Go Back  PPRuNe Forums > Flight Deck Forums > Rumours & News
Reload this Page >

Electric Powered Aircraft

Rumours & News Reporting Points that may affect our jobs or lives as professional pilots. Also, items that may be of interest to professional pilots.

Electric Powered Aircraft

Old 13th Apr 2019, 11:47
  #21 (permalink)  
 
Join Date: Sep 2005
Location: Post-Pit and Lovin' It.
Posts: 845
Originally Posted by msjh View Post
If you get 400 times less energy per kg, how do Teslas manage to work?
I believe this was covered nicely in post 12:

As of today, we produce electricity basically burning stuff. In cars, regen braking and all, you produce the same CO2 with an electric car than with a petrol one. They make a little sense because you take pollution away from city center.

But in planes, where wheels do not happily cancel the weight penalty at constant speed, the idea is crazy beyond belief. Completely derailed.
A Tesla is not a commercial vehicle whose purpose is to carry payload for profit. It only has to meet a (fairly small in comparison) payload threshold to carry it's driver, few passengers and a small bit of luggage.

And it absolutely does not "work" from an economic perspective, judging by Tesla's financials.

But it's a nice way to signal ones green virtue, if you have a hundred grand lying around. Just don't speak too loudly of the environmental horror that li-ion batts on that scale represent.
nolimitholdem is offline  
Old 13th Apr 2019, 12:10
  #22 (permalink)  
 
Join Date: Nov 2018
Location: madrid
Posts: 47
Originally Posted by msjh View Post
If you get 400 times less energy per kg, how do Teslas manage to work?
Because in cars, the penalty for overweight is zero at constant speed, and very little at variable speed if you compare with a solution without generative braking*.

Drag (the main reason you need energy to commute) is proportional to frontal area, which is not affected by how many kgs of "energy storage" you move about (in cars). Weight is cancelled "for free" by the wheels.

But in planes, weight is balanced with lift, and lift needs wings, and wings produce drag (proportionally). So every new kg of weight need either more wings or more AOA, both producing drag proportionally. In addition, more wings are also more kgs, in a non-linear way (think of the base of the eiffel tower), which contributes to the problem.

*Model S has 540 kgs of batteries, more or less equivalent to 1.35 kgs of fuel, 1.83L of diesel and a range of 400km. You can have a x3 because batteries are very good expensive Li-IO, x2 of electric vs thermal motor at ideal conditions and then an additional x2 due to generative braking (plus you get a bonus of almost ridiculous acceleration if you install the motors and electronics you need for powerful regenerative braking). So, in ideal conditions, it carries the equivalent of 22L of diesel fuel. My car (same size and weight) uses 6.0 l of diesel each 100 km, pure thermal, so there you have it: 400km. In ideal conditions. But there are reports of much much shorter trips depleting the batteries, as it is no surprise for me.
ecto1 is offline  
Old 13th Apr 2019, 12:20
  #23 (permalink)  
 
Join Date: Apr 2007
Location: EU
Posts: 28
The idea is to get cheaper rates for flight training. Nobody is talking about long range electric flight (yet).

Although someone is talking about electric VTOL supersonic flight already:


Just wait until he get's some time off from SpaceX, Tesla, The Boring Company and whatever else he is doing at the moment...
DRDR is offline  
Old 13th Apr 2019, 12:35
  #24 (permalink)  
 
Join Date: Jul 2013
Location: UK
Posts: 78
Originally Posted by ecto1 View Post
Because in cars, the penalty for overweight is zero at constant speed, and very little at variable speed if you compare with a solution without generative braking*.

Drag (the main reason you need energy to commute) is proportional to frontal area, which is not affected by how many kgs of "energy storage" you move about (in cars). Weight is cancelled "for free" by the wheels.

But in planes, weight is balanced with lift, and lift needs wings, and wings produce drag (proportionally). So every new kg of weight need either more wings or more AOA, both producing drag proportionally. In addition, more wings are also more kgs, in a non-linear way (think of the base of the eiffel tower), which contributes to the problem.

*Model S has 540 kgs of batteries, more or less equivalent to 1.35 kgs of fuel, 1.83L of diesel and a range of 400km. You can have a x3 because batteries are very good expensive Li-IO, x2 of electric vs thermal motor at ideal conditions and then an additional x2 due to generative braking (plus you get a bonus of almost ridiculous acceleration if you install the motors and electronics you need for powerful regenerative braking). So, in ideal conditions, it carries the equivalent of 22L of diesel fuel. My car (same size and weight) uses 6.0 l of diesel each 100 km, pure thermal, so there you have it: 400km. In ideal conditions. But there are reports of much much shorter trips depleting the batteries, as it is no surprise for me.
I'm afraid neither of these arguments convinces me (yet). But I am willing to learn!

