Aerodynamic suction device for a C3
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Le Mans Master
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From: Brazos TX
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Aerodynamic suction device for a C3
I've been kicking the idea around for a little while of using fans to suck the air from under the car to create down force. The Chaparral 2J car used this concept in the early '70's and, more recently, the McLaren F1 super car has some sort of fan system. I haven’t run many numbers yet but the Chaparral used a 274cc two-stroke from a snowmobile to power two fans and the car was setup with aggressive skirts from just behind the front wheels running all the way to the back of the car. Much of this isn't practical for a street car but McLaren clearly made some compromises yet felt that it provided some advantage.
So I'm thinking that a 274cc two-stroke from the '70's would put out 20 or 30hp? That kind of power would be difficult to match in an electric driven fan so I wonder the power that McLaren spec'd for their fan? I think some moderate skirts would still be useful and practical for many driving situations. As I said I haven't run any numbers yet but I think calculating the total air volume running under the car at a specific speed and getting a general idea of the pressure is a good start. It really doesn't take much of a pressure differential to make some serious down force so I think the effort is worth it.
So I'm thinking that a 274cc two-stroke from the '70's would put out 20 or 30hp? That kind of power would be difficult to match in an electric driven fan so I wonder the power that McLaren spec'd for their fan? I think some moderate skirts would still be useful and practical for many driving situations. As I said I haven't run any numbers yet but I think calculating the total air volume running under the car at a specific speed and getting a general idea of the pressure is a good start. It really doesn't take much of a pressure differential to make some serious down force so I think the effort is worth it.
Melting Slicks
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From: Midland TX
The Chaparral has a floating skirt all the way around the bottom of the body so it is in contact with the ground all the time.
All the Chaparral cars are on display at the Petroleum Museum in Midland, TX if you want to see them up close and personal (plug for the hometown
)
At the grand opening of the Chaparral wing of the museum one of the drivers described driving the car...
The Chaparrals were known to use aerodynamics such as wings and body shape to create downforce. This was a departure since it created downforce just sitting still.
All the Chaparral cars are on display at the Petroleum Museum in Midland, TX if you want to see them up close and personal (plug for the hometown
)At the grand opening of the Chaparral wing of the museum one of the drivers described driving the car...
When they started the engine for the fans you could feel the car go down a couple of inches.
He said it really stuck to the track and they were able to go around corners much faster than anyone else.The Chaparrals were known to use aerodynamics such as wings and body shape to create downforce. This was a departure since it created downforce just sitting still.
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Le Mans Master
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Originally Posted by Gordonm
You would have to be doing somewhere over 100 mph for this to even make the slightest difference. Where are you going to mount these heavy "suckers"?
The fans would have to be mounted somewere in the rear of the car. I don't run a spare tire so there is a lot of room under the gas tank.
Melting Slicks
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From: Midland TX
I would think about using a front spoiler with a flexible skirt to get it low to the ground and possibly a skirt around the sides. The faster you drive you create low pressure under the car that will suck it down.
You will need to be going pretty fast for this to really be effective I would think. If you are driving autocross (from your picture) I don't think you'll get up to a high enough speed.
If you come up with a vacuum setup please post pics. That will be interesting to see.
BTW - they have / had an interesting display at the museum showing how much tighter a model car can turn using the vacuums.
You will need to be going pretty fast for this to really be effective I would think. If you are driving autocross (from your picture) I don't think you'll get up to a high enough speed.
If you come up with a vacuum setup please post pics. That will be interesting to see.
BTW - they have / had an interesting display at the museum showing how much tighter a model car can turn using the vacuums.
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Le Mans Master
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72vette_454, I'm hoping to visit the museum sometime. No offense but the Chaparrals and the CAF are the only reasons I would visit Midland. It's a long way from nothing out there. I may have a road trip to AZ and CA within the year so I may get a chance to stop by.
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Le Mans Master
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Actually, the beauty of a fan system is that it works much better at low speed than a conventional aero undertray which relies on air movement in order to generate down force. I mainly run track events but it would definitely work for autoX as well (it would just be illegal). That model car display sounds cool.
Melting Slicks
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From: Midland TX
Originally Posted by burners
No offense but the Chaparrals and the CAF are the only reasons I would visit Midland. It's a long way from nothing out there.
You need to come out here in October to the CAF airshow. They bring in lots of WWII warbirds and the show is awesome.
The good thing about living out here is there are plenty of open roads to drive. Going down to Big Bend area this weekend - great curves and mountains (that's what we call them anyways). Highest elevation is over 6,000 ft (highest road in Texas).
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Le Mans Master
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Mountains, haha. That's a good joke. It should be a great weekend for cruising, have fun. I had forgotten about the big airshow they have...maybe. Is the Petroleum Museum open on Sunday?
Melting Slicks
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From: Midland TX
Yep - 2 PM to 5PM
http://www.petroleummuseum.org/
Click on Chaparral Gallery for the cars. They have a pretty cool portion of a DVD available - good race footage from the 60s.
http://www.petroleummuseum.org/
Click on Chaparral Gallery for the cars. They have a pretty cool portion of a DVD available - good race footage from the 60s.
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St. Jude Donor '09
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Le Mans Master
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Yeah, those Can-Am cars are awesome! Good photo, Jughead. Doesn't it look like something from Star Wars? I don't want to do anything that obtuse but I think a compromise can be figured out.
Cool, open on Sunday. That could work out well.
Cool, open on Sunday. That could work out well.
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St. Jude Donor '05-'07
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Le Mans Master
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That's cool! It could be very handy in rush hour traffic or if the elevator is full..."no problem, I'll take the Vette and meet you upstairs."
