Smart Level Angle Finder and GT Wing AoA Settings?

[Rotary-Amuse]

Does anyone local to Providence or Worcester have a smart level tool with angle finder that I can borrow for an afternoon by a chance? I can throw in a deposit so you know you'll get it back

I have a wing with 18 different height and angle adjustments and I wanted to put together a reference guide before I start tweaking the setup

I have run a few track days so far on what I thought was a conservative set up. I initially wanted to set it up with as little AoA as possible to get used to the added front and rear aero to feel out the balance, but am now thinking the angle might be on the more aggressive side in looking at what my adjustment options are

Below shows the current setting (6 holes front set to highest setting back row, 3 holes rear set to highest hole) - looks like I can raise the height and add more angle by going to the lower rear right-side hole, but the fronts about maxed out for angle, right?:


Or I can move the front setting to the left lower 3 holes, and the rear to the left-side hole and the angles can be completely different - I won't know unless I adjust and measure it out

The car feels pretty well planted, but I want to know if it could feel better - what's the point of having adjustability if you don't maximize the potential, right?

Aerodynamics is still a bit of dark magic to me, and a portion of it is the science behind it with the remainder being trial and error. The idea of maximizing set up from track to track is even farther away from me now, but I know I've gotta learn to crawl before I can walk - and then run, and then maybe have a go at some fast laps with some sticky tires and day two time trials

I just want to know which way I'm heading and to what degree I am moving when I begin to make adjustments.

Does that make sense or should I just adjust it, eyeball it, then feel it out on track?

[breakaway500]

I am by NO means an expert on aero,and that being said.. I have recently been exploring the "dark magic" side of aero as well, and purchased a single element 10" chord x71" wide wing for the back of the Atom,with a 1/2" Gurney flap. I didn't set it up with an angle gauge,but angle is angle..and by eye, I started with zero angle and moved up to about 30 degrees. I found 15 degrees aoa to be the most beneficial at >90mph for me…and anything over 25 degrees aoa seemed to go in the opposite direction (wing stalling?). Height was mostly dictated by getting the wing into "clean" air.On my car, I had to raise the wing 5" over the "stock" supplied riser height and still could go
5" more before it is not in the dirty air of the "race" Atom roll bar. According to what I have read,the lower side of the rear wing should be at least 2" higher than anything on the car that would disturb the direct wind flow. The leading edge of the wing should be at least 30" behind anything that would affect the flow of air as well.On my car,the wing is 38" behind the roll bar horizontal member,so it should be OK..but I am planning on bumping it up another 5" as soon as Ciro can build me an extension.Ciro also feels that the 10" riser extension would be the optimum location for my application.
I did back to back testing at Whiskey Hill and found with the wing at 15 degrees aoa the car did not lose any top speed and the high speed stability added was dramatic! The car was much less nervous and more like a sedan than a cheese grater with wheels. I was able to go through turns 1-2-3, 5-10mph faster ( ) with the wing than without. I didn't do any lap timing ( ) but I feel it was faster.. and have usually been correct. I was coming into turn 4 with much more steam.
I would settle on a height that is in clean air and adjust the angle till you feel it going in the opposite direction and then dial it back 10 degrees. Worked for me…good luck.

(WH has another test day on October 16th,which I am planning on attending…weather permitting.. )



The Atom makes a dandy lawn mower...

[962porsche]

I have a degree in aerodynamics but at this time I'm on my way down to Austin COTA for the IMSA event .
when I get a free minute I will reply back with more info .
if your just looking to set angles a piece of flat stock and a home depot angle finder will do it .
how ever if you have mounted the wing to the trunk lid and you can push down on the wing and it move setting a angle is kind of pointless as the faster you go the more air pressure on the wing the more it moves .

[breakaway500]

"if you have mounted the wing to the trunk lid and you can push down on the wing and it move setting a angle is kind of pointless"
Good point.
I was told the foundation (mounting) of a purposeful wing is one of the most important aspects of a balanced setup. A dual element wing properly setup can produce well over a thousand pounds of downforce...something that must be considered. This APR link has some interesting stats on single and dual element wings,downforce and drag tables at various AOA and wind speeds. Interesting reading..

