2013 Belgian GP - Spa

[beelsebob]

They didn't entered Pouhon with DRS, but right after getting on the power mid corner, they opened it up.

The point being that they couldn't keep it open at the 250km/h that they enter that corner at, so it needs to be tuned above 250km/h.

Both Rivage and Fanges are slower corners. The drag penalty of the rear wing isn't an issue there, so why even bother stalling the rear wing even if it was possible (certainly is not).

Even at the 160km/h that the left hander after rivage is taken at, you're still paying a significant drag penalty.

However, if you tune the DRD so that you run more rear wing for the same top speed as without DRD

This will still make you slower down the straights, as you will be slower right up to the point where you hit max speed due to the increased rear wing drag.

you have more downforce thus more speed in les combes, rivage, fanges, stavelot and perhaps even the bus stop chicane.

Indeed, so you might make up some of the time you still lost on the straight (possibly all of it, but probably not by a considerable margin).

DRD really should be set up for more downforce in these corners instead of more top speed for the same downforce.

Again, if you do this then you lose time all the way down the straight, the acceleration curve flattens out, and then hits it peak more sharply.

Btw, you just name almost every single corner except the slowest ones on Spa.

Yes, yes I did, because almost every single corner at Spa is high speed and needs the downforce still working

There is not a single circuit last year on which teams drove through with DRS so much of the circuit. If that was possible in the first place, teams wouldn't bother mounting a rear wing.

Again, this does not matter. The key is not "how many corners can I drive through with DRS open", but "at what speed am I able to calibrate the DRD to open". The two are fundamentally different – one can be opened by the driver at will, the other can only be opened at a certain speed. For the latter to work well, that speed needs to be a low speed, at spa, it can not be a low speed.

[turbof1]

I have a fear for answering each individual line, because the risk is there it will be further chopped down. Please don't do that . I am going to answer just this one line:

Yes, yes I did, because almost every single corner at Spa is high speed and needs the downforce still working

Wut? Corners like Rivage and Fagnes are pretty slow corners, medium at best. And of course you need the downforce in those corners, because their speed in those is too low for the diffuser to produce enough to replace the rear wing. The drag penalty in those corners is virtually not existent.

And btw, nobody enters Pouhon at 250km/h. At best 240km/h.

[beelsebob]

So, I just did some googling, and discovered that Caterham are awesome, and have been publishing speed traces for all their races; and that Lewis Hamilton is awesome, and *cough* "published" *cough* a speed trace for Spa. I then looked at the fastest point on the track where drivers were not able to open DRS on each circuit, and computed the proportion of the time they're above this speed. This gives us a pretty good indication of the point at which DRD can be calibrated to open at a given circuit, as it tells us roughly for what proportion of the lap the DRD will be able to open.

The results:
Australia: 78% of the lap
Malaysia: 30% of the lap
China: 59% of the lap
Bahrain: 69% of the lap
Spain: 31% of the lap
Monaco: less than 5% of the lap
Canada: 73% of the lap
Britain: 21% of the lap
Germany: 52% of the lap
Hungary: 63% of the lap
Belgium: 27% of the lap.

So, places you absolutely do want DRD:
Australia, Canada, Bahrain, Hungary

Places you gain very little from DRD:
Monaco, Britain, Belgium, Spain

Long story short – stop go circuits, and mid speed circuits = DRD heaven. High speed circuits, and constant low speed circuits = DRD hell.

Spa is not a place where DRD will gain you a lot relative to other tracks.

[Mika1]

Mercedes won't use DRD in Belgium or Italy, they wanted to test the system during the YDT, they couldn't, so they need more time (FP1 sessions) to test/develop the DRD system.

[turbof1]

So, I just did some googling, and discovered that Caterham are awesome, and have been publishing speed traces for all their races; and that Lewis Hamilton is awesome, and *cough* "published" *cough* a speed trace for Spa. I then looked at the fastest point on the track where drivers were not able to open DRS on each circuit, and computed the proportion of the time they're above this speed. This gives us a pretty good indication of the point at which DRD can be calibrated to open at a given circuit, as it tells us roughly for what proportion of the lap the DRD will be able to open.

The results:
Australia: 78% of the lap
Malaysia: 30% of the lap
China: 59% of the lap
Bahrain: 69% of the lap
Spain: 31% of the lap
Monaco: less than 5% of the lap
Canada: 73% of the lap
Britain: 21% of the lap
Germany: 52% of the lap
Hungary: 63% of the lap
Belgium: 27% of the lap.

So, places you absolutely do want DRD:
Australia, Canada, Bahrain, Hungary

Places you gain very little from DRD:
Monaco, Britain, Belgium, Spain

Long story short – stop go circuits, and mid speed circuits = DRD heaven. High speed circuits, and constant low speed circuits = DRD hell.

