Side Exhausts and aerodynamics with pics
01-05-2010, 11:44 AM
#31
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Lastly,
Here are my Vortex generators and Gurney Flap. I added the flap to help balance the car after I installed the front splitter.
Thanks for letting me share some of my work in your thread and good luck.
Ken
Here are my Vortex generators and Gurney Flap. I added the flap to help balance the car after I installed the front splitter.
Thanks for letting me share some of my work in your thread and good luck.
Ken
01-05-2010, 11:56 AM
#32
Rennlist Member
Your side exhaust idea is a great one.
If I was goint to undertake that project I would utilize one the the Spintech mufflers with the 2.5 inch round in and 2.5 inch oval out. Then you could run their oval tubing (1 3/4 inch x 3inch) as your outlets and cut them off at the same profile as the vehicle edge.
A guy might be able to save another 6-8 pounds of weight over the rear exit.
That would also clean up some of the area back there for a rear diffuser and keep some of the heat off of the transaxel.
Now look what you've started !!!
Ken
If I was goint to undertake that project I would utilize one the the Spintech mufflers with the 2.5 inch round in and 2.5 inch oval out. Then you could run their oval tubing (1 3/4 inch x 3inch) as your outlets and cut them off at the same profile as the vehicle edge.
A guy might be able to save another 6-8 pounds of weight over the rear exit.
That would also clean up some of the area back there for a rear diffuser and keep some of the heat off of the transaxel.
Now look what you've started !!!
Ken
01-05-2010, 01:06 PM
#33
So what is the 80/20 ratio here Greg? How could a random person get, say, a 928 to have 80% of these benefits with 20% of the work and testing? The 80/20 rule says that you can get 80% of the result for 20% of the work/input, and to get the rest of the result (20%) you would have to put in 80% more work. The difference is seen with things like GP2 vs F1. Those GP2 cars are 20% of the work. But they get 80% of the output/performance (approx) of the F1 cars.
So - stick a moderate diffuser on the front of a 928, put a flat floor under everything, and a rear thing like the ferarris have, and add some hood vents facing backwards. Thats a bit of work, but it would improve what exactly? Speed and handling above 100mpg? Or below?
So - stick a moderate diffuser on the front of a 928, put a flat floor under everything, and a rear thing like the ferarris have, and add some hood vents facing backwards. Thats a bit of work, but it would improve what exactly? Speed and handling above 100mpg? Or below?
01-05-2010, 01:42 PM
#34
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you understand what the vortex generators are used for as well as the gurney flap right? the gurney flap used to effectively increase the wing angle of attack, with a little less drag in some cases. Vortex generators are used to keep the air flow from separating off the body as the downward slope of the hatch would cause separation as well as rendering the wing less effective. the vortex gens, at a cost of drag , keep the air flow near attached to the rear window, made even harder by the little recess of the window itself. this is to make the rear wing receive more air flow. on airplanes , they use them to give the control surfaces more control at slow speeds.
Now, you can easily test if that wing and vortex are working. leave the wing ajar and go for a ride on the freeway. see how fast you have to go before the rear hatch actually locks. you will find that if you were able to raise your wing up in the air stream, and increase the angle of attack, you would have much more gains than you get by using gurney flaps and vortex gens. that wing is totally flat and is barely an air foil as well. It needs some angle to really be effective. But it does look good!
Now, you can easily test if that wing and vortex are working. leave the wing ajar and go for a ride on the freeway. see how fast you have to go before the rear hatch actually locks. you will find that if you were able to raise your wing up in the air stream, and increase the angle of attack, you would have much more gains than you get by using gurney flaps and vortex gens. that wing is totally flat and is barely an air foil as well. It needs some angle to really be effective. But it does look good!
01-05-2010, 01:49 PM
#35
Rennlist Member
And that is exactly right. use of a splitter, hood vent, and wing give you 80% of what the total potential would be for optimized flow and control aids.
you dont even need the flat bottom or rear defuser. those are far less effective at the speeds you reach on a race track in cars like ours and the power we have. for the most part, the flat bottom and rear diffuser, is really for drag. (not much gain there). you can model this and see the effects.
