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Hefaistos

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Re: Aviation
« Reply #50 on: March 17, 2017, 07:56:49 PM »

A new study from NASA has shown that the jet engines using biofuels have fewer particle emissions in their exhaust trails.
"As a result, the observed particle reductions we've measured during ACCESS should directly translate into reduced ice crystal concentrations in contrails, which in turn should help minimize their impact on Earth's environment,"
http://www.cnbc.com/2017/03/17/biofuels-cut-jet-engine-pollution-nasa-study-shows.html

I believe that aviation over the Arctic ocean contributes to the creation of polar stratospheric clouds. These contribute to the warming over the Arctic, according to a research paper previously reported on the forum.
Scientists recently discovered that polar stratospheric clouds, long known to play an important role in Antarctic ozone destruction, are occurring with increasing frequency in the Arctic. The PSCs have been frequently seen in northern parts of Scandinavia during this winter, according to various reports.
http://earthsky.org/earth/wow-polar-stratospheric-clouds


Hefaistos

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Re: Aviation
« Reply #51 on: March 17, 2017, 08:07:51 PM »
More reports on PSCs

http://spaceweather.com/archive.php?view=1&day=14&month=02&year=2017

What else could cause the growth in PSCs than intercontinental aviation?
Modern planes like the Dreamliner cruise at very high altitudes, like 36 000 feet, well into the stratosphere.
Intercontinental aviation across the Arctic  has increased  quite a bit in recent years, with budget airlines like Virgin or Norwegian. Most flights from Europe to the US pass Greenland and Newfoundland, e.g. And dominating wind patterns will blow the contrail clouds further NE.


Sigmetnow

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Re: Aviation
« Reply #52 on: March 22, 2017, 04:48:09 PM »
Battery energy density is not yet where we need it to be, but given the curve of battery improvement, this is a noteworthy goal.

Quote
A new startup is trying the more ambitious goal of building a battery-powered 150-seat plane to compete with 737-size aircrafts in the market for short-haul trips (under 300 miles).
https://electrek.co/2017/03/22/electric-plane-startup-150-seat-battery-powered-plane/
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mati

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Re: Aviation
« Reply #53 on: March 22, 2017, 10:44:38 PM »
better yet to build an electric catapault and fire a glider to land in france :)
and so it goes

Sigmetnow

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Re: Aviation
« Reply #54 on: April 05, 2017, 01:05:22 AM »
Siemens’s New Electric Plane Just Broke the World Speed Record
Quote
In March, the 330LE set a new top-speed record for electric aircraft when it hit over 200 miles per hour over a slightly less than two-mile stretch. In the same demonstration, it also became the first electric aircraft ever to tow a glider to cruising speed and, in December, it also broke the electric climbing record. Demonstrated over Munich, Germany, the little battery-powered plane reached over 3,000 meters altitude in under four and a half minutes.

The new Siemens engine that makes this possible is a true marvel, providing a whopping 260 kW of power output while weighing just 110 lbs, overall. ...
https://www.inverse.com/article/29930-siemens-plane-electric-aircraft-330le-world-record-speed-battery
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Sigmetnow

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Re: Aviation
« Reply #55 on: April 06, 2017, 09:03:00 PM »
A small petrol engine supplemented with battery/electric power.

Zunum Aero emerges from stealth mode with big plans for hybrid electric planes
Quote
The idea is to create aircraft that are well-suited for routes that have fallen into disuse due to trends that have dominated the airline industry over the past few decades – trends that favor larger aircraft serving bigger airports.

Kumar cited figures suggesting that only 2 percent of the nation’s more than 5,000 airports account for 96 percent of today’s air traffic. That means the bigger airports are jammed, while scheduled service from the smaller airports is costly, if it exists at all.

Zunum Aero says the greater efficiencies of hybrid electric propulsion could reduce fares by 40 to 80 percent for routes ranging up to 1,000 miles.
...
Kumar said Zunum Aero has been working with the Center for Power Optimization of Electro-Thermal Systems at the University of Illinois on a technology approach that blends battery storage with engine-generated power. An onboard software system would calculate when the engine needs to be on, and for how long, depending on the route.
...
http://www.geekwire.com/2017/zunum-aero-stealth-hybrid-electric-planes/
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mati

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Re: Aviation
« Reply #56 on: April 09, 2017, 09:15:14 PM »
and so it goes

TerryM

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Re: Aviation
« Reply #57 on: April 10, 2017, 12:35:59 AM »
A small petrol engine supplemented with battery/electric power.

