Car aero development
09-24-2009, 11:13 AM
#126
Beautiful work guys, I like the clean metalwork in particular, I also wish I had a bender.
Not entirely accurate. Diffusers are intended to smooth airflow out the back. They are supposed to be tilted up (start lower in front, exit higher in back) to promote less turbulence behind the car. The fins are to route the air underneath the car straight out the back, instead of letting it leak out the sides, in part promoting a venturi effect to pull the car down against the ground. This obviously has the greatest effect when combined with other aero pieces to make sure that what little air that does get underneath does so in a controlled manner (you want less air under the car, hence lip spoilers, etc, and what does get under the car you don't want leaking in our out across the sides) Wheels typically are the biggest problem.
At any rate, yes, all of this stuff is more effective closer to the ground (not really for cleaner air aspects, but rather less air and less space for it to leak in/out), but the angle of the rear diffuser is quite important, and should be angled up (I forget, I think the ideal is between 20 and 30 degrees from horizontal. Incidentally the reason there is 'ideal' angle (although it is somewhat dependent on the shape of the car) is to join the upper and lower airflows as efficiently as possible, without having the air seperate from the face of the diffuser (if it is too steep). If the angle is too shallow, it does straighten air out the back, but it doesn't help the air up to join in with the stream of air coming down from the top (which results in a dirtier wake behind the car). Practically you typically have to make the diffuser fit as best you can and get as close to the ideals as possible because you already have design constraints from the car that you have to work in (not everyone gets to design F1 cars).
no offense and it does look great, but it seems as if it would be even more functional if you lower the diffusers to where its more even with the ground and gets cleaner air. and btw cueball, diffusers arent supposed to have much angle but rather leveled with the ground so it could be argued that for a miata yours may work better. Diffusers are adjustable anyways so the pass will probably lower them at the track if he pleases. the elise and exiges are just lower to where the fins will catch air before anything else so thats why they have a slight angle
At any rate, yes, all of this stuff is more effective closer to the ground (not really for cleaner air aspects, but rather less air and less space for it to leak in/out), but the angle of the rear diffuser is quite important, and should be angled up (I forget, I think the ideal is between 20 and 30 degrees from horizontal. Incidentally the reason there is 'ideal' angle (although it is somewhat dependent on the shape of the car) is to join the upper and lower airflows as efficiently as possible, without having the air seperate from the face of the diffuser (if it is too steep). If the angle is too shallow, it does straighten air out the back, but it doesn't help the air up to join in with the stream of air coming down from the top (which results in a dirtier wake behind the car). Practically you typically have to make the diffuser fit as best you can and get as close to the ideals as possible because you already have design constraints from the car that you have to work in (not everyone gets to design F1 cars).
Last edited by elsdragon314; 09-24-2009 at 11:21 AM. Reason: clarify ideal angle
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09-24-2009, 11:17 AM
#127
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The HIDs arent miata specific. I just found a kit with the bulbs, ballasts, and metal clips and used them to connect to the stock miata headlight connectors. Then I integrated them into the turn signal lens. If you constantly drive your car on the street you really shouldnt do this since you will no longer have turn signals. Do this at your own expense. I just thought it would be cool for when racing to have the HIDs on and flash someone in front of me to let em know im there and ready to pass. Im sure they'll find something in the handbook to stop me from doing it, but the lights stay on. Im planning on making a pictoral mounting/install thread for them soon so that shouldnt be too far off.
Last edited by Sam Amporful; 09-24-2009 at 11:55 AM.
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09-24-2009, 11:25 AM
#128
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Beautiful work guys, I like the clean metalwork in particular, I also wish I had a bender.
Not entirely accurate. Diffusers are intended to smooth airflow out the back. They are supposed to be tilted up (start lower in front, exit higher in back) to promote less turbulence behind the car. The fins are to route the air underneath the car straight out the back, instead of letting it leak out the sides, in part promoting a venturi effect to pull the car down against the ground. This obviously has the greatest effect when combined with other aero pieces to make sure that what little air that does get underneath does so in a controlled manner (you want less air under the car, hence lip spoilers, etc, and what does get under the car you don't want leaking in our out across the sides) Wheels typically are the biggest problem.
At any rate, yes, all of this stuff is more effective closer to the ground (not really for cleaner air aspects, but rather less air and less space for it to leak in/out), but the angle of the rear diffuser is quite important, and should be angled up (I forget, I think the ideal is between 20 and 30 degrees from horizontal.)
