[HN Gopher] Students break acceleration world record ___________________________________________________________________ Students break acceleration world record Author : giuliomagnifico Score : 210 points Date : 2022-10-12 18:34 UTC (4 hours ago) (HTM) web link (www.uni-stuttgart.de) (TXT) w3m dump (www.uni-stuttgart.de) | jcmontx wrote: | Now take the tech and apply it to the next gen of Formula E! | amelius wrote: | What are those solder joints at 0:50 in the video? | nsxwolf wrote: | I'd love a straightforward view of what that really looks like, | instead of a bunch of fancy camera work. | Ralo wrote: | I've been a huge fan of drag racing, and the engineering behind | it. I've seen the influx of electric cars making their way into | the scene but they never seem to be competitive, and that comes | down to their top end. | | The extreme end of combustion engines, you really got top fuel | dragsters. Not much faster land vehicles than those. The flaw | with those, they got about 2 uses tops before it needs to be | completely gutted and rebuilt, not great as a weekend track car. | As well, it's somewhere around $1000/second to drive it. | | You can sit more in the middle with people getting 1000hp daily | drivers. With dynamic tuning, flex fuel, etc you can get the best | of both worlds. As well, DCT AWD transmissions make grip/shifting | issues a thing of the past. | | However, these middle ground drag cars can still get eaten by a | $130k bone stock tesla*. The extra weight, infinite torque, and | zero shifting is a real advantage, even if their top end isn't as | strong as their ICE counterpart. | | I've always dreamed of building a hybrid car with tiny tiny | battery packs. Maybe enough charge for 4-5 passes. Enough for a | day at the track. But have a fully built high revving ICE. You | get the launch in full electric, your ICE can be fully spooled, | and ready to switch over automatically. Perhaps the smaller | batteries couldn't put out enough power? Who knows. | | *Plaid | PragmaticPulp wrote: | > You can sit more in the middle with people getting 1000hp | daily drivers. With dynamic tuning, flex fuel, etc you can get | the best of both worlds. As well, DCT AWD transmissions make | grip/shifting issues a thing of the past. | | > However, these middle ground drag cars can still get eaten by | a $100k bone stock tesla | | A 1000HP drag car with AWD and a DCT shouldn't "get eaten by" a | $100K Tesla (unless you actually meant the $130K Tesla Model S | Plaid). Not unless someone is lying about their power numbers | or doesn't know how to set up a car. | | The Tesla's drag mode is a neat party trick and perfect for | singular drag races, but spending 15 minutes preconditioning | your battery before you can launch is also kind of ridiculous | by ICE car standards. | Ralo wrote: | >unless you actually meant the $130K Tesla Model S Plaid | | Rounding error to $100k. Yes I'm referring to the Plaid. | People have taken those cars and gutted the interiors on | them, and demolished drag races. | | > spending 15 minutes preconditioning your battery before you | can launch is also kind of ridiculous by ICE car standards. | | It's far from rare to see people setting up an array of box | fans, and bags of ice around their engines to cool it off | between passes. Many high high powered cars won't even have | full size radiators. | slowhand09 wrote: | Nope, your typical Tesla isn't the rocket you describe. Most | are quick, but not that quick. I frequently get challenged by | wannabes while commuting. I rarely take the bait, but I've yet | to have one live up to the hype. | gffrd wrote: | What are you driving that has Tesla drivers wanting to tangle | with you so often?? | | Muscle or German? | | (Wondering whether the motivator is performance or ideology) | KindAndFriendly wrote: | slowhand09: "My daily driver is a Hellcat..." | Ralo wrote: | I should have specified, Tesla Plaid. Of course a Model X | isn't as quick as a fully built 1000hp AWD DCT GTR. Apples to | oranges. | masklinn wrote: | > Not much faster land vehicles than those. | | Top fuels top out around 350 mph. The land speed record is 760 | (manned, for unmanned it's a rocket sled exceeding mach 8). | | The land speed record has been above 350 since 1938: | https://en.wikipedia.org/wiki/Railton_Special | | There are in fact a fair number of much faster land vehicles. | Ralo wrote: | Yes, their top speed is much much faster. But put that same | vehicle on a 1/4 mile race track, racing a top fuel dragster. | The top fuel dragster produces around 5g's at launch, the top | speed cars are very very slow to build up speed. So much so, | they usually require a pilot vehicle just to start them, like | you trying to start pedaling your bicycle in 5th gear. You'll | want a push. It's a different type of racing. | | > Not much faster land vehicles than those. | | Its a poor choice of words, perhaps 'quick' is a better word? | gorkish wrote: | > But have a fully built high revving ICE | | Once you do this you are sunk due to weight. If you need | another torque band, far better to add a second electric motor | with a different gear ratio (Tesla already does this) or use | something like a DSG with the single motor. | jmpeax wrote: | What an incredibly frustrating video. Here is the actual run | without all the unnecessary fast-and-furious computer graphics | rubbish at the start: | https://www.youtube.com/watch?v=xjDK0LhKkMs&t=76s | mattfrommars wrote: | The title should add for electric vehicles. Aren't top fuel | dragsters quicker? | semi-extrinsic wrote: | Yes, IIRC they're doing somewhere around 0.7s? There's even | been road legal tuned-up versions of the Nissan GT-R doing | around the 1.5s mark. | [deleted] | topspin wrote: | Jalopnik claims 0-100 _MPH_ (161km /h) is 0.86 seconds. | ncmncm wrote: | I wonder if they are allowed to put a fan in to suck it down to | the road surface, offering better static friction to the tires. | You would of course start the fan before the wheels. | | That would mean you could get by with lighter-weight tires, an | important concern. | ihunter2839 wrote: | Yes, this car uses