I think for the compassion to work you need to compare
  • the weight of the fuel tank (and bits and pieces like fuel lines, exhaust system, etc) vs weight of the batteries
  • the weight of the petrol or diesel vs the "weight" of a charged battery vs depleted battery
I appreciate that in a plane you need the engines to produce enough power to generate lift, which is not needed in a car. But I think that 400x figure is substantially too high.

Three years ago, Forbes reported a study by scientists that Teslas (and EVs in general) produce substantially less pollution than ICE cars when all factors are taken into account.

(Incidentally, I photographed a small electric plane at Farnborough Air Show a few years back.
msjh is offline  
Old 13th Apr 2019, 13:02
  #25 (permalink)  
 
Join Date: Nov 2018
Location: madrid
Posts: 47
Originally Posted by msjh View Post
I'm afraid neither of these arguments convinces me (yet). But I am willing to learn!

I think for the compassion to work you need to compare
  • the weight of the fuel tank (and bits and pieces like fuel lines, exhaust system, etc) vs weight of the batteries
  • the weight of the petrol or diesel vs the "weight" of a charged battery vs depleted battery
I appreciate that in a plane you need the engines to produce enough power to generate lift, which is not needed in a car. But I think that 400x figure is substantially too high.

Three years ago, Forbes reported a study by scientists that Teslas (and EVs in general) produce substantially less pollution than ICE cars when all factors are taken into account.

(Incidentally, I photographed a small electric plane at Farnborough Air Show a few years back.
These are no arguments, these are facts, painfully learnt by me at work.

There are many more figures that go into the comparison, none of them changing the result.

For example, the weight of a foam filled fuel tank is usually 10% of the capacity, so for a cessna it would be about 12kg. Which equals the battery management system (BMS), roughly, for that power.

If i take into account the average weight of the system during a trip, a x1.5 is instantly granted to the thermal fuel, which you don't need to carry when you are almost empty.

In the advanced electric propulsion world, the figure you shoud use is x100 (x400 is fuel vs standard car battery, x2 / x3 electric motor efficiency vs thermal motor, x2 LI-IOn vs standar car battery). But do remember that if you use x100 you pay over 25000$ to have a equivalent energy storage capacity of 50L of fuel (vs the fuel tank itself at about 500$)

And remember the only reason that topping a battery is cheaper than topping a fuel tank is politics. It doesn't make any sense that the elaborated product (electricity) is cheaper than the base product (gas). In 2014, 66% of world electricity was generated burning stuff. Even if it were any difference in price, it would never ever be greater than x1.5 or something.

I wish electricity was actually cheaper, don't get me wrong, I wish a solar plant or aero generator wasn't so weak in terms of power / $. I hope this changes in the future. It may change.

But electric flight? short of battery technology breakthrough, no way.
ecto1 is offline  
Old 13th Apr 2019, 13:40
  #26 (permalink)  
 
Join Date: Nov 2018
Location: madrid
Posts: 47
By the way, that report previously posted:

https://www.ucsusa.org/sites/default...ull-report.pdf

Is flagrantly ignoring HUGE factors:

- The kwh/mi of the whole study are 0.333. TESLA model S and any other EV with some resemblance of range is is 0.38 (it is even recognized in the study). the 80mi range family of cars is another monster. apples vs apples please.
- The charging and discharging efficiency of the batteries is not even there anywhere! We are talking about 90% in both processes combined!

But the ovbious trick is to compare an average fuel powered car with an average EV. If you are concerned about CO2, you don't buy a supercharged V8.

The typical thermal car (full size gasoline) from the study emits about 350g CO2/km (+500/mi) during operation (see for yourself, figure 7, page21). Well, my 200+hp full size sedan (no hybrid) claims 121. I wonder were the rest comes from (they don't say)
ecto1 is offline  
Old 13th Apr 2019, 13:41
  #27 (permalink)  
 
Join Date: May 2003
Location: Canada
Posts: 99
Originally Posted by ecto1 View Post
- You cannot extract any energy from a battery if it is freezing.
This explains why electric cars have been outselling gas powered cars in Norway for the first time last month (first country in the world to do so). It is a well known fact that Norwegians are hibernating and do not need their car in the winter.

