Answer to GT5's slipstream issues

E

Energizerrr

(Banned)
1,115
Hi, I am aware that there's already a thread regarding this but I'm talking about something different here.

Some people say drafting effect in GT5 is too drastic and unrealistic to which I disagree, the actual slipstream is very realistic BUT, what isn't realistic is the aerodynamic drag which isn't there while you slingshoot out of the draft.
In other words, the actual slipstream is realistic but the slingshoot out of it isn't realistic because there just isn't enough drag present so the car doesn't decelerate enough/keeps the speed gained in the slipstream much longer than it should.

The question which is raised here is why? And the answer is - because GT5 has no wind (!), whole aerodynamics model is based on an equation:
X ammount of downforce at Y speed (hence the wheelie glitch with X2010).


I hope this is the physics fix Kaz said 2.0 will fix.
Cheers.
 
I'm not an expert on it, but when I do slingshot, I actually have to do it at the last moment, when I am on similar cars. If I get out of it early, I lose the speed pretty noticeably.

Also, I thought the whole slipstream talk was about the car accelerating IN the slipstream too fast, not slinging out.

As for wind, there has to be, unless the wind noise we're hearing isn't really wind.
 
I did a test a while back on aerodynamic drag in GT5. I took a bunch of Le Mans cars out to the long straight on the final sector at Nordschleife and recorded top speeds at different aerodynamic settings. If I remember right there was only a 3 MPH difference between the lowest possible aero settings and the highest possible settings, and this is using Le Mans aero kits.
 
Zilla
I did a test a while back on aerodynamic drag in GT5. I took a bunch of Le Mans cars out to the long straight on the final sector at Nordschleife and recorded top speeds at different aerodynamic settings. If I remember right there was only a 3 MPH difference between the lowest possible aero settings and the highest possible settings, and this is using Le Mans aero kits.
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Have you tested any of the F1s? I remember in GT4, the aerodynamic on the F1 was much more dramatic than that. Increasing the aerodynamics on it really decreased the top speed from what I remember.
 
daus26
I'm not an expert on it, but when I do slingshot, I actually have to do it at the last moment, when I am on similar cars. If I get out of it early, I lose the speed pretty noticeably.

Also, I thought the whole slipstream talk was about the car accelerating IN the slipstream too fast, not slinging out.

As for wind, there has to be, unless the wind noise we're hearing isn't really wind.
Click to expand...

It's just an audio sample, there isn't any wind in GT5. :lol:
And as for the speed in the slipstream - well, it's magical to be honest. I'm a passionate bycycle rider and on a straight road (as in no elevation change) I can hit well over 50km/h while slipstreaming a bus or a car (and I have a 16 kilo mountain bike with 8cm thick tires) and the acceleration is immense, normally I can go about 40km/h without slipstream. So, if I experience such a drastic change - imagine a high powered race car doing the same.
 
I disagree with it being 'realistic' - pertaining to the speed boost you get from getting into the slipstream.

And no, i don't race in real life, but it doesn't need a real racing driver to disprove something that is very obvious.

This was in reply to you from another thread:

I'm not an Engineer but based on my collective knowledge throughout the years of being motorsport fan, the slipstream in GT5 is way off compared to real life.

Just to make an example (NASCAR Indianapolis) - This clip shows how hard it is to pass at Indy with 2 pretty even cars. Slip stream had little to no factor. Starting at 2:30 - Mark Martin was about
2-4 car lengths behind Jimmie Johnson. That went on til' the last lap. Martin never made the pass.



About the speed: IRL, these cars reach Turn 1 in qualifying trim at around 200-205 mph. This would be a tad slower in Race Trim and about the same with the draft.

Now in GT5: I've had my share of racing at Indy online with NASCARS and it is just pure mayhem when it comes to the speed we reach before commencing braking. If you exit off a turn coming into a long
straight at around 160-170, expect to see your speed reach 230+ with a car infront of you towing you along into the next turn. I find this ridiculously absurd (and laughable playing demolition derby online). By the
way, regardless of the tires you use, you will still have the same effect. In regards to the realism of the tires, here's an independent test i made prior to the release of GT5 (click here).

Furthermore, being an online series admin, i personally have a lot of experience pertaining to the draft. It's always been a complaint from all of the participants, especially when we go to draft happy tracks
such as Monza and Le Mans. It affects the dynamics of the race as a whole. If you lose the tow of the draft, then goodbye to you. Likewise, if you are leading and you are alone and turning the fastest and most
consistent laps all day, 2 drivers in tandem from 10 seconds back can tag along and catch you within a few laps.

