Raising the front suspesion STILL gives you higher top speed

[xSNAKEx]

I tried this and it raises your top speed by over 10kph depending on the car. Having the front raised should act like a scoop and increase wind resistance. It doesnt.

I think the mistake PD are making here is that raising the front correctly reduces down-force on the front wheels, and so the physics works out less downforce = less drag FULL STOP. Doesn't work that way. Lift can increase wind resitance! Dammit PD cant you get the basics right!

Thats why this happens, and yet to see it in GT

 

[g0ld]

You're right. But at the same time lifting the front in a RWD car increases weight over the drive wheels which technically gives more traction. I've tested at very high speeds, but I haven't seen this 10 kph difference you talk about. The only cars that benefitted from it were cars that were already rear heavy (such as MR cars) or cars that had a bit of default downforce in the back, and even then the gain was minimal (1-2 kph max).

 

[xSNAKEx]

You're right. But at the same time lifting the front in a RWD car increases weight over the drive wheels which technically gives more traction. I've tested at very high speeds, but I haven't seen this 10 kph difference you talk about. The only cars that benefitted from it were cars that were already rear heavy (such as MR cars) or cars that had a bit of default downforce in the back, and even then the gain was minimal (1-2 kph max).

err traction is not the problem for going faster in top speed runs so I dont get your first point at all.

I tested it on a veyron 472kph normally and then I raised the front and got 481.

 

[dj-smurph]

What happens when you raise the front and rear? Is thr increase greater?

 

[xSNAKEx]

What happens when you raise the front and rear? Is thr increase greater?

Thats what I originally meant. I raise the front and drop the rear just like you could in gt5 and it made cars fly in top speed. The car cant turn but it does go faster. Try it out on route x. Its a joke.

 

[Exorcet]

I think the mistake PD are making here is that raising the front correctly reduces down-force on the front wheels, and so the physics works out less downforce = less drag FULL STOP. Doesn't work that way. Lift can increase wind resitance! Dammit PD cant you get the basics right!

It's not so much about induced drag from lift, as the car might not be making that much anyway. Raising the height of the car provides less shielding for the wheels and can impact the underbody drag depending on what's there.

One issue though is ride height itself. Do we still not have the actual ride height? If we do have the ride height does it account for things such as rake of the underbody and low hanging chins, etc?

It could be that even with the front higher, the body still maintains a proper rake. Still in the general case you are right, and less height should probably lead to more speed.

Try testing overall height vs speed and see if you get a faster car with high front and rear instead of low front and rear.

 

[eran0004]

I think the mistake PD are making here is that raising the front correctly reduces down-force on the front wheels, and so the physics works out less downforce = less drag FULL STOP. Doesn't work that way. Lift can increase wind resitance! Dammit PD cant you get the basics right!

More lift = more drag, but less downforce = less drag. If you reduce the overall aerodynamic forces acting vertically on the car, you get less drag.

Here's a simple thought experiment:

Car #1:

Let's say you have a bodywork that at a certain speed is producing +10 lift and -5 lift (it's a complex shape), and you have a wing that produces -10 lift (i.e. +10 downforce). For each lift value, regardless if it's positive or negative, you also get +1 drag value.

That gives us a total of -5 lift (10 - 5 -10 = -5) and +25 drag (10 + 5 + 10 = 25).

Let's then say that we change the angle of the entire vehicle slightly, so that so all lift values are raised by 10%. The bodywork is then producing +11 lift, -4.5 lift and a total of +15.5 drag, while the wing is producing -9 lift and +9 drag.

That gives us a total of -2.5 lift and +24.5 drag.

As a result you lost a lot of negative lift while getting a little bit less drag = higher top speed and a more dangerous ride.


Car #2:

Bodywork is producing +5 lift, -7 lift and +12 drag (still a complex shape, but more streamlined, and the bodywork is designed to generate downforce). A small wing is producing -2 lift and +2 drag.

Sum: -4 lift and +14 drag.

Angle is changed and all lift values are raised by 10%.

Bodywork is producing +5.5 lift, -6.3 lift and +11.8 drag. Wing is producing -1.8 lift and +1.8 drag.

