Airbrakes on the Nissan R89C

[Ten]

I can see both of your points, and I understand them fully. I don't know a lot about cars, so all my downforce tuning and driving ability in GT has always centered around my knowledge of physics.

I wouldn't say the nose of the car dipping is LAW, but it may as well be. Unless your car has no suspension and just rides on a solid frame that does not give, the weight transfer to the front end will indeed cause it to dip.

I run into a problem I call the rubberband effect when diving into a corner in a high-powered car. I'll brake hard while cutting the wheel in the direction of the turn, and usually understeer for the entire duration of the braking. Then, slowly easing the wheels back into a centered position, I use the power-over tactic and gun the accelerator, causing the nose to rise, the rear to dip, and the entire car to tilt to the opposite direction of the turn. My rear wheels (assuming I'm in a 4WD, which I almost always am) will hold traction better as the engine feeds the power back to the rear wheels, aided by the weight transfer of abrupt acceleration. My front wheels, moreso the inside one, will lose traction, and I'll find myself pumping the accelerator, shifting weight in a back and forth motion. This is sloppy, I know, but it more times than not saves me from my own stupidity when I dive recklessly into a turn at the top of 4th gear.

This displays both points in action - can we not agree that you are both right? Who really gains from the two of you presenting your point over and over, in a competitive manner?

 

[Hyundai Racer]

and thats not physics, its mechanics.

Mechanics, if you don't know is a part or physics.

 

[superlemon]

just cuz u brake a mass doesnt make the front dip.

I know but the weight transfer of a car braking will compress the front suspension.

Initially the brakes work on the wheels only. This transfers energy via the suspension to the car itself.

As far as cars with suspension go, a forward weight transfer when braking is a law. I doubt anyone can think of a real life counter-example.

Also you said that shifting weight forwards is a more efficient way to brake, which is clearly wrong.

Don't over-complicate your argument. We are talking about cars as we know them. A bike is a simpler illustration of this theory. Since when have you pulled a wheelie by braking too hard on your bike for example ?

 

[jr93alty]

i never said u would pull a wheelie. i just said the mass would try to go underneath the center of the wheel which is opposite of what a car typically does. the back would then dip but there is force in the up and down direction so it obviously cant wheelie. u guys should think this thru for a little bit. as i already said before. doesnt an overhead rail car dive in the back when it brakes? all im saying is that where the momentum force is applied determines what dips and what doesnt. can u picture in your head what would happen if u had a high enough center of gravity and braked instantly. it would almost try to flip would it not? same goes if the center of gravity was low enough in relation to where its pivoting (the axle). and guess what, this is amazing...its also possible to have a center of mass somewhere that caused the car to not dip at all. isnt that something!!!

oh...and btw, no, mechanics isnt really physics. u really could call anything physics if u want since its loosely used all the time but maybe u should talk to a physicist. like i said, look up what kinda courses they take. very few of them even focus on kinematics and kinetics like they did in your high school class. physics isnt what 99.9% of people think it is. i guess this is a pointless argument too though to try to enlighten people on since people still seem to think its a law that the front of something dips when it slows down.

 

[gman07]

people still seem to think its a law that the front of something dips when it slows down.

I dont believe anyone ever said that. And I agree with you when you say the front end dipping isn't a law. But when talking about cars as they exist now, it is pointless to bring up the cases in which the front end wouldn't dip. It isnt a law; it is the effect of many laws on current cars.

 

[scarredgoth21]

I think they are flaps that come up when it was braking cause every picture I seen with these up it was sitting still or it was slowing down all the pictures I've seen of it so far with them down it was on a straight or accelerating

 

[flamingwonky]

Since when have you pulled a wheelie by braking too hard on your bike for example ?

Since I started biking in reverse

 

[EGFerio]

Since I started biking in reverse

may be it was mistaken for the throttle pedal

 

[jays83gsl]

Will someone buy this car in the game?

Just race it around the track. If they only raise during braking, they are obviously braking assists.

I hate to sound so harsh, but this is getting out of hand!

 

[jr93alty]

this is a little out of hand but...with the technology jump that we've had in the last few years, i wouldnt be suprised if cars do have incredibly low centers of gravity. with electric motors in the hubs and the removal of large oil pans, that allows u to reduce the height of weight quite considerably. corvettes already pull off an oddly low center of gravity so who knows. you'll always want weight transfer i suppose cuz braking the back heavily is usually useless. im sure drivers will change with the technology rather easily though. i'd imagine the first time u drove the car discussed in this thread, it'd catch u off guard. anyone ever personally driven a car with variable aerodynamics? ive been in a crossfire but thats the simplest of varied aerodynamics that u can get and nearly isnt noticeable.

