Okay... i'm sure that there is an answer immediately for this but it still has me thinking.
Everytime I see wind tunnel testing it is about the air passing over the front of the car... which is fair enough because that's generally the direction of the flow.
BUT
When the car is turning the air flow is not passing over the front of the car. So is there scope for aero improvement from the side of an F1 car or would any improvements at those angles detract massively from normal straight aero enhancements?
Wind Tunnel Testing
Started by
f1paddocks
, Aug 24 2011 21:35
6 replies to this topic
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#2
Spoofski
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Posted 24 August 2011 - 21:46
Wind tunnel testing at a variety of yaw angles has been pretty much commonplace in F1 for a few years now (5+ years if I remember correctly).
#3
cheapracer
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Posted 25 August 2011 - 01:14
As crude as Sprintcar wings look they are of course designed to catch air in severe yaw (sideways) and straighten the car up. When I first saw the Williams 'Walrus Nose' I wondered if it wouldn't create drag and understeer for the same reason but apparently it was very effective.
#4
mariner
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Posted 25 August 2011 - 07:13
A sprint car wing also generates a rolling moment opposed tot he cornering force roll force as the big end fence on the inside applies a load inwards. Illustated here
http://padirtreport....a_4-13-06_1.jpg
http://padirtreport....a_4-13-06_1.jpg
#5
gruntguru
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Posted 25 August 2011 - 10:57
Not only a moment but also a substantial lateral force helping the car around the corner. When tyre coefficient of friction is less than 1.0 it is more efficient for the available aero force to be used laterally (not usually feasible of course) than to add it to the tyre normal force. With u>1.0 of course the reverse is true.
#6
Allan Lupton
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Posted 06 September 2011 - 14:06
Don't forget that the most important aerodynamic yaw case is in a cross-wind no matter what the car is doing (cornering/straight line accelerating/braking).
It is most important because in principle it is there most of the time. Too much weathercock stability would make the vehicle difficult to control on a straight in a variable cross-wind - which is only a steady cross-wind interrupted by walls, grandstands, high ground, etc.
We used to have that problem with road cars when the centre of gravity and the sideways centre of pressure were well separated - e.g. on Volkswagens which required, in the words of a colleague who had one, "a bit of weather helm" and probably it was the same on other rear-engined cars. That at least (steering into the wind) was instinctive but you needed "lee helm" for the early front-drivers such as the Citroen Big 15 and the Six.
It is most important because in principle it is there most of the time. Too much weathercock stability would make the vehicle difficult to control on a straight in a variable cross-wind - which is only a steady cross-wind interrupted by walls, grandstands, high ground, etc.
We used to have that problem with road cars when the centre of gravity and the sideways centre of pressure were well separated - e.g. on Volkswagens which required, in the words of a colleague who had one, "a bit of weather helm" and probably it was the same on other rear-engined cars. That at least (steering into the wind) was instinctive but you needed "lee helm" for the early front-drivers such as the Citroen Big 15 and the Six.
#7
bigleagueslider
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Posted 10 September 2011 - 01:00
f1paddocks,
Wind tunnel testing is the opposite of what a car experiences on the track. That is, in tunnel testing the air moves past the car, while on the track the car moves through the air. A small but important difference.
While you mentioned yaw effects, there are also pitch,roll, ground, and wall effects to consider in tunnel testing. In sub-scale tunnels, the model is usually mounted on a set of balances that measure the aero forces produced. These balances can be articulated to vary roll, pitch, and yaw. Some tunnels also use a moving ground plane, or rolling road surface, to simulate the underbody ground effects, and spinning tires to evaluate their aero effects. And to get even more realistic test results, a tunnel model might even pipe compressed air thru the model's exhaust system to validate the impact of these flows.
Transonic aircraft wind tunnels are the most complex of all. These sub-scale, blow-down tunnels sometimes use exotic gas mixtures instead of air to correct for Reynolds number effects.
Interesting topic.
slider
Wind tunnel testing is the opposite of what a car experiences on the track. That is, in tunnel testing the air moves past the car, while on the track the car moves through the air. A small but important difference.
While you mentioned yaw effects, there are also pitch,roll, ground, and wall effects to consider in tunnel testing. In sub-scale tunnels, the model is usually mounted on a set of balances that measure the aero forces produced. These balances can be articulated to vary roll, pitch, and yaw. Some tunnels also use a moving ground plane, or rolling road surface, to simulate the underbody ground effects, and spinning tires to evaluate their aero effects. And to get even more realistic test results, a tunnel model might even pipe compressed air thru the model's exhaust system to validate the impact of these flows.
Transonic aircraft wind tunnels are the most complex of all. These sub-scale, blow-down tunnels sometimes use exotic gas mixtures instead of air to correct for Reynolds number effects.
Interesting topic.
slider
