Race and Vehicle Simulations

It’s the smells I miss.  The crisp scent of an early morning track walk, the alluring aroma of bacon wafting in the air as the trackside van gets itself started for the day.  And then, when the first motors fire up, the sweet, acrid miasma of two-stroke oil starts to fill the air; a distinctive smell that always gets me in a wistful mood.

These Sunday mornings were part of my routine for many years; first in my teenage years, and then more recently as I indulged in the Club100 national championship for those of a slightly more adult age.  Once the smell had set in, and any additional weight saving garnered via a troublesome visit to the lavatory (fireproof overalls not recommended), heading out onto track for the first practice session remains, to me, the best way to “blow out the cobwebs” of a morning fug.  Two-stroke 125cc karts are simply joyous to drive, direct drive and no drivetrain lag, relatively light-weight, and with the right cogs the motor will sing all the way to 15,000 rpm.  Chugging at lower revs, the driver must develop a technique of feathering the top end of the throttle to avoid flooding the engine before the power band arrives and the kick in the back with it.  Once the engine is on-song, the corners arrive quickly, and the grip level on fresh tyres can be immense. As you crank it from turn to turn, an almost zen-like state takes precedence, and there can be no better meditation.

That is, of course, unless you’re new to it, in which case you can jump into the thing and wonder why you bothered!  Everything is violent, the brakes are snatchy and don’t seem to work when they are cold, if you give it too much throttle at lower revs in a corner it bogs down horrendously and other karts fly past you like you’re standing still, if you take the brakes too deep into a corner it can spin on a sixpence, and you can’t work out why it’s understeer one second, and oversteer the next.

Plenty of times I would see the first-timers in Friday practice, wrestling around, frustrated and angry at the wilful beast beneath them. Many, of course, had run the traditional “let’s do karting” session, with work-mates or friends, down at some indoor hangar where the lawnmower roar of twin-engined four strokers filled the air. Heavy at the rear, light at the front, a centrifugal clutch and the throttle response of a Transit van (if you’re lucky). It was easy to beat Gladys from accounts. Those old lumps pull 40mph at best (usually exaggerated by the overly self-important race steward in the briefing), and respond only to hustling and throwing around.  Winning in these events can make one feel special, and make one think of stepping up to another level.  Then, one Friday, one ends up in a 125cc kart that clocks 60mph in 4.5 seconds and pulls 3-4 G in the turns.  It’s another world.

And it’s a world that has never been convincingly built into a racing sim,  hence why I was rather intrigued to see what ISI made of it with their recent release of exactly the vehicle I have raced more of than any other for their eternal beta of rFactor 2.  With their “Kart F1” vehicle I was able to try something similar to the Birel N35 I knew so well, and with a fixed weight of 158Kg (driver included) I didn’t have to live on lettuce leaves for a week before the race.

My first concern with karts in a simulator is that of the driver feel and balance in the chassis, something that comes very much down to the inner ear.  As with a motorcycle, the movements the driver makes in a kart can affect the balance and handling in itself, the driver is, after all, the heaviest “component” of the vehicle. However, this can be overblown, as it tends to be the case that one may lean a little on a given “cheek” to push a little extra grip to the outside tyres in some turns, but there is no real clambering around to be done.  Karts, of course, have no suspension, at least in a “springs, dampers and roll bars” sense, so the movement in the chassis comes from hubs, and steering mounts, as well as the flex of the tubular metal frame.  As with any four wheeled vehicle, the balance of the chassis on corner entry is crucial, optimally marrying longitudinal grip with the lateral load on turn in is the difference between a clean entry and a messy one.  In the remarkably stiff and unrelenting chassis of a kart, this becomes very clear with more and more laps in real life, as what seem like small errors can amount to a lot of laptime lost.

Whilst a simulator can give you a very good idea of front end lateral grip via the force feedback, understanding the front to rear weight transfer is not as intuitive. When in a kart, you may be working with very short braking areas with a critical turn in point that, if missed, can make for a very different corner and a lot of time lost.  If you brake too deep you risk overloading the front tyres with the amount of weight that is pushed forward or, worse still, unloading the rear so much that the rear axle locks and sends you into the hedge.  Concurrently, if you release the brakes too soon there may not be enough weight over the nose to generate the grip needed for a perfect turn-in, leaving the front tyres scrubbing as the driver increases the slip-angle, and an apex missed.

