Wings and mounting

[Pearldrummer7]

Hi all

Finally looking to pull the trigger on a wing and splitter for my R (thank you, tax return!). I am torn between the straight GT-250 (less drag), and the FFR provided GTC-300. Same price point, looks like mounting is similar too.


Which sparks my next question: I saw Brandon and Chad's mounting solutions. Any other ones around? I'm a okay welder, I suppose I could try to find a nearby shop that could fabricate something. Are there any accepted "yays" or "nays" for wing mount?

[Mulry]

I like the flat wing a lot better and it seems more suitable for the 818 body. The GTC300 is more suitable for coupe cars that need that twisted outer section to make them effective due to the airflow around the rear glass/hatch area IMO.

That said, I'd really like a wing with built in nuts to make it easier to change a Gurney at the track. I've seen how they do this on prototype cars and it's stupidly easy -- just different height carbon strips -- but you need a nut embedded in the wing to hold and locate them. The APR wings just use double-sided tape to stick the Gurney flap on the wing, which makes it messy to change once you have one on there.

[Santiago]

I like the flat wing a lot better and it seems more suitable for the 818 body. The GTC300 is more suitable for coupe cars that need that twisted outer section to make them effective due to the airflow around the rear glass/hatch area.

Definitely. I also favor a straight wing for an 818R for the same reasons.

GoodAero has a really slick gurney slot that you can quickly slide in/out different size flaps. Big money though, and I wouldn't spend it just to get an adjustable gurney. Still, you've got to love elegant design solutions.

There's a lot of tuning potential in the wing's angle of attack, you just pay a greater drag penalty for it (relative to gurney size adjustments). For most folks, I suspect this gets down to some pretty fine grains of sand. A good straight wing getting nice air is going to go a long way, especially since it seems the rear of the car isn't showing signs of being a trouble spot (aerodynamically speaking).

Best,
-j

[RetroRacing]

We are picking up our straight wing (gt250, 71") in the morning!!! We will post picks of our mounting, behind the car, brackets that extend out the rear either side of the trans to support long vertical aluminum "blades" behind the trunk lid. Lightest and strongest solution we could find, and leaves the top trunk/valance open to service the engine during long races. Mocking them up in plywood, then sending out for water jet

By moving the wing back, we can run less angle for more downforce, due to the lever effect (increased distance to the rear wheels) so less vertical load to support, so lighter mounts, etc.

Does leave the wing and supports open to rear end collision damage, just means we have to drive faster to keep people far enough behind us.....

[Pearldrummer7]

I like the flat wing a lot better and it seems more suitable for the 818 body. The GTC300 is more suitable for coupe cars that need that twisted outer section to make them effective due to the airflow around the rear glass/hatch area IMO.

That said, I'd really like a wing with built in nuts to make it easier to change a Gurney at the track. I've seen how they do this on prototype cars and it's stupidly easy -- just different height carbon strips -- but you need a nut embedded in the wing to hold and locate them. The APR wings just use double-sided tape to stick the Gurney flap on the wing, which makes it messy to change once you have one on there.

Definitely. I also favor a straight wing for an 818R for the same reasons.

GoodAero has a really slick gurney slot that you can quickly slide in/out different size flaps. Big money though, and I wouldn't spend it just to get an adjustable gurney. Still, you've got to love elegant design solutions.

There's a lot of tuning potential in the wing's angle of attack, you just pay a greater drag penalty for it (relative to gurney size adjustments). For most folks, I suspect this gets down to some pretty fine grains of sand. A good straight wing getting nice air is going to go a long way, especially since it seems the rear of the car isn't showing signs of being a trouble spot (aerodynamically speaking).

Best,
-j

I would love a better Gurney changing system, but for now I think I have adjustment overload between suspension, wing angle, etc. Thank you two for the confidence boost on the flat wing, though. It makes sense in my head.

We are picking up our straight wing (gt250, 71") in the morning!!! We will post picks of our mounting, behind the car, brackets that extend out the rear either side of the trans to support long vertical aluminum "blades" behind the trunk lid. Lightest and strongest solution we could find, and leaves the top trunk/valance open to service the engine during long races. Mocking them up in plywood, then sending out for water jet

By moving the wing back, we can run less angle for more downforce, due to the lever effect (increased distance to the rear wheels) so less vertical load to support, so lighter mounts, etc.

Does leave the wing and supports open to rear end collision damage, just means we have to drive faster to keep people far enough behind us.....

