Wing effects on other stockish 928 racers?
07-11-2006, 05:25 PM
#1
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Wing effects on other stockish 928 racers?
JV and Stan, and others with trackable 928s with big wings,
what kind of wing angle of attacks have you run, and how did your big wings feel when you first put them on at the track. Noticable better rear tracking? more front push? better high speed cornering, with earlier ability to apply gas?
Just curious. I have to wait an entire month before my next race to check out my new GT3cup wing.
right now, ive verified that im getting near 130lbs of downforce at half the angle of attack of my "tilted" S4/GTS wing set at 10 degrees, which had close to near 80lbs at the same speed.
based on the air foil type and angle of attack, even with the flow downward from the roof line, lift to drag rations are probably in the 10:1 range. so the increased drag of the increased lift , not to mention efficiency differences, would amount to 5lbs of drag for 50lbs of increased lift (or downforce). So, i dont expect my straightline speed to be hurt too much, if any.
5lbs of drag, through 3rd gear ratio of 4.5:1, is around 1ftlb of torque at the engine flywheel. seems weird, but true!
thanks,
MK
what kind of wing angle of attacks have you run, and how did your big wings feel when you first put them on at the track. Noticable better rear tracking? more front push? better high speed cornering, with earlier ability to apply gas?
Just curious. I have to wait an entire month before my next race to check out my new GT3cup wing.
right now, ive verified that im getting near 130lbs of downforce at half the angle of attack of my "tilted" S4/GTS wing set at 10 degrees, which had close to near 80lbs at the same speed.
based on the air foil type and angle of attack, even with the flow downward from the roof line, lift to drag rations are probably in the 10:1 range. so the increased drag of the increased lift , not to mention efficiency differences, would amount to 5lbs of drag for 50lbs of increased lift (or downforce). So, i dont expect my straightline speed to be hurt too much, if any.
5lbs of drag, through 3rd gear ratio of 4.5:1, is around 1ftlb of torque at the engine flywheel. seems weird, but true!
thanks,
MK
Last edited by mark kibort; 07-15-2009 at 06:19 PM.
07-11-2006, 05:38 PM
#2
Banned
hmmmm, mark, not to hijack, but I am looking at your car in the picture... do you actually have any of those E chargers installed? if so, could you send me your impressions in a PM just for ****s and giggles?
07-11-2006, 07:29 PM
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I have to thank Anderson for that tip at the track. after all, he kind of guided me to the light!
yeah, paying $ 0 - 50 for a set of used Toyos is one thing, but a Carbonfiber cup car wing in the can is another!
Thanks Mark! hope i works!
Mk
yeah, paying $ 0 - 50 for a set of used Toyos is one thing, but a Carbonfiber cup car wing in the can is another!
Thanks Mark! hope i works!
Mk
Originally Posted by animal8526
yeah, ditto on the wing. real aggressive
07-11-2006, 07:47 PM
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I first tested it out with all the intake variations we tried several years ago. the eRAM didnt really do anything do to the mass flow requirements of a 320rwhp engine being outside its capability. on 240rwhp, it helped a bit, near 10hp.
We tried the eRAM on my car with it attached directly to the rear of the air box. (with the 2 front fed tubes still opend as normal,so we are obviously not pressurizing now) what happened is that we gained about 5hp, and it was pretty consistant from run to run, and then with it removed, the 5hp went away and the curve was a slightly different shape. I guess, in this application, the eRAM must make the flow more efficient to the MAF. we did tests on the hyway too, and at 100mph, with and without the eRAM the pressure in the air box changed slightly as well, even though it was heavily vented! aero is some complicated stuff. Im sure there are a dozen factors going on here!
now, back to the wing!
