Splitter design function and effects. Experience, Design knowledge?
08-21-2009, 01:44 PM
#76
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No, to clarify, you cited Knots and I converted them to MPH. The fastest straight line speed recorded with an F1 car in a race was 220 MPH. Converting to knots as was your original premise is 191 Knots not MPH. You see, you need to keep your eyes on the details. That is where the devil is.
08-21-2009, 01:44 PM
#77
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"Main qualification" Exhibit A
"Main qualification" Exhibit B
So, in the interest of preserving your racing career, dontcha think you might want to take those videos down?
As my 5th grade teacher used to say: "A word to the wise is always sufficient."
08-21-2009, 01:44 PM
#78
In my case I was involved with design as well and spent a good deal of time in working the lab working with the test equiment to proving design ideas.
Now, what is relevant, is that I'm bringing basic concepts to the table with some imperical tesing results. Lets focus on those.
If you have found any errors of my analysis or the review of the basic theories, I think we would all like to see them. After all, it helps us all, if we are trying to make progress with our cars in the areas of aero.
Now, what is relevant, is that I'm bringing basic concepts to the table with some imperical tesing results. Lets focus on those.
If you have found any errors of my analysis or the review of the basic theories, I think we would all like to see them. After all, it helps us all, if we are trying to make progress with our cars in the areas of aero.
As you are tirelessly pointing out, you are driving a 20 year old underpowered car with worn-out bushings, worn out old tires and inadequate suspension. It seems you would get much more benefit from bringing your car up to a safe, race ready and competitive level before you worry about how F1 aerodynamics do not apply to your vehicle...
I raced with you at Buttonwillow and did not witness anything that lead me to believe that F1 engineers could learn anything from you...
But of course, this is the internet and not a real world race track!
What a joke!
08-21-2009, 01:50 PM
#79
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All this time, effort, and rhetoric to improve the aero on a car with sub-optimal mechanical grip? How about using some of this time to shop for new tires?
08-21-2009, 01:57 PM
#80
Thanks for the post. thost are some great shots! That is something I havent thought about. using defuser ducts to further aid brake cooling ( i have a couple of small defuser ducts that come stock on the 928 for brake cooling ) The concept is to grab the air that does end up under the car and put it to work, and then get rid of it to the sides. Ive already got the 944GTR type side fender openings from discussions in other threads, mainly for fitting larger tires up front. Now, I find that there is a big advantage, probably near as good as the hood vent for adding downforce and adding brake cooling as well.
The diffusers are there to make downforce...
Read this
http://www.mulsannescorner.com/ToyotaEagleMkIII-2.html
08-21-2009, 01:58 PM
#81
A technical thread based on assumptions that are speculative at best doesn't help anyone who comes to the board looking to understand more about a given topic. Sunday makes the point well, despite being shouted down by more speculative rambling.
As a caveat, I spent years racing sailplanes and have a couple of engineering degrees. I know a little fluid dynamics theory, and a fair bit about low speed aerodynamics. This is enough for me to stipulate that things are not always as they might appear. Sundays point about laminar flow is absolutely right, and this plus boundary layer effects make what might appear to be reasonable assumptions on first principles [eg differential pressure effects from simple flow over an airfoil] are often wrong.
As with most of these topics, saying it ten times won't make it any less wrong. What it will do is lead some readers to buy into the false logic. Say something wrong enough times and some segment of the audience will believe it. It must be hard for the mods to deal with, but I'd like to see threads like this one deleted. They do more harm than good.
As a caveat, I spent years racing sailplanes and have a couple of engineering degrees. I know a little fluid dynamics theory, and a fair bit about low speed aerodynamics. This is enough for me to stipulate that things are not always as they might appear. Sundays point about laminar flow is absolutely right, and this plus boundary layer effects make what might appear to be reasonable assumptions on first principles [eg differential pressure effects from simple flow over an airfoil] are often wrong.
As with most of these topics, saying it ten times won't make it any less wrong. What it will do is lead some readers to buy into the false logic. Say something wrong enough times and some segment of the audience will believe it. It must be hard for the mods to deal with, but I'd like to see threads like this one deleted. They do more harm than good.
08-21-2009, 02:03 PM
#82
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When did you race me at buttonwillow? 10 years ago??? (I havent raced at buttonwillow in the last 10 years. Actually, one time when I first got the Holbert car after slapping it together in a month with no modifications and very used tires. (very used hoosiers) 
Again, the changes most of make, do make our cars safer. Im not sure the changes and use of wings and splitters are good for more than fine tuning (small gains on the track we visit in Nor cal due to the speed of the turns and straights) To this date, ive run my fastest time at a handling track with out the use of refined aero adders. (Ill see if that changes next weekend with the addition to the splitter mods) In fact, starting out, most had caused more problems then they solved. In the end, there are gains, but most of fun is finding the balance to them.