Retro, I'd love to see this. I'll be awaiting the thread This sounds like what I want to do

[RetroRacing]

Since it will be in the water jet cutter computer, if you like it, Im sure they could make you a set. Our mounts to the frame will be welded, but you could make a set that bolts to the frame very easily.

[Pearldrummer7]

Since it will be in the water jet cutter computer, if you like it, Im sure they could make you a set. Our mounts to the frame will be welded, but you could make a set that bolts to the frame very easily.

That would be amazing. I would be totally down to pay you to ship me a mount

[07FIREBLADE]

Interesting. Would like to see how you make the mounts.

[Scargo]

I expect that I will have a strong interest in the wing mounting solution you will be getting cut. I also do TIG and fab work. I appreciate the offer and look forward to seeing what you come up with.
This GT-250 wing by APR? One I was considering... How does it compare, price-wise to other decent ones?
gt-250-adjustable-wings_02.jpg

[C.Plavan]

Get the flat wing. Also, since you will be driving your car on the street. Make a real rear bumper for safety (While you are there)

[Pearldrummer7]

Get the flat wing. Also, since you will be driving your car on the street. Make a real rear bumper for safety (While you are there)

Chad- I actually made a rear bumper for street inspection that bolts in. Just a welded steel assembly. I was debating making it a dual-use bumper/wing mount.


Also, I've been in talks with a company called AJ Hartman Racing on a custom wing. Fully adjustable gurneys(sp?), CF, super strong, designed to whatever I want. Guy said $1,750 as spec'd (70", adjustable angle of attack and gurney, mounts wherever I choose). Seems fairly reasonable to me. It'll be between that and the GT-250. Non adjustable gurneys would be $1,500, so similar price to the GT-250.

[Scargo]

For club racing and down (meaning cheaply, without unlimited resources and engineers), how do you measure what a wing is contributing (helping /hurting) other than SOP, lap times or top speed? How do you tune it to the car and differing tracks?
Are there transducers, pressure measuring devices, etc. that can be added to data collection that are affordable or rentable? Other things like monitoring tire temps and pressure for changes?
Does it hurt performance if everything coupled is not perfectly rigid or does it just slow the effect until everything gets loaded?
If you have a good way to measure loading or force then are there some guidelines for what you want? Surely, at some point you have too much tire wear or too much traction for HP, if there is such a thing. And that's assuming you can match the force in the front.

[Sgt.Gator]

@Scargo: Lap times ultimately rule. Of course you have to eliminate all the other variables. If you can get a test & tune day without a ton of track traffic you do test with the splitter on and off, wing on and off, and different wing angles of attack. With a good data logger this becomes easier because you can analyze the performance not of an entire lap, but in segments. You'll see exactly that the wing slows you down 3 mph at the end of the front straight, but adds 4 mph thru the high speed sweeper that comes up next.

As far as measuring devices: Yes there are, potentiometers on each coilover. This makes measuring the downforce at each wheel easy. Attach the top and bottom of the potentiometer to the CO, or any part of the suspension that moves under compression on one end stays fixed on the other. Make a run down a long straight. Use a data logger to record the suspension compression. Make aero change, run again, look at the data. It's possible to calculate exactly how many pounds of downforce you are creating by measuring the distance compressed and multiplying by the spring rate. You can also see that if you add downforce to the rear wing, you are almost for sure reducing downforce on the front tires. You of course have to eliminate the noise created when going over bumps, so it's best to find as smooth a straight as possible.

Here's a potentiometer for the AIM datalogger: https://www.pegasusautoracing.com/pr...Product=MC-206



The AIM ones are very expensive, but it's possible to find much cheaper ones. There's really not much to them.

You aren't concerned with too much traction or tire wear. The tradeoff is drag vs downforce. It's possible to generate a lot of downforce with huge wings, but your top speed is so slow your lap times suffer. Some tracks with short straights, low top speeds, and lots of curves you will crank up the downforce because the high top speed doesn't last long enough to be a big factor. Some autoX cars look like a Fokker Triplane! Other tracks with long straights and only a few corners you will go with less downforce for more top speed = faster lap time.

This is a great book, everyone who races should get a copy (the new third edition): http://www.amazon.com/Competition-Ca.../dp/1845847768

[Scargo]

Thanks for the info. Book ordered. I guess I'll wait on other neophyte questions till I've read more. Seems like I have a book by everyone else. Might as well have one by McBeath...
Am looking for cheap or used pots.
In my STi efforts to date, I've just emulated what I've seen the big boys doing with no real understanding of how it's affecting the car. I've never done data-logging with the current aero I have on the STi so, with other issues I've had, like the wrong transfer gearing when I built a close-ratio box and changing a whole bunch of things at one time, I don't know how it's helping me. One reason I've held off on adding a Gurney flap.

