Rc Car Aero

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RickRick
4
Joined: 30 Aug 2011, 17:21

Rc Car Aero

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Hi Guys i was after some thoughts on Rc Car Aero effects

I'm running 10th scale off road buggys, the minimum weight for the class is 1475g most cars are 1500 ish, we use a large rear wing around 170mm wide, with a very steep angle on the rear. i'm sure, and most people agree that when the wing comes off it does have an effect on handling, changing the balance of the car
Also runnin small, but again steep angled front wings is becoming more popular.
What i'm wondering is if i can figure out how to make something, if small wings on each hub would be worth the effort, i've probably got about 30mm on each wheel to play with.

Smokes
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Joined: 30 Mar 2010, 17:47

Re: Rc Car Aero

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2wd or 4wd?
You will probably have binding issues with the front hubs and grass dirt clay binding the rears etc. You are better of looking at the predator X11 and the previous evolution of for buggy aero. It is a great car but extremely fragile. this introduced front wing in the 1990's, inboard suspension and aero wishbones it shrouded the inside of the wheels to improve aero.

RickRick
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Joined: 30 Aug 2011, 17:21

Re: Rc Car Aero

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either, i've got 2wd and 4wd, it would have to be mounted so it moved with the steering, and carefully planned to ensure it cleared at full travel ect.

I've actualy got a X11 and it's a lot tougher than the old preds, hardly broke anything when i was running it, now using schumacher sx3 and sv2

Bazza
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Joined: 13 Nov 2011, 13:01

Re: Rc Car Aero

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I'd hazard a guess and say that the biggest change probably isn't from downforce primarily, but from changes to the centre of pressure. Unfortunately good documentation is a lot harder to find for c.o.p than it is for downforce and wing profiles, but it really can be every bit as useful for 'cheating' at vehicle handling.

If you're adding a big rear wing, then it's dragging the cop up and backwards quite a bit, and if the front wing doesn't impact on front drag a whole lot (it would be smoother at least than the usual front end?) then you would probably see not a whole lot change with the cop (but the added benefit of whatever front downforce you can grab).

RickRick
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Joined: 30 Aug 2011, 17:21

Re: Rc Car Aero

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maybe some pics of the normal things that we're using

http://www.petitrc.com/setup/xfactory/X ... index.html

http://www.oople.com/forums/showthread.php?t=97245

http://www.oople.com/forums/showthread.php?t=31166

and i'm looking at the options of getting small wings mounted directly onto the uprights as close to the wheels as i can

Smokes
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Joined: 30 Mar 2010, 17:47

Re: Rc Car Aero

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Mounting to front wishbone would be a good idea though if the car flips that wing will bind, or if you run in to the back of another car the wing will bind. Most guys have gone cab forward to get more air to stick to the rear wing. try using the old yokomo plastic wing that were popular in the 1990's.

The other option is to build an Aerofoil profile wing with a suitable angle of attack to get some front DF. Or add more weight to the nose of the car. Or try Fabs Kyosho Mid custom special for 2wd.

But remember more wing = more drag = a motor running hotter....

thisisatest
18
Joined: 17 Oct 2010, 00:59

Re: Rc Car Aero

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in the early 90s, people started to make airfoil shaped rc car rear wings, for buggies and for 1/10scale road pan cars. i stepped away from the scene and when i looked back in, they were nowhere to be found. i wonder why?
one thing that always bothered me about the wings was how they were mounted- sometimes on the rear shock towers, partially obscured, or with extremely bulky hardware. whatever you use to mount the wings ought to complement the wing's purpose.

Smokes
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Joined: 30 Mar 2010, 17:47

Re: Rc Car Aero

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I Think because the wing are considered sacrificial part, many driver don't want to pay a fortune for a replacement wing. Also a stiff wing can have the potential to do some serious damage to other cars the track and the marshals. Has lead to current aero developments in RC car racing, Cab forward body's different lexan wings with various profiles etc.

gato azul
70
Joined: 02 Feb 2012, 14:39

Re: Rc Car Aero

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It's a long time since I raced RC-cars, and I never did off road stuff, but I think trying to develop a airfoil profile for these sort of application has little benefit.