 

[Hyundai Racer]

I dont believe anyone ever said that. And I agree with you when you say the front end dipping isn't a law. But when talking about cars as they exist now, it is pointless to bring up the cases in which the front end wouldn't dip. It isnt a law; it is the effect of many laws on current cars.

My point exactly; in fewer words. I tend to write too much. Bye! 👍

 

[scarredgoth21]

Will someone buy this car in the game?

Just race it around the track. If they only raise during braking, they are obviously braking assists.

I hate to sound so harsh, but this is getting out of hand!

i agree 👍

or win it if you can't buy it

 

[Martinmaxx]

Will someone buy this car in the game?

Just race it around the track. If they only raise during braking, they are obviously braking assists.

I hate to sound so harsh, but this is getting out of hand!

Those aerodynamic devices are fixed. You can see it for yourself in this video, that´s been here since Jan. 2nd : https://www.gtplanet.net/plugins/p13_download_manager/getfile.php?categoryid=31&fileid=144

It is a complete lap around the unchicaned Le Mans. When the roof cam is used, you can clearly see those flaps not moving at all.

 

[ExigeEvan]

That is the TVR Sagaris. It also has rear facing vents on the front wheel arch.

Why?

Because the vents release hot air from the brakes that would otherwise cause the front to rise (Hot air rises, basic physics.).

 

[Stune]

That is the TVR Sagaris. It also has rear facing vents on the front wheel arch.

Why?

Because the vents release hot air from the brakes that would otherwise cause the front to rise (Hot air rises, basic physics.).

THAT IS SUCH A COOL CAR

 

[EGFerio]

The MB 190 EVO II , Mitsu 3000 GT, JDM Supra(latest version), McLaren F1, Carrera GT, EB110, SLR, 911's, and many other street car also have active aero.

Which these active aero's are banned from racing. Even now for the new rules in F1 for 05. They don't even allow wings that flex in high speed which it will reduce CD's.

 

[jr93alty]

actually if u read the whole thread, you'll see that many people did argue thats its a law unless they've since edited them. even more, they tried to insult with pictures and other interesting statements that just didnt mean that much. but anyway, if these are static then i go back to guessing that they deflect air towards the rear wing instead of the line of the car along with releasing heat from the wheel well by using the front lower vents.

 

[Martinmaxx]

The MB 190 EVO II , Mitsu 3000 GT, JDM Supra(latest version), McLaren F1, Carrera GT, EB110, SLR, 911's, and many other street car also have active aero.

Which these active aero's are banned from racing. Even now for the new rules in F1 for 05. They don't even allow wings that flex in high speed which it will reduce CD's.

The MB 190 EVO II had active aero? That´s weird. Which were the "active" surfaces? Are they "active" in GT4?

 

[EGFerio]

The MB 190 EVO II had active aero? That´s weird. Which were the "active" surfaces? Are they "active" in GT4?

Look at the wing edge and the trunk edge.

Wing edge extends and the trunk edge tilts.

 

[superlemon]

i just said the mass would try to go underneath the center of the wheel which is opposite of what a car typically does.

If the suspension of the 'car' is mounted beneath the wheels then yes it will dip in braking (how weird would that be?!).

But we love cars the way they are thank you very much!

Gran Turismo = The Real Driving Simulator. Car physics is interesting enough for most people already.

 

[Martinmaxx]

Look at the wing edge and the trunk edge.

Wing edge extends and the trunk edge tilts.

I can see in your photos that the upper and lower wing surfaces are set in different angles, but are they actively controlled while moving? Or is it like the Lancer Evo wing, which can be adjusted manually. I remember that the BMW M3 Sport Evoution (the 190 Evo 2 DTM rival) also had adjustable front and rear wings, but they were not active.

I really like these old DTM road versions, and have read about them a lot, but never about active aero.

In this link you´ll find some nice pictures of both cars taking part in last year´s European Cannonball race : http://www.m5board.com/vbulletin/showthread.php?t=49992 and http://www.m5board.com/vbulletin/showthread.php?t=49978

 

[jr93alty]

If the suspension of the 'car' is mounted beneath the wheels then yes it will dip in braking (how weird would that be?!).

