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Do rear spoilers actually work?

Old 12-22-2008, 11:44 PM
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Default Do rear spoilers actually work?

Not sure if this has already been discussed...but does a rear spoiler actually have any effect on the performance or are they just all cosmetic?
Old 12-23-2008, 12:01 AM
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Default RE: Do rear spoilers actually work?

I think the answer to that question is relative to the vehicle you are asking about. On buggies, truggies and MTs, I don't think they are a factor on the track or offroad just because the airflow needed to help push on the wing and keep the rear planted would require that the cars go much faster. I think they are mostly for looks, and buggies would just look silly without a wing.

On a street car that goes really fast, there is enough airflow that a wing can help keep the rear planted; so it is functional. The guys that run high speed runs need to have downforce on the rear and also on the front of the car to keep it down. Otherwise, air will get under the car and the car will just lift up for takeoff.
Old 12-23-2008, 12:08 AM
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Default RE: Do rear spoilers actually work?

Like Dale said, it's about the scale physics of the situation. I've noticed huge differences in handling on 1/5 scale cars based on body shape, but less so on smaller scale cars.
Old 12-23-2008, 12:16 AM
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Default RE: Do rear spoilers actually work?

i prety much agree with dale, i do have to say that a wing can do something, i remember on my truggy when i took the wing off, i was fighting for traction more than when i had it on, i agree, buggies/truggies wouldn't be what they are without wings, plus they protect the engine in a roll over...
Old 12-23-2008, 12:51 AM
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Default RE: Do rear spoilers actually work?

Wings on buggies definitely help.
Old 12-23-2008, 01:44 AM
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Default RE: Do rear spoilers actually work?

There will be more effect on a smaller, lighter, or faster vehicle. There will be less effect on a larger, heavier, or slower vehicle.
Old 12-23-2008, 10:00 AM
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Default RE: Do rear spoilers actually work?

Look at some of the micro-flying projects people have put together, the wing areas, plane weights, and speeds involved, and you will probably find that a 12 square inch wing doesn't do much of anything on an eight pound buggy at 30 mph. That same 12 square inch wind may indeed make a substantial difference in downforce at 60 mph on a five pound touring car, but the overall design of the car body will have much more of an effect. It has a lot to do with Reynolds numbers, which explain the volume of flow of fluids relating area and velocity, ie a wing 1/2 the size has to be moving 4x the speed to generate the same lifting force, and so on.(I do not pretend to know it all, but the principle is the important thing here) One thing wings and wing mounts are good for on offroad buggies is dissipating forces in a rolling/flipping crash. Ask me how I know.
Old 12-23-2008, 10:43 AM
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Default RE: Do rear spoilers actually work?

I would say that wings most definately help. The downforce applied will no doubt be small, but I am sure it does something. Anyone that has ever had a buggy or truggy wing come half off during a race can testify just how bad the handling becomes after that happens. The rear end on my buggy does feel a bit looser without the wing (I crash a lot, what can I say).

If nothing else, wings do give a certain amount of protection during an upside-down crash. One thing to consider - pro's use wings. If they did nothing, the pro's would lose them for the added power to weight ratio.
Old 12-23-2008, 11:06 AM
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Default RE: Do rear spoilers actually work?

^^^ I agree
Old 12-23-2008, 12:11 PM
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Default RE: Do rear spoilers actually work?

I agree big difference, "real" race teams may have a dozen different wings in there spairs bag just in case they want more or less rear end bite. Search for b 4 wing, you will probably find about 12 companies and 23 different designs lol.
Old 12-23-2008, 12:17 PM
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Default RE: Do rear spoilers actually work?

It does something......but not much...in my opinion.

Looking at the full scale car with a rear spoiler moving at 60MPH and then looking at the 1/8 scale RC rc with a rear spoiler moving at 60MPH.

I think the rear spoiler will have alot more effect on RC car than real car.
Old 12-23-2008, 12:58 PM
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Default RE: Do rear spoilers actually work?

1/8 buggies i never really noticed any differance but on 1/10 i can really notice. i run the jc 7'' rear wing on my CR and i get much more rear bite than i do without it.
Old 12-23-2008, 01:53 PM
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Default RE: Do rear spoilers actually work?

BuzzBomber almost has it. The Reynolds number relates the air density, velocity, and characteristic length (in this case, the chord length of the wing) to the coefficient of air viscosity. It helps us determine when flow changes from laminar (parallel to the chord of the wing) to turbulent (all over the place). So for cars that travel too fast, the flow becomes turbulent, and the wing actually performs little function. So wings have a somewhat constrained velocity interval at which they are effective.

I believe 1/8 buggy wings are pretty useful.
Old 12-23-2008, 03:18 PM
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Default RE: Do rear spoilers actually work?

