[libranof1987]

An electric airplane! Wouldn't that be something!

As ridiculous as this may sound at the moment, it clearly can't be dismissed.

Advancements in science, fueled by an overall worry about the harm caused to the planet by fossil fuels, have given rise to ground-breaking solutions.

One of them seems to be an electric airplane.

EasyJet, a popular no-frills budget airline in Europe, is now looking at having electric airplanes in their fleet within the next decade!

Major European carrier EasyJet announced Wednesday that it is teaming up with U.S. startup Wright Electric to build an all-electric airliner.

The aircraft they have in mind would handle short routes of 335 miles or less -- think New York to Boston or London to Paris.

Wright Electric was founded in 2016 by a team of battery chemists, aerospace engineers and electric vehicle experts from NASA, Boeing (BA) and Cessna.

It received funding from Harvard University and startup incubator Y Combinator, which helped fund Dropbox, Reddit and Airbnb. EasyJet did not reveal the financial terms of its partnership with the startup.

http://money.cnn.com/2017/09/27/tech...ght/index.html

EDIT: Another interesting read is the Solar Impulse journey: two pilots took turns to circumvent the earth in a solar-powered plane

http://www.solarimpulse.com/adventure

[abhishek46]

Some enlightened one, once told me that in aviation and rockets, the number one priority is the thrust to weight ratio.
A jet plane, takes off heavy (with loads of power dense jet fuel), but lands light. Burning off fuel mid way reduces the load to a great extent, and results in a much better overall fuel burn rate.

In electrics, the weight of the plane will remain constant (i.e. heavy). Due to this factor alone, the economics of running one is questionable.

Secondly, a turbo prop/jet can be fully refueled in less than an hour, whereas to charge mammoth batteries of an electric plane can take much longer.

Lastly, in case of electric planes, good amount of heat will be generated by batteries during charging and discharging. Boeing had a tough time controlling heat in a rather small Li-ion battery pack. Imagine the issues in a massive plane sized battery pack.

[libranof1987]

^^ Fair points.

I believe there'll be solution to most of the points raised except one: time taken to charge.

These days, economics demand that planes are in the air as much as possible. Airliners would not want their planes sitting idle when they could be earning revenue.

But who knows; scientists might just pull a rabbit.

Skepticism (justified to some extent) aside, there are very few (scientific) possibilities that we can disregard these days.

EDIT:

Originally Posted by narayan

While I am overall skeptical, on the charging part, why should one think of a plane having to be hooked up to a power supply and be charged ? Why not, the exhausted battery pack be removed and fitted with a fully charged one at the airport while the removed one gets charged for the next flight ?

Precisely what I was thinking.

[narayan]

While I am overall skeptical, on the charging part, why should one think of a plane having to be hooked up to a power supply and be charged ? Why not, the exhausted battery pack be removed and fitted with a fully charged one at the airport while the removed one gets charged for the next flight ?

[srishiva]

I think the battery pack will be swapped like they do with baggage. Cooling should not be an issue if you expose the heat sinks outside in the cool outside air at high altitutes.
They might have better solutions already !

[ksameer1234]

Just did a quick search and energy density for aviation fuel comes around 43 MJ/kg while that for Li-Ion battery is less than 1 MJ/kg. Supercapacitors fare far worse. In aviation where weight is such an important parameter, I wonder how it will be justifiable to use such poor density energy source.

[V.Narayan]

Originally Posted by libranof1987

An electric airplane! Wouldn't that be something!
As ridiculous as this may sound at the moment, it clearly can't be dismissed.

Thank you @libranof1987. Electric power and air craft are two things I find most interesting. A combination cannot keep me from posting!

For all the skeptics out there we should not assume we can predict what technology will bring in 40 years. In 1905 no one but no one could have imagined that the atom will be split and bombs dropped in 1945. In 1929 no one could have believed that man would walk on the moon 40 years later. And in 1960 no one could have conceived of the world wide web and realized how it would change the way we communicate and socialize. So never say never.

Now onto the aeronautical part. An aircraft flies because of three things - first the wings and their efficiency, second the engines and their efficiency and third the power to weight ratio. Advances in wing design, wing weight, engine and airframe weight and of course energy density of the power source all could converge eventually to make practical applications of various aircraft even if they don't come to large commercial liners soon enough. Who knows what break through in fuel cells will come in the next 35 years.

In 1931 the concept of a jet engine was only an idea in the heads of Sir Frank Whittle and the German Prof Hans Von Ohain. Both derided by their own military, government and aeronautical industry. Yet in 1961 the Boeing 707 and Douglas DC-8 were criss-crossing the Atlantic carrying lakhs of passengers a year.

