David Turnbull
PrestoGP Veteran
you mean to tell me that the guy in front is NOT! my brake?
a total revise of my driving is needed me thinks :biggrin:
a total revise of my driving is needed me thinks :biggrin:
Nice calculations and those are real. I can only add that in practice the car behind usually has:
1 more speed due to split streaming
2 less down force due to split streaming (hence worse braking ability and traction)
3 worse visibility as most likely the braking point is obstructed by the car ahead
So in (virtual) reality 8 to 9 meters away seems for me like the last point for braking and still a lot of risk that in case of wheel lock/ car ahead too hard brake will result in a collision.
Its much safer to make an early brake - but very light short braking impulse about 20-30 meters ahead of the normal braking point and then hit the brakes hard at or slightly delayed to the normal point. Not only it is safer but also gives a time to react in case of the ahead car makes an error in turn and to adjust your drive line to gain advantage on exit.
OR, Position yourself on the alternate drive line before the brake point. Not only you impose an overtake move on your opponent and pressure him. If you feel confident in the alternative drive line (which with appropriate practice you should) the will be no risk of collision in case either you or your rival, or rides fail during such hard braking periods.
I know such things are obvious for most but after reading the reports not for everybody. Its so sad some players game are ruined when they had expectations and prepared for some time by persons who dont know such safety basics and ram people of the track and just saying "sorry" after wards (not even waiting as they should!). And i also encounter more and more players that learn the track be heart so much they act like a programmed AI, going fast but not reacting to the variables that are encountered on the track - such people are twice dangerous.
I understand that such occurrences can discourage for participation. Sad.
Its much safer to make an early brake - but very light short braking impulse about 20-30 meters ahead of the normal braking point and then hit the brakes hard at or slightly delayed to the normal point. Not only it is safer but also gives a time to react in case of the ahead car makes an error in turn and to adjust your drive line to gain advantage on exit.
When you are following a car at high speed and by 300m out you don't have the line or position to realistically make the pass in a safe and controlled manner, back off and rather that braking as late as possible ease into the braking zone more smoothly. You will not only probably have better control than the guy defending his position but your exit speed will likely be better, setting you up for another attempt.
In such case you cannot blame the competitor (and sometime it happens like "he was slow, he brake too early etc.") the should be also no excuses for self like" i did all i could, braking as hard as possible". That is just rubbish for me and reason that the incident happened proves that individual did NOT do everything that was possible and should have done to avoid it.I have read here that people will excuse themselves to something like "I braked at my usual braking point" at times. You can not blame the competitor. For it does not work to slow down as usual. Therefore, I wanted to start a discussion.
Suppose that two cars are travelling in succession at 320 kmph and slows down to 80 kmph.
We'll find out how much distance is needed between vehicles to avoid a collision.
We measure distance and time between the cars' nose cones.
The cars are 4 meters long.
The distance is 5 meters between the nose cones, and it offers a 1-meter gap between the cars.
The drivers start braking at the exact same time.
This means that the pursuing vehicle's braking point is 5 meters longer away from the apex of the turn.
Speed:
320 kmph = 88.889 meter/second
80 kmph = 22.222 meter/second
Distance and time:
5 meter gap in 320 kmph => 5/88.889 = 0.056 seconds
We assume that both cars were fitted with equally powerful brakes.
Time and distance gap during exactly equal deceleration:
Braking starts at the same point in time
0.056 second gap in 320 kmph => 88.889 meter/second => 0.056 x 88.889 = 4.978 meter
Braking ends at the same point in time
0.056 second gap in 80 kmph => 22.222 meter/second => 0.056 x 22.222 = 1.24 meter
Now the nose cones are very close together (1.24 m), we would have needed more space to avoid a collision.
In this case, the driver who persecute should need to use a braking point about 8 to 9 meters away from the preceding car's braking point.
Its much safer to make an early brake - but very light short braking impulse about 20-30 meters ahead of the normal braking point and then hit the brakes hard at or slightly delayed to the normal point. Not only it is safer but also gives a time to react in case of the ahead car makes an error in turn and to adjust your drive line to gain advantage on exit.
Nice analysis Valter, but there is a few small flaws with your analysis.
1. Braking distance is determined by how much grip your tyres have (at least in real life), not the brakes.
2. your fogetting about the reaction time so that is a few extra meters.
3.Also the retardation rate is different for different velocities. (also we all know that we don't just stamp on the brakes until we slow down to a certain speed, we release the brake a bit so it will not lock up and a bit of throttle for stability)
But this one is hard to work out as ever driver is different.
That is why your 0.056 sec time is a good starting point but not truly accurate when you take more varibles.
4. Also the velocity and downforce difference between cars as metioned above in other posts.
5. Apex velocities differ for different cars (I found this one out specially in interlagos) (sometimes 16 kph difference between me and some other divers when I was running higher downforce.)
So you can see following another driver is not that simple, the safe bet is to brake earlier, and give space to the guy in front.
Great points everyone!
There are indeed many variables that determines the break distance, too many to make exact calculations of. So the simple calculation like Valters is very good to make a point and give a good idea of what you have to deal with.
If you really want to go in depht I suggest comparing two (or more) drivers/situations in MoTeC. Do you have a good (or bad) example of how you act behind another car? A screenshot can show how much you break, speed and maybe forward g-force (retardation).
From some of my data logged from my race I find that it can differ a tenth in the break zone for the chicane just from one lap to another in clean air. This would have consequences if it was two cars close together. Don't have the energy right now to make calculations of it. To tired to think after this week
Nice discussion gentlemen! All I have to add are a few words of many others before me and probably you:
If you are behind someone you should be ready to brake before them unless you are going to attempt to out-brake them, in which case you should not be directly behind them.
It is often difficult to write about but easy to sum up using one word, "patience".
Thanks for all wise words .:thumbup:
.....i think that the people that run yesterday at monza must read this topic really carefully!!!!
T1 was a carnage!!! LOL
That reminds me of some very useful lessons Juha R taught me back in Season One of Presto. Juha would always control the exit of a corner and then positioned his car where I wanted to be on entry to the braking zone for the next one.
Juha and his tales from the Winnebago [F3000]; them were the days:biggrin:.