Fernando Alonso goes into his home Grand Prix at Barcelona next weekend looking to bounce back from the disastrous Bahrain Grand Prix in which he lost a chance of victory due to a failure on the Drag Reduction System rear wing.
It means that after four rounds of 19, he now lies 30 points behind title rival Sebastian Vettel.
The fallout from the DRS failure is interesting. According to a statement from Ferrari, “Analysis revealed that the problem was caused by the breakage of a mechanical component within the system. It’s the first problem of its kind on this system seen in the three years during which it has been used.
“The failure is not something that causes concern for the long term.
“The disappointment at what happened is even greater when one looks at the usual analysis of performance over the race weekend, which shows that Alonso could definitely have been fighting with Sebastian Vettel for the win.”
In terms of its impact on Alonso’s race, he had already lost the initiative to Vettel on the opening lap, so was in chasing mode. But then the DRS jammed open he was forced to pit on lap seven. Experts suggest that with the DRS stuck open the loss of downforce would be around 70 to 80 points of downforce. Alonso lost three seconds on lap 7 and then a further four seconds with it stuck open again on lap 8.
Not only did the wing not close, it went back into an “over centre” position.
There have been isolated incidents where a wing failed to close, such as Mercedes in Montreal last year. But this was different due to its finishing position.
Interestingly, the problem in Bahrain showed that the Ferrari hydraulic system for the wing is apparently relatively simple; a single acting actuator relying on a spring or gas spring to close the flap and probably a solenoid to energise it. This is why the mechanics could close the flap manually and it remained so on track (unlike the Mercedes failure last year which was caused by trapped hydraulic pressure). There are other ways to plumb the system for example by using hydraulics to both open and close the flap via a double acting system.
After it failed the first time, it was obviously a mistake on Alonso’s part to use it a second time on lap 8, as this cost him another 21.5 seconds for a pit stop. It also put him back in traffic. But to try to do the rest of the race without DRS would have meant he would be uncompetitive anyway. Nevertheless, he did managed to come some way through the field to finish eighth.
One thing is for sure; the design of the DRS from now on should be such that in the even of a failure it stays closed, rather than the opposite. To prevent an ‘unsafe’ failure like this should preclude the mechanism being able to go over centre. This is encapsulated in article
3.18.1 of the Technical Regulations.
“The design is such that failure of the system will result in the uppermost
closed section returning to the normal high incidence position.”
The hydraulic system runs up the side of the rear wing endplate and then serves the torpedo shaped actuator on the rear wing. It is very aggressive on DRS wings, it has to be as it’s pushing flap up when loaded with air pressure. There is a stop to ensure that it sets in position quickly and clearly the Ferrari one went past its stop.
Teams design the profiles of the rear wing upper and lower elements to give the maximum possible reduction in drag when the flap is opened to the 50mm slot gap allowed. This affects the shape of the flap, usually forcing a less cambered (flatter) profile and therefore one that is more likely to go over centre.
The failure of the mechanism on Alonso’s wing, presumably caused by just a small amount more wear, free play or deflection in the mechanism than anticipated, could be an example of how much work has gone into the wing and how near to the limit they are pushing it.