I just looked at some off the photos, you posted and from where I sit I don't think you would gain much by developing a "wing" for this application - not in terms of overall downforce, compared to the spoilers/airdams you run now.

In a nutshell, you just try and "shovel" as much air on top of the spoiler as you can and try to keep it there with the side fences/endplates to get some stagnation pressure.
Nothing wrong with that, it's a bit "draggy" but that's about it.
If you would go to the trouble and develop a "real wing" (airfoil profile) for a buggy, you will have problems, to keep it at the optimum angle of attack most of the time, because the car jumps and bounces/pitches around quite a bit.
I doubt, you would see large improvements in overall downforce, and just to gain some points in efficiency (L/D) seems to be a lot of cost/trouble for very little gain.

I don't think, you will gain much from mounting the spoilers directly to the un-sprung parts/uprights etc.
you will get the same downforce either way, and I don't think, you have problems with bottoming out/ or worry too much about rake changes (change in the pitch attitude of the car).
The reason F1 or real race cars (on circuits, not off road racing) are concerned about this is, because they generate most of their downforce with the underbody/diffusers an/or front wings, which both operate in ground effect, which are extremely sensitive to changes in ride height/ground clearance and angle/pitch.
If you want more downforce, make the spoilers larger, if this is permitted by the rules (I don't know).
Alternatively, if you are "crazy" enough, and the rules permit it, you could try what used to be, maybe still is, I don't know
a solution found in slot car racing - open class

look at the car in the middle&right
Image

they used to run longitudinal air dams, to try and increase the pressure on top of the whole car surface.
at speed this air dams would bend down sideways a bit, increasing the absolute planform area.
as a side note, as you see, they did run skirts a well to seal the floor to the ground and run between 1-3 mm ride height (dependent on tyre wear).
These things were seriously quick at the time > 100km/h

Have fun & good luck

Smokes
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Joined: 30 Mar 2010, 17:47

Re: Rc Car Aero

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I would guess it would be better to model a car up in 3d cad and see how the air flows in cfd first.

gato azul
70
Joined: 02 Feb 2012, 14:39

Re: Rc Car Aero

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I thought that you guys may like this.
o.k. it's not a Buggy, but someone tried to model a RC-car

http://haagringnews.blogspot.com/2011_0 ... chive.html

Image

joewoods
0
Joined: 16 Aug 2012, 14:12
Location: Oxfordshire

Re: Rc Car Aero

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Bazza wrote:I'd hazard a guess and say that the biggest change probably isn't from downforce primarily, but from changes to the centre of pressure. Unfortunately good documentation is a lot harder to find for c.o.p than it is for downforce and wing profiles, but it really can be every bit as useful for 'cheating' at vehicle handling.

If you're adding a big rear wing, then it's dragging the cop up and backwards quite a bit, and if the front wing doesn't impact on front drag a whole lot (it would be smoother at least than the usual front end?) then you would probably see not a whole lot change with the cop (but the added benefit of whatever front downforce you can grab).
Pretty clear thought and it is very difficult to to go for good documentation!

ffreitas
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Joined: 29 Dec 2012, 03:27

Re: Rc Car Aero

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I was the one who did the cfd " virtual wind tunnel" simulation pictured above. I'm flattered to have my analysis mentioned in a forum like this. You can find the complete results of my simulation here: http://haagringnews.blogspot.com.br/p/o ... s.html?m=0.

The model I used was a 1/27 Kyosho mini-z, I believe some of the general findings would apply to other models as well.

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flynfrog
Moderator
Joined: 23 Mar 2006, 22:31

Re: Rc Car Aero

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ffreitas wrote:I was the one who did the cfd " virtual wind tunnel" simulation pictured above. I'm flattered to have my analysis mentioned in a forum like this. You can find the complete results of my simulation here: http://haagringnews.blogspot.com.br/p/o ... s.html?m=0.

The model I used was a 1/27 Kyosho mini-z, I believe some of the general findings would apply to other models as well.
Welcome to the forum nice work

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