes.
"If goods do not cross borders, soldiers will" - Frederic Bastiat
 
RJMAZ
Posts: 1636
Joined: Sat Jul 09, 2016 2:54 am

Re: Electric planes: the state of the art

Fri Dec 28, 2018 4:16 pm

SheikhDjibouti wrote:
RJMAZ wrote:
Multiple users have already calculated it on page two and three. You might want go back and have a read as it was broken down to the finest detail.

Multiple users.... that is a lie. I should report your post for deliberate mis-information.

It was you RJMAZ; so all you are doing here is self-referencing yourself.
Well now, …. me, and my shadow BOTH agree you're wrong. So that's 2:1 and you are outvoted. :lol:


Are you OK?

Here is waterbomber doing an A321 with a MTOW six times higher

Waterbomber wrote:
Let's imagine that they fit an A321 fuselage on an A380 wing, how far would it be able to fly?

*insert big calculation*

So basically, a 280 ton battery pack fitted to an A380 with an A321 fuselage would have enough capacity to power a single A380 engine for an hour if the engines can operate at 100% efficiency.
For all 4 engines, only 15 minutes...


And another user hitower3 also calculated an a320 needs a massive 63.5T battery to fly 1000nm, considering an A320 only weighs 42T..

So you have your multiple users.

SheikhDjibouti wrote:
If your original data " was broken down to the finest detail.", you might want to inform Lockheed they've got their numbers wrong.
C-130J
Max. Normal Landing Weight 58,965 kg
Max. Overload Landing Weight 70,305 kg
(which coincidentally is also MTOW)


No need to inform lockheed I have already explained why the C-130 can land heavier in this very thread.

RJMAZ wrote:
Actually the C-130 with ATR takes the high landing weight into account.

That is why you start with a tactical transport plane like the C-130. Its landing gear is extremely overbuilt to handle rough austere gravel and massive sink rates to reduce landing roll. It is effecticely crashing into the ground, this downward momemtum amplifies the actual landing weight probably pushing loads well above a 90T gentle airliner landing.

The pavement loading is very low. So the added weight isn't a problem.


Kalvado, AirFiero and Waterbomber have already shut down your crazy hybrid ideas yet you continue.

As Kalvado said "your design concept is crap."

As I said any electric design will have to be minimum double the weight of a conventional design of similar capacity. If you can't agree with that you are crazy.
 
leghorn
Posts: 903
Joined: Sun Jan 22, 2017 9:13 am

Re: Electric planes: the state of the art

Fri Dec 28, 2018 8:48 pm

WIederling wrote:
leghorn wrote:
Nomadd wrote:
So, you think you're going to get 19kwh more capacity for 15kg weight with a 250wh (usable) per kg battery?
Did you do the math for the million man march?

Why don't you go and search for details on the differences between a 22kWh and 41 kWh Renault Zoe before you try trolling me. Your belligerent approach to posting is unhelpful to discussion of the topic. Please attend to this.


https://pushevs.com/2016/10/09/renault- ... y-details/

pushev wrote:
First generation battery:
Total weight is 290 kg (280 kg are quoted in the video, but in every other source is 290 kg)
Total capacity is 25,92 kWh (192 x 36 Ah x 3,75 V = 25,92 kWh)
Available capacity is 23,3 kWh
192 cells, each with 36 Ah nominal capacity and 3,75 V nominal voltage
Total cell weight is 165,12 kg (192 x 0,86 kg = 165,12 kg)

Second generation battery:
Total weight is 305 kg
Total capacity is 45,61 kWh (estimation by knowing the usable capacity)
Available capacity is 41 kWh
192 cells, each with 63,35 Ah nominal capacity (estimation) and 3,75 V nominal voltage
Total cell weight is 180,12 kg (estimation by knowing the total battery weight)


taking the net cell weight : energy/weight went up from 157Wh/kg to 256Wh/kg
( large factor here will be more active material per cell in relation to the cell "hull".)

