| | | Effective PR

F1: Rosberg or Hamilton crash, Spain 2016 - who is to blame?

Bryan Edwards

Niki Lauda shoots from the lip and is consistently quick to blame Hamilton for any incident involving the two Mercedes drivers. Toto Wolff is far more measured. Within minutes of Mercedes' premature end of the Spanish Grand Prix, both had delivered their verdict. Lauda was, as usual, critical of Hamilton. Wolff gave a technical answer that hardly anyone understood but it did not say Hamilton was to blame. And it was right that it did not because while we mortals do not have access to Rosberg's data, we do have access to Hamilton's in-car footage and while we cannot say Rosberg was at fault, we can say, with certainty, that Hamilton was not.

Lauda is quoted in today's media as saying that Hamilton was "stupid." He was not. Indeed, he was far from stupid, as the in-car footage shows.

Here's exactly why Hamilton did the right thing but suffered the wrong consequences.

Rosberg shot of the line and was ahead of Hamilton. But Hamilton, on approach to turn 4, was travelling much more quickly than Rosberg. Expecting Rosberg to cover the inside of the right-hand bend, Hamilton set up his car to go around the outside of Rosberg.

Then, as the in-car footage clearly shows, Rosberg's power harvesting light began to flash.

Point 1: the light is not a brake light and pressing, or not pressing, the brake pedal has no effect on it. The light flashes when the engine is harvesting electric power for the hybrid system instead of driving the car forward: in short it is, in effect, a deceleration light. But it does not come on every time the driver lifts his foot from the throttle; what happens then is that the car rapidly decelerates before starting to harvest electricity. So when the light flashes, it's saying "this car is slowing down."

It is extremely unusual for a car to start to harvest in the approach to a corner : there is good reason for this, not the least of which is that the engine is needed to maintain the car's balance. Therefore the flashing light signalled to Hamilton "there's something strange happening to Rosberg's car."

Point 2: the effect of taking off power going into a corner is that the car drifts off-line and drifts outwards, it's similar to but not the same as centrifugal force. So, Hamilton got a warning that Rosberg's car was going to drift left - right into Hamilton's planned path. And that's what Rosberg's car did.

Hamilton therefore did the right thing and changed to go to the right of Rosberg, now taking the inside of the corner.

Point 3: there is an old adage in racing - if there is an accident, drive at the point where the car is because by the time you get there, the accident will have moved. So by that principle, by aiming at Rosberg's car which, by the time Hamilton moved across, was already drifting left, Hamilton was pointing at a piece of track that would be empty by the time he got there.

Point 4: when a car accelerates out of a corner, it turns into the corner (that's why cars spin if too much power is applied to the rear wheels: they pivot around the front wheels). For some reason that we do not know, Rosberg or his car opened the taps just as Hamilton was alongside him. It is very unlikely that Rosberg knew Hamilton was there because of poor visibility, the fact that Hamilton had been on the other side a split second earlier and because Rosberg was dealing with whatever was causing his car to misbehave. In saying this I give Rosberg that benefit of the doubt that he was not deliberately going slowly into the corner to unsettle Hamilton. When Rosberg's car accelerated, it turned in leaving Hamilton two choices: hit his team mate or take to the grass. He chose the latter but, under full power, as soon as his back wheels touched the grass, he was in the position of applying too much power to the rear wheels. The car snapped around, the rear travelling faster than the front and - it has to be noted from overhead footage - travelling faster than Rosberg's car, and smacked into the rear of Rosberg's car, taking them both out of the race in a shower of carbon fibre and other parts.

Some say that Rosberg defended but that is not how the physics plays out: to understand this crash, here's the science bit.

Momentum and forces play on Formula One cars just as they do on any other object. The purpose of most F1 design from tyres through suspension to aerodynamics is to counter those forces of physics. Fat sticky tyres are used to combat the tendency of an object to go in a straight line: put a peg on the end of a piece of string and swing it in a circle: the string goes tight not because the peg is going in a circle but because the peg is trying to fly off in a straight line, called a tangent. Loose go of the string and the string and peg fly away. In a racing car, anything that destabilises the delicate balance between tyres and road cause the car to go off-line. That's why Rosberg's car drifted left and it's why Hamilton was right to assume that it would continue to go left.

Lauda needs to think before he speaks. Wolff needs to explain more: his terse comment that Rosberg's car had what can be summarised as an incorrect engine mode at the critical time has not been given sufficient profile. That certainly fits with the knowledge that the red "harvesting" light was flashing at a point where it should not have been.

The stewards investigated and decided not to penalise either driver: that decision is right. Arguably, a technical failure or at least a "glitch" triggered the events that took out both drivers.