Photo below of the Airbus E-Fan plane an experimental concept proving aircraft built by Airbus. I saw its flight when it was demonstrated at Farnborough, UK in 2014. Airbus, Siemens and Rolls Royce are working together to invent tomorrow's low carbon footprint technology in aviation. Will a passenger electric-airliner fly by 2027 ...hard to say. will it be in service by 2037...a reasonable probability.

Never say never.

photo source Wikipedia

[Jeroen]

I think it’s an interesting development. The charging times are reduced quite rapidly, maybe swapping batteries as suggested would be an option as well.

But the biggest challenge remain the weight to power ratio. That has been steadily getting better during the last decade as well. They aim to use this electric plane on short routes only so weight reduction during flight (e.g. like burning off fuel) is not relevant.

Obviously the weight of the battery would always be a concern. Never the less I would imagine that a lot of other components on an e-plane are likely to be weighing a lot less compared to the jet plane. E.g. E-motor weighs less than a jet engine, no fuel pumps/valves/plumbing.

If you replace the various hydraulic systems for e-system that could save a lot of weight too. (no hydraulic pumps, motors, piping, tanks/liquid etc)

Obviously an e-plane will look like a plane. It flies based on the same laws of physics as any plane. But I would expect that from an engineering/design point of view it would be very different than any other plane.

Which also means that everything requires a very lengthy and costly certification process.

Still, interesting development and I’m convinced we will see commercial e-plane in the not so distant future. Mind you, I’m not holding my breath yet!

Jeroen

[volkman10]

Airbus is getting into the flying electric taxi fray

Still in engineering and prototype build stages, the CityAirbus envisions an electrically powered four-passenger craft meant for short flights -- from an airport on the outskirts of a major city to a city center, for instance -- powered by 100-kW Siemens electric motors for lift and for forward flight, drawing juice from a 140-kWh battery. The quad-fairing design uses a total of eight propellers and promises a much lower acoustic footprint, according to Airbus, in addition to greater safety and stability

link

[Rahul Bhalgat]

Originally Posted by Jeroen

But the biggest challenge remain the weight to power ratio. That has been steadily getting better during the last decade as well. They aim to use this electric plane on short routes only so weight reduction during flight (e.g. like burning off fuel) is not relevant.

Originally Posted by ksameer1234

Just did a quick search and energy density for aviation fuel comes around 43 MJ/kg while that for Li-Ion battery is less than 1 MJ/kg. Supercapacitors fare far worse. In aviation where weight is such an important parameter, I wonder how it will be justifiable to use such poor density energy source.

I agree with V. Narayan, Jeroen, ksameer and others about the present limitations of power to weight ratios for the batteries that will reduce the payloads drastically.

One application that permits low payloads and relatively high charging time is UAV (drones). Hence the drones running on battery power are in use.

Originally Posted by V.Narayan

Who knows what break through in fuel cells will come in the next 35 years.

Will a passenger electric-airliner fly by 2027 ...hard to say. will it be in service by 2037...a reasonable probability.

Never say never.

[apachelongbow]

Regarding weight, do you know what a turbofan engine weights? A single IAE highbypass turbo fan engine of airbus 320 weighs a whopping 5 tons, that too without oils and fluids. Out off a total empty weight of 37 tons in a 320, 10 tons come from engines alone. A battery pack will not be heavier than 10 tons even for heavy load applications.
The major problem is redundancy. Modern airplanes operate on pneumatic, hydraulic and electrical systems often having triple backups. With an electric motor, it will use all energy to produce thrust. If it produces pneumatic and hydraulic power as well, it cant have enough thrust or range to operate.

The only reason aeroplanes became so large and mainstream was due to their jet engines. Only piston power or even turboprop would never give the range or volumes to make air travel do cheap or popular. In theory when the world moves to renewable energy sources and cars run on batteries, oil will be dirt cheap to power airplanes

[Rahul Bhalgat]

Originally Posted by ksameer1234

and energy density for aviation fuel comes around 43 MJ/kg while that for Li-Ion battery is less than 1 MJ/kg.

Originally Posted by apachelongbow

A single IAE highbypass turbo fan engine of airbus 320 weighs a whopping 5 tons, that too without oils and fluids. Out off a total empty weight of 37 tons in a 320, 10 tons come from engines alone. A battery pack will not be heavier than 10 tons even for heavy load applications.
The major problem is redundancy. Modern airplanes operate on pneumatic, hydraulic and electrical systems often having triple backups. With an electric motor, it will use all energy to produce thrust. If it produces pneumatic and hydraulic power as well, it cant have enough thrust or range to operate.