Heck, if I thought there was a reasonable value for a flat bottom, I would do some work in that area. Ive penciled it out and the gains are less in areas of drag, than the wing costs. in the end, it ain't much.
the most bang for the buck is getting the air from hitting the front of the car, to go over the car and not under it. (i.e. splitter, hood vent, air dam, etc)
you dont even need the flat bottom or rear defuser. those are far less effective at the speeds you reach on a race track in cars like ours and the power we have. for the most part, the flat bottom and rear diffuser, is really for drag. (not much gain there). you can model this and see the effects.
Heck, if I thought there was a reasonable value for a flat bottom, I would do some work in that area. Ive penciled it out and the gains are less in areas of drag, than the wing costs. in the end, it ain't much.
the most bang for the buck is getting the air from hitting the front of the car, to go over the car and not under it.
(i.e. splitter, hood vent, air dam, etc)So what is the 80/20 ratio here Greg? How could a random person get, say, a 928 to have 80% of these benefits with 20% of the work and testing? The 80/20 rule says that you can get 80% of the result for 20% of the work/input, and to get the rest of the result (20%) you would have to put in 80% more work. The difference is seen with things like GP2 vs F1. Those GP2 cars are 20% of the work. But they get 80% of the output/performance (approx) of the F1 cars.
So - stick a moderate diffuser on the front of a 928, put a flat floor under everything, and a rear thing like the ferarris have, and add some hood vents facing backwards. Thats a bit of work, but it would improve what exactly? Speed and handling above 100mpg? Or below?
So - stick a moderate diffuser on the front of a 928, put a flat floor under everything, and a rear thing like the ferarris have, and add some hood vents facing backwards. Thats a bit of work, but it would improve what exactly? Speed and handling above 100mpg? Or below?
01-05-2010, 02:25 PM
#36
Rennlist Member
You said,
"The floor is basically flat but with a few tricks. Notice the lower front end treatment, this is what I mentioned before, guide the air away from the tyres and send plenty of air under the car."
No, you dont want more air "under the car". the hood vents are good. the splitter takes the air that wasnt enteriing the radiator and engine, and routes it to the sides. the front lower fenders , futher route the air to the sides. (ambient pressure as is under the car)
As far as the vents size and efficiency, Ive already done measurements to see their effects. Dont confuse efficiency with effectiveness. There is not a huge amount of vacuum over the hood, but it is a large area. small vents certainly do something , but to take full advantage you need to get the air out. look at the inlet size where the air comes from. minus the pressure drop across the radiator and duct, and that points to the size you need going out of the hood. anything less and that air will go under the car.
also, to your point of the lower drag. the pressure build up in the engine bay has a very easy time going under the car. there is not much drag saved there going over the hood. in fact, maybe more due to increased downforce and thus increased rolling friction. the gain is that you take that air that easily will go under the car out of the engine bay, and route it to the vents over the car. this is a common misconception. Also, even if the engine bay was pressurized, that is not more drag as it makes a bubble up front and the oncoming air just flows naturally to the path of least resistance. over, under, to the sides. Its like the inlet of a F86 or F16. if it is completely vented, you can almost subtract it from the frontal area. however, since it is vented to hood, that air mass hits the windshield and increases it's effect on frontal area for that section. you cant leave out any variables. you have to dig deep to understand what is really going on with the air flow and all the trade offs. (most of which are measurable)
flat under the car area doesnt speed up the air on its own. think of it as if it was over the car. dirty aero shapes over the car would just create drag but could reduce vacuum. think of the car as a wing and the under car is the flat part of the wing. we are trying to keep the wing from flying. the top of the car (the air foil section) creates most of the lift. under the wing (bottom of the car) is not very effective either way. in fact, wings dont even need bottoms to create lift. its mainly for drag. under the car is the same thing. its a fixed speed, unless you have a defuser or venturi tunnels. that speed of air can be dense or not dense. splitters help reduce the mass of air that the car is rolling over. This is why wings are flat on the bottom. they create smooth air flow, not lower pressure. .