Zunum Aero emerges from stealth mode with big plans for hybrid electric planes
Quote
The idea is to create aircraft that are well-suited for routes that have fallen into disuse due to trends that have dominated the airline industry over the past few decades – trends that favor larger aircraft serving bigger airports.

Kumar cited figures suggesting that only 2 percent of the nation’s more than 5,000 airports account for 96 percent of today’s air traffic. That means the bigger airports are jammed, while scheduled service from the smaller airports is costly, if it exists at all.

Zunum Aero says the greater efficiencies of hybrid electric propulsion could reduce fares by 40 to 80 percent for routes ranging up to 1,000 miles.
...
Kumar said Zunum Aero has been working with the Center for Power Optimization of Electro-Thermal Systems at the University of Illinois on a technology approach that blends battery storage with engine-generated power. An onboard software system would calculate when the engine needs to be on, and for how long, depending on the route.
...
http://www.geekwire.com/2017/zunum-aero-stealth-hybrid-electric-planes/


I don't know if we're there yet, but I've long wondered about the possibility of using ICE during take off, then switching to electric during the cruising phase of the journey when power requirements would presumably be much less. I don't see how to attain an 80% drop in air fare because of fuel costs, particularly on short hops where capital costs, maintenance and labor costs could be expected to be relatively high, but some savings may be possible.


The slam dunk hybrid in my mind would be ships of every size. Very low speeds are required in harbors, canals and locks. Ships can accommodate the extra weight of batteries, electric motors and possibly solar panels, more readily than other transportation modes, and the fuels they customarily burn are the dirtiest out there.
I don't know how much fuel a cargo ship would save over the course of a voyage, but if all this accomplished was to improve air quality around harbors, canals, and locks, it might still be worthwhile.


Terry

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Re: Aviation
« Reply #58 on: April 10, 2017, 07:26:37 AM »
Don't know if this is significant, but airplanes taxi on the ground a lot, and with shorter flights and busier airports there is a higher proportion of taxiing.

From https://en.wikipedia.org/wiki/Taxiing :
Quote
At low power settings, combustion aircraft engines operate at lower efficiency than at cruise power settings. A typical A320 spends an average of 3.5 hours a day taxiing, using 600 litres (160 US gal) of fuel. Hybrid electrically driven nosegear are under development to allow high use aircraft to shut down the engines during taxi operations.[1]
Electric taxiing was invented by Delos Aerospace and patented in the US in 2007. Electric taxiing will significantly reduce aircraft fuel burn which is estimated to be as high as 27% of total fuel burn for a 90-minute flight where waiting in queue adds to the time on the ground.

mati

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Re: Aviation
« Reply #59 on: April 10, 2017, 03:24:31 PM »
there are also taxi bots :O

http://www.taxibot-international.com/
and so it goes

Sigmetnow

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Re: Aviation
« Reply #60 on: April 21, 2017, 01:25:20 AM »
Lilium shows maiden flight of world’s first working prototype of an electric VTOL jet
https://electrek.co/2017/04/20/lilium-electric-vtol-jet/
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Bob Wallace

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Re: Aviation
« Reply #61 on: April 21, 2017, 02:25:03 AM »
To answer an earlier question, yes, Hyperloop.

A faster, more convenient, more comfortable, and less expensive way to travel long distances powered by renewable electricity.  If is works we could replace "80%" of air travel with 'loops.  We'd still need planes for island and remote village stuff. 

Reading through the posts it looks like moderate range (500 mile?) battery powered flying is going to be possible.  And then, worst case, biofuels/synfuel for necessary longer range flying.


rboyd

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Re: Aviation
« Reply #62 on: April 21, 2017, 03:52:00 AM »
The hype loop seems to be in full bloom, reminds me so much of the .com bubble. I wish I were wrong, but it will take decades for this stuff (hyperloop and electric planes) to turn into actual commercial reality that has a significant impact. Reality is that we will have to stop flying so much to reduce carbon emissions.

The Chinese, Japanese, Europeans etc. have built/are building fast conventional trains that make short-haul flights unnecessary. North Americans should be doing the same.

Realistic comment with respect to Lilium:

"Based on the renderings, the “jet” will fly, but not far, says Charles Eastlake, an aerodynamicist at Embry-Riddle Aeronautical University. Concepts like this often soar on hopes and dreams before slamming into hard realities, he says.

