Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Bugatti has broken the 300mph barrier

topgear.com

Post reply on HN
Print view View original

291–300 of 302 posts

Re: Bugatti has broken the 300mph barrier

#291

Post by ollie87 »

beatgammit wrote: post #250
jfk13 wrote: post #138

Earlier quoted context omitted.

> Personally, I tend to cruise at an indicated 100mph In the UK? OK, at least it's clear what you think of the law. Personally, I hope you get nailed for it. That sort of contempt for both the law and other road users ought to be penalised. (Maybe you only cruise on empty motorways at 3 AM, and so that makes it acceptable...?)

In the US, I often drive in roads with a posted limit of 80mph going ~100mph, and even then I get passed sometimes. It's not inconsiderate to other road users if I make sure to pass and yield appropriately, though it's certainly a violation of the law. And yeah, I think the law is stupid. I believe that we should eliminate speeding tickets and have police only enforce "reckless driving". Going the speed limit could b…

That's basically how it works on the Isle of Mann.

Re: Bugatti has broken the 300mph barrier

#292

Post by ollie87 »

SmellyGeekBoy wrote: post #86
zone411 wrote: post #69

Earlier quoted context omitted.

It sounds like you don't know about track days or drag strips. That's the way to enjoy a car that goes faster than 150km/h fully. A 300mph Bugatti is still way above any speed you'd reach, though.

Even in that case a much lighter (and cheaper!) car like an Atom or Caterham will be a lot more fun than one of these hulking great monstrosities. Often faster as well, depending on the track.

Launching an Atom or Caterham with big power is incredibly hard for most people, even for those who own them. Not really a drag strip car, more a club circuit vehicle.

Re: Bugatti has broken the 300mph barrier

#293

Post by rconti »

hazeii wrote: post #158
bartread wrote: post #79

Earlier quoted context omitted.

I ride bikes and from a practical standpoint, along with small size and manoeuvrability, the acceleration (a result of torque) is one of the most useful attributes. Much moreso than top speed, or even speeds significantly in excess of the posted limits. Bikes don't tend to have high torque in general, but their light weight and gearing are designed to maximise what torque they do produce. This means there are quite a…

Bikes like Harleys and BMW twins have plenty of torque, where bikes like Kawasaki Ninja's major on power (peak torque at high revs). Hence Harleys and BMW's are first off the line at the lights (no need to build revs) but the Ninja's will come steaming past seconds later. There are some fun youtube videos demoing bike performance, e.g. Ninja H2's doing 0-250MPH in 26s [0], outdragging a Bugatti [1] and outpacing an F…

To a close approximation, it doesn't matter.

Rev engine, slip clutch to launch, versus slip clutch and immediately begin putting on the power.. no matter what, you need to engage the clutch and add throttle. The motor has so little mass it's not like it takes a long time to get it spinning before dumping the clutch on a low-torque motorcycle, and you can rev before the green.

And regardless of what you're riding, you'll be across the intersection before most cars have even begun moving.

Re: Bugatti has broken the 300mph barrier

#295

Post by Piskvorrr »

adrianN wrote: post #30
tialaramex wrote: post #13

It's futile to actually have road-legal cars that go this fast because you can't do very much useful with the speed. This is much too fast for the human operator (driver) to safely react to things outside the cockpit, which is why for example Britain owns trains capable of 140mph in service but deliberately limits them to 125mph. Tests suggested drivers couldn't be relied on to reliably observe and react to a linesid…

A train going faster than 25mph or so is already too fast for the operator to react (braking distances are huge!), so I doubt that the top speed is limited for that reason.

Do not underestimate E=mv^2 ; hitting something at half the speed means quarter of the energy. Case in point: at a speed of 135 km/h, driver sees a bridge falling across the tracks half a km ahead, engages brakes, hits bridge at 90 km/h. By reducing the speed by 1/3, the total energy of the impact was reduced over 50%. There were 6 dead in that crash; without braking, the entire train plus 400 pax would have been blown to bits. https://en.wikipedia.org/wiki/2008_Stud%C3%A9nka_train_wreck

Re: Bugatti has broken the 300mph barrier

#296

Post by vonseel »

docdeek wrote: post #104
vonseel wrote: post #100

Earlier quoted context omitted.

Hmm, I'm not a biker but I always assumed your legs determine statistics like acceleration on a bike. Learn something new everyday...