Mk
We tried the eRAM on my car with it attached directly to the rear of the air box. (with the 2 front fed tubes still opend as normal,so we are obviously not pressurizing now) what happened is that we gained about 5hp, and it was pretty consistant from run to run, and then with it removed, the 5hp went away and the curve was a slightly different shape. I guess, in this application, the eRAM must make the flow more efficient to the MAF. we did tests on the hyway too, and at 100mph, with and without the eRAM the pressure in the air box changed slightly as well, even though it was heavily vented! aero is some complicated stuff. Im sure there are a dozen factors going on here!
now, back to the wing!
Mk
Originally Posted by animal8526
hmmmm, mark, not to hijack, but I am looking at your car in the picture... do you actually have any of those E chargers installed? if so, could you send me your impressions in a PM just for ****s and giggles?
Last edited by mark kibort; 07-15-2009 at 06:19 PM.
07-12-2006, 02:16 PM
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Hi Mark,
JV says he didn't need no stinkin' wing with his mouse motor. I know he is considering it now with the stroker upgrade.
David Lloyd and I have similar wings and similar installations. We both also run splitters. Our wings are adjustable from 0 to 10 degrees in 2.5 degree increments as I recall. At higher speed tracks, like Watkins Glen, I would leave the wing at 0 degrees, at lower speed tracks, like Lime Rock, I have set it at the 2.5 and 5 degree, and have found the second setting to be too much. I will be noticably slower on the straights and not any faster in the corners. I was suprised at the difference the wing made on relatively slow corners too, like the left hander at Lime Rock.
Much, if not all, of this, is based on memory. Keep in mind that our use of splitters will make a big difference. I think David ran without his splitter once with the wing and had big handling issues.
Of course the profile of the wing can make a big difference. David had provided our wing profile to David Chamberland for review, and the response from David Lloyd (in an email I saved) was:
" I spoke with Dave Chamberland last night, having sent him a profile of the wing for his cohorts at MIT to examine. The consensus is, based on the smoke path depicted in Project 928, that our wing works best at between minus 5 (not that we can set it there) and plus 5 degrees from horizontal. Anything above 10 degrees and we will approach "stall" at top speed. However, using 10 in the rain should be fine, but no higher."
JV says he didn't need no stinkin' wing with his mouse motor. I know he is considering it now with the stroker upgrade.
David Lloyd and I have similar wings and similar installations. We both also run splitters. Our wings are adjustable from 0 to 10 degrees in 2.5 degree increments as I recall. At higher speed tracks, like Watkins Glen, I would leave the wing at 0 degrees, at lower speed tracks, like Lime Rock, I have set it at the 2.5 and 5 degree, and have found the second setting to be too much. I will be noticably slower on the straights and not any faster in the corners. I was suprised at the difference the wing made on relatively slow corners too, like the left hander at Lime Rock.
Much, if not all, of this, is based on memory. Keep in mind that our use of splitters will make a big difference. I think David ran without his splitter once with the wing and had big handling issues.
Of course the profile of the wing can make a big difference. David had provided our wing profile to David Chamberland for review, and the response from David Lloyd (in an email I saved) was:
" I spoke with Dave Chamberland last night, having sent him a profile of the wing for his cohorts at MIT to examine. The consensus is, based on the smoke path depicted in Project 928, that our wing works best at between minus 5 (not that we can set it there) and plus 5 degrees from horizontal. Anything above 10 degrees and we will approach "stall" at top speed. However, using 10 in the rain should be fine, but no higher."
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07-12-2006, 02:41 PM
#8
Race Car
It will be interesting to see what happens to your lap times as that is the bottom line.