Not entirely accurate. Diffusers are intended to smooth airflow out the back. They are supposed to be tilted up (start lower in front, exit higher in back) to promote less turbulence behind the car. The fins are to route the air underneath the car straight out the back, instead of letting it leak out the sides, in part promoting a venturi effect to pull the car down against the ground. This obviously has the greatest effect when combined with other aero pieces to make sure that what little air that does get underneath does so in a controlled manner (you want less air under the car, hence lip spoilers, etc, and what does get under the car you don't want leaking in our out across the sides) Wheels typically are the biggest problem.
At any rate, yes, all of this stuff is more effective closer to the ground (not really for cleaner air aspects, but rather less air and less space for it to leak in/out), but the angle of the rear diffuser is quite important, and should be angled up (I forget, I think the ideal is between 20 and 30 degrees from horizontal.)
Last edited by Sam Amporful; 09-24-2009 at 11:42 AM.
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09-24-2009, 11:30 AM
#129
The HIDs arent miata specific. I just found a kit with the bulbs, ballasts, and metal clips and used them to connect to the stock miata headlight connectors. Then I integrated them into the turn signal lens. If you constantly drive your car on the street you really shouldnt do this since you will no longer have turn signals, will have poor dispersion of light to see where you are going, and will blind the crap out of everyone else because of complete lack of cutoff. Do this at your own expense. I just thought it would be cool for when racing to have the HIDs on and flash someone in front of me to let em know im there and ready to pass. Im planning on making a pictoral mounting/install thread for them soon so that shouldnt be too far off.
Fixed
some info to read up on if you are interested:
HiDPlanet.com :: Log in
they have a lot of useful resources and knowledge about retrofitting nice projectors in, and the benefits of particular setups.
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09-24-2009, 11:32 AM
#130
I understand that I wasnt too clear in that post now. I was referring to the fins. They usually should be as close to linear with the ground as you could get em. The actual panel should be angled thus the reason why its usually already made to be angled with the fins extending toward the floor in a linear fashion. It all depends on the cars stance and angle of attack really
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09-24-2009, 11:54 AM
#131
Curious if the big hp silver car experimented with the positioning of those VG's on the roof. Placed at the tail edge of the HT seems the natural position but others have suggested there is more benefit further forward. Just wondering if the positioning was instinct or if some work went into it.
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09-24-2009, 12:12 PM
#132
The HIDs arent miata specific. I just found a kit with the bulbs, ballasts, and metal clips and used them to connect to the stock miata headlight connectors. Then I integrated them into the turn signal lens. If you constantly drive your car on the street you really shouldnt do this since you will no longer have turn signals. Do this at your own expense. I just thought it would be cool for when racing to have the HIDs on and flash someone in front of me to let em know im there and ready to pass. Im sure they'll find something in the handbook to stop me from doing it, but the lights stay on. Im planning on making a pictoral mounting/install thread for them soon so that shouldnt be too far off.
reason i am so interested is, because i was thinking about doing this with the jdm rx7 lenses custom fit into my bumper, because i have seen many fd's in japan with this conversion, turn signal and everything.
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09-24-2009, 12:48 PM
#133
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Curious if the big hp silver car experimented with the positioning of those VG's on the roof. Placed at the tail edge of the HT seems the natural position but others have suggested there is more benefit further forward. Just wondering if the positioning was instinct or if some work went into it.
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09-24-2009, 01:29 PM
#134
It was most likely instinct on his part. They tested at Roebling the next weekend and the car was no longer unsteady under hard highspeed braking and they could corner with much more confidence so im guessing that its functional where it sits. I would love for them to do actual specific tests with it. I may try to convince him as he too likes running tests to see results.
The overall point is to achieve flow that 'sticks' to the car as much as possible for as long as possible to reduce large scale turbulence at the tail. Laminar flow can't stick to a very steep incline, but small turbulence allows flow to 'stick' to a more agressive slope, and continue a little further until it falls into large scale tumbling of the air. Prior to the actual drop off at the back of the HT, you don't need to worry about it, and you don't want the little bit of tumbling until it is necessary (as it also grows, and causes more drag). That being said, shifting it inches forward might make a difference. Difficult to quantify, probably the best way to see the difference would be taping strings on it to see how far down large scale turbulence occured.
(If you are interested, that is a partial explanation of dimples on a golf ball too, although reynolds number comes into play, so it really depends on how fast the golf ball is moving, of course people can only smack the thing but so hard... I digress)
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10-21-2009, 03:51 AM
#136
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I thought these were decent diffuser pics so I decided to post them. Kinda a waste of time but I think they're nice. After a long wait, the splitter had been delivered and the apr wing comes in from 949 on fri.
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11-01-2009, 10:04 AM
#139
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I blame some of it on the angle. Its sealed. The sideplates are alittle longer than they should be and when I cut them to size it wasnt exactly right, and I have them pulled up to far. If I lower it just a little it might fix that. I didnt catch it till now, i'll do that later.
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