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It's all a matter of tradeoffs. More unsprung weight has a negative impact on handling and ride, but in certain situations the packaging and/or performance advantages still make some sense. A rock crawling buggy for example would be awesome with wheel motors. No more suspension or steering angle limitations based on universal or CV joints, no more broken half-shafts, the ability to "tank steer", etc. Ride and handling are pretty much irrelevant for a vehicle designed to bounce off rocks mostly under 30 MPH. More in the real world, a cargo vehicle intended for urban use could have a lower, flatter load floor without the need to fit drivetrain components under it. Ride and handling are less important than capacity and efficiency in this application. All-wheel drive could be offered just by adding some wiring. Imagine something in the same class as a Ford Transit Connect, but designed around in-wheel motors attached to a battery "skateboard".
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Jan 27, 2018 15:56
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wolrah posted:More unsprung weight has a negative impact on handling and ride, but in certain situations the packaging and/or performance advantages still make some sense. But the way that paper describes it, we may have put too much emphasis on unsprung weight, it might be worth pursuing it in quite a few everyday applications. Cargo vans as you say, is probably a good bet, but small city cars will probably work too. There are many ways the car's traditional layout can be challenged with an electric drive train. My pet peeve, which I've mentioned before, is front overhang. You have the chance to get rid of so much of it, yet the Nissan Leaf for instance just gives zero fucks and adds almost a full wheel diameter of overhang ahead of the front wheel.  Maybe it helps with aerodynamics, but there's more practical ways of skinning that particular cat. I've seen many Leafs with dents and deep scratches along the front sides, presumably because the overhang is hard to keep track of in tight spaces. Ideally, the front should just be for containing some massive crash absorbing structures, between which there should be plenty of room for steering gear and plumbing. If there's any room left over, make it suitable for storing charging cables, tire repair and wiper fluid bags, but not so big that it compromises anything else, becomes a resonance box for cabin noise, etc. An opening hood might be a leftover from fossils, but you still need a maintenance hatch so it might as well be there.
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Jan 27, 2018 16:36
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wolrah posted:It's all a matter of tradeoffs. More unsprung weight has a negative impact on handling and ride, but in certain situations the packaging and/or performance advantages still make some sense. This is kinda what I meant with my reply. There are ABSOLUTELY applications where a gear-reduced traction motor at each corner makes sense, but its probably not passenger cars. It's just not the right place for it. I can't wait until modular, standalone battery packs become available. (Or some company makes it a bit easier to use an OE pack from Tesla or GM.)
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Jan 27, 2018 17:04
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LEDs still generate waste heat on the substrate or diode board, several brands have adopted quite beefy heatsinks as a result. The problem is, unlike HIDs and metal halides, LED waste heat is extremely localized and doesn't radiate as much as the aforementioned lamp types.
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Jan 27, 2018 20:09
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Brought home my model 3 today! No real issues - there was a chip in transit and they already scheduled for a fix. I immediately put it into sport mode and it feels amazing. It feels more light and sporty than the model S and it takes corners like a dream. The delivery experience was slightly more rushed than the S - they brought in 3 owners and explained the features and how to use the keys and such. Obviously it makes sense due to this car being half the price. The condition of the car was significantly better than our S pick up. Our S had a cracked sunroof, numerous scratches, rattles, the frunk latch was broken... -- however on the 3, we had one minor scratch which is already scheduled for repair. No biggy. It seems like tesla is getting their poo poo together, delivery quality wise. A note: A tesla can only be tied to one tesla account (at a time). So you either have to share a tesla account between multiple people or completely split it off. Other people may have known this but we couldn't find any information on this and both my husband and I wanted to have the 3 on each of our separate accounts. Instead we are only using my husbands account. Not a deal breaker - just something I wish we had known On the screen: Honestly, once I got everything set up, I barely looked at it, except to glance at speed. I haven't put enough miles on it yet for autopilot to be calibrated so i'll let yall know if adjusting speed on autopilot sucks. :3 officially a two Tesla household.
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Jan 27, 2018 22:47
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Ola posted:Ideally, the front should just be for containing some massive crash absorbing structures, between which there should be plenty of room for steering gear and plumbing. If there's any room left over, make it suitable for storing charging cables, tire repair and wiper fluid bags, but not so big that it compromises anything else, becomes a resonance box for cabin noise, etc. An opening hood might be a leftover from fossils, but you still need a maintenance hatch so it might as well be there. The Leaf is FWD and the hood in inexplicably jammed full of poo poo, I guess based on whatever ICE platform the based it on:  Thank god they left room for the driveshaft, exhaust and transmission! 