Sum: -2.6 lift and +13.6 drag.

The result in this case is the same: The car lost a lot of negative lift, but also got a little bit less drag.


In this simple model it works, but it comes at an expensive cost: You lose a lot more downforce than drag, and the suspension settings probably contributes to making the handling even worse. In real life you'd be daft to even try this, as it's a lot more effective just to simply remove any wings instead of attempting to change their angle by adjusting ride height.


What's interesting to test, is if a higher rear suspension contributes to higher downforce? And if so, is it worth it, or does the higher rear ride hight worsen the handling more than the added downforce improves it?

 

[RSnider]

It's not so much about induced drag from lift, as the car might not be making that much anyway. Raising the height of the car provides less shielding for the wheels and can impact the underbody drag depending on what's there.

One issue though is ride height itself. Do we still not have the actual ride height? If we do have the ride height does it account for things such as rake of the underbody and low hanging chins, etc?

It could be that even with the front higher, the body still maintains a proper rake. Still in the general case you are right, and less height should probably lead to more speed.

Try testing overall height vs speed and see if you get a faster car with high front and rear instead of low front and rear.

No, still no accurate representation of ride height. I remember tinkering with the Honda Fit and the ride height in the suspension tab was listed as 80 inches or some absurd amount. I can't wrap my head around how PD manages to make such idiotic mistakes game after game.

 

[xSNAKEx]

More lift = more drag, but less downforce = less drag. If you reduce the overall aerodynamic forces acting vertically on the car, you get less drag.

Here's a simple thought experiment:

Car #1:

Let's say you have a bodywork that at a certain speed is producing +10 lift and -5 lift (it's a complex shape), and you have a wing that produces -10 lift (i.e. +10 downforce). For each lift value, regardless if it's positive or negative, you also get +1 drag value.

That gives us a total of -5 lift (10 - 5 -10 = -5) and +25 drag (10 + 5 + 10 = 25).

Let's then say that we change the angle of the entire vehicle slightly, so that so all lift values are raised by 10%. The bodywork is then producing +11 lift, -4.5 lift and a total of +15.5 drag, while the wing is producing -9 lift and +9 drag.

That gives us a total of -2.5 lift and +24.5 drag.

As a result you lost a lot of negative lift while getting a little bit less drag = higher top speed and a more dangerous ride.


Car #2:

Bodywork is producing +5 lift, -7 lift and +12 drag (still a complex shape, but more streamlined, and the bodywork is designed to generate downforce). A small wing is producing -2 lift and +2 drag.

Sum: -4 lift and +14 drag.

Angle is changed and all lift values are raised by 10%.

Bodywork is producing +5.5 lift, -6.3 lift and +11.8 drag. Wing is producing -1.8 lift and +1.8 drag.

Sum: -2.6 lift and +13.6 drag.

The result in this case is the same: The car lost a lot of negative lift, but also got a little bit less drag.


In this simple model it works, but it comes at an expensive cost: You lose a lot more downforce than drag, and the suspension settings probably contributes to making the handling even worse. In real life you'd be daft to even try this, as it's a lot more effective just to simply remove any wings instead of attempting to change their angle by adjusting ride height.


What's interesting to test, is if a higher rear suspension contributes to higher downforce? And if so, is it worth it, or does the higher rear ride hight worsen the handling more than the added downforce improves it?

I get what your trying to say but its not a tug of war balance type thing the way you describe it where one cancels out there other. The way you can adjust the ride height of some cars in gt6 means you are literally facing the whole underneath surface area of the car to oncoming winds. Literally something 5-10 times the size of the frontal are that would normally be exposed. It would either cause severe drag or cause the car to flip at speeds over 300kph.

The fact neither of this happens in gt6, but in fact your car goes faster, is absurd.

 

[Morphisor]

I did a lot of testing on this particular effect in GT5, it was quite ridiculous, even to the point that adding full ballast to the front on a 'trick' setup made it even faster!

Haven't done any testing on this in GT6, what with route X not having full testing set anymore. Was also kind of assuming the new model fixed it...

 

[Stotty]

Ride height in GT6 is like GT5 before they patched it... it's either transposed (ie; front ride height = rear ride height) or there's a major bug in the physics model.

