RE: Ariel Atom 500 V8 Announced

[STASH]

think you have had too much beer my son does mummmy know your on here

[Gizmo535]

Nurse, fetch the screens. We've got a live one here!

Oh, and here's some punctuation: ,,,,:::;;;;''''"""" Your computer seems to have run out.

[STASH]

so not only are you an idiot you are an idiot with an education i applaud you my friend, we are only talking about cars but why is it a nervous, highly strung, little man like you always has to make it personal!

[Miguel]

Phisp said:

sniff petrol said:

damiwi said:

Power at Flywheel (BHP) : 500
Weight without Driver (KG) : 500
Power to Weight Ratio (BHP Per Ton) : 1016.05
0 - 60 (Secs) : 2.70
0 - 100 (Secs) : 6.08
60 - 100 (Secs) : 3.38
Quarter Mile (Secs) : 10.80
Terminal Speed (MPH) : 133.30
Drag Strip Quarter Mile (Secs) : 10.70
Drag Strip Terminal Speed (MPH) : 134.87

Where did you get the acceleration figures from or are they a computer prediction?

http://www.letstorquebhp.com 

sniff petrol said:

Also, isn't 500bhp in a 500kgs car 1000bhp/tonne?

At best, take into account transmission losses and driver weight and it is going to be less - not more as this website suggests

Transmission losses have nothing to do with it. Neither does driver weight. Whenever power to weight ratios are discussed or compared, the figures used are quoted power (DIN, SAE net, etc., which don't include such losses) and the car's curb weight with no driver. Obviously, transmission and other losses and driver weight all factor into the real world acceleration, but power to weight figures are calculated without those realistic factors for practical reasons, thus, if two cars have the same power to weight ratio, all else being equal, the heavier one should accelerate more quickly because with the driver in the car, its true power to weight ratio will be less affected by his weight. I assumed that the reason they came up with the figure of around 1016 hp/ton is that the car either produces slightly more than exactly 500 hp or weighs slightly less than exactly 500 kg or both. Then I read the post that explains all the different tons. ;-)

Miguel

[Miguel]

baby g said:

NicNZ said:

NiallOswald said:

otolith said:

NiallOswald said:

One advantage heavier cars do have is traction, which is directly proportional to the force exerted on the tyres by the vehicle's mass.

Fmax=μR, true, where R=mg. But F also = ma, a = F/m, amax = (μmg) / m, so mass cancels out.

Good point. More than that, good point which suggests (in this simplistic model) that acceleration is limited by μ given that g is a constant to all intents and purposes. Interesting...

I'm struggling to find a definitive answer for how μ depends on factors such as tyre width, diameter, temperature and rubber compound, but the indication is that the Fmax=μR model falls apart in the real world...

Here goes, first post, hope it's helpful (and spelt right!). I can't help with the relationship between μ and tyre width etc, but for 2wd cars one reason the relationship falls down is that the in the equation R=mg, m is not the complete mass of the car - only the mass carried by the driving wheels. Also, dynamic effects (weight transfer) have to be considered. That is why a rear wheel drive car generally gets better traction than fwd - accelerate, more force acts on the rear (driven) wheels, so there is less chance of wheelspin.

These effects are frequently mentioned in relation to 911's - rear engine means significant rear weight bias, and hence excellent traction during acceleration.

Agree with the points above. If you consider F=μR model, different tyre width/pressure/diameter have no effect as increased rubber on the road is balanced by the reduced pressure caused by force being spread over a larger contact area. The key influence is the rubber compound in the tyre and the composition of the road surface (inc temp etc).

It's interesting that the F=μR equation is normally used to describe dynamic friction of two surfaces sliding over each other, and it is usual to have a higher static friction when the two surfaces are at rest. The point of contact between tyre and road is not sliding (except during wheelspin which is acknowledged as a poor way of accelerating). There are a number of other dynamic effects going on in a rotating rubber tyre, but the principle of static friction is there.