[962porsche]

I will say aero is far from a black art !
their is guessing what your aero package is doing.
their is theory of what you may think your aero package is or should be doing .
then their is knowing what your aero package really is doing .
99.9% of the time people do not get passed the guessing stage .
people pick wings by how they look guessing they will be a good wing for there car .
they look at the data of the drag and down force of the wing and that is ok . but the data they give you is only of the wing . as we all know air will flow over a car much different in a wind tunnel then if you just put a wing all by it's self in a wind tunnel . the numbers you get are the wings all by them self's .
so this means if you bolt the wing on a coupe it will in no way give you the same numbers as if you bolted it into a sedan .
then their is were and how you mount it .
like I stated if you mount it to a deck lid and you can move the wing by pushing down on it you have a wing that is really no good at all .
just as if you mount it to low or to high to far forward or to far back you will or could be making the wing pretty much useless .
the only true way to get the most out of a wing to achieve the best balance between low drag and the most down force is to run it in a simulation program .
how ever for most this is not a option so it brings us right back to guessing .

as I was saying PACKAGE aero has to be looked at as a hole package and not as individual components .
lets say you change the front splitter on a car it will effect the air flow over the rest of the car so this will also change the air flow around a wing .
even simple things like wing end plates can and will change the effect on how a wing will work .
we all know Gordon when I was running 1000's of hours of sim's on his car I kept coming up with very dirty air coming off his wing end plates . I did some changes and added about 30 LBS more down force and dropped drag by .0002 % .
you may not think .0002 % is allot but in fact it is when you are talking about drag number .

aero balance
this is so important but many over look it . getting down force in the rear of a car is easy most people add way to much to the rear and then at high speeds the car is unbalanced so they then start chasing setup .
I keep wanting to get to a COMSCC event but my duties with doing IMSA event's and instructing with 3 other clubs has kept me from attending any COMSCC events and setting up Gordons car .
when you add aero all you suspension settings will change the more aero you add the more you have to change your suspension setting . your changing your car from mechanical grip to aero grip and the transition from one to the other at speed . most of the time you have to change your springs to a progressive rate spring if your getting more then 500 LBS of down force . again if you don't your chasing setups . the reason is at speed you have added down force as straight or linear rate spring will not handle both mechanical grip and aero grip very well this also leads to revalving of the dampeners .
for instance say your car scales in at 2000 LBS and you have bought your race suspension for your cars static 2000 LB weight you had your dampeners valved for that spring rate but now at say 100 MPH your aero package is adding another 600 LBS to the front and 800 to the rear at speed your car will be way to soft to handle the added down force . so ok you up your linear spring rate and now your car can handle the added down force but at low speeds the car handles like dog poop .
again it comes right back around to a package .

canards
most single canards do nothing at all on street type cars . the reason is the laminar flow over and around the nose of the car . on most all street type cars you need at the least two and 3 is best .
on a car like my diasio one is all that is needed as the nose is a wedge shape .
if you have a single canard on a street car at best you maybe getting 15 to 20 lbs of down force out of it and that's at best because of laminar flow . thier is just no air running over it .
if your also running a slitter with a single canard then you are in most cases getting less out of your splitter too .
many people will use winglets on their splitters . this in theory is good but they guess on how big it should be thinking it's like a penis bigger is better . faults on most all cases !
most every sims I have run all that is needed is a 3/4 to 1.5" tall winglet to stop the air from dumping off the ends of a splitter . if it's to tall your doing nothing more then adding allot of drag as air has to flow around it and squeeze between the bumper and the winglets . think of air as a fluid and trying to get fluid thru a funnel . the to tall winglets is just packing up more air in front of it having no easy path to flow . again this also makes a canard even less affective .
ground height of a splitter .
this is some most people get totally wrong too .
air flow passing under your car is not all that bad . if your using a rear diffuser you need the air from under your car to make the diffuser work . to much is just as bad as to little . so many people drop their splitters as low as they can go . but now all it's doing is packing up air in front of the car . what does that do ? air needs some place to go the faster your car is going the more air is packing up in front of it so now your car has to push all that air out of the way . you can look at say a NASCAR and see they run there splitters right on the ground . they are controlling the air and with the design of the bumper moving the air off to the sides of the car . this works because the nose of the cars are designed and built to do so .
on a street car your bumper and nose was not designed to do this so like a fluid your doing nothing more then pushing a wall of water or in the cars case a wall of air .
this is why you will see some cars with diffusers that have a step up in the center . this lets the air pass under the car so the car doesn't have to push the wall of air .
the step up does work with some cars but not all cars .

