Airbrakes on the Nissan R89C

[Omnis]

It looks like they are there strictly for downforce, but i have a feeling that cannot be right. Looking at Omnis' diagram, though, i dont understand where that air is coming from (the stuff that comes out behind the flaps). It seems that it can't be for brake cooling, as the air exits before reaching the brakes. They wouldnt make sense as airbrakes either unless they were movable.

that is where i'm confused too...

like i said before, i think the air from the duct whirls around the well before escaping. i have no idea though....so it's only a guess.

some air would escape from the wheel well itself, obviously...but i think an exit from behind the flap would create a vacuum that would suck some or most of the air out too.

i dont know if there even IS an opening there...this is just assuming that there is. no doubt the main purpose is aerodynamics though.

 

[JRizEJ6]

Mitsubishi HSR-II Concept '89 has airbrakes both on the rear and the front. Not only that but there are two, on one each side of the car and when the car is turning, only the airbrakes on the inside of the turn are activated. If you have an HSR-II it is well worth checking out in replay. The car is competitive in the Professional Hall turbo races. I won 133 A-Spec pts using it at Tokyo R246 with less than great driving.

Another "car" with airbrakes is the Nike One. I know it isn't a real car but the model in the game clearly shows an active airbrake at the rear. Watch it on replay.

Here's a picture of a real McLaren car:
Mercedes-Benz SLR McLaren - Rear Spoiler - 1600x1200 Wallpaper

is it just me, or does that hsr GREATLY resemble a firebird?

 

[Avenix]

let me get this straight....the HOT air from the front duct exits into the rear duct? i dont think so...

come to think of it....those flaps probably also serve the purpose of channeling the exiting air OVER the rear duct. i really dont think your line is even vaguely accurate of high-speed air travel.

this isnt perfect either....but i think it's more accurate. the yellow paths might be a little high though.

hmmm , this model does seem more accurate then mine , I think I am most confused about the ducts in the front , and thinking more of the venturi (effect) as seen in the toyota gt1, its nice to see some people who have some knowledge.. and not just talking off the top of their mind. 👍

 

[Omnis]

well....i'm no expert, but it does seem to make more sense. it'd be nice if we could have actual expertise on the matter though.

i think that nissan email isnt such a bad idea. lol.

 

[jr93alty]

im no expert (and obviously cant spell sense) but the top air ducts on the front of the car should not go to the wheel well. those are surely for a radiator and u wouldnt route that same air over the wheels unless for some odd reason the radiator is in the back of the car. i'd imagine air goes thru the bottom ducts on the front and is routed up along the tire for about 45 degrees of the tire then out the top. since air flowing perpendicular is the most efficient way to cool something. and the spinning tire doesnt really make a swirling wind anyway like a lot of people are saying. ever been around a wheel balancer? not much wind is there. not compared to the 100+mph coming thru the front which can be throttled to be even faster depending on what the engineers were trying to do. like i said though, im no expert and this is just my take. but i'll say once again, they arent air brakes but hopefully we've already established that.

 

[Omnis]

yeah...im just trying to bring about "what-if" scenarios. we dont really know details...but i guess our whole point is trying to guess those details.

jr, i was just messing around about the sense thing. lol. funny reply though.

we do know that ONE of the front pairs of holes is for the brakes. but they would all have similar plumbing anyway. i dont really know what other theories there are, or whatever. my educated guess is as good as anyone else's.

take it away, guys. lol.

 

[Eric.]

What is the deal in the square?

Nismo: Recommended paint change above.

 

[fangorn_forest]

Mirror possibly?

 

[jr93alty]

i just think everyone should know that there is a very large radiator located somewhere on the front of that car and i'd imagine it isnt too close to the ground. it also just makes sense for the lower ones to be the tire/brake coolers. the upper ones wouldnt deliver air for as long. it just makes sense to me that the large middle scoop and the two upper scoops are for the radiator since its sitting on a slant anyway and needs as much air as it can get. your guess is as good as mine. or probably better since i really dont care too much about these types of cars.

 

[Dew]

Has anyone seen the SLR airbrake working? I remember the GTR concept in GTC had an air brake that worked.......

That's some really good airbreaking!

 

[Omnis]

What is the deal in the square?

Nismo: Recommended paint change above.

that is a side mirror. the other mirror is located on the outside of the cockpit. (that black thing)

i found this one picture...

notice anything? the flaps arent up. maybe this means they aren't static anymore?

perhaps they are just spoilers that can be pre-adjusted as any other wing would be.

