Top Speed

Apex · Post 03 Sep 2005, 17:50

It should be remembered that the mass of the car does have an influence on the top speed in a sense that it will reduce the acceleration. If you have a limited run up distance, then weight is very important.

Dont believe me? write a m file and see just how drastic a difference it makes.

DaveKillens · Post 03 Sep 2005, 19:08

So with the "Bonneville 400" logo on the side of their cars, that is now the goal.
400 kph = 248.548477 mph
To me, that appears a realistic and safe goal. It would be terribly embarrassing to publicly proclaim a goal and fall short.
I expect 400 KPH to be met, and probably exceeded.
So, how will this car deviate from the normal practice?
The wheels have a minumum width of 305/365 mm front/rear. brake ducts have no minimum size, so expect them to disappear. The tires will probably be an ultra hard compound, and inflated to a very high pressure. Additionally, camber may be radical to reduce rolling resistance. The only goals of the suspension is to deliver stability and reduced aero and rolling resistance. Sidepods will probably be drastically decreased in cross sectional area, and the bargeboards will probably be designed more to channel air away from the high drag radiator intakes. All extra protuberances will be cleaned up and or removed. Panels will be closed and taped to reduce turbulence. In fact, it may be worth the effort to produce large, one piece body panels. Impracical in a race weekend, but maybe worth using for high speed. In fact, they don't even need to be made from high tech carbon fiber, ordinary fiberglass may be substituted, since ballast and weight are not critical to performance. For instance, the fuel filler doors could be eliminated and to refuel, the panel would have to be removed. Like I said, totally impractical in a race, but worth the effort on a top speed scenario.
I'd like to see other input, since developing a car that meets FIA specs can be quite different than a car optimized for a GP weekend.

manchild · Post 03 Sep 2005, 19:54

What about the gearbox and diff?

If they make special gearbox diff. ratios for this attempt than 400 will be a joke. What if they make car with awful acceleration compared to some F1 circuit tailored gearbox?

BTW, Pedro made over 369 in Monza with racing setup that includes care about downforce and need for good acceleration and elasticity. Why would than additional 30 km/h be difficult to reach?

Guest · Post 03 Sep 2005, 23:26

just to remember : in 1986, during the turbo era, with the highest power in the history of F1 cars, about 1300 bhp in Monza for qualifications with BMW Benetton and Berger, its maxi speed on the straight was "only" 351 Km/h.

RH1300S · Post 04 Sep 2005, 00:00

Anonymous wrote:just to remember : in 1986, during the turbo era, with the highest power in the history of F1 cars, about 1300 bhp in Monza for qualifications with BMW Benetton and Berger, its maxi speed on the straight was "only" 351 Km/h.

Yup, but they were dragging barn doors behind them

DaveKillens · Post 04 Sep 2005, 14:07

manchild wrote:BTW, Pedro made over 369 in Monza with racing setup that includes care about downforce and need for good acceleration and elasticity. Why would than additional 30 km/h be difficult to reach?

For aero drag, the square root rule applies, double the speed, you square the drag. Because of this, it's the last few MPH in top speed are the hardest part.
Who know what the gearbox will be. It may even have a few clusters removed, to reduce drag. I would not be surprised to see just four gears, if they can achieve acceptable acceleration with that.
If we accept the premise that BAR will run a car not very changed from the usual race setup, then theres really not much point in this exercise, because the cars pretty much top out in speed at certain tracks with long straights. So, IMO the car will be modified, but still be FIA legal. It would be a dog in a race, but that's not the point, top speed, and only that is the goal. In essence, it won't be a Formula One car, but a land speed record car, optimized as much as possible to get the most MPH. The purist in me recoils, and I don't consider this as a true road race car, just a modified race car that goes fast, but sucks as a road racer.

mramosmonteiro · Post 05 Sep 2005, 02:33

to reach the top speed, you need to accelerate...
to accelerate a larger mass you need more power.....

mramosmonteiro · Post 05 Sep 2005, 02:37

[quote="Apex"]It should be remembered that the mass of the car does have an influence on the top speed in a sense that it will reduce the acceleration. If you have a limited run up distance, then weight is very important.

Dont believe me? write a m file and see just how drastic a difference it makes.[/quot

to reach the top speed, you need to accelerate...
to accelerate a larger mass you need more power..... e]

Guest · Post 05 Sep 2005, 11:47

No you dont!.

You only need more power if you want the same amount of acceleration with a larger mass. Otherwise you only need a longer straight to run at.

/ Fx

Spencifer_Murphy · Post 05 Sep 2005, 12:05

and long enuff gear ratios

DaveKillens · Post 05 Sep 2005, 15:06

I don't have the specific numbers on hand, but for the course at Bonneville, they allow a lot of room. I believe it is a ten mile course, with six miles allowed for acceleration, one timed mile, and about three miles to stop.
So for this scenario, gearing and acceleration aren't really that critical.

RH1300S · Post 05 Sep 2005, 16:01

This accleration/mass/top speed lark...........

Is it not the case that until you reach terminal velocity then the car will continue to accelerate almost regardless of mass. The thing that the mass changes is the rate of acceleration (as said above). Top speed is mainly determined by drag/horsepower (& I suppose having enough traction to connect that horsepower to the road).

I am sure you could do calculations that would show that increased mass would reduce top speed (more rolling resistance?), but in the big picture I don't think it has a major effect.

Of course on a race car it is critical as you want to reach your Vmax in the shortest time possible between corners.

RH1300S · Post 05 Sep 2005, 16:42

I have read that BAR estimate that 425kph should be possible, limited mainly by drag from the tyres.

They are NOT saying the expect to reach this speed, only that this is what they think is the theoretical maximum.

My guess (wild

), using this piece of info is that they will get to somewhere approaching 415kph (let's hope their simulators are good!).