flat bottoms .
this is also some thing people guess at . they will make then stick out past the rockers thinking it's stopping air from either getting under the car or thinking it's stopping air from getting out from under the car .
a flat bottom should be totally flat not letting air on top of the FB or letting air from between the cars floor and the FB out . a FB should also have a slight angle to it most times about a 2 degree angle is best but this depends on the car and width to length of the under side of the car but in all cases it should be just a little higher in he rear then in the front .

diffusers .
most people again get them so wrong all they do is add tons of drag .
again guessing !
a diffuser doesn't have to roll up at the trailing edge you can just end them with a straight edge and most times it's best to do so .
most diffusers work best at a 12 to 14 degree angle and no more as once you get more of a angle then that the air will start to lift off the under side of the diffuser . this again air being like a fluid will want to make the air grad ahold of the splitter once it's past the 12 to 14 degree angle creating drag .
the vertical veins on a diffuser is very important . the spacing length to width is how it will effect how the diffuser works . a diffuser needs to cerate vortexes to gain down force .to many vertical veins and the vortexes are to small and will just add drag to large and it will not create the vortexes need to add down force .
the spacing length and width are determined from the length and width of the diffuser it's self .

[Rotary-Amuse]

Thank you both very much for your insightful feedback Mark and David

I am beginning to see that if my car was a project on aerodynamics, it would have red ink all over it!

It is absolutely a backwards approach to build first then analyze after, but unfortunately that's where I am at

I will caveat my breakdown with the fact that although my car is now only used for track days, it is still registered for the streets and driven to and from the track. I piecemealed my package together with the theory that I could fine tune it to a good balance. With this being the end of my first season with aero, I am still very much at the early phases of dialing it all in. All this in addition to working on tightening the nut behind the steering wheel


1. Wing mounting points
...My wing is mounted on a lightweight hatch. I haven't pushed down on the wing or wing brackets to see if it flexes since installing it, but will add it to my to do list. Unfortunately I believe it is going to flex. Would adding flush mounted Aerocatch hood pins help assuming they solidify hatch movement or will chassis-mounting be the only option? I've seen hatches with wing mounting points notched out on the hatch, with brackets braced and welded in the trunk area coming through for new mounting points for a solid chassis mount wing - is this what you were referring to?

I believe my wing is just about flat to my roof line (so less than 2" higher than anything that would disturb the direct wind flow), but I believe it is 30" behind the roof line. I will get these measurements when I am at the garage



2. Taillight spoiler
...Do you think the addition of the taillight spoiler is helping, doing nothing or hurting when coupled with the wing?


3. Progressive springs
...I do not have a set of progressive springs; I have an entry level twin-tube internal construction coilover set (I know I know, more red ink!). My spring set up is 670 lbs/in front and 560 lbs/in rear, and I have been setting dampening to 62% stiffness (18 clicks to the right out of 29) front and rear lately. Would a dual-flow valve set with compression and rebound flow be a better direction for me? Your points regarding mechanical grip to aero grip with taking on additional, significant amounts of downforce at different speed levels are something I had never considered but makes perfect sense. How would you dial this in?


4. Canards
...I am running a single canard. I have contacted the manufacturer of my front aero package regarding the addition of a second vortex generator to couple with the canard. Just spitballing it, you think these are good for only about 15 to 20 pounds downforce as is?



5. Diffuser winglets
...Based on your feedback, I believe my winglets are too tall - correct? Would I be better with a trimmed carbon fiber sheet coming off the front diffuser 3/4 to 1.5" tall? Would any shape be better than another (e.g. rectangular vs an angle mirroring the canard as I have it now)?



6. Front diffuser
...Correct me if I am wrong, but my set up is a front diffuser and not splitter, correct? My diffuser goes back just past the engine bay and is vented with strakes along the mid section and edge.


The center of the diffuser is upturned more than the edges, is that what you meant by a step up?


Would my set up be benefited by adding a splitter?


7. Flat bottom
...I do not have a flat-bottomed girl; just the front and rear diffuser. I have considered building a flat bottom panel with a few sheets of alumalite


8. Rear diffuser
...Is my diffusers rolling edge adding more drag than down force? I am not sure of the angle but will add that to my to do list. I can adjust the angle and will work towards getting it to a 12 to 14 degree angle. Is this a good design or useless without a flat bottom? Are the benefits negligible or do you think the effects are negative?



