Sebastien Buemi and the Renault team stole the headlines after the first pre-season test at Donington Park, but what did we actually learn about the upcoming season? Buemi was fastest, but Daniel Abt held the fastest first and second sectors, before traffic at the final corners slowed him down. With only a limited amount of qualifying sim laps available, the German couldn’t have another attempt at topping the timesheets. But out and out lap time is not what these pre-season tests – or in fact the new technical changes – are about.
For season two, teams can manufacture their own powertrain. The powertrain is essentially the components that take energy from the battery and make it turn the wheels. Fundamentally this comprises the inverter, electric motor and gearbox. Because each team is still using the same battery, don’t expect too much difference in pure one-lap pace. The key is efficiency.
The most noticeable differences between the various manufacturers is the number of gears. Although electric motors have instant torque, gears can still prove advantageous when it comes to maximising this power. Last year’s car had five forward gears, so for Team Aguri – which is still using last year’s powertrain – that will remain the same. Despite using an upgraded McLaren motor, Mahindra has dropped to using four gears, as has Venturi. At the other end of the spectrum, you have NEXTEV TCR and DS Virgin, who have both decided to use a direct drive system, effectively one gear.
In Argentina last season there were 23 gear changes per lap. A gear change takes roughly 0.05 seconds, so over the course of one lap the car spends 1.15 seconds out of gear, with no power being delivered to the wheels under acceleration, and no regen braking when slowing the car down. Eliminate the need for gear changes, and you could save yourself a valuable amount of time. The fact that so many different solutions have been implemented is one of the most fascinating changes for the new season. Renault for example, is using two gears, while Abt is employing three. These might be small differences, but as we saw in London at the end of last season, winning titles depends on such things.
These different executions of the new rules also create different sounds. The DS Virgin car is quiet and smooth, while the Abt machine has a high-pitched whistle in addition to the regular electric motor sound. This really helps in demonstrating that Formula E has moved away from being a one make series, and development is key.
NEXTEV had a difficult pre-season test at Donington. Having run a pretty successful test period until the public sessions, it all unravelled on the Monday at Donington. Defending champion Nelson Piquet Jr stopped on track twice, forcing the team to send the motors away to figure out the problem, ruling them out of Tuesday’s running.
Its problems, though, paled into insignificance compared to Andretti and Trulli. After no running on Monday, Andretti made it to the track on Tuesday. Simona de Silvestro was at the wheel, as the car left the pits. The car made it to the Old Hairpin before grinding to a halt. The red flag was thrown, and team personnel hopped in a course car to go and assist. They got the car moving again for another two corners before its next failure. The process was repeated and another two corners were completed, then with one final restart the Andretti car returned to the pits, after around 15 minutes on track. The car and team are clearly behind the development curve at the moment, but there’s no doubt they have the skills to turn it around.
The Trulli team meanwhile failed to get on track at all. Jarno got behind the wheel on Monday, and the car moved under its own power into the pitlane, before coming to a stop just outside the garage. The team have now decided to postpone the shakedown until the second set of test dates.
As ever with pre-season testing, it’s much easier to see who’s struggling than who is running well. Without knowing the battery energy percentages it’s impossible to have any grasp on which manufacturer has created the most efficient solution. Simply on the basis of the two Donington tests so far, you’d have to conclude that Renault e.dams, Abt and DS Virgin are looking strongest, but there’s still a lot of mileage to come before the season starts in Beijing.
Published on 13th August 2015