49 replies to this topic

[voyagerB]

Since the UBER Elevate Summit in April this year, more OEMs said they would develop eVTOLs, aircraft that can take off and land vertically and that use electric power. Among them AgustaWestland, Aurora, Airbus. Embraer. The argument for eVTOLs is as follows.

 

1. If aviation authorities will allow parcel delivery drones, why not beef-up the rotors and airlift passengers? Electric rotor technology is constantly evolving (already past the 5 kW per 1 kg own weight threshold), so are lightweighting and battery tech.

 

2. If we expect cars to ‘2D-maneuver’ autonomously through dense city traffic... then it should be less of a problem to have rotor-equipped vehicles auto-pilot themselves through the air, where there’s lots of 3D space to maneuver. 

 

3. eVTOLs are safer than ICE-propelled helicopters. They are less complex, have less mechanical parts, have no variable propeller settings (like a helicopter has). eVTOLs will be cheaper to operate, and will not require a pilot (license) in 5 years time. 

 

4. Change of regulations is up to aviation authorities of course. Adapting them will work as an enabler of one of the most exciting, new industries (same with developing self-driving cars). Generally, governments don't want to miss out on them.

 

What say you?

[chris pochari]

E VTOLS, Lilium etc are constrained by the low energy density of lithium ion batteries. So any large job like carrying people on a charter trip or tour is going to be very difficult for an electric VTOL unless lithium ion energy density is dramatically improved. Electric can work for very short distance UAV application, photoshooting etc. 

https://ibb.co/kF3gZa click here to see the comparison. 

Lithium ion energy density is 100 times less than kerosene/JET A

here's an interesting video

so far electric only provides disadvantages over turbine power. Batteries have a LONG way to go before they can be competitive with fossil fuel. Some person in Palo Alto equipped a Robinson R44 with a 1200lb battery, it flew for 12 minutes I think. 

Technological evolution only happens if the technology being replaced is inferior to the new technology, like steam to diesel and piston to turbine. Going from Turbine, or piston, to electric is a downgrade, less range, more weight and less payload? Helicopters, or Quadcopters are the least efficient form of air transport, requiring the most energy to generate lift, if airplanes haven't been electrified yet than helicopters have along way to go.

I did a hypothetical conversion of a cessna 172 from gas to electric, if you were to take the space used to store the fuel, and replace it with high end lithium batteries, not exceeding the weight of the fuel (because we don't want to lose payload) you would get only 6% of the range of the gas powered airplane. Now do that with a helicopter and see what you get, it will be even worse. To get the same range as the original airplane you would need 14000lbs of batteries!!!!! I heard one guy say for a 747 to take off powered by batteries you need need 2 additional 747's full of batteries. Not happening, And that's fixed wing!

[r22butters]

What say me?

I used to deliver for Fedex, I also used to take a semi over to Amazon to pickup in bulk, and the sheare volume of packages that go through the system every day makes drone delivery so, so, impractical!

Plus there will probably be a clever hoodie type who follows the drone waiting for it to drop its package so he can then snatch it and run! At least I could hide the box, lets see a drone do that!

Even out in the middle of butt-crack nowhere you'd still need a army of drones,...it ain't gonna happen!

As for passengers, I'll stick with the 737 ride to Vegas!

,...oh' yeah, and a bunch of people flying around with no license (and thus no training) yeah, that's an awesome idea!

[voyagerB]

E VTOLS, Lilium etc are constrained by the low energy density of lithium ion batteries. So any large job like carrying people on a charter trip or tour is going to be very difficult for an electric VTOL unless lithium ion energy density is dramatically improved. Electric can work for very short distance UAV application, photoshooting etc. 

https://ibb.co/kF3gZa click here to see the comparison. 

Lithium ion energy density is 100 times less than kerosene/JET A

Click here to watch Allan Epstein from P&W explain https://www.facebook...?type=3. So far electric only provides disadvantages over turbine power. Batteries have a LONG way to go before they can be competitive with fossil fuel. Some person in Palo Alto equipped a Robinson R44 with a 1200lb battery, it flew for 12 minutes I think. 

