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Electric Powered Aircraft

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Electric Powered Aircraft

Old 5th Aug 2019, 17:59
  #121 (permalink)  
 
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Originally Posted by Less Hair
The main problem for battery powered aircraft I see is their weight. Especially on landing. An empty battery is as heavy as a fully loaded one. That's like every landing will be a heavy landing. Combine that with short endurance and many short flights and you have a high structural fatigue and you will need more robust structure.
Yes, but at what point does landing weight become a special factor? I.E. must be a value less than MTOW, and so-listed in the manual? And assumed by the engineers? And does that include any aircraft likely to be electrified any time soon?

If a given design has a MLW of 5000kg, it can land at 5000kg. That is the spec, and it can be landed that way on every landing. There's nothing in the books that says "MLW - but only use this 10% of the time!"

And it doesn't matter how that weight is divided between structure, engines, batteries/fuel, and payload. Payload being the factor where adjustments are most easily made.

The difference between MTOW and MLW for a Twin Otter is 200lb/90Kg. Leave out one seat = end of problem.

Of course, that doesn't contradict the general idea that weight is always a critical problem in any aircraft, from balloons to A380s. And that electric flight beyond a certain point will depend on "unrealized" technology, like the ability to make aluminum engine blocks in place of cast-iron was for aviation 116 years ago.

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Old 5th Aug 2019, 21:05
  #122 (permalink)  
 
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Originally Posted by pattern_is_full
Yes, but at what point does landing weight become a special factor? I.E. must be a value less than MTOW, and so-listed in the manual? And assumed by the engineers? And does that include any aircraft likely to be electrified any time soon?

If a given design has a MLW of 5000kg, it can land at 5000kg. That is the spec, and it can be landed that way on every landing. There's nothing in the books that says "MLW - but only use this 10% of the time!"

And it doesn't matter how that weight is divided between structure, engines, batteries/fuel, and payload. Payload being the factor where adjustments are most easily made.

The difference between MTOW and MLW for a Twin Otter is 200lb/90Kg. Leave out one seat = end of problem.

Of course, that doesn't contradict the general idea that weight is always a critical problem in any aircraft, from balloons to A380s. And that electric flight beyond a certain point will depend on "unrealized" technology, like the ability to make aluminum engine blocks in place of cast-iron was for aviation 116 years ago.
Based on current power densities, a 90 Kg battery will provide enough power to support a Twin Otter for three or four minutes.

Using electric power to substitute for two GE90-110 engines will require a battery weighing more than the passengers and fuel that a 773 can carry.

The entire idea of electrifying airplanes is rather pointless. The pretzel twists of different methods being proposed by the acolytes to attain what is essentially insignificant flight time illustrates that quite easily.

Last edited by ThreeThreeMike; 6th Aug 2019 at 00:30.
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Old 5th Aug 2019, 21:27
  #123 (permalink)  
 
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Originally Posted by pattern_is_full
Yes, but at what point does landing weight become a special factor? I.E. must be a value less than MTOW, and so-listed in the manual? And assumed by the engineers? And does that include any aircraft likely to be electrified any time soon?

If a given design has a MLW of 5000kg, it can land at 5000kg. That is the spec, and it can be landed that way on every landing. There's nothing in the books that says "MLW - but only use this 10% of the time!"

And it doesn't matter how that weight is divided between structure, engines, batteries/fuel, and payload. Payload being the factor where adjustments are most easily made.

The difference between MTOW and MLW for a Twin Otter is 200lb/90Kg. Leave out one seat = end of problem.

Of course, that doesn't contradict the general idea that weight is always a critical problem in any aircraft, from balloons to A380s. And that electric flight beyond a certain point will depend on "unrealized" technology, like the ability to make aluminum engine blocks in place of cast-iron was for aviation 116 years ago.
You omit the fact that with a fuel verses electric aircraft you can adjust the amount of energy you carry onboard to account for the length of flight and other variables. A electric aircraft loses the ability to depart with a 50% fuel load to allow increased payload. In airline operations that occurs on almost every flight. A twin otter with a OEW of about 8000 lbs would be heavily load restricted if it took off with fuel fuel every flight. Payload would be about 2000 lbs max. Perhaps 9 passengers and baggage. Batteries are going to need to be far lighter than a comparable fuel load before the concept becomes viable. The same energy density would result in many operational restrictions.
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Old 6th Aug 2019, 06:50
  #124 (permalink)  
 
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the only electrically powered transport that really makes sense is railways. Effectively a direct link from power station to motive power unit. No energy storage required.

