1. it makes changing a tire more complicated, and time is money, the longer it takes to change a blown tire the higher the penalties
2. when a semi tire goes, it goes hard, as GP noted with this arrangement the cowling will probably shatter, requiring a replacement (not just a replacement tire) and the pieces taking out other tire. If the cowling does not break, it will funnel bits of tire straight into the next tires, blowing all of them.
These covers could be useful, if they were made for containment. Requires something like kevlar that can stretch and absorb the impact.
... it's usually because the company was too cheap to buy anything but retreads.
DOT HS 811 060 is the study you should Google.
Sorry, not buying it.
Also, your comment is ironically pretty dismissive.
As an expert, do you think that the sporadic time/money cost of changing a tire could offset a significant reduction in fuel cost or trip time? How expensive would a tire change have to be to outweigh, say, a (conservative) 30% reduction in fuel cost?
Electric motors are brutally simple. So first that means they break down less often, second it means they're less complicated for the mechanic to figure out what the problem is.
And that's before the straight to technical advantages. Take braking. In a normal truck you turn speed into heat by rubbing brake pads. This gradually destroys the pads, so they're a consumable. But an electric truck turns much of the speed back into electricity instead. The pads get much less wear, you replace them less often.
If you take someone with you, you don't want to sit him/her to sit behind you. You want them to sit next to you. If you are on the road in the city, you have often colleagues with you, like in a moving company and alike. Such trucks are used in construction work where things damage easily because someone else crashes in your truck. No assistant in your truck will prevent that.
Honestly, it seems they may have talked to some friends or their delivery companies, but not with companies from the industry.
Just take a look, the very same long haul truck is also used by the construction workers. Only the the cabin is a little bit shorter.
Definitely feels like an intentional step towards "don't worry, Tesla will be driving these for you soon anyway".
The maintenance reduction basically only related to the motor itself. And, supposedly the "nuclear blast proof" windshield. A collision with a deer probably be much, much more expensive compared to a truck with a safari grill or plow mounted for safety.
According to the article, most commonly these are not used for regenerative braking, the energy is wasted as heat instead.
Eddy current brakes can be used for regenerative braking if there's an electric drive train (and high power electronics to handle it) but more typically the energy is just wasted as heat in a cooled resistor grid.
Mechanical/hydraulic braking can be used to spool up a flywheel and this was used in Formula 1 in late 2000's (now they use electrical regenerative braking instead).
Which of these techniques is commonly used in trucks?
https://en.wikipedia.org/wiki/Retarder_(mechanical_engineeri...
Originally, it is right that retarders were introduced to just having a non-destructive brake by just wasting the energy. That was around the 1980s. This was just to save maintenance cost as brakes were a big part of that costs.
The trucking industry is about costs and every little penny you can safe. So, years ago it started: Why do we waste that energy and do not re-charge the battery with that, because that reduces load from the generator and that will reduces fuel consumption?
Retarders have a huge impact in costs when your are counting miles. Retarders are having the disadvantage you can't brake to full stop with them. That's why they never worked in cars, because they are always additional to conventional brakes. So they add complexity and weight, both of which you want to reduce in cars.
Is the energy from braking really so small that it can't even fully charge the starter battery?
Honest questions. I figured that since regenerative braking in cars seems to double fuel efficiency, that order of half the power used to accelerate was recovered and I would have thought that was a very large amount of power to store.
Or is it because of the nature of long-haul trips? I know hybrids have much less advantage on the highway, maybe for long-haul trips the ratio of energy lost as air friction to energy lost in braking is vastly different.
It is always the question of what type of truck you are running. Do you just have storage goods, or do you have goods that need refrigeration? In the later you need energy to power that. As your truck does not know in advance what kind of trailer will be towed (connected, what is the right word?) the truck needs to be prepared.
Yes, extra power is dumped. But that is true for any kind of vehicle.
> Or is it because of the nature of long-haul trips? I know hybrids have much less advantage on the highway, maybe for long-haul trips the ratio of energy lost as air friction to energy lost in braking is vastly different.
Actually, Hybrid is very good concept for long-haul. Because on highways you can do coasting (sailing as we say in German) very efficient when you are in cruise control. Because with all the little hills up and down at the same speed, hybrid takes its full advantage.