07-12-2006, 10:17 PM
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based on our wings, and most are pretty close to the same in a general sense, they will be effective up to 15 degrees, off the relative wind, but as your MIT folks stated, that was probably was at 5degrees from horizontal due to the flow off the roof line aiming down by about 10 degrees.
they mentioned at top speed stall, and that would be hard to imagine due to most air foils getting near stall and producing a 1:1 lift to drag ratio. that would be huge lift and huge drag. where that point will be, is a question, but based on almost all race car wings runnin anywhere from 0 to 15 degrees, i think it would be fine to operate in this range for the speeds we run at.
as a side note, there is almost no downforce at the slower speeds, so a wing wont really do anything in the slow corners, however a high speed approach may be helped due to keeping the rear end down and helping with rear brakes.
you mentioned not being able to set the wing at -5 degrees? all you need is a little two holed piece of aluminum to do this. at -5 degrees, the wing effectively would be more flat and probably close to neutral, based on the smoke tracks you mention. however, even a - 5 degrees angle of attack, will probably have greater than 0 angle of attack based on relative wind. even if it is flat, an asymetrical wing will make lift at 0 as well. (or downforce i should say)
hard to imagine any real difference in straight line speed. keep in mind, most air foils have a 10:1 lift to drag number. (it can range from 8:1 to 15:1 depending on the air foil and the angle of attack) so, even if you could produce a massive 200lbs of downforce, the net force against your acceleration would only be in the 20lb range. and through a gear box, say 3rd of near 4.5:1, it would be less than effectively, 5ftlbs of torque at the engine.
(in 2nd a lot less, and in 4th 30% more) But still not really as much as most think. you wont really know about straightline speed unless you have an accurate way of testing it. I know the speed GT corvette guys noticed less than 1mph down the main straightaway reduction for a high wing setting or their mandated 40% restrictor (loosing 15hp only!) during testing (mcClure's famous vet)
since i have so many laps at sears and laguna and my last 4 to 5 races have produced times within a few tenths of each other, it will be interesting to see the difference. but i already know im getting 50lbs more downforce than my tilted GTS wing ( and at the charts 10degree angle of attack, a 12:1 lift /drag ratio.) so those 50lbs is going to only cost me less than 4lbs of drag, through a gear box, less than 1ft-lb on the flyweel.
I have done the 60-100mph tests and seen no difference in time and you all know i do this several times every single weekend on the same streatch of road.
Thanks for the info/impressions on the wing on your racers of the east!
MK
they mentioned at top speed stall, and that would be hard to imagine due to most air foils getting near stall and producing a 1:1 lift to drag ratio. that would be huge lift and huge drag. where that point will be, is a question, but based on almost all race car wings runnin anywhere from 0 to 15 degrees, i think it would be fine to operate in this range for the speeds we run at.
as a side note, there is almost no downforce at the slower speeds, so a wing wont really do anything in the slow corners, however a high speed approach may be helped due to keeping the rear end down and helping with rear brakes.
you mentioned not being able to set the wing at -5 degrees? all you need is a little two holed piece of aluminum to do this. at -5 degrees, the wing effectively would be more flat and probably close to neutral, based on the smoke tracks you mention. however, even a - 5 degrees angle of attack, will probably have greater than 0 angle of attack based on relative wind. even if it is flat, an asymetrical wing will make lift at 0 as well. (or downforce i should say)
hard to imagine any real difference in straight line speed. keep in mind, most air foils have a 10:1 lift to drag number. (it can range from 8:1 to 15:1 depending on the air foil and the angle of attack) so, even if you could produce a massive 200lbs of downforce, the net force against your acceleration would only be in the 20lb range. and through a gear box, say 3rd of near 4.5:1, it would be less than effectively, 5ftlbs of torque at the engine.
(in 2nd a lot less, and in 4th 30% more) But still not really as much as most think. you wont really know about straightline speed unless you have an accurate way of testing it. I know the speed GT corvette guys noticed less than 1mph down the main straightaway reduction for a high wing setting or their mandated 40% restrictor (loosing 15hp only!) during testing (mcClure's famous vet)
since i have so many laps at sears and laguna and my last 4 to 5 races have produced times within a few tenths of each other, it will be interesting to see the difference. but i already know im getting 50lbs more downforce than my tilted GTS wing ( and at the charts 10degree angle of attack, a 12:1 lift /drag ratio.) so those 50lbs is going to only cost me less than 4lbs of drag, through a gear box, less than 1ft-lb on the flyweel.