A downside that never gets mentioned for battery vehicles, that would surely be another nail in the aircraft coffin is the weight doesn't go down with usage, so landing weight would be same as take off, and you're always lugging around partially useless batteries, as opposed to air in an emptying fuel tank.

For aviation, electric tugs or an equivilant to save fuel burn on taxi would make sense, if you don't have to get things up to temp of course.
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Old 6th Aug 2019, 23:31
  #125 (permalink)  
 
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Danger

Where are they going to park these electric aircraft whilst the batteries are on charge?
Not very profitable for airlines to have planes on the ground with extended turn around times.
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Old 7th Aug 2019, 00:24
  #126 (permalink)  
 
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Originally Posted by Bravo Delta
Where are they going to park these electric aircraft whilst the batteries are on charge?
Not very profitable for airlines to have planes on the ground with extended turn around times.
With current battery technology (Porsche 350 kW fast chargers and Tesla SuperChargers), about 30 minutes at the gate. In five years from now, about 20 minutes which is typical short haul turnaround time.

Thanks for asking.
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Old 7th Aug 2019, 00:33
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Originally Posted by ThreeThreeMike
Based on current power densities, a 90 Kg battery will provide enough power to support a Twin Otter for three or four minutes.
You are a bit off and misunderstood the point Pattern_is_full was making. The MagniX - Harbour Air retrofit of the Beaver with electric power is pretty much based on the PT6 STC and 6000 lb increased gross weight, which allows for 40 minutes endurance with 6 passengers with a 600 - 700 kg battery and still within the STC weights. Harbour Air typically does 15 minutes hops with their Beavers so the numbers check out ok in my book.
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Old 7th Aug 2019, 00:40
  #128 (permalink)  
 
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Originally Posted by Sailvi767
You omit the fact that with a fuel verses electric aircraft you can adjust the amount of energy you carry onboard to account for the length of flight and other variables. A electric aircraft loses the ability to depart with a 50% fuel load to allow increased payload. In airline operations that occurs on almost every flight.
You omit the fact that electric aircraft is only viable with (and serious electric projects only claim) really short range routes, like inter island below 100 nm. In these conditions, relative to conventional aircraft, you operate well below fuel with maximum payload so you never worry about these trades. You fuel up for short range and you go with max payload all the way, like the ATR's.
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Old 7th Aug 2019, 00:48
  #129 (permalink)  
 
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Originally Posted by Less Hair
The main problem for battery powered aircraft I see is their weight. Especially on landing. An empty battery is as heavy as a fully loaded one. That's like every landing will be a heavy landing. Combine that with short endurance and many short flights and you have a high structural fatigue and you will need more robust structure.
It might be a challenge for the electrification of an existing design but not such a big deal if you give up some payload as pattern_is_full pointed out.

For a clean sheet design, the empty weight penalty of bringing structural weight from MLW to MTOW is about 0.7% (actual number of one hybrid design I am working on). In the list of main problems for battery powered aircraft, that landing weight issue ranks below the top 100.
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Old 7th Aug 2019, 01:35
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Originally Posted by Machdiamond
With current battery technology (Porsche 350 kW fast chargers and Tesla SuperChargers), about 30 minutes at the gate. In five years from now, about 20 minutes which is typical short haul turnaround time.

Thanks for asking.
Not even a remotely valid comparison. The amount of energy transfer needed is going to be vastly greater than charging a car. Cable sizing alone is going to be interesting!
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Old 7th Aug 2019, 02:05
  #131 (permalink)  
 
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Originally Posted by Sailvi767
Not even a remotely valid comparison. The amount of energy transfer needed is going to be vastly greater than charging a car. Cable sizing alone is going to be interesting!
For short haul on 6-9 passenger all-electric aircraft is about a factor of five for small commuters, ten at most (500 kWh to 1 MWh). This is about the same level of electric truck charging infrastructure currently in development. Google HPCCV and such.