They are actually battery pouches not conventional CYLINDRICAL cells as you would imagine in any other EV
 
WIederling
Posts: 8888
Joined: Sun Sep 13, 2015 2:15 pm

Re: Electric planes: the state of the art

Fri Dec 28, 2018 9:04 pm

leghorn wrote:
They are actually battery pouches not conventional CYLINDRICAL cells as you would imagine in any other EV


If you go over the video they aren't "pouches" like in RC model LiPo batteries either.
more like the prismatic cells you can get from Winston and its competitors.
Murphy is an optimist
 
Waterbomber
Posts: 849
Joined: Sat Jul 09, 2016 11:51 am

Re: Electric planes: the state of the art

Sat Dec 29, 2018 1:07 am

SheikhDjibouti wrote:
Waterbomber wrote:
I qlso invite you to scroll down to page 3 of the below document to realise that low temperature at altitude will be a real problem.
https://na.industrial.panasonic.com/sit ... asheet.pdf

planewasted wrote:
And for the cold temperatures, I think the self heating due to the rapid discharge will be enough if some insulation are added.

Waterbomber wrote:
Self heating due to rapid discharge has already been addressed.
Oh no it wasn't!
I let you get away with it last time because I cba to blow your comments out of the water, but since you've dragged it up again...
When Panasonic state their 18650 cell has 3600mAh capacity; that is exactly what you get. Otherwise they would sell you the same cell as a "4000mAh" unit with an tiny asterisk denoting the 400mAh you are going to lose due to the internal resistance.

p.s. You quote Panasonic's data sheet above, so do you have a figure for internal resistance for these units? I do...… but you're the one making this claim, so you can find it for yourself. :lol:
Waterbomber wrote:
Heat is waste, no matter whether you talk about internal resistance or adding a heating system. The generated heat is waste and reduces efficiency.

Up thread, somebody pointed out the need for a heating circuit for the passenger cabin, because the usual source was waste heat from traditional jet engines and gas turbines. I invite you to think hard who that might have been. :biggrin: They used this argument to say that waste heat from jet engines was useful. But now you say the opposite.
But if heat comes from internal resistance and is excluded from the stated battery capacity, it can be used to maintain the batteries and heat the passenger cabin for free, and that makes it even better than the current system. Score one for electric! :rotfl:

If you want to look at it a different way; what amount of energy is "wasted" producing condensation trails at altitude. You won't get that "waste" from electric engines. ( I wait to be corrected on that; I don't recall anyone ever mentioning it before...)

Waterbomber wrote:
Don't let yourself be manipulated by the ongoing electric car frenzy. Tesla, Nissan and all the others are selling an illusion.
Electric cars existed 2 centuries ago. 200 years my friends.
200 years ago, really? That pre-dates rechargeable batteries and everything. Show me!
It is such a shame that the valid points you make are diluted by hyperbole, exaggeration, and propaganda. It also leads one to believe that your math isn't quite up to scratch, which kinda undermines many of your arguments.
Wikipdedia wrote:
In 1884....., Thomas Parker built the first practical production electric car in London using his own specially designed high-capacity rechargeable batteries

Unless I have been over-sleeping a lot, we are currently still in 2018 (just), and that makes it a lot less than 200 years ago "my friend". :lol:


There is a point where the discussion starts going in circles.

The cabin is currently not heated by waste heat from the engines, that would suggest that the waste heat is recycled. The cabin heating is direct waste.
This would be no different if the aircraft would be powered by batteries.
Currently fuel is heated by fuel-oil heat exchangers. Heat wasted by the engines is recycled to heat fuel. But compared to batteries, fuel doesn't need much heating.

About the heat wasted in turbofan exhaust, this is already accounted for when we say that electric motors are twice as efficient as turbofan engines for the sake of comparison.
In reality it's inappropriate to compare the efficiency of a turbofan with that of an AC motor.
A turbofan or turboprop includes the propulsive means (the fan or prop) while the AC motor doesn't have propulsive means, so you still need to account for propulsive loss.
So the only appropriate comparison is a turbofan vs. an electrically driven fan, or turboprop vs. an electrically driven prop. I think that the propulsive efficiency of the most recent turbofans is such that they would not require twice as much as energy as an electrically powered fan to produce the same thrust.

