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Reliability of ELECTRIC airplanes in question

FAA Stance on Electric Airplanes: No Passengers | Flying Magazine

FAA says NO to passengers in electric airplanes at this point (even though they aren't in the US yet).

What says the engineer types on the forum.
Are electric airplanes safe(er)?
Do you think they will make it in the market when they are available to the general public?

I'm not an engineer but a big follower of the electrification (word?) of the automobile. I read that brief article too and thought it was interesting. In theory, an airplane with an electric motor should be a lot more reliable than a recip engine, but I guess until the "new" technology (battery and engine) gets a track record in aviation, I can see why they might want to proceed cautiously.

Taurus Electro G2: I'm not sure how many people are willing to plug in the thing for five hours to get one 4000 foot self launch.

What would Elon Musk do?

Quote:

Originally Posted by FlyJSH (Post 1613513)

Taurus Electro G2: I'm not sure how many people are willing to plug in the thing for five hours to get one 4000 foot self launch.

Why not? Who flies an airplane for 24hrs a day?

The engines should be super reliable, and should have great performance at higher altitudes.

It's the batteries I'm worried about. Battery technology just isn't where it needs to be for me to even consider an electric car yet.

Engines are good to go, better power density than pistons and probably turbines. Probably better reliability when built to appropriate standards.

Batteries can be reliable, compact, or cheap...pick one or maybe two at best.

I'm sure you could make a lithium battery/electric motor combo which would far exceed the reliability of current propulsion systems. But it would be very expensive.

For example I suspect that lithium batteries need a temperature and pressure controlled environment...basically the battery needs is own pressure container with thermal controls. They also probably need extreme quality control in design and construction, and probably active vibration damping. On top of that you need containment that can withstand a full runway, and at least two parallel units for redundancy. It can be done, but it won't be cheap, or very compact/light.

Quote:

Originally Posted by threeighteen (Post 1621530)

It's the batteries I'm worried about. Battery technology just isn't where it needs to be for me to even consider an electric car yet.

Why not? What battery technology do you want to see before you buy an electric car?

Quote:

Originally Posted by rickair7777 (Post 1621661)

For example I suspect that lithium batteries need a temperature and pressure controlled environment...basically the battery needs is own pressure container with thermal controls. They also probably need extreme quality control in design and construction, and probably active vibration damping. On top of that you need containment that can withstand a full runway, and at least two parallel units for redundancy. It can be done, but it won't be cheap, or very compact/light.

I would assume that if you wanted any significant amount of battery capacity, they would be placed in the wings. That would provide enough vibration protection. Temperature protection....air cooling might be pretty sufficient considering how fast aircraft fly. 1/2 the battery capacity in each wing, there's the parallel redundancy. Not sure about needing a pressure container. The batteries are sealed. Full runaway protection....yeah that would be a concern I guess. There are lots of electric cars driving around, and I have only heard of two or three thermal runaways. All were caused by some sort of catastrophic penetration of the battery case caused by the car being crash tested, being involved in a car accident, and a pretty good chunk of road debris. Perhaps they could engineer some sort of venting if a segment of the cells over-pressurizes, similar to what Boeing did with the 787.

Quote:

Originally Posted by globalexpress (Post 1621848)

Why not? What battery technology do you want to see before you buy an electric car?

I would assume that if you wanted any significant amount of battery capacity, they would be placed in the wings. That would provide enough vibration protection. Temperature protection....air cooling might be pretty sufficient considering how fast aircraft fly. 1/2 the battery capacity in each wing, there's the parallel redundancy. Not sure about needing a pressure container. The batteries are sealed. Full runaway protection....yeah that would be a concern I guess. There are lots of electric cars driving around, and I have only heard of two or three thermal runaways. All were caused by some sort of catastrophic penetration of the battery case caused by the car being crash tested, being involved in a car accident, and a pretty good chunk of road debris. Perhaps they could engineer some sort of venting if a segment of the cells over-pressurizes, similar to what Boeing did with the 787.

I suspect (don't know) that li batteries are susceptible to small mfg defects which might be aggravated by vibration or pressure changes. Tight control of the physical environment, and mfg tolerances, might make them reliable enough to get certified for that sort of heavy duty. I don't think the 787 batteries had a gross design or mfg defect, I think they just turned out to be more sensitive to the operational environment than expected.

At the energy density and quantity required for propulsion it would hard to contain a runaway without impractically heavy structures.

Quote:

Originally Posted by globalexpress (Post 1621848)

Why not? What battery technology do you want to see before you buy an electric car?

Lower weight, better capacity, longer service life.

Batteries are still heavy when they're drained. Fuel has the magical property of not weighing down the aircraft once it's used.