F.I.N.
Click to expand...
 
Energizerrr
It's just an audio sample, there isn't any wind in GT5. :lol:
And as for the speed in the slipstream - well, it's magical to be honest. I'm a passionate bycycle rider and on a straight road (as in no elevation change) I can hit well over 50km/h while slipstreaming a bus or a car (and I have a 16 kilo mountain bike with 8cm thick tires) and the acceleration is immense, normally I can go about 40km/h without slipstream. So, if I experience such a drastic change - imagine a high powered race car doing the same.
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Hmm, saying there's no wind is almost like saying there's no air though. I know for sure GT5 has air, as sometimes some of the grass moves when a car passes by.

Wind is really more like a variable, as there can be many different wind speeds. However, I think there's some merit to when you say that the aero may simply be calculated by x amount of downforce, to y amount of speed.
 
I am not to sure if slipstream is right or wrong to be honest.

I think what we have now is actually a combination of slipstream and GT's boast function at work. We all know boast is there and my betting is that the game gives you a speed boast to help you catchup to the car infront. You then hit the slipstream which gives you another speed gain and before you know it, you hurtle past with a 20 to 30kph advantage.

Same thing happens in the NASCAR Daytona race when you are the one being chased down as the car directly behind has a slight advantage over you but it always seems to be a car further back thats the one doing a roadrunner act.

The whole thing could be made even more exaggerated if a double slipstream is in play.

It would be interesting to find out if GT gave us an option to turn off boast
 
xxDingerxx
I am not to sure if slipstream is right or wrong to be honest.

I think what we have now is actually a combination of slipstream and GT's boast function at work. We all know boast is there and my betting is that the game gives you a speed boast to help you catchup to the car infront. You then hit the slipstream which gives you another speed gain and before you know it, you hurtle past with a 20 to 30kph advantage.

Same thing happens in the NASCAR Daytona race when you are the one being chased down as the car directly behind has a slight advantage over you but it always seems to be a car further back thats the one doing a roadrunner act.

The whole thing could be made even more exaggerated if a double slipstream is in play.

It would be interesting to find out if GT gave us an option to turn off boast
Click to expand...

You probably mean "boost."

Well, in GT5P, there was an online event where there was specifically no "boost." It was mentioned that the slipstream was still seeming exaggerated to many. In GT5, I "think" the races in extreme have no "boost" if I'm correct, and the slipstream is just the same as to if there is one.

Also, in online events, there is an option to turn it off. *edit by online events, I mean online rooms/lobbies with friends and other people.
 
If slipstream was not overly exaggerated, why did PD turn it off for online qualifying?

I really don't think this is debatable. If you do not believe the speed boost is unrealistic, you're being intentionally obtuse.
 
Zilla
If I remember right there was only a 3 MPH difference between the lowest possible aero settings and the highest possible settings, and this is using Le Mans aero kits.
Click to expand...
Was the top speed limited by gearing or by aerodynamic drag? The low drag aero setup doesn't make any difference if you're already hitting the redline with the high drag setup.

I conducted a test of my own, with a stock 908 HDi on the Hunaudieres straight without chicanes, the gearing being so tall that the theoretical top speed was 493 km/h to make sure there won't be any redlining. With the lowest possible aero setup the car reached 374 km/h well before where the last chicane would have been and continued with the same speed to (and beyond) the Mulsanne kink. With the highest possible aero setup it reached 357 km/h just before the kink and lost a few km/h in the following uphill.

That's a difference of 17 km/h, 10 or 11 mph depending of the unseen decimals. The difference equals 4,77% of the 357 km/h figure and as drag increases in the square of speed it means the high drag setup has around 10% more drag than the low drag setup. Definitely a difference that can't be swept aside as being non-existant or meaningless.
 
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Don't think theirs a tide either, at Monaco.

I thought the rubber banding was well documented.
 
After watching the Bathurst 1000 yesterday it's painfully easy to see how strong the draft is in GT5. If the draft was realistic those V8 Supercars would have passed half way through the Conrod Straight.
 
Yeah, I mean't boost. Lack of sleep because of going to bed late and getting up early for the GP is starting to fry my brain:-)

The reason why I think boost is the problem is I cannot think of a single race online with boost off where I have seen this exaggerated effect in action (not saying it doesn't, just that I haven't seen it).

