SwayBar

I've read where Carrol Shelby (..I think it was him, or was it Carrol Smith?) first starting using wings and did the very thing you mentioned for the same reason.

mark kibort

we are saying the same thing here. my point was because mark has the attachment points in toward the rear axle, he is not taking advantage of the attahment point leverage. he now has to extend way beyond the rear of the car backward to great the same force dowward, as a wing flush with the rear of the car that is angled back from the rear hatch mounting.

so, say mark attached his wing right at the axle points, and angled back his uprights all the way to where my wing was sitting.........ohhhhh i see. Your right!!!!

I think im wrong on this one. so, as far as leverage goes, where ever the wing ends up (relative to the distance to the plane of the rear wheels), the same down force will be applied. my wing at 100lbs of downforce right above the rear hatch will be 2.5 feet from the axles so, 250lbs of downforce to the axle. Mark attaching to the shock tower, running uprights back 2.5 feet would do the same thing. i think i get it now. is that the idea?

so, back to my original point , you need less of a structure holding the wing in place if the uprights are shorter and less tall. this is why mine being only about 14" tall and at a very slight angle, doest require as much strength for drag forces acting on the wing and uprights. again, if the drag is 5-50lbs(which would be 50 to 500lbs of wing downforce) all you need to do is see how that flexes the uprights as they pull up in front and push down in the rear. the "strength" of the materials shape and composition will determine this. right now, pulling on the back wing, the most flexing i see is actually the steel hatch, and it is barely moving at all. (a tiny flex in the upright brackets) If you look at the wings that need the cross members, they are made out of very thin aluminum and maybe a lesser grade. mine has very little side to side flex. actuallly the same amount as the GT3 cup car it came off of. (mine is half as high so i dont need the width of the wing uprights. actually, i have half the area of the originals that came off the GT3 cup car. (because im at 1/2 the hight)

Mk

mark kibort

hmmm, so you get those "spinners" and mount the wing to them? KIDDING!

yes, they would mount the wings to the unsprug parts of the suspension, just before the wheel attachement. you got the downforce and no spring compression. Now, since mark was cutting away, he should have dug a little deeper and attached his wing to the rear hub! actually, now you get in all sorts of other issues, due to the wing following the rapid up and down movement of the wheel. i think compression of the spring is and can be a good thing. (they are talking about HUGE downforce that compresses the springs to the bumpstops and causes bad bumpsteer issues) in our case, the compression stiffens the spring at the high speed range, where you would want some stiffer compliance anyway. im sure there is a lot of trade offs here!

MK

Dennis K

Yeah it'd be really cool to see the wing struts go through the frame all the way to the suspension. You'd probably have to hide it somewhat to get around rules against "moveable aerodynamic devices". You could probably get away w/ it for local club racing though . . . until you started winning.

I think Jim Hall was the first guy to attach a wing to the suspension. After that they sprouted up on the Lotus 49's in F1. Found a couple pics of the Chaparral 2E design:

Jim bailey - 928 International

Historical note...."In practice Mercedes also dabbled with a so-called "air brake", a moveable spoiler on top on the roof that could be put in use by the driver to assist the drum brakes. But it was not until 1955 that the contraption, in a somewhat adapted form, actually raced. ".... drivers behind the Mercedes complained that when the barndoor poped up they could not see past the car ! Justification for the ban on driver movable body parts.

fabric

I thought that same, but couldn't find the pictures to verify it. Thanks for posting the pics Dennis, good find! One of the rags, I think R&T, had an article on the Chaparrals a while ago, they had a lot of problems keeping that wing on.

Does this count as a moveable aero device? While the wing technically "moves" it isn't adjustable, which is the intent of the rule, I'd think. The angle of attack on the wing is still fixed. It would still be pretty hard to work something like that on any production car, since you have to mount to the outboard side of the suspension.

GT Jackson

Rookie question. When you say you are flying the wing, does that imply you have an upside down airfoil for downforce?

Gordon

mark kibort

all of the wings are upside down. you certainly dont want airplane lift on the rear or front of the car. cars dont fly welll, once they get airborne.