I believe the normal way to handle this scenario is to just fall back to mechanical braking.
Potential energy lost by a truck going 10 m (vertically) downhill: 40 000 kg * g * 10 m = 4e6 J.
Capacity of car starter battery: 40 Ah * 12V = 400 Wh = 1e6 J. Let's guess a truck battery has 4 times the capacity of a car battery, so 4e6 J to full charge.
That's just down one small hill and all subsequent braking energy for the entire trip is wasted.
https://arstechnica.com/cars/2017/09/this-cement-quarry-dump...
(I don't think you would call a vehicle with mechanical KERS system a "hybrid", although it technically is as there are multiple propulsion systems in the vehicle.)
(Just being pedantic)
Design and maintenance procedure remains the same, maintenance interval drastically increased.
We won't know until it ships, but the front looks plasticky/crumble-zone-ey, and I'm not sure if Tesla would settle for a simple ladder frame.
Pressing a mechanical button or two should easily disassemble the glass gracefully. At the same while the glass is fixed it should ideally be immune to damage.
That seems like a meaningless claim without size and distance from the blast.
The only point is that it's stronger than normal glass, which is backed up with the video comparing the two different types of glass in a more realistic scenario.
5m to the explosion?
10km to the explosion?
What warhead? 10kt, 10Mt?
Supernova would be underestimating the power of your fist. Truly think about the history of the energy of your system!
It might be able to withstand an atomic glass but it's still going to crack if a big enough stone his it at 70mph.
I'm not saying that Tesla windshields are vulnerable from that, in fact, most windshields aren't. However it shows that resisting a blow from a hammer that is neither sharp nor hard is not a conclusive test.
The difference is in how they break. Laminated glass will generally crack, but otherwise stick together, while tempered glass will shatter, but into less-sharp pieces (to minimize the hazard of broken glass).
I don't know how much of this matters, but it stands to reason that what works on a side window might not be the same as what works on a windshield.
… but actually breaks easier than the iPhone 8 glass.
https://www.youtube.com/watch?v=8vHCBwJVeO4
I've dropped my case-less iPhone X 5 feet onto bathroom tile and not even a noticeable scratch afterwards.
(German Consumer report: iPhone X is most brittle of all iPhones)
I have no idea how automotive glass differs, but I imagine the difference in weight and thickness requirements does impact things a lot.
This reminds me of the unfolding problem of sun roof explosions.
Metals arent particularly strong. Glass, plastics, etc are all stronger (yield strength). But boy are they ductile, and very tough. Iron can take, literally, an infinite number of loading cycle.
You can make ceramics, glass, etc better but the overall performance package of iron is very hard to beat.
If I were to dismiss SpaceX as 1950s technology with modern electronics and engine technology the soviets mastered in the 60s would you be annoyed?
So why dismiss the truck manufacturing industry? Semis are very thought out solutions for their domain.
the semi: 1. costs much more than an iphone, which we're to assume accounts for the expensive windshield. 2. the windshield can be as thick as your attitude.
The full stream is only on YouTube in pirate form so far, so I don't expect links to last. The Tesla channel itself doesn't feature it yet.
https://tctechcrunch2011.files.wordpress.com/2017/11/tesla-s... ? I'm not sure what you mean. Looks about the same as the linked page to me.
> nor does it have near zero clearance between the cab and trailer which would prevent articulation, and nor does it have near zero ground clearance.
https://i.imgur.com/cECtzId.png https://i.imgur.com/EPIchQz.png
Ground clearance seems smaller because of how huge it is.
In the reveal the first truck does have the covers over the wheels, the second one doesn't. Check the livestream at about 3:00 [0]
[0]: http://www.renault-trucks.co.uk/media/image/nouvelles-gammes...
[1]: http://www.autoguide.com/auto-news/wp-content/uploads/2011/0...
https://www.reddit.com/r/cars/comments/16vmzp/why_are_americ...
Do you think you've just pointed out something that never occurred to him? Do you think if you could share your comments with him, he would stop and stare at you blankly and say "Shit. You're right."
You haven't just deflated the plan behind this entire, multi-year undertaking with your 5-minute analysis, as if you know more than all the engineers working at Tesla. The tone you're taking is just ridiculous.