But we love cars the way they are thank you very much!

Gran Turismo = The Real Driving Simulator. Car physics is interesting enough for most people already.

and thank you. only problem is that it doesnt matter where the suspension is mounted. if u put the suspension "under" , as u call it, the wheel then it will just try to put the spring in tension during the brake. the front end will still dip because of the center of gravity. for the last time (hopefully) dipping is mainly from the weight distribution/center of gravity, not any part of the suspension. they control the weight transfer, not dictate it. and its still not a law. just a function of the line of the momentum of the center of gravity.

 

[cudadude2]

That is the TVR Sagaris. It also has rear facing vents on the front wheel arch.

Why?

Because the vents release hot air from the brakes that would otherwise cause the front to rise (Hot air rises, basic physics.).

accually its the high pressure in the wheelwells that causes the lift not the heat.

b

 

[superlemon]

and thank you. only problem is that it doesnt matter where the suspension is mounted. if u put the suspension "under" , as u call it, the wheel then it will just try to put the spring in tension during the brake. the front end will still dip because of the center of gravity. for the last time (hopefully) dipping is mainly from the weight distribution/center of gravity, not any part of the suspension. they control the weight transfer, not dictate it. and its still not a law. just a function of the line of the momentum of the center of gravity.

so what doesnt dip under braking?

 

[Hyundai Racer]

...since people still seem to think its a law that the front of something dips when it slows down.

I never said that the dipping of the suspension was a law. What I said is that the dipping is caused by the weight transfer, which is governed by the laws of physics. I come from a family of engineers (civil, mechanical, hydraulic and aerospace), and although I am not one (I am a helicopter mechanic and a student pilot) I know what I am talking about just by listening to my father, uncles and grandfather argue at dinner on the laws of physics...

 

[ixnay]

Maybe it is used for BOTH purposes? Aero on braking and ALSO cooling? Kill two birds with 1 stone. Sounds like good designing to me.

 

[Omnis]

omg, it is NOT a braking tool. it is aero, ventilation, or both.

 

[jr93alty]

so what doesnt dip under braking?

something with a center of gravity far enough below the pivot point (axle). like an overhead rail car. read the whole thread. and growing up in a family of engineers is fine i guess. but did u ever think that u may be arguing with a mechanical engineer. and i havent been paying attention to who is arguing with me so i dont know who ive been directing stuff at. but people WERE arguing that it was LAW and that i should shut up and go learn physics etc...but ive seen that they have since shut up. i never denied that the front of cars dip, but people should understand why that is instead of reading a some generalized info and applying it to the world. not pointing anybody out that did it, but it was done.

 

[superlemon]

so what if an overhead rail car does what it does? why can't you just agree for once that its a law in the world of cars? does it make you feel smart to nit-pick at other people's mistakes or generalizations?

anyways i think we know what the flaps are for. they are not for brake cooling or adding downforce directly and are not aerodynamic brakes . they reduce the pressure inside the wheel-well which affects the aerodynamics.

 

[A_newbie]

actually its not a law of physics for the front end to dip. its just the more efficient way to brake. thats why there are bigger brakes on the front of cars; to induce this action. the front of most cars weigh much more too which causes it to happen even more when the weight pivots around the wheel. but its not impossible to dip the back end of a car while braking, therefore not a law. but, now at least we see that they arent static.

Hey, against the flames that jr has endured, most of what he said is true.

Look at a car from the side that's moving forward to the left. When the car breaks, friction, a force that opposes any relative change in motion, kicks in. It points towards the back. But because both these forces are pointing counterclockwise relative to the car's center of mass, it produces torque to rotate the car in the counterclockwise direction, causing the back to rise and the front to dip (weight transfer forward). The normal forces from the front tire eventually counterbalance this rotation. So if you apply brakes slow enough so that the frictional force is small, you won't experience the front end dipping (what a surprise...). Like most of you said though, this is usually not the case and we do experience the front dipping. Put shortly, braking != dip.

For the point about more efficient braking, jr has a valid point again. Since you know that the front end of the car is subjected to higher normal forces than the back, giving the front larger brakes would help you stop faster. If you guys are still unconvinced, try riding a bike and compare the stopping distances if you 1) use only your front brakes and 2) only your rear brakes. Your rear brakes barely help because their contact with the ground is lessened as you brake.