Originally Posted by ecto1 View Post
- After each cycle, battery stores less and less energy.
Not true for a well designed battery. See for example this heavy user of Tesla taxi fleet shows a Model X at over 300.000 miles with only 88% battery capacity degradation, and even better, no further battery degradation is observed beyond these initial 12%.
Model X 90D “Deuxy” Achieves 300,000 Miles In Less Than Two Years

The rest of your contribution to this thread is on par with the two items above - your belief is based on incorrect information. Maybe you should do a bit more research about electric cars in general and electric planes in particular. For short range applications, it is already reality today even if you do not want to accept it.
Machdiamond is online now  
Old 13th Apr 2019, 14:38
  #28 (permalink)  
 
Join Date: Jul 2009
Location: USA
Age: 74
Posts: 112
It is true that when a person states even one fact that is incredibly false - batteries produce no power when it is freezing - they lose all credibility in anything they say. I live where we have had many days with temps below -40 this winter, C or F, whichever you want to use. My vehicles outside will turn over by battery but will not fire off. Need electrical glow plugs, electrical coolant heaters, and fuel additives in order to go. Granted a battery loses power at the cold temps but at least it provides power while my petroleum engines need boosting. Sure it will take time for aviation to move to electric power but think of an electric motor turning the fan instead of the gas turbine that sporadically spews parts in all directions. Anyone buying hand power tools will realize that corded tools today are rare having been replaced with lithium ion battery powered tools, Recent offerings are chain saws and lawn mowers where one would assume battery weight would be an issue, but instead the reduced size electric motor and continually improved batteries have resulted in lightweight products without the reliability problems of the petroleum powered ones they replace. So maybe you won't be flying a electric powered A319, but I would never say never.
NWA SLF is offline  
Old 13th Apr 2019, 15:01
  #29 (permalink)  
 
Join Date: Nov 2014
Location: Moon
Posts: 13
There was an article this week on the BBC website regarding a German company that believe they have developed a battery that no longer relies on the heavy metals that are hard to source and that will give approx. 600 miles on a single charge. Estimate was for a production model within 5 years.

Technology is always getting better and I think an electric car in the mid 20s will outrun a Diesel engine with ease so an electric plane within 10-15 years should be feasible.

Haven’t EasyJet set themselves a target to fly an electric plane by 2028?
Reacher19 is offline  
Old 13th Apr 2019, 16:03
  #30 (permalink)  
Thread Starter
 
Join Date: Nov 2000
Location: Canada
Posts: 394
Electric Airplane on Salt Water

Top seaplane airline Harbour Air switching to battery-powered aircraft
Seaplane operator Harbour Air, which regularly shuttles B.C.'s political class to and from Victoria, is looking to become the first all-electric fleet of commercial planes in Canada – but the company head says passengers have nothing to fear.

Greg McDougall, founder of the company that bills itself as North America’s largest seaplane airline, said Monday that “I’ll be the first guy to fly one. I’ll be the test pilot of it.” He was referring to an electric-powered prototype the company will test within months as a prelude to electrifying the fleet within about two years.

By November, the company is planning to be testing a de Havilland Canada DHC 2 Beaver, a six-passenger aircraft equipped with an all-electric motor developed by magniX, a company based in Redmond, Wash. MagniX has been crafting the technology on the ground, but has yet to operate it in an aircraft.

“I wouldn’t put myself in there if I thought there was a problem. I certainly wouldn’t put my loved ones in there if I thought there was a problem – or my passengers," Mr. McDougall said.

“We have to prove a standard of safety that’s equal to or better than what we currently have.”

Mr. McDougall, who founded Harbour Air in 1982 with a pair of small seaplanes, says he is making the shift to keep ahead of the electrification of transportation, and also to reduce the company’s environmental impact.

He said his company is in a unique position to advance the concept of electric flight because its flights are relatively short, with average lengths of about 30 minutes in single-engine aircraft that don’t require as much power or battery capacity as other aircraft.

The company also has flights to and from destinations such as Nanaimo, B.C., and Tofino, B.C., on Vancouver Island as well as Whistler, B.C., , Sechelt, B.C., and Salt Spring Island, B.C., among other locations. They carry about 500,000 passengers a year.