powered ground effects (PGE) to achieve the | necessary downforce at low speeds (they mention this in an | instagram post) | | In Formula SAE in the US, PGE systems are not allowed, but in | the European equivalent they are. | | Take a look at the Speirling at Goodwood Festival of Speed for | an awfully mean fan car. | https://www.youtube.com/watch?v=xtvT2XYlcOY | tshaddox wrote: | That's what this electric fan car does: | https://www.roadandtrack.com/news/a40424619/watch-an-electri... | mburee wrote: | Why wouldn't they incorporate design from top fuel dragsters? | They reach 100mph (!!) in under a second. | sethgrisham wrote: | It's a track car designed for road races, not drag racing. This | car is essentially meant to be a jack of all trades, whereas | top fuel dragsters are probably the most purpose built car of | all time. | eenell wrote: | Why would an EV incorporate tech from top _fuel_ dragsters? | What tech besides tyres and aero would they adopt? | antonvs wrote: | Flames, smoke, and the occasional explosion perhaps? | m463 wrote: | I'm pretty sure top fuel dragsters are all about tires and | aero and only inconsequentially the power source. | | It might be an easy problem to solve acceleration to 100km/hr | since you don't have to carry batteries to go an entire 1/4 | mile | [deleted] | ominous_prime wrote: | not many other vehicles have the ability to transfer | >6000ft/lbs of torque down to the pavement to be able to | accelerate at 5gs | orangepurple wrote: | The clutch which fuses itself into a solid unit instantly | sbierwagen wrote: | The video shows it using kart tyres, and I would be | interested to see what it would do with proper drag radials, | since they change shape quite a lot during a launch: https:// | www.caranddriver.com/features/columns/a26089565/drag... | | >The massive torque channeled through the rear axle shifts | the load of the car rearward and tries to twist the tire on | its 16-inch beadlock rim. The sidewalls wrinkle as the tire-- | generally running between 6.0 and 10.0 psi of pressure-- | shrinks in radius by more than six inches and the tread | effectively balls up at the front of the contact patch. That | compression of the tire expands the contact patch to almost | 250 square inches--larger than two side-by-side sheets of | 8.5-by-11-inch paper. The compression of the tire also means | that the final-drive ratio is effectively shortened for a | harder launch. By the time the tire has released the torque | stored in its wrinkled sidewalls and tread and grown back to | its original size, the Top Fueler is already pulling more | than 4.00 g's of acceleration. | | >After the car launches, inertia grows the tire to as much as | 38 inches in diameter, simultaneously lengthening and | narrowing the contact patch. This effectively lets the final- | drive ratio grow taller for higher speeds and reduces rolling | resistance as the vehicle hits terminal velocity. | | Effectively a big CVT with no moving parts. | Animats wrote: | Wheel spinning and burning rubber? | | Electrics going for maximum acceleration usually don't do | that, because once the wheel is spinning relative to the | pavement, friction is reduced and there's less acceleration. | Watch videos of Teslas in launch mode. | 1970-01-01 wrote: | FFS. The run is about 82 seconds into the video. In the amount of | garbage time leading up to it, they could have shown it 56 times. | https://youtu.be/xjDK0LhKkMs?t=82 | thomastjeffery wrote: | By putting 4 spaces in front of your link, HN has formatted it | as a code block instead of a clickable link. | raydiatian wrote: | For the amount of spaces he put in front of his link slowing | me down on my way to YouTube, I could have watched the car | accelerate to 100 two or three times. | ivanjermakov wrote: | More than that, the actual record part haven't delivered a good | sense of acceleration | lowestprimate wrote: | The acceleration record is probably the manhole cover launched | via nuclear explosion. Accelerated to 125,000 mph in a | millisecond. https://www.businessinsider.com/fastest-object- | robert-brownl... | NaturalPhallacy wrote: | 100 km/h is 62 mph | whycombinetor wrote: | Yes, zero-to-60 (in mph) or zero-to-100 (in km/h) is the | standard acceleration measure for cars across the world. | aidenn0 wrote: | Not for drag racers though, which are usually measured in | speed attained from a standstill over 1/4 mile. | squeaky-clean wrote: | Dragsters definitely measure their acceleration for | bragging rights, it's usually a 0-100mph metric though. And | of course bragging rights mean nothing if your car doesn't | win the actual race. Top-Fuel dragsters race only 1000ft | because they're so insanely fast it's dangerous to let them | go farther and build up even more speed. | unwind wrote: | I extend the award of most confusing expression to you, | for "0-100 mph metric". | | I _know_ that "a metric" is not the same as "the metric | (system)", but I really had to stop all neurons and think | a little. | | Also, are 1000 ft a quarter mile? I have _no idea_ , so I | had to Google and it's not, that'd be 1,320 ft. | squeaky-clean wrote: | Haha upon reading it, that is a bad phrasing. My American | is showing. Funny because I usually watch European racing | series which use km, but dragsters are fun to keep track | of and those are imperial. | | Also you can be sure 1000ft isn't a quarter mile because | that's far too evenly divisible. | elif wrote: | Do you mean duration and not speed? | | Sure the readout gives a max speed reached but the numbers | they compete over, and the numbers which establish car | classes, are the time duration for the 1/4mi run. | megraf wrote: | Call me old fashion, but I'd really gain more out of the | demonstration videos if they linked to the time the record (or | whatever content) started. | | Yes, it's a beautiful video. | LeifCarrotson wrote: | Students break acceleration world record...for _electric_ | vehicles. | | This isn't close to the record for dragsters; if they can | increase the energy density per unit mass there are traction and | downforce improvements that can be used to improve