Paul Jeffrey
Premium
Kunos physics guru @Aristotelis has published another very interesting Assetto Corsa Competizione blog recently, talking in depth about the lovely Lamborghini Huracán GT3 in ACC...
Assetto Corsa Competizione initially released with just one car and one track as it began the journey into Steam Early Access, and over the following months Kunos have continued to methodically work to develop, improve and enhance the title and add yet more new content from the 2018 Blancpain GT Sprint Series championship.
With the shiny attraction of new cars and tracks, one could easily be forgiven for somewhat forgetting the original Lamborghini Huracan GT3 post build release two, and this is something that the main behind much of the physics work at Kunos is keen to remind us all about, posting up a new and as usual very interesting blog post on what was the very first car to appear in Assetto Corsa Competizione...
From the blog post by Aris:
The 2017 champion car, arrives in the 2018 season in an almost identical form. The Huracan GT3, proved in the 2017 season, to be the car to beat in terms of absolute performance. Nevertheless this top level performance was the result of a very professional team with very talented and fast pro drivers that especially on some tracks were able to destroy the competition. The result of this was a very severe Balance of Performance handicap for all the Huracan cars, that heavily penalised the champion team but most importantly all the other teams using the car, further down in the grid and classification.
Objectively the Huracan GT3 is a very capable car, but at the same time it has some very unique and distinct characteristics that often make it difficult to handle for less experienced teams and drivers.
The car is very compact resulting in a very small frontal area and thus very low drag figures. Top speed is almost everywhere amongst the highest achieving cars, often topping the results. The downforce production is also very high, maybe not on par with Ferrari, Audi and Mercedes, but not that far either. The resulting efficiency is top of the class confirming the qualities of the Lamborghini aerodynamic design aided by the famous Dallara engineering. The compactness of the car dimensions, result on a very small under tray area that is quite pitch sensitive. At high speeds the car will become quite unstable under coasting or even worse, braking. As an example the very fast right bend after the long back straight at Paul Ricard has gave me some of the most violent slap tanks in my whole real and simulate driving life. Brake a bit too hard and a bit too late from 280kmh top speed and try to turn in and I can guarantee you, you’re going to change your mind very fast and thank Paul Ricard circuit designers for implementing those very wide runaway areas with blue and red lines that give even higher grip than normal asphalt (at the exchange of massive chunks of tyre tread flying around…). Small amount of ride height change at the front or rear, will move the aero balance quite a bit back and forth. To counteract this, the suspension setup must be adequate to aid the stability under such conditions, with high front stiffness and good damping work in front bump and rear rebound, more similar to a single seater setup, than a more conservative GT racer. The stiff setup will usually make the car jolt and jump around over kerbs and bumps, but surprisingly enough it will stay quite stable if the driver is precise and remains on power.
The mechanical balance of the car is also particular. The road car has an AWD setup that adds weight to the front axis from the axles and differentials. The GT3 car, by rules, has to be RWD and so the elimination of all the AWD mechanical parts, results in a very rear weight bias. As a matter of fact, the Huracan starts with about 60% of its weight at the rear tyres making it practically a very rear heavy car, similar the Porsche 911 that, let me remind you, is rear engined! A car with such weight bias, would need a staggered tyre setup. This means that the rear tyres should be wider than the front, to handle better the different loads.
Unfortunately the tyres offered by the rules, have very similar dimensions for both front and rear which means the mechanical grip is a bit unbalanced with more tyre at the front, than what the car needs.
To the uninitiated, this might sound like a non issue. The car seems to understeer constantly, so more tyre to the front, can only fix the things right? Why does it make it worse then? To have balanced handling characteristics you need to have a predictable rear grip, so that you can shift the weight with your driving inputs and you get back predictable feedback and reactions. If you have more rear grip than front, then you can use the power on the exit of the turns to rotate the car and it will do so gradually, because even if you lose some lateral grip, you still have plenty to handle. But if you have more grip at the front, the moment you get power understeer (and you’ll get it because of the weight bias to the rear), then trying to power oversteer will subtract important amounts of grip from the rear and it will make it skittish and nervous. On top of that, add a quite sensitive aerodynamic platform that we described above, that moves the aero balance heavily to the front and to the rear every time the pitch of the cars changes by mere millimetres and you get a more clear view of why the car requires skills and respect from its driver.
Sounds like a difficult car to handle and it is when you try to push it hard on the limit. Setup must be balanced and on the stiff side, especially at the front. Don’t try to overcome the power understeer with a more oversteer setup, because you’ll end up with a nervous turn in that will make the car slower. Embrace a hint of understeer, be more precise in your inputs and driving line and learn to take advantage of the aero platform and mid turn speed. You can brake late, start to turn in, but get off the brakes as soon as possible and let the car coast to the apex or with a very very slight brake input, anything more and it will understeer at turn in too. Learn to do the coasting part properly and you’ll be surprised by how much speed you can carry inside the turn, which will be translated in time gains outside of the turn. This is taking advantage of the aero platform, leaving the car as flat as possible instead of forcing it to turn by braking and pitching. The results might surprise you.