You may be thinking about larger aircraft but that is not what I am talking about.
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Old 7th Aug 2019, 03:35
  #132 (permalink)  
 
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Originally Posted by Machdiamond
For short haul on 6-9 passenger all-electric aircraft is about a factor of five for small commuters, ten at most (500 kWh to 1 MWh). This is about the same level of electric truck charging infrastructure currently in development. Google HPCCV and such.

You may be thinking about larger aircraft but that is not what I am talking about.

the trend with electric air trainers is for the battery to be modular and swap-able "(2 to 5 minutes)" turnaround one pack charging on the ground another in the air. agree we arn't talking a380 yet but for short hops and training flights this technology is real and current.

https://electrek.co/2018/04/27/all-e...cation-faa-us/
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Old 7th Aug 2019, 04:30
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This is what is commonly called a con. Anyone in the know can hand around press releases saying any damn thing, but that doesn't make it true. You'd have to verify every element of the story to know the whole truth the PR won't mention.

The whole basis of switching to electric vehicles is based on the lie that CO2 from fossil fuels cause climate change, and the true irony is that oil isn't a fossil fuel, CO2 is good for the planet, and climate change is natural. There's a lot more to it than this, but I don't want to bore you with the details, because there are a lot.
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Old 7th Aug 2019, 06:18
  #134 (permalink)  
 
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Originally Posted by Manwell
There's a lot more to it than this, but I don't want to bore you with the details
Much appreciated.

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Old 7th Aug 2019, 08:46
  #135 (permalink)  
 
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Originally Posted by Manwell
The whole basis of switching to electric vehicles is based on the lie that CO2 from fossil fuels cause climate change, and the true irony is that oil isn't a fossil fuel, CO2 is good for the planet, and climate change is natural. There's a lot more to it than this, but I don't want to bore you with the details, because there are a lot.
CO2 may be good for your planet, but on our planet we have rather too much of it in the atmosphere.

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Old 7th Aug 2019, 11:21
  #136 (permalink)  
 
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and the true irony is that oil isn't a fossil fuel
Let me guess, it was created six thousand years ago?
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Old 7th Aug 2019, 11:40
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Charging speeds are already at 10.5MW for battery-powered Ferries. Itís all done with a robotic connector, too, no refueller required.

https://www.forseaferries.com/about-...ustainability/
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Old 7th Aug 2019, 11:59
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Originally Posted by Machdiamond
You omit the fact that electric aircraft is only viable with (and serious electric projects only claim) really short range routes, like inter island below 100 nm. In these conditions, relative to conventional aircraft, you operate well below fuel with maximum payload so you never worry about these trades. You fuel up for short range and you go with max payload all the way, like the ATR's.
It will be impossible to build or convert a aircraft at a reasonable cost with such a limited utility. No one will want it and shipping it anywhere will be a pain. For a electric to be successful it needs to have a market that makes it commercially viable. A 100 mile range wonít achieve that.
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Old 7th Aug 2019, 13:20
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Originally Posted by Sailvi767
It will be impossible to build or convert a aircraft at a reasonable cost with such a limited utility. No one will want it and shipping it anywhere will be a pain. For a electric to be successful it needs to have a market that makes it commercially viable. A 100 mile range wonít achieve that.
What percentage of Cape Air routes are under 100 miles? How do you think they will like near zero maintenance cost on the propulsion system and cheap electric recharge at a small fraction of the fuel cost? Isn't that also going to make more routes commercially viable?

What about the competitiveness of an emissions free aircraft servicing cities that are progressively banning internal combustion engine cars (mostly in Europe for now)? Once such an aircraft becomes available, are those cities going to expand that mandate to airplanes of that size?

All-electric small regional aircraft is a small aircraft / small distances marke, and being all-electric changes the economics of the operations quite a bit.

For longer ranges, there is hybrid propulsion. Up to 600 nm range maybe. Further than that the fuel saving gets cancelled out by the weight of the system, with today's battery energy density. So it will be a long while before we see all-electric Boeings and Airbus.


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Old 14th Aug 2019, 13:50
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First el-craft crash in Norway today. Both occupants survived. No more details at present.
Edit. Not a crash, successful emergency landing. Avinor boss was pilot.
New edit. If you land on your nose, in water it is apparently considered an emergency landing.
https://www.dagbladet.no/nyheter/elf...-bord/71491030
Per

Last edited by Ancient Mariner; 14th Aug 2019 at 16:11.
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