KERS/DRS Implementation & How It Can Be Improved

Discussion in 'Gran Turismo Sport' started by LeGeNd-1, Mar 30, 2019.

  1. omgsean1

    omgsean1

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    I don't think the Bugatti VGT have hybrid modeled in the game yet.
     
  2. Hoopzah

    Hoopzah

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    Well while driving it flashes on the bottom of the screen so something is definitely engaging, but there's no battery meter so idk what it's doing.. it is definitely ahelluva lot faster than it was though. Not the Gr.1 machine, but the actual VGT.
     
  3. Leggacy

    Leggacy

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    The DRS should be a toggle, and close when you brake, it’s a bit awkward to have to constantly press the button.
     
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  4. Voodoovaj

    Voodoovaj

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    Maybe it's me, but I'm pretty sure you guys don't understand what DRS is supposed to do.

    The faster a car goes, the more difficult it is to go fast. Even with the same slippery aero, you need an huge increase in power for a modest increase in speed. DRS isn't supposed to give you a top speed boost, it gives you a drag reduction. So, when you are accelerating out of a corner, you deploy DRS so that there is less drag and, ergo, more uninhibited acceleration down the straight allowing you to pass the other cars.

    This is especially useful with formula cars because having an open wheel configuration is horrendous for drag coefficient.

    @LeGeNd-1 maybe I simply don't quite understand what you have written, but if you have HIGH downforce, there is more drag so deploying DRS should have less effect on the car (as you've stated). If you have reduced all your downforce to make the car as slippery as it can be, and then deploy DRS, you should have a greater net gain, as you have stated. How is that "whack" aero physics?
     
  5. Leggacy

    Leggacy

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    Oops! Removed, wrong thread
     
    Last edited: Apr 11, 2019
  6. LeGeNd-1

    LeGeNd-1 Premium

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    Just tested this, it displays a DRS icon but it's automatically deployed in the straights. You can't manually open/close it. Added it to the first post for completion, thanks :tup:

    DRS helps acceleration by virtue of less drag AND also improves top speed. How is that not understanding how DRS works? In F1 once the car hits its aero limited top speed, if you open the DRS it will gain a few extra km/h. How much km/h exactly depends on the length of the straight and the level of aero at baseline. It's not a speed boost in the sense that you press a KERS/NOS button, but it still makes you go faster.

    In terms of the difference between high and low downforce, well this is the contentious issue. I'm trying to find videos of real life F1 going down a straight without DRS, and again with DRS, at Monza and a suitably twisty track (I'm thinking Hungaroring because Monaco doesn't really have a proper straight), but it's surprisingly difficult. I'm thinking of testing in Assetto to see if there are any difference.

    If you think about Monza, where the cars already run pretty much flat rear wings, then opening that DRS slot isn't going to affect the drag significantly. Compare to the other extreme at Monaco, where the wing angle is higher, opening the DRS will have a much greater reduction in drag. I'm not saying the car at Monaco is going to have a higher top speed than Monza, but the relative speed gain is gonna be more. This is the opposite in GTS. I hope that makes sense.
     
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  7. Voodoovaj

    Voodoovaj

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    I haven't set up a car for down force, much less an F1, but mathematically, I don't believe that your supposition is correct.

    DRS can't have a greater reduction of drag on a high down force car because there's only one element being removed from the equation and to a lesser degree. The fixed elements are still creating high amounts of drag, so the DRS element bears a lower percentage of the total down force created.

    On a low down force set up, like Monza, the DRS element accounts for a higher relative amount of the down force, so when it's removed, the difference in drag should be greater.

    The DRS is only allowed to move a fixed amount (50mm), so if the element is set up for higher down force, it will still provide more down force than it would in a low down force set up, because it's movement is still 50mm relative to it's original position (one being a high down force position, the other being a low down force position). Even if the element were a constant in the two set ups (as in the same original angle), DRS would still have a greater effect in a low down force scenario.

    so hypothetical math. (assuming a 733kg F1 car with fluids, etc, etc, rounded to 800kg)

    (high down force set up) 800kg of car + 3x downforce = a downward force of 3200kg

    (low down force set up) 800kg of car + 2x downforce = a downward force of 2400kg

    Assuming the DRS element is a constant and it adds 200kg to the downward force (I don't know the exact amount DRS adds), that force is a proportionally greater component the low down force set up, so the relative speed gain should be greater. (6% of the down force versus 8%)

    For the DRS deployment to give greater gains in the high down force set up, the DRS would have to account for a greater percentage of the total down force.

    Did I miss something?
     