Other reason is there have been plenty of times offline when I have been in prime position for a slipstream, yet I can barely get side by side. Same race though, same straight from a little further back and bam, I go sailing past.

That said, it could be down to setups. Low wing, higher gear ratio, even tire compounds and wear (speed difference on a corner exit) can all have an effect on the level of slipstream achieved.
 
daus26
Have you tested any of the F1s? I remember in GT4, the aerodynamic on the F1 was much more dramatic than that. Increasing the aerodynamics on it really decreased the top speed from what I remember.
Click to expand...


No, I haven't, but do I have plans to record some times in the F10 around the 24H Ring to post in the F1 24H thread, so I'll check it out when I do that.


Greycap
Was the top speed limited by gearing or by aerodynamic drag? The low drag aero setup doesn't make any difference if you're already hitting the redline with the high drag setup.
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Of course I accounted for the rev. limiter. :)
 
I'm enjoying the comments that assume that because there are things like downforce, moving grass, or wind sounds, that "air" is applied in the physics of the game.

I'm not trying to cut anyone down but come on...

It's like this; PD didn't just code up the effects of air and suddenly all these other effects appeared. This is a game, sound effects, physics modelling, animation, etc... it's all separate. There are no general laws of physics in the game. If there were, despite how difficult it would be to cover them all properly, they would then simply need to add the cars in with the proper variables such as weight, size, power, materials, etc. But because that's not done, everything has to be done individually. Yes, you can copy-paste stats from one car to the next but if it handles different, that means they had to change stuff.

I don't know any kind of coding, and barely know anything about how games are made, but seriously. Games are not like real life yet. If you see something that acts real, it's because it was programed to act like that. No game company programs everything into their game, it's impossible and even if it were possible, there's no point.
 
Negrumir
I'm enjoying the comments that assume that because there are things like downforce, moving grass, or wind sounds, that "air" is applied in the physics of the game.

I'm not trying to cut anyone down but come on...

It's like this; PD didn't just code up the effects of air and suddenly all these other effects appeared. This is a game, sound effects, physics modelling, animation, etc... it's all separate. There are no general laws of physics in the game. If there were, despite how difficult it would be to cover them all properly, they would then simply need to add the cars in with the proper variables such as weight, size, power, materials, etc. But because that's not done, everything has to be done individually. Yes, you can copy-paste stats from one car to the next but if it handles different, that means they had to change stuff.

I don't know any kind of coding, and barely know anything about how games are made, but seriously. Games are not like real life yet. If you see something that acts real, it's because it was programed to act like that. No game company programs everything into their game, it's impossible and even if it were possible, there's no point.
Click to expand...

👍
Agreed.
 
Anybody who watches real racing can tell that the slipstream effects in the game are tremendously exaggerated. The draft can be caught from much too far away and the speed boost is much too high. It's almost like we're driving through maple syrup rather than air, and the hole takes longer to close up.

By the way, I'm not a hater. I LOVE Gran Turismo. :D
 
Energizerrr
Hi, I am aware that there's already a thread regarding this but I'm talking about something different here.

Some people say drafting effect in GT5 is too drastic and unrealistic to which I disagree, the actual slipstream is very realistic BUT, what isn't realistic is the aerodynamic drag which isn't there while you slingshoot out of the draft.
Click to expand...
Proof?

Also, it's not realistic at all.

My CFD is below, it goes for multiple pages.

https://www.gtplanet.net/forum/showthread.php?p=5490358#post5490358

The drag coming out of the draft is there. Drag is drag, it isn't going to build up just because you've been drafting.


The question which is raised here is why? And the answer is - because GT5 has no wind (!), whole aerodynamics model is based on an equation:
X ammount of downforce at Y speed (hence the wheelie glitch with X2010).
Click to expand...

That's more than enough. You don't need "wind".

D = .5*rho*CD*A*V*V

L = .5*rho*CL*A*V*V



EDIT

-To simulate a bike drafting off a car, you would need a car drafting off a boat [on wheels?]

-Wind sound is simple audio

-Grass blowing is most likely a simple script not related to aerodynamic simulation at all.


EDIT 2

-If you really want to get technical on the bike drafting example, what was your Reynolds number?

Re = rho*V*x*mu^-1

Extremely unlikely to be the same as a car.
 
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UnkaD
Anybody who watches real racing can tell that the slipstream effects in the game are tremendously exaggerated. The draft can be caught from much too far away and the speed boost is much too high. It's almost like we're driving through maple syrup rather than air, and the hole takes longer to close up.