What you see in real life is due to the roughness of the road surface you actually get a meshing effect at the point of contact. This gives you a small direct drive effect (at the very small scale of roughness in the road) similar to a pinion on a rack such that the acceleration observed is greater than with μ=1. This explains wider tyres/lower pressure actually increasing traction.

In other news, 500bhp in an Atom? Blimey. I like.

Sorry, otolith, but your physics calculations don't fly. Mass does not cancel out, and it is relevant when it comes to traction.

otolith said:

Fmax=μR, true, where R=mg.

Looking at your equations, I'm assuming that you're saying that
Fmax (frictional force) = μ (coefficient of friction) x R (normal force)

That is correct, and it's that friction that produces what we call traction.

otolith said:

But F also = ma, a = F/m, amax = (μmg) / m, so mass cancels out.

This is where you got lost. It's true that F (force) = m (mass) x a (acceleration), but that has nothing to do with what you wrote before. The force produced by the car accelerating, defined as the product of the car's mass and its acceleration, has nothing to do with the frictional force acting on the tires, even if you happen to use an F for both.

This paragraph is what I'm adding now that I'm editing this post due to my boneheaded statement above. Everything above is as I originally wrote. Now that I'm awake and have gotten over not having seen so much math in close to twenty years, I realize what you're trying to say. When you said F=ma, you were talking about the normal force (R) and the acceleration of gravity, not the car accelerating and its corresponding force. If you take the fraction of the total weight of the car that is over its driving wheels and calculate its corresponding mass by dividing it by the acceleration of gravity (g), it cancels out as you showed. Let's use m to refer to just the corresponding mass over the driving wheels to make it easier to follow, as you did. The reason the mass cancels out is that you solved it for acceleration. The acceleration in your example is g. Of course mass canceled out. You just proved that gravity accelerates any object at the same rate, regardless of mass, provided you ignore aerodynamic drag. But what you're trying to show is that the friction is independent of the mass or weight of the car. Again, F=μR=μma where m is the percentage of mass of the car that gravity is acting upon to put a force on the corresponding wheels and a (acceleration) is g or gravity. Again, μ and g are constants and the frictional force, or F is directly proportional to the amount of weight over the driving wheels, therefore mass is relevant. Solving for a, which is g just shows that gravity is constant. Everything below this paragraph is unedited.

Also, as NicNZ pointed out, the weight of the whole car (the whole car's mass x gravity) is not what is producing the normal force on the tires, so the two m's are also different.

Of course, to make matters worse, how much weight is over the driving wheels when the car is static is important, but it's only a starting point. FWD cars have a large percentage of their weight over the front wheels, which makes them great for driving on snow (for 2 wheel drive cars).

The problem is that when a car is accelerating hard, its center of gravity shifts to the rear, essentially making the front of the car lighter and the rear heavier. That's why under hard acceleration, a FWD car always loses traction. Rear drive cars actually gain traction as they accelerate. This compounds the weight that's already there and does make a difference to the traction of the car.

Of course, you can't control that cg shift. What you can control is the static weight distribution of a car, so the more rearward the weight bias of a RWD car is, the better the traction--all else being equal, of course.

Thus, among RWD cars, the ones with the least traction are usually front engined with a conventional transmission, followed by front engined cars with a rear transaxle, though the difference between those two is not huge, followed by mid engined cars. Rear engined cars, such as the Porsche 911, have great traction and thus acceleration to lower speeds that is usually excellent for their power to weight ratio because they waste very little time putting power to the ground. At higher speeds traction plays a much smaller role in acceleration.

Miguel

Edited by Miguel on Saturday 1st March 14:37

[Miguel]

Los Angeles said:

Excellent post, Miguel.

Thank you. (blushing)

Miguel

[Miguel]

Los Angeles said:

Yes, the second post. You'll see from my profile my entusiasm for the Griffith, but the traction from the rear 993 I own is of a totally different level. It does, however, suffer from lightness of nose once you move through the 100 mph mark, and to the novice, the experience can be unnerving.