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  8. LeGeNd-1

    LeGeNd-1 Premium

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    Without being overly authoritative, and keeping in mind my limited expertise in aero knowledge as well, I think using downforce figures to illustrate this is not the best way. Yes downforce is related to drag, but they are not equal and downforce doesn't affect top speed (except for cases where the car lifts dangerously at speed, example CLR at Le Mans). Also a lot of the downforce produced is from the floor/diffuser, which contributes little to drag and needs to be taken out of the equation since DRS doesn't affect it. Secondly, a lot of the drag in open wheelers is from the exposed wheel/cockpit/suspension, which again will be constant no matter what wing setup you use. Even lowering the wings to minimum downforce is only going to reduce the drag by a small amount in the grand scheme of things.

    Taking those factors into account, what we need to look into then is basically just the drag of the front + rear wing. According to wikipedia, the Cd of F1 is around 1.4. If we assume 50% of that is from the wheels/cockpit/suspension, then the front and rear wings produce about 0.7 of drag. Let's say they each contribute 0.35. Then let's say DRS when open reduces rear wing drag by 50% (eyeballing the size of the slot compared to the height of the rear wing roughly is half). Low downforce setup has roughly 75% of the drag of high downforce (middle ground between DRS open/closed).

    Then hypothetical math:

    HDF
    DRS closed = F 0.35 + R 0.35 = 0.70 Cd
    DRS open = F 0.35 + R 0.175 = 0.525 Cd
    Difference = 0.175 Cd (25% from baseline)

    LDF
    DRS closed = F 0.26 + R 0.26 = 0.52 Cd
    DRS open = F 0.26 + R 0.175 = 0.435 Cd
    Difference = 0.085 Cd (16% from baseline)

    Of course, this is all just back of paper calculations and Adrian Newey will probably laugh at it. But that's how things stand in my mind anyway.


    BTW, I also did a test in Assetto Corsa. Using the SF70-H at a top speed test track mod with 3km long flat straight:
    HDF - 305 kmh (DRS closed), 312 kmh (DRS open), difference 7 kmh
    LDF - 335 kmh (DRS closed), 340 kmh (DRS open), difference 5 kmh
    So not as dramatic difference as GTS, but LDF has smaller difference (as per my hypothesis).

    Gearing can't be adjusted in AC unfortunately, but they both sit at roughly 12,000 rpm (HDF at 7th gear, LDF at 8th gear) at top speed so we can assume the car produces the same power. Also used manual full battery boost in both cases (the deployment profile doesn't give equal boost at 7th and 8th otherwise).
     
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  9. Hoopzah

    Hoopzah

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    I would have to disagree and state that, for all intent and purpose of this discussion, down force IS affectively drag. Also, the more down force a vehicle produces the lower it's top speed effectively becomes.. as one is essentially inducing drag to combat lift. It's through another axis yes, but it's still considered drag.
     
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  10. LeGeNd-1

    LeGeNd-1 Premium

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    Well for the purposes of this discussion you can simplify because F1 cars generate most downforce from upper body wings (discounting underbody downforce and drag from exposed wheels/cockpit like I said). But when you get to fan cars (2J, Brabham BT46, RB X1) then their drag is going to be smaller than what total downforce they can produce, so the simplification is going to be inaccurate. Their downforce isn't going to affect top speed either (unless you count the fan robbing the engine of a few extra horsepower). Anyway, since there are no fan cars in GTS at the moment we can still use the simplification (though I prefer not to, just for accuracy reasons).
     
  11. Hoopzah

    Hoopzah

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    Ok then to keep it simple:
    Drag is a natural reaction to the production of down-force.
    Drag absolutely, positively, and unequivocally effects the top speed of any vehicle. Be it a fighter jet, formula car, family sedan, roller skates, you name it.
    The coefficient may change but as long as it exists, there will be a positive or negative reaction.. that's just physics.
     
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  12. Scuderia Paul

    Scuderia Paul

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    The GT-R LM Nismo was designed around the idea of taking the 'flow through' concept to another level. It wasn't just so they could have an FWD car. After the engine the floor opened into a pair of enormous venturi tunnels which created huge downforce with low drag. Putting an engine in the middle would have reduced the tunnel size to the point it would be pointless.

    It was a case of they thought the pros outweighed the cons. Nissan said they expected to lose ~5s in the corners but gain ~10s on the straights at Circuit de la Sarthe.

    I have a soft spot for the GT-R LM Nismo. While it was an unmitigated disaster, part of me likes that it exists and that a company tried such a high profile experiment in this day and age. Having said that, there will always be part of me that thinks why didn't they make a conventional LMP1-H. They would possibly still be in WEC if they had.
     
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  13. Hoopzah

    Hoopzah

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    Interesting idea.
    The brass must have already decided amongst themselves that if it didn't work, they were going to pull the plug on WEC. That was such an embarrassing race for Nissan, they had no choice really.
     
  14. LeGeNd-1

    LeGeNd-1 Premium

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    So they've added DRS for the Subaru IOM TT car and McLaren VGT (Gr.X only). Subaru I can understand, but the McLaren doesn't even have movable wings so how does DRS even work? :odd: I notice it has moving diffuser flaps, but it's not affected by pressing the DRS button.