Again, the changes most of make, do make our cars safer. Im not sure the changes and use of wings and splitters are good for more than fine tuning (small gains on the track we visit in Nor cal due to the speed of the turns and straights) To this date, ive run my fastest time at a handling track with out the use of refined aero adders. (Ill see if that changes next weekend with the addition to the splitter mods) In fact, starting out, most had caused more problems then they solved. In the end, there are gains, but most of fun is finding the balance to them.
Mark,
As you are tirelessly pointing out, you are driving a 20 year old underpowered car with worn-out bushings, worn out old tires and inadequate suspension. It seems you would get much more benefit from bringing your car up to a safe, race ready and competitive level before you worry about how F1 aerodynamics do not apply to your vehicle...
I raced with you at Buttonwillow and did not witness anything that lead me to believe that F1 engineers could learn anything from you...
But of course, this is the internet and not a real world race track!
What a joke!
As you are tirelessly pointing out, you are driving a 20 year old underpowered car with worn-out bushings, worn out old tires and inadequate suspension. It seems you would get much more benefit from bringing your car up to a safe, race ready and competitive level before you worry about how F1 aerodynamics do not apply to your vehicle...
I raced with you at Buttonwillow and did not witness anything that lead me to believe that F1 engineers could learn anything from you...
But of course, this is the internet and not a real world race track!
What a joke!
08-21-2009, 02:07 PM
#83
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Thread Starter
The tires I use seem to be ok for guys to run 2:14 at road america and 1:28.xx at Laguna, but it would be nice to have their power! (and latest technology)
The key thing is getting sub-opitmal tires to work and learn about the effects of aero changes. Then, when we get on something better, it will pay bigger dividends. Now, you realize im using some very good hoosiers for sears next weekend and near new hoosiers for the last race of the season at laguna. (SCCA race where a lot of SpeedGT racers will be using it as a tune up race before their event in Oct)
mk
The key thing is getting sub-opitmal tires to work and learn about the effects of aero changes. Then, when we get on something better, it will pay bigger dividends. Now, you realize im using some very good hoosiers for sears next weekend and near new hoosiers for the last race of the season at laguna. (SCCA race where a lot of SpeedGT racers will be using it as a tune up race before their event in Oct)
mk
08-21-2009, 02:08 PM
#84
When did you race me at buttonwillow? 10 years ago??? (I havent raced at buttonwillow in the last 10 years. Actually, one time when I first got the Holbert car after slapping it together in a month with no modifications and very used tires. (very used hoosiers)
Again, the changes most of make, do make our cars safer. Im not sure the changes and use of wings and splitters are good for more than fine tuning (small gains on the track we visit in Nor cal due to the speed of the turns and straights) To this date, ive run my fastest time at a handling track with out the use of refined aero adders. (Ill see if that changes next weekend with the addition to the splitter mods) In fact, starting out, most had caused more problems then they solved. In the end, there are gains, but most of fun is finding the balance to them.
Again, the changes most of make, do make our cars safer. Im not sure the changes and use of wings and splitters are good for more than fine tuning (small gains on the track we visit in Nor cal due to the speed of the turns and straights) To this date, ive run my fastest time at a handling track with out the use of refined aero adders. (Ill see if that changes next weekend with the addition to the splitter mods) In fact, starting out, most had caused more problems then they solved. In the end, there are gains, but most of fun is finding the balance to them.
All the pro stickers looked good on your car, though
08-21-2009, 02:10 PM
#85
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First, the splitter is NOT plywood, those are just skidplates (which sometimes are mandated to get ride height and allow for when they scrap on some turns...you don't want carbon shards splintering the track!).
Second, many GT cars and almost all LMP style cars have front diffusers built into the undertray/splitters, as seen here. Think of the rear diffuser but under the front of the car pointing into the wheel well area. Also worth noting the leading edge curvature, as well as the overall girth of the splitter.
Second, many GT cars and almost all LMP style cars have front diffusers built into the undertray/splitters, as seen here. Think of the rear diffuser but under the front of the car pointing into the wheel well area. Also worth noting the leading edge curvature, as well as the overall girth of the splitter.
Yes, I have been following some of the racing rags in the aero area.
I dont reallly understand what you are talking about, as far as "defuser" in front of the wheel. there is a high pressure zone in the wheel well, and there are two things that Ive seen done. vent the fender at the low pressure area on the top of the fender, AND vent the rear of the fender, just in front of the door. I havent done the hole cuts until I measure a significant amount of pressure build up there.
explain a "defuser " in the front of the car. as far as I know, that means taking an area of low pressure and venting it out to higher pressure, as is done in the rear of most race cars now.