[C.Plavan]

One thing about all this discussion- Don't over think it. We are not professional race teams. Try a couple different wings settings, then stick to the one that is most comfortable.

[Scargo]

I appreciate you reminding me, but I am retired and I have not that much else to occupy my mind. I am also a big DIY kind of JOAT and frustrated college engineering school dropout.

I am trying not to paint myself into a corner with the car, where it has little value or requires a huge investment to be raced. I am trying to invest in design features and hardware that will readily transition into an ST2 car, thus having some potential value, if the car proves capable. Though I don't see me racing it WTW, I am putting in all the safety equipment required by NASA.
So, I may just be playing, but I am eyeing the requirements of what it takes to be competitive in ST2 or ST1. I was sold when I saw FFR run away from everyone on their first real race at Watkins Glen. You have also shown that the car can be fast. Thanks for being a pioneer.

[Santiago]

+1 on the McBeath book, it's really very well done. I've read a bunch of aero articles and McBeath is one of the best intro books around. I like that his writing style there is very much in the "problem solving" mode: "theory says this, experiments yielded this, now let's figure out why the two don't jive." He does this without totally overwhelming the reader with formulas.

Once you've digested that, move on to Katz, Race Car Aerodynamics. Many of the technical images you'll find on the web explaining basic aero-principles came from this text. It's really very good; an excellent intermediate level book (i.e. be prepared to start digesting formulas...the waters get a little deep, but nothing to drown in).

Then you move on to selected chapters in the Bible of our world...Race Car Vehicle Dynamics, Milliken & Milliken. This is what they feed the little sharks being raised to compete in Formula SAE. The Milliken's are the pioneers of serious engineering study of all things race car...they are our Kronos and Zeus. This is high-level stuff, and you better have your math chops sharpened...but damn is it good.

Best,
-j

[Sgt.Gator]

Thanks for the references Santiago!

[FFRSpec72]

Hi all

Finally looking to pull the trigger on a wing and splitter for my R (thank you, tax return!). I am torn between the straight GT-250 (less drag), and the FFR provided GTC-300. Same price point, looks like mounting is similar too.


Which sparks my next question: I saw Brandon and Chad's mounting solutions. Any other ones around? I'm a okay welder, I suppose I could try to find a nearby shop that could fabricate something. Are there any accepted "yays" or "nays" for wing mount?

VRaptor makes a mount (you do the welding he supplies the parts and instructions), I have it on mine and so do a few other 818R around here

[RetroRacing]

Here is where we got to on the weekend. Supports will go out tomorrow for water jet, will put some holes into the uprights to lighten things up a bit, and will decide if we need any lateral support once they are installed. Using 3/8" thick 6061.
The mounting angles are really simple. We welded ours, but if we were to make them bolt in, we would make the uprights bolt horizontally through the steel with a lift and push tab front and back. The wing sits 32" center of wing to center of rear wheel, and is approx. 1.5" above the roll cage. The uprights are each one piece, we just used wood to template the larger portion of the vertical for ease. At 71" the wing is exactly the same width as the car!
With the inside of the uprights flush with the outside of the straight rear bars, and using 3/8" material, the center to center wing mount measurement is 17"
Hope to have them back by the weekend, will post more pics and what they cost us then.
IMG_0688.JPGIMG_0690.JPGIMG_0692.JPG

[RetroRacing]

IMG_0692.JPGIMG_0694.JPGIMG_0695.JPG

[Pearldrummer7]

6061 will be perfect for this. You think just those two mounts will be sufficiently strong?

I would be interested in buying this if you made me one.

[Pearldrummer7]

VRaptor makes a mount (you do the welding he supplies the parts and instructions), I have it on mine and so do a few other 818R around here

Very cool. It's a lot of welding for someone without a welder and with little welding skill. It's an option, though!

[RetroRacing]

We figure 250lb, 32" away from the axle (fulcrum) would be the norm, but I'm running it by my engineer to see what he thinks (since I have one on staff). I'm more concerned at this point about the frame, we plan on doing some vertical load testing to measure force to wheel, and identify the point at which we will see deflection. easy to do with some weights and scales.

[Mitch Wright]

Looks pretty trick.

[C.Plavan]

Don't get rear ended by a Miata Looks good.

[Scargo]

Criticizing and second-guessing is easy. I'll go ahead and ask why the supports are not shorter/mounted higher? What about going in at the highest possible point, other than there is no pre-existing structure? Then it might be that supports could be wider and you get away with 1/4" thick Al.

