How is it two slightly different cars, but designed to be raced in the same year, same series, can have very different aero changes when at say 5 degrees yaw? One loses front downforce and gains rear downforce, while the other gains front downforce and loses rear downforce...
I always thought in yaw, both ends would lose downforce since wings are designed to work best with airflow going straight across them like designed, no? I can understand one end losing more downforce than the other in yaw, but I would never have expected an actual gain at one end. How does that occur?
Gaining downforce in yaw
Started by
shaun979
, Nov 04 2006 21:50
5 replies to this topic
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#2
Supercar
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Posted 04 November 2006 - 22:20
Which cars and series are you referring to?
I know the current Le Mans prototypes have a spec underbody between the front and rear wheels with the diffuser (tunnels) being fed partially from under the car's sides in front of the rear wheels. If the car gets sideways then that diffuser gets more air.
Also, that underbody between the front the rear wheels it tapered, like a boat, with the sides being higher than the center. The underbody does not produce much downforce when the car is going straight, but if the car gets sideways then it works like one huge ground effect tunnel.
The front diffuser, on the other hand, is the most efficient only when the car is going straight. It gets less air if the car gets sideways. So when the car gets sideways, the center of the downforce moves to the back.
I know the current Le Mans prototypes have a spec underbody between the front and rear wheels with the diffuser (tunnels) being fed partially from under the car's sides in front of the rear wheels. If the car gets sideways then that diffuser gets more air.
Also, that underbody between the front the rear wheels it tapered, like a boat, with the sides being higher than the center. The underbody does not produce much downforce when the car is going straight, but if the car gets sideways then it works like one huge ground effect tunnel.
The front diffuser, on the other hand, is the most efficient only when the car is going straight. It gets less air if the car gets sideways. So when the car gets sideways, the center of the downforce moves to the back.
#3
mulsannemike
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Posted 05 November 2006 - 15:07
Originally posted by Supercar
Which cars and series are you referring to?
I know the current Le Mans prototypes have a spec underbody between the front and rear wheels with the diffuser (tunnels) being fed partially from under the car's sides in front of the rear wheels. If the car gets sideways then that diffuser gets more air.
Also, that underbody between the front the rear wheels it tapered, like a boat, with the sides being higher than the center. The underbody does not produce much downforce when the car is going straight, but if the car gets sideways then it works like one huge ground effect tunnel.
The front diffuser, on the other hand, is the most efficient only when the car is going straight. It gets less air if the car gets sideways. So when the car gets sideways, the center of the downforce moves to the back.
LMP cars do indeed produce a good amount of downforce in a straight line, the underbody chamfer simply allows the tunnels to continue producing downforce in yaw as the typical condition is to loose a substantial amount when a car spins.
#4
dead_eye
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Posted 05 November 2006 - 19:24
it all depends on wether the designers built the system to provide downforce when the cars not facing the air head on.
One well known system is the 2006 scoobie wrc wing, the large cf plates running from under the top edge downt to the boot create a near solid wall of resitance to the air when the angle of approach is right. Thus when you kick the back end out the air is hitting the wing side on or diagonally and pushing the back of the car straight again.
Ground force systems work in the same way but have to be designed carefully, if the car gains a lot downforce on to the leading side of the car it its more likely to dig in and roll the car so even side to side distribution is essential.
About a year ago i was honoured enough to view a very special private car (non competetive) built by gpB fan that wanted to see just what was possible with no restrictions now technologies moved on.
All the top and side aero parts were mounted to either electrical or hydraulic rams and controlled via a trick ecu that read g force, wheel speed etc. When it sensed the back end was out by say 25 degrees to the drivers side it lowered the the wing, skirt, front spoiler etc to the right hand side so the air was pushing the trailing side of the car down. it also changed the aero setup on the move with increasing speed etc.
I never had a chance to see it running but the owner assures me it provides phenomenal amounts of grip and confidence at stupidly high speeds even when broadside on. It was still in development stages at the time with a lot of other new and formula 1 technology so god only knows what its capable of know!
One well known system is the 2006 scoobie wrc wing, the large cf plates running from under the top edge downt to the boot create a near solid wall of resitance to the air when the angle of approach is right. Thus when you kick the back end out the air is hitting the wing side on or diagonally and pushing the back of the car straight again.
Ground force systems work in the same way but have to be designed carefully, if the car gains a lot downforce on to the leading side of the car it its more likely to dig in and roll the car so even side to side distribution is essential.
About a year ago i was honoured enough to view a very special private car (non competetive) built by gpB fan that wanted to see just what was possible with no restrictions now technologies moved on.
All the top and side aero parts were mounted to either electrical or hydraulic rams and controlled via a trick ecu that read g force, wheel speed etc. When it sensed the back end was out by say 25 degrees to the drivers side it lowered the the wing, skirt, front spoiler etc to the right hand side so the air was pushing the trailing side of the car down. it also changed the aero setup on the move with increasing speed etc.
I never had a chance to see it running but the owner assures me it provides phenomenal amounts of grip and confidence at stupidly high speeds even when broadside on. It was still in development stages at the time with a lot of other new and formula 1 technology so god only knows what its capable of know!
#5
shaun979
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Posted 05 November 2006 - 22:02
Originally posted by Supercar
Which cars and series are you referring to?
Dallara IR3-6 vs Panoz G-force cars - IRL Indy Car Series.
This was off high speed full scale static-ground-plane wind tunnel tests, but is also backed up by driver feedback and data from track testing from more than one team.
#6
mulsannemike
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Posted 12 November 2006 - 03:44
I'd be curious as to who generated that IRL data.