Now as far as a splitter up front, it is just that. Not a wing, it separates two flow and pressure zones. you dont need thick, but it helps for stability, strength and its ability to be integrated into the undertray.
I dont reallly understand what you are talking about, as far as "defuser" in front of the wheel. there is a high pressure zone in the wheel well, and there are two things that Ive seen done. vent the fender at the low pressure area on the top of the fender, AND vent the rear of the fender, just in front of the door. I havent done the hole cuts until I measure a significant amount of pressure build up there.
explain a "defuser " in the front of the car. as far as I know, that means taking an area of low pressure and venting it out to higher pressure, as is done in the rear of most race cars now.
Now as far as a splitter up front, it is just that. Not a wing, it separates two flow and pressure zones. you dont need thick, but it helps for stability, strength and its ability to be integrated into the undertray.
08-21-2009, 02:12 PM
#86
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This is about the most valuable post in this entire thread.
Mark, do yourself a favor..... go out and buy a new set of race tires and your times will drop much faster than any homemade splitter/wing, helicoptor tape or diffuser you would ever make on your own. Seriously...
08-21-2009, 02:14 PM
#87
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08-21-2009, 02:15 PM
#88
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You know what? I'm sorry I got caught up in this Mark Kibort VORTEX (pun intended).
This is about the most valuable post in this entire thread.
Mark, do yourself a favor..... go out and buy a new set of race tires and your times will drop much faster than any homemade splitter/wing, helicoptor tape or diffuser you would ever make on your own. Seriously...
This is about the most valuable post in this entire thread.
Mark, do yourself a favor..... go out and buy a new set of race tires and your times will drop much faster than any homemade splitter/wing, helicoptor tape or diffuser you would ever make on your own. Seriously...
08-21-2009, 02:17 PM
#89
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In the case of some modern prototype cars, the front splitter really IS an air foil, with air flow above and below it and an adjustable angle of attack. There was much discussion about that during the coverage of LeMans this year.
Your "yes, right on" quote is in response to this:
At the front of the car there is the stagnation point. This is the point where the air velocity goes to 0 and the pressure becomes highest (stagnation pressure). This point is located somewhere on the front bumper/airdam. Remember that pressure acts in all directions. By placing a horizontal sheet underneath the stagnation point, the high pressure that is in this area acts on top of the splitter. This creates downforce. You can approximate stagnation pressure by 0.5*density*velocity^2. Take this stagnation pressure and multiply it by the plan view area of your splitter to get a ballpark of the force on the top of the splitter (this assumes atmospheric pressure underneath the splitter - see below).
Additionally, the splitter helps to create low pressure underneath it by forcing the airflow into a narrow gap between the road and the car. By forcing the air through the gap the speed increases. Net effect is you have high pressure above the splitter and low pressure below. However, the pressure below is very dependent on what the bottom side of the car looks like downstream of the splitter...
Basically the splitter is just using the high pressure that already exists at the stagnation point in front of the car and turning it into a downward force. To take full advantage of, and create low pressure underneath requires much more careful consideration.
Either way - putting on a splitter is a very easy way to pick up appreciable front downforce. The bigger the planview area the more downforce. It does not have a significant effect on drag until you start making it ridiculously long. A rule of thumb for a "big" splitter is they usually extend 3-6" beyond the front bumper looking from the top.
Additionally, the splitter helps to create low pressure underneath it by forcing the airflow into a narrow gap between the road and the car. By forcing the air through the gap the speed increases. Net effect is you have high pressure above the splitter and low pressure below. However, the pressure below is very dependent on what the bottom side of the car looks like downstream of the splitter...
Basically the splitter is just using the high pressure that already exists at the stagnation point in front of the car and turning it into a downward force. To take full advantage of, and create low pressure underneath requires much more careful consideration.
Either way - putting on a splitter is a very easy way to pick up appreciable front downforce. The bigger the planview area the more downforce. It does not have a significant effect on drag until you start making it ridiculously long. A rule of thumb for a "big" splitter is they usually extend 3-6" beyond the front bumper looking from the top.
I'm not sure that's really the way a splitter "works". Splitters do act as a wing, by creating a low pressure area underneath and a high pressure area on top. Some good basic info here:
http://www.e30m3project.com/e30m3per...r/splitter.htm
http://www.e30m3project.com/e30m3per...r/splitter.htm
YES! And those defusers in the front are used for pushing air to the wheel areas for cooling. if vented out to the wheel well or fender rear vents, it also increases downforce even more by taking the air that has reached under the car, and routes it to the wheels and sides.
08-21-2009, 02:19 PM
#90