 

[SupraRZ97]

Those are used to draw in air and were used in racing to create up to 7000 lbs. of downforce at 200 mph.

 

[Hyundai Racer]

For one thing, they are not called "air brakes", but aerodynamic brakes.

There's a difference: air brakes are those found in buses and big trucks that have that queef (pfshhhh...) sound when the brake pedal is pressed and released. These are powered by compressed air that is stored in tanks. These buses/trucks have air pumps attached to the engine to provide pressure.

Air Brake for Bus/Truck:

Aerodynamic brakes are devices used mostly in airplanes that are made to disrupt aerodynamic flow over a certain body to induce drag and therefore reduce speed. Some japanese high speed trains use them too.

Aerodynamic Brakes on Airplanes:

Aerodynamic Brakes on a Train:

However, aerodynamic brakes on cars don't make much sense if they are on the front axle: when braking the front end dips, and the rear goes up (that's a law of physics). Air brakes will provide some downforce along with a slowing down force, so you want the air brake to be on the rear axle to create downforce and help keep the rear end low.

Those panels on the Nissan R89C look like breake heat dissipation panels (like mentioned before). Their main function is to open a door through which hot gases can dissipate when the car is braking. This car is capable of 200+ mph speeds, so those brakes (especially the front ones) produce an immense amount of energy, and that creates a lot of heat. That door is made to dissipate the heat. I suppose that this door does not open as much as pictured below when the car is going really fast. It probably opens an inch or two when the car is 100+ mph, then gradually as the car slows down, it opens more. A shown below, the car is probably going less than 60 mph when aerodynamics have less effect (any brick shaped car or bus can go 60 mph given adequate horsepower...)

Uh, sorry I had to get all technical and stuff.

 

[Hyundai Racer]

Yeah, I do like when discussions get technical...

Someone call Nissan on this one!

 

[jr93alty]

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.

 

[gman07]

actually its not a law of physics for the front end to dip.

Actually, it is. Momentum (or inertia) would tend to keep the car going, but there is a force applied to slow the car down. When a force is applied to slow the car down, the weight transfers forward (because inertia would tend to keep the car going in the same direction). Thus, the front end dips. The vents dont seem to be for brake cooling because the air exits the car out of them before reaching the brakes. My best guess is downforce.

 

[Otter]

While I'm not expert either, atleast not yet (studying autmotive engineering at the moment, done some work at the McLaren F1 team, hoping to be working in motorsport for a long time yet) I thought I might throw in my 2 pence.

My guess is, these 'flaps' or whatever you want to call them are to reduce the build up of high pressure inside the wheel well. Exiting high temperate air from the brakes doesn't really make sense. Throwing air like that out in that area would disrupt the air flow over the car quite considerably and could be better dispensed of elsewhere. Hot air is less dense than cold air remember. Why throw it in the path of the enginer air intakes and the rear wing. Why not get rid of it somewhere other than right into a clean airflow over the car? The reason why sometimes the flaps are open and other times closed is to alter the pressure distribution over the car. Just as you can alter the front and rear wings on the car to alter the downforce from and rear, you can also do small changes to other things to change the location of the centre of pressure on a car or the effectiveness of various aerodynamic devices for different circuits. Some of the front diffuser feeds air into these wheel wells, which is why on most cars you see vents over the front wheels and not the rears. Having the flaps acting almost as a wing to produce downforce doesn't really seem a very efficient way of making downforce either. Most wings you see have the side fences on them to stop air escaping over the side to the low pressure underneigh and to force it over the wing. These don't.

Looking at the development of various Nissan's over the years it looks like they switched from the large vents seen of this car to the more common grills we see on cars such as the R8 today. However some of their cars also have these vents even further foward of the front wheel, which confuses me a bit. I don't have a windtunnel though!

I've attached some pictures of various LM Nissans over the ages to try and explain it. Not sure how to get them into the post though, and it's too late for me to go read how to post. I'll try it again tomorrow if it doesn't work.

Sorry if this doesn't make a lot of sense. It's late, I'm tired, I should be revising, not posting!

 

[superlemon]

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.

everything about this quote is wrong...ignore it!

 

[EGFerio]

Actually, it is. Momentum (or inertia) would tend to keep the car going, but there is a force applied to slow the car down. When a force is applied to slow the car down, the weight transfers forward (because inertia would tend to keep the car going in the same direction). Thus, the front end dips. The vents dont seem to be for brake cooling because the air exits the car out of them before reaching the brakes. My best guess is downforce.