"The floor is basically flat but with a few tricks. Notice the lower front end treatment, this is what I mentioned before, guide the air away from the tyres and send plenty of air under the car."
No, you dont want more air "under the car". the hood vents are good. the splitter takes the air that wasnt enteriing the radiator and engine, and routes it to the sides. the front lower fenders , futher route the air to the sides. (ambient pressure as is under the car)
As far as the vents size and efficiency, Ive already done measurements to see their effects. Dont confuse efficiency with effectiveness. There is not a huge amount of vacuum over the hood, but it is a large area. small vents certainly do something , but to take full advantage you need to get the air out. look at the inlet size where the air comes from. minus the pressure drop across the radiator and duct, and that points to the size you need going out of the hood. anything less and that air will go under the car.
also, to your point of the lower drag. the pressure build up in the engine bay has a very easy time going under the car. there is not much drag saved there going over the hood. in fact, maybe more due to increased downforce and thus increased rolling friction. the gain is that you take that air that easily will go under the car out of the engine bay, and route it to the vents over the car. this is a common misconception. Also, even if the engine bay was pressurized, that is not more drag as it makes a bubble up front and the oncoming air just flows naturally to the path of least resistance. over, under, to the sides. Its like the inlet of a F86 or F16. if it is completely vented, you can almost subtract it from the frontal area. however, since it is vented to hood, that air mass hits the windshield and increases it's effect on frontal area for that section. you cant leave out any variables. you have to dig deep to understand what is really going on with the air flow and all the trade offs. (most of which are measurable)
flat under the car area doesnt speed up the air on its own. think of it as if it was over the car. dirty aero shapes over the car would just create drag but could reduce vacuum. think of the car as a wing and the under car is the flat part of the wing. we are trying to keep the wing from flying. the top of the car (the air foil section) creates most of the lift. under the wing (bottom of the car) is not very effective either way. in fact, wings dont even need bottoms to create lift. its mainly for drag. under the car is the same thing. its a fixed speed, unless you have a defuser or venturi tunnels. that speed of air can be dense or not dense. splitters help reduce the mass of air that the car is rolling over. This is why wings are flat on the bottom. they create smooth air flow, not lower pressure. .
Well I hope those ducts do look good, I suppose it will depend on the welder
, however while they are not the ultimate and as I mentioned before there is a balance to be had in this case between aesthetics and function.
The vents may well surprise you as they are rearward facing I think what you may have failed to consider is that the pressure in the engine bay along with the suction of the air running over the body will make these very efficient for their size.
I am looking more at reducing the lift that is there plus reducing the drag, the 599 is a big car, bigger than a 928 but has a better Cd number, these vents/ducts are some of the reasons. Think about it, if there is a pressure build up there must be some drag being caused, let the air pressure escape, should be less drag.
Now if you want to take it a step further have a look at this car, this is probably more applicable than the examples you offered, the reason is the layout, front engined rear tranaxle, the exception being the Volvo but that is as ugly as a hat full of arseholes and I don't want to go there
This is the car's big brother from where I got my vents, it develops 280 kg of downforce at 125 mph, a speed I am sure it is constantly above!
You will notice the bonnet vents, all engine bay air exits through these vents, the engine bay is completely enclosed. The floor is basically flat but with a few tricks. Notice the lower front end treatment, this is what I mentioned before, guide the air away from the tyres and send plenty of air under the car.
By Mark kibort
I wasn't going to say anything here but you are sort of contradicting yourself here, the pure fact that you say there is turbulence now means there is a difference. You see when the put the flat floor and connect it to the air dam/spoiler you smooth out the flow and as such the air will run faster. Faster air will create a low pressure zone.
You are correct in saying there is turbulent air there but a more complete statement, would be, there is reduced air traveling under the car due to the air dam and there is a wake like low pressure turbulence behind it. To say there is no difference is wrong because while there is probably little difference in the actual results and I do note the examples you quote. However in my case there is a detailed underbody and then a diffuser. That then makes a world of difference.