Seat time in a real two-stroke kart will give a skilled driver a feeling for this delicate balance that allows them to become as smooth as they can be, for it does not take long in these vehicles to realise that smoothness is key and that, as Carroll Smith once said: a sliding tyre is a slow tyre. Once a driver’s perception of this front to rear balance is established, they can start to work out where they may wish to use more yaw on entry, or where they want to keep the kart more planted.  For many it is an almost subconscious relationship, as the man (or woman) and machine meld more than in any other four wheeled vehicle.

Of course, a similar relationship exists in all car racing, but in a kart those balance decisions have to happen far quicker, as the lack of any suspension makes the driver’s feeling the most crucial aspect of the grip balance. This does not come from the steering force, or visual cues, but rather from a combination of the inner-ear and “seat of the pants”.  So how can a simulator hope to relate this feeling using on screen visual cues and, erm, steering force?

Let’s take a look shall we, by taking to the track in the 125cc “grown-ups” kart (the other option is the Junior kart, with a smaller chassis and less beans; it’s what you see 8 year olds driving down at the local kart track!).  ISI have built a track named “Quebec” (bearing a remarkable resemblance to this place) that comes in four configurations of varying length. To get to know the kart, I opted for the “medium” configuration which features a combination of different corners that should give a good idea of the overall handling.

Now, the first rule of thumb with every sim, and every car within a sim, is that it is important to get your driving right before starting to obsess about setup.  The sure fire way to go the wrong way on setup is to have failed to get yourself completely comfortable driving the car before you start to change things.  Once you have settled down to a consistent laptime that you can replicate every time out, then start looking at how to improve the car (or kart in this case).

One of rFactor 2’s biggest enemies as a piece of simulation software is also one of its biggest assets, that being it’s open and customisable nature.  Setting up your own controllers for the optimum feel can take some time, and anyone new to the sim could find it a bit of a minefield.  The fact is that once you have it set, you should not have to play with it again.  One change I would recommend, however, for everyone with a high end wheel, is to ensure to set up the “Steering Torque Minimum” setting in the controller.ini (more information on FFB settings and feel can be found here

If we assume that we all have a good feeling on the wheel, the first thing to notice with the Kart is how stiff the steering is. The steering ratio is very low, meaning that a very small movement will give a lot of “turny”, this technical term is important to note, because if you’ve spent the last few months driving some other sim car the natural response is to be doing far too much turny everywhere for a few laps.  Once you get used to it you should find yourself feeling the force from the tyres more and thus using ever more delicate steering inputs. With a high-enough-end wheel you may find that you’ll need to open a window too, as it can be hard work!

Whilst, personally, immediately at home when it came to steering input, I was having some problems with the brakes. My natural feeling from real-world experience is to use a relatively heavy foot on the brakes in one of these karts, usually with an initial “thrapp” on the pedal that once applied I ease down as temperature builds in the brake pad.  Being delicate with a single disc rear (I was never rich/fortunate enough to enjoy a kart with front brakes) would have it achieve just about nothing, but a good firm kick gets it working and, with enough seat time, achieving ample braking performance with no lock-ups.

Of course, no one wants a locked rear axle, and I do not have a pressure based brake pedal on my sim rig, so my natural feeling to hit the pedal hard is not helping matters.  This is especially true on the big stop into turn four, so I start to modify my driving to a more “sim-like” touch on the brake pedal.  rF2 models the throttle reasonably accurately, however, although the kart never seems to stall when stopped (Presuming that it is a direct drive machine which it may not be), it does bog down notably in lower rev ranges, and a gentle foot to tickle the motor into its power band is required.  Once up there, the throttle is nicely responsive but you sometimes feel that there should be a little less longitudinal grip coming from the axle, as when exiting under power you rarely feel too much by way of yaw at the rear helping the kart out of the turn.  This could be down to setup though. Hmm, may soon be time to have a look at that.

