Endplates

Magpie · Postby **Magpie** » Mon Mar 14, 2016 8:07 am

Do endplates actually improve downforce?

Singular would say yes - Upgrade the endplates on your APR GTC-200 wing! Up to 40% increase in downforce on the outer 1/3rds of the wing – that is a 25% increase in overall downforce! Raise your top speed! Add these endplates and reduce your wing’s angle of attack to achieve the same downforce as before with far less drag. With the standard APR endplates, the wing is less effective near the outer sides. These improved endplates were designed around real-world airflow and pressure data to improve the downforce and efficiency of your wing. http://www.singularmotorsports.com/product/singular-motorsports-endplates-apr-gtc-200/

When considering wing end plate size, bigger is better until you get to crazy big, like larger than F1 wing mounts/endplates so my 12x12in end plates (max NASA PTx size) will not be trimmed. The large end plates also act as yaw stabilizers in a skid. Another possible benefit is they may act as vertical wings and create low pressure on the wing side of the end plate which would augment the low pressure created by the wing. As air on the side of the car flows past the hard top it will tend to flow inward over the trunk lid. This inward flowing air will flow around the end plate like a flat wing with high pressure on the outside and low pressure on the inside surface. https://robrobinette.com/S2000Aerodynamics.htm

These are photos comparing the APR endplates that came with my wing to the Singular ones. Are the singular ones better, can't comment really as my lap time are not consistent enough to make an assessment? Maybe at the next full day general practice I will swap endplates and see if there is a major difference.

IMG_1305 by Eipeip, on Flickr

IMG_1304 by Eipeip, on Flickr

IMG_1303 by Eipeip, on Flickr

IMG_1302 by Eipeip, on Flickr

project.r.racing · Postby **project.r.racing** » Mon Mar 14, 2016 10:40 am

Didn't you learn after the suspension thread? :lol:

The end plates are all fine tuning for a pooftenths improvement.

One of your examples talked about airflow over the wing. This is correct. But you'd really have to be in a wind tunnel to accurately measure it. A big wing would require a big endplate to prevent any air slipping out the side of the wing. How much air slips out the side depends on air coming over the roof, height of wing above bootlid etc. Did I mention wind tunnel? :lol:

The ones like the singular ends do look like they have had some science and money throwing into it's developement. But looks moreso like wind resistance has been taken into consideration more than anything else. The original ARP ones aren't designed for airflow over them and are thick compare to other options.

Magpie · Postby **Magpie** » Mon Mar 14, 2016 11:09 am

I'm over suspension now, at least for the moment

Agree end plates are fine tuning and some people maybe looking for just that. I'm more concerned about consistency (and not mentioning suspension)

plohl · Postby **plohl** » Mon Mar 14, 2016 11:40 am

You dirt sprinting this coming Sunday magpie?

Sent from my SM-N9005 using Tapatalk

Magpie · Postby **Magpie** » Mon Mar 14, 2016 11:42 am

No will be at Morgan Park (SDT training day).

Dan · Postby **Dan** » Mon Mar 14, 2016 7:48 pm

I'd be interested to see the drag numbers they got in the model they used when determining the '25% extra downforce' since on a 3D wing like the GTC series wing it has a dramatically higher AOA on the outside edge (14 degrees more than centre on the GTC-200 and 15 degrees on the GTC-300) so by my thinking they are forcing more air onto the most aggressively angled section of the wing.

I looked at the models in the 'competition car aerodynamics' book and their models showed only a 10% increase in downforce with the largest endplates they modelled (600mm) so to get 25% increase in overall downforce and 40% in the outer 1/3's of the wing they would be doing significantly better than that but I wonder how much that comes at the expense of drag.

It would still probably be more efficient but I wonder by how much (the same models I mentioned before in 'competition car aerodynamics' showed a 10% improvement in efficiency across the wing with a 400mm endplate which was the peak efficiency gain by end plate length).

madjak · Postby **madjak** » Mon Mar 14, 2016 7:53 pm

Can we move all the discussion to one thread? Lets keep all talk here as endplates vs AoA are all interlinked. Magpie, are you trying to confuse us all or something?

Here is my post from the other similar thread:

The end plates are stopping the high air pressure on the top of the outer edges of the wing from leaking around the sides to the low air pressure below. If you have no end plate then a good part of the length of the wing is less effective as the high pressure and low pressure air can mix effectively losing that force downwards on the wing. Add a well designed end plate and you can keep the pocket of high pressure on the top and low pressure on the bottom from mixing.

The end plate also forms a nice little vortex swirl where the laminar flow along the side of the car mixes with the deformed air from the wing which reduces drag a lot. So a well designed end plate not only increased downforce but reduces drag at the same time.