Cheers Greg
, however while they are not the ultimate and as I mentioned before there is a balance to be had in this case between aesthetics and function.The vents may well surprise you as they are rearward facing I think what you may have failed to consider is that the pressure in the engine bay along with the suction of the air running over the body will make these very efficient for their size.
I am looking more at reducing the lift that is there plus reducing the drag, the 599 is a big car, bigger than a 928 but has a better Cd number, these vents/ducts are some of the reasons. Think about it, if there is a pressure build up there must be some drag being caused, let the air pressure escape, should be less drag.
Now if you want to take it a step further have a look at this car, this is probably more applicable than the examples you offered, the reason is the layout, front engined rear tranaxle, the exception being the Volvo but that is as ugly as a hat full of arseholes and I don't want to go there
This is the car's big brother from where I got my vents, it develops 280 kg of downforce at 125 mph, a speed I am sure it is constantly above!
You will notice the bonnet vents, all engine bay air exits through these vents, the engine bay is completely enclosed. The floor is basically flat but with a few tricks. Notice the lower front end treatment, this is what I mentioned before, guide the air away from the tyres and send plenty of air under the car. By Mark kibort
I wasn't going to say anything here but you are sort of contradicting yourself here, the pure fact that you say there is turbulence now means there is a difference. You see when the put the flat floor and connect it to the air dam/spoiler you smooth out the flow and as such the air will run faster. Faster air will create a low pressure zone.
You are correct in saying there is turbulent air there but a more complete statement, would be, there is reduced air traveling under the car due to the air dam and there is a wake like low pressure turbulence behind it. To say there is no difference is wrong because while there is probably little difference in the actual results and I do note the examples you quote. However in my case there is a detailed underbody and then a diffuser. That then makes a world of difference.
Cheers Greg
01-05-2010, 02:52 PM
#37
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Its a real nice splitter. it would be easy to add a section for the race track that clips or bolts on with supports up front. the problem with our car, is that we have a long nose! the splitter can help make this nose look shorter or blunt to the oncoming air flow, but the splitter needs to be out as far as the nose, or a least a little further. I was able to measure full ram pressure of near .2psi, all the way out to the edge of my 8" splitter in its largest form. remember, i was able to increase its size by extending it. if the car has a blunt nose, this effect falls off pretty fast, and is the reason that cars like the volvo or even 944, dont need the length of splitter as we do.
the splitter is angled down by 17 degrees? that is hard to see in the picture. 17 degrees is the highest angle that you will find on any wing, car or plane. my wing is only angled 7 degrees for example.
I like to see the oil pan in the air stream as I believe it is good source of cooling for the oil. Im sure Scot might want to copy this mod for his 5 liter euro racer.
the splitter is angled down by 17 degrees? that is hard to see in the picture. 17 degrees is the highest angle that you will find on any wing, car or plane. my wing is only angled 7 degrees for example.
I like to see the oil pan in the air stream as I believe it is good source of cooling for the oil. Im sure Scot might want to copy this mod for his 5 liter euro racer.
01-05-2010, 06:21 PM
#38
Rennlist Member
The splitter itself is 70 mm if I recall and trails back under the spoiler by about 13-14 inches. The diffuser is built at an angle of 17 degrees.
the splitter is angled down by 17 degrees? that is hard to see in the picture.
The splitter is as close to Zero angle of attack as I could get. I am talking about the underside diffuser, which is built at 17 degrees so that I don't get boundary separation. Pictures 1 & 2 I believe on the prior page. The diffuser is on the underside of the splitter.
The advantage of the diffuser is that is helps accelerate the air. By creating additional low pressure under the nose with the diffuser, the splitter doesn't need to be as long. With this placement I am also getting some additional cooling benefits on the finned pan.
Regards,
Ken
Last edited by Vlocity; 01-05-2010 at 07:07 PM.