Eastlake knows what he’s talking about—he has a long history with electric and vertical-lift aircraft, including the Navy’s experimental XFV-12 fighter in the 1970s. “In general, the public has a hopelessly optimistic view about how straightforward and wonderful electric vehicles are,” he says—a view that often doesn’t consider the challenges of safety, weight, and cost."

https://www.wired.com/2016/06/lilium-electric-personal-jet-concept/

Bob Wallace

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Re: Aviation
« Reply #63 on: April 21, 2017, 04:14:55 AM »
If we want to discuss the 'loop there's a thread for that, but let me say that IMO we should not be building HSR in the US right now.  We should hold off for a few months to a couple of years and let the 'loop get tested.

If it works we're probably better off to skip rail and go straight to tubes. 

Sigmetnow

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Re: Aviation
« Reply #64 on: April 26, 2017, 12:20:06 AM »
Ummm....   :o

Uber unveils plans for electric flying taxis by 2020, ChargePoint will provide charging for first stations
Quote
If you are wondering how come there are so many news and announcement about electric vertical takeoff and landing (eVTOL) aircraft lately, like Lilium’s maiden flight and Kitty Hawk coming out of stealth, it looks like it’s because they timed the releases with Uber’s Elevate Summit in Dallas this week.

Today, Uber announced its own plans to use eVTOL aircraft for a flying taxi service.

Several companies, including the ones previously mentioned, detailed their plans during the event. Uber describes the summit:

“The Summit will offer an information-packed three days during which we hope to build awareness about the Elevate mission, detail Uber’s role in the ecosystem, identify and accelerate opportunities to collaborate within the community, and define a path towards initial urban eVTOL operations.”
...
https://electrek.co/2017/04/25/uber-electric-flying-taxis-2020-chargepoint-charging-station/
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TerryM

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Re: Aviation
« Reply #65 on: April 26, 2017, 04:18:55 PM »
Ummm....   :o

Uber unveils plans for electric flying taxis by 2020, ChargePoint will provide charging for first stations
Quote
If you are wondering how come there are so many news and announcement about electric vertical takeoff and landing (eVTOL) aircraft lately, like Lilium’s maiden flight and Kitty Hawk coming out of stealth, it looks like it’s because they timed the releases with Uber’s Elevate Summit in Dallas this week.

Today, Uber announced its own plans to use eVTOL aircraft for a flying taxi service.

Several companies, including the ones previously mentioned, detailed their plans during the event. Uber describes the summit:

“The Summit will offer an information-packed three days during which we hope to build awareness about the Elevate mission, detail Uber’s role in the ecosystem, identify and accelerate opportunities to collaborate within the community, and define a path towards initial urban eVTOL operations.”
...
https://electrek.co/2017/04/25/uber-electric-flying-taxis-2020-chargepoint-charging-station/


Wouldn't this require an almost complete re-write of existing FAA regulations? If the hardware was available today, I doubt that 3 years is enough time to shepherd whatever legislation is needed through whatever committees are required, assuming that someone already knows how flying taxis should be regulated.


Do passengers require FAA screening?
Are Air Cabs restricted to licensed airports and helicopter pads?
If an A-Cab avoids telephone lines, clotheslines and tree branches, can it land on your driveway?
Who is responsible when an inebriated passenger vomits on my garden party?
What licensing is required for one to use a public roadway?


I think I could continue for a long time, but the point I'm hammering at is that even carrying someone from an already crowded airport to the heliport of his choice, will require changing the laws and codes, and this service won't be of much use to most people.


A taxi is generally considered as a conveyance that picks you up where you are located & drops you close to where you need to be. This won't be possible for an Air Cab by 2020.
This is vaporware.


Terry

Sigmetnow

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Re: Aviation
« Reply #66 on: April 26, 2017, 05:44:47 PM »
The FAA (and its global counterparts) already has detailed regulations regarding aircraft separation; distance required from structures, vessels, or people; and designated airspace where increasing levels of air traffic control is required.

But it's interesting that even Elon Musk has said he's not big on flying cars because with Teslas, "at least you don't have to worry about one falling on your head."  ;D
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rboyd

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Re: Aviation
« Reply #67 on: April 27, 2017, 09:19:25 PM »
Its a shame that the major international aviation treaty has a section banning the taxation of jet fuel, giving a free ride to the aviation industry. Quickest way to reduce air travel, and accelerate the drive for greater efficiency, would be to tax jet fuel the way we tax gasoline.