If properly setup and driven, the Huracan GT3 showcases a very fast turn in and high mid turn speeds. Exceptional traction and agility makes it perfect for slow narrow turns and chicanes. There’s always an understeery behaviour on power at the exit of the turns and generally the car doesn’t like to change its line once in the turn. Precise driving and proper racing techniques are required to make the car deliver, but even thought it might not feel “fun” and requires lots of self control, concentration and commitment, it is capable of blazingly fast laptimes that reward all the hard work.
Objectively the Huracan GT3 is a very capable car, but at the same time it has some very unique and distinct characteristics that often make it difficult to handle for less experienced teams and drivers.
The car is very compact resulting in a very small frontal area and thus very low drag figures. Top speed is almost everywhere amongst the highest achieving cars, often topping the results. The downforce production is also very high, maybe not on par with Ferrari, Audi and Mercedes, but not that far either. The resulting efficiency is top of the class confirming the qualities of the Lamborghini aerodynamic design aided by the famous Dallara engineering. The compactness of the car dimensions, result on a very small under tray area that is quite pitch sensitive. At high speeds the car will become quite unstable under coasting or even worse, braking. As an example the very fast right bend after the long back straight at Paul Ricard has gave me some of the most violent slap tanks in my whole real and simulate driving life. Brake a bit too hard and a bit too late from 280kmh top speed and try to turn in and I can guarantee you, you’re going to change your mind very fast and thank Paul Ricard circuit designers for implementing those very wide runaway areas with blue and red lines that give even higher grip than normal asphalt (at the exchange of massive chunks of tyre tread flying around…). Small amount of ride height change at the front or rear, will move the aero balance quite a bit back and forth. To counteract this, the suspension setup must be adequate to aid the stability under such conditions, with high front stiffness and good damping work in front bump and rear rebound, more similar to a single seater setup, than a more conservative GT racer. The stiff setup will usually make the car jolt and jump around over kerbs and bumps, but surprisingly enough it will stay quite stable if the driver is precise and remains on power.
The mechanical balance of the car is also particular. The road car has an AWD setup that adds weight to the front axis from the axles and differentials. The GT3 car, by rules, has to be RWD and so the elimination of all the AWD mechanical parts, results in a very rear weight bias. As a matter of fact, the Huracan starts with about 60% of its weight at the rear tyres making it practically a very rear heavy car, similar the Porsche 911 that, let me remind you, is rear engined! A car with such weight bias, would need a staggered tyre setup. This means that the rear tyres should be wider than the front, to handle better the different loads.
Unfortunately the tyres offered by the rules, have very similar dimensions for both front and rear which means the mechanical grip is a bit unbalanced with more tyre at the front, than what the car needs.
To the uninitiated, this might sound like a non issue. The car seems to understeer constantly, so more tyre to the front, can only fix the things right? Why does it make it worse then? To have balanced handling characteristics you need to have a predictable rear grip, so that you can shift the weight with your driving inputs and you get back predictable feedback and reactions. If you have more rear grip than front, then you can use the power on the exit of the turns to rotate the car and it will do so gradually, because even if you lose some lateral grip, you still have plenty to handle. But if you have more grip at the front, the moment you get power understeer (and you’ll get it because of the weight bias to the rear), then trying to power oversteer will subtract important amounts of grip from the rear and it will make it skittish and nervous. On top of that, add a quite sensitive aerodynamic platform that we described above, that moves the aero balance heavily to the front and to the rear every time the pitch of the cars changes by mere millimetres and you get a more clear view of why the car requires skills and respect from its driver.
Sounds like a difficult car to handle and it is when you try to push it hard on the limit. Setup must be balanced and on the stiff side, especially at the front. Don’t try to overcome the power understeer with a more oversteer setup, because you’ll end up with a nervous turn in that will make the car slower. Embrace a hint of understeer, be more precise in your inputs and driving line and learn to take advantage of the aero platform and mid turn speed. You can brake late, start to turn in, but get off the brakes as soon as possible and let the car coast to the apex or with a very very slight brake input, anything more and it will understeer at turn in too. Learn to do the coasting part properly and you’ll be surprised by how much speed you can carry inside the turn, which will be translated in time gains outside of the turn. This is taking advantage of the aero platform, leaving the car as flat as possible instead of forcing it to turn by braking and pitching. The results might surprise you.
If properly setup and driven, the Huracan GT3 showcases a very fast turn in and high mid turn speeds. Exceptional traction and agility makes it perfect for slow narrow turns and chicanes. There’s always an understeery behaviour on power at the exit of the turns and generally the car doesn’t like to change its line once in the turn. Precise driving and proper racing techniques are required to make the car deliver, but even thought it might not feel “fun” and requires lots of self control, concentration and commitment, it is capable of blazingly fast laptimes that reward all the hard work.
Assetto Corsa Competizione is available on Steam Early Access now. Currently at build release 3 status.
To keep abreast of all the latest news and discussions from the world of Assetto Corsa Competizione then don't forget to check out our very own ACC sub forum here at RaceDepartment.
Like what we do here at RD? Follow us on Social Media!
To keep abreast of all the latest news and discussions from the world of Assetto Corsa Competizione then don't forget to check out our very own ACC sub forum here at RaceDepartment.
Like what we do here at RD? Follow us on Social Media!
Last edited:
He knows what he is doing.