The vent is to extract air out to prevent low pressure built up in wheel well thus prevent induce lift at front.

 

[gman07]

Ahh, that makes sense. Thanks for the clarification.

 

[Hyundai Racer]

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.

You need to go back to school and study the basic laws of physics:

And while you at it, read the wonderful Physics of Racing series to understand why a car's front end dips when you brake:

The Physics of Racing Series

Here's some more educational good stuff:

NASA's Physics of Racing

Enjoy!

 

[jr93alty]

everything about this quote is wrong...ignore it!

really? what actually happens is inertia, like it was said before. its just that the foward force of the car is above the center of the wheel, therefore making the moment of inertia push the front of the car down. for everyone that is claiming i am wrong saying that it is completely impossible to get that force below the center of a wheel? it would take quite a large mass i know but its possible to have more force under the centerline that could overcome the "inerita multiplied by the angular acceleration." it'd be a stretch. kinda like riding in something that rode on a rail above u. when it braked, the front would go up because the line of the momentum is under the center of whatever is driving and braking it. call it a stretch if u want but its true. its not a law of physics and thats all im saying. just cuz u brake a mass doesnt make the front dip. there are many more factors like center of gravity, brake balance, etc...if we wanna model this in some software we can. so if u still wanna ignore me and advise others to ignore me, better come up with some proof that makes sense. show a free body diagram or something. but i guarantee that i could model something in a software package that would prove that im right. it may have very large wheels but it'd work, therefore proving its not a law.

 

[jr93alty]

hey hyundai racer...how old are u? what u posted means nothing. of course there's always a reaction. why dont u show me the line of the action though in relation to the wheel? i know every car dips in the front. will u guys just pay attention though...its not a law of physics and it isnt REQUIRED to happen. it just so happens that it happens with the masses and the location of those masses on cars. ok whatever, maybe i was being picky but i was just correcting something. i can drop if u want though. its a stupid argument. im not talking high school physics here. it wouldnt be a constant mass anyway if u wanna get technical and try to show pictures that u think are funny. the perceived mass is variable since fluid is sloshing and gasoline is also always burning. so, that was a nice picture, but not too impressive or funny.

 

[Hyundai Racer]

hey hyundai racer...how old are u? what u posted means nothing. of course there's always a reaction. why dont u show me the line of the action though in relation to the wheel? i know every car dips in the front. will u guys just pay attention though...its not a law of physics and it isnt REQUIRED to happen. it just so happens that it happens with the masses and the location of those masses on cars. ok whatever, maybe i was being picky but i was just correcting something. i can drop if u want though. its a stupid argument. im not talking high school physics here. it wouldnt be a constant mass anyway if u wanna get technical and try to show pictures that u think are funny. the perceived mass is variable since fluid is sloshing and gasoline is also always burning. so, that was a nice picture, but not too impressive or funny.

Man, take a breath! Relax, it's just a forum argument... I am 30 years old if you wanna know. And yes, it is a law of physics... According to the first law of physics a body will continue in its current state unless acted upon by another force. It doesn't hurt to read the Physics of Racing series, it's a great seres. I am not going to draw pretty pictures for you, but if you really want to understand it, read this:

Weight Transfer

 

[jr93alty]

nice article. but i still ask the question...do u think its completely impossible for the "current state" or whatever u want to call it to attempt to continue going foward except at a line underneath the axle? imagine a bicycle with a very large front wheel and a tiny rear wheel. if there was a seat above that rear wheel that was still below the center of the front wheel and a relatively large mass was on that seat and this bike was traveling at a high speed and the front wheel suddenly stopped; the weight on the seat would continue trying to go foward like u keep saying. only problem is, it would be on a line underneath the center of the wheel, therefore the moment would be in the opposite direction and if it was large enough it would overpower all inertial forces of the wheel. try to stay away from generalized internet documents for the laymen. they are simplified explanations of what USUALLY happens. they wouldnt be paying engineers so much if a simple internet document explained weight transfer and centers of gravity and whatnot. so once again...yes, car's front ends dip but it is NOT a law of physics. an object continuing its motion doesnt determine which direction the moment will be in, rather the location of application of that objects force. simple documents like these is what makes people think they fully understand bore/stroke ratios, head design, piston design, etc...very rarely can u generalize things when it comes to airplane and car design (or anything else for that matter). thats why in this topic, our best guess is about all we can give unless we know something specific about this car or we helped design it. there are too many factors in determining how a car reacts. a simple document on weight transfer or drawings of guessed airstreams does nothing unless youve seen a simulation.