By the way, I'm not a hater. I LOVE Gran Turismo. :D
Click to expand...

Totally agree with this. Take the Caterham as an example. Take them out round Nurb GP/F with a mate and see just how much slipstream you get from way back.

Makes for exciting racing as you are constantly swapping position but its just like you've got boost switched on
 
Energizerrr
The question which is raised here is why? And the answer is - because GT5 has no wind (!), whole aerodynamics model is based on an equation:
X ammount of downforce at Y speed (hence the wheelie glitch with X2010).


I hope this is the physics fix Kaz said 2.0 will fix.
Cheers.
Click to expand...
GT5 has no wind?!?!??!

Have you ever burned rubber in GT5?






Which car is more stationary as they're spinning their tires? so the wind is obvious.

So the wind comment is wrong.

:) That is WIND if I ever saw it. haha
 
Negrumir
I'm enjoying the comments that assume that because there are things like downforce, moving grass, or wind sounds, that "air" is applied in the physics of the game.

I'm not trying to cut anyone down but come on...

It's like this; PD didn't just code up the effects of air and suddenly all these other effects appeared. This is a game, sound effects, physics modelling, animation, etc... it's all separate. There are no general laws of physics in the game. If there were, despite how difficult it would be to cover them all properly, they would then simply need to add the cars in with the proper variables such as weight, size, power, materials, etc. But because that's not done, everything has to be done individually. Yes, you can copy-paste stats from one car to the next but if it handles different, that means they had to change stuff.

I don't know any kind of coding, and barely know anything about how games are made, but seriously. Games are not like real life yet. If you see something that acts real, it's because it was programed to act like that. No game company programs everything into their game, it's impossible and even if it were possible, there's no point.
Click to expand...

There is no "wind" in gt5 the ps3 lacks the processing power to do cfd on the fly. Hell a room full of superclusters has has trouble modeling fluid dynamics on a car. How is the ps3 going to calculate trailing wake vortex let alone fluid interaction on curved surfaces.
 
another_jakhole
GT5 has no wind?!?!??!

Have you ever burned rubber in GT5?

<a href="http://www.youtube.com/watch?v=3wAxSJUHooM">YouTube Link</a>

<a href="http://www.youtube.com/watch?v=-_9egMN3bKA">YouTube Link</a>

Which car is more stationary as they're spinning their tires? so the wind is obvious.

So the wind comment is wrong.

:) That is WIND if I ever saw it. haha
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No friend, that's just data values.
 
trk29
If there is no wind then why does smoke move, and flags move through the air especially on Nurburgring.
Click to expand...

Because GT5 isn't real life, and the guy that posted it means there's no wind turbulence for cars, aerodynamics, and less drag
 
Energizerrr
Hi, I am aware that there's already a thread regarding this but I'm talking about something different here.

Some people say drafting effect in GT5 is too drastic and unrealistic to which I disagree, the actual slipstream is very realistic BUT, what isn't realistic is the aerodynamic drag which isn't there while you slingshoot out of the draft.
In other words, the actual slipstream is realistic but the slingshoot out of it isn't realistic because there just isn't enough drag present so the car doesn't decelerate enough/keeps the speed gained in the slipstream much longer than it should.

The question which is raised here is why? And the answer is - because GT5 has no wind (!), whole aerodynamics model is based on an equation:
X ammount of downforce at Y speed (hence the wheelie glitch with X2010).

I hope this is the physics fix Kaz said 2.0 will fix.
Cheers.
Click to expand...


I drive Ferrari F1's and I can tell you the slip stream is at least twice as powerful compared to real life , looking at overtakes in f1

The downforce loss behind someone else around corners is fine , I'd say a bit easier but just little bit
 
Cowboys965
Because GT5 isn't real life, and the guy that posted it means there's no wind turbulence for cars, aerodynamics, and less drag
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Exterior damage affects aerodynamics. It may not be comparable to real life, but it doesn't mean it's not there. Progress is made, for GT5 that's what we got.


It's more obvious now that's what the Physics update will include. Was Kaz supposed to say, "14. Improved AI/Physics/Aerodynamics"?
 
another_jakhole
Exterior damage affects aerodynamics. It may not be comparable to real life, but it doesn't mean it's not there. Progress is made, for GT5 that's what we got.

It's more obvious now that's what the Physics update will include. Was Kaz supposed to say, "14. Improved AI/Physics/Aerodynamics"?
Click to expand...

It does????? O.o
 

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