I have done the 60-100mph tests and seen no difference in time and you all know i do this several times every single weekend on the same streatch of road.
Thanks for the info/impressions on the wing on your racers of the east!
MK
Originally Posted by Stan.Shaw@Excell.Net
Hi Mark,
JV says he didn't need no stinkin' wing with his mouse motor. I know he is considering it now with the stroker upgrade.
David Lloyd and I have similar wings and similar installations. We both also run splitters. Our wings are adjustable from 0 to 10 degrees in 2.5 degree increments as I recall. At higher speed tracks, like Watkins Glen, I would leave the wing at 0 degrees, at lower speed tracks, like Lime Rock, I have set it at the 2.5 and 5 degree, and have found the second setting to be too much. I will be noticably slower on the straights and not any faster in the corners. I was suprised at the difference the wing made on relatively slow corners too, like the left hander at Lime Rock.
Much, if not all, of this, is based on memory. Keep in mind that our use of splitters will make a big difference. I think David ran without his splitter once with the wing and had big handling issues.
Of course the profile of the wing can make a big difference. David had provided our wing profile to David Chamberland for review, and the response from David Lloyd (in an email I saved) was:
" I spoke with Dave Chamberland last night, having sent him a profile of the wing for his cohorts at MIT to examine. The consensus is, based on the smoke path depicted in Project 928, that our wing works best at between minus 5 (not that we can set it there) and plus 5 degrees from horizontal. Anything above 10 degrees and we will approach "stall" at top speed. However, using 10 in the rain should be fine, but no higher."
JV says he didn't need no stinkin' wing with his mouse motor. I know he is considering it now with the stroker upgrade.
David Lloyd and I have similar wings and similar installations. We both also run splitters. Our wings are adjustable from 0 to 10 degrees in 2.5 degree increments as I recall. At higher speed tracks, like Watkins Glen, I would leave the wing at 0 degrees, at lower speed tracks, like Lime Rock, I have set it at the 2.5 and 5 degree, and have found the second setting to be too much. I will be noticably slower on the straights and not any faster in the corners. I was suprised at the difference the wing made on relatively slow corners too, like the left hander at Lime Rock.
Much, if not all, of this, is based on memory. Keep in mind that our use of splitters will make a big difference. I think David ran without his splitter once with the wing and had big handling issues.
Of course the profile of the wing can make a big difference. David had provided our wing profile to David Chamberland for review, and the response from David Lloyd (in an email I saved) was:
" I spoke with Dave Chamberland last night, having sent him a profile of the wing for his cohorts at MIT to examine. The consensus is, based on the smoke path depicted in Project 928, that our wing works best at between minus 5 (not that we can set it there) and plus 5 degrees from horizontal. Anything above 10 degrees and we will approach "stall" at top speed. However, using 10 in the rain should be fine, but no higher."
07-12-2006, 11:10 PM
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Originally Posted by Stan.Shaw@Excell.Net
Of course the profile of the wing can make a big difference. David had provided our wing profile to David Chamberland for review, and the response from David Lloyd (in an email I saved) was:
" I spoke with Dave Chamberland last night, having sent him a profile of the wing for his cohorts at MIT to examine. The consensus is, based on the smoke path depicted in Project 928, that our wing works best at between minus 5 (not that we can set it there) and plus 5 degrees from horizontal. Anything above 10 degrees and we will approach "stall" at top speed. However, using 10 in the rain should be fine, but no higher."
" I spoke with Dave Chamberland last night, having sent him a profile of the wing for his cohorts at MIT to examine. The consensus is, based on the smoke path depicted in Project 928, that our wing works best at between minus 5 (not that we can set it there) and plus 5 degrees from horizontal. Anything above 10 degrees and we will approach "stall" at top speed. However, using 10 in the rain should be fine, but no higher."
Also, note Stan's comment about the splitter: With a few hundred pounds of downforce on the rear you'll be upsetting the front end in higher-speed corners unless you do something aero-wise at the front too.