Steve Holding, chief instructor for aviation technical programs at the British Columbia Institute of Technology, said electric flight is being developed but without breakthroughs on the scale Harbour Air is proposing.

“Powering a larger aircraft with batteries is still really a huge technical challenge just because of the weight of batteries required to put out the power to allow a larger aircraft to take off and climb – one I wish we could overcome as quickly as possible,” he said.Roei Ganzarski, chief executive of magniX, agreed on the battery issue. “Battery density is not where we want it to be for long-range flying, similar to where automobiles were seven years ago,” he said in an interview.

However, he said the company has been working on the technology, and electric makes sense for Harbour Air, which would not have to significantly change their operations for electric flight.

Asked about whether he had ever heard of an airline anywhere executing the idea, Mr. Holding referred to a media report from late 2018 about an airline using small aircraft in the Orkney Islands, an archipelago off Scotland’s northeastern coast, looking at the idea.

Like Alberta and Quebec, British Columbia’s legislature is not in the province’s largest city. While Vancouver is B.C’s urban centre, the legislature, and key offices of the civil service, are in Victoria more than 100 kilometres south across the Georgia Strait. That creates a need for movement between the two cities that is met by the ferries, commercial helicopter flights, and by Harbour Air.

The airline, which has a fleet of about 40 aircraft, will eventually face a path of approval from Transport Canada and the U.S. Federal Aviation Agency – flights to and from Seattle are among the dozen routes it offers.

Mr. McDougall said the company has already been in touch with regulators in both countries.
He said this shift is not a whim, but a mandate he handed to his executive team. It took off when he made a connection with magniX.
“We were already on the pathway of trying to figure this out and then we met the magniX people, who had a common code with us, which was to pioneer this. They obviously have a commercial reason for doing that,” he said.
https://www.magnix.aero/products/

Longtimer is offline  
Old 13th Apr 2019, 17:27
  #31 (permalink)  
 
Join Date: Apr 2008
Location: on the ground
Posts: 262
Originally Posted by ecto1 View Post
Gas has 46.4Mj/kg.
Except that the former is ideal conditions and the latter is always. Usual problems nobody tells you until it's too late:
How do you propose to extract 46.4Mj of shaft power (not just heat) from a kilogram of petrol?

The latter isn't "always"; it's not even "ideal conditions". You *might* get about half that, more likely 25% to 40%.
nonsense is offline  
Old 13th Apr 2019, 18:30
  #32 (permalink)  
 
Join Date: Nov 2002
Location: Northern Europe
Age: 41
Posts: 134
Originally Posted by Wizofoz View Post
….Except the e-flyer exists and has flown- the amphibian is just one more "paper aeroplane",
The "paper aeroplane" flew last summer...
The Bartender is offline  
Old 13th Apr 2019, 18:55
  #33 (permalink)  
 
Join Date: Nov 2002
Location: Northern Europe
Age: 41
Posts: 134
Originally Posted by ecto1 View Post
Yeah, dream all you want. BTDT. When you have 400 times less energy per kg, all things considered, no amount of politics will make it a viable alternative for airborne trasport. Period.
How does the efficiency of gasturbine vs. electric motor affect the amount of energy required?

Tesla claims an efficiency over 90%, while a gas turbine may perhaps reach the 30's?
Toyota made a big deal of it when making a gasoline engine reach 38% efficiency...
The Bartender is offline  
Old 13th Apr 2019, 19:17
  #34 (permalink)  
 
Join Date: Nov 2000
Location: UK
Age: 64
Posts: 1,053
There seems to be an enormous amount of ignorance about thermodynamics and chemistry displayed on this thread. Ecto 1 may not be the most diplomatic of contributors but he has a good grasp of the science and engineering, as does Elon Musk but he is also a great salesman from whom I would not buy a used car.

If you are so concerned about global warming and CO2 levels, don't travel.
beardy is offline  
Old 13th Apr 2019, 19:25
  #35 (permalink)  
 
Join Date: Sep 2005
Location: Post-Pit and Lovin' It.
Posts: 845
I'm not sure why ecto1 bothers. There is more wishful ideology than science being expressed. That becomes obvious when you see attempts to equate battery-powered cars and power tools to airplanes.

Fossil fuels have a net calorific value roughly 100 times of a manganese type lithium-ion battery. Thus an internal combustion engine at 38%, even at a low efficiency of 25%, vastly outperforms the best battery in terms of energy-to-weight ratio. The capacity of a battery would need to increase twenty-fold before it could compete head-to-head with fossil fuel. (A kerosene-powered turbine is even more efficient than an ICE, power-to-weight).