01-05-2010, 07:15 PM
#39
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Ken you are more than welcome to post pics and I would invite others if they so wish. I like your execution of the front end and think what you have achieved is likely to be quite beneficial on reward for effort basis. The rear is interesting too with what "almost" looks like a double element wing.
Mark, I will need some time to look at what you said as it is obviously quite different to what I am saying. While I don't really want to bring F1 design into this discussion as I think it is important to try and stay as close to what we have is possible, there is some common themes in these high end cars.
So what I would like you to address and I think I know what your response will be is why the designer or designers of the 599XX choose to run as much air under the car as they can get and why F1 designers also do the same?
Have a look at the floor of the Ferrari Enzo
Again the question is why are they trying to let or get as much air as possible under the car? This while not the 599XX will be fairly similar as the 599XX does not vent its engine bay air to the underbody. I also believe the reason that they don't vent the engine bay air under the car is that is is turbulent and this again would fit with my proposition that the smooth underbody smooths the airflow and then speeds the air up and as such creates a local low pressure zone and with resultant downforce.
Greg
Mark, I will need some time to look at what you said as it is obviously quite different to what I am saying. While I don't really want to bring F1 design into this discussion as I think it is important to try and stay as close to what we have is possible, there is some common themes in these high end cars.
So what I would like you to address and I think I know what your response will be is why the designer or designers of the 599XX choose to run as much air under the car as they can get and why F1 designers also do the same?
Have a look at the floor of the Ferrari Enzo
Again the question is why are they trying to let or get as much air as possible under the car? This while not the 599XX will be fairly similar as the 599XX does not vent its engine bay air to the underbody. I also believe the reason that they don't vent the engine bay air under the car is that is is turbulent and this again would fit with my proposition that the smooth underbody smooths the airflow and then speeds the air up and as such creates a local low pressure zone and with resultant downforce.
Greg
01-05-2010, 07:50 PM
#40
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Greg and Mark,
It is actually somewhat simple why the current shift to run air under the car. The amount of air is controlled based on venturi opening etc. to increase velocity and create a low pressure zone under the car.
However, the main thing is the shape of the venturis, and the underside, which CFD modeling can address prior to build. If you look closely, the venturis under the car are shaped as upside down wings, which create {negative lift} aka downforce...
The controlled airflow under the car is used to create downforce where in prior situations and design, the airflow was routed around, and over the car....
You are both correct, it is the interpretation of the designer's intent, and use of the vehicle.... Some places allow much faster continuous driving and higher top speed than others.. In other areas, more downforce at slower terminal velocity is more important..
Pick your use, and design for it, including compromises...!
There, I'm now a referee.....
It is actually somewhat simple why the current shift to run air under the car. The amount of air is controlled based on venturi opening etc. to increase velocity and create a low pressure zone under the car.
However, the main thing is the shape of the venturis, and the underside, which CFD modeling can address prior to build. If you look closely, the venturis under the car are shaped as upside down wings, which create {negative lift} aka downforce...
The controlled airflow under the car is used to create downforce where in prior situations and design, the airflow was routed around, and over the car....
You are both correct, it is the interpretation of the designer's intent, and use of the vehicle.... Some places allow much faster continuous driving and higher top speed than others.. In other areas, more downforce at slower terminal velocity is more important..
Pick your use, and design for it, including compromises...!
There, I'm now a referee.....
01-05-2010, 11:22 PM
#41
Rennlist Member
Now I understand. sure, that is a possibility, but its not like the trailing edge is the end of an air foil. its kind of like the air that is moving to the sides of the car. open a window, and you dont have the separation like what comes off the rear of most cars. this is where the separation becomes a problem (measureable problem or value)
diffusers do not "accelerate the air" they actually slow down the air. venturies speed up the air and lower the pressure at a cost of some pressure drop across it. (i.e. drag) Must of the use of diffusers and tunnels and venturis are used for stability, control, and cooling of brakes.