Less and less heat is wasted by gas turbine engines as they progress.
AC motors also waste heat by the way. Obviously not as much. However, if the electricity is generated by burning fossil fuels, the heat is wasted at source, so the end result is the same, if not worse.

Electric cars existed as early as 1828.
Cf your wikipedia page. https://en.m.wikipedia.org/wiki/History ... ic_vehicle

I think that there is still a loooooooot of progress possible. In a century people reading this thread will be laughing.

My point is not that electric planes are impossible. I'm just saying that lithium batteries as we know them today do not make them possible and the current vehicle frenzy based on this technology is a distraction from the real possibilities.
 
jagraham
Posts: 926
Joined: Sun Jul 17, 2016 11:10 pm

Re: Electric planes: the state of the art

Sat Dec 29, 2018 2:15 am

There is another approach - the Solar Impulse approach.

If a combination of efficient thrust generation, high lift / low drag, and large area for solar panels (satellite >40% efficiency type), can provide about half the power for a plane to get to 250 knots with a reasonable payload, it works.

The Solar Impulse II definitely has the range. But not the payload, not the speed, not the ease of use and handling.

Consider that the Wright brothers first flight was about 120 feet.

If God had meant man to fly, He would have given man a brain. Somebody sometime will figure this out.
 
RJMAZ
Posts: 1636
Joined: Sat Jul 09, 2016 2:54 am

Re: Electric planes: the state of the art

Sat Dec 29, 2018 2:36 am

Waterbomber wrote:
Currently fuel is heated by fuel-oil heat exchangers. Heat wasted by the engines is recycled to heat fuel. But compared to batteries, fuel doesn't need much heating.

Again the batteries don't need heating.

Tesla has to cool the batteries. Cooling is the biggest problem limiting their performance yet you keep going on about heaters.

A Tesla car with normal driving will drain their batteries in 5-6 hours. An electric plane will drain its batteries in 1-2 hours. The rate of discharge determines how hot the battery gets.

The batteries will be hottest at the top of climb. The cool air will passively cool the batteries and stop them from exploding.

The biggest problem would be if there was an emergency a minute after takeoff. The batteries wont get a chance to be cooled at high altitude so they could easily overheat if the aircraft doesn't land quickly.

This link below shows how the Tesla battery pack overheats to dangerous levels within 5 minutes of high speed driving.

https://insideevs.com/electric-gt-tesla ... nd-a-half/

Also note the fastest Tesla can only lap the Nurburgring as fast as an MX-5 and Volkswagen Golf GTI. This is 2+ minutes slower than the Lambo, Porsche and Ferrari cars as the Tesla can only do it at 25% power otherwise the batteries overheat. If Tesla try to race in the cool air of winter then they dont have enoigh grip from the cold tyres.

As the batteries at the top of climb will be hot and the cruise power draw is still significant then the batteries will never cool down. During a traditional descent the batteries might cool down but you can just change the flight profile. Instead of having a gradual glide down at very low power the aircraft could continue at higher speeds and altitude for longer. The electric aircraft has the unique ability to make the engines windmill and recharge the batteries on descent. This process would cause significant drag and allow for the plane to descend very rapidly without overspeeding.
 
Waterbomber
Posts: 849
Joined: Sat Jul 09, 2016 11:51 am

Re: Electric planes: the state of the art

Sat Dec 29, 2018 3:02 am

RJMAZ wrote:
Waterbomber wrote:
Currently fuel is heated by fuel-oil heat exchangers. Heat wasted by the engines is recycled to heat fuel. But compared to batteries, fuel doesn't need much heating.

Again the batteries don't need heating.

Tesla has to cool the batteries. Cooling is the biggest problem limiting their performance yet you keep going on about heaters.