I generally like what Musk is doing and think that Tesla is doing pretty great work, but he's not perfect and the pain points people are discussing in these threads are in no way unfounded. It's better to listen to the feedback and concerns in order to improve, rather than just fellating God-Engineer Musk and proclaiming his infallibility.
Is that why model 3 production is going so well?
Let's try this perspective instead:
"Decade-old electric car company moves up plan for mass production of new affordable long-range sedan by 2 years"
And then ask ourselves, after moving it up by 2 years, does a 3-month delay mean "things are going badly"?
If I say I'm going to leap 500 feet, and then I leap 450 feet, do you say I failed?
Yes, that's what the word failed means.
I think that's the point the OP above is trying to get at.
The consequence of not living up to an expectation depends on what's riding on that expectation. For a company trying to live up to a valuation higher than companies producing orders of magnitude more vehicles, I think it matters.
does it matter though?
https://seekingalpha.com/article/4122890-tesla-approaches-te...
I think OP is talking about the big picture, there will always be issues like the on with the production.
Amongst Model 3 fiasco Solarcity too currently has issues.
Tesla makes cars. We've known how to make cars for a while now - even electric cars. What was critical for Tesla was the vision: to see that we were approaching a tipping point where battery technology and cost would make a fully- (and only-) electric car feasible, and the strength of mind and purpose to ignore and/or out-think peoples' legacy objections and misgivings - e.g. with the Supercharger network. There are some Musk-ian details that are advances, such as the single integrated computer system, but that's a relatively small part of the whole.
In contrast, yes, SpaceX (just!) makes rockets, and yes, we've known how to make rockets for a long time. But they have done some things that the rest of the rocket industry haven't even got close to. Firstly, they've revolutionised the process and cost of producing a rocket in this class, by insourcing so much of it, and rethinking the necessary components and technology. Secondly, they've taken the concept of re-use and made it orders of magnitude cheaper (versus, what, the Shuttle?) than before, to the extent that it has/will completely turn the industry on its head. And the techniques and technology they've pioneered to facilitate this --not least the ability to land a 70m rocket upright on a robot barge floating out at sea-- are genuinely, truly revolutionary.
Lots of stuff has been test or tried before, but bringing things from idea to production ready with the efficiency required and cheap production is fantastically impressive.
You can claim 'it is not basic research' or whatever, but the reality is that they are pushing the envelop on so many topics at the same time that they are leafing all competition in the dust.
The project got taken over by NASA and the budget cut before being axed. You really do sound a bit too fanatical and should probably question more instead of accepting companies as entirely revolutionary.
Yep, SpaceX has barely innovated at all. Their contributions to space flight are not really of note.
The idea has been arouns for a long time and there have ben dozens of attempts of course, just as flying cars, autonomous cars, real A.I, space elevators.
Concept an execution are vastly different animals, it is at least 1000 times more difficult to achieve resuable rockets than to have the idea and at least 100 times more difficult than to try it.
http://www.truckingoffice.com/2012/interesting-trucking-indu...
I'd bet those fairings are needed to get the low cD, and that without them the economics are nearly as competitive. I'd give them the benefit of the doubt on having designed for blow outs as that seems rather basic.
http://www.roadandtrack.com/new-cars/future-cars/a12771645/t...
Having some tough glass though as they promoted would be really nice on an RV, I'm jealous.
Seeing as you still need to do a pre-trip inspection, I assume they swing out of the way pretty easily.
* What happens when a wheel seal goes? Do I have to remove all that ridiculous plastic on #2,3 axels??
* What happens when a tire blows? Is it going to destroy all that plastic and take out a few more tires in the process?
* Why all the glass? I've spend entire days replacing windshields for a 12 or so truck shop which generally come in two (drivers and passengers), the Tesla semi would require a crane and expensive replacements.
* Why is there no bumper or frame attachment points? Bumpers save the truck from damage, no one wants to buy $xxxxx front end, lights, etc when a deer in the bushes jumps into the middle of the road.
Honestly from my point of view it seems Tesla tried to apply personal EV to a semi. Did they do any research from tractor shops or mechanics? There is a HUGE reason tractor/trailers are easy to service.