Interesting Approach to Lower Lap Times
04-21-2009, 01:35 PM
#1
Still plays with cars.
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Interesting Approach to Lower Lap Times
04-21-2009, 02:30 PM
#4
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2seconds a lap? I find that very hard to believe. I'd need to see it with a pro driver(I've talked that the guy driving before, but as far I know he's not a pro, but maybe he is) and on 5 or so different cars for the results to mean anything.
04-21-2009, 03:20 PM
#7
Drifting
yup, the change in lap times could be due to higher afternoon temps, # of heatcycles on tires, wind, fuel load, and about a million other variables
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04-21-2009, 03:25 PM
#8
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Aircraft manufacturers know all about the effect and use vortex generators, winglets etc. to achieve the same result.
Joe, I suspect that the kind of wind tunnel you'd need to produce valid results is beyond the reach of these guys. Ideally an F1 or NASCAR style set up would be needed. Also much bucks to rent it and the staff to instrument and run the test.
I also agree that the track test is a little questionable in terms of consistent results. Without going to a full wind-tunnel, a simple coast-down test would help determine drag reduction but the effects would be greatly reduced as the vehicle slows since drag is a 3rd power exponent.
I think the idea is neat and at worst it will prevent stone chips
Joe, I suspect that the kind of wind tunnel you'd need to produce valid results is beyond the reach of these guys. Ideally an F1 or NASCAR style set up would be needed. Also much bucks to rent it and the staff to instrument and run the test.
I also agree that the track test is a little questionable in terms of consistent results. Without going to a full wind-tunnel, a simple coast-down test would help determine drag reduction but the effects would be greatly reduced as the vehicle slows since drag is a 3rd power exponent.
I think the idea is neat and at worst it will prevent stone chips
04-21-2009, 03:33 PM
#9
Race Director
Bob,
One other way to test is to run in high speed bowl and seek top speed. Aslong as you re not redline limited you should be able to see a difference if you control the other factors as much as possible. even so wind tunnel is the real test.
BTW... will that the effort F1 puts in why have I never seen an F1 or ALMS prototype car with these?
One other way to test is to run in high speed bowl and seek top speed. Aslong as you re not redline limited you should be able to see a difference if you control the other factors as much as possible. even so wind tunnel is the real test.
BTW... will that the effort F1 puts in why have I never seen an F1 or ALMS prototype car with these?
04-21-2009, 04:27 PM
#11
Rennlist Member
These guys are all wet. If the car was controled by control surfaces like an airplane, I would buy it. The reason that golf ***** fly farther, is that they have more control with the dimples., they are not more aerodynamic. (as I understand it).
Vortex generators on wings allow for the creation of small turbulence so that the air flow over the wing stays attached and that air can still effect the trailing edge of the wing control surfaces. (AT the cost of higher drag, but its worth it for the extra control you get for it.) Normally, when a wing starts to stall, the separation creates drag and the control surfaces now dont have air moving over them. vortex generators create a turbulence that keeps the flow attached to the wing surface, even though it is now very "disturbed" yet flowing over the control surfaces.
If this was some novel idea that works, all planes would be wrapped , or made with dimples. after all, I think Boeing has a few wind tunnels to work with
2 seconds faster a lap??? com'mon! you could get a rough drag number for the car at 100mph lets say. It might be 50lbs of force to drive the drag alone. If you removed ALL of the drag entirely, that would be like 50hp at that speed, (and any slower less, any faster more) Then, would 50hp give you 2 seconds a lap? probably not, and the reduction of drag, if any , is no where near eliminating all the drag.
Now, all they need to do is get a drag coeficient value at a wind tunnel and be done with the experiment. all these things are very easy to calculate once you have the RIGHT data.
mk
Vortex generators on wings allow for the creation of small turbulence so that the air flow over the wing stays attached and that air can still effect the trailing edge of the wing control surfaces. (AT the cost of higher drag, but its worth it for the extra control you get for it.) Normally, when a wing starts to stall, the separation creates drag and the control surfaces now dont have air moving over them. vortex generators create a turbulence that keeps the flow attached to the wing surface, even though it is now very "disturbed" yet flowing over the control surfaces.
If this was some novel idea that works, all planes would be wrapped , or made with dimples. after all, I think Boeing has a few wind tunnels to work with
2 seconds faster a lap??? com'mon! you could get a rough drag number for the car at 100mph lets say. It might be 50lbs of force to drive the drag alone. If you removed ALL of the drag entirely, that would be like 50hp at that speed, (and any slower less, any faster more) Then, would 50hp give you 2 seconds a lap? probably not, and the reduction of drag, if any , is no where near eliminating all the drag.
Now, all they need to do is get a drag coeficient value at a wind tunnel and be done with the experiment. all these things are very easy to calculate once you have the RIGHT data.
mk
Aircraft manufacturers know all about the effect and use vortex generators, winglets etc. to achieve the same result.