Spa is not a place where DRD will gain you a lot relative to other tracks.

I like the statistics, but... the conclusion you make out of it is just faulty. It doesn't even include time spend on accelerating, the % of laptime the slower corners equal to, and so on. Think of a circuit like the old Hockenheim, before that even had the chicane. One slow sector and for the rest pure flat out. What are you going to win most with: a very small bit of extra top speed, or a bit more wing angle on a very flat rear wing? 2% of extra top speed in 2 sectors or 8% more speed in the slow one?

Sorry mate, I do appreciate the effort you put in it, but your proposed model is just too simplistic. There is more to such comparisons then the percentage above stall speed. Plus you forget you can slow down more to artificially lower the turn over point. Say they slow down to 220km, how big will the percentage then? What about 200? As long as the drd makes up for the lost time for one corner, teams and drivers will do that

[beelsebob]

I like the statistics, but... the conclusion you make out of it is just faulty. It doesn't even include time spend on accelerating

That's the point – DRD does not work while accelerating to the trigger speed. DRS and the F-duct do, that's why they worked excellently at Spa. The DRD is triggered at a set speed, it does not work below that speed, it does not work while accelerating up to the trigger speed.

The only relevant time with DRD is the time spent above the trigger speed.

If anything, your acceleration with a DRD on the car will be slower because you are carrying more wing, hoping to off set it in the top registers of speed with the DRD.

One slow sector and for the rest pure flat out. What are you going to win most with: a very small bit of extra top speed, or a bit more wing angle on a very flat rear wing? 2% of extra top speed in 2 sectors or 8% more speed in the slow one?

The point is that you can only add that extra wing because you spend time above the trigger speed, able to offset the penalty for carrying it. If you are not above the trigger speed, you are not benefiting from DRD, you are simply carrying more wing, and accelerating more slowly.

The reason it would work extremely well at the old hockenheim is because the fastest corner you would not want it open in is very slow (the entry to the stadium), and hence you could gain benefit from DRD for huge amounts of the straight. Because the DRD would be open for huge amounts of the straight you could carry lots of extra wing. At spa though, you don't benefit for most of the straights. Because of that, you can't carry significant extra wing, because it will penalize you all the way up the straights by accelerating that much slower.

[turbof1]

The point was actually how much time you spend on the slower acceleration and on much on the top speed or near it.

I seriously doubt drd is inmediately slower. I don't believe that. When you add drd to a certain angle set up, the car will be faster. You just add angle to the wing until the top speed is back the same to the original one. It isn't like you suddenly run monaco wings.

And like I said before, you can always take the corner that determines the drd speed slower, which would also allow you to lower the drd cut off point. I think that is a very viable solution. Pouhon is the only corner in that range. All other corners are either fast enough to allow stalling or too slow to make an impact on acceleration.

[beelsebob]

The point was actually how much time you spend on the slower acceleration and on much on the top speed or near it.

Correct – that is, the ratio of the proportion of time above the trigger speed to the proportion of time below the trigger speed. This is in turn monotonically increasing with the percentage of time you spend above the trigger speed.

I seriously doubt drd is inmediately slower. I don't believe that. When you add to a certain angle set up, the car will be faster. You just add angle to the wing until the top speed is back the same to the original one.

False, this will make you slower down the straight, despite hitting the same top seed, because of your slower acceleration with the bigger wing on. Again, DRD does not work while you are accelerating to the trigger speed. This is the key differentiator between it and DRS/f-duct/any other driver controlled device.

While we're at it, no one is asserting that DRD will make you slower. The assertion is that Spa is one of the tracks where you will get very little benefit from it, compared to some other tracks.

The teams have so far not decided that they get enough benefit at any circuit, even the ones where you spend 2-3 times longer above the trigger speed (as a proportion of the lap) than at Spa. They have up until now considered that they can get more benefit out of spending the time they would spend setting up the DRD doing something else. As at spa, they can get less benefit out of the DRD than they have done at other tracks, I highly doubt that any of them will run it.

[turbof1]

False, this will make you slower down the straight, despite hitting the same top seed, because of your slower acceleration with the bigger wing on. Again, DRD does not work while you are accelerating to the trigger speed.

I misunderstood you sorry, I thought you were pointing at the top speed. Acceleration will be a bit lower yes. That disadvantage depends on how much time is spend on acceleration between the speed that drag plays a big role and the drd cut off point. If you spend most of your time outside that window, that disadvantage is rather small. If they spend more time there, it is a bigger disadvantage. At Spa you spend either alot of time at top speed or well beneath it. Anyway not the point either, that got derailed. The point was to give you an example why your model is too simplistic. Don't ask me, ask Lotus, who used drd during the british gp while they could use drd 21%. 6% less then in spa, if we take your model for granted.

