Red Bull’s clever mechanical systems explained
This article has been kindly translated from German to English and originates from AMuS.
After the summer break Red Bull have left their opponents trailing in their wake, but this time not just from an aerodynamic perspective. As auto motor und sport report in their latest issue (21/2013) there is more to the Red Bull performance than only the most downforce.
No car on the grid sticks to the road in right angle bends like the Red Bull and there is none that accelerates as cleanly. At 100 kph mechanical and aerodynamic grip are in perfect balance. Like no other, Adrian Newey knows how to make the tyres work using camber, toe-in and damper settings. The Austrian team has obviously worked out how to get the tires up to speed even with the latest restriction on use of tyre heating.
Same pitch (rake) as 2011
Red Bull also generates more downforce using exhaust gases more effectively than the other teams. This is a big advantage at lower speeds, when aerodynamics are less effective. This is why Newey can pitch the cars (front low, rear high – ‘rake’) like he did in 2011, when Red Bull demolished the field.
To deliver this the exhaust gasses must seal the diffuser permanently, even when breaking or when applying partial throttle in corners. More downforce prevents the rear wheel from spinning or locking under breaking. That eases the strain on the rear tyres.
Mid season tyre change unmasked the RB advantage
The tricky bit is to use the exhaust gasses permanently. The rules make it a lot more difficult than in 2011. Late ignition in the so-called ‘four cylinder mode’ is now allowed only in a very restricted way. The teams had to decide their engine mappings at the start of the season and are only allowed to deviate from them by 2%.
It appears that Red Bull and Renault have had a distinctive advantage in this regard from the very start. It only wasn’t visible so clearly, because unpredictably early season Pirelli tyres countermanded this advantage. Too much downforce was counter-productive, because the tyres couldn’t cope with the loads.
When Pirelli brought back the 2012 construction, Red Bull was helped in two regards. They could lower the front, therefore increasing the rake of the car and the tyres were more predictable and constistant since the reintroduction of the Kevlar belt.
Vettel adapts his skills in the simulator
But what has made the Red Bull so dramatically quick in Singapore? Where are the 1.5 additional seconds per lap? And why only Vettel and not Webber?
To forestall any conspiracy theories – the cars are absolutely identical, but the drivers have to use the technical advantage effectively and Vettel is much more adept at counter intuitive driving styles than Webber. However, this isn’t necessarily merely natural gifting because Vettel has been spending day and night in the simulator before each and every race. Immediately after his win in Singapore he flew back to England for simulator duties.
He will have to adapt his driving style again for Korea, because Renault re-programs the engine software for every race. The unorthodox driving style required has to be learned and turned into instinct. Only thus the gift of better exhaust gas use can be converted into lap times.
What do the misfires in corners mean?
What RB and Renault have discovered, leaves even the opposition guessing. They try to uncover the secret using complex sound recordings, but as yet have not yet succeeded. This analysis reveals Vettel’s car seems to be misfiring between steering into the corner and reaching the apex, while at the exit the car sounded as if Vettel only applies partial throttle.
The engine electronics are cleverly programmed, the gearbox ratio is perfectly setup and Vettel’s driving style minutely prepared so that the exhaust releases gas in all phases, even while the engine is towing and therefore the sides of the diffuser remain perfectly sealed. That means more downforce in the corners.
During acceleration a crude form of traction control is simulated and that’s completely legal, too. The problem that Ferrari and Mercedes are facing is, that they cannot react, even if they find out what RB and Renault are doing. They are in the 2% jail of their pre-season engine mappings.
What is the four-cylinder mode
The rules governing the legitimacy of this technique are the same for all teams. The throttle valves are allowed to follow throttle input with a delay of 50 milliseconds and at times when the car is just using four cylinders, late ignition is allowed if the driver requests less than 50% torque as should be available at the current rev count via throttle input. This is called ‘four-cylinder mode’.
During each gear change four cylinders ignite after a delay of 50 milliseconds. This delivers exhaust gasses and therefore downforce when shifting down. The opposite happens during acceleration. The driver floors the throttle momentarily, but that command arrives at the engine with a short delay. If the driver then precisely reduces throttle input, so that he demands less than 50% torque of what the current revs should be delivering the requirements for four-cylinder mode are met again.
In the small breaks required for gear changes, at least in lower gears, the four-cylinder mode can be engaged in small intervals of 50 milliseconds. If the gearbox ratio is short, the team can reduce and control power delivery in the critical lower gears. There are theories that Red Bull use KERS not only for extra power, but also to countermand too rapid torque delivery in the early acceleration phase.
Red Bull and Renault run special programs
What sets RB and Renault apart from the other teams is which particular four cylinders of the eight are used for in ‘four-cylinder mode’. Since the engine sometimes sounds distinctively unhealthy, experts suspect that Renault in the Red Bull doesn’t simply switch of one of the two cylinder banks, but actually four cylinders in a V configuration. The questions is, which ones and in what sequence.
The purpose is to deliver the artificially produced exhaust gasses as hot as possible. The more the gases are concentrated, the more downforce is produced. If two cylinders on each side are used in four-cylinder mode, the amount of additional exhaust gasses on each side of the diffuser is equal and the sealing of the diffuser is permanent. But maybe that’s not what Red Bull always want.
On a track like Singapore, the rear suspension is setup relatively soft, so that the tyres have maximum of grip. That causes a considerable longitudinal roll. The diffuser is lifted higher on the inner side of the corner and needs more exhaust gasses to seal it effectively.
It is possible that in that the engine is phasing at this time three cylinders on the inner bank and one on the outer bank in the four-cylinder mode. Interestingly enough Red Bull always uses the flowviz paint only on one side of the car in Friday practice. In Singapore it was the left side on Vettel’s car and the right side on Webber’s. Obviously Red Bull evaluate the airflow on each side of the car individually and independently.
Red Bull with shortest gear ratio
This whole effort is a useless unless the gearbox ratio is perfectly tailored to suit the requirements. The more the engine is under load, the better downforce is generated through exhaust gasses; the shorter the gear ratio, and therefore the need to shift more frequently, means the four-cylinder mode can be activated more often.
The speed traps at Singapore demonstrated that Red Bull went all out on delivering the maximum number of shifts. Both cars where by far the slowest in terms of top speed with Webber being clocked at 293 kph and Vettel at 283 kph. The difference is due to the fact that as race leader, Vettel never was in a position to use DRS.
The opposition was much quicker than Webber. McLaren managed 301 kph, Mercedes 300kph and Ferrari 298 kph. But in contrast Red Bull at 244 kph were the fastest on the finish straight, which comes shortly after turn 23. Vettel gained his time in the corners, not on the straights.
Indeed this is a most sophisticated partnership between Renault and Newey as together they develop both the mechanical and aerodynamic performance to work in harmony.