Rear wing downforce comparison sheet

[Lennart]

If you are interested you can send me an STL file of the rear wing I should "test" and I include it in the sheet.
The maximum width of the wing is 30cm and I only tested the wing and its endplates. Without the mounts and a car.

All the simulations were made with the simscale free trail.

I ranked them by efficiency. If you have twice the efficiency you can get double the downforce for the same drag or half the drag while keeping the same downforce.

The numbers are at 35m/s or 126km/h air speed. And the wing is tested in free air, so if mounted on a car it will have less downforce and be less efficient.

The limitless wing does not have accurate dimensions, since I don't own one.

The 3D-printed airfoil wings can't replace a strong injection molded wing on a bashing rig. But for on-road cars, they could be interesting.

The front wing's effectiveness will be greatly reduced when attached in front of a car, which blocks and slows down the air behind the front wing.

 

[Dales396lt4]

Aerodynamics on the rear wing and front canards made a huge difference in speed. 11 miles an hour to be exact (99 to 110) by cutting the rear spoiler down two notches all the way across and three notches down on the front canards, aerodynamics plays a big role in running fast cars. Interesting work thank you. I Look forward to seeing more input.

 

[dure16]

Aerodynamics on the rear wing and front canards made a huge difference in speed. 11 miles an hour to be exact (99 to 110) by cutting the rear spoiler down two notches all the way across and three notches down on the front canards, aerodynamics plays a big role in running fast cars. Interesting work thank you. I Look forward to seeing more input.

Was this on a limitless? Would mind sharing pics of what you changed?

 

[Dales396lt4]

I can do that, but it won’t be tonight

 

[dure16]

I can do that, but it won’t be tonight

No rush. I appreciate it.

 

[Dales396lt4]

Yes, it is a limitless V2

I’ll take a better picture later that shows the difference between stock and what I did.

 

[Greengaunja]

Man, I'd like to be able to input and receive data on my wing. Made it with two decks(for rigidity) with the upper deck adjustable. When I shared pics, one of my FB groups got into this huge debate as to whether or there were any aerodynamic value to the upright fins on the upper deck. And as I read, I'm thinking I only put those there cause it looked cool.

 

[Lennart]

upright fins on the upper deck

The Glickenhaus prototype car has fins too

If you cant 3D model the wing you could upload a sketch with all the dimensions. Or I just do a simulation with a flat 3mm plate angled upward.

Does anyone have a limitless wing 3d model or measurements? I could also compare it in stock form and when cut down.

 

[Vedak]

I like where this thread is going.

 

[Dales396lt4]

If jenny's was cheaper, I would just send you the whole set but $70 I’ll have to look at other options.

 

[Lennart]

have to look at other options.

I will try to make a 3d model with pictures from the internet.

It is cool to see that the 4 piece big wing creates a big tip vortex. The wing itself could be more efficient if the wings would have a shallower angle.

 

[Dales396lt4]

The lower you trim it the lower the angle. There are lines on the spoiler that you can trim down to each one appears to be about a quarter inch in height. There are quite a few of them. In front has very steep angles and they’re very tall. I think cutting them down makes the biggest difference, you’re not pushing a sheet of plywood through a windstorm.

 

[Greengaunja]

View attachment 352805 The Glickenhaus prototype car has fins too

If you cant 3D model the wing you could upload a sketch with all the dimensions. Or I just do a simulation with a flat 3mm plate angled upward.

Does anyone have a limitless wing 3d model or measurements? I could also compare it in stock form and when cut down.

Here's what I did:

I might grind another half inch off the 7075 mounts because when I look at it this way(ground level) it seems too high.

 

[Dan B.]

Here's what I did:
View attachment 353307View attachment 353308View attachment 353305

I might grind another half inch off the 7075 mounts because when I look at it this way(ground level) it seems too high.
View attachment 353309

View attachment 353306

You did an outstanding job on that wing. Nice work.

