Future of aviation, or flash in the pan??

On 1/24/20 9:58 AM, Steve Leonard wrote:
Good to run those tests at night so you can see the fire sooner.


Good point. But if the main battery ever lit up (8200 lbs of
lithium-cobalt) it ought to make quite a bonfire.

On Friday, January 24, 2020 at 9:21:41 AM UTC-8, kinsell wrote:
On 1/24/20 9:58 AM, Steve Leonard wrote:
Good to run those tests at night so you can see the fire sooner.


Good point. But if the main battery ever lit up (8200 lbs of
lithium-cobalt) it ought to make quite a bonfire.

But the weight efficiency of those LiCo bats is phenomenal. Let's see, 900KWH is the same energy in......154 lbs of Jet-A. Not sure how much energy is in 8200 lbs of LiCo if you light it on fire though.

On Friday, January 24, 2020 at 11:19:09 AM UTC-8, jfitch wrote:

...Let's see, 900KWH is the same energy in......154 lbs of Jet-A. Not sure how much energy is in 8200 lbs of LiCo if you light it on fire though.

Fully-charged lithium battery fires generally release as heat 1.6 times the stored electrical energy over the course of the runaway. So it'd be about like 250 lbs of Jet-A.

On 1/24/20 1:07 PM, Bob Kuykendall wrote:
On Friday, January 24, 2020 at 11:19:09 AM UTC-8, jfitch wrote:

...Let's see, 900KWH is the same energy in......154 lbs of Jet-A. Not sure how much energy is in 8200 lbs of LiCo if you light it on fire though.

Fully-charged lithium battery fires generally release as heat 1.6 times the stored electrical energy over the course of the runaway. So it'd be about like 250 lbs of Jet-A.


What ever the number is, it can pack a punch. Relevant stuff starts
about 5:00


https://www.youtube.com/watch?v=rvkEpstd9os&t=1326s

On Friday, January 24, 2020 at 12:21:41 PM UTC-5, kinsell wrote:
On 1/24/20 9:58 AM, Steve Leonard wrote:
Good to run those tests at night so you can see the fire sooner.


Good point. But if the main battery ever lit up (8200 lbs of
lithium-cobalt) it ought to make quite a bonfire.

Somehow flying that thing makes me think of the guy riding the H-bomb in Doctor Strangelove.

I do hope they find safer battery chemistries before long. LiFePO4 is much safer, but the energy density is even poorer and the cost even higher.

On 1/24/20 8:07 PM, wrote:
On Friday, January 24, 2020 at 12:21:41 PM UTC-5, kinsell wrote:
On 1/24/20 9:58 AM, Steve Leonard wrote:
Good to run those tests at night so you can see the fire sooner.


Good point. But if the main battery ever lit up (8200 lbs of
lithium-cobalt) it ought to make quite a bonfire.

Somehow flying that thing makes me think of the guy riding the H-bomb in Doctor Strangelove.

I do hope they find safer battery chemistries before long. LiFePO4 is much safer, but the energy density is even poorer and the cost even higher.


Good analogy. That was Slim Pickens, wasn't it?

Someone at Eviation said the thing is (or was) basically a battery with
a picture of an airplane painted on it. I wouldn't have guessed they
could get 8200 lbs of lithium battery in there and still have room for
px. It's am ambitious project, 600 mile range, but at some point
reality starts to rear its ugly head.

On Fri, 24 Jan 2020 20:27:45 -0700, kinsell wrote:

On 1/24/20 8:07 PM, wrote:
On Friday, January 24, 2020 at 12:21:41 PM UTC-5, kinsell wrote:
On 1/24/20 9:58 AM, Steve Leonard wrote:
Good to run those tests at night so you can see the fire sooner.


Good point. But if the main battery ever lit up (8200 lbs of
lithium-cobalt) it ought to make quite a bonfire.

Somehow flying that thing makes me think of the guy riding the H-bomb
in Doctor Strangelove.

I do hope they find safer battery chemistries before long. LiFePO4 is
much safer, but the energy density is even poorer and the cost even
higher.


Good analogy. That was Slim Pickens, wasn't it?

Someone at Eviation said the thing is (or was) basically a battery with
a picture of an airplane painted on it. I wouldn't have guessed they
could get 8200 lbs of lithium battery in there and still have room for
px. It's am ambitious project, 600 mile range, but at some point
reality starts to rear its ugly head.

With a big motor on each wingtip (in the photos they look bigger than the
rear motor) I do wonder about its handling if one of the wingtip engines
fails/gets hit by a goose, etc., or do they just shut down the other
wingtip motor and land wherever possible.



--
Martin | martin at
Gregorie | gregorie dot org

On 1/25/20 2:54 AM, Martin Gregorie wrote:
On Fri, 24 Jan 2020 20:27:45 -0700, kinsell wrote:

On 1/24/20 8:07 PM, wrote:
On Friday, January 24, 2020 at 12:21:41 PM UTC-5, kinsell wrote:
On 1/24/20 9:58 AM, Steve Leonard wrote:
Good to run those tests at night so you can see the fire sooner.


Good point. But if the main battery ever lit up (8200 lbs of
lithium-cobalt) it ought to make quite a bonfire.

Somehow flying that thing makes me think of the guy riding the H-bomb
in Doctor Strangelove.

I do hope they find safer battery chemistries before long. LiFePO4 is
much safer, but the energy density is even poorer and the cost even
higher.


Good analogy. That was Slim Pickens, wasn't it?

Someone at Eviation said the thing is (or was) basically a battery with
a picture of an airplane painted on it. I wouldn't have guessed they
could get 8200 lbs of lithium battery in there and still have room for
px. It's am ambitious project, 600 mile range, but at some point
reality starts to rear its ugly head.

With a big motor on each wingtip (in the photos they look bigger than the
rear motor) I do wonder about its handling if one of the wingtip engines
fails/gets hit by a goose, etc., or do they just shut down the other
wingtip motor and land wherever possible.




Slick presentation from Paris Air Show he

https://simpleflying.com/eviation-al...tric-aircraft/

Quick answer is they intend to shut down opposite motor in case of
trouble with one wingtip. Supposedly they can takeoff on just the rear
after V2.

Like Harbour Air, making claims of really fast recharge times. Fly for
two hours, recharge in one. Good way to fry your batteries, maybe this
thing uses copious quantities of snake oil for cooling.

Harbour Air CEO was quoted in one of the articles as saying there are no
constraints in how fast you charge lithium batteries, just pump in more
current if you want a faster charge. I wonder if these guys actually
believe their own hype? Scary.

When you have so much battery capacity. You have a lot power to spare (discharging or charging). If they use the full capacity in two hours without counting the reserve the rate of discharge is 0,5C. And the chare rate is 1C. That is not much workload for most of the popular cells. But you need a extremely big super charger.

Emir Sherbi wrote on 1/25/2020 8:07 PM:
When you have so much battery capacity. You have a lot power to spare (discharging or charging). If they use the full capacity in two hours without counting the reserve the rate of discharge is 0,5C. And the chare rate is 1C. That is not much workload for most of the popular cells. But you need a extremely big super charger.

Yes, for example, some of the Teslas can "take about 20 minutes to charge to 50%,
40 minutes to charge to 80%, and 75 minutes to 100% on the original 85 kWh Model S".

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1