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Jan 27, 2018 22:53
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Inexplicable electric motor drivetrain Emergency battery disconnect 
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Jan 28, 2018 00:28
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The Leaf is like half the size of a Model S and 2/3 the weight. Obviously it's going to be packed full of hardware. Electric motors aren't magic.
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Jan 28, 2018 00:31
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angryrobots posted:Inexplicable electric motor drivetrain Great illustration. It's fine that it needs a bunch of hardware, the charger obviously takes some space as well. But the nose is mostly empty space. That radiator could have been packaged better. Other than that, and a ridiculous 12% speedo error on the one I've driven the longest, I quite like Nissan Leaves. e: e-Up knows what's up 
Ola fucked around with this message at 00:46 on Jan 28, 2018 |
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Jan 28, 2018 00:38
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Part of the function of that "empty space" is to provide a crumple zone so that in a front-end collision the motor controller doesn't end up in your lap.
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Jan 28, 2018 00:49
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Sagebrush posted:Part of the function of that "empty space" is to provide a crumple zone so that in a front-end collision the motor controller doesn't end up in your lap. No, it's not part of the crash absorbing structure, that doesn't begin until the panel gap you see intersecting the wheel arch. It's mostly empty space for the crash barrier to snack on while it's waiting for the impact. https://www.youtube.com/watch?v=3ZA-K8j4kX0
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Jan 28, 2018 01:02
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Who cares about overhang the car is going to ride like poo it weights 5000 pounds.
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Jan 28, 2018 01:47
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angryrobots posted:Inexplicable electric motor drivetrain 
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Jan 28, 2018 01:57
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What is this, the i3?
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Jan 28, 2018 02:31
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Sagebrush posted:Part of the function of that "empty space" is to provide a crumple zone so that in a front-end collision the motor controller doesn't end up in your lap. And aerodynamics
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Jan 28, 2018 02:48
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Three Olives posted:Thank god they left room for the driveshaft, exhaust and transmission! Often with a converted platform, the trans tunnel provides a very sizable percentage of chassis stiffness. Deleting it would require huge engineering changes, negating all the advantages of platform sharing.
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Jan 28, 2018 02:55
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The Leaf is not a shared platform, but the rear floor hump exists to hold some electronic components, and the emergency battery disconnect access door.
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Jan 28, 2018 03:49
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Ola posted:No, it's not part of the crash absorbing structure, that doesn't begin until the panel gap you see intersecting the wheel arch. It's mostly empty space for the crash barrier to snack on while it's waiting for the impact. There's still the 2.5mph bumper regulations though
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Jan 28, 2018 07:00
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hifi posted:There's still the 2.5mph bumper regulations though The overhang is probably designed with bumper regulations and aerodynamics in mind, but that doesn't mean overhang is the only way do those. The i3 has no silly overhang, but a lower drag coefficient (0.29 vs 0.32) and obviously also complies with safety regulations. The Leaf has a slightly better NCAP passenger rating, but the tip of the nose is rated "poor" https://www.euroncap.com/en/results/nissan/leaf/10939 https://www.euroncap.com/en/results/bmw/i3/8863 This message has been paid for by the mildly obsessed overhang awareness institute.
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Jan 28, 2018 10:49
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Cd on its own is actually misleading, you need to use CdA to actually compare cars in the real world. So calculate both frontal areas and get back to us.
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Jan 28, 2018 13:07
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drgitlin posted:Cd on its own is actually misleading, you need to use CdA to actually compare cars in the real world. So calculate both frontal areas and get back to us. You're wrong. It's not misleading to look at drag coefficient when you comparing designs, i.e how well each design has been optimized for its use. Only when you're comparing absolute drag values and energy efficiency. A brick has worse Cd than an SR-71 Blackbird, but due to it's tiny frontal area it has less overall drag. So would you say that an SR-71 is not as aerodyamic as a brick?
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Jan 28, 2018 13:31
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Cd on its own is not quite fair when used to compare cars from different size groups and layouts, because there are constraints like the size and shape of a human. Generally it is easier to reach a lower Cd with a larger car as there is more to play with in relation to the constraints. On the other hand, that room to play easily may result in larger area. So CdA may be more fair between different vehicle types, but both have uses. Also, the tip of the nose is not that important for Cd.