The cooling benefit, is certainly a charaterstic I endorse for relatively unmodified motors cooling systems like ours.
can you explain the first drawing. is that the "defuser" that is pointed to the oil pan, or am i looking at a side view. Im just trying to understand what the big circle is and where those winglets are on your car.
mk
diffusers do not "accelerate the air" they actually slow down the air. venturies speed up the air and lower the pressure at a cost of some pressure drop across it. (i.e. drag) Must of the use of diffusers and tunnels and venturis are used for stability, control, and cooling of brakes.
The cooling benefit, is certainly a charaterstic I endorse for relatively unmodified motors cooling systems like ours.
can you explain the first drawing. is that the "defuser" that is pointed to the oil pan, or am i looking at a side view. Im just trying to understand what the big circle is and where those winglets are on your car.
mk
Ken
Mark,
The splitter is as close to Zero angle of attack as I could get. I am talking about the underside diffuser, which is built at 17 degrees so that I don't get boundary separation. Pictures 1 & 2 I believe on the prior page. The diffuser is on the underside of the splitter.
The advantage of the diffuser is that is helps accelerate the air. By creating additional low pressure under the nose with the diffuser, the splitter doesn't need to be as long. With this placement I am also getting some additional cooling benefits on the finned pan.
Regards,
Ken
Mark,
The splitter is as close to Zero angle of attack as I could get. I am talking about the underside diffuser, which is built at 17 degrees so that I don't get boundary separation. Pictures 1 & 2 I believe on the prior page. The diffuser is on the underside of the splitter.
The advantage of the diffuser is that is helps accelerate the air. By creating additional low pressure under the nose with the diffuser, the splitter doesn't need to be as long. With this placement I am also getting some additional cooling benefits on the finned pan.
Regards,
Ken
01-05-2010, 11:37 PM
#42
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The double wing gives the assistance with the separation issues, as well has having the downforce potential, but a little more angle would serve him better.
Take a look at what i have said and see if it makes sense or if you agree.
Now, why do you think the designers run as much air as they can? the splitter and inlet, with hood vents suggest the opposite. see the pics Ive posted, as those all show the theme of not having much air under the car for better downforce. its all about the ratio of the air that goes under the car vs over the car. think of the concept of the hood vents, and you will break the code. you have as much or more air going over the car based on the nose position. yet, with hood vents, the air traveling under the car normally, would now be routed over the hood, feeding the low pressure zone to reduce the low pressure zone at the hood. the more air molecules going over the ar, the lower the pressure differential vs under the car and that is the goal.
again, think of the car as a wing, actually right side up. air under the car is ambient pressure. this is easy to measure, even at 120mph. over the car the pressure drops dramatically with speed. also easy to measure. you can do things locally with venturis and diffusers, but you are just moving around air flow speeds and pressure. robbing Peter to pay Paul, so to speak. Ill have to dig up this discussion we had on the racing board about this. they show how the venturis and diffusers are used under the car. (F1 included). with F1, you have venturi tunnels that increase the speed of the air, reduce the pressure and create massive downforce. the diffusers at the rear would then be a efficient way to have the air exiting the undercar area, with the least amount of drag. I dont think we are talking venturi tunnels here.
Take a look at what i have said and see if it makes sense or if you agree.
Now, why do you think the designers run as much air as they can? the splitter and inlet, with hood vents suggest the opposite. see the pics Ive posted, as those all show the theme of not having much air under the car for better downforce. its all about the ratio of the air that goes under the car vs over the car. think of the concept of the hood vents, and you will break the code. you have as much or more air going over the car based on the nose position. yet, with hood vents, the air traveling under the car normally, would now be routed over the hood, feeding the low pressure zone to reduce the low pressure zone at the hood. the more air molecules going over the ar, the lower the pressure differential vs under the car and that is the goal.
again, think of the car as a wing, actually right side up. air under the car is ambient pressure. this is easy to measure, even at 120mph. over the car the pressure drops dramatically with speed. also easy to measure. you can do things locally with venturis and diffusers, but you are just moving around air flow speeds and pressure. robbing Peter to pay Paul, so to speak. Ill have to dig up this discussion we had on the racing board about this. they show how the venturis and diffusers are used under the car. (F1 included). with F1, you have venturi tunnels that increase the speed of the air, reduce the pressure and create massive downforce. the diffusers at the rear would then be a efficient way to have the air exiting the undercar area, with the least amount of drag. I dont think we are talking venturi tunnels here.