The best solution would be to use ground-effect with a full-body undertray and rear diffuser. But, that ain't something I can opine on with the measly software available to me. Now, if you get me some wind tunnel time...
07-12-2006, 11:14 PM
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Mark, one other thing: your wing looks like it is mounted 6 or so inches lower than the East Coasters. Take a look at Project 928 and see where you think the smoke lines will be hitting your wing. I'll bet it is closer to -10 degrees than -5. But, all math aside - what counts in the end is lap times and consistency in handling.
07-13-2006, 03:43 AM
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I did this, kind of by design. since there is a flow around the body that is part of a drag issue in itself, i wanted to use this deflected air that heads down to the stock wings, but also use a majority of the air flow near the rear of the car to create downforce. the cup cars have the wing about 6" below the roof line for this reason as well, as i have been told.
I agree,its probably like 10degree deflection like you say, so my effective angle of attack is near 16 degrees and is probably the reason for the 130lbs of downforce vs the stock wing at 10 degrees, (effectively 20 degrees) that only produced 80lbs of downforce in the rear.
The car is handling pretty well right now. if you think about it, im running 3 secodns faster than Anderson at the first time he visited Sears Point in 2000 with him having 100more hp. (1:47.9 vs 1:51.2) also that is a time that is faster than top pro driver (at the time) Peter Kitchack in his famed 911RSR, and near Phil mcclure and Scotty white in their speedvision vets. so, im hoping i dont change thing so much that i get away from a 928 that is handling so well right now. However, i do feel on some of the long , fast , turns, that i could get on the power earlier if i had some way to stick the rear even better. (maybe i just need a new set of tires!)
anyway, we willl soon see the effects of the new wing. certainly, i should feel some difference with the measured 50lbs of additional downforce vs the stock tillted and raised 3" stock GTS wing.
where can i get a copy of that smoke path of the "Project 928" issue?
can you post it?
Thanks for the comments. certainly many factors here.
MK
I agree,its probably like 10degree deflection like you say, so my effective angle of attack is near 16 degrees and is probably the reason for the 130lbs of downforce vs the stock wing at 10 degrees, (effectively 20 degrees) that only produced 80lbs of downforce in the rear.
The car is handling pretty well right now. if you think about it, im running 3 secodns faster than Anderson at the first time he visited Sears Point in 2000 with him having 100more hp. (1:47.9 vs 1:51.2) also that is a time that is faster than top pro driver (at the time) Peter Kitchack in his famed 911RSR, and near Phil mcclure and Scotty white in their speedvision vets. so, im hoping i dont change thing so much that i get away from a 928 that is handling so well right now. However, i do feel on some of the long , fast , turns, that i could get on the power earlier if i had some way to stick the rear even better. (maybe i just need a new set of tires!)
anyway, we willl soon see the effects of the new wing. certainly, i should feel some difference with the measured 50lbs of additional downforce vs the stock tillted and raised 3" stock GTS wing.
where can i get a copy of that smoke path of the "Project 928" issue?
can you post it?
Thanks for the comments. certainly many factors here.
MK
Originally Posted by worf928
Mark, one other thing: your wing looks like it is mounted 6 or so inches lower than the East Coasters. Take a look at Project 928 and see where you think the smoke lines will be hitting your wing. I'll bet it is closer to -10 degrees than -5. But, all math aside - what counts in the end is lap times and consistency in handling.
07-13-2006, 03:57 AM
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Got it, and i understand. but generally, the downforce curves of common air foils dont really have a sweet spot. the curve heads south ( drag/lift) in almost a linear fasion as you get more down force. so, so as you get near stall, it spikes, but it its a pretty clear point at which this happens. I dont think too many racers are dragging around parachutes, but if you look at some of the pro teams with lots of HP, they may! high angle of attacks, plus gurney flaps, definitely gets near that range i would imagine. However, playing in the 5-20 degree wing settings are probalby not there.