this. It's | very hard to beat chemical energy like detonating gasoline or | nitromethane - you're looking at roughly a factor of 100, with | ~40 MJ/kg for gasoline and 0.4 MJ/kg for a lithium ion battery - | especially if you're racing through a 15 PSI gas that you can use | in your chemical reaction without having to accelerate it | onboard. | | I suspect that traction control for an electric motor may someday | allow electric vehicles to exceed the records held by internal | (well, mostly internal) combustion engines. You could keep the | tire at exactly the right amount of slip for maximum | acceleration, rather than trying to balance centrifugal clutches | to get just the right amount of power at the right time. | | I wonder what the record is for a vehicle that can pick up | electric energy from a tether/rail/overhead wire...though cables | that can carry megawatts of energy are probably pretty heavy. | | Edit: I think the most interesting category here is the typical | friction-propelled, human-carrying vehicle of either chemical or | electric power sources. Railguns, rockets, fan cars (using active | downforce), and vehicles which engage the ground by rack and | pinion are qualitatively different. When the question is | accelerating your own mass forwards using the friction developed | by your own mass being pulled down by gravity, there's an | interesting optimization problem trading off weight and power. | MontyCarloHall wrote: | >cables that can carry megawatts of energy are probably pretty | heavy | | Required cable thickness (and thus weight) is proportional to | current, not voltage. Conductors to carry megawatts of | electricity could be fairly light as long as the voltage is | extremely high and the amperage relatively low. | jvanderbot wrote: | And magnetic force is a function of current, and magnetic | force is what drives wheels. Technically you are correct, but | thick cables are actually needed to do lots of translation | from electricity to movement. | willmadden wrote: | I don't think there's a problem with cable weight with | electric motors. Production EV's today have ridiculous | amounts of torque and don't require prohibitively heavy | cables. | | The issue with acceleration using wheels is gravity. You | are limited to 1g, the downforce on the wheels, which you | use for traction to push the vehicle forward. Spoilers | increase the downforce on the vehicle beyond 1g, but the | energy required to do that is proportional to the drag on | the spoiler. | | Short of a rocket engine, the way to accelerate beyond 1g | with a wheeled vehicle is to have a downforce fan. That can | be powered by combustion or by electricity. I don't know | which would offer the highest power to weight ratio. | [deleted] | lazide wrote: | I'm not sure having a 'reverse Helicopter' on the back of | your vehicle really qualifies as 'ground vehicle' at that | point. Especially if it's providing enough force to | literally drive upside down on a ceiling somewhere. | stefs wrote: | it's as ground as can be, short of a tunneling machine | maybe. | solidr53 wrote: | BEV used to have around 80kg of copper [1], nowadays, | manufacturers are moving towards 800V architecture | attempting to cut the weight in half. | | I also feel like 800V cars also maintain their maximum | power better on lower SoC than 400V systems. | | [1] https://www.copper.org/publications/pub_list/pdf/A619 | 2_Elect... | kroeckx wrote: | For the torque, you can use a low current using more | windings, which has the same effect of having a higher | current with less windings. | | The acceleration you can reach is mostly limited by the | peak current and the force constant, but the maximum speed | you can reach at that acceleration is mostly limited by the | voltage you have available because of the back-EMF. A | simplified formula is that the voltage you need is R * I + | v * BEMF. The higher the voltage is, the better the | insulation between the windings needs to be. You need to | find a balance between the different properties. | happyopossum wrote: | More windings = more weight - you're gonna pay for it | somewhere. | sudosysgen wrote: | Sure but the wiring is thinner, thereby somewhat | equalising. | [deleted] | MichaelZuo wrote: | It does seem like a clickbait title. | isoprophlex wrote: | > I wonder what the record is for a vehicle that can pick up | electric energy from a tether/rail/overhead wire... | | Getting dangerously close to "car launched by a railgun" | territory, hehehe | tshaddox wrote: | Yep, it very quickly becomes a question of what exactly | you're trying to test. If you take energy and power density | out of the equation by allowing unrestricted access to | external fixed energy delivery infrastructure, the only thing | left to test is traction management (assuming you're not | allowing things like adhesive tires, cog rails, active | downforce, etc.). If you _do_ start to allow those post- | traction things, you are as the stage where you might as well | build a railgun. | dheera wrote: | > though cables that can carry megawatts of energy | | Not really, high speed train lines do it all the time. They | usually operate at 25 kV or 50 kV and often consume a few | megawatts per train. | | (At 50 kV, one megawatt is only 20 amps, which you can deliver | on 12 AWG wire, theoretically.) | titzer wrote: | Uh no, do not put 50,000 volts through 12 AWG wire. | the_third_wave wrote: | When I went to high school the teacher told about a science | fair where someone had put a sign next to his project | reading: WARNING 2 million Ohms | | (or something like that, I don't remember the actual number | of Ohms for this specific project) | | A remarkable number of people kept their distance from this | obviously dangerous experiment. | | The chemistry-equivalent of this joke is to warn everyone | around you of the presence of dangerous _di-Hydrogen Oxide_ | which kills hundreds of thousands of people every year. | elliottkember wrote: | 2 million ohms? Not bad, not terrible. Vasily, get the | good Ohmmeter from the safe. | rascul wrote: | > The chemistry-equivalent of this joke is to warn | everyone around you of the presence of dangerous di- | Hydrogen Oxide which kills hundreds of thousands of | people every year. | | https://dhmo.org/facts.html | comboy wrote: | In their defense, maybe those people didn't know if it's | a project by a very clever student or by the one who | mixes up units ;) | quickthrowman wrote: | Why not? You obviously wouldn't do it to a THHN conductor | that is rated for 600v, but there are certainly #12 AWG | conductors rated for higher voltages. They have a whole lot | more insulation/layers than a regular 600v rated conductor, | see: https://www.powerandcables.com/wp- | content/uploads/2019/10/Fi... | | High voltage utility distribution lines aren't insulated by | anything other than porcelain bushings and air. | gooseyman wrote: | Came here to say this. Romex/THHN might be a bad idea, | but that's because they weren't insulated for this | purpose. 