Belgian GP 2011 - Spa-Francorchamps

[simieski]

Actually the DRS only works to reduce drag over about 220kph, before that F1 cars pretty much accelerate the same

Which is why we saw barely any DRS overtakes in spain where the cars came out of the final corner at high speed and accelerated to nearly their top speed before DRS was activated.

It's also why we saw loads of overtakes in Canada where DRS was allowed immediately out of a very slow corner.

Sorry, but DRS is at its most effective where it allows the cars to accelerate that tiny bit better out of a slow corner, and get into a slip stream. It's at its least effective when it takes effect at the car's top speed. This is reinforced when the cars are bouncing off their rev limiter, as they will down Kemmel.

Out of a slow corner a car is more likely to be grip limited on getting the power down. Drag is related to the square of a cars velocity so it's increase is exponential with increasing velocity. Decent traction and a good kers I would imagine is the best way to accelerate quickest initially.

[beelsebob]

Which is why we saw barely any DRS overtakes in spain where the cars came out of the final corner at high speed and accelerated to nearly their top speed before DRS was activated.

It's also why we saw loads of overtakes in Canada where DRS was allowed immediately out of a very slow corner.

Sorry, but DRS is at its most effective where it allows the cars to accelerate that tiny bit better out of a slow corner, and get into a slip stream. It's at its least effective when it takes effect at the car's top speed. This is reinforced when the cars are bouncing off their rev limiter, as they will down Kemmel.

Out of a slow corner a car is more likely to be grip limited on getting the power down. Drag is related to the square of a cars velocity so it's increase is exponential with increasing velocity. Decent traction and a good kers I would imagine is the best way to accelerate quickest initially.

Yes, drag is related to the square of the car's velocity, but that is not equal to DRS being most effective at high speeds. There are many other factors involved. For example, if you are too far back, and caught in the car in front's turbulent air, there may be so many crazy eddies being pushed over your car's surfaces that the drag created is far higher than anything DRS can cancel out. This is my best guess for why we've seen empirically, DRS being more effective at giving you that little acceleration boost out of a slow corner that gets you into the slipstream, rather than being effective at simply giving you a higher top speed.

The bottom line of what I'm saying is that my hypothesis at the beginning of the season would have been the same as yours – that DRS should be effective at high speeds. The empirical evidence says this isn't true, and that it's effective at getting you accelerated better.

[i70q7m7ghw]

Actually the DRS only works to reduce drag over about 220kph, before that F1 cars pretty much accelerate the same

Which is why we saw barely any DRS overtakes in spain where the cars came out of the final corner at high speed and accelerated to nearly their top speed before DRS was activated.

It's also why we saw loads of overtakes in Canada where DRS was allowed immediately out of a very slow corner.

Sorry, but DRS is at its most effective where it allows the cars to accelerate that tiny bit better out of a slow corner, and get into a slip stream. It's at its least effective when it takes effect at the car's top speed. This is reinforced when the cars are bouncing off their rev limiter, as they will down Kemmel.

Sorry but you've got it the wrong way round.

DRS is less effective at low speed, and they need any downforce they can get to provide maximum traction at the rear so there's little point in activating it.

As the speed increases, DRS becomes more and more effective. Drag squares with speed, so DRS is more and more effective as speed increases. The difference in drag between a car with DRS enabled and car without is greater at 200mph than it is at 100mph.

Cars bouncing off the rev limiter is a gearing issue, and occurs because they car achieves it's top speed earlier than it was geared for. This can happen for many reasons, a slipsteam, better traction through the acceleration zone, deployment of DRS, etc.

[HampusA]

Yes that´s true but you are still locked in seventh gear that has been compromised right from the start due to the fact that DRS is ok to use everywhere in Q sessions.

That´s why he says it´s not so effective at top speed because you will hit the limiter.
From maybe 160-170km/h and up is where the DRS does it´s job the best.
It reduces the drag on your way to topspeed.
Which is far more effective then reducing drag while at top speed since you have a compromised seventh gear.

[beelsebob]

Sorry but you've got it the wrong way round.

DRS is less effective at low speed, and they need any downforce they can get to provide maximum traction at the rear so there's little point in activating it.

As the speed increases, DRS becomes more and more effective. Drag squares with speed, so DRS is more and more effective as speed increases. The difference in drag between a car with DRS enabled and car without is greater at 200mph than it is at 100mph.

Cars bouncing off the rev limiter is a gearing issue, and occurs because they car achieves it's top speed earlier than it was geared for. This can happen for many reasons, a slipsteam, better traction through the acceleration zone, deployment of DRS, etc.

That's a lovely theory – but the empirical evidence says otherwise. When DRS is allowed on long straights but not in the area after the corner before it, it does not create many overtakes. When it is activated straight out of a slow corner it does.

As HampusA says - you don't arrange your gears to allow DRS to increase your top speed significantly, because it breaks your gearing otherwise. Instead, you use DRS to reduce your drag while accelerating, and hit that top speed faster. You also use it to get you *into* the slip stream.

Bottom line – every track where DRS has been activated half way down a long straight, or after a fast corner has resulted in very few overtakes from it. Every track where DRS has been activated out of a slow corner into a decent length straight, it's provided a good amount of passing.

[Richard]

Is that a DRS effect, or simply that slower corners give more opportunity to overtake anyway? DRS would enhance that natural effect.

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7th gear is compromised by the race conditions not qualifying. If 7th was optimised for quali (low fuel with high use of DRS) then they'd rarely hit the limiter in the race (high fuel and limited DRS).

