Recently got dimensions of an Aeromotion’s wing and figured I would do an endplate study. It’s been quite a while since I’ve done one of these!
So far I have gotten rave reviews on my APR endplates, Voltex endplates, and most recently the 9-lives endplates. My goal is always to try and have as efficient of a car as possible. So while some setups will create more downforce, if it doesn’t improve our L/D I usually don’t put it on my car. What a more efficient endplate allows you to do is decrease angle of attack, but still achieve the same downforce levels at a previously higher angle of attack. This allows you to keep the same aero balance of the car, but get some free lap time on the straights. In that regard, some would say I subscribe to the current design philosophy Ferrari employs, even if they’re not doing so hot!
Anyways, let’s jump right in!
I have to mention - I love Russell’s Evo 10. The small airdam to run the front splitter lower to the ground, the dual front dive planes, hood exits, and blockoff plates are all really functional. I was contacted by him to try and get a little more downforce out of the rear wing as he is starting to max it out. I’ll leave some pictures below to show you the car these endplates are being designed for.
The first thing I did was run just the airfoil in a free stream, with no endplates. I like to do this in order to see the pressure distribution of the airfoil to better understand it’s characteristics. Even before seeing the results, I can see what the design philosophy of this wing is. It is clearly designed to be uber efficient, with the sacrifice of top end downforce (aka exactly what I like!). The pressure surface has almost no camber to it, while the suction surface has a fairly subtly leading edge to discourage separation. If you look at the streamlines below, you can see there is a tiny laminar bubble forming on the pressure surface, while the suction surface separates towards the trailing edge. This would not be the case if I was running an infinite wingspan, but I am running it at 1650mm (same as Russell’s wing).
In hindsight I should have removed the endplate mounting holes before doing this run, but I don’t think it would have made a huge difference. I was mainly looking for a visual on the streamlines.
The next thing I did was gather baseline results. I added the stock endplate and ran the wing at 80/100/120/150MPH with and without a gurney flap. Russell is currently running the gurney, but still has some AOA left. I usually recommend always using all available AOA (before stall) before touching a gurney flap. While a gurney immediately adds downforce, it is not as efficient as adding AOA.
Before I continue, I usually want to be fairly confident in the baseline results, or else the data does not mean much. I could not find CFD data on Aeromotion’s site, but Russell had some on hand. The trends actually matched my results very closely so I was confident I was on the right track!
You can see the results I go below. All of these results are at 0 AOA. I have not had time to run at different AOA yet, but I am confident it will have a fairly linear trend from what I’ve seen compared to the stock Aeromotion’s data.
There are a few things that I am very impressed with already. If you look at both of the results below, the efficiently stays almost exactly the same throughout. Most wings that I have investigated have a varying efficiency as the speed increases. The reason I really like this is because the wing is very linear and predictable. After perusing through their site I see that they also sell an active wing package with the same airfoil. After seeing that this wing makes total sense because it makes it really easy to adjust aero balance. Since it has a linear trend, it’s very easy to calculate how much wing you need in different power limited or grip limited situations. I really wish that active systems were legal in more amateur racing series as I would love to be able to test their system.
Aeromotion’s data sent to me
I tried several different airfoil shapes to see what the wing would react to the best, but most were not performing as well at the stock wing. So I decided to just try and optimize the current shape as much as possible. I incrementally increased endplate volume in each direction (forward/aft/top/bottom) and stopped when the wing would no longer react positively. That led to the shape shown in the figure below.
While bigger is usually better with endplates (because it acts in the same way as increasing aspect ratio), it is not always the case. It usually compromises efficiency as you add surface area that isn’t being utilized.
After some more tweaking, I finished at the final shape shown below. As you can see, it has the same silhouette as the current endplate, just bigger. Russell pointed out to me that they matched the bottom of the endplate to the pressure distribution of the wing, which resulted in a drag reduction. I hadn’t heard of this before so I tried it with and without the curve and it really did work (learn something new everyday)! I noticed a noticeable drag reduction with that design detail. Yet another detail which really impressed me with Aeromotions!
After all is said and done, you can see the final results below. I did not expect such significant gains! It’s probably the most I’ve seen from all of my endplates. The best part is the linearity of the wing was maintained, so it should be just as easy to adjust as ever for the desired aero balance.
These took about 3 weeks to finish and over 100 CFD runs, but definitely learned a lot in the process. The next step is to get some of these machined!
Next in line is the APR GT250. Sorry for the long wait, but we’re almost there!
UPDATE: Finished product