I suspect that bike was short for motorbike - not too many humans can do 0-60 in 3 seconds. ;)

Sounds right!!!!

Re: Bugatti has broken the 300mph barrier

#297

Post by colechristensen »

n1000 wrote: post #142
colechristensen wrote: post #130

Earlier quoted context omitted.

The fastest Tesla seems to beat the stock version of the Bugatti in question by about a quarter second from 0-60 (2.25s vs 2.5s) but the Bugatti handily beats the Tesla in the 1/4 mile by half a second and 25 mph, so the Tesla wins at acceleration for the first second or so. The torque curve on the Bugatti starts out lower for the first 1-2k RPM and then sticks at a significantly higher torque that seems artificially…

These fancy supercars come with "launch control". A mechanism that will rev in a high range (charging the turbos) and then release the clutch with full torque. I wonder if that helps... https://en.wikipedia.org/wiki/Launch_control_(automotive)

Yeah the results on a dyno won't match the actual torque on the wheels when launching. It would be interesting to see a graph of how that happens. Torque vs. Time and RPM vs. Time on a two y-axis graph for an actual launch (maybe you could put sensors on the axles)

Re: Bugatti has broken the 300mph barrier

#298

Post by et2o »

Phillipharryt wrote: post #253
et2o wrote: post #236

Earlier quoted context omitted.

I hate to nitpick, but a Prius isn't a great comparison since they have pretty good drag coefficients.

Yeah I did clarify it's not the worst, it's a smooth vehicle but it's got pretty bad turbulence at the rear due to that flat back, so it's no aerodynamic masterpiece. I only use that comparison because it's a bog-standard car and can't get anywhere near 300mph, so it might surprise people to know it has better aerodynamics.

Not sure what you mean... A Prius is actually one of the single best production cars around in terms of aerodynamics (Cd around 0.24).

That stubby tail is actually done on purpose because it reduces drag, not increases it as you claim. A lot of aerodynamics are pretty counterintuitive. Look at the big table of drag coefficients here: https://en.m.wikipedia.org/wiki/Automobile_drag_coefficient

For the Bugatti, they probably weren't going for an ultimate low drag coefficients. They need to make sure their giant engine is getting enough air, which leads to lower performing shapes. Related, they also will want a lot of downforce to make sure the car stays on the road at high speeds; to do this they build a relatively non-aerodynamic car.

Re: Bugatti has broken the 300mph barrier

#299

Post by rurban »

Svip wrote: post #33
beambot wrote: post #31

Earlier quoted context omitted.

> The "obvious" upgrade ... What's stopping the trains from operating autonomously?

Drivers are still a lot better at spotting pedestrians on tracks than autonomous systems. Autonomous train systems already exists, but those are completely enclosed systems, like a city metro system. Not a system where speeds reach 200 km/h, or even 100 km/h.

The ability to spot pedestrians on tracks is something you want to avoid.

First you cannot break it anyway that fast. Second, rolling over suicidal pedestrians has a high psychotherapy cost. Driver-less trains not.

Re: Bugatti has broken the 300mph barrier

#300

Post by Phillipharryt »

et2o wrote: post #298
Phillipharryt wrote: post #253

Earlier quoted context omitted.

Yeah I did clarify it's not the worst, it's a smooth vehicle but it's got pretty bad turbulence at the rear due to that flat back, so it's no aerodynamic masterpiece. I only use that comparison because it's a bog-standard car and can't get anywhere near 300mph, so it might surprise people to know it has better aerodynamics.

Not sure what you mean... A Prius is actually one of the single best production cars around in terms of aerodynamics (Cd around 0.24). That stubby tail is actually done on purpose because it reduces drag, not increases it as you claim. A lot of aerodynamics are pretty counterintuitive. Look at the big table of drag coefficients here: https://en.m.wikipedia.org/wiki/Automobile_drag_coefficient For the Bugatti, they pr…

Ok I hate to do this, but you're wrong about the tail reducing drag instead of increasing it. The rear of the prius has a design feature to reduce the effect of the turbulent wake created by having a flat rear, but it still has a large vertical surface at the rear creating a lot of wake. You can clearly see this in a wind tunnel.

https://www.youtube.com/watch?v=Ov0iNPfs-WM

Post reply on HN