What's the logic/science behind the massive end plates?

 

Aerodynamic Yaw-angle stabilizers ...

 

I know on my wing the difference between the biggest size legal and U-Maryland style endplates was almost 80 pounds @ 60mph. U-Mayrland is know for having endplates so large that their cars can actually tip over in paddock in strong wing gusts.

 

The wing works by creating a higher pressure on top than on bottom. Without end plates, the pressure would "spill" over the edge creating a vortex, decreasing the downforce created and increasing the drag. Endplates prevent this. In general, the bigger the better.

 

I thought the end plates were supposed to have equal height above and below or biased towards being above the wing rather than below it.

I flew yesterday and the end plate on that wing was interesting. May just flip that design upside down and look fannccyyy.

 

Nope. There are books full of data (that I understand a small portion of) documenting why.

There is a Racecar Engineering article I have at home that had a lot of data on wing end plate depth. I'll scan it when I'm back there after Christmas.

 

Nope, you want it biased to the bottom. Because an efficient wing should create the majority of its force from the low pressure at the bottom of the wing, so you're going to have a lower pressure under the wing so air is going to want to flow into there from the sides more.

 

Sooo many of the wings on the market have terrible endplate designs. I have to assume it's just a trade-off decision; they assume the wing won't sell with a big form>function monstrosity of an endplate

 

Another reason end plates tend to be larger on bottom is because regulations often require that no part of the wing protrudes higher than the roof line of the car... and since you want the wing itself placed up high to get into the cleaner airstream, it doesn't leave much room for a large end plate above the wing.

A really good design would use uprights as end plates.

 

 

Many have no logic or science behind them

Large endplates seen on open wheel race cars do serve a purpose. It is intended to reduce the effect of the "dirty" air disrupting the airflow to the wing.

I like this because it could work and is funny!

This is kind of true and kind of not. The wing works by creating a gradient of pressure. The bottom of the wing (on a car designed to make downforce) will be doing most of the work. Aka more low pressure is created than high pressure. Endplates to help with spill over. Endplates cause vortices also. Also without an endplate, drag would most likely be reduced since the induced drag would be decreased. The efficiency of the wing however would drastically decrease. Bigger isn't always better. Proper analysis and testing is better.

Don't do this.

This is true.

This is true, most endplate designs are terrible. I would also go out on a limb and say most wing design are terrible also. They are taken off some racecar in the past without knowledge on the performance. Real racecars have specifically designed wings for their application. Changing applications might make the wing not perform properly.


The much greater low pressure at the bottom can be seen in this cfd pressure plot below. This is of a wing I currently in the process of designing (except now it uses my own airfoils that I designed instead of one available). The current iteration performs much better




This is a cfd pressure plot across the wing to show how endplates interact with the airfoil. This is my current single element design (endplates still being optimized). Also this is one tested on a Miata so this is not seeing all free-stream air.

 

Awesome!

 

The frontal area thing was more related to the turnbuckles/deflectors. That just looks like way more area than a bolthead/nut. Not significant from the normal perspective of frontal area/drag, but it looks like it could hurt the airflow in that region pretty bad and lead to a lot of separation farther back on the wing.

I've wondered how consistent the spacing is on that rear hole... mine was also really close to the wing and the bolt heads barely fit, but I guess I got lucky and the mechanics that worked on mine were gentle. I bet they used a standard hex bolt and nut on yours, which would definitely mar the wing if I tried it on mine. I use a socket head cap screw with a regular hex nut. With the SHCS, you can hold the nut from rotating with a wrench and then spin the screw with an allen key and not mar the wing. It's so close that the difference between a socket head and a button head is too much...

I hadn't thought about this being a problem with the bent brackets that you guys are using, but I see what you mean now that I think about it. One more reason I'm glad I just hacked some slots into my trunk lid and used flat pieces of aluminum for the uprights lol. Because racecar.

 

Haha. Smart guy You are right, they do, but they move the vortices away from the surface of the wing, reducing their detrimental effects.

Surprisingly not. Adding end plates to most automotive style wings actually decreases drag while increasing downforce. Free Lunch! woohoo!

Of course, but if you aren't going to do the analysis and testing (like 99% of the people here) bigger is better is a pretty safe assumption. The only big downsides to larger end plates are drag and weight, and if you are cool enough to use end plates as uprights, those disadvantages disappear

For some great info on the subject check out these articles from Racecar Engineering: http://www.rightwheeldrive.com/Aero_articles.zip

 

You are correct after I looked back at my old notes. Endplates increase the aspect ratio of the wing with decreases the induced drag.

 

It would most probably have little effect at the speeds we think about.
It's based on the logic when the center of aerodynamic pressure (seen from the side) is behind the center of mass the car will straighten when it gets sideways.
This was one of the design objectives with the COT body design and it apparently worked since the COTs could drift a lot longer when the old style spinned.

Usure if the Miata (with normal HT) is aerodynamically unstable or stabilized this way.
F1-style dorsal fin?

 

The big difference is that COT's are going 200+ mph and we are going a LOT slower.

 

 

Hustler likes wings with *****.

 

What's with the *****?