Why battery-powered aircraft will never have significant range

[Speedboat100]

My craft has 100 lbs at most. Finland has least people pro sqm2 in Europe and craft is not allowed to fly on densely populated areas. I see no danger there. Situation cannot come in seconds as you control the temperatures.

 

[blane.c]

I think the batteries should be placed so that the craft and occupants can continue flight at least for a predetermined period of time. The I have to jump through my * and do something that may be stupid mentality should be thought about a little?

 

[Hephaestus]

If you're at an altitude that precludes getting on the ground within a minute - the packs coming out whether you want it to or not.

1000f - explosive degassing. You're talking an uncontrolled oxy/acetylene torch - it's going to liberate itself pretty much no matter what you do. This is an issue with all electric aircraft that use lithium batteries.

The question is what do you do to prevent collateral damage along the way.

 

[Speedboat100]

I think the batteries should be placed so that the craft and occupants can continue flight at least for a predetermined period of time. The I have to jump through my * and do something that may be stupid mentality should be thought about a little?

Yes the batteries ought to be in a metal container..for sure.

 

[Vigilant1]

Total area of Finland: 31 million hectares
Forestry land in Finland: 26 million hectares.
Lake, river area of Finland: 3.3 million hectares

If it is physically possible to drop the flaming lithium batteries and anyone believes they would delay that decision for even a moment, I will say right now they are not fully appreciating the situation as it will be.

Very sorry for the pilot of that Pipistrel motorglider. There may be a worse way to die in an airplane, but I can't imagine it.

 

[blane.c]

Yes the batteries ought to be in a metal container..for sure.

I doubt there is a metal that can survive the temperatures involved.

 

[blane.c]

Temperature of burning LIPO batteries

Years of working in machine shops working with exotic metals including Magnesium and Titanium taught me the basics of metal fires. Run. If you are lucky they can save the building. Or the building next door. Go ahead & wrap your to burn materials in inconel. Now you have a bomb...

www.homebuiltairplanes.com

 

[jedi]

Is battery ejected but restrained by a 20 foot lanyard a possibility?
Could possibly help with the CG issue also.

 

[Jay Kempf]

Large battery comes out of wherever it is installed, wind catches it, lanyard halts its fall. The rest is basically a partial chute deployment scenario that doesn't end well. The only positive parts is you might not burn to death in the first few seconds. The ending is the same.

 

[Hephaestus]

Is battery ejected but restrained by a 20 foot lanyard a possibility?
Could possibly help with the CG issue also.

A burning pendulum swinging below your aircraft...

 

[jedi]

A burning pendulum swinging below your aircraft...

A burning pendulum swinging below your aircraft...is much better than a burning aircraft tied to my but.

It is even better when I have a disconnect button or can let it burn off.

 

[Jay Kempf]

Not really. It is a huge bob weight with big surface area that will just toss you out of control.

The question is: two choices, burn to death or crash to death...? Pick one.

Not sure how you are going to auto disconnect a 200 amp bus worth Kilowatts if you want to drop it. Explosives?

 

[blane.c]

I wonder if some genius could figure how to have something like this pop out and float it away?

 

[Hephaestus]

Not sure how you are going to auto disconnect a 200 amp bus worth Kilowatts if you want to drop it. Explosives?

In the oilfield its fairly easy to find large guage electrical connectors with break-away/tear-away capabilities. The electric shovels and draglines tended to have some massive ones. But there's going to be a learning curve with those too, like any connector there's a maintenance issue to address.

The system integration of the whole package is no small feat to put together. I wouldn't want to do it.

 

[Jay Kempf]

Those industrial disconnects I am sure don't have the electrical requirements that these electric aircraft have. That sort of amps tends to weld contact. Plus the force, weight of industrial equipment to force the separation is probably orders of magnitude a battery on the end of a short 3 wire rope. Maybe not but most probably. The order of these sorts of aircraft connections are snap together or large stud and nut gold plated connections. The electrical specs of these power buses always catch me by surprise. High volts give lower amps but the amps are high too for as small as most of this stuff is.

 

[Hephaestus]

Those industrial disconnects I am sure don't have the electrical requirements that these electric aircraft have. That sort of amps tends to weld contact. Plus the force, weight of industrial equipment to force the separation is probably orders of magnitude a battery on the end of a short 3 wire rope. Maybe not but most probably. The order of these sorts of aircraft connections are snap together or large stud and nut gold plated connections. The electrical specs of these power buses always catch me by surprise. High volts give lower amps but the amps are high too for as small as most of this stuff is.

No question - like I said the systems integration would make my head hurt. And you've got to test everything because you need to know what's happening to volts/amps as the packs burning too... Same with cells swelling and obstructing.

I've seen some pictures where it looks like there's andersen connectors being used near the packs - but so-far nothings really standardized, so it's all guesswork. Or maybe that's just the charging connector?

Fun job for someone else to figure it out

 

[BBerson]

I would suggest a hinged trap door on the bottom that would hold and retain the batteries about 24" below but rigid.
The main blow torch event lasts a minute or something. I watched an RC model burn. Vent it down.

 

[Jay Kempf]

I would suggest a hinged trap door on the bottom that would hold and retain the batteries about 24" below but rigid.
The main blow torch event lasts a minute or something. I watched an RC model burn. Vent it down.

That is an interesting thought. Dump down out the bottom of the fuselage but fixed and with a blast shield. Air is the best coolant and insulator at that point. The 4 bar mechanism or whatever would have to be shielded from the blow torch but that is possible. What is not possible to allow is that the battery array or at least most of its mass falls off. Two reasons for that: first being CG and second being dropping the blow torch for any reason. Let it burn out and control it.

Really clever thought BB...

When I saw the collateral damage of the 2kw pack of 18650 batteries it amazed me. There is a lot of energy stored in these tiny packs that we take for granted every day when we use an HD cell phone.

 

[BBerson]

And the battery doesn't need a complex connector. It could stay connected and might still work as you find a crash site.

 

[Hephaestus]

I would suggest a hinged trap door on the bottom that would hold and retain the batteries about 24" below but rigid.
The main blow torch event lasts a minute or something. I watched an RC model burn. Vent it down.

But an rc pack is typically few cells...


6s74p...

That's 444 batteries to cook off. And it's usually heat damage that sets the later ones off. This is why relight is such a headache. Watch some tesla fires on youtube.