12 AWG would work. | jefftk wrote: | What goes wrong? | WJW wrote: | Most store-bought wires won't have sufficient covering to | prevent arcing, so you might get a short circuit | somewhere. If you insulate the wires sufficiently | however, any wire will take almost any voltage. It's the | current you should worry about, as other commenters have | already mentioned. | cesaref wrote: | As has been stated, voltage isn't a limitation, its the | current that. Go and look at the HT wiring used in a | cathode ray tube display, and you'll see it's a lot less | that 12 AWG, and happily carries 10-20kV. | josephcsible wrote: | The term "12 AWG" only specifies conductor thickness. | Voltage is limited by insulation and current is limited by | conductor thickness. Assuming sufficient insulation, it's | safe to run arbitrarily high voltages through any | conductor, since it doesn't even "see" the voltage. | [deleted] | spinningslate wrote: | yes, but: | | 1. You need a _lot_ of insulation at 50kV 2. I'm no expert | but I very much doubt you could run a motor at anything | approaching that voltage. Current electric cars, for example, | run c400V as the main motor supply. So there would need to be | voltage conversion, which adds weight and bulk. | tomek_ycomb wrote: | There already is conversion. The motors are inductors and | phase current can be much higher than battery current | quickthrowman wrote: | I know for certain there are 13.8 kV motors, I don't see | any reason why higher voltages aren't possible for motors. | bobthepanda wrote: | Usually you need to transform power anyways on a train, | because | | * lights, plug sockets, etc. are all at normal household | voltages | | * often trains will run on multiple voltages, so a | transformer needs to be involved anyways | | * lower voltages let you have thinner insulation, so | thinner wires let you save space for things that matter | more like a bigger passenger cabin | kwhitefoot wrote: | Quite a few of the newer EVs have 800 V batteries to make | fast charging more practical with cables light enough to be | handled by ordinary humans. | | You can make an electric motor run on pretty much any | combination of voltage and current. You just have to make | the appropriate trade-offs in insulation, conductor cross | section, etc. | | ABB (my former employer) makes motors that run on 13.8 kV | with a power of up to 29 MW. See | https://new.abb.com/motors-generators/high-voltage- | induction... | jackmott wrote: | whartung wrote: | As a visceral experience, there are few things that top a Top | Fuel drag race. They're really something worth experiencing at | least once personally. You really just have to be there. | naikrovek wrote: | yeah the real "all I hear is ringing" experience can't be | beaten. | | I've been to two Top Fuel drag races and I left feeling like | I was surrounded by people who have just enough | sophistication to know that they like to play with fire | whenever possible. | | they are not like that, of course, but they were definitely | caught up in the visceral feeling of watching a race and I | was caught up in the idea that I'd never be able to hear | again. | | I do not recommend races, myself. | alfalfasprout wrote: | Bad take. Wear ear protection. Problem solved. | karamanolev wrote: | Earmuffs? Isn't it worth seeing (maybe just once) even if | you do wear hearing protection? | naikrovek wrote: | I was wearing hearing protection. have you ever been to | one of these? or maybe a concert? hearing protection does | not block incoming sound, hearing protection attenuates | incoming sound. after hearing protection it's all still | very, very loud. loud enough to cause ringing immediately | and for days afterwards. | yamazakiwi wrote: | Worth seeing to whom? I'm not trying to be contrarian but | none of that seems enjoyable or a Top 3 visceral | experience when I'm not actually involved with the | action. | | It's weird to hear someone say something is in general a | Top Experience. | whartung wrote: | Even in todays world of crazy sound systems and 8K video, | some things are simply worth experiencing live. "You have | to be there." | | Like live music, like going to a playoff game, watching a | rocket launch. Even if you don't care about the race, the | game, or the music. The energy of being in these places, | experiencing it, feeling it, the spontaneous giggles, the | sense of awe being caught in the middle of it, has a | value all its own. You can watch the race on TV, catch | the game in a pub, listen to the live recording over, and | over, and over again. | | But it's not the same as being there. | yamazakiwi wrote: | Oh, I don't have interest in seeing a drag race in video | either which is what is leading me to believe it wouldn't | be that exciting. | | I agree with what you're saying about live events vs | video. | samatman wrote: | Some of us like very loud sounds punching us right in the | chest. | | Video is completely useless for this. Drag racing is not. | WalterBright wrote: | Wearing top quality ear protection is a requirement. They | work, and do not subtract from the enjoyment. | sixQuarks wrote: | I went for the first time couple of weeks ago. Standing right | by the starting line, when the top fuel