You know as well as me that we are talking in hypothetical terms. The big assumption here is it works predictable. The reason why teams dont run it is because they are having big issues to get it to work predictable.

[beelsebob]

False, this will make you slower down the straight, despite hitting the same top seed, because of your slower acceleration with the bigger wing on. Again, DRD does not work while you are accelerating to the trigger speed.

I misunderstood you sorry, I thought you were pointing at the top speed. Acceleration will be a bit lower yes. That disadvantage depends on how much time is spend on acceleration between the speed that drag plays a big role and the drd cut off point.

Correct – or, another way of putting it... That disadvantage depends on what proportion of time you spend above the drd cut off point .

If you spend most of your time outside that window, that disadvantage is rather small.

Yes, and at Spa, the disadvantage is rather large, because you spend a lot of time below the cut off point.

If they spend more time there, it is a bigger disadvantage. At Spa you spend either alot of time at top speed or well beneath it.

Actually, at Spa, you spend a lot of time not very much below it, because most of the circuit is medium to high speed. The amount of time you spend above the trigger point is only 27% of the lap. The amount of time you spend below 130km/h is only 9% of the lap. The rest of the lap (a whole 64% of it) is spent above 130km/h but below the trigger speed, paying a drag penalty for carrying extra wing, but not gaining anything from the DRD.

Between that remaining 64% of the time when you're paying a drag penalty, 71% of the time (or 45% of the total lap) is spent accelerating. Not good at all.

[turbof1]

I think the issue is getting about how much the acceleration penalty is. You'll say alot, I will say not so much. I agree to disagree, you agree to disagree. It is safe to say not one of us wants to spend another full page on at this hour .

Was learnful though. Nice to have such an in debt discussion about drd. Just so you know, drag isn't lineair. You shouldn't take into the account the acceleration below a certain speed (please no discussion at what point that is). I feel thay should be omitted too. Hence why I talked about a window and not just about the spezd above the drd cut off point.

[beelsebob]

I think the issue is getting about how much the acceleration penalty is. You'll say alot, I will say not so much. I agree to disagree, you agree to disagree. It is safe to say not one of us wants to spend another full page on at this hour .

No, it doesn't matter how much the acceleration penalty is. The point is that that penalty is the same whether we're at spa or melbourne. At melbourne we pay that penalty for a short amount of time, at spa we pay it for a long amount of time.

Again, the assertion is not "DRD has no benefit at Spa" the assertion is "DRD has less benefit at Spa than at Melbourne (and almost all other tracks)".

Just so you know, drag isn't linear.

No, it's quadratic with speed – hence why I discussed acceleration while over 130km/h, but below the cut off point, where the drag penalty is significant.

You shouldn't take into the account the acceleration below a certain speed (please no discussion at what point that is).

That's why I didn't, though I admit the speed I chose was somewhat arbitrary.

[SiLo]

You seem to forget that they can only open the DRS in two places now? Which means having DRD would be hugely beneficial for all of those other straights and high speed areas that you used to be able to use it on, and now can't. Hence, the best tracks to use it on are tracks where you used to use DRS the MOST in qualifying.

[beelsebob]

You seem to forget that they can only open the DRS in two places now? Which means having DRD would be hugely beneficial for all of those other straights and high speed areas that you used to be able to use it on, and now can't. Hence, the best tracks to use it on are tracks where you used to use DRS the MOST in qualifying.

Again, no. You are forgetting that DRD can not be opened at all the places that DRS or an F-duct can be.

At spa, the number of places where you can not open DRS, but you can open DRD is extremely small, due to the trigger speed being so high. In fact, the proportion of the lap where DRS is not open, but DRD could be is only 4% of the entire lap! That in fact makes Spa almost as bad as Monaco in terms of DRD's effectiveness.

[raymondu999]

DRD benefits are proportional, not to how amount of straights, nor the time you would have opened DRS in years past.

Hear ye, hear ye-
The DRD benefit, on each track layout, is proportional to the percentage of time you spend around a lap at a speed faster than the trigger speed. And the trigger speed has to be set just above your highest grip-limited speed.

So, first you have to determine your trigger speed, aka "highest grip-limited speed." The higher this speed is, then advantage goes down - otherwise you'd just be making yourself spin. Once you know that number, then you need to look at how long you're at speeds higher than said trigger speed, because the device only helps you while:

Trigger speed < x < terminal velocity

Where x is your car speed. In other words, the DRD advantage is proportional to the amount of time spent between your trigger and your terminal speeds