Bob Wallace

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Re: Aviation
« Reply #68 on: May 29, 2017, 10:49:48 PM »
Battery energy density is not yet where we need it to be, but given the curve of battery improvement, this is a noteworthy goal.

Quote
A new startup is trying the more ambitious goal of building a battery-powered 150-seat plane to compete with 737-size aircrafts in the market for short-haul trips (under 300 miles).
https://electrek.co/2017/03/22/electric-plane-startup-150-seat-battery-powered-plane/

Quote
Hyperloop proposed to include magnetic levitation and linear electric motor propulsion inside a partial vacuum tube. Extreme high-speed trains already operate between China’s largest cities using magnetic levitation and linear motors.

A portion of that same infrastructure could be installed at airports that serve heavy freight transport aircraft, where a magnet suspended carriage would carry and accelerate an aircraft to well above its usual lift-off-speed.

At the present time, the Russian built Antonov AN-225 at 640 tons is the heaviest freight aircraft built. Much of its power is required to accelerate along a runway to lift-off speed before climbing to its cruising altitude. Mag-lev runways could theoretically accelerate a craft weighing well in excess of 1,500 tons to well above its lift-off speed....

http://maritime-executive.com/editorials/seeking-game-changers-for-international-freight

By using "ground power" to get planes into the air we could greatly cut the amount of battery storage necessary for electric flight.  Use batteries only for the cruising part.  This could move us to battery powered flight many years sooner.

And stick these new airports well outside urban areas.  Establish departure terminals around the area using Hyperloop systems to feed passengers to the airports that service flights over oceans.

Sigmetnow

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Re: Aviation
« Reply #69 on: June 17, 2017, 05:28:38 PM »
100 European Airports to Go Climate Neutral by 2030
Commitment in Support of Paris Agreement Goals
Quote
100 European airports are to be carbon neutral by 2030, according to the planning of the European branch of Airports Council International (ACI Europe). The council this week doubled its carbon neutrality target for 2030 in support of the central goal of the Paris Climate Change Agreement, which is to hold the global average temperature rise to as close as possible to 1.5°C.

Carbon emissions generated by airport operations account for up to 5% of total emissions from the aviation sector, and engagement of the airport industry is key to achieving the goals set out in the Paris Agreement. The aviation industry has a major interest in preventing more extreme weather from climate change, as more storms, heatwaves and turbulence will directly affect air travel.
...
http://newsroom.unfccc.int/climate-action/100-european-airports-to-go-climate-neutral-by-2030/
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Tor Bejnar

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Re: Aviation
« Reply #70 on: June 17, 2017, 06:14:38 PM »
Laudable, but that's the 'airport operations', not the airplanes that operate there (when on the ground).
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numerobis

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Re: Aviation
« Reply #71 on: June 17, 2017, 08:57:04 PM »
Laudable, but that's the 'airport operations', not the airplanes that operate there (when on the ground).

Airport ops burns a lot of fuel, produces a lot of local air pollution.

Electric aircraft tugs could taxi the aircraft around from terminal to runway and save that fuel, without needing to be carried up to the sky. Right now we don't use tugs around the airport much (except to push back) because they're expensive -- they are human-operated. It wouldn't be much of a technical challenge to retrofit a system to let the pilot control the tug though.

Tor Bejnar

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Re: Aviation
« Reply #72 on: June 17, 2017, 11:12:28 PM »
It would be great if planes could power-down at the (slow) end of the runway, get 'picked up' by an autonomous EV tug that also feeds the airplane's electrical system (AC, lights), and be dragged silently to the terminal.
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Bob Wallace

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Re: Aviation
« Reply #73 on: June 18, 2017, 12:27:59 AM »
It would be great if planes could power-down at the (slow) end of the runway, get 'picked up' by an autonomous EV tug that also feeds the airplane's electrical system (AC, lights), and be dragged silently to the terminal.

I doubt that much of the total energy of flying would be saved.  The mass is already in motion and goes about a mile at low speed.


Sigmetnow

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Re: Aviation
« Reply #74 on: June 18, 2017, 02:11:40 AM »
It would be great if planes could power-down at the (slow) end of the runway, get 'picked up' by an autonomous EV tug that also feeds the airplane's electrical system (AC, lights), and be dragged silently to the terminal.