One of the tenets of driving a kart optimally is that we’re told that we should always either be on the brakes or the throttle, and never coasting.  Now, I will be the first to admit that I raced against many people who were much better at this than I am, but it is always something in my mind when I am thinking about how to improve my lines in a corner or where I could be losing speed.  The fact is, that when coasting you can lose half a tenth in every corner; if the space in between being off the brakes and into the throttle is delayed, then that delay costs time.  The default setup, I am finding, is far more aggressive than what I am used to. The kart is too sharp on entry, with notable camber thrust and front end instability under brakes, and this is meaning that I cannot brake as deep as I may wish, or feel confident with the throttle early on; chances are this setup was designed by someone who is a very quick kart driver. I think it’s time to take a look…

You may think that setup in a kart should be a relatively straightforward affair, but in reality it is just as much of a compromise as in a full sized car.  Another area where rF2 lags behind some of its rivals is that setup is not calculated within the engine there and then, thus, where you would find, for example, that changes to ride heights may affect static toe and camber, there is no real time reading from the vehicle “resting” in the setup screens.  This essentially makes for a bit more hard work, as it is inevitable in a kart that, without anything to “soak it up”, the alignment of the front wheels will change with any changes to weight distribution or ride height.  The good news is, however, that any changes you make on these areas are changes you are likely to stick with from track to track, though it is conceivable, given the complexity of the rFactor 2 simulation, that changes to track conditions could result in you searching for a different balance.

When it comes to weight distribution, this setting is usually not something to work with too much. In a real kart there has to be a reasonable amount of concentration on seat placement, as this obviously affects weight distribution considerably, as does the drivers posture in the seat.  In the simulator, we will have to assume that our driver has impeccable posture, and that his hands are in the right position on the wheel.  The default setup presents a weight balance front to rear of 42%/58%, which is reasonable enough. I tended to run more like 43.5% front end, but with a different chassis so the numbers probably would not tie up (not to mention different tyres).  Changes to this setting can adapt the way the front end behaves considerably, as more rear bias gives much more push in the corners, whilst naturally the opposite happens with the weight further forward.  For now, whilst my focus is on making the front end a little less reactive, I am going to leave the weight balance as it is, and look at alignment.

The default setup had the negative camber set a bit too high for my liking at the front, so I dropped that a few clicks, and made the front toe neutral, something I’ve always done for reasons that my memory cannot recall from the distant past. I remember once being told how negative toe at the front end may give dividends on turn in, but it creates drag on the straights as the fronts push against one another.  Where the benefit truly is I’ve never been sure, but I do prefer the steering feel and turn in balance with neutral toe, so that’s what I am doing.  And screw it, I am dropping the tyre pressures a bit too, a bit more than that bit at the front.  The anti-roll bar, as it is termed in the GUI, is a torsion bar that sits in the front grill; wide and flat in appearance, it gives more stiffness mounted vertically than horizontally, usually meaning a tighter and grippier front end when vertical (in case you were wondering). I’m leaving it horizontal.  Time to head back out.

Much better.  Now I can feel the front end more precisely, and can thus play with the mid corner balance a little.  Whilst I still have a relatively sharp turn-in, there is a touch of mid-corner understeer that serves to stabilise things, especially when arriving into the corner a bit too hot.  With more and more laps the kart comes to me and with it the lap times. For areas in real life driving where I may “feel”, in the sim it takes time to adapt to the balance; the feeling comes, but it takes time.  Laps are frenetic and apexes arrive very quickly, flicking from turn to turn, but with every lap I get smoother, feeling the front to rear balance on entry, it may not be seat of the pants but it’s certainly a lot of fun, and before long I am able to “twist” the kart into the corner with minimal steering input, inspiring the kart into the corner on the brakes.

More seat time allows me to slow things down in my head, growing ever more used to the limited steering movement and the tight envelope of performance in the tyres.  Delve into too steep a slip angle and the tyres catch too much lateral grip and things start to get out of shape, shedding tenths in every corner. But get it just right, and the as the rear comes around on entry you get back on the throttle and smoothly carry speed though the turn.  Since build 494, rFactor 2 has calculated the force feedback directly from the modelled steering column force; it makes a notable difference and really allows the driver a much more tactile feel in the steering. At the same time, the throttle sensitivity is dependent on available engine torque, making smoothness ever more important.  It’s no use just banging the throttle down on the exit of corners, as at lower revs the motor will bog down, so when getting back on the throttle mid-turn one has to take into account the current rev range that the engine is in, slowly applying more throttle as the revs rise; it’s tricky, but still much easier than it is when you’re trying to do it in a real kart, where your feet are being bounced around constantly by the various G forces and bumps.

Modern racing simulators are very complex, and model vehicle controls in such detail, that I find it imperative to put in the time to learn a car.  Anyone that thinks they should be able to just jump in anything and be fast and clean and perfect the first lap out is deluding themselves.  Even the most talented driver has to put in time to come to terms with the delicate balance of each and every race car without the inner ear and “through your arse” feeling that, in real life, allows one to adapt so much more swiftly to a vehicle.  This is exacerbated in a kart, where the tolerances are so low, and the speed penalty for getting out of shape so high.