A Tesla car with normal driving will drain their batteries in 5-6 hours. An electric plane will drain its batteries in 1-2 hours. The rate of discharge determines how hot the battery gets.

The batteries will be hottest at the top of climb. The cool air will passively cool the batteries and stop them from exploding.

The biggest problem would be if there was an emergency a minute after takeoff. The batteries wont get a chance to be cooled at high altitude so they could easily overheat if the aircraft doesn't land quickly.

This link below shows how the Tesla battery pack overheats to dangerous levels within 5 minutes of high speed driving.

https://insideevs.com/electric-gt-tesla ... nd-a-half/

Also note the fastest Tesla can only lap the Nurburgring as fast as an MX-5 and Volkswagen Golf GTI. This is 2+ minutes slower than the Lambo, Porsche and Ferrari cars as the Tesla can only do it at 25% power otherwise the batteries overheat. If Tesla try to race in the cool air of winter then they dont have enoigh grip from the cold tyres.

As the batteries at the top of climb will be hot and the cruise power draw is still significant then the batteries will never cool down. During a traditional descent the batteries might cool down but you can just change the flight profile. Instead of having a gradual glide down at very low power the aircraft could continue at higher speeds and altitude for longer. The electric aircraft has the unique ability to make the engines windmill and recharge the batteries on descent. This process would cause significant drag and allow for the plane to descend very rapidly without overspeeding.


About batteries heating up.
If you discharge a 14Wh cell too fast that it heats up, you won't get 14Wh out of it but only 10Wh. The 4Wh will be lost in heat.
Alternatively you can put heaters to generate those 4Wh of heat.
Discharging fast shortens battery life too and is a major cause of premature failure.

Actually I deal in 18650's as part of what I do and I can' t count how many 18650's have failed prematurely. The Panasonic cells are the better ones, the failure rate is quite low compared to Samsung and LG ones. The irony is that despite selling these, I can't promote them as having the potential that some here clain. These batteries have flaws, perhaps you need to experience that first hand before you can see their limitations.
 
User avatar
Nomadd
Posts: 247
Joined: Sat Dec 09, 2017 3:26 pm

Re: Electric planes: the state of the art

Sat Dec 29, 2018 3:13 am

Nomadd wrote:
leghorn wrote:
Nomadd wrote:
So, you think you're going to get 19kwh more capacity for 15kg weight with a 250wh (usable) per kg battery?
Did you do the math for the million man march?

Why don't you go and search for details on the differences between a 22kWh and 41 kWh Renault Zoe before you try trolling me. Your belligerent approach to posting is unhelpful to discussion of the topic. Please attend to this.

So, supplying some very simple numbers is unhelpful, while your vague nonsense is helpful?
Do you have other numbers, is the Zoe magic or is the math too hard for you?
And by the way, trying to make insults acceptable by using polite language is the last resort of the incompetent.
 
Elementalism
Posts: 466
Joined: Sat Jun 10, 2017 4:03 am

Re: Electric planes: the state of the art

Sat Dec 29, 2018 6:00 am

frmrCapCadet wrote:
I am expecting the first commercial electric or hybrid plane to be flown earlier than most people think. I remember when Detroit was panning the early Prius - which cars are probably still being driven. BNSF/GE has already started building electric locomotives for use in LA. Our WA State ferry system has advanced plans for hybrid electric power for ferries.

Another important thing to keep in mind that electrification of transportation, residential, and industrial makes sense to do now. This sort of infrastructure lasts from a couple to several decades. As renewable energy becomes cheaper and more wide spread that carbon free energy will make that old infrastructure more carbon free.


I think it is a different market. Cars, at least right now are personal and not for profit. This may change if ride sharing replaces personal ownership of vehicles. Aircraft industry has a profit motive, at least in the airlines. And that is where it becomes a problem with todays technology. A 787 sized aircraft with a range of 1500nm like mentioned earlier in this thread is a non-starter with airlines.

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