The idea of putting electric motors in airplane wheels for "green taxiing" goes back several years.  The most recent thing I find on it is this:
https://aviation.stackexchange.com/questions/24430/why-dont-large-commercial-airplanes-have-electric-motors-in-the-wheels

Here's an article from 2012:  http://www.idtechex.com/events/presentations/hybrid-aircraft-electric-drive-for-ground-taxi-boeing-trial-002975.asp
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Sigmetnow

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Re: Aviation
« Reply #75 on: June 18, 2017, 02:23:22 AM »
Aircraft don't do well in extreme heat, for many different reasons affecting engine operation, flight characteristics, and passenger comfort, to name a few.  Planes parked at the gate have actually sunk into a softened tarmac surface!

This week's heat wave in the southwest U.S. is expected to affect airlines.  (Ref: Phoenix, Arizona's Sky Harbor airport.  Canadair Regional Jets.)

"The forecast for @PHXSkyHarbor calls for preposterous high temperatures over 120° F (49° C) & @AmericanAir may not be able to operate CRJs."
https://twitter.com/airlineflyer/status/876205450009747457

"I'm told by @AmericanAir that CRJs have an operational limit of around 118° F, so at the hottest time of day they may be temporary grounded."
https://twitter.com/airlineflyer/status/876205689135353857
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Sigmetnow

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Re: Aviation
« Reply #76 on: June 20, 2017, 04:13:57 PM »
The Science Of Why It's Too Hot For Some Planes To Fly In The Southwest U.S.
Quote
...
The Arizona Republic reported that around 50 flights for Tuesday were cancelled at Phoenix Sky Harbor International Airport. These were primarily regional flights. According to The Arizona Republic:

a statement from American Airlines, the American Eagle regional flights use the Bombardier CRJ aircraft, which has a maximum operating temperature of 118 degrees. Tuesday's forecast for Phoenix includes a high of 120 degrees, and the flights that are affected were to take off between 3 and 6 p.m.....Larger jets that fly out of Sky Harbor have higher maximum operating temperatures: Boeing, 126 degrees, and Airbus, 127 degrees
...
https://www.forbes.com/sites/marshallshepherd/2017/06/20/the-science-of-why-its-too-hot-for-some-planes-to-fly-in-the-southwest-u-s/
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Sigmetnow

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Re: Aviation
« Reply #77 on: June 21, 2017, 11:56:33 PM »
A new all-electric aircraft with a range up to 600 miles unveiled at Paris Air Show
Quote
At the 52nd International Paris Air Show, Eviation Aircraft, a member of NASA’s on-demand mobility program, unveiled the first prototype of a new all-electric aircraft concept with a range of up to 600 miles (965 km)....

While it was the prototype’s debut this week, Eviation says that they are already flying proof of concept missions, and they plan to move into certification and commercialization as soon as next year.
...
Eviation claims that its electric aircraft is made possible by a new aluminum air battery....
https://electrek.co/2017/06/21/all-electric-aircraft-eviation/
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rboyd

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Re: Aviation
« Reply #78 on: July 13, 2017, 07:52:11 PM »
Climate-friendly air travel - say what?

Good article on the challenges for reducing aviation emissions. Points to the significant subsidies provided to the airline industry such as a lack of taxes on airline tickets and jet fuel, and no carbon taxes on flights. A big carbon tax (taking into account the much greater impact of emissions at altitude) would certainly drive some speed up in the level of innovation.

http://www.dw.com/en/climate-friendly-air-travel-say-what/a-39549089

Sigmetnow

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Re: Aviation
« Reply #79 on: August 10, 2017, 06:32:05 PM »
All-electric, autonomous, intra-city air taxi being developed for use in Dubai.  18 rotors.  9 battery packs.  30 minute flying time.

All-electric vertical take-off and landing aircraft gets $30 million investment led by Daimler
https://electrek.co/2017/08/10/all-electric-vertical-take-off-and-landing-aircraft-volocopter-daimler/
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rboyd

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Re: Aviation
« Reply #80 on: August 10, 2017, 09:08:40 PM »
All-electric, autonomous, intra-city air taxi being developed for use in Dubai.  18 rotors.  9 battery packs.  30 minute flying time.

All-electric vertical take-off and landing aircraft gets $30 million investment led by Daimler
https://electrek.co/2017/08/10/all-electric-vertical-take-off-and-landing-aircraft-volocopter-daimler/

The picture says it all, the rich being able to fly above the reality of the 99% below them from their luxury apartment to their luxury office. The world below them may be dystopian, but they are safely immune. Maybe the next innovation is really cheap surface to air missiles for the masses?

numerobis

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Re: Aviation
« Reply #81 on: August 10, 2017, 09:54:30 PM »
Surely the masses will be using rail guns powered by renewable electricity.