Most of the discussion now, is about an adjustable air foil that could change the angle of attack dynamically. flat on the straights and angled down for upcoming turns.

the point of attaching the wings to the suspension hubs, was to not applie the wings to the "sprung" chassis, as the downforce could compress the springs and change the handling. I dont think this is that much of an issue, especially when you think about the need for more spring as you go faster. it could be an asset in some cases. plus on a bumpy fast corse, the wing is not going to move up and down with the wheels over the bumps, and then taking the effectiveness away from the shocks. You in effect would then have an "air shock" on the wing if attached to the wheel hubs directly. now that could change the damping characteristics of the shocks at high speeds.

mk

GT Jackson

Just checkin'. I wasn't sure whether or not you guys were just sticking a board in the wind or dealing with airfoils This being the case, there being much discussion about stalling the wing as well as drag, what thought is given to the design of the airfoil its self, and how changing the shape of the airfoil can alter the lift/drag coefficient. So rather than alter the angle of attack, change the lift with a fowler flap that could be employed or deployed or some other way to increase lift (ooops, I mean downforce) as speed drops. Did I read about mechanical deployments being prohibited?

worf928

I cannot speak for Kibort, but when I write 'flying the wing' I refer to the performance envelope of the wing in which the lift is greater (far greater) than the drag. When the wing is operating in the region wherein drag is equal-to or greater-than the wing I write 'dragging the wing.'

Moveable (as in dynamic, not adjustable) aerodynamic aids are prohibited. Also, as far as I know, the folks in this forum that have wings do not have the luxury of picking their airfoil - except in that they may be able to choose between a handful of profiles. Given that, the challenge is to determine what range of relative attack angles are useful. I wrote 'relative' since the air coming off the roof and hatch of the 928 may not be parallel to the ground depending upon how high the wing is mounted.

mark kibort

No, this sport has evolved enough to take advantage of real air foils and gurney flaps. most of the air foils here make their max lift at near 18 degrees and the angle of attack which has to be made up of not only its position from level, but the air flow diverted from the roof line. drag at a maximum for a NACA Clark Y air foil is about 8:1. not bad. (asymetrical flat bottomed air foil) i think most of the top racers try and get near this depending on the balance of the car, aerodynamically. you certainly dont want huge down force in the rear going through a 100mph kink if you dont have the balance up front.

many of the air foils used on cars are flat bottomed, and many incorportate a slight banana shape to them.. on F1, they are very curved, so that they can be even more efficient at high effective angle of attacks.

end plates are used to increase efficiency of the wings and the gurney flaps are used to effectively change the angle of attack, without much of the drag associated with doing so.

as i mentioned i had a 10 degree, plus 9 more degrees of angle on my tilted GTS wing. (not really an air foil) it produced 80lbs of downforce at 120mph. now, i have a real air foil at 7 degrees (plus the 9 degrees of deflection off the roof) and have measured 130lbs of downforce at only 100mph . 50 more lbs of down force, 3 degrees less angle of attack, 20mph less speed, and a real air foil to reduce drag. L/D ratios of near 10:1. so, that 130lbs of drag is only costing me at 100mph, 13lbs of drag, through the gear box at 100mph , less than 3ft-lbs of engine torque...... not bad!

MK

mark kibort

when lift is equal to drag, this happens on a Asymetrical air foil at about 28 to 32degrees. However, no more lift was produced after 19 degrees, but drag is continuing to increase. Main point here, you better have access to a wind tunnel or a book or you are shooting in the dark. (i count on this with my competitors) . So, "draging the wing" as you say, is pretty common and many of the folks just dont get it.

Mk

Dennis K

Basically the rules in auto racing have evolved to require the aero device to be fixed and be part of the sprung chassis. They don't allow moving flaps.

However, in the Chaparral shown in the pics above, the wing did change angle of attack. The car had an automatic transmission, so no clutch pedal. The 3rd pedal was instead connected to the wing which, when pushed, flattened the angle of attack. This was eventually banned.

EVERYBODY in every racing series tries to reduce the drag from these supposedly fixed aero devices by playing w/ the grey area of the rules. They've tried flexible wing elements to close slot gaps on multi-element wings, flexible mounts to change angle of attack, moveable rear windows to deflect air away, and that's only what has been seen THIS year. The game has been going on for 40 years.

GlenL

Yep. Check out a recently locked thread. The angle looked pretty severe. Was going to suggest doing some research, but the thread was locked when I tried to post.

I have seen ricers with the wing angled wrong, that is to give lift. Probably figured it made the car lighter.

GT Jackson

Wow! Very interesting. This piques my interest as a avaition nut and to think how the advances in airfoil management might be applied to autos. Obviously I am not alone as I am sure much attention and engineering has gone into this study by those who can afford it.

Much can be done to vary the shape of thin high speed airfoil by applying slats and flaps creating significant force even at relatively low speeds, and then can be cleaned up for minimum high speed drag.

Obviously you guys are well aware of these effects. I would find it an interesting challenge too.

Thanks.

Gordon