I do understand to match a splitter for front downforce as well. I employ a simple cup car splitter up front as well. not huge , but effective. front feels pretty planted on high speed turns, and only is tail happy, in a good way. hopefully, the rear downforce doesnt change the front down force , which it may. its not like changing ride hight settings where you gain rear weight and make the front lighter. you increase downforce in the rear and as long as the chassis, doesnt change its attitute too much (ie movement from the weight of the downforce of 50lbs in the rear) it should be ok. the interesting thing about what im doing , is its like the weight i have in the car in the start of some races in the rear. so, i already know what this is like, however, you dont have the centrifugal force of the weight being there , just the pure downforce. so, at the end of the race, ill have the "more gas" weight in the back without having the downside effects of it.
as far as the drag down the straights, i dont see how this is much of a factor up to 120mph or so. worst case its only around 1-3ft-lbs of torque at the flywheel, right?? 50lbs of downforce, 5lbs of drag, divided by 3rd gear (4.5:1)
Plus we are talking about a more efficient wing vs my higher angle, lower downforce tilted , raised GTS wing, which is really not much of a wing at all. the efficiency may make the drag of the two equal and it will mean 50lbs of downforce is for free.
MK
I do understand to match a splitter for front downforce as well. I employ a simple cup car splitter up front as well. not huge , but effective. front feels pretty planted on high speed turns, and only is tail happy, in a good way. hopefully, the rear downforce doesnt change the front down force , which it may. its not like changing ride hight settings where you gain rear weight and make the front lighter. you increase downforce in the rear and as long as the chassis, doesnt change its attitute too much (ie movement from the weight of the downforce of 50lbs in the rear) it should be ok. the interesting thing about what im doing , is its like the weight i have in the car in the start of some races in the rear. so, i already know what this is like, however, you dont have the centrifugal force of the weight being there , just the pure downforce. so, at the end of the race, ill have the "more gas" weight in the back without having the downside effects of it.
as far as the drag down the straights, i dont see how this is much of a factor up to 120mph or so. worst case its only around 1-3ft-lbs of torque at the flywheel, right?? 50lbs of downforce, 5lbs of drag, divided by 3rd gear (4.5:1)
Plus we are talking about a more efficient wing vs my higher angle, lower downforce tilted , raised GTS wing, which is really not much of a wing at all. the efficiency may make the drag of the two equal and it will mean 50lbs of downforce is for free.
MK
Originally Posted by worf928
Just to clarify: The recommendation to DL and Stan was aimed at maximizing downforce and minimizing drag - i.e. keeping the wing in its efficient operating region with respect to the lift/drag ratio. You could of course operate near, at, or beyond the stall region of the wing and get significant downforce but you'd be dragging the wing through the air rather than 'flying' it. With the Mouse Motors that wasn't where Stan and Dave wanted to run.
Also, note Stan's comment about the splitter: With a few hundred pounds of downforce on the rear you'll be upsetting the front end in higher-speed corners unless you do something aero-wise at the front too.
The best solution would be to use ground-effect with a full-body undertray and rear diffuser. But, that ain't something I can opine on with the measly software available to me. Now, if you get me some wind tunnel time...
Also, note Stan's comment about the splitter: With a few hundred pounds of downforce on the rear you'll be upsetting the front end in higher-speed corners unless you do something aero-wise at the front too.
The best solution would be to use ground-effect with a full-body undertray and rear diffuser. But, that ain't something I can opine on with the measly software available to me. Now, if you get me some wind tunnel time...
07-13-2006, 04:18 AM
#14
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Hey, last time i noticed, it didnt take 500hp to go around the carocell (sears or road america) at 100mph vs 105mph I think its even more critical for a car to handle well if it doesnt have the power. remember the Speed touring guys i run with at laguna when they practice for their SpeedGT touring race?? they run 2:27s at Road America. (top 10 under 2:30) they weigh close to what we weigh and have only about 275 to 300rwhp (depnending on who you talk to )
I think MUCH of this is their suspension, tuning and driving , in areas of the kink and carrocel at RA.