It’s time to race the AI. rFactor 2 has, I believe, some of the best AI available today; it really allows you to feel like you are racing against different personalities, and they can be real trouble to deal with at times.  Having run practice for an hour with 22 AI at 100% and aggression at 75% I decide, after setting the fastest time by five tenths, that I will start from 18^th place and see how everyone gets on in a thirty lap race. By lap ten I am sweating, and still only in seventeenth place; I’d managed to climb higher but then an over ambitious move on an AI chap, that I had rashly assumed would be much nicer to me, had me pushed onto the grass and I lost three positions.  Running in the middle of the pack in kart races like this is frenzied, and almost feral.  You can easily end up lapping three seconds slower than you could manage on your own, as the defensive position of the kart in front of you slows you up, in turn allowing the inevitable pack of karts behind you to close up and start snapping at your heels.  Finding a way past can be a real struggle, and an attempt to make up one place can go wrong and see you losing three.  One thing is for sure: if there is one place to develop racecraft, this is it.

Once I find a gap I am able to put in two fast laps and rapidly close the gap to the four karts battling ahead of me. The back two are side by side as I arrive upon them, slowing me down through the final complex of corners as they slip through the chicane side by side.  I drop back a little, take a clean run through the final turn and pass them both, dispatched.  That’s it Denton old son, strike while the iron’s hot, and all the other clichés you can think of.  By the exit of turn five I am up on the next victim, kart number six.  He’s slow through the long radius of turn six, so I try to line him up into seven but the door is closed, he baulks me through the turn and I lose speed by avoiding a rear-end bump. I glance back; those two are still dicing with each other and there’s a bit of a gap. Okay, breathe.  I’m fairly sure number six just brake tested me into the chicane, but maybe he just likes to brake early.  Either way, he screws up my run and I get a bit sideways on entry to the final corner. Chasing him down the start finish straight, I whip through turn one and I am right on him, he covers the inside into two and I dart to the outside. I should have him here, the bastard. But hang on, he’s compromising his own apex to push me wider; he’s hanging me out to dry, ARG!  I drop back in behind him and a glance back realises that the lads behind me are now right on my tail. DAMN YOU NUMBER SIX!

WOAH! I am sure he could have braked later than that, he’s trying to destroy my mind. By once again being caught out by his early brake test I am compromised on the exit and the red kart behind me ducks up the inside coming out of the hairpin at turn four. I’m having none of it; I hold the outside through five but he hangs on into turn six, where the green rear bumper of kart six is filling up the inside, red is coming around me and I have nowhere to go! I have to yield to red into turn seven, then he is alongside green number six as they approach the chicane.  Six pushes red up onto the kerb and he slows, I pass him, then end up on that damn green bumper again through the final turn.  By now the next kart is a few seconds up the road, I have no idea what position I am in, but I doubt it is within the top ten.  It’s not fair! I am the fastest kart on the track in clear air but these guys are, well, far too realistic.

I eventually pass kart six; he takes his now standard defensive line into the long right hander at turn six, I dive to the outside and carry the speed though, then block pass into turn seven. This time he’s the one with nowhere to go.  I pull away by a second a lap on the swine, and eventually finish the forty minute race in thirteenth place, sweat dripping from my brow.

I am working on Eliot to get a server setup for some racing online, which hopefully should be just as much fun once everyone is used to the vehicles.  The splendidness of rFactor 2’s racing environments cannot really be doubted; the sim gets a harsh press due to its graphical style but, for me, when you are in the cockpit it looks superb.  The lighting and shadows are perfect, the “real-road” technology has been refined and gives a great feel for the changes in a track over a race weekend, the weather can be adapted in any direction you please (I ran another 30 lap race in Quebec that was interspersed with two rain showers, the track becoming moist, then a dry line emerging throughout), and racing the AI can be truly rewarding.  It’s only a shame that the karts don’t come with the “visor mod” that can make the view from the various single seaters in this sim so pleasing.  Regardless, this is the best example of two stroke karts I have tried in a simulator. There  are aspects of reality that it cannot replicate, and it will  never be quite the same as being out there on track for real, but one thing is for sure: it’s a lot of fun, and a lot less bruising to the ribs.

There’s nothing better for blowing out the cobwebs.