The biggest reason I mentioned Reynolds was the correlation between wing area and effective velocity - I've seen a very real correlation between clipping off a few square inches of wing and consequent increased stall speed on some of my plane projects. I don't really know if the laminarity or turbulence of the flow even significantly comes into play with the cars given all the other factors, but that's just my opinion. With the cars, I think we're talking a lot more Newton, a lot less Bernoulli in this scenario in terms of lift/aerodynamics. These "wings" by their design have no real airfoil, sharp square edges for the most part, so I would imagine have turbulent flow and perform more like "deflectors". Look at the overall aerodynamics of an offroad buggy - parasitic drag everywhere(kind of off-topic, but there is a lot of drag on an open wheel design)! I think that the drag involved at higher speeds is probably just as important as any downforce generated, all that drag (and stabilizing area of the vertical side plates as well) behind the cg of the car will act somewhat like the feathers on an arrow. This might also be why the wings typically are designed so much larger proportionally on 1/10 scale cars compared to 1/8 scale - lower speed, not a whole lot of difference in mass. Balance has to have some effect as well. I know the wing and mount on my RC8 weighs several ounces - the balance upset alone would cause odd handling if you removed the wing and the CG shifted forward, I think. I could well be wrong on all counts, but my experience points to the lower speeds (perhaps 25mph or less) not depending much on aerodynamics unless you're talking about a very BIG wing; certainly anything approaching 50-60mph and I think it's a LOT more important. edit: Bottom line, yes I think they work, but not exactly the way many people expect. Sorry for the long, semi-nonsensical ramble. Have yourselves a happy Hannukah, crazy Kwanzaa, fabulous Festivus, or Merry Christmas as the case may be
Old 12-26-2008, 06:55 PM
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Default RE: Do rear spoilers actually work?

We put a wing on my cousins RC18T and you can feel a difference. The back tires have a little more traction and it is better for jumping.
Old 12-26-2008, 09:49 PM
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Default RE: Do rear spoilers actually work?

1/10 electric buggies are so lite that they need the wings, so yes they actually do something[&:]
Old 12-27-2008, 04:46 AM
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Default RE: Do rear spoilers actually work?


ORIGINAL: Yub, yub, cmdr!

BuzzBomber almost has it. The Reynolds number relates the air density, velocity, and characteristic length (in this case, the chord length of the wing) to the coefficient of air viscosity. It helps us determine when flow changes from laminar (parallel to the chord of the wing) to turbulent (all over the place). So for cars that travel too fast, the flow becomes turbulent, and the wing actually performs little function. So wings have a somewhat constrained velocity interval at which they are effective.

I believe 1/8 buggy wings are pretty useful.
Ah! Fluid dynamics!
I am so loving Wiki, they give college level and post grad engineering grade explanations of things:
http://en.wikipedia.org/wiki/Reynolds_number

For buggies and off road, I personally think the low speeds due to terrain and numerous turns negates the benefits of the wing. The wing and other ground effects work their best at speeds. And unless the wing is paticularly huge with a very steep angle, I doubt that it is possible for these things to reach speeds where the wing becomes useless from turbulent flow.

This is my guess as I have not actually sat down to calculate anything to back up my guess. By I stongly believe that these wings do little until teh RC hits the back straight and accelerates to speed in a straight line, then the down forces provided give the wheels more grip. But as soon as teh RC slows to enter a turn or is slowed by teh terrain, that downforce is reduced.

Old 12-27-2008, 09:18 AM
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Default RE: Do rear spoilers actually work?

it helps no matter what kind of car/ truck, fast or slow, heavy or light in one condition only, it helps protecting the protruding nitro engine when car/truck flipped.

seriously, aerodynamic will take effect when car/truck speed reached roughly 40 mph, then how much effect will be created will depend how much the car/truck weigh, it has more effect when truck/ car is airborne than in the surface...

also need to consider is how much the spoiler surface area, the deflection angle, and airfoil shape...the bigger surface area, more deflected and higher airfoil lift/drag the more effect....my 2 cents
Old 12-27-2008, 12:39 PM
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Default RE: Do rear spoilers actually work?

Wings on 1/8 scale buggies definately make a difference.
Old 12-27-2008, 01:18 PM
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Default RE: Do rear spoilers actually work?


ORIGINAL: wave waker

it helps no matter what kind of car/ truck, fast or slow, heavy or light in one condition only, it helps protecting the protruding nitro engine when car/truck flipped.

seriously, aerodynamic will take effect when car/truck speed reached roughly 40 mph, then how much effect will be created will depend how much the car/truck weigh, it has more effect when truck/ car is airborne than in the surface...

also need to consider is how much the spoiler surface area, the deflection angle, and airfoil shape...the bigger surface area, more deflected and higher airfoil lift/drag the more effect....my 2 cents
Very good point! Better to destroy a $15 wing than tear up the head of a race grade engine that could cost $75+ just to replace teh head!

As for the weight of the RC, on the ground, yes, the weight of the RC helps in giving grip to teh track. But the weight of teh RC does not increase the ground effect teh wing creates, it only adds its force to teh downforce created by the wing. So, adding the weight of teh RC plus the downforce of teh wing will give you the total force pushing the wheels down to grip the track.
The funny thing is the downforce of the wing is variable as you speed up and slow down. So, the total force on teh wheel to the grond will be higher at speed and lower when the RC is running slower.

Now, you also mentioned the wing's effect in mid-flight from a jump. Yes, I can definitley see where the wing is useful in helping control the RC's attitude in mid-flight. As teh RC is in teh air, the wing will tend to push teh rear of teh RC down in relation to teh center of mass, thus pitching teh nose upward. So, in mid-fligt, you will have to either gas it less to pitch the nose up, or if teh wing is doing too good of a job, you would have to hit the brakes to pitch the nose down back to level.

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