[FFRSpec72]

The wing may be actually to far back and thus the front down force has to greater

[Pearldrummer7]

The wing may be actually to far back and thus the front down force has to greater

Or, you could have a proportionately smaller wing out there....less drag, right?

[RetroRacing]

You got it, no structure up there, putting one in adds weight up high in steel, not equal to 2 pieces of alum. Looking at the chart for drag and downforce for this wing, the mechanical advantage of placing the wing back, and running 0 degrees, is huge compared to running it further forward for the same resulting load on the rear wheels. Not saying we are going to be balanced, but take a look at Chads angle of attack (a question I have been wanting to ask for comparison) and you will see where I am trying to go with this. The support weight difference and or width difference is negligible once you notice that the APR mounts are 1/2".....
Hey, it's a work in progress, will probably have to change it all later, but that's what it's about, try it, prove or disprove, better it.

[FFRSpec72]

Hey, it's a work in progress, will probably have to change it all later, but that's what it's about, try it, prove or disprove, better it.

yep, totally agree ! I will be running the GT250 wing. What are you going to be running in the front, just the spoiler ? or canards also ?

[Pearldrummer7]

Hey, it's a work in progress, will probably have to change it all later, but that's what it's about, try it, prove or disprove, better it.

Fantastic quote. Yes, that's true! For all of us. You guys are doing really important work, Retro. I like your mounting idea and would like to buy your mount to try myself. It's more what I was thinking.

yep, totally agree ! I will be running the GT250 wing. What are you going to be running in the front, just the spoiler ? or canards also ?

Personally I'm going to run just a splitter at first and add canards if I feel I need more downforce.

[RetroRacing]

Canards and splitter, with all of the work we are doing on the undertray, we are hoping to get some help there too. Dropping off the template today, will let you know what they quote me

[FFRSpec72]

Canards and splitter, with all of the work we are doing on the undertray, we are hoping to get some help there too. Dropping off the template today, will let you know what they quote me

So are you blocking off the under car air exit with the splitter and forcing everything up and out the hood vents ?

[RetroRacing]

All of the air from the rad goes up through the hood. All underside air stays under the car and out the diffuser, engine is flat bottom and sealed as well with a drop down and a funky shape under the car....will post pics

[FFRSpec72]

Hi all

Finally looking to pull the trigger on a wing and splitter for my R (thank you, tax return!). I am torn between the straight GT-250 (less drag), and the FFR provided GTC-300. Same price point, looks like mounting is similar too.

You can get the GT250 wing from VRaptor for less than FFR price point and in different lengths. The center drive 818 has been playing with both wings (GTC300 and GT250).

[Scargo]

I sure did like the looks of the Ferrari wing supports of their Daytona car. To the wing issue: I forget... Did FFR wind tunnel test a straight wing? Could it be that getting one higher and farther back would favor the straight wing? Could it be if you have a minimal windscreen and reduce or eliminate the passenger side bulge that it would also benefit the flat wing? As I get it the FFR wing is more for a coupe. All the upward protrusions may give a similar wind disturbance. In an R this might be something that could be addressed.

[RetroRacing]

Our mounts were screwed up by the waterjet guy, they cut too much out for the upper mounts, should be ready on Friday, will post pics. Did you notice how the wing mounts on the Porsche cost them the race? Sometimes, simple is better.

[RetroRacing]

BTW, had to remove the trans due to some clearance issues with our hydrolic bearing clearance to the clutch. To remove the transmission, 10-15 minutes. back in again, two men who didn't remove it, 15 minutes. Remove 6 bolts, wing. Remove 4 bolts, rear fiberglass. remove 4 bolts, rear suspension, remove 3 hose clamps, intercooler-blow off valve. remove two -10 lines, oil cooler. remove 2 bolts, intercooler-oil cooler box. remove starter and trans bolts, remove hydrolic line for bearing, remove trans out the back.

Successful test! Now, add heat....

[FFRSpec72]

BTW, had to remove the trans due to some clearance issues with our hydrolic bearing clearance to the clutch. To remove the transmission, 10-15 minutes. back in again, two men who didn't remove it, 15 minutes. Remove 6 bolts, wing. Remove 4 bolts, rear fiberglass. remove 4 bolts, rear suspension, remove 3 hose clamps, intercooler-blow off valve. remove two -10 lines, oil cooler. remove 2 bolts, intercooler-oil cooler box. remove starter and trans bolts, remove hydrolic line for bearing, remove trans out the back.

Successful test! Now, add heat....

Very nice, throw out bearing had to be the biggest issue getting transaxle out