funny cars take off, | they get engulfed in a bubble of blurriness, caused by the | burning nitro, coupled with the tremendous rumbling which | causes your eyes to shake, it's impossible to get a clear | view of the cars on takeoff. It's insane. | WalterBright wrote: | There are some things that audio recordings simply cannot | capture. Top Fuel is one of them. When I go, I wear ear muffs | that are made for target shooting. | | The pulses are so loud it is like being punched in the chest. | Sometimes the engines explode which is also fun as the | smoking parts fly around. | | Once, the Top Fuel driver had the silly thing in reverse. The | christmas tree turned green, and he launched backwards. He | had lightning reflexes, chopping the power incredibly fast. | The thing still flew back nearly 100 feet, and if it had | continued would have climbed up the grandstand behind it. | | I never, ever, ever stand in front or in back of a dragster | when its engine is running. I also do not stand radially to | the engine (when they blow, the parts fly out radially). | | Other than that, it is great fun to go to a race in person. | It's the only motor sport left where the attendees can go | into the pits and watch the mechanics at work. Watching a | team rebuild a V8 engine in minutes is amazing. Then they'll | fire it up to test it. Blipping the throttle produces shock | waves that you can see hitting the bystanders. | | The barely restrained violence of those machines is just | crazy mad fun you'll never get from watching it on TV. | rootusrootus wrote: | > It's the only motor sport left where the attendees can go | into the pits and watch the mechanics at work. | | Definitely not true. We walk the pits every time we go to | an IndyCar race. And of course we do the same at the lower | level SCCA-level stuff. Trying to think the last time we | couldn't get a pit pass and coming up blank. | WalterBright wrote: | I've bought a "pit pass" at several motor sport events, | and there remained a fence separating the public from the | pits. | VBprogrammer wrote: | > It's the only motor sport left where the attendees can go | into the pits and watch the mechanics at work. | | It's almost certainly not useful for you but one other | motorsport which is comparable in this way is the IOM TT. | You can walk around and speak to the guys on the pit crews | as they work. | | It also offers some visceral experiences, like standing 2ft | from the bikes passing you doing the best part of 200mph. | In fact when I went a couple of years ago selfie sticks | were banned, as you are so close to the action that there | is a real danger of hitting a rider with one. | skewbone wrote: | Rocket launches feel the same way. I got to see STS121 | launch from the VIP area at Kennedy Space Center a couple | of years back, and it felt like a continuous pressure wave | pounding on my chest until the rocket was above the clouds. | Crazy feeling. | eterm wrote: | > a couple of years back | | Sure feels like it; don't dare look at a calendar. | dylan604 wrote: | I know a camera guy* that decided he wanted to get footage | he'd never seen anyone else get. He got permission, but | everyone just shook their head and suggested it not being a | good idea (yes, please read foreshadowing there). This was | back in the day of using a BCSP over the shoulder camcorder | that brand new easily cost $75k with the particular lens | being used. He was behind both cars standing between them, | and when they took off, the forces were so violent it | caused the spinning heads in the camera to stutter so badly | the footage was unusable. Viewing the footage, the image is | fine right up to the point of start, then the image goes | crazy in the way only an analog system can do, then | stabilizes again when everything calms down. Not only was | it not usable footage, but he spent hours peeling/scraping | melted rubber off of everything. IIRC, the driver of one of | the cars was legendary John Force. | | * I swears it that it wasn't me in the "asking for a | friend" manner | jvanderbot wrote: | Does the engine weight count in that MJ/kg? | LeifCarrotson wrote: | No, I suppose not, but neither does the electric motor count | towards battery density. | | In top fuel events, they're burning roughly 20 kg of fuel per | second, so a 200kg engine still doesn't equalize the density | of that chemical fuel. | tim333 wrote: | I think probably the fastest accelerating ever car with a | driver was the Vanishing Point drag racer which did 0-60 in | about 0.25 secs using a peroxide rocket. Not very practical for | everyday transport though https://youtu.be/7QC6tymIvKA?t=209 | karamanolev wrote: | The differences are massive between road-going (on an asphalt | surface, ~1 friction coefficient), drag racing type (on a | drag strip, which has massively more grip, ~4) and rocket | driven (no friction at all, just the thrust/mass ratio) | vehicles. It should be clear they are in totally different | classes and advances in any of those classes are exciting and | worth mentioning, I feel. | Sharlin wrote: | Well, dragsters are laughably slow to accelerate if we're just | talking about "acceleration world record" without qualifiers. | (Assuming that "acceleration" here means "acceleration of a | ground vehicle with a human driver" is just as arbitrary as | "...of an electric ground vehicle...", after all. Actual | acceleration world records of macroscopic objects are in the | 10,000s of _g_ s...) | andbberger wrote: | i have an ultracentrifuge in lab that can do 100,000gs | sustained for hours | colordrops wrote: | What is it used for? | throwaway4PP wrote: | Centrifuges are used for separation. An ultra is usually | used for separating nominally-stable colloids (such as | fine nanoparticle colloids), and miscible liquids where | such high centrifugal force causes them to density | separate. | thelittleone wrote: | I was also curious and found this youtube [1]: | | Summary (found in video at 10:48) | | 1) separation of subcellular organelle (DNA/RNA) 2) | extract solutions in biological fluids from aqueous to | organic solvents 3) seperate lipid components 