Joe, I suspect that the kind of wind tunnel you'd need to produce valid results is beyond the reach of these guys. Ideally an F1 or NASCAR style set up would be needed. Also much bucks to rent it and the staff to instrument and run the test.
I also agree that the track test is a little questionable in terms of consistent results. Without going to a full wind-tunnel, a simple coast-down test would help determine drag reduction but the effects would be greatly reduced as the vehicle slows since drag is a 3rd power exponent.
I think the idea is neat and at worst it will prevent stone chips
Joe, I suspect that the kind of wind tunnel you'd need to produce valid results is beyond the reach of these guys. Ideally an F1 or NASCAR style set up would be needed. Also much bucks to rent it and the staff to instrument and run the test.
I also agree that the track test is a little questionable in terms of consistent results. Without going to a full wind-tunnel, a simple coast-down test would help determine drag reduction but the effects would be greatly reduced as the vehicle slows since drag is a 3rd power exponent.
I think the idea is neat and at worst it will prevent stone chips
04-21-2009, 04:42 PM
#12
Rennlist Member
I would feel much more comfortable about the results, (or question it less) if someone that was driving the cup car was a known quantity. 2 seconds a lap is a huge margin of difference. This lap time difference could be caused normally by 50-100hp increase equivilant effect or going from real slicks from DOT tires. I just dont see this drag reduction being anywhere near that kind of weighted effect.
mk
mk
04-21-2009, 04:42 PM
#13
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Mark, at speed isn't the majority of the power used to overcome aerodynamic drag? You mentioned 50 HP, but I think you are being very conservative. Other than drag what prevents my car from going faster. I have seen estimates of how much HP it takes to make the same car go from 190 to 200 MPH and the numbers are pretty large.
04-21-2009, 05:05 PM
#15
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Two different things here, right? power to go a faster speed, and power consumed by the drag during acceleration. The power required to achieve the faster speed, goes up with the cube of speed. (double the speed, 8x the power) So, if you have a 200mph car that gets max HP right at 200mph, the power to drive the drag will be 1/8 at 100mph. Say you have a 500rwhp car and you can go 200mph. At 100mph, the power required to drive the drag will onlyh be 62.5HP. Now thats aero and friction drag. at 150mph, that number goes up to ( 1.5^3 x 62.5 = 210hp). But, you have to calculate how long you are at 150mph to get a value of how much the HP savings will be.
Rough estimation:
At Road america, there are 3 straigths getting to 150mph for 400hp cars.
the straights are 20seconds long in total. the last 15 seconds might be from100 to 150mph. over 45 seconds a lap of WOT on these straights, what can the savings of HP buy you.
Lets say we could reduce drag by 10% (which is a big number) .4 Cd to .36. (basically like getting all your aero downforce for free as most street cars are .36 drag coefficient). what would it save? Take that number and apply it at all the speed ranges. its going to be a small value. PLUS, this dimple wrap in no way can lower Cd by 10%.
so, even if you took the total effects of removing the 10% of the 210HP required to drive the car at 150mph, it would be a a 21hp effect on the the car. I dont think 21hp gives 2 seconds a lap, and more than half that is a gift, as you dont spend much time at 150mph on most tracks. take an average. 210+62 /2 = 136hp x 10%, thats only 14hp. not going to give you 2 seconds a lap. trust me. Ive played with NOS 50hp shots on road courses. It was like 1 second tops.
mk
Rough estimation:
At Road america, there are 3 straigths getting to 150mph for 400hp cars.
the straights are 20seconds long in total. the last 15 seconds might be from100 to 150mph. over 45 seconds a lap of WOT on these straights, what can the savings of HP buy you.
Lets say we could reduce drag by 10% (which is a big number) .4 Cd to .36. (basically like getting all your aero downforce for free as most street cars are .36 drag coefficient). what would it save? Take that number and apply it at all the speed ranges. its going to be a small value. PLUS, this dimple wrap in no way can lower Cd by 10%.
so, even if you took the total effects of removing the 10% of the 210HP required to drive the car at 150mph, it would be a a 21hp effect on the the car. I dont think 21hp gives 2 seconds a lap, and more than half that is a gift, as you dont spend much time at 150mph on most tracks. take an average. 210+62 /2 = 136hp x 10%, thats only 14hp. not going to give you 2 seconds a lap. trust me. Ive played with NOS 50hp shots on road courses. It was like 1 second tops.
mk
Mark, at speed isn't the majority of the power used to overcome aerodynamic drag? You mentioned 50 HP, but I think you are being very conservative. Other than drag what prevents my car from going faster. I have seen estimates of how much HP it takes to make the same car go from 190 to 200 MPH and the numbers are pretty large.