Tech: What went wrong with Alonso's DRS?

Sunday 21st April 2013, 21:10 by TF1T Staff 

Fernando Alonso suffered a rather unique problem at the Bahrain Grand Prix which saw his rear-wing remain open after activation - with no way to return it to the closed position other than stopping and allowing his mechanics to force it shut.

This is the first time we've seen DRS fail this season. In fact, only on one other occasions have we seen the system fail in the open position since it was introduced in 2011 - Michael Schumacher at the 2012 Canadian GP.

DRS has failed numerous times in the closed position, but this isn't such an issue, as the downforce and balance of the car isn't affected.

However, should it fail in the open position as it did with Alonso, the cars balance changes dramatically, rear-downforce is severely reduced and the car becomes quite unstable through the corners.

The Spaniard, who eventually finished eighth without the artificial aid, did a great job driving his car around the Sakhir circuit with the open wing for three laps before the team called him in to the pits - on two occasions - to close it manually.

It's such a unique failure because DRS is designed, should it fail, to close automatically. This wasn't the case for Alonso.

The system on the Ferrari uses an actuator positioned above the lower-plane of the rear-wing (as is the case on almost all the cars now), which pulls the wing open by hydraulically moving a small piston connected to the upper-plane.

As per the regulations, the wing can only move to reveal a 50mm gap. In Alonso's case, it would seem the actuator has exceeded its limit and the wing has opened more than the allowed 50mm.

To close the flap, the hydraulic pressure is released and the wing should return to its closed position with the aid of the airflow running over the top. In this case, because it's opened further than it should have, the airflow is doing the opposite and is forcing it to stay open, rather than forcing it closed.

The 'stopper' inside the actuator is supposed to stop the piston from travelling too far. It seems in this case, it's failed and cost Alonso a handful of points and, according to Ferrari, the race win.

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