Electric planes

[Thekiwi]

Damn

Eviation Alice electric plane prototype damaged but 'intact' after fire

 

[Thekiwi]

Airbus is working on a hybrid passenger airliner, where one of four engines is replaced with an electric motor, with capability to replace a 2nd engine with electric as well. Seems like a good interim solution on the face of it to Significantly reduce carbon emissions from air travel.

Annoying though it is taking them so long to get the prototype flying, it was announced in 2017 and first flight is expected in 2021 (it’s using an existing plane design).

E-Fan X

 

[PhantomX]

4 years is fast in aerospace world. Even though this is a demo, it still needs to satisfy many of regulatory requirements in order to get an experimental type certificate. Very interesting to see their test results.

 

[swaltner]

I ordered a Pipistrel Taurus Electro. Lots of information about it earlier in this thread. Initial indication was for delivery in September.

 

[Cirrus MS100D]

I ordered a Pipistrel Taurus Electro. Lots of information about it earlier in this thread. Initial indication was for delivery in September.

Congrats! They look beautiful and seem to be a perfect blend of elegance and futuristic propulsion!

 

[lolachampcar]

swaltner,
Love to hear your thoughts. I'd would really like to do something electric on the flying side.

 

[swaltner]

Making progress on the Taurus Electro purchase. They’ve started construction and we’re still looking like I’ll take delivery in September, right at the end of this year’s gliding season.

@1.21GW would be proud of me for reserving N121GW as the N-Number for the electric-powered airplane in my future. I’m actually surprised it was available. A friend that had previously had a reservation on it for a possible project suggested it as a suitable vanity N-Number.

 

[JetFalcon]

If all airlines switched to electric planes, does that mean airplane noise would not be an issue anymore? Would they sound like buzzing bees like a drone? Or can it sound like a Tesla.

I wouldn't mind living next to an airport if the planes sounded like Teslas.

 

[Etna]

Noise would still be an issue, because it is coming from the air being violently pushed to propel the aircraft, rather than just the engine itself.

It is especially the case when local airflow gets near the speed of sound, such as a propeller blade tip or a turbofan exhaust, being electrically powered or not.

New airplanes do get quieter though, thanks to sophisticated computer programs that can predict noise fairly accurately. Also electric propulsion opens up new aircraft design layout possibilities, such as distributed propulsion (many smaller propellers), but most of the noise reduction in the future will be achieved thanks to new Computer Fluid Dynamics tools that can predict noise. Most new eVTOLs under development are making extensive use of it.

The keyword is aeroacoustics.

Having said all that, medium to long haul flights will remain out of reach of electric propulsion for many years still.

 

[SmartElectric]

If all airlines switched to electric planes, does that mean airplane noise would not be an issue anymore?

Full Page Reload

That same EU program also aims to reduce aircraft noise by half by 2050. And that, it turns out, is the greatest motive of the airline industry right now. Just to get around restrictions on nighttime flights, airlines sometimes spend money to muffle their older, louder planes, a job called “hush kitting.”

“That was the biggest surprise when Siemens started talking to airlines,” Anton says. “I was always mentioning quiet operation as the third thing, after energy and emissions. Now it’s the first thing.”

This wouldn’t be the first green technology to succeed for reasons having little to do with global warming. People bought the hybrid Prius to save on gas; they buy the Tesla to out-accelerate a Porsche. Airlines will buy hybrid-electric airplanes for their quiet operation, and lower greenhouse gas emissions will come almost as a side effect. But they will come.

 

[ke6jph]

Currently an unconfirmed rumor that Elon is looking for or has purchased property near the airport at Lake Havasu City, Arizona for construction/ testing of aircraft. Source seems to be honest/ truthful.
Thoughts?

 

[replicant]

Currently an unconfirmed rumor that Elon is looking for or has purchased property near the airport at Lake Havasu City, Arizona for construction/ testing of aircraft. Source seems to be honest/ truthful.
Thoughts?

Would you mind sharing more about the rumor? Was Elon seen there and the visit purpose simply deduced from the location? Did you hear it directy from someone who claim to know? Is it discussed online? …?

