Why battery-powered aircraft will never have significant range

[Mad MAC]

One point not covered by ZK-GEL accident report, did the battery fire result in the loss of all avonics, nav and radio. Possible worth considering ensuring atleast a radio will function after the loss of motive power due to battery fire.

 

[John.Roo]

One point not covered by ZK-GEL accident report, did the battery fire result in the loss of all avonics, nav and radio. Possible worth considering ensuring atleast a radio will function after the loss of motive power due to battery fire.

I don´t know electric Taurus construction, but more typical are two independent circuits.
12 V circuit for instruments and radio equipment + controller etc.
"Power" circuit with approx. 60-400 V (depending on propulsion type.
Of course you can make only one circuit using voltage converter. However I also prefer to have two circuits. Converter can be used to keep 12 V battery charged.

 

[Speedboat100]

I don´t know if CAA/LAA/FAA... would allow to jettison batteries + unless you have bateries exactly in airplane CG you should consider CG change after "drop out".

Right...CG is important issue here.

 

[blane.c]

From the words and pictures it seems that the fire did not cause structural failure. The by-product of the fire, the smoke and fumes were more of an issue. I have lost friends were smoke in the cockpit was a contributing factor, it will impair judgement.

 

[blane.c]

Thanks! Really interesting report.
Good reason to keep batteries away from cockpit (in the wings or in the front of firewall).

I know of fatal crash were smoke came in to cockpit past the firewall.

 

[Jay Kempf]

Must have been bad in the cockpit. The Taurus canopy is pretty big but I do believe it can be jettisoned. The cockpit is the entire forward fuselage lid. Not sure where the batteries are. I do know it has a ballast bottle up front so the electric version may have batteries up there as well.

If you haven't seen a runaway of a Lithium based battery you will not appreciate how dangerous that would be inside a fuselage. We had a large capacity battery let go due to a charging circuit problem. It burned a hole in the hangar floor looking like a large plasma cutter had been used. The arcing was going radial in all directions. The hangar owner was there by himself and he used a shovel to get it out the door just in time without injury. It was an eye opener. 18650 best in class batteries.

 

[Vigilant1]

I agree. I decided to keep the batteries outside. I even discussed with my structural engineer about possibility to jettison the batteries in case of an emergency. It would be rather easy to do in my design.

After you discussed it with your engineer, did you discuss the idea of dropping this flaming battery pack into the Finnish forests with your insurance company and your national aviation authorities? Let us know how that goes. There's a major utility in California that is at/near insolvency because their negligence started a big wildfire.

If my battery pack were on fire in flight, I'd certainly welcome the chance to jettison it and face the consequences later. It is a big earth down there, and most of it is not covered by orphanages and kindergartens. But:
1) Others, with different interests, may view the situation differently.
2) Everyone would agree it is much better to avoid this eventuality entirely.

 

[Speedboat100]

After you discussed it with your engineer, did you discuss the idea of dropping this flaming battery pack into the Finnish forests with your insurance company and your national aviation authorities? Let us know how that goes. There's a major utility in California that is at/near insolvency because their negligence started a big wildfire.

If my battery pack were on fire in flight, I'd certainly welcome the chance to jettison it and face the consequences later. It is a big earth down there, and most of it is not covered by orphanages and kindergartens. But:
1) Others, with different interests, may view the situation differently.
2) Everyone would agree it is much better to avoid this eventuality entirely.

No we did not discuss the dropping of the batteries into forests...we have thousands lakes.

 

[blane.c]

Dale Kramer put the batteries in the wings of his electric Lazair. Considering it some I do not like a blow torch next to the spar and I do not like the idea of losing wing skin but I like very much that the "problem" is outside the cockpit.

I can remember looking out and seeing flames rolling over the engine cowling on the DC-4 and I think how much worse the experience would have been if the flames were about the fuselage somehow especially in front rolling over a boot cowl. At least with the problem out on the wing you could focus on the two things in the world that mattered most in the world at the time, putting the fire out and or being on the ground.

 

[Vigilant1]

No we did not discuss the dropping of the batteries into forests...we have thousands lakes.

The plan is to glide the flaming unpowered aircraft to a lake? It just keeps getting funnier.

When that battery catches fire, if the pilot has the ability to dump it I assure you the dumping will occur with very little concern about the location of the nearest lake.
Let your insurance company know they could be on the hook to find and recover a battery pack from a lake.