The only reason aeroplanes became so large and mainstream was due to their jet engines. Only piston power or even turboprop would never give the range or volumes to make air travel do cheap or popular. In theory when the world moves to renewable energy sources and cars run on batteries, oil will be dirt cheap to power airplanes

Appreciate the vital point that you raised; jet engine is the better alternative to produce thrust compared to motor-fan arrangement. It directly produces thrust unlike the motor-propeller combo which first produces torque and then translates it to thrust.

Range of jet engine can be equalled by motor-propeller combo with more batteries. This means reduced payload, considering the energy density of the battery technologies. And hence higher cost of travel / freight as you said.

To operate the hydraulic and pneumatic systems, we can have separate electric motors (driving the compressors and hydraulic pumps). These again need to be powered by batteries. So it again comes to the fact the fossil fuel offers maximum energy density.

[Jeroen]

Originally Posted by Rahul Bhalgat

Appreciate the vital point that you raised; jet engine is the better alternative to produce thrust compared to motor-fan arrangement. It directly produces thrust unlike the motor-propeller combo which first produces torque and then translates it to thrust.



Range of jet engine can be equalled by motor-propeller combo with more batteries. This means reduced payload, considering the energy density of the battery technologies. And hence higher cost of travel / freight as you said.



To operate the hydraulic and pneumatic systems, we can have separate electric motors (driving the compressors and hydraulic pumps). These again need to be powered by batteries. So it again comes to the fact the fossil fuel offers maximum energy density.

You cant compare jet engines to motor fan or turbo fans on thrust alone. Its all about trade offs on thrust, fuel efficiency, max payload etc. that why we still see two engine turbo props. They have another advantage over the jet engines. The prop wash over the wings helps develop additional lift resulting in shorter
.

I don't see any merits powering hydraulic system with emotors. Just replace all hydraulic system with 100% electric one. It would save a lot of weight, increase reliability, less maintenance etc. similar to what is happening in the car industry .

We used to have hydraulic power steering, now nearly all new cars have electrical power steering. That's not a hydraulic system driven by an e-motor, but a completely different system.

I would say the certification of such an eplane and all of its electrical systems is going to be a huge challenge. It's so far removed from the current way.

The current Tesla 85kwh battery pack weighs in at a hefty 540kg. So for swapping one current jet engine of 5 tonnes we can install 9 Tesla battery packs (weight wise) or 18 for two jet enigne. Which equates to 1530Kwh.

I don't think that is going to get any commercial viable plane into the air. If you read up on the technical analyses around these E-plane it comes down to two things:

Vastly improved batteries in terms of capacity over weight and volume
Certification

On the first one we have seen an accelerated development, question remains will this continue to accelerate, start bottoming out?

On the second one, nobody can really tell, partly because there are no current certification rules pertaining to E-planes.

Jeroen

Jeroen

[sgiitk]

At the moment it looks more like a publicity gimmick, since electric powered planes are unlikely to have the load / range capabilities. Of course things may change in as little as five years.

[apachelongbow]

A couple of things first. Current technology electric motors cannot power heavy load users like flaps, slats or landing gears. At best it can work compressors for pressurization and air-conditioning (like the 787). In a medium jetliner like a 320, the hydraulic pressures used are about 3000 psi to operate flaps and landing gears, an electric motor heavy enough to operate on these forces will be large, heavy and draw current which batteries may not supply. Although in smaller airplanes like a Cessna or a diamond all the operations are electric powered only, mainly in the interest of weight savings.
I agree that current battery technology is not mature enough to supply commercial aircraft, its not mature enough to power a mass electric car even. The day batteries offer energy density and efficiency equivalent to a petrol engine, there may be applications to flight as well.
Regarding turbo prop aircraft, they have major problems regarding useful payload, range and most important of all, speeds. A turboprop is restricted to mid mach numbers due preventing propeller tip over-speeding into mach regimes. Hence for long distance commercial flights, a turbofan (jet) is the only way forward.
As is a turbofan or a turboprop is incredibly efficient and environmentally friendly. Consider this: An atr 72 airplane carries 70 passengers plus cargo at speeds of 200 kts (370 kmph) burning 600 kgs (both engines per hour). Compare this with cost of fuel per passenger for a 4 seater car traveling at 100kmph, averaging 12kmpl for 4 hours (to cover the same 370km). Likewise an airbus 320 burns 2400kgs per hour traveling 850kms with 180 passengers and 15 tons of cargo.
Currently airplanes are most fuel efficient technology, there after there are railways and lastly personal cars and bikes. The only way to save fuel and reduce emissions is to either ban personal cars or make them all electric or renewable energy driven.