Yes, earlier 911's are famous for that. I'd love to drive a Griffith, as well as other modern TVR's, but living in the US, it's not possible, at least not without traveling. Then again, you also have the greatest car ever made--the MX5--not that I'm biased.

Miguel

[RobM77]

Gizmo535 said:

STASH said:

all this is well and good but if you want real excitment get a bike end of story

A bike would be DESTROYED by an Atom - any Atom - around any track you care to choose. Cornering speeds are everything.

Personally I think this sort of thing should be applauded: British engineering at its finest. I mean, what utter, brilliant, incredible, fantastic lunacy. Top work [/bik

bikes only lose to atoms and porsches when MR clarkson has anything to do with it ive seen a GSXR BEAT A RADICAL AND A BLADE BEAT A LAMBO HANDS TOWN ON TV

Lambos are luxury GTs really, so let's not worry about that; I bet you I could get a Caterham to go faster than a Goldwing . A Radical would make mincemeat of any road bike in any normal track situation I can assure you!!! The test you are referring to took place on the Silverstone circuit for bikes, which has a chicane after Luffield (like the one they put in at Mallory). This chicane is almost too tight for a car, and it creates a 0-100 sprint at the end of the lap, which the bike wins. On any other circuit (including the normal Silverstone), if you look at the lap times, a decent road bike like an R1 or 999 is beaten by an Atom or Caterham let alone a Radical!!

Saying a bike is quicker than a radical is rather like saying that a man can run faster than a giraffe if you include a limbo challenge halfway round the course

Edited by RobM77 on Saturday 1st March 11:53

[jon b16]

atom-ick said:

I have to say i am somewhat disenchanted by this. I love all sorts of lightweight sports cars - Caterhams, Atoms, Radicals etc. and have owned both a 7 and an atom (as well as all manner of other performance cars from mark 1 golf GTI's in my youth through to a 996 gt3)

I just feel that Caterham where being a bit maverick with their V8 "Levante" and i can't help but wonder if this is simply a knee jerk reaction from ariel. I mean, up until now atoms have always been great fun, mainly for having a bonkers amount of power, where caterhams have been a bit down on power, but made up for it through better, more instinctive handling.

What i am saying is that the Atom's headline was always the bonkers power, where as the Caterham's was super human handling. With a 550 bhp V8, Caterham can have it's cake and eat it - smashing the atom on Power and handling.

Edited by atom-ick on Friday 29th February 09:38

It was not a knee jerk reaction - had you not considered that Ariel may have already been developing this for some time?

I too have been fortunate enough to own/ed a number of wonderful cars inc Caterham R400, Radical SR3 Supersport, Ariel Atom 300, GT3RS - have driven many, many more

Maybe it was the variant of Atom you had but the MKII with the right suspension package is an extraordinary car, the Atom 3 an evolution of this. Personally, i see little difference in the intuative handling characteristics of both car. The caterham has more weighty feel to the steering, only a minor amount more - the Atom has the most extraordinary balance - in a progressive o/steer biased.....so, so rewarding.

Any car with 1000bhp/ton being used on the road is plain silly imo. Its is all about headlines and there will be plenty. The biggest headline will be the Autocar 0-100-0 shoot out. Which will win? Caterham, Atom 500 or Caparo T1. My money is on the Atom and for one simple reason. It has INCREDIBLE traction as all of the weight is over the rear axles. The Caterham has always had a problem with not having enough weight over the rear axle which impacts is standing start performance.

Anyone knocking the handling of the Atom is talking rubbish - they either don't know what they are doing or are driving an early car...... remind me how long has it taken Caterham to evolve their cars......was it 40/ 50 years. The Atom is a staggering achievement in such a crazy short period of time.

Here's a couple of vids of me in the 300...

straight line performance.... 0 to 90mph in 5.3secs - this vid is from 0-80mph (on private road of course )
http://www.youtube.com/watch?v=RoLhzTFoS10

First time in the atom on track - you can hardly criticise the handling can you?
http://www.youtube.com/watch?v=V2uvtSsZ7DI

[Bruce Fielding]

It's going to be bonkers.