The rear is interesting too with what "almost" looks like a double element wing.
Mark, I will need some time to look at what you said as it is obviously quite different to what I am saying. While I don't really want to bring F1 design into this discussion as I think it is important to try and stay as close to what we have is possible, there is some common themes in these high end cars.
So what I would like you to address and I think I know what your response will be is why the designer or designers of the 599XX choose to run as much air under the car as they can get and why F1 designers also do the same?
Have a look at the floor of the Ferrari Enzo
Again the question is why are they trying to let or get as much air as possible under the car? This while not the 599XX will be fairly similar as the 599XX does not vent its engine bay air to the underbody. I also believe the reason that they don't vent the engine bay air under the car is that is is turbulent and this again would fit with my proposition that the smooth underbody smooths the airflow and then speeds the air up and as such creates a local low pressure zone and with resultant downforce.
Greg
Mark, I will need some time to look at what you said as it is obviously quite different to what I am saying. While I don't really want to bring F1 design into this discussion as I think it is important to try and stay as close to what we have is possible, there is some common themes in these high end cars.
So what I would like you to address and I think I know what your response will be is why the designer or designers of the 599XX choose to run as much air under the car as they can get and why F1 designers also do the same?
Have a look at the floor of the Ferrari Enzo
Again the question is why are they trying to let or get as much air as possible under the car? This while not the 599XX will be fairly similar as the 599XX does not vent its engine bay air to the underbody. I also believe the reason that they don't vent the engine bay air under the car is that is is turbulent and this again would fit with my proposition that the smooth underbody smooths the airflow and then speeds the air up and as such creates a local low pressure zone and with resultant downforce.
Greg
Last edited by mark kibort; 01-06-2010 at 12:15 AM.
01-06-2010, 12:38 AM
#43
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Just a quick response, F1 cars do not have venturi tunnels and have not had them for 20 odd years, that is not the reason for their downforce. They develop their underbody downforce by the same principle as I have been explaining, lots of air under the car.
Greg
Greg
01-06-2010, 01:58 AM
#44
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you are on the right track, but its alittle misleading. the underside of the F1 car is really like an upside down wing. quite the opposite of most sports cars.
You put more air under most all sports cars, and you will create more lift, unless you can accelerate it, and then diffuse it in the rear. You can accelerate it by use of venturi tunnels, since we usually dont find the body shapes of F1 cars on sports cars.
You put more air under most all sports cars, and you will create more lift, unless you can accelerate it, and then diffuse it in the rear. You can accelerate it by use of venturi tunnels, since we usually dont find the body shapes of F1 cars on sports cars.
01-06-2010, 06:08 AM
#45
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By Mark Kibort
Mark you need to accept the bottom of an F1 car is completely flat, it is not curved at all. It has a step in it to reduce down force, if it was completely flat it would generate even more downforce. The step used to be a wooden plank. That plank would be checked for wear at the end of the race and if too worn the car disqualified. They used to use it to stop them running the car too low. The step is 50 mm currently. It was seen a safety issue.
http://www.formula1.com/inside_f1/un...port/5281.html
Please read the above link, it is not the technical regs but a an overview if you want the technical regs you need rule number 3.12. As I said it has been that way for over 20 years, there is no tunnels or anything even approaching what might be considered a tunnel or upside down wing They get their downforce from what i have been saying all along, that is a flat floor and its other associated parts running lots of air underneath the vehicle.
Now if there is anybody game to comment on this
I believe that the 599 XX incredible downforce is partly down to the bonnet vents. I suspect what is happening is that Ferrari in their wisdom duct all the engine cooling air over the top of the body instead of below it.