Tesla's claimed efficiency is for the power produced, not the power stored, which seems to confuse people. Fossil fuelled engines ARE less efficient than electric motors, but when the fuel source is still many multiples higher in NCV than the batteries necessary to store electricity they're going to be the only economically viable choice for weight-critical applications unless the battery tech improves exponentially.
nolimitholdem is offline  
Old 14th Apr 2019, 08:27
  #36 (permalink)  
 
Join Date: Nov 2002
Location: Northern Europe
Age: 41
Posts: 134
Originally Posted by nolimitholdem View Post
The capacity of a battery would need to increase twenty-fold before it could compete head-to-head with fossil fuel. (A kerosene-powered turbine is even more efficient than an ICE, power-to-weight).
A battery-powered vehicle will probably never be able to truly compete with ICE, but at some point ICE will be either out of fuel or simply banned.
In the mean time everybody should be happy somebody bothers to research alternatives and try new applications for our current level of technology.
The Bartender is offline  
Old 14th Apr 2019, 14:03
  #37 (permalink)  
 
Join Date: Feb 2008
Location: London
Posts: 6
Until battery capacity/weights get better, I would have thought a hybrid is the better way to go - the power supply to the prop could be drawn on a rotational basis between the six banks of batteries, with 3 banks , at any one time, being on charge from a highly tuned lightweight Hydro carbon burning turbine. According to the wiki page below, they are already available with a a power output of 73Kw and weight of 55Kgs and a fuel consumption similar to a normal petrol engine. I would have thought that that level of electrical output would easily support running 3 of the battery banks (3 x 15 Kwh) on charge at any one time whilst the other 3 banks (45Kwh available) supplied the prop. So, assuming the batteries would accept that level of charge, you could re-charge three banks of batteries in 37 minutes. Plus you'd get the extra thrust from the turbine exhaust when the generator was on. Even with a 4 gallon tank of propane or similar, wouldn't that double the endurance ?

And the availability of a microturbine might mitigate the effects of loss of battery capacity in cold weather.

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

N
NAROBS is offline  
Old 14th Apr 2019, 15:20
  #38 (permalink)  
 
Join Date: Nov 2005
Location: UK
Age: 73
Posts: 231
As can be seen from all the comments the problems is the storage of electrons and the energy to weight factor.
Avgas has about 11 kw per kilo but IC engines at 25% efficient so can only extract about 3 kw/kilo. Electric motors are up at 90+% so only need a battery of 2.5 to 3.5 kw/kilo to match Avgas. Lithium has a theoretical energy density of about 10kilowatts/kilo. At the moment the best lithium batteries are around 500 watts/kilo so 5 five times the weight for the same amount of Avgas. Billions of dollars are being spent on battery research so higher densities are coming. The holy grail is lithium air batteries, these should meet or exceed the 2.5kw/kilo target to make liquid fuels obsolete. A US university has an experimental Lithium air that is looking good, time will tell. In the last ten years the cost of EV batteries have dropped by a factor of ten to about 175 dollars per Kilowatt and heading towards $100 per Kw which makes the manufacture of EVs the same as an IC vehicles, plus the density has doubled and will keep increasing. So for aircraft at the moment batteries are not a total replacement solution but a 2 hour endurance is just feasible, which would be good for training. A hybrid is the best solution at the moment it has so many good points a high speed high power density IC engine gas or diesel with no gear box or harmonic problems. Props can be located almost any place on the airframe. So electric drive is compelling and I think will be more reliable and cost less to operate in the future.
horizon flyer is offline  
Old 14th Apr 2019, 15:25
  #39 (permalink)  
 
Join Date: Mar 2005
Location: Poplar Grove, IL, USA
Age: 53
Posts: 843
United Technologies is working on a hybrid electric aircraft.
https://www.utc.com/en/news/2019/03/28/project-804
Their demonstrator is a Bombardier Dash 8, not a part 23 Cessna.
IFMU is online now  
Old 14th Apr 2019, 17:04
  #40 (permalink)  
 
Join Date: Apr 2008
Location: on the ground
Posts: 262
Originally Posted by horizon flyer View Post
Avgas has about 11 kw per kilo...
Do you mean kilowatt hours? Or perhaps kilojoules? Because kilowatts per kg makes no sense at all.
nonsense is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information

Copyright © 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.