Sunday, 3 April 2011

So How the Heck Does DRS Work?

DRS or the Drag Reduction System is a new feature of F1 this year and I think its going to be one of the more important features of the championship. So I thought I would spend a little while explaining how it actually works because as usual, what started out as a simple idea has been made a little more complicated than it should be.

First off the easy bit, what is DRS. From a mechanical point of view all it consists of is a moveable element in the rear wing. The driver pushes a button, one of the rear wing sections moves to be flatter to the air. Drag is reduced and the car goes faster, simple! This is obviously only useful on straights because it also reduces grip. The car apparently loses around 5% drag so we can assume its at least that much  in grip too. On corners this can be regarded as a 'Bad Thing'. Now a higher top speed means that compared to another car without the DRS system activated you stand a far better chance of being able to get in front before the next corner. Now comes the tricky bit!

During the race you don't want everybody to be able to use the Drag Reduction System at the same time. If they did there would be no relative difference in the cars and the standard no-overtaking races would continue. A scheme was hatched! "What," thought some bright spark somewhere in the Formula 1 control centre, "if only a driver who was close enough to have a chance at overtaking anyway could use his DRS?" That is the simplest explanation, so here comes the tricky bit, how to do that fairly.

Two lines are marked on the track before the start/finish straight. The first of these is used to check the gap between any pair of cars. If two cars are within one second of each other (i.e. pretty close!) then the second of them gets a nice light appear on his wheel saying "DRS active". This is good news because it means that after the second line the following driver can hit his DRS button and go faster. The lead driver however, gets nothing and so has to prepare to defend, hard. Once the DRS button is pressed the flap will stay flipped until the driver hits the brake again (i.e. the first time he needs some grip again!).

Slightly confusing the issue again is the fact that the second line (the "press your button" line), seems to be before the last corner. But because they need grip to get round it, the driver doesn't dare push the button until he has made it to the straight. Allegedly if there are more than two cars in a group, all less than a second behind the next car, all the following drivers will be able to push the button. Which should lead to some major entertainment at the end of the following straight!

Now the bad news. This is only a 5% reduction in drag. Its not much and its only drag. In theory that's good for 12 km/h difference in speed by the end of the straight. Which means less than that most of the way down. In Australia that didn't seem to be enough to get properly alongside another driver. With longer straights hopefully it will be.

Of course we don't want any changes and confusion during practice and qualifying, (heaven forbid) so the system is active for everyone all the time. This does allow people (*cough* Sutil) to get it horribly wrong when they move their movable rear wing a little too soon, which is always fun! But it also allows the teams to get the gearing right for the higher speed down the main straight.

There is a chance that it will make overtakes seem a bit cheap, but I'm open to seeing if it makes the race more unpredictable. Fingers crossed it spices the show up rather than dumbing it down. Roll on Malaysia!


  1. I think that the reason they loose grip it's not because of the reduced drag but because of the reduced down force. In this case, down force decreases when the wing profile changes to have a lower drag, therefore using the DRS in a corner will lower the grip where the grip plays a too huge role

  2. Yes you're right. Downforce and drag are very closely linked, and most of the time if you reduce drag you also reduce downforce.

    One of the jobs of aerodynamics engineers is to try and get more downforce with less drag. Not easy to do!

  3. Nice explanation, whoever wrote this - thanks! I've been looking for a simple, clear explanation all over the place, and Martin Brundle seems to think everyone should know exactly how it works by now and doesn't bother to explain. I shouldn't have missed the beginning of the season. As to whether it will actually work, ie making racing and overtaking more exciting, I think remains to be seen - but not too much evidence of it so far
    . Not quite at NASCAR levels yet.....
    One more question - can you use DRS and KERS at the same time?

  4. Definitely not NASCAR Levels of overtaking, I don't think we would be able to keep up! :-)

    Its always been claimed that the idea is to get cars alongside each other so that the driver still has to work to make a pass. There are some stats somewhere about overtakes this year vs last and there is an effect. But the new Pirelli tyres are having an effect too, so its hard to separate them.

    KERS and DRS are allowed together. You sometimes get team radio telling the following driver to save KERS until the DRS zone to get a double boost.

  5. This entry from the BBC site made my head spin... "When the DRS flap opens on the Mercedes it reveals a duct, into which the air flows before being directed back through the bodywork of the car and on to the front wing."

    Air moving 4 times faster backwards in order to be used again? Sumfing Wong with that quote I think.

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