If a wing can produce 100lbs more down force , only cost you 10 ft-lbs of torque, 2 ftlbs reflected to the flywheel, and not really take away from what you have up front, its not a wonder every single race car except JV and me have wings! I was in denial for a long time about this, thinking that it was part of the reason my car was running so well against these wing'ed beasts. turns out, ive dung a little deeper into the wing area, having a passion for aero anyway. Now the truth will be told.
anyone see a issue with my drag relationships? it seems like something for nothing, but i certainly dont see any obvious reasons why drag, straightline speed is really a problem due to gearing and the speeds were are talking about.
Of course if we were talking about 150mph Road america, and you got 50 more lbs of downforce at 100mph, it would be 112 more lbs of downforce at 150mph and 72lbs at 120mph (so, 11 and 7lbs of drag) and that could cost you between 2.5- 3.5ft-lbs of torque at the engine from after the shift from 3rd gear into 4th at near 120mph to 150mph. is 3 ft-lbs lost at the flywheel, really a consideration?? am i missing something here?
Mk
I think MUCH of this is their suspension, tuning and driving , in areas of the kink and carrocel at RA.
If a wing can produce 100lbs more down force , only cost you 10 ft-lbs of torque, 2 ftlbs reflected to the flywheel, and not really take away from what you have up front, its not a wonder every single race car except JV and me have wings! I was in denial for a long time about this, thinking that it was part of the reason my car was running so well against these wing'ed beasts. turns out, ive dung a little deeper into the wing area, having a passion for aero anyway. Now the truth will be told.
anyone see a issue with my drag relationships? it seems like something for nothing, but i certainly dont see any obvious reasons why drag, straightline speed is really a problem due to gearing and the speeds were are talking about.
Of course if we were talking about 150mph Road america, and you got 50 more lbs of downforce at 100mph, it would be 112 more lbs of downforce at 150mph and 72lbs at 120mph (so, 11 and 7lbs of drag) and that could cost you between 2.5- 3.5ft-lbs of torque at the engine from after the shift from 3rd gear into 4th at near 120mph to 150mph. is 3 ft-lbs lost at the flywheel, really a consideration?? am i missing something here?
Mk
Originally Posted by Stan.Shaw@Excell.Net
Hi Mark,
JV says he didn't need no stinkin' wing with his mouse motor. I know he is considering it now with the stroker upgrade.
."
JV says he didn't need no stinkin' wing with his mouse motor. I know he is considering it now with the stroker upgrade.
."
07-17-2006, 12:38 PM
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I took a look at my best guess at the smoke path angles. (based on that Zip file someone posted a while ago) looks like its around 9 degrees off the roof line)
so, yes, the effective angle of attack of the wings will be whatever they are set at , plus the 9 degrees. i have mine set at 7.5 degrees now, and measured the 130lbs of donwforce at 100mph. now i know this is because there is a 9 degree adder here!. so, im near 17 degrees total. However, my tilted wing was set at 10 degrees and thats near 19 total. (we are getting near stall here)
It got only 80lbs of downforce at 120mph. (certainly was not as efficient as a real air foil) We dont know what stall really is, but Ive see race cars back from wind tunnel testing that have their wings tilted with angle of attacks of near 10-15 degrees. (vets, vipers, porsches, caddies, etc)
by the way, the stall of the wing is independent of the "top speed". stall is for a given airfoil will be at an angle of attack where the lift coefficient starts to head down for increased angle of attack, and the drag coeffiient continues to increase. You get a lot more down force for lift than you get for drag. even at high angles of attack, it is at least in the 4:1 range. at moderate angles of attack, near 10:1. not bad! as i said before, 130lbs of downforce at 100mph for less than 13lbs of drag............ through the gear box, etc, pretty insignificant.
FYI
By the way, do you have the smoke paths of the air flow going around the 928? It would be interesting to take a look at them!