4) | pelleting of ribosomes 5) pelleting of macromolecules | | [1] https://www.youtube.com/watch?v=lRT_8nFc2Tk | HeyLaughingBoy wrote: | Ha. On a hunch I watched that video and hunch confirmed | in the first second: I used to work for those guys, but | not in the Centrifugation division :-) | jeffbee wrote: | Military-funded experimental railguns are in the 10s of 1000s | of gs. Are these the record-holders of whom you speak? | kragen wrote: | I'm thinking probably alpha-particle decay exceeds that by | a lot. | jeffbee wrote: | I imagine that's why the other person qualified their | remark as referring to "macroscopic" objects. | kragen wrote: | Hmm, good point. Maybe small objects not quite close | enough to a hydrogen bomb to be vaporized by the flash, | then? | Sharlin wrote: | Related: the "nuclear manhole cover" [1] (actually a 900 | kg piece of armor plate) which may have accelerated to | several times Earth's escape velocity over the course of | a few meters (tens of millions of g's which is | _definitely_ impressive for such a heavy object). It was | likely vaporized due to compressive heating before | escaping Earth 's atmosphere, however. | | (I'm rather amused by the idea that some manager type | evidently thought that a hunk of steel might contain a | _nuclear explosion_ in what was in essence a very large | cannon!) | | [1] https://en.wikipedia.org/wiki/Operation_Plumbbob#Miss | ing_ste... | kragen wrote: | A big enough hunk of steel can certainly contain a | nuclear explosion. | Sharlin wrote: | At 900 kg, we're talking about a fairly small hunk. | vizzier wrote: | Like the borehole cap on | https://en.wikipedia.org/wiki/Operation_Plumbbob Pascal-B | dtgriscom wrote: | If you can only accurately know the position OR the | momentum, is acceleration well-defined? | ben_w wrote: | Sure, ignore the position, just focus on the rate of | change of momentum with respect to time. | labcomputer wrote: | Well, that doesn't quite work either. Energy and time are | also conjugate variables, so there exists an uncertainty | relationship between them. | | And since you can relate energy to momentum in a well | defined way... | Sharlin wrote: | I think my "10,000s of gs" was maybe a slight | underestimate. A light-gas gun [1] can accelerate a | projectile to velocities of several km/s over a distance on | the order of a meter, giving an acceleration on the order | of 1,000,000 g by a quick calculation. | | [1] https://en.wikipedia.org/wiki/Light-gas_gun | lazide wrote: | Don't forget explosively formed penetrators! | Sharlin wrote: | Good point! | [deleted] | WalterBright wrote: | Top fuel drag racers already have traction control. The slip is | adjustable and getting it right is a big factor in winning. | jcampbell1 wrote: | The clutch slips for about 2/3 of the 1/4 mile. It is a huge | factor. | | My college motorsports team got to meet with John Force, and | someone suggested a flexible rear spoiler for variable | downforce. He was quick to note it likely would be faster but | would almost certainly get you killed. | jcims wrote: | I just saw a breakdown of a crash where the engine shut down, | allowing the clutch to stop slipping. That final clamp dumped | a huge impulse into the drivetrain and ripped the tires off | the wheels. (At least that's the way I understood it). | | Clay Millican has an amazing YouTube channel that brings you | behind the scenes of an NHRA top fuel team - https://www.yout | ube.com/channel/UClT3GT7hxLbNnypukfyxelQ/vid... | abfan1127 wrote: | its my understanding that the clutch designers are the | highest paid crew members. Choosing how the clutch performs | is the critical piece to winning, based on track | temperatures, weather conditions, engine performance, etc. | twobitshifter wrote: | Think like a purpose built dragster. You only need enough | energy for 1.5 seconds and that's as long as the wiring needs | to take the current for. I think a purpose built electric | dragster might be lighter just because of the parts you don't | need. The motors may reverse the energy weight savings | lazide wrote: | As long as the copper doesn't vaporize until the end, we're | all good? | bumby wrote: | Small nit: | | > _detonating_ | | Should be deflagrating because the ICE flame is designed to be | subsonic. | slowhand09 wrote: | Not sure this applies here Top Fuel engines are nearly | burning a liquid rather than a gas. And yes I know you can't | really compress a liquid. The typical ratio is 1.7 pounds of | air to burn 1 pound of Nitromethane. It burns slower than | gasoline tho. And normal gas engine runs in the vicinity of | 14.5:1 air to fuel. | bumby wrote: | > _And yes I know you can 't really compress a liquid._ | | Sure you can, it's what the bulk modulus measures. | | You may be right. My assumption is that, by definition, a | detonation is an uncontrolled pressure wave and controlling | the pressure in an ICE cylinder is a big deal that a lot of | engineering goes into. As you point out, the major benefit | to nitromethane is that is requires less air because it | brings it's own oxygen. So the size of the combustion | chamber isn't as much as a limiting factor. I don't think | it's intent is to change the flame regime, though. It just | crams more energy into the cylinder. | lazide wrote: | Keep in mind, there is a very common type of ICE that is | really a IDE (internal detonation engine) - diesels. | | With strong enough engines, detonation isn't ruled out. | Someone wrote: | > I wonder what the record is for a vehicle that can pick up | electric energy from a tether/rail/overhead wire...though | cables that can carry megawatts of energy are probably pretty | heavy. | | For a one-off design, those cables could be very short. You | could even have a very small pantograph | (https://en.wikipedia.org/wiki/Pantograph_(transport)) | | I am not sure the end result would be faster, though. You'll | need grip to get up to speed, and starting from a standstill, | you won't get that from aerodynamics. you'll need mass. Take | away the batteries, and you may have to add a similar mass in | dead weight (could be used to add a good