TerryM

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Re: Aviation
« Reply #82 on: August 10, 2017, 09:57:19 PM »
All-electric, autonomous, intra-city air taxi being developed for use in Dubai.  18 rotors.  9 battery packs.  30 minute flying time.

All-electric vertical take-off and landing aircraft gets $30 million investment led by Daimler
https://electrek.co/2017/08/10/all-electric-vertical-take-off-and-landing-aircraft-volocopter-daimler/

The picture says it all, the rich being able to fly above the reality of the 99% below them from their luxury apartment to their luxury office. The world below them may be dystopian, but they are safely immune. Maybe the next innovation is really cheap surface to air missiles for the masses?
Little Bubba will get good practice for duck season. Better to go back to our luxurious underground palaces linked by silent, speedy TeslaTunnels. The whole trickle down thing lost it's glory when holding tanks were installed.
Terry

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Re: Aviation
« Reply #83 on: August 11, 2017, 01:29:05 PM »
Another way of looking at this:  compare it with Elon Musk and his Tesla Roadster. Taking a big chance, investing millions on a new form of sustainable transportation — at first available only to the very rich, but within a few years affordable to a majority of the population. I say, props to Dubai for advancing this very new form of clean air travel.  It will help advance the introduction of bigger electric planes and reduce aviation's carbon footprint.
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numerobis

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Re: Aviation
« Reply #84 on: August 11, 2017, 05:16:04 PM »
I hate the electric plane policy. It might end up being the way of the future, but for terrible reasons.

Most short-range flight (1,000 km or less) could be replaced by a train, which would be safer, more efficient, faster, cheaper. Exception would be short flights that cross large bodies of water, or short flights between small communities.

A long-range flight would require a huge improvement in energy density. I'm not sure batteries are even theoretically capable.

The only reason not to replace the short-range flights with trains is political will. Which I suspect means that in practice we're stuck with electric planes.

ghoti

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Re: Aviation
« Reply #85 on: August 11, 2017, 06:36:31 PM »
Quote
The only reason not to replace the short-range flights with trains is political will. Which I suspect means that in practice we're stuck with electric planes.
If only this were true. The reason short-range flights have not already been replaced with trains has been shown over and over again to be cost of building fast train lines.

The amount of money involved is so huge that only governments can finance it but very few can ever come up with the funding. Remember this kind of travel is only for a very small percentage of the population. The costs are much too high relative to the votes associated with them.

numerobis

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Re: Aviation
« Reply #86 on: August 11, 2017, 08:55:15 PM »
ghoti: you say I'm wrong but then you write the same argument that I made. I'm confused. The cost of high-speed rail is much lower than the cost of air transit. The up-front cost is higher, but the operating cost is much lower. Why does society decide to pay for short-haul air transit rather than high-speed rail? That's exactly a question of political will.

Close to half of all Americans fly in any given year. In Europe it's lower because there is a decent rail network. There's no shortage of individuals flying around.

Bob Wallace

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Re: Aviation
« Reply #87 on: August 11, 2017, 09:39:28 PM »
Quote
Why does society decide to pay for short-haul air transit rather than high-speed rail?

Lack of consideration of overall cost?  Lack of knowledge about overall cost?

Building a HSR system is a huge cost that has to receive commitment before work commences. 

Airport expansions happen here and there and  largely out of public sight. 

HSR construction is also disruptive for those along the route. 

Carbon costs are never included.

Sigmetnow

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Re: Aviation
« Reply #88 on: August 11, 2017, 09:54:38 PM »
Numerobis wrote: “The only reason not to replace the short-range flights with trains is political will. …”

Other reasons:
- Adverse Terrain
- Environmental Damage/disruption
- “Not in my backyard” and quality of life issues
- Track/ roadbed maintenance costs, including climate-change related risks
- Cost of tracks extending to small communities:  Vertical takeoff and landing aircraft allow “point to point” feeder transportation to and from big towns (small/rooftop heliports) and small towns (little more than a decent sized parking lot or field required, versus miles of tracks and potentially underused train stations).
- More flexible scheduling of air travel make transportation to small towns feasible where the cost of a track for only an occasional use would be prohibitive.