MK
so, yes, the effective angle of attack of the wings will be whatever they are set at , plus the 9 degrees. i have mine set at 7.5 degrees now, and measured the 130lbs of donwforce at 100mph. now i know this is because there is a 9 degree adder here!. so, im near 17 degrees total. However, my tilted wing was set at 10 degrees and thats near 19 total. (we are getting near stall here)
It got only 80lbs of downforce at 120mph. (certainly was not as efficient as a real air foil) We dont know what stall really is, but Ive see race cars back from wind tunnel testing that have their wings tilted with angle of attacks of near 10-15 degrees. (vets, vipers, porsches, caddies, etc)
by the way, the stall of the wing is independent of the "top speed". stall is for a given airfoil will be at an angle of attack where the lift coefficient starts to head down for increased angle of attack, and the drag coeffiient continues to increase. You get a lot more down force for lift than you get for drag. even at high angles of attack, it is at least in the 4:1 range. at moderate angles of attack, near 10:1. not bad! as i said before, 130lbs of downforce at 100mph for less than 13lbs of drag............ through the gear box, etc, pretty insignificant.
FYI
By the way, do you have the smoke paths of the air flow going around the 928? It would be interesting to take a look at them!
MK
Originally Posted by Stan.Shaw@Excell.Net
Hi Mark,
JV says he didn't need no stinkin' wing with his mouse motor. I know he is considering it now with the stroker upgrade.
David Lloyd and I have similar wings and similar installations. We both also run splitters. Our wings are adjustable from 0 to 10 degrees in 2.5 degree increments as I recall. At higher speed tracks, like Watkins Glen, I would leave the wing at 0 degrees, at lower speed tracks, like Lime Rock, I have set it at the 2.5 and 5 degree, and have found the second setting to be too much. I will be noticably slower on the straights and not any faster in the corners. I was suprised at the difference the wing made on relatively slow corners too, like the left hander at Lime Rock.
Much, if not all, of this, is based on memory. Keep in mind that our use of splitters will make a big difference. I think David ran without his splitter once with the wing and had big handling issues.
Of course the profile of the wing can make a big difference. David had provided our wing profile to David Chamberland for review, and the response from David Lloyd (in an email I saved) was:
" I spoke with Dave Chamberland last night, having sent him a profile of the wing for his cohorts at MIT to examine. The consensus is, based on the smoke path depicted in Project 928, that our wing works best at between minus 5 (not that we can set it there) and plus 5 degrees from horizontal. Anything above 10 degrees and we will approach "stall" at top speed. However, using 10 in the rain should be fine, but no higher."
JV says he didn't need no stinkin' wing with his mouse motor. I know he is considering it now with the stroker upgrade.
David Lloyd and I have similar wings and similar installations. We both also run splitters. Our wings are adjustable from 0 to 10 degrees in 2.5 degree increments as I recall. At higher speed tracks, like Watkins Glen, I would leave the wing at 0 degrees, at lower speed tracks, like Lime Rock, I have set it at the 2.5 and 5 degree, and have found the second setting to be too much. I will be noticably slower on the straights and not any faster in the corners. I was suprised at the difference the wing made on relatively slow corners too, like the left hander at Lime Rock.
Much, if not all, of this, is based on memory. Keep in mind that our use of splitters will make a big difference. I think David ran without his splitter once with the wing and had big handling issues.
Of course the profile of the wing can make a big difference. David had provided our wing profile to David Chamberland for review, and the response from David Lloyd (in an email I saved) was:
" I spoke with Dave Chamberland last night, having sent him a profile of the wing for his cohorts at MIT to examine. The consensus is, based on the smoke path depicted in Project 928, that our wing works best at between minus 5 (not that we can set it there) and plus 5 degrees from horizontal. Anything above 10 degrees and we will approach "stall" at top speed. However, using 10 in the rain should be fine, but no higher."
Last edited by mark kibort; 07-17-2006 at 12:56 PM.