It's going to be undriveable (except with the launch and traction control working)

It's going to be lots of money

It's going to sell 20 (probably mostly to people who won't actually appreciate the dynamics of it)

It's going to win the Autocar challenge - which I suspect is the one of the two reasons for its existence

It's going to generate lots of media coverage (q.e.d.) - which is the other reason



And it will be as much fun as a bike - as for comparitive speed, it'll probably be slightly slower to 30mph, but definitely faster around corners.

And as for a knee-jerk reaction to Crates Levante, if you think Ariel picks up Autocar one week and sees what Caterham are doing, makes a phone call and hey presto two weeks later the engine appears in an Atom, you sorely misunderstand the practicalities of car production.

[JonRB]

I really don't want this to turn into a Bike vs Car religious war, but I thought the EVO magazine feature on the TT a few months ago where they took an Atom over there was quite fair. It's generally acknowledged that a bike's far superior power-to-weight ratio is going to make it faster in a straight line in ideal conditions, whilst a car's vastly wider track, tyre contact area, swept brake area and stability is going to make it corner harder and brake harder.

You can vary the conditions and environment however you wish to achieve the desired outcome depending on whether you want the bike or the car to "win", which makes any comparison largely irrelevant.

In the Isle of Mann article in EVO the conditions were fairly damp and the Atom romped away in a straight line and continued to hold an advantage through the corners and under braking, but that is more down to the fact that the Atom closes the gap on the power-to-weight ratio over a bike and also in those wet conditions the extra rubber it can lay down makes a big traction difference. In dry conditions I would predict a bike would still have the advantage.

As for the Atom 500 V8, I would think that the difference in power-to-weight ratio would be almost non-existent (you'll have to forgive me for not being totally clued up on a bike's P2W) and, with the traction control, I can't see many bikes being able to hold a candle to it.

[Bing o]

Bruce Fielding said:

It's going to sell 20 (probably mostly to people who won't actually appreciate the dynamics of it)

Yeah, cos I can see all the footballers wives chopping in their Cayennes for that...?

[RobM77]

jon b16 said:

Here's a couple of vids of me in the 300...

straight line performance.... 0 to 90mph in 5.3secs - this vid is from 0-80mph (on private road of course )
http://www.youtube.com/watch?v=RoLhzTFoS10

First time in the atom on track - you can hardly criticise the handling can you?
http://www.youtube.com/watch?v=V2uvtSsZ7DI

Those are some great videos there. Very smooth driving - in fact so much so it's hard to tell how close you were to the limit How close were you to the limit, and how to they handle if you're going for a quick lap?

[glazbagun]

chris7676 said:

This is a bit insane. Aerodynamic issues will limit its high speed potential I bet.

The more interesting question is- what gives way first- the aerodynamics, or your face?

[jon b16]

RobM77 said:

jon b16 said:

Here's a couple of vids of me in the 300...

straight line performance.... 0 to 90mph in 5.3secs - this vid is from 0-80mph (on private road of course )
http://www.youtube.com/watch?v=RoLhzTFoS10

First time in the atom on track - you can hardly criticise the handling can you?
http://www.youtube.com/watch?v=V2uvtSsZ7DI

Those are some great videos there. Very smooth driving - in fact so much so it's hard to tell how close you were to the limit How close were you to the limit, and how to they handle if you're going for a quick lap?

Cheers - 1st time in the car on circuit so i reckon there was a fair bit left in the car - especially under braking

[RobM77]

jon b16 said:

RobM77 said:

jon b16 said:

Here's a couple of vids of me in the 300...

straight line performance.... 0 to 90mph in 5.3secs - this vid is from 0-80mph (on private road of course )
http://www.youtube.com/watch?v=RoLhzTFoS10

First time in the atom on track - you can hardly criticise the handling can you?
http://www.youtube.com/watch?v=V2uvtSsZ7DI

Those are some great videos there. Very smooth driving - in fact so much so it's hard to tell how close you were to the limit How close were you to the limit, and how to they handle if you're going for a quick lap?

