I was spectating at a GRC event on the weekend and I saw something odd in a video clip on the big screen with a driver commenting on a lap around the track. He said that the fastest way around one corner, a 90deg turn right in the middle of a long paved section (so there's no dirt on the corner) going onto a long straight, was to use the handbrake to throw the car sideways, "to get good power out of the corner" I think were his exact words. Going sideways to go faster on pavement seems completely wrong, but all of the drivers did come through that corner at least a little sideways so there must be some merit to it. How can this be?
My best guess is that sliding at full-throttle results in better acceleration out of the corner than gripping at part-throttle due to turbo lag. He said specifically that he uses the handbrake so it can't be that the car has such ridiculous oversteer that trying to grip the corner is pointless (I drove a rally car like that once and there was no need for any handbrake).
It's about getting the car rotated so you can mash the gas and go where you're pointed. GRC happens very quick, there's often not a lot of time to set up with regular braking, or so I'm told. On a quick corner they're never off the gas, just handbrake to rotate and go.
Bear in mind that "grip" and "sliding" are not separate things. At maximum grip you are sliding a certain percentage, and when you are sliding you are still generating grip.
Also bear in mind, the earlier you can accelerate out of a corner, the more speed you will have at every point afterward, So if pitching it sideways and powering out allows higher exit speed, then go for it!
Search for and learn about 'friction circles'.
Knurled wrote:
Also bear in mind, the earlier you can accelerate out of a corner, the more speed you will have at every point afterward, So if pitching it sideways and powering out allows higher exit speed, then go for it!
Yes. Even if you actual time through the corner is slower. If your final speed at exit is higher, and you can multiply that difference by a very long straight...
Which driver and which corner? I can add some insight to it. I was at the event.
In general, some of them drive old school and practice defensive lines even though they may not be faster for the time trialing section.
I assume Barbados, and the back straight in front of paddocks, the corner is go kart width, and only really room for one car. It was better to rotate into a better setup coming out of that corner for the long middle straight, but only marginally and car/gear dependent. Too wide or too deep and you lost any gain and then some.
I didn't see the broadcast yet, but I'm fairly certain I know which driver it was, as many in the paddock thought it was a very "interesting" line. I would call it offensively defensive. 
In general, the line chosen by the different drivers in the series varies greatly. The neat and tidy lines are proving to be better(shocker), but the drifting is still necessary in defensive situations.
I know about the friction circle but I don't see how that answers the question. When tires are sliding (more than the miniscule ~10% wheelspin/5-10deg tire slip angle to optimal grip) they're outside the circle and generating sub-optimal grip for pavement, so it seems that either the tires in use have some unusual properties or that grip is actually being sacrificed for something else (like turbo spool-up).
sachilles wrote:
Which driver and which corner? I can add some insight to it. I was at the event.
I tried to PM you to see if you'd be there, you didn't answer!
Anyway I wasn't talking about any driver in particular, some did use more slip angle than others but all used some, even in heat (qualifying) races and in other situations where there was no need for defense, and I thought it was an odd technique. I was talking about the corner going onto the top straight near the grandstands though.
I didn't have a great view of the corners near the paddocks, in fact I could only see the one between the bottom straight and the middle straight through the big screen.
PM not received. Sorry.
I couldn't see that corner you were referencing from my vantage point.
I think it was likely power on rotation. The joker intersection was the corner before, and that was causing fits for many, to the point they painted a lane there for Sunday.
Some of what goes on is that a few drivers like to bump from behind, and it's easier to be somewhat sideways and recover. If you are bumped during a "tidy" line it is more likely to understeer and send you flying.
Long story short, its pretty easy to see which drivers have a history of road course driving, and which come from a more slip related racing discipline.
Had too many comp tickets for the event, wish I remembered you were going, I would have made sure to get you a couple. Where did you stay? We were at the Accra resort which was quite nice.
Uhh I stayed at home 
Accra's not far from my office.
Also the driver comment was probably a go pro preview, and it was likely Dyne. I guess I would say he tends to take a non-traditional line.
rcutclif wrote:
1. All cars have some slip angle when cornering, maybe rally tires have larger optimal slip angles on pavement than dedicated road tires.
Rally tires are almost like bias-plies in the way their traction circle is. They're built more for toughness and "forgiveness" than maximum traction.
Of course, I doubt these guys are running on rally tires. Rallycross-specific tires do exist, they are like runflat slicks with rubber made out of a cross between an eraser and a sponge. You can stick your finger into them.
WRC rally drivers drift on tarmac stages. Sometimes it is the fastest way around particularly tight low speed corners.especially in an AWD car.
GameboyRMH wrote:
Anyway I wasn't talking about any driver in particular, some did use more slip angle than others but all used *some,* even in heat (qualifying) races and in other situations where there was no need for defense, and I thought it was an odd technique. I was talking about the corner going onto the top straight near the grandstands though.
I wonder what kind of diffs they use. Driving an AWD car with open or loose limited slip diffs is a point-and-shoot kind of thing, but if you have something like my Quantum where the differentials are locked, the only way to get the thing to turn is when off power. On power the car is going in whatever direction the nose is pointed, so you kind of have to chuck it in and power out or else you're not going anywhere since turning in more means lifting and lifting is losing.
Again I dunno what kind of diffs THEY run, if they run clutch pack diffs, or if they have viscous LSDs, or if they just have an axle disconnect for handbrake like the recent WRC spec is.
midniteson wrote:
WRC rally drivers drift on tarmac stages.
No, they don't...
Sliding is NOT drifting and vice versa.
Knurled wrote:
midniteson wrote:
WRC rally drivers drift on tarmac stages.
No, they don't...
Sliding is NOT drifting and vice versa.
Oh ok thanks for clearing that up. WRC drivers "slide" on tarmac stages....
In addition to the points about getting it rotated and back on the gas, and the particular case of a tight corner which isn't going to allow a lot of momentum anyway, I wonder whether the soft setup for the mixed terrain reduces the advantage of a "road course" cornering style; if it's going to roll a bunch, that's going to limit peak grip considerably, right?
Not sure it's a significant contributor, but another thing to ponder.
Rally/ rally cross cars have a separate rear hand brake in addition to the regular four wheel foot brake. not the usual parking brake aka emergency brake
FYI, locked center diff per rules with 50% front rear bias. We use Radial yokohama slicks.
Got to watch most of the Barbados rounds telecast last night courtesy of the DVR. The corner in question, it was definitely power on over steer, and pretty moderate at that.
Ransom wrote:
In addition to the points about getting it rotated and back on the gas, and the particular case of a tight corner which isn't going to allow a lot of momentum anyway, I wonder whether the soft setup for the mixed terrain reduces the advantage of a "road course" cornering style; if it's going to roll a bunch, that's going to limit peak grip considerably, right?
Not sure it's a significant contributor, but another thing to ponder.
Wide variety of firmness based on driver preference. One of our drivers prefers more roll than the other. Tire temps suggest either is viable, provided everything else is setup properly. The jumps and just how loose and rutty the loose surface is at the venue is a factor in the choice.
My last comment for now is that the universal truth of....the driver that moves the steering wheel the least, will likely be the most efficient.
Also note on the Barbados round, there was a fair amount of ditch hooking on the inside curbing.
The TR8s I drove on track had a ridiculously short wheelbase of 85 inches. Sideways in corners you entered under heavy breaking was the fastest way around the track. None of that slow down to go faster technique worked with these cars. Made me a great driver in the rain, because I was used to the car sliding all over the place.
