TSLA Market Action: 2018 Investor Roundtable

[malcolm]

a single sock is enough to stop it from being able to enter the house.

Yeah, but you run the risk of losing your House Elf.

 

[CHGolferJim]

Whew, over past 4 days caught up on 2 months of unread posts in this thread (okay, I skipped a few pages). Coincidentally (NOT), yesterday I converted a smallish Beneficiary IRA to 100% TSLA to increase my stake by 15% — got in at $343.xx. Trading shares converted in my mind to core. Happy Thanksgiving to all you longs.

 

[lascavarian]

On a steep enough descent, a prop-driven electric aircraft can regen, yes.

Interesting thread. I am assuming that the only form of thrust for electric planes would be props. At high altitude it would seem the lower air density would require substantial compensation for props to generate thrust where lift is decreasing with air density - I think at least.

 

[Unpilot]

EHD thrusters actually are a common garage project. Particularly popular among the antigravity-conspiracy crowd, which calls them "Lifters" The MIT team's work is much more professional, of course, with actual calculated optimal currents, voltages and geometries, which is what let them (barely) carry their own power supply for the first time.

CFD genetic algorithms for evolving arcjets, though... yeah, not many people seem to do that for fun

Yeah I just fly them...my engine knowledge is summed up like this ...suck ,squeeze, bang ,blow.

 

[mongo]

View attachment 354860

I see something different on my desktop:
Edit: Proving my point, I didn't notice at the bottom of the page in the black area is the actual pricing:

Different? That is the same as the 2nd and 3rd zoomed in shots I put up. The * is before the prices, not hidden at the bottom, the bottom has before and after savings right next to the 'Next' button you must press to continue. Final page is

Seems pretty clear to me.

 

[KarenRei]

Interesting thread. I am assuming that the only form of thrust for electric planes would be props.

Not necessarily. As mentioned, I'm messing around with CFD sims of electric ram-arcjets. Traditional arcjets are a means to augment the thrust on a cold gas or monoprop rocket thruster - but the same principle applies to a ramjet equivalent. Very similar to a ramjet, except that the energy input comes from an electric arc rather than combusting fuel. Another variant would involve inductive plasma heating - less potential issues with ozone and electrode wear, but more challenging in terms of heat removal and weight. While I'm not nearly to this point yet, I'm thinking an arcjet could be maintained in an isotropic glow discharge mode with SiC mosfet arrays adjusting the current flow to various portions of the electrodes.

Electric planes can also, at low speeds, theoretically (and now demonstrably) be flown with EHD thrusters - but note the thrust density issues described above.

At high altitude it would seem the lower air density would require substantial compensation for props to generate thrust where lift is decreasing with air density

Props are rotating wings. Just like wings, they work in sparse air, but the optimal shapes differ. Most notably, the optimal chord length is longer relative to the thickness. Here's the prop on the XF-88B prop research prototype - note how thin the blades are:

It's the only prop on an operational aircraft to be flown steady-state in a thrust-providing manner at faster than the speed of the sound. It wasn't primary propulsion for the aircraft (the aircraft had two jet engines as well), but it was nonetheless operating and providing thrust in that environment.

Another technique that's advantageous at high speeds is, like for all wings, a backwards sweep, in order to reduce wave drag.

 

[jbih]

Next-generation solid-state batteries in production in China - Xinhua | English.news.cn

Solid state batteries now in production. More than 400Wh/kg. Expected manufacturing capacity 0.1 GWh now, 0.7 GWh in 2020.

 

[KarenRei]

Next-generation solid-state batteries in production in China - Xinhua | English.news.cn

Solid state batteries now in production. More than 400Wh/kg. Expected manufacturing capacity 0.1 GWh now, 0.7 GWh in 2020.

Yep. I expect them to be very pricey. Their main market will probably be aerospace (both aircraft and spacecraft), where mass density is critical.

Wonder what their cycle life is like... Also, if they're using metallic lithium, I really want to see how they fare in safety testing.

 

[Artful Dodger]

I think that when companies talk about hybrid planes, they are really talking about plug-in hybrids. A key issue in aviation is maintenance. Engine maintenance requirements would depend on hours of use of the engines, so a plug-in hybrid system that reduces engine hours would help reduce maintenance, while a regular hybrid system would not.

There's a very significant challenge in aviation that's leading to more focus on hybrids: mandatory fuel requirements.

The fuel requirements are such that for the shorter flights that electric airplanes could technically handle with foreseeable battery technology, fully electric planes would need so much additional battery capacity that they could not practically be achievable.

Hybrid systems that allow for the use of aviation fuel, resolves the fuel requirement issue, even if the plane would be expected to be using the batteries most of the time.

Also, having decided on use of hybridization, the reduced dependency on advances in battery technology could allow the product to reach the market sooner.

I see a very large difference between hybridization in aviation and hybridization in ground transportation.

Except perhaps for the engine manufacturers, I think the aviation industry would be very happy to see electrification of aviation. There are potential cost and operational benefit that would only help the industry grow.

Yeah, we probably won't see hybrid aircraft in wide-spread use until solid state batteries eliminate the fire risk. No organic electrolytes, no fire. Also, no freeze at -60 C high-altitude cruise.

Prototype Electric Plane Built by Siemens and Magnus Aircraft Crashes in Hungary, Killing Both People on Board

CH3ERS!

 

[KarenRei]

No organic electrolytes, no fire

The cathodes and anodes can still be flammable. Particularly, if they utilize metallic lithium, it is very flammable indeed.

 

[lascavarian]

While I'm not nearly to this point yet, I'm thinking an arcjet could be maintained in an isotropic glow discharge mode with SiC mosfet arrays adjusting the current flow to various portions of the electrodes.