Technological evolution https://en.wikipedia...gical_evolution only happens if the technology being replaced is inferior to the new technology, like steam to diesel and piston to turbine. Going from Turbine, or piston, to electric is a downgrade, less range, more weight and less payload? Helicopters, or Quadcopters are the least efficient form of air transport, requiring the most energy to generate lift, if airplanes haven't been electrified yet than helicopters have along way to go.

I did a hypothetical conversion of a cessna 172 from gas to electric, if you were to take the space used to store the fuel, and replace it with high end lithium batteries, not exceeding the weight of the fuel (because we don't want to lose payload) you would get only 6% of the range of the gas powered airplane. Now do that with a helicopter and see what you get, it will be even worse. To get the same range as the original airplane you would need 14000lbs of batteries!!!!! I heard one guy say for a 747 to take off powered by batteries you need need 2 additional 747's full of batteries. Not happening, And that's fixed wing!

The thing is that fixed-wing requires a landing strip. If we expect next-gen aerial vehicles such as air taxis (UBER does) to really work, then VTOL will be paramount. Next issue is (indeed like you suggested) how to make flight itself more efficiently. Some aviation companies pursue airplane-like flight with swiveling thrusters to do the VTOL party trick. Here are the concepts that are being worked on:

 

[chris pochari]

The thing is that fixed-wing requires a landing strip. If we expect next-gen aerial vehicles such as air taxis (UBER does) to really work, then VTOL will be paramount. Next issue is (indeed like you suggested) how to make flight itself more efficiently. Some aviation companies pursue airplane-like flight with swiveling thrusters to do the VTOL party trick. Here are the concepts that are being worked on:

 

I'm familiar with most of these designs, They have been in the news a lot! I get a little worried when Uber, a taxi app company get's in the aviation business. But overall I think electric VTOL, Fix wing or any type of electric powered aircraft will prove to be very difficult. Check this out

http://energyskeptic.com/2013/why-arent-there-battery-powered-airplanes/ 

A 200-seat airplane weighs about 115 tons at take off.

About a third, or 38 tons of that weight is the kerosene fuel.

The other 77 tons are the passengers, their luggage, and the airplane itself.

An electric, battery-powered airplane would require nearly 3,000 tons of lithium-ion batteries – the batteries would weigh 39 times more than the plane, passengers, and their luggage.

Nor would fuel cells do much better.
 

Source: Mark Schrope. 6 Nov 2010. Fly Electric. New Scientist.

[voyagerB]

@chris pochari

 

The pictures I posted are all 2-seater designs. The Ehang is even a single seater.

I am not talking about electric passenger planes like Tesla and Wright Electric are contemplating.

[chris pochari]

 

 

Skip the motors, batteries, fuel cells and fuel tanks. With 200 seats, eliminate the under seat luggage & install pedals. "This is your captain speaking, we are ready for take off, everyone pedal as fast as you can"

 

"we have reached our cruising altitude now, you tired passengers can now take break"

 

"we are starting our decent now, ALL of you passengers can stop now & we thank you for peddling with us today"

Yup

[Fred0311]

Pokey isn't that what Spirit already does?

[Eric Hunt]

 

 

Will eVTOL take over the commercial small-helicopter market?

 

 

No.

[r22butters]

Enough already! We already know what the future's going to look like!




,...and electricity, magnetism, and gravity are all God's farts!

[Whistler]

Eventually.  But we are all safe.  so are our children if they want to become pilots I think. It will take a generation or more before these technologies become sophisticated enough to truly be game changers.  Electronic cars are just NOW becoming a viable alternative.  The first electric car on the market came out in 1884.  Since then numerous iterations have started and failed over the years.  It takes a lot more time for ideas to succeed in reality than they do in our imaginations.  The world is moving faster than ever before... but still not as fast as we think it is.  