Just in case some don't know how a wing actually works, the top part of the wing is curved and as such it is longer in distance. The air must travel faster as such it creates a low pressure zone above it and this generates lift. It generates lift because the pressure below is greater than above.
So in a car like the Audi TT (first version) it become like a wing and takes off hence the spoiler trying to disrupt the airflow, hence the name spoiler. So if the air exiting the bonnet ducts stops this low pressure zone above the car by supplying additional air to raise the localised pressure.
This way you kill the lift being generated by the curved upperbody of the car and the underbody which is running lots of air under it but at a very fast rate, this create a localised low pressure zone and that means around a 1000 pounds of downforce at 150 mph in the case of the 599XX. That is significant amount of downforce without any actual wings or big splitters. It uses a very clever technology that breaks its wake, I am thinking that reduces drag. What are your thoughts?
I haven't gone into zero loss cooling as I think we should kick this about first, but it is gaining ground and F1 cars have been exploiting it for years. if you want to see a road style car that has it, look up the Pro-drive Ferrari 550.
This car, the 599 XX is very quick, almost as quick as the new Ferrari FFX evolution and it was quicker than the first FFX. It does that with less power than the first FFX, so that speed is down to its aero. To me that is interesting as the first FFX is no slouch.
Greg
you are on the right track, but its alittle misleading. the underside of the F1 car is really like an upside down wing. quite the opposite of most sports cars.
You put more air under most all sports cars, and you will create more lift, unless you can accelerate it, and then diffuse it in the rear. You can accelerate it by use of venturi tunnels, since we usually dont find the body shapes of F1 cars on sports cars.
You put more air under most all sports cars, and you will create more lift, unless you can accelerate it, and then diffuse it in the rear. You can accelerate it by use of venturi tunnels, since we usually dont find the body shapes of F1 cars on sports cars.
Mark you need to accept the bottom of an F1 car is completely flat, it is not curved at all. It has a step in it to reduce down force, if it was completely flat it would generate even more downforce. The step used to be a wooden plank. That plank would be checked for wear at the end of the race and if too worn the car disqualified. They used to use it to stop them running the car too low. The step is 50 mm currently. It was seen a safety issue.
http://www.formula1.com/inside_f1/un...port/5281.html
Please read the above link, it is not the technical regs but a an overview if you want the technical regs you need rule number 3.12. As I said it has been that way for over 20 years, there is no tunnels or anything even approaching what might be considered a tunnel or upside down wing They get their downforce from what i have been saying all along, that is a flat floor and its other associated parts running lots of air underneath the vehicle.
Now if there is anybody game to comment on this
I believe that the 599 XX incredible downforce is partly down to the bonnet vents. I suspect what is happening is that Ferrari in their wisdom duct all the engine cooling air over the top of the body instead of below it. Just in case some don't know how a wing actually works, the top part of the wing is curved and as such it is longer in distance. The air must travel faster as such it creates a low pressure zone above it and this generates lift. It generates lift because the pressure below is greater than above.
So in a car like the Audi TT (first version) it become like a wing and takes off hence the spoiler trying to disrupt the airflow, hence the name spoiler. So if the air exiting the bonnet ducts stops this low pressure zone above the car by supplying additional air to raise the localised pressure.
This way you kill the lift being generated by the curved upperbody of the car and the underbody which is running lots of air under it but at a very fast rate, this create a localised low pressure zone and that means around a 1000 pounds of downforce at 150 mph in the case of the 599XX. That is significant amount of downforce without any actual wings or big splitters. It uses a very clever technology that breaks its wake, I am thinking that reduces drag. What are your thoughts?
I haven't gone into zero loss cooling as I think we should kick this about first, but it is gaining ground and F1 cars have been exploiting it for years. if you want to see a road style car that has it, look up the Pro-drive Ferrari 550.
This car, the 599 XX is very quick, almost as quick as the new Ferrari FFX evolution and it was quicker than the first FFX. It does that with less power than the first FFX, so that speed is down to its aero. To me that is interesting as the first FFX is no slouch.
Greg