Either way, cars running high front and low rear have more rotation/less understeer... see current Integrale TT and Tsukua.

Something else for PD to fix

 

[mistersafeway]

No, still no accurate representation of ride height. I remember tinkering with the Honda Fit and the ride height in the suspension tab was listed as 80 inches or some absurd amount. I can't wrap my head around how PD manages to make such idiotic mistakes game after game.

It's milimetres, blame the localisation.

 

[Nuschel01]

It already was like this in GT4, I made 540kph in the Minolta-Toyota with a raised front-end...

 

[xSNAKEx]

It already was like this in GT4, I made 540kph in the Minolta-Toyota with a raised front-end...

PD love to re use stuff from old games dont they. I bet this "bug" is from gt1. Actually its game braking unless you drive with no tuning allowed.

 

[rams1de]

Ride height in GT6 is like GT5 before they patched it... it's either transposed (ie; front ride height = rear ride height) or there's a major bug in the physics model.

Either way, cars running high front and low rear have more rotation/less understeer... see current Integrale TT and Tsukua.

Something else for PD to fix

Did they ever get round to fixing it in GT5? I thought they just disabled the effect of ride height. Certainly for a while many people weren't bothering with it and leaving settings 0|0

 

[eran0004]

I get what your trying to say but its not a tug of war balance type thing the way you describe it where one cancels out there other. The way you can adjust the ride height of some cars in gt6 means you are literally facing the whole underneath surface area of the car to oncoming winds. Literally something 5-10 times the size of the frontal are that would normally be exposed. It would either cause severe drag or cause the car to flip at speeds over 300kph.

The fact neither of this happens in gt6, but in fact your car goes faster, is absurd.

Flying doesn't happen because wind pushes underneath object, it happens because wind causes pressure drop on top of the object. If the forces created by the drop in pressure in greater than the force of gravity acting on the object, it will fly. Hovercrafts however flies because they create an air cushion underneath the body, but they need skirts to be able to trap the air inside, or else it would easily escape and the hovercraft would be grounded. So unless you're fitting your car with skirts to prevent the air from escaping from underneath the car, simply driving nose-up would not be enough to make it fly.

Unless the car has some serious design flaws, as in the case of the Mercedes CLR.

 

[RufusGonePunk]

Flying doesn't happen because wind pushes underneath object, it happens because wind causes pressure drop on top of the object. If the forces created by the drop in pressure in greater than the force of gravity acting on the object, it will fly. Hovercrafts however flies because they create an air cushion underneath the body, but they need skirts to be able to trap the air inside, or else it would easily escape and the hovercraft would be grounded. So unless you're fitting your car with skirts to prevent the air from escaping from underneath the car, simply driving nose-up would not be enough to make it fly.

Unless the car has some serious design flaws, as in the case of the Mercedes CLR.

Slightly off topic, but it also happened to the 911 GT1 and the V12 LMR:





Caused by the rapid change in pressure when cresting the hill behind another car. So strong that it sucked Bill Auberlen's visor open before he took off. Many times more than could be created just by running a lot of negative rake.

 

[trustjab]

It is a rule flaw. People confuse it with a design flaw, but the design is to a ruleset made by the FIA/ACO.

 

[Exorcet]

Flying doesn't happen because wind pushes underneath object,

That's part of it actually. You don't need skirts to trap high pressure air to create lift.

It's the Angle of Attack that matters. When the floor is exposed to incoming air, it begins to generate lift. The top of the car also generates lift. It's easy to generate enough force to lift off the ground at speed.

What also helps to flip the car is that more lift is lost in front than the rear when the car is drafting.

 

[JEMcG]

err traction is not the problem for going faster in top speed runs so I dont get your first point at all.

I tested it on a veyron 472kph normally and then I raised the front and got 481.

No one cares about this particular set of car and track combination.

 

[Astro_BS-AS]

No one cares about this particular set of car and track combination.

I think you are wrong about that. It´s not about "this or that car". It´s the physics model. And that applies to ALL cars in game.

 

[JEMcG]

Ok maybe 3 people care.