 

[LibertyMKiii]

I don't want to come across as rude or arrogant, but also want to take an opportunity to educate when possible. I fully realize aerodynamics are a highly misunderstood topic.
Using a carbon fiber plate is basically like using the rectangle block like shown in the 2nd image.

 

[Dan B.]

I don't want to come across as rude or arrogant, but also want to take an opportunity to educate when possible. I fully realize aerodynamics are a highly misunderstood topic.
Using a carbon fiber plate is basically like using the rectangle block like shown in the 2nd image.

View attachment 355323

Totally agree, but I haven’t found any actual airfoil plates for sale. I believe most everyone in the hobby who is making their own wings is using CF plate, or some variety of plastic or nylon. They could be 3d printed of course, but a lot of guys don’t have that resource available.
On the ones I’ve done, all were built using CF plate and I’ve rounded and finished the leading edges on a belt sander. Almost like a Kamm tail, but without the taper in the material.
I know your experience in this realm is pretty extensive and your explanations are for the most part irrefutable, so don’t think I’m arguing your point on any level. I would just submit that the majority of people in the hobby, whether building wings for show or go, don’t really have the resources to perfect them and thus the comparison of various existing real-world designs can be quite helpful to us in deciding the most efficient design to employ from those available.

 

[Lennart]

The simulation just finished. As expected the air separates on the underside.
But the efficiency is better than I thought with 2.6 and equal to the stock limitless wing.
Just keep in mind when the wing is attached to a car the airflow will come from a different angle with different results.

They could be 3d printed of course, but a lot of guys don’t have that resource available.
On the ones I’ve done, all were built using CF plate and I’ve rounded and finished the leading edges on a belt sander. Almost like a Kamm tail, but without the taper in the material.

I also think rounding the edges, especially on the underside of the plate is beneficial.

If you don't have a 3D printer or superb carbon fiber manufacturing skills you can't get hold of an airfoil wing.

 

[LibertyMKiii]

Totally agree, but I haven’t found any actual airfoil plates for sale. I believe most everyone in the hobby who is making their own wings is using CF plate, or some variety of plastic or nylon. They could be 3d printed of course, but a lot of guys don’t have that resource available.
On the ones I’ve done, all were built using CF plate and I’ve rounded and finished the leading edges on a belt sander. Almost like a Kamm tail, but without the taper in the material.
I know your experience in this realm is pretty extensive and your explanations are for the most part irrefutable, so don’t think I’m arguing your point on any level. I would just submit that the majority of people in the hobby, whether building wings for show or go, don’t really have the resources to perfect them and thus the comparison of various existing real-world designs can be quite helpful to us in deciding the most efficient design to employ from those available.

Rounding the leading edge is a great mod that many over look. I think the size of these wings makes it less critical than a RC airplane but still good things to think on.
It starts to get exponentially harder to make but you could bond multiple plates of CF and then create the shape/profile by sanding away material. Just remember to wear PPE.

The NASCAR style gurney flap / spoiler are interesting to study also as they don't require airflow to pass below the element. They purposely disturb the airflow at the rear of the car. I have wondered how they might work for RC cars.

 

[Dan B.]

The NASCAR style gurney flap / spoiler are interesting to study also as they don't require airflow to pass below the element. They purposely disturb the airflow at the rear of the car. I have wondered how they might work for RC cars.

View attachment 355344

When I was in the sports car/road-race world the trend was for installing what we then called “whicker bills” on the back of the wing. It was usually just a thin strip of aluminum that was slightly (30°, +/-) angled up and was believed to create so much “dirty air” behind the car that it would disrupt the aerodynamics of the car behind it. And again, they were very short. I don’t think I ever saw one that was more than 30-40mm high. I don’t know how effective they actually were, but many teams swore by them. We didn’t have the computer modeling or sims back then, so who knows.

 

[LibertyMKiii]

I made this one for the Limitless 2 years ago. No one ever noticed but it looks like stock...
Sent it over to you Lennart if you want to check it out. I never tried it in a simulation so maybe it sucks