Faraday cage to | protect the driver from mishaps with the electricity supply) | karamanolev wrote: | I think what you care about is to have enough power to be at | the limit of the grip of (all) your tires. If you are | heavier, you need more power to reach at point. If you do | have enough power, then it's all about maximizing grip - | tires, surface, downforce and so on. | | More mass and more power are roughly equivalent to less mass | and less power, if the above holds. Maybe even with less mass | it's easier, since you can produce significant downforce with | smaller wings. | rainbowzootsuit wrote: | A cable that can carry 1.21GW is only about the diameter of | your finger. | 3000000001 wrote: | Great Scott! That's surprisingly small. In all seriousness | though, that's probably not at useable voltage, you might end | up with a 5 ton transformer on the car if you delivered 33kV | in such a small cable. | mrb wrote: | << _~40 MJ /kg for gasoline and 0.4 MJ/kg for a lithium ion | battery_>> | | That is correct. Out of curiosity, I looked it up and for the | Tesla Plaid that's 0.65 MJ/kg (or 181.5 watt*hours per | kilogram) | | But my follow-up question is: if gasoline has an energy density | about 100 times higher (well, 60 times) why are dragsters not | even faster? This Stuttgart EV does 0-100 km/h in 1.461 seconds | (1.87g), and dragsters do it in 0.8 seconds (3.42g). It sounds | like with such a phenomenal energy density, gasoline-powered | dragsters should be able to accelerate at much more than 3.42g, | maybe 10g, or more. Intuitively this indicates that the | bottleneck isn't energy density, but mechanical factors (gears, | traction, etc). Therefore if battery energy density can | increase just a little more, maybe to 2 or 5 MJ/kg, this may be | sufficient for EV to be able to beat dragsters. | dreamcompiler wrote: | > you're looking at roughly a factor of 100, with ~40 MJ/kg for | gasoline and 0.4 MJ/kg for a lithium ion battery | | If you only care about acceleration, energy density doesn't | matter very much. What matters is _power_ : The rate at which | you can move energy from the storage medium to the wheels. In | that respect a capacitor-powered dragster could probably smoke | a top fuel dragster, even though the energy density of | capacitors is pretty lousy. No idea if anybody has tried to | build a full-size capacitor-powered dragster. Or if any human | would be brave enough to drive one. | LeifCarrotson wrote: | Having investigated some of these questions with respect to | quadcopters and micro-mouse 'bots, the power density (both in | mass and volume) of capacitors is pretty terrible. Whether | you're talking about aluminum electrolytic traditional | capacitors or double-layer supercapacitors, they're inferior | in most cases to a lipo. That's especially true if you're | open to high-discharge 50C or 75C lipos, which can dump their | entire energy capacity in ~60 seconds. | | If you only need a few milliseconds of 'zap', yeah, a | capacitor bank is great. It's the only option if you need to | do that more than a couple hundred times in the life of the | battery; a chemical battery will wear out but a capacitor can | last for millions or billions of charge/discharge cycles. | | But even a time as short as 1.461 seconds is probably on the | far side of the inflection point where capacitors make sense. | | If you like, run through the options on Digikey: | | https://www.digikey.com/en/products/filter/electric- | double-l... | | ex: | | https://www.eaton.com/content/dam/eaton/products/electronic-. | .. | | Also remember that an ultracapacitor is about as far in | behavior from a physicist's ideal plate capacitor as you can | get - they're not linear, they have highly significant | internal series resistance... | TheSpiceIsLife wrote: | Also remember that top fuel dragster engines only run for a | handful of seconds before they need to be rebuilt, and will | be destroyed in a non-recoverable way after more than a few | handful of seconds of run time. | | I'm not sure if anyone is building electric dragsters with | run-once components, or how that might change assumptions? | dreamcompiler wrote: | I was thinking more in terms of ordinary capacitors than | supercapacitors because the former are vastly superior in | terms of power density. However, ordinary caps are so poor | in energy density that it just might matter, even for a | very short duration energy dump application. | | IOW I'm not sure there's enough volume in a dragster to | meaningfully power it with ordinary caps. But if there is, | it would be a very quick car. | greggsy wrote: | > Or if any human would be brave enough to drive one. | | From the perspective of being that close to being fried, or | with respect to the acceleration? | | To be honest though, I still think it's amazing that people | casually handle extremely flammable and volatile hydrocarbons | whenever they visit the gas station. The safety ecosystem is | very well tuned, albeit after a hundred+ years of accidents | and research. | dreamcompiler wrote: | > From the perspective of being that close to being fried, | or with respect to the acceleration? | | I was thinking the former. One does not casually fuck | around with big capacitor banks and live to talk about it. | ccn0p wrote: | anybody else let down from the video? there was no just simple | observer perspective in real time. maybe because it would have | been funny going really fast for 20 meters. | kleiba wrote: | Amazing: there's one girl on the team! | moritonal wrote: | That video was brutally edited. I guess it's marketing but it | somehow manged to be two minutes long and reduced the actual | content to look like a toy car slowly launching without any frame | of reference before quickly cutting to a bird? | | Like, watch Mythbusters or Slow-mo guys and try again. | renewiltord wrote: | https://youtu.be/xjDK0LhKkMs?t=85 to cut to the chase. It's | hard to discern from a routine Tesla with the pedal down | perhaps because we're bad at telling small amounts of time | apart. | kube-system wrote: | And it's hard to judge speed from a video anyway. | | https://youtu.be/54Oy75Bnu_Q | renewiltord wrote: | Good one. The static camera shots from distance with human | references are probably better on this video anyway | https://youtu.be/bO7HlsAbhQk?t=50 | Nition wrote: | Video games use this trick all the time. When the player | sprints or gets a speed boost, give them some actual boost, | but also increase the FOV. | [deleted] | Krasnol wrote: | My thought exactly. | | There is not a single normal shot of that car accelerating from | outside the car so you can actually see it accelerating fast. | It's infuriating. | | I guess the marketing department of the university did the | video editing... | spinningslate wrote: | came here to say this. I mean, if the car actually did break a | record - and I'm not questioning that - then _actually showing | it happen_ , in a visually recognisable way, might be, you | know, a good idea?!? | | Dubious video aside, congratulations to the students. It would | be great to see/hear what they did to achieve it. For example: | I'd imagine traction off the line would be a big challenge for | something so small (and presumably light). They did warm the | tyres (video at least showed that) but what else? Traction | control? Most likely yes. Anything novel in its implementation? | | Be good to get some detail behind the result. | LeoPanthera wrote: | Mythbusters isn't a great example, to the point that there are | re-edited episodes floating around that remove all the | superfluous teasers, "coming up"s, and unnecessary repeated | shots. | | https://www.reddit.com/r/smyths/comments/8gix4w/streamlined_... | topspin wrote: | This is why I, and you, read the comments first. | marginalia_nu wrote: | Maybe I'm misremembering, wasn't Mythbusters like | | https://tenor.com/view/truck-speed-loop-gif-17654345 | Confiks wrote: | Zeno's Truck. | Dylan16807 wrote: | That wasn't mythbusters. | | https://www.youtube.com/watch?v=3JtZDDQga4o&t=85s This | example seems just fine. | mwint wrote: | Usually they would do that, cut to commercials, and then show | the full thing in slow motion. Irritating, but not quite the | same. | incahoots wrote: | I hate you for this but this gif will never not be | entertaining | Animats wrote: | Yes. There's so much slow motion and fast motion there's no | sense of how fast the thing accelerated. | | Admittedly they're trying to dramatize something that took 1.2 | seconds, which is hard. But still. | jws wrote: | That's an average acceleration around 2g. This seems beyond the | limits of tires and friction. Do aerodynamic down forces kick in | fast enough to make more force usable against the road at these | relatively low speeds? Do the tires have more than static | friction going for them (say, fine scale interlocking with the | pavement)? | | Drag racers can do 3gs, but that's at higher average speed. | agloeregrets wrote: | Aero might play in a tiny way at the 40-60 MPH space, not | meaningfully enough. | | As for tires, no actually you can go much further than this. | The big detail is wear and heat caused by tire softness and | pressure. Road car tires can't enable 0-100KPH much faster than | 1.9s or so purely because they can't be so soft as crusing on | the highway would cause excess wear(practicality), heat | (Danger), and friction(Range). | | Drag Racers can accelerate way faster, 0-60MPH in .8s. | ihunter2839 wrote: | The aero packages for these vehicles create a pretty | significant amount of downforce at relatively low speeds - | for example, our car last season produced ~140 lbs of | downforce at 35 mph. | | Edit - A lot of that comes from the rear wing though, which | the green team didnt run for this particular event. | Karstographer wrote: | These formula student/fsae cars have aero packages which tend | to be designed around 30mph average track speeds, so they will | get contribution from that, especially in the latter half of | the run. Even so, the tire friction involves both physical | interlocking due to deformation and chemical adhesion. | | You can see the tire warmers in the video being removed in | addition to their approach burnout which imparts additional | heat into the tires, so that the tires more effectively stick | to the ground. | | For all of the questions about why they don't compete with | dragster techniques, the student race series they participate | in has very strict regulations regarding vehicle layout which | forces them to be more of an autocross car, these kinds of | (heavily couched) records being produced are really somewhat | incidental. | ihunter2839 wrote: | Although the other comments are correct about the 30mph | optimization for the aero package, this car uses active | underbody aero (aka, fans) to create additional downforce even | when at a standstill. See the recent runs of the Speirling at | Goodwood festival of speed to see a purpose built "fan car" in | action. | | Interestingly, this setup wouldn't be allowed due to rules in | Formula SAE in the US but is legal in the german competition | cause those teams are just built different. | | Edit - Quick plug! If anyone is interested in supporting FSAE | and the awesome engineering that goes into these cars, I am a | member of the San Jose State team and our aero team is in need | of HPC access to run their CFD simulations. My email is in my | profile. Cheers. | raydiatian wrote: | Ohhh, it's 100 kmh | notum wrote: | 257HP on a vehicle that weights less than some people. | Exceptional! Congratulations to the team. | slowhand09 wrote: | I'm surprised you had to dig a bit to see it is in KM. A US | audience might assume MPH. | zwieback wrote: | Yay, my Alma Mater - the city of Mercedes, Bosch and Porsche. | You'd expect some cool car stuff coming from there. | js2 wrote: | 0-100 kmh (~ 62 mph) in 1.461 seconds exposes the driver to ~ | 1.94 g. | | For reference, a top-fuel dragster can do 0-100 mph (~ 161 kmh) | in about 0.86 seconds, exposing the driver to nearly 5g. | | https://jalopnik.com/the-fastest-0-60-time-a-person-could-ac... | | http://www.procato.com/convert/ ___________________________________________________________________ (page generated 2022-10-12 23:00 UTC)