9. Vertical vens / strakes
...I will add getting the spacing length and width of the strakes to my to do list, in addition to the measurements of the diffuser


10. Side skirts
...Are these doing anything or strictly for looks?


Would a side diffuser design like this help, hurt, or do nothing? I have been working with a carbon fiber manufacturer to build a set out of carbon fiber angle and alumalite, but have only theorized on the benefits



Please feel free to tear my car apart, red ink everywhere!

As you mention David, aerodynamics is pure science - I just don't have the understanding at this point to fully be able to dial in my car


Here is what I have for my current aero package level setting to do list:
1. Wing height and angle reference guide
2. Push down on wing on rear hatch, does it move or is it solid?
3. Distance from roofline, height delta from roofline
4. Vehicle rake angle, height front of side skirt and rear of side skirt
5. Front diffuser angle edges, angle center, edge height front and rear, center height
6. Diffuser winglets height, angle
7. Front canard angle primary front, to angle over tire
8. Rear diffuser angle, width and length, height front and rear
9. Diffuser strake angle, width and length, height front and rear
Anything else you would add to this list?


Suppose this was your car and you had a track day coming up, what different configurations would you test in attempt to better the balance?

Best of luck at COTA!


Mark - I will be at Whiskey hill two days before you (10/14) with NTD. Looks like Dan signed up as well

I have just begun to pick up greater speed arching turns 1-3 from my approach at Palmer 1 to Palmer 2, and I know I have room to go - felt a little unnerving at first, but now feels amazing!

I would love to do a full test day. I try to squeeze as much seat time as I possibly can with our HPDEs, but it would be great to tweak things here and there come in after a few laps, tweak than try some more. I am going to look into a few more in the spring


Thanks again gentlemen for your feedback, I really appreciate it!

I know this post was tearing my car down, but I am open to making this thread a full COM aero discussion. Post up your set ups and your findings


Cheers!

[breakaway500]

Great looking car! I will let Dave answer all those aero/race questions as he has the hands on experience. I'm but an explorer.. Thanks for posting that NTD day..I somehow missed it..plenty of room..let's hope they don't cancel it..

[962porsche]

when I get back from circuit of the Americas I will take a look at the car and what you have done for aero .
I do not tear peoples cars apart with things they have done that's if you haven't slammed the thing to the ground have wheel and tires that stick out 5" past the wheel opening and have 6 degrees of camber and use wards like dope .
I have this body RX7 in my sim program now but if I could get a straight on side photo and one straight on of the front and rear also I then can scan it into the program to take a quick look to see just what the air flow is over and under the car .
the down side of not being able to 3D scan the hole car is looking at it from all angles so knowing exactly what the air flow under and over the top of the car is doing is out .
if you do take photos send them to my email dkbautosports@gmail.com

on a side note I wanted to instruct at the PALMER NTD event but I will be out at Laguna Seca testing for the IMSA event so I hope I can get to instruct for them next season .
I love instructing it's a total blast and gives allot of self satisfaction the smile on a students face is priceless !

[Rotary-Amuse]

Thanks Mark! Have you ever run an NTD event? This will be my first one. I was on the fence between running COM's last event of the season up at NHMS and NTD's Palmer event, but we decided on Palmer since it will be a few of our guys first track days and they wanted to stay closer to home. There should be about five to seven of us joining you and Dan

Want to repost your picture of the new aero set up on the Atom? I think the link is broken



Dave - I will be heading up to the garage this coming weekend and will be able to grab those pictures and get them over to you. Thanks

What IMSA team do you work with? I am watching COTA qualifying now and will catch the race later this weekend (the race is live now, but I don't have FS1 so have to catch the races after they're posted up online - I just do my best to keep my blinders on in the interim to not see who won)

I love Whiskey Hill, but would choose Laguna Seca if given the option too; MRLS is definitely one of my bucket list racetracks. Hopefully I'll be able to catch up with you at one of these events to thank you in person

[breakaway500]

I've run a couple of NTD events..pretty much SOPs for HPDEs...25-30 minute sessions,,depending on overall numbers.
Hoping to take the Focus on some new suspension to WH on the 14th. With it's new aero enclosure..it seems to need more wind control as the car felt pushed around over 100mph. I'm installing "racing" coil overs and heavier springs. Nothing too serious..


I see the Atoms wing pic still,so must be something to do with the address I used to post the picture. I know enough about computers/internet to be a danger...