I think the claim of 25% might be accurate if you think of it at 12.5% increased downforce on each tip of the wing.

the whole 3D wing thing is only useful because the air coming over the rooftop is heading downwards over the boot, whilst the air that skips around the side of the roof is near horizontal. A good designed 3D wing is keeping the airflow over the wing more consistent over the length of the wing. The idea being that you can prevent the middle section going into stall if the AoA is too steep. If you put a 3D wing high enough though it will be worse off than a 2D wing as the airflow high is flatter. So generally, low wing mount = 3D wing, high wing = 2D.

Magpie · Postby **Magpie** » Mon Mar 14, 2016 8:09 pm

Not trying to confuse

I think that whilst wind/end plates are holistic you can change both. This was more about 'statements' made by the makers of end plates.

Does the forum need its own aero thread to keep this in one place?

Dan · Postby **Dan** » Mon Mar 14, 2016 8:19 pm

Yeh, I see that you were just posting their info.

I was sort of playing devils advocate and the point I was making is that the 25% claim could be accurate and these bigger endplates would almost certainly be more efficient but I'm a bit dubious about the efficiency gain when someone advertises a percentage of extra downforce and then just says it provides less drag rather than providing a drag or efficiency percentage in the same way they provide a percentage for the downforce increase.

How much more efficient these endplates are than increasing the overall angle of attack of the wing is something we'll probably never know.

madjak · Postby **madjak** » Mon Mar 14, 2016 8:24 pm

I think the bigger end plates look better anyway. Whether or not they work better is secondary! 10-15% is probably realistic... who knows really?

Good aero design is a little bit science, little bit experience... but that all gets trumped by trial and error in the end anyway. Unfortunately ever car is different so changing minor things on the car can greatly effect the wing. The theory should still work though and be used as a starting point. Good designed endplates will increase downforce by maximising the area where the high and low pressure areas act and reduce drag by creating effective vortexes... however a wing mirror in the wrong spot might could destroy any gains... who knows until you find a metric to datalog options. (aka ride height)

I just think these general rules apply though:
Mount the wing as high as possible - to get into clean airflow
Mount the wing as far back as possible - to get more leverage on the rear
Run as wide as wing as possible - more surface area = more downforce
Run the wing just under the stall point - trial and error, keep raising the AoA until you get less traction, more drag
Run end plate designed for the wing (with some sort of testing) - The Singular end plates look far better than the APR end plates to me.

btw, you know if the endplates are working well because the bottoms will bend in towards the wing as the low pressure area 'pulls' on them.

In tweaking the aero on your car, you want to balance the front and the rear. So if you are finding the rear stepping out on big sweepers raise the AoA until it doesn't. If you get understeer then lower the AoA until it stops, or put on a bigger splitter.

Magpie · Postby **Magpie** » Mon Mar 14, 2016 8:33 pm

Dan · Postby **Dan** » Mon Mar 14, 2016 8:38 pm

Yeh I like the look too!

For the record I'm probably going to get a set of Singular endplates anyway. I need to go to Vegas for a conference (plus skiing for a couple of days) on the 29th and I'm thinking about getting some goodies sent to my hotel from Goodwin

Here's the page of analysis of endplate lengths from that book if anyone's interested:
http://i.imgur.com/IIOlun6.jpg?1

rascal · Postby **rascal** » Mon Mar 14, 2016 8:59 pm

madjak wrote:I just think these general rules apply though:
Mount the wing as high as possible - to get into clean airflow Only if you are talking 2D wings. 3D wings work better out of the direct air stream
Run the wing just under the stall point - trial and error, keep raising the AoA until you get less traction, more dragTrial and error until drag penalty exceeds gains from xtra grip. May be nowhere near almost stall, and will change track to track

In tweaking the aero on your car, you want to balance the front and the rear. So if you are finding the rear stepping out on big sweepers raise the AoA until it doesn't. If you get understeer then lower the AoA until it stops, or put on a bigger splitter.Or you hit the limit of splitter size. I think most cars struggle to match a big ass rear wing and the limit of rear aero is determined by front aero to maintain balance ]

zossy1 · Postby **zossy1** » Mon Mar 14, 2016 9:57 pm

^^^ I agree with most of this - except the comments re running the wing close to stall.

I recall in some of my studies in the deep past, a standard platform airfoil stalls at or near 16 degrees AoA to the line of air flow. That is an absolute bucketload of AoA for a race car wing to run, and is (I expect) why most 2D wings (Gt250 is one example) aren't designed to allow for more than 15 degrees AoA.

Most setup info I've read on single element 2D wings mounted on tin tops suggests that, for a good quality, well sized 2D wing, somewhere between -2 degrees and 6 degrees AoA will deliver best results (depending on front aero downforce). Most folks start at zero AoA, and work to balance from there. Running 10+ degrees would induce significant drag and require equally massive power to overcome it, and a huge front air dam to provide sufficient balancing aero.

Having said that, I've seen cars running big AoA at the track - guys who should know what they're doing too. I wouldn't - I don't have 350whp - but YMMV.