Cheers - 1st time in the car on circuit so i reckon there was a fair bit left in the car - especially under braking

I'd agree, yes; quite a bit left under braking, but also in most of the corners. Have you had a chance to push it yet on track and see what it's like at the limit?

[Miguel]

Los Angeles said:

I sometimes wonder why one needs anything more expensive than an MX5. After all, top down, a sports car gets uncomfortably windy and noisy at speeds over 50 mph. (How rear passengers in four-seat rag tops fair is a mystery.) Therefore, a powerful engine isn't necessary, a flexible one will do. Mate that to superb chassis and a slick gear change ... and perfection. I admire the Ariel Atom a lot - not driven it fast, and only one drive - lightness taken to the extreme, but it's really a track car even if a few tough it out as a ride for the daily commute. I'd hate to be caught in a Scottish rain storm and have to overtake a big rig chucking buckets of spray at my non-existent windscreen. (Windshield.)

I hear ya. When I'm driving my MX5 and am about to get on the highway, I'll either put the top up before getting on, or I'll leave it down and put the windows up, otherwise it's too noisy and windy, as you said.

I certainly appreciate many cars that are more expensive than mine, but I'm impressed by how much fun the MX5 is and what Mazda has accomplished with this car. I'm also disappointed when I drive a car that is more expensive but not as enjoyable to drive. I do wonder what the MX5 would be like with more power, as much as, say, 100 more hp.

I'd love to have a 3.0 Duratec V6 powered Miata/MX5, like the prototype Mazda built a few years back. 240 hp (as that engine produced in the Jaguar S-type) would be sweet in my car. That would yield just over 220 hp/ton, which is why I simply don't get this 500 hp Atom. To me, it looks like an exercise in chasing numbers.

Don't get me wrong: I can appreciate the sheer insanity of it, as well as the engineering behind that little gem of a screaming V8. The thing is that, even for the track, how many non pro drivers can handle 1000 hp/ton? I know that it would be wasted on me. It's far more than I could use in a safe or fun way, and I wonder how many people who say they'd want it can see beyond the number on a page. Again, I'd love to have another 100 hp in my car. It'd be more power than it would need, but oh so much fun. But 1000 hp/ton??? I just don't ever see myself saying that what my MX5 needs is another 935 hp.

Miguel

[havoc]

Miguel said:

I just don't ever see myself saying that what my MX5 needs is another 935 hp.

Wuss!!!

More seriously, that's just conjured up a very weird image...a 1000bhp MX5 dusting bikes in a straight line!


I think the general consensus is that all the current crop of 'extreme' cars are probably a little too bonkers for sensible consideration...but boy are we glad that someone decided they needed to be made!!!

[jon b16]

RobM77 said:

jon b16 said:

RobM77 said:

jon b16 said:

Here's a couple of vids of me in the 300...

straight line performance.... 0 to 90mph in 5.3secs - this vid is from 0-80mph (on private road of course )
http://www.youtube.com/watch?v=RoLhzTFoS10

First time in the atom on track - you can hardly criticise the handling can you?
http://www.youtube.com/watch?v=V2uvtSsZ7DI

Those are some great videos there. Very smooth driving - in fact so much so it's hard to tell how close you were to the limit How close were you to the limit, and how to they handle if you're going for a quick lap?

Cheers - 1st time in the car on circuit so i reckon there was a fair bit left in the car - especially under braking

I'd agree, yes; quite a bit left under braking, but also in most of the corners. Have you had a chance to push it yet on track and see what it's like at the limit?

you must really know your stuff

[Miguel]

havoc said:

Miguel said:

I just don't ever see myself saying that what my MX5 needs is another 935 hp.

Wuss!!!

More seriously, that's just conjured up a very weird image...a 1000bhp MX5 dusting bikes in a straight line!


I think the general consensus is that all the current crop of 'extreme' cars are probably a little too bonkers for sensible consideration...but boy are we glad that someone decided they needed to be made!!!

Wuss.

Yes, I'm glad, too.

Miguel