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Jan 28, 2018 13:41
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To bring this out of the realm of speculation, a quick google search tells me the Leaf has a frontal area of 2.28m^2 for a CdA of 0.729, and an i3 has a frontal area of 2.38m^2 for a CdA of 0.714.
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Jan 28, 2018 15:38
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How about cars with zero overhang look goofy and styling is still part of car design.
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Jan 28, 2018 17:53
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bull3964 posted:How about cars with zero overhang look goofy and styling is still part of car design. They look goofy because almost all other cars design has been constrained by the physical requirements of their mechanics. BMW managed to not only meet but excel at the safety requirements without putting a giant hood on the car, design shouldn't be dictated by physical limitations that no longer exist.
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Jan 29, 2018 00:40
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Three Olives posted:They look goofy because almost all other cars design has been constrained by the physical requirements of their mechanics. BMW managed to not only meet but excel at the safety requirements without putting a giant hood on the car, design shouldn't be dictated by physical limitations that no longer exist. They excelled at making the most awkward looking car in the world. As a reminder, this is a timeline that also contains the Nissan Cube.
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Jan 29, 2018 01:21
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Are Tesla fanboys pro- or anti- Scorpio comparisons?: https://www.instagram.com/p/BeeYW0NA1HU/
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Jan 29, 2018 02:57
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Ola posted:You're wrong. It's not misleading to look at drag coefficient when you comparing designs, i.e how well each design has been optimized for its use. Only when you're comparing absolute drag values and energy efficiency. A brick has worse Cd than an SR-71 Blackbird, but due to it's tiny frontal area it has less overall drag. So would you say that an SR-71 is not as aerodyamic as a brick? You’re comparing two different cars; use CdA.
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Jan 29, 2018 02:58
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MrYenko posted:They excelled at making the most awkward looking car in the world. And the catfish faced Nissan Leaf. Seriously, the Gen 1 Leafs are not pleasant looking (I know, it's not what you buy one for).
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Jan 29, 2018 03:28
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kimbo305 posted:Are Tesla fanboys pro- or anti- Scorpio comparisons?: I understand nothing of comics, I understand Elon less. At least we can look forward to some entertaining confusion on the finance blogs. drgitlin posted:You’re comparing two different cars; use CdA. See above. The Leaf is worse both CdA and Cd, but you're still misunderstanding. CdA is using the same unit of weight to compare apples and oranges. Say an orange has 16 grams of sugar, an apple has 12. Is the orange more sugary? You get less absolute sugar by eating the apple, but it might be more interesting to know how many grams of sugar each has per unit of total weight. If you expanded an i3 so it had the same interior volume as a Leaf, for actual fair comparison of the design's aerodynamic efficiency, it would have less drag because it has lower Cd. Because they now fill the same-ish space, they have same-ish frontal area so that factor doesn't matter. So you compare Cd. That's why it's an often published spec, otherwise the industry would just publish some standardized drag value in Newtons at x speed. I think I learned this in a car magazine once, informative stuff.
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Jan 29, 2018 03:56
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kimbo305 posted:Are Tesla fanboys pro- or anti- Scorpio comparisons?: Already ordered mine. The money goes to fund the boring company, so win/win.
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Jan 29, 2018 06:38
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Ola posted:If you expanded an i3 so it had the same interior volume as a Leaf, for actual fair comparison of the design's aerodynamic efficiency, it would have less drag because it has lower Cd. Because they now fill the same-ish space, they have same-ish frontal area so that factor doesn't matter. So you compare Cd. That's why it's an often published spec, otherwise the industry would just publish some standardized drag value in Newtons at x speed. I think I learned this in a car magazine once, informative stuff. I disagree with you and your source completely. "The design's aerodynamic efficiency" does not exist outside the context of the rest of the car. Car magazines publish whatever press package car manufacturers give them, they don't actually care to give customers good information. They care to keep their advertisement dollars. Any article in a car magazine defending the way car magazines do business is bullshit. Comparing the leaf and the i3 isn't apples to oranges. It's more like comparing Granny Smith to Pink Lady. They're both electric cars in a similar price segment designed to carry five passengers and a little bit of cargo. Their absolute drag values compared to one another are absolutely relevant.