 

[replicant]

Currently an unconfirmed rumor that Elon is looking for or has purchased property near the airport at Lake Havasu City, Arizona for construction/ testing of aircraft. Source seems to be honest/ truthful.
Thoughts?

I hope this will be a Tesla project because bringing electric aircrafts is obviosly part of Tesla's mission ("Tesla’s mission is to accelerate the world’s transition to sustainable energy"), contrary to any other Musk's enterprises. Launching another company for electric aircraft would make both companies compete in more ways than SpaceX (or Boring Co) & Tesla do already.

Plus, I know Elon wouldn't IPO the new entity early so this must be Tesla's

 

[Etna]

As I mentioned in the investors thread, I don't believe that rumour to be true. Let me explain why.

Elon has obviously a keen interest in making this happen, unfortunately aviation, unlike ground transportation, is not a low hanging fruit for transition to sustainable energy, with the exception of very short range applications such as eVTOLS. As soon as you look at anything beyond 100-150 miles, the weight of the batteries becomes very problematic. At least 800-1000 Wh/kg energy densities are needed before we can start talking medium ranges (400-800 miles), forget about long ranges.

Also worth mentioning that, IMHO, Hyperloop is going to be a formidable competitor to aviation at some point, even on transcontinental ranges. Reason is that an aircraft spends most of its energy pushing molecules of air out of its way, and Hyperloop in vacuum enjoys mind blowing energy efficiencies.

For intercontinental travel, well there is Vomit Comet StarShip point-to-point.

Elon often refers to an electric VTOL supersonic electric jet that he is thinking about, but to me that sounds more like pointing towards something absurdly difficult as a matter of thought process. I just don't see a way to make this work, unless you consider battery energy densities well into the thousands of Wh/kg.

 

[Buckminster]

As I mentioned in the investors thread, I don't believe that rumour to be true. Let me explain why.

Elon has obviously a keen interest in making this happen, unfortunately aviation, unlike ground transportation, is not a low hanging fruit for transition to sustainable energy, with the exception of very short range applications such as eVTOLS. As soon as you look at anything beyond 100-150 miles, the weight of the batteries becomes very problematic. At least 800-1000 Wh/kg energy densities are needed before we can start talking medium ranges (400-800 miles), forget about long ranges.

Also worth mentioning that, IMHO, Hyperloop is going to be a formidable competitor to aviation at some point, even on transcontinental ranges. Reason is that an aircraft spends most of its energy pushing molecules of air out of its way, and Hyperloop in vacuum enjoys mind blowing energy efficiencies.

For intercontinental travel, well there is Vomit Comet StarShip point-to-point.

Elon often refers to an electric VTOL supersonic electric jet that he is thinking about, but to me that sounds more like pointing towards something absurdly difficult as a matter of thought process. I just don't see a way to make this work, unless you consider battery energy densities well into the thousands of Wh/kg.

Elon thinks 400 Wh/kg is sufficient:

So there was again a recent interview with Elon where he talked about his vision for electric planes with a lot of partly new and good information about how he looks on this concept. To me it seems everytime he is asked about he expresses a really big interest in going forward with the concept, but always says the he has to prioritize. There was a lot of good discussion on this in the "Elon Musk" thread that perhaps should be moved to this thread, or made in to a new thread ("Elon Musks vision for Electric planes" or something).

Anyway, since I wanted to hear him answer the question about electric planes again I thought I might aswell transcribe his answer for the record here:

AeroAstro Centennial Webcast (question starts at 37.22)

Interviewer: As much as we love Teslas, we are an aeronautics department and we are really interested in the potential for electric aircraft.

Elon: Sure, I love the idea of an electric aircraft. Everything will go fully electric, except for rockets. [Laugh] Ironic.

Interviewer: We think that in terms of energy density, to make transport aircraft physical, you will need improvements in the order of 10 to 100.

Elon: What! No, that's not... Wait, when you say 10 to 100 from what baseline? What do you mean?

Interviewer: A current Ion-Lithium...