 

still, it's important to be future minded.  lest we fall victim to thinking we are as untouchable as the railroad, coal, motor city, etc... history is rife with examples of people who believed their means of making a living would go on forever.  always have a plan B.

[My Rotor]

I agree with the above.  The elusive new energy source that will allow some of these ideas to become reality still remains undiscovered.

 

In the meantime, Uber's vision to have 1 to 4 people transported across town by a lightweight airborne vehicle may succeed with electric power.

[voyagerB]

New battery technology will be decisive, sure. Below a sort of checklist. IMO, there's terrain that can be gained on the conventional chopper. It's a debate or say prospect that bears similarities with that of the conventional gas-driven cars vs self-driving EVs.

 

[Eric Hunt]

Voyager, your wishlist is open to contention:

 

1. Safety. Hasn't been proven yet. The mechanical faults of a pilot-controlled piston or jet-powered helicopter are all applicable to an electric auto-pilot machine.

 

2. "No pilot licence needed in 3-5 years." Laughable. How fast do you think the regulators are going to move on this??

 

3. Range. Hasn't been proven.

 

4. Closer to your point of departure. But if a piloted helo can't land anywhere near your house (and certainly not on the front street) why does anybody think the regulator will permit an unpiloted machine to do so? Local councils can forbid a landing.

 

5. Environment (emissions). Yes perhaps on emissions.

 

6. Reliability. Not proven yet. Mobile phone batteries burst into flames, these might too.

 

7. Hourly costs. Perhaps, the overhaul cycles on an electric motor might be lower, but there are still the checks and overhauls on rotor heads, transmissions, and there WILL be some serious checks on the autopilots to make sure they are still operating to Isaac Asimov's Robot Rules.

 

8. Space efficiency. Not proven yet, show us some REAL machines capable of doing the job.

 

9. Noise level. The noise from multiple small rotors is more than one larger rotor. And there is a thing called "perceived noise", whereby ground observers see a helicopter, immediately flooded with thoughts of privilege, rich person, I can't afford that, therefore it must be noisy and I MUST complain to somebody.

 

10. regulations. At last, a correct response. Nobody has created any regulations, but be assured they will be draconian.

 

The comparison to self-drive cars is a bit dubious - cars drive on roads which have physical boundaries, known by GPS and recognisable by cameras, and are only 2-dimensional. Get into the air and suddenly there are no edge markings for the cameras to see, and the radar-cruise-control has to look in WAY more directions than just straight ahead.

 

Will the altitude be determined by pressure altimeters, or radar altimeters, or by GPS? Many ways to bump into somebody while thinking you are at the correct cruising level.

 

We will not see these in any foreseeable timeframe, despite what Amazon and Uuuuuber say.

[Hobie]

Don't forget the wires.  There isn't a 100% success wire detection system now.  Maybe this would be a side benifet as drone tech evolves.  

 

As a kid, we shot our BB guns and slingshots at anything that moved. Can't see that changing when a Amazon package flys overhead. 

[Nearly Retired]

Don't forget the downwash.  Everybody always forgets the downwash.  The smaller the props, the higher (and more potentially damaging) the downwash velocity.

[voyagerB]

Don't forget the downwash.  Everybody always forgets the downwash.  The smaller the props, the higher (and more potentially damaging) the downwash velocity.

 

So, how come German Lilium recently received 90 million USD from investors? Experts I talked to mentioned the same reason (too small thrusters) to make it fly for any interesting range, with enough batteries and people onboard. I calcaluated that the disk loading must be around 378 lb / ft2. 14 times as much as the Osprey's. Don't know about the downwash, but it must be one helluva screamer!

 

[Eric Hunt]

 

 

So, how come German Lilium recently received 90 million USD from investors?

Because people like you have believed the "dream" because they have no concept of the difficulties of making it happen. Yeah, bring on the Jetsons, here's a thousand bucks, and here are 90,000 other believers with their $1000.

 

And you probably believe that because the earth is flat, these pilot-less drones can make it to Europe.