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Jan 29, 2018 08:50
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pun pundit posted:They're both electric cars in a similar price segment designed to carry five passengers and a little bit of cargo. Their absolute drag values compared to one another are absolutely relevant. No they aren't, you misunderstand even more. We're not comparing them in general, we're not looking at overall efficiency, we're looking specifically at nose stupidity - even if the i3 is more efficient and has less absolute drag. If you compare absolute values, a brick is more aerodynamic than an SR-71. But we are discussing the merits of the design. With this qualitative element in mind, I would say that the SR-71 designers deserve more credit for their aerodynamic work than the brickmaker, even if sadly their airplane is less aerodynamic than said brick, in absolute terms. The issue at hand is whether or not the Leaf has a stupid nose. drgitlin says it is relevant for aerodynamics. If it was indeed, my opinion of its stupid rhesus monkey nose would improve. "Aha, it looks stupid, but you go further per kWh, that's not so stupid" I would say. In comparison, the i3 looks like a bulldog. Intuitively, it seems more draggy. But it turns out, the designers have worked very well and made it more aerodynamic, in relative terms, than the Leaf. So the Leaf doesn't need its stupid nose to move smoothly through the air - and that holds for a Leaf at any scale. If you could magically resize the two cars to any size, their absolute values would change, misleading you, but the drag coefficient would not. A 15 ft tall i3 will be very draggy, but its shape will be less draggy than a 15 ft tall Leaf. We know this by looking at Cd. Hence it is a "more aerodynamic design" - which is popular vernacular and not a scientific term. Absolute drag, only interesting for overall efficiency. Which the i3 is better at than the Leaf. You measure that much better by simply looking at energy consumption, which the i3 is better at than the Leaf.
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Jan 29, 2018 09:52
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Ola posted:No they aren't, you misunderstand even more. We're not comparing them in general, we're not looking at overall efficiency, we're looking specifically at nose stupidity - even if the i3 is more efficient and has less absolute drag. If you compare absolute values, a brick is more aerodynamic than an SR-71. But we are discussing the merits of the design. With this qualitative element in mind, I would say that the SR-71 designers deserve more credit for their aerodynamic work than the brickmaker, even if sadly their airplane is less aerodynamic than said brick, in absolute terms. If engineers could make a plane that was capable of the SR‐71’s mission with the frontal area of a brick, I would be drat impressed. So what if a brick isn’t a very imaginative shape? What matters is the whole package. Coefficient of drag and frontal area are both valid angles of attack. Ola posted:If you could magically resize the two cars to any size, their absolute values would change, misleading you, but the drag coefficient would not. A 15 ft tall i3 will be very draggy, but its shape will be less draggy than a 15 ft tall Leaf. We know this by looking at Cd. Hence it is a "more aerodynamic design" - which is popular vernacular and not a scientific term. It turns out that you can’t do that because car components, passengers, and cargo are not liquids that can re‐shape to fit arbitrary containers. Platystemon fucked around with this message at 10:19 on Jan 29, 2018 |
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Jan 29, 2018 10:14
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Platystemon posted:If engineers could make a plane that was capable of the SR‐71’s mission with the frontal area of a brick, I would be drat impressed. I apologize for stretching your imagination past its breaking point.
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Jan 29, 2018 10:29
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Aha, but do we know that the nose of the car is the specific piece that's causing the difference in drag? For instance, one of the draggiest parts of any car is the wheels -- they present a flat, square surface to the wind (where they are exposed below the car), they operate in a critical low-pressure zone under the car, and they generate turbulence. Perhaps the i3's dumb wagon wheels are the reason its cD is lower than the Leaf's, and the Leaf's nose is more aerodynamic than the i3's design?
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Jan 29, 2018 10:35
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Ola posted:I apologize for stretching your imagination past its breaking point. My imagination didn’t feel a thing.
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Jan 29, 2018 10:50
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Sagebrush posted:Aha, but do we know that the nose of the car is the specific piece that's causing the difference in drag? OMG some good points! Maybe it is, I don't know. If it is, I'd appreciate the dumb wagon wheels a lot more.
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Jan 29, 2018 10:52
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Platystemon posted:My imagination didn’t feel a thing. When your parents told you about the birds and the bees, did you go "actually dad, you can't have sex with a bee"?
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Jan 29, 2018 11:03
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No, you keep misunderstanding. CdA tells you the actual amount of drag the actual car has in the actual world. I don’t care about some thought experiment where you pretend they’re both the same size. And stop mentioning Blackbirds and bricks.
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Jan 29, 2018 12:53
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