Quote
Siemens will bring this technology to its electric flight collaboration with Airbus. The two companies hope to prove the technical feasibility of hybrid electric drive systems for regional aircraft by 2020. This will require power ratings of up to 10 megawatts. “We expect to see the first aircraft with up to 100 passengers and a range of approximately 1,000 kilometers by 2030,” said Anton.
https://chargedevs.com/newswire/electric-airplane-with-siemens-drive-system-sets-ascent-record/

Airbus and Siemens collaborate on hybrid electric propulsion systems for aircraft
https://chargedevs.com/newswire/airbus-and-siemens-collaborate-on-hybrid-propulsion-systems-for-aircraft/
People who say it cannot be done should not interrupt those who are doing it.

rboyd

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Re: Aviation
« Reply #89 on: August 11, 2017, 10:53:37 PM »
Building railways doesn't seem to be a problem in Europe, Japan or China. An issue of political will and the strength of the airline and other fossil fuel lobbies perhaps, in North America.

ghoti

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Re: Aviation
« Reply #90 on: August 11, 2017, 11:09:23 PM »
Building railways doesn't seem to be a problem in Europe, Japan or China. An issue of political will and the strength of the airline and other fossil fuel lobbies perhaps, in North America.
More like density of population serviced. Many many more people per train-mile.

Bob Wallace

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Re: Aviation
« Reply #91 on: August 12, 2017, 01:23:42 AM »
Density and history.

Many US cities are relatively new and grew up around the automobile.  Most European cities (like the oldest US cities) developed using more public transportation.

In Europe people have always had the Metro, the Tube and local trains.  There was a familiarity with rail transport.  That's not true in the US.  I would be surprised if more than 25% of all Californians have ever been on a train. 

In Europe you were already traveling city to city by rail.  HSR was an improvement on technology already in use.  In the US passenger rail is unknown to most people.

wili

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Re: Aviation
« Reply #92 on: August 12, 2017, 02:48:25 AM »
wellll, some cities are newer than rail. But many/most current major US cities had extensive rail and trolley systems in the US up till the 40's and 50's when mostly corrupt politicians influenced by car, oil, concrete and other interests arranged to have them ripped out. This is well documented history. Try it some time.

And of course Europe hasn't "always'' had Metro, etc. When they did get new kinds of public transport though, it was often an occasion for celebration and compositions!  ;D :

https://www.sciencedaily.com/releases/2014/02/140212093136.htm

"A force de chercher de bonnes raisons, on en trouve; on les dit; et après on y tient, non pas tant parce qu'elles sont bonnes que pour ne pas se démentir." Choderlos de Laclos "You struggle to come up with some valid reasons, then cling to them, not because they're good, but just to not back down."

Bob Wallace

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Re: Aviation
« Reply #93 on: August 12, 2017, 03:01:17 AM »
LA, for example, had 1.5 million people in 1940.  Few who made use of the trolley system are still alive and kicking.  Most of the current 4 million people now living in LA have no trolley memories.

You can blame "the corporations" for tearing out US urban rail systems, but I don't think there was much of a public outrage.  People were moving into a new age of cars and buses.

The US (outside of NYC and possibly a few other NE cities) have a very heavy car mindset.

I'm not arguing that that's good, just that it exists.  US people, in general, see no value in HSR.  I differ because I've used HSR in Europe and Asia, traveling to places with really good public transportation systems. 

HSR to many US cities and then?  Get jerked around by taxi costs or spend major amounts of time waiting for a bus?

rboyd

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Re: Aviation
« Reply #94 on: August 12, 2017, 07:20:57 PM »
The building of the motorway network was funded by the government after WW2, which together with the destruction of trollies etc. by the car/oil companies, lead to the suburbanization of the US. Helped by many other public policies, such as zoning laws.

Yes, "we are where we are" but the problem is that its not where we need to be. We need people in power who actually believe in climate change AND will act as if it a real emergency (unlike the incrementalism of Obama, Clinton, Trudeau, Merkel etc.). Otherwise, we run the risk that when the SHTF we will see extreme right wing populism (Trump on steroids) rather than constructive governance.

With CO2e well above 500ppm, we need immediate and large cuts in emissions. The market by itself will not supply that. Emissions from aviation by 2030 will be much larger than now and we will probably be close to blowing 2 degrees by then.

numerobis

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Re: Aviation
« Reply #95 on: August 12, 2017, 10:36:34 PM »
Quote
Quote
Siemens will bring this technology to its electric flight collaboration with Airbus. The two companies hope to prove the technical feasibility of hybrid electric drive systems for regional aircraft by 2020. This will require power ratings of up to 10 megawatts. “We expect to see the first aircraft with up to 100 passengers and a range of approximately 1,000 kilometers by 2030,” said Anton.
https://chargedevs.com/newswire/electric-airplane-with-siemens-drive-system-sets-ascent-record/

Airbus and Siemens collaborate on hybrid electric propulsion systems for aircraft
https://chargedevs.com/newswire/airbus-and-siemens-collaborate-on-hybrid-propulsion-systems-for-aircraft/
[/quote]

I have no doubt we can make practical short-range electric planes with current or soon-to-be-developed tech.

