Braking and turning in - Trail Braking

[Reca]

FWIW:



Speed is as per usual from engine noise, longitudinal acceleration from speed (needed bit of filtering to get a smooth graph), while lateral acceleration is obviously speed squared divided cornering radius.
The radius comes from a plausible racing line, computed to minimize a fitness function of various parameters (lat acc, distance travelled, radius etc) in between boundary limits of track from satellite image.

Needless to say that it's all subjected to error (not quantifiable till RBR sends me real data… not holding my breath...) so certainly we can't take that as an accurate measure of RB7 performance limits, but for the scope of this thread, to be used as qualitative reference to get an idea of how a similar plot looks like and how speed (thus downforce) influences available grip for a F1 car in general, it should be good enough.

[raymondu999]

Wow. That looks more like a job for a 3d graph rather than 2d.

Back on trail braking though - surely trail braking should only be done as the driver is still turning the steering wheel? If and when the driver has held the angle steady; surely the driver is better off using all the grip for lateral acceleration and carrying speed across?

Okay Trail braking can give you a deeper braking point. But if you brake earlier in a straight line; you could probably brake harder; and carry more speed across. Surely there would be corners where it's more beneficial to do a more "conventional" driving arrangement?

[timbo]

Surely there would be corners where it's more beneficial to do a more "conventional" driving arrangement?

I can only speak from my simracing experience, but yeah, definitely.

[raymondu999]

Actually I've been looking at some F1 on boards; and it surprises me that in qualifying; not many drivers opt to carry more speed onto the straight. Most still trail brake at the last corner (if they choose a more conventional line) or if they go very deep into the last corner and go for a very late apex exit.

[ESPImperium]

At least we know where Turn 8 is on the graph. Thats the bit i can refrence.

[timbo]

Actually I've been looking at some F1 on boards; and it surprises me that in qualifying; not many drivers opt to carry more speed onto the straight. Most still trail brake at the last corner (if they choose a more conventional line) or if they go very deep into the last corner and go for a very late apex exit.

Well, for once at Nurburgring this year both Alonso and Massa chose very wide entry/late apex.
One important thing might be is that it is much more important to maintain a good rhythm and not busy yourself too much choosing a different line to start a new lap. But that also depends on track; some might be not as beneficial than others.
For example, at Magny-Course drivers often chose more gentle line through the final chicane when they started a lap to have a good exit onto the straight, but jumped the kerbs much harder at the end of the lap.

[Jersey Tom]

Okay Trail braking can give you a deeper braking point. But if you brake earlier in a straight line; you could probably brake harder; and carry more speed across.

How do you figure?

[raymondu999]

You could brake harder as you're using all the grip for braking then, and you could use it all for lateral, in the lateral scenario. Hypotheticaly of course, asthose would require step changes in steering/throttle inputs

[Jersey Tom]

Even when trail braking, with few exceptions you still do your max braking in a straight line before you have to start turning in (and releasing brake).

[timbo]

You could brake harder as you're using all the grip for braking then, and you could use it all for lateral, in the lateral scenario. Hypotheticaly of course, asthose would require step changes in steering/throttle inputs

But actually your total possible combined grip is higher than just a sum of lateral + longitudal, so despite you can probably reach higher peak acceleration doing just braking or just turning, your integral acceleration over the curve may be higher if you combine them optimally.

[Giblet]

Does trail braking also involve a little more brake balance to the rear? My understanding (which is often wrong) is that you start to find the grip and get the front turned while the rear is still braking a bit harder, sort of 'skidding' into the corner starting the car rotating?

I've never fully understood trail braking but I'd like to. Its very popular in sim racing. Is it due to tire wear not being as much of an issue?

[timbo]

Does trail braking also involve a little more brake balance to the rear?

Yep. The more rearward is your brake bias the less understeer you have while trail braking.

[Jersey Tom]

I've never fully understood trail braking but I'd like to. Its very popular in sim racing. Is it due to tire wear not being as much of an issue?

It's popular in sim and real racing because it's the quickest way around the track.

You get to carry the same amount of mid corner speed, same exit speed, and you get to brake later. Can't beat it.

[raymondu999]

The way I've kind of got my head around this is that on the traction circle; starting on the 0 degree point on the traction circle; then moving along the edge until you're 90-left or 90-right from the circle. i.e. basically an "on-the-limit" transition from 100% braking to 100% turning on the traction circle.

JT - on a side note; with the Pirelli's alleged situation; where several people say that the rears are very easily saturated if you put them under compound lat/long loads; how much would it affect trail braking? I would suspect that it wouldn't have as big an effect as if the fronts were the ones that had that problem, no?

[Jersey Tom]

Yeah it's something I've heard in various instances before... tire sets that "only let you do one thing at a time" or in other words don't work great in combined mode. Conceivably there could be a few reasons for it though.

Good example of not taking drivers' comments at face value.