 

[Speedboat100]

The plan is to glide the flaming unpowered aircraft to a lake? It just keeps getting funnier.

When that battery catches fire, if the pilot has the ability to dump it I assure you the dumping will occur with very little concern about the location of the nearest lake.
Let your insurance company know they could be on the hook to find and recover a battery pack from a lake.

No the plane can land on water, but with outstanding glide ratio can always find a field.

 

[Toobuilder]

No the plane can land on water, but with outstanding glide ratio can always find a field.

Not sure you're appreciating the issue here:

you have a thermal runaway and fire on board with essentially a 500 pound magnesium flare in the belly of the aircraft. You have 10 seconds to fix the problem or exit the aircraft...

The "plan" is to glide to a lake?

 

[Hephaestus]

The final report has the important picture... The seatback was scorched, as was the canopy. Batteries were ejected during impact sequence, so this wasn't post crash damage.

So the pilot had 500celcius/923f on his back after the 'thermal event' started. We know how hot a small glider cockpit can get just in the sun - add crazy heat source + blinding (lipo fires are nasty, its like tear gas for your eyes/lungs) smoke. The pilot was basically along for the ride as soon as those packs lit off based on the scorching + add in some melting/burning composites.

skip to a minute in for the poof.

I think speedboat is probably referring to a previous comment I made on a previous electric thread. Discussing this with my local fire captains - they'd prefer a wildland fire + separate off airport landing site vs a fatal plane crash/fire. May slightly differ if you're operating over dense urban areas. But it's a big earth - the likelihood is a burning pack separating and injuring others is up there with the risk of someone being struck by a re-entering satellite.

California/USA legal issues is a whole different can o worms.

 

[Toobuilder]

The Edison/PG&E wildfire issue in California is a "real thing". Im not going to comment on "fault" in this case, but dropping a burning LiPo battery (even RC model sized) in much of the "big earth" areas of the US SW will most certainly result in big fire, destruction and death. Gasoline is much safer in this regard. Dumping fuel generally only results in evaporation or combustion BEFORE reaching the surface. Dropping 500 pounds of dense, persistent fuel into a forest is a different paradigm.

 

[Speedboat100]

Certainly you have to choose where to drop them.

 

[Dusan]

Sorry for the glider pilot, we cannot do anything but to learn from such tragic events. It seems that electric aircraft needs to develop means for venting the battery fire outside the cockpit, and have enough fireproof protection to enable the aircraft to reach ground landing site safely. Taking into account that battery stored energy is 40 times less than gasoline, the fire is less energetic than fuel fire, fact demonstrated by countless tesla fires.

 

[Hephaestus]

Certainly you have to choose where to drop them.

You're not realizing they need to automatically eject immediately (like I said in the other thread - probably needs to be on fire links). There's really no delay option unless you're in a pod type install with isolation from critical structure. That said - 14' kevlar/nomex parachutes are a thing in the rocketry world - but same issue as the BRS, if you're in the pattern, they're unlikely to open...

 

[blane.c]

I really don't think the pilot choosing where to drop a burning pile-"O"-Lithium during an emergency is the time the decision should be made. If the batteries are drop-able then the decision has been made and it has to be suitable to drop them any time for any reason anywhere.

I doubt the dropping option will be deemed "politically correct" by all. And few would like to be responsible for the injury or death of another however unlikely.

A Nomex nest?

Fires were more common on early aircraft, detection and protection were standardized, ejection of the engines was not a practice. Dumping fuel was practiced but it has been proven that fuel dumped over 45mph will be to lean to burn and will further dissipate.

Lithium may continue to burn once ejected? And is not likely to dissipate?

Batteries should be placed so as not to cause catastrophic damage during a fire and also so as to not fill the cockpit with smoke/vapors. This should be at the expense of extra weight to the extent necessary.

 

[Toobuilder]

Certainly you have to choose where to drop them.

Easy to say from the comfort of your kitchen.

Lets say it again - you are at 7500 feet AGL, you detect a thermal runaway of your 500 pound battery pack, you have 10 seconds until structural failure, battery ejection or bailout.

Please describe your next action.

 

[Bille Floyd]

Certainly you have to choose where to drop them.

I believe it's , what people here are trying to point out to
you ; Ya don't have time to decide where to drop them :
1) The burning battery must leave Now .
2) Or the occupant must leave the burning plane, (Now)
not when it becomes convenient.

Bille