 

[MarioAndretti]

The vent is to extract air out to prevent low pressure built up in wheel well thus prevent induce lift at front.

That can't what they're for.If you look just behind them and right over top of the wheels,you'll see slots just like the audi r8.Those are for venting air from the wheel wells.They must be adjustable aerodynamic flaps.Keep them down for low drag on straight high speed tracks,up in a high downforce configuration for slower tighter turning tracks for better manuverabilty.This makes the car more versitile,improving performance on different tracks,to maximise the possibility of an overall season championship.
As for the SLR.That's not an airbrake,it's an automaticly deployed spoiler.It pops up when the car exceeds a certain speed.Porche uses the same thing on the 911.

 

[Hyundai Racer]

nice article. but i still ask the question...do u think its completely impossible for the "current state" or whatever u want to call it to attempt to continue going foward except at a line underneath the axle? imagine a bicycle with a very large front wheel and a tiny rear wheel. if there was a seat above that rear wheel that was still below the center of the front wheel and a relatively large mass was on that seat and this bike was traveling at a high speed and the front wheel suddenly stopped; the weight on the seat would continue trying to go foward like u keep saying. only problem is, it would be on a line underneath the center of the wheel, therefore the moment would be in the opposite direction and if it was large enough it would overpower all inertial forces of the wheel. try to stay away from generalized internet documents for the laymen. they are simplified explanations of what USUALLY happens. they wouldnt be paying engineers so much if a simple internet document explained weight transfer and centers of gravity and whatnot. so once again...yes, car's front ends dip but it is NOT a law of physics. an object continuing its motion doesnt determine which direction the moment will be in, rather the location of application of that objects force. simple documents like these is what makes people think they fully understand bore/stroke ratios, head design, piston design, etc...very rarely can u generalize things when it comes to airplane and car design (or anything else for that matter). thats why in this topic, our best guess is about all we can give unless we know something specific about this car or we helped design it. there are too many factors in determining how a car reacts. a simple document on weight transfer or drawings of guessed airstreams does nothing unless youve seen a simulation.

Man, you really gotta learn some physics. Laws of physics explain everything (unless you live in a non-physical world); the problem is that there lots of them (not only the basic three; they are called basic for a reason) and, like you said, there are always many variables that come into play in, say, a car or an airplane. If you do read the whole Physics of Racing you will see how it goes more in depth on weight transfer.

I've had enough of this argument. Take care and good racing!

 

[Ten]

or whatever u want to call it

Terms like that really tend to hurt whatever kind of scientific point you're trying to make.

 

[Martinmaxx]

As for the SLR.That's not an airbrake,it's an automaticly deployed spoiler.It pops up when the car exceeds a certain speed.Porche uses the same thing on the 911.

That is not accurate. If you check the SLR´spoiler/speed brake in motion, you ´ll see that it partially raises above a certain speed (like a Porsche), but when you brake hard, it fully raises to almost 90 degrees, functioning as a speed brake (unlike a Porsche).

As for the Mitsubishi prototype with active aerodynamics (HSR-2 ´89) that someone mentioned in an earlier post, let me tell you that it works beautifully in GT4 : When you turn right, the right side of the rear spoiler raises and right front wing extends. The opposite happens while turning left. When you brake, all active aero deploys at the same time. Very interesting concept indeed.

 

[jr93alty]

Terms like that really tend to hurt whatever kind of scientific point you're trying to make.

its because i was arguing something. and u all can think whatever u want but the fact of the matter is that if a force acts underneath the center of something, the moment will be in the clockwise direction (if the force is pointing left) and anyone that doesnt understand that needs some help. and thats not physics, its mechanics. a lot of people dont even truly understand what "physics" is. look up a course outline of a physics major and tell me what u find. weight transfer is typically covered in a vehicle dynamics course which is a mechanical engineering class. there arent many, if any, physicists designing any cars. as soon as u can show me that its impossible for a large force to act under the center of a wheel then u can all talk **** and continue trying to insult me. but say something educated that makes sense first. u guys are basically saying that any mass that hits a wall or something will try to flip rear end over front end and thats just not true. it depends where the opposing force was at and the specifications of the mass. if this doesnt make sense then maybe a lot of u should stick to video games.

p.s. have u all forgotten that i said that a car front end does in fact dip? im just making a point that it isnt a LAW. dont take simple data from a website and make generalized assumptions from them or else youre gonna be in trouble when u try to design something.