But there's a limit to the range. Let's say you have a plane that can uses 1 kWh per km. It currently goes 1,000 km max range. Now let's redesign it to go 1,100 km. The energy storage mass needs to increase 10% assuming it has the same efficiency. But now you've got a plane that 10% heavier -- so it's using more energy per km. In other words, you need to burn more energy just to bring the extra energy with you.

In the end, the math on that is exponential: no matter how much range you have now, to go an extra km, you need to bring an extra x% more mass in storage. Theoretically you can go any range, but your plane becomes exponentially more expensive as you extend the range.

On top of that you will soon find that your engines aren't powerful enough, your wings not large enough, and your landing gear doesn't distribute the weight enough, so you need to expand those, which means you now need more energy, which etc etc -- and that leads to a hard physical limit based on the efficiency of your engines and airframe versus the energy storage density.

Gasoline (whether from petroleum or from modern plants) has two huge advantages in this game over batteries: (1) it's much denser than even the theoretically best lithium battery; (2) you aren't always carrying all the mass -- you can take off with less mass if you've got a short flight, and you (almost) always land with a light plane.

Bob Wallace

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Re: Aviation
« Reply #96 on: August 13, 2017, 12:24:35 AM »
Energy mass needs to increase to extend range. 

Or energy capacity per mass needs to increase to increase range.

Historically battery capacity has been increasing 8% a year.  That's actually a stairstep history, not some sort of smooth linear increase, but capacity has grown and there's no theoretical reason it shouldn't continue to increase.

Gasoline (actually jets burn high grade kerosene) does have a energy/mass advantage but there's that nasty carbon problem we have to solve. 

And I'm not sure about kero's advantage over the best theoretical battery.  Remember, there's a very large efficiency difference between electric motors and turbines.  Musk has said that battery powered flight becomes practical when batteries reach about 400 Wh/kg.  Currently we're around 250 Wh/kg in use, higher claims in the labs.  I think the theoretical limit for lithium-ion is about 1,000 Wh/kg.

numerobis

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Re: Aviation
« Reply #97 on: August 13, 2017, 03:30:59 PM »
I've read the theoretical max for lithium is more like 60x what's currently available; the 4x must be for lithium-cobalt? Regardless, it's much less dense than jet fuel.

This is the one place where I expect we'll be using renewable energy to make liquid fuel, rather than using batteries. Hopefully we settle on a fuel that burns cleaner than kerosene.

ghoti

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Re: Aviation
« Reply #98 on: August 14, 2017, 10:33:27 PM »
I often wonder why there is so little consideration for biofuel for aviation to reduce (or eliminate) net carbon emissions from planes. It is proven technology which is mostly limited by high cost at this point.

Turns out biofuels can also reduce  other pollution currently emitted by jet engines.

https://climate.nasa.gov/news/2580/nasa-study-confirms-biofuels-reduce-jet-engine-pollution/#.WP-pErf3r4g.facebook

magnamentis

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Re: Aviation
« Reply #99 on: August 15, 2017, 01:11:01 AM »
I often wonder why there is so little consideration for biofuel for aviation to reduce (or eliminate) net carbon emissions from planes. It is proven technology which is mostly limited by high cost at this point.

Turns out biofuels can also reduce  other pollution currently emitted by jet engines.

https://climate.nasa.gov/news/2580/nasa-study-confirms-biofuels-reduce-jet-engine-pollution/#.WP-pErf3r4g.facebook

depends which biofuel, fuel from "FOOD" is a bullet in starving peoples foot as well as bad for those who cannot easily or at all afford raising basic food prices like corn, wheat and the likes.

there are many enough examples where biofuel has started to produced ins significant quantities while they were far from the quantities needed to replace fossil fuel and already there have arisen serious issues as mentioned above and more.

food, as long as there are people who starve on this planet is a crime to be used for energy purposes hence if biofuel it has to be produced from real waste and with very strong regulations.

the regulations needed i don't trust will be implemented due to our corrupt and lobby driven
political system, especially once the big players join the party in serious.