Physics discussion thread

Unfortunately, this test isn't very good if you look closely.
Unlike in my test where i copied the actual real life wet line, in this test the "wet line" is actually just the dry line for the most part. Let's give it a closer look:
(to avoid confusion: in the following i will use "quatation marks" when talking about the "dry / wet line" in the video and no quation marks when talking about the actual dry / wet line)

-Braking into t1 was different
-Through t1, t2 and t3 the lines were identical
-Braking into t4 different
-Line in t4 identical
-Braking t5 identical
-Line in t5 different
-Braking and line in t7, t8 identical
-Line in t9 identical exept that the car ran wider on the "wet line" so the "wet line" was actually more of a dry line than the "dry line"
-The lines in t10 left me confused because they ran wide and avoided the rubbered line on the "dry line" but kept it tight and on the rubber on the "wet line". So it is the wrong way around. The "wet line" was the dry line and the "dry line" was the wet line
-In t12 the lines were pretty identical exept that, again, they ran wider on the "wet line" than on "dry line". Once again taking a more dry line approach on the "wet line" than on the "dry line"
-In t13 it was basically the same as t12. Lines very similar exept that on the "wet line" they actually hit the apex more. Once again, taking more of a dry line than in the "dry line"
-And finally in t14, the lines were different.

Overall, you can see that the test did a pretty bad job at taking the intended line with the "wet line" being more of a dry line than the "dry line" in t9, t10, t12 and t13.


So where does the difference in lap time come from?

Firstly, you can see on the dasboard that in the "dry line" the tires are not up to pressure and temparature yet. But in the "wet line" they are in the perfect window. JUST THIS ALONE makes the entire test completly worthless. The conditions are clearly not identical for both laps. Tire pressure makes a huge difference in ams2. Also the fuel was higher on the "dry line" than on the wet line. Presumably they just set one "dry line" lap with cold and underpressured tires, then switched to the "wet line" once the tires were in the window.

Secondly, it immediately becomes quite clear that the "wet line" just simply extracted more lap time by pushing harder and simply driving better.
Just taking a look at t9. Despite taking a similat line, the minimum speed on the "wet line" was 150 and on the "dry line" it was 142, simply pushing harder on the "wet line". Same thing in t12. Similar line but 93 min speed on the "wet line" and 87 min speed on the "dry line". Again the same thing in t13: same line but doing 161 on the "wet line" and 153 on the dry line.

So in conclusion the test:
-Didn't even take the wet line
-Didn't have identical conditions
-Simply drove bad on the "dry line"

Can i proof that the "dry line" was a really bad lap?
Absolutely.
I just jumped in and did a lap in the LMP2 G2 in wet conditions with heavy rubber preset using the dry line, completely ignoring the rubber and even with a very messy lap, i instantly beat both the "dry line" and the "wet line" lap time in the video.

With a bit of practice you could easily do a 1:45 in these conditions. Since the lap times in the test are not competitive, it doesn't say much anyways.

In my original test i put in lots of attention to detail to ensure it is a fair as possible (such as waiting in the pits with a stop watch to ensure the rain falling onto the track in both sessions is identical). You'll also find that, unlike in this test, the lap times in my test were actually competitive.

Unfortunately, this test wasn't representative and as you could see, you can go much quicker on the dry line.
Really hoping the rubbered line will become much more slippery in the future, so that the wet line will actually be faster. For the moment the dry line in the wet is still the way to go.

 

Completely agree.
I just have a doubt,since in the past the weather progression and water accumulation was a bit "unclear".
I don't have the time to test it today,but what if in this condition there is just "not enough water" on the track yet (i am talking physically, not visually)?
I want yo run the same test,just setting as you did real time and 1 weather slot.
And then trying to set 2 identical time slots and setting weather acceleration to x60....just to see if there is any differences

 

Not saying I disagree with a lot of this what you wrote, but couple of points.

1) Kerbs don't get slippery on wet on AMS2, this is known limitation currently and will surely impact what lines you want to take and where. I suspect the driver was using the wet line in place it felt it gave better grip and performance and dry line in places where it made sense with the available grip, kerbs and handling characteristics of the car otherwise.

2) It's a lot easier to push if there is more grip, so saying "didn't push as much" doesn't mean much, you cannot know where and how the driver felt the grip limit.

In any case, I suspect you are right that there is not enough difference for it to be impactful enough compared to how it can be IRL. Like I wrote already earlier, sometimes it's the AI calibration challenges that force them to be more conservative on things like this. Other thing where I similar style of issues (being conservative) is tire wear and it's impact.

Anyway, I appreciate the effort and detail from you on this subject. iRacing from what I have seen, is clearly a benchmark on this wet weather stuff currently, but at least on AMS2 there is a lot of dynamics available (and it's not like they didn't spend years on iRacing to make it).