The optimum use of DRS will be when you can get rid of surplus downforce without hindering traction. That is dependent on what % of total downforce is lost when the wing is open. If more of your downforce is generated by the floor then you can afford to open the DRS earlier.

Similarly, we see different implementations of DRS with large and small flaps. These will vary in the downforce they shed, hence when they can be safely opened.

The flip side is that a car with more downforce can carry more speed through the corners. SO a team may choose to put more down force on the flap for that reason. however more downforce on the flap means less use of DRS, but the greater apex speed compensates for less effective DRS on the straights.

Its swings and roundabouts, also it is the relative performance of one team relative to another, rather than an absolute answer.

[beelsebob]

Is that a DRS effect, or simply that slower corners give more opportunity to overtake anyway? DRS would enhance that natural effect.

Sure – absolutely it's to do with slow corners helping you get close to the car in front... But the result of that is... DRS is most effective when placed on straights just after slow corners which aren't quite long enough to mash the rev limiter with the DRS open.

The Kemmel straight doesn't fit either of these properties. The cars bounce off the rev limiter *even without* DRS, and it's immediately after one of the fastest corners in F1.

[HampusA]

EDIT: read wrong, sorry.

[i70q7m7ghw]

Sorry but you've got it the wrong way round.

DRS is less effective at low speed, and they need any downforce they can get to provide maximum traction at the rear so there's little point in activating it.

As the speed increases, DRS becomes more and more effective. Drag squares with speed, so DRS is more and more effective as speed increases. The difference in drag between a car with DRS enabled and car without is greater at 200mph than it is at 100mph.

Cars bouncing off the rev limiter is a gearing issue, and occurs because they car achieves it's top speed earlier than it was geared for. This can happen for many reasons, a slipsteam, better traction through the acceleration zone, deployment of DRS, etc.

That's a lovely theory – but the empirical evidence says otherwise. When DRS is allowed on long straights but not in the area after the corner before it, it does not create many overtakes. When it is activated straight out of a slow corner it does.

As HampusA says - you don't arrange your gears to allow DRS to increase your top speed significantly, because it breaks your gearing otherwise. Instead, you use DRS to reduce your drag while accelerating, and hit that top speed faster. You also use it to get you *into* the slip stream.

Bottom line – every track where DRS has been activated half way down a long straight, or after a fast corner has resulted in very few overtakes from it. Every track where DRS has been activated out of a slow corner into a decent length straight, it's provided a good amount of passing.

It's not a theory, drag squares with speed, fact. DRS is more effective at higher speeds than it is at lower speeds.

The slip stream would cause the same gearing problems DRS causes.

DRS is more effecive on those tracks because the zone has probably been longer. Regardless of where it's activated, if it's active for longer it's always going to be more effective, subject to gearing.

[beelsebob]

It's not a theory, drag squares with speed, fact. DRS is more effective at higher speeds than it is at lower speeds.

The slip stream would cause the same gearing problems DRS causes.

DRS is more effecive on those tracks because the zone has probably been longer. Regardless of where it's activated, if it's active for longer it's always going to be more effective, subject to gearing.

You are correct – it is a fact that drag squares with speed... that does not translate to "DRS is more effective at higher speeds" that translates to "the drag reduction is increased at higher speeds". The goal of DRS is not to reduce drag, it is to increase overtaking. You have several steps missing in your logic.

Re the length of the zone – that does not square with the evidence either. Spain's DRS zone was 830m long, Canada's first, where all the overtaking happened was only 800m long.

[i70q7m7ghw]

The goal of DRS is not to reduce drag.

DRS = Drag Reduction System

[beelsebob]

The goal of DRS is not to reduce drag.

DRS = Drag Reduction System

Who said that a name had to reflect the goal? Perhaps here it reflects the method instead .

[wesley123]

The goal of DRS is not to reduce drag.

DRS = Drag Reduction System

Who said that a name had to reflect the goal? Perhaps here it reflects the method instead .

It's goal is to reduce drag, allowing higher top speed making overtaking easier.

[i70q7m7ghw]

I do agree with you in a way beelsebob, I'm also not a fan of these activation points halfway up the straight. A better way of doing it might be a time based amount of usage on the straight, so they can deploy it were they like (on the straight) but it'll only last a set time/distance.

I agree, it does seem more effective off the back of a slow corner, but not always, and it's nothing to do with hitting the rev limiter. The cars are closer together coming out a slow speed corner because the effect of turbulent air is greatly reduced.

[beelsebob]

It's goal is to reduce drag, allowing higher top speed making overtaking easier.

Right – the goal is to make overtaking easier. This is done by reducing drag.

This is not equal to "maximum possible drag reduction implies maximum possible chance of overtaking". Instead, perhaps "drag reduction when you're not yet in significant dirty air because the car in front isn't moving so fast yet gives more chance of overtaking" or "drag reduction while accelerating causes you to get into the slip stream, multiplying the effect of the drag reduction and making overtaking easier."

I do agree with you in a way beelsebob, I'm also not a fan of these activation points halfway up the straight. A better way of doing it might be a time based amount of usage on the straight, so they can deploy it were they like (on the straight) but it'll only last a set time/distance.

That's a remarkably neat idea actually.

I agree, it does seem more effective off the back of a slow corner, but not always, and it's nothing to do with hitting the rev limiter. The cars are closer together coming out a slow speed corner because the effect of turbulent air is greatly reduced.

You're right – dirty air through a fast corner preceding the activation zone is a good chunk of the reason. Which is one reason why the Kemmel straight is a terrible idea. The rev limiter is also significant here though – in Spain for example, and I would bet heavily in Belgium, the cars will be scraping the rev limiter at the end of the straight, and will certainly be bumping it with DRS open.