Great photo. Never seen anything like it. Interesting shapes.

Once worked with something sort of related to this type of discharge (I think) and we found that we had to consider hot spots that would develop. We sorted out problem issues but it could possibly be designed out with care. We were developing a source of UV at a certain frequency to activate a drug that was photosensitive. We were running on the edge to get the most UV possible given the space requirements etc etc. Seems this would be tuned to the IR spectrum in this application if I get it. Back to gravy thinking<grin>.

 

[KarenRei]

Once worked with something sort of related to this type of discharge (I think) and we found that we had to consider hot spots that would develop.

Bingo. Unconstrained, discharges tend to concentrate into tight, extremely hot arcs that heavily erode their electrodes. Hence my notion of using a MOSFET array between the power source and the planar electrodes on each side of the arc. Each individual MOSFET in the array would cycle at an increasingly high open:closed ratio as current flow increases through its pathway - thus encouraging more current to go through other pathways, and extinguishing any potential for hot arcs to form at that given location. I'd expect that to be able to maintain glow discharge conditions even at extreme currents. Well, as much of a "glow" as you can call megawatts of power flowing across a gap

I'm also hoping to be able to get some zero-velocity startup thrust with some valveless-pulsejet-style magic (I figured I'd let the genetic algorithm have a go at it; I've given it some options to play around with pulsation patterns and all sorts of complex internal geometry), in order to avoid the need for props or compressors to get up to ram speeds. Haven't yet added a reward function for low speed thrust - I'm still having it focus on high-subsonic thrust at the moment - but I'll put that in eventually, and see if it comes up with anything interesting.

Two issues I'm not even touching yet are noise and ozone. If I get far enough to actually be considering 3d printing a mini-engine to try out, then I'll put emphasis on aspects like that In case you're curious, I'm focusing on linear engines rather than radial. I'd love to be able to have the engines be the wings themselves. With vertical wingtips also functioning as engines, and one linear vertical engine in the nose, now you have three vertical points for lift, pitch and roll... use differential left-right thrust and you can yaw... and putting that all together, no control surfaces required. The practicality all depends on the thrust density and efficiency, of course. And whether it can pull off low-speed thrust with a compressor or prop.

(Wish I had a sizeable compute cluster... right now I only have a single 4 processor / 32 core machine doing my CFD sims for me :Þ )

 

[Artful Dodger]

Yep. I expect them to be very pricey. Their main market will probably be aerospace (both aircraft and spacecraft), where mass density is critical.

Wonder what their cycle life is like... Also, if they're using metallic lithium, I really want to see how they fare in safety testing.

Hi,

I'm not going to get too excited just yet. The company is a spinoff from a research university in China. Their founder and CEO (Cewen or 'Ce-wen' Nan) is lead author of this paper, just published on Nov 19, 2018:

https://pubs.acs.org/doi/10.1021/acsami.8b15121

The paper in question describes tests of a solid electrolyte compound used with a conventional anode (not metallic lithium) and a nitrogen-doped porous carbon cathode. That's why the test cell only acheives 400 Wh/Kg specific energy density (6.7% of theoretical LiS redox energy).

In tests, the cell retained 75% of its initial energy capacity after just 50 cycles. Worse, its so-called "high" ionic conductivity of 3.15×10-3 S cm-1 at room temperature is an order of magnitude less than current liquid electrolytes. That probably explains why they conducted their discharge tests at a very low 0.1C discharge rate (10x slower).

Overall, this is a bty chemisty yawn-fest, but I'm sure they'll attract a few glassy-eyed Venture Capitalists. Serves 'em right too (stay in school, kids: an advice).

I'm waiting to be impressed.

CH3ERS!

 

[JRP3]

Different? That is the same as the 2nd and 3rd zoomed in shots I put up.

By zooming in you created a misleading picture.

The * is before the prices, not hidden at the bottom, the bottom has before and after savings right next to the 'Next' button you must press to continue.

Are the actual prices the first thing listed? No. Why not? Because they are trying to distract the buyer. Gas savings depend on gas prices, electricity prices, and miles driven. The tax incentive depends on income and will probably change soon. Incentives in certain areas could actually lead to even greater savings, so list the real price first then talk about potential savings, you know, the way I talk about price when discussing Tesla vehicles to people.

 

[Artful Dodger]

The cathodes and anodes can still be flammable. Particularly, if they utilize metallic lithium, it is very flammable indeed.

You can burn lots of sugar. But why would you use it in a solid electrolyte.

 

[KarenRei]

You can burn lots of sugar. But why would you use it in a solid electrolyte.

Hot, molten lithium will reduce almost anything Lithiothermic reduction. Also burns hot in air.

 

[Artful Dodger]

Hot, molten lithium will reduce almost anything Lithiothermic reduction. Also burns hot in air.

Again, not an electrolyte. k, ttyl. Cheers!

 

[KarenRei]

Again, not an electrolyte. k, ttyl. Cheers!

Okay, I think there's a miscommunication here. I wrote:

"The cathodes and anodes can still be flammable. Particularly, if they utilize metallic lithium, it is very flammable indeed."

The ultimate be-all end-all of li-ion battery energy density, and one thing that solid state batteries have been cited as a key enabling tech for, is to use a lithium metal anode along with a high-lithium-density cathode, so most of the mass of your cell is active lithium.

 

[JRP3]

Indeed, from Art's link

The battery that Pogue whittled down still worked because it has a high energy density, thanks to the incorporation of a lithium metal anode.

 

[KarenRei]

Indeed, from Art's link

And hence my point of bringing up metallic lithium's fire risk. I'm not sure what we're in disagreement about here