petit_bateau
Active Member
3 knots sounds achievable for short distances with suitable tyres (terrible fuel consumption though both in water and on land).
Hubs sounds like a complete red herring.
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Investor Engineering Discussions
- Thread starter MC3OZ
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Hubs sounds like a complete red herring.
JRP3
Hyperactive Member
Pro's and con's of hub vs tail prop propulsion and steerage.
Nearly all favors tail. Would be fun to design a prototype as it could plug into the outlet in the bed.
Nearly all favors tail. Would be fun to design a prototype as it could plug into the outlet in the bed.
JRP3
Hyperactive Member
Maybe small jet drive. Because of vehicle shape displacement speed will be low no matter how it's propelled.
It sort of has to anyway. States use salt on their roads, people live on the coast, engine bays on ICE are already built to be (reasonable level of) pressure washer proof. The key additional items needed are vent line heights and cabin sealing (esp door drains).
Basically, it's an extension of good life extending engineering design.
JRP3
Hyperactive Member
While engine components are water resistant the engine bay itself is usually wide open below and not airtight at all. Plus the need to suck in air for the engine. Much easier to seal an EV completely. I do wonder how they'll handle the heat exchanger fans when they hit water, maybe just just them off completely when they sense resistance since the water will provide more than enough cooling. Or use vents to seal that compartment off from water but that would limit run time. Maybe that's what Elon means by short distances.
Should even be better than that, Megacharger is four V3 cabinets hooked to one plug.Haha, yeah, 650KWh/500mi = 1.3 KWh/mi. I wonder if there's less 'pepsi' and more 'frito lay' in those wagons...That's gotta be at 60 mph. Or maybe routes from the Modesto hub are more urban (less interstate?).
No matter! Build the damn thing, and ship it already. The time has come!
Cheers!
P.S. This 650 KWh pack size also reveals that MegaCharger is capable of at least 900 KW sustained charging rate. 650*0.7*2
Tesla Megacharger installation at Giga Nevada wraps up construction
Artful Dodger
"Neko no me"
Yeah, that's a sensible spec for long-term reliable charging. V3 currently provides 250KW, times 4 would be a megawatt peak. But the 900KW is the sustained charge rate over the first 70% of the packs's SOC. So 1MW peak at low SOC is fine, and hopefully not tapering too quickly.
Cheers!
Sure, but that calc is a pack limit
V3 cabinets can do 350kW (minus efficiency losses) from grid AC, more if they are cross connected to each other or Megapack
Pictures of V3 Supercharger cabinets
Each V3 cabinet can provide ~360kW. So with 4 cabinets they should be able to charge at up to ~1.4MW.
Captkerosene
Member
I used to fly Grumman Mallards in the VI. We could never keep the salt water out of anything. Electronics were the worst but the whole plane was subject to corrosion.
This is a warranty nightmare in the making. Elon needs to back off his boat claim right away or at least say that water infiltration is not covered in the warranty.
It will be super exciting to watch that charge cycle ramp up.
Back in the day, when Model S was made prior to superchargers or any compatible DC fast charger so the first time a Model S was plugged into a Supercharger the contactors would need to retract to initiate charging. Well, for some of us that was quite a harrowing experience. The sound of those contactors moving was so loud (as I assume were a bit sticky) that it caused me to jump out of my seat. It sounded like a loud and deep 'pop', but thankfully, as I stood outside the car (possibly a safe distance away) it started the ramp up. The following year, as I was working on AP camera calibration at the end of the line production line and heard the same sound, but very faint and noticed that right after calibration they were plugging in cars before going to the test track. This was the first time these had been supercharged and were making the same sound but obviously it was much less. By 2015, I couldn't hear that sound anymore. Yet another reason why Tesla is leading electric vehicles.
Not so much being sticky, the link bar is heavy and the magnetic field (also fighting the return spring) gets stronger the closer the switch is to being closed. So the bar is accelerating all the way until contact. Tesla treats theirs kindly (precharge), but they are rated for high voltage/ current so it wants to move fast when opening/ closing.
Should be better than that if you are talking pure altitude effects. Downhill has near 100% energy conversion efficency (if slope less than that needed for maintaing speed). Uphill is motor efficiency shift * driving load and operating efficency * potential energy gained.
Unless you have a lot of trucks and accelerate the air to truck speed.
(With losses due to walls being stationary)
Buckminster
Well-Known Member
I have a few GMG shares. Thought some of you would be interested in a recent breakthrough:
Graphene Manufacturing Group announces battery, cell and graphene production improvements in latest update
Graphene Manufacturing Group announces battery, cell and graphene production improvements in latest update
Gigapress
Trying to be less wrong
My understanding is that yes, for one freight container moving through a tunnel, the air drag is much worse than running it at the same speed on the highway, but if you have a series of freight containers in a train (whether directly linked together with mechanical connections or more likely software-linked) then the containers behind the lead container can ride through the slipstream with much less drag, such that the overall average drag per ton of freight for the platoon is less than if the same containers were shipped at the same speed on with a platoon of semi trucks on an aboveground highway.
In an aboveground highway with random traffic moving at different speeds, random wind, and open space, you end up with all kinds of vortices and turbulence that hurt efficiency.
I believe that in a tube the air would generally constrained to keeping its momentum directed downstream. Each container would basically be acting as a leaky piston, leaving a low pressure zone behind it for the next container. If hypothetically there were just one tube with a single entrance and exit and a container platoon went in, you would be able to feel wind sucking into the tunnel while standing at the entrance, even when the platoon has moved pretty far down the tunnel.
One confounding factor is that there will be fluid friction against the walls of the tube. They can make the walls super smooth but it's still going to be nonzero.
Aerodynamics is weird and sometimes counterintuitive things happen and I'm not an expert in this area, so maybe this is wrong. The only way to get a better idea would be to at least do computational fluid dynamics simulations or to build an actual prototype system and test it.
Gigapress
Trying to be less wrong
After skimming a few research papers just now on the subject of the aerodynamics of trains in tunnels, I am less sure of this. Apparently trains generally have more drag in tunnels and some other aerodynamic coupling challenges. The whole subject is more complicated than I had realized.
However, a lot of the problems are caused by the fact that trains generally enter and exit the tunnel at full speed, while freight containers in a Boring tunnel would enter and exit slowly.
However, a lot of the problems are caused by the fact that trains generally enter and exit the tunnel at full speed, while freight containers in a Boring tunnel would enter and exit slowly.
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