Elon: Oh no, no no definately not. So, in my opinion at least, where we are right now at roughly, you know for a cell that doesn't have lots of other draw-backs, which people always forget to mention when they talk about battery break-throughs, there are many parameters that are important for a battery, and hardly a week goes by without some big break through - alledgedly - in batteries but the ******** factor is outrageous. But for real cells, that actually work and don't have some huge draw-back, they're currently at about 300 Wh/kg. To have a compelling aircraft you only really need about 400 Wh/kg - provided the percentage of cell on the aircraft is high. It doesn't need to be anywhere as high as it is on a rocket, but if it's at the sort of 70% level at 400 Wh/kg you can do very decent range. And if you move it up to sort of mid to high 70's you can go transcontinental. Not intercontinental but sort of west coast to east coast. You need an efficient aircraft but that's approximately, by my calculations, the numbers you need: 400 Wh/kg mid to high 70's cell to mass fraction. Which I think is achievable numbers. Aircrafts have all these unnessecary things like tails, rudders and elevators - like "not needed". [Laughing]. Just gimbal the electric fan. For some wierd reason gimballing motors is normal in rockets and not in aircraft. Why not?

Interviewer: Ok, definate plans to get in to this business and we'd love to see how things develop in that particular area. Do you have any specific plans?

Elon: I mean, I have been sort of toying with the design for an electric supersonic vertical take-off and landing aircraft for a while. I'd love to do it. But I think my mind would explode, like the brains worn out or saturated from working on electric cars and rockets.

 

[Etna]

Elon thinks 400 Wh/kg is sufficient:

Yes the trick is that he's working at 70% mass fraction for the cells weight / takeoff weight. That's Rutan Voyager level (which I saw at Oshkosh in 1987 ).

Let's see, Voyager fuel weight 7000 lb * 400 Wh/kg = 1270 kWh. That's equivalent to 130 hp during 13 hours, which allowed Voyager to cruise at 115 mph, so that's 1500 miles, or nearly LA to Houston no winds. Yeah I can see where he got his numbers.

It can be done at the expense of extraordinary design compromises, I was referring to more practical means of transportation. I am running my performance models with regional aircraft and things like that.

 

[lolachampcar]

Etna,
Keep posting please

 

[Zapped]

How important is the aircraft landing weight ? I assume the used fuel during flight would help with landing and stopping the plane.
Is this a small factor to consider ?

 

[Etna]

How important is the aircraft landing weight ? I assume the used fuel during flight would help with landing and stopping the plane.
Is this a small factor to consider ?

Fuel used during flight is pretty small for short haul airplanes. About 2% per 100 nautical miles, whether it is a four seat piston or a large regional aircraft (specifically for the ATR-72 over 100 nm it is 853 lb fuel for 50700 lb takeoff weight).

A 2-4% weight reduction results in landing performance changes that are in the noise levels. So basically electric airplanes are like short haul airplanes, they can land routinely near their maximum takeoff weight. Moreover, takeoff distances (and rejected takeoffs) are more limiting factors than landing distances.

 

[Etna]

Bringing this out from the investors thread:

Did it actually fly like in the video and was it a manned flight?

It did actually fly but it was empty, no passengers and just enough batteries for a few minutes of flight.

Are these guys going public ? -- anyway to invest in them ?

I would not touch this company with a ten feet pole. But that is just my opinion.

The biggest issue with Lilium is that the fundamental design parameters are flawed.

For more details, check this one out: Lilium: Weitere Experten unterstützen Kritik

In short, it has a very small "disk area" which is the total propellers area, so in order to do vertical takeoff and landing, the airflow speed going through these propellers needs to be very high. And no matter how much effort and analysis you put in this, it will turn out very noisy during takeoff and landing except maybe when flying empty.

Moreover, efficiency is directly proportional to disk area. So Lilium will have by far the least efficient eVTOL flying around. They will be lucky to get half the range of their competition.

Just look at all the serious eVTOLs contenders, such as Joby Aviation, Bell, Airbus or EmbraerX. They all have large propellers.

I supposed they call their contraption a jet for a reason, it will be so loud on takeoff and landing that their operation will be restricted outside of urban areas, such as large airports.

Look at their video on youtube:

They removed the soundtrack from the video. I wonder why?