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Old 05-25-2009, 01:42 PM   #31
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Originally Posted by CanyonCarverR1 View Post
I'm no expert, but having just a rear diffuser does not create ground effects. You have to have "tunnels" under the chassis to capture the air to be diffused. Look at pictures of full size race cars that have ground effects.
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The low pressure area in the "tunnels" is where the car is sucked down onto the track.
ConyonCarverR1, I totaly agree with what you are saying about the area under the car to creat downforce. When downforce is created, it can help or hurt the car in the way that the car handles. Too much downforce on the front and the car and the car can NOSE OVER going into a turn if the suspension isn't able to handle it. I think that was the case with running the front diffusers on the NT1. I also have tested a full underside kit on the car, going all the way out to the edge of the body. (in the past) What I had discoved is that if you hit something on the track like a dogbone, the nose of the car can catch too much air and the car will lift up and the car can become airborn. With using just one area of the car, like the back of it, you can target the area of the car that can benifit the most from directing the air under the car into a stablizer, not so much to create the downforce, but to direct airflow.

The thread was actually about rear diffusers. Mounted at the rear underside of a Car, to clean up air flow and reduce drag, reduce lift and add downforce. The effect of a diffuser couldn't be considered as stand alone; it's effect is dependent by the way the rear wing works, the effect of rotating tires, side skirts, the angle divergence, and how it influences the pitch an roll behaviour of the car. The ideal diffuser would have a divergence angle starting at about 7 degrees, but increasing smoothly up to around 20 degrees.

I'm not an expert, but with a little bit of time spent on the internet reading about how air reacts to passing over surface areas, and how to control it, led me to the original design. Then talking to others that have worked on this before, has helped me come to the final design that we tested. I'm not saying that this will be the final design. Nor am I an expert, but I will be working on a few more ideas this week to test this coming weekend to find the best possible combination. I will say that I have already abandoned the idea of a front and side splitter/diffuser. The bodies we have today give all the downforce needed. The diffuser is intended to take waisted and/or trapped air flow and direct it into someing of benefit while not to bottle up air flow going through the car.

Thinking about this, if a 1/10th car is traveling at 50mph, at scale speed, that would be 500mph. Push air at 500mph under a real car and what happens?
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Old 05-25-2009, 01:46 PM   #32
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Adding a rear diffuser will do nothing to the handling of the car, the air under the chassis must be controlled to create a low pressure zone!
I dissagree with this though. I know what the car handled like, and I know what tire wear was like as well. I have REAL RESULTS to base this on. As well as 2 others that tested this with me.
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Old 05-25-2009, 02:06 PM   #33
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Thinking about this, if a 1/10th car is traveling at 50mph, at scale speed, that would be 500mph. Push air at 500mph under a real car and what happens?
Speed is speed and cannot be scaled. A 1/10 car going 50mph is still only going 50mph. Time cannot be scaled.
Good luck with your project, and I'll be watching your progress.
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Old 05-25-2009, 02:10 PM   #34
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Just skimmed through the ROAR rule book and didn't see the restriction on underbody aerodynamic devices. I know it used to be there but it looks like it's gone.
I looked at IFMAR rule book and it is forbiden, in chapter 5 of the tech specs
it states.....

5.18 under body/chassis aerodynamic aids of any nature are not allowed

so for any IFMAR sanctioned events (i.e. the worlds), it's a no no

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Old 05-25-2009, 02:52 PM   #35
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I looked at IFMAR rule book and it is forbiden, in chapter 5 of the tech specs
it states.....

5.18 under body/chassis aerodynamic aids of any nature are not allowed

so for any IFMAR sanctioned events (i.e. the worlds), it's a no no

AFM
I knew it was not allowed, IFMAR rules are a little more specific. I have to look it up and post it here.
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Old 05-25-2009, 03:42 PM   #36
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I knew it was not allowed, IFMAR rules are a little more specific. I have to look it up and post it here.
You got to much time on your hands
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Old 05-25-2009, 06:27 PM   #37
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You got to much time on your hands
Yea, I know....................page 18 of the IFMAR World Championship Rules 1:10 IC Track Racing and Technical Rules, rule 5.18 Under body/chassis aerodynamic aids of any nature are not allowed.
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Old 05-25-2009, 06:47 PM   #38
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Yea, I know....................page 18 of the IFMAR World Championship Rules 1:10 IC Track Racing and Technical Rules, rule 5.18 Under body/chassis aerodynamic aids of any nature are not allowed.
But not ROAR, so keep it up James.
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Old 05-25-2009, 07:07 PM   #39
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Originally Posted by CanyonCarverR1 View Post
Adding a rear diffuser will do nothing to the handling of the car, the air under the chassis must be controlled to create a low pressure zone!
Then why do F1 cars have diffusers? F1 cars since the mid 90's have been flat bottomed. The underside of the car is nothing but a flat plank of wood. The diffuser is an extension off of the back of that plank.

Of course, the ultimate diffuser is something like a 1/8th body. Keep the nose close to the ground to keep as much air as possible out from under the body and have the back end wide open to suck what little air is there out.
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Old 05-26-2009, 12:29 AM   #40
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But not ROAR, so keep it up James.
Isn't there a rule that if the ROAR has no rule stated the IFMAR book must give an answer?

I know a lot of Europian countries are using EFRA rules or have a set of their own and if not provided the EFRA rules are counting.
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Old 05-26-2009, 02:54 AM   #41
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Yea, I know....................page 18 of the IFMAR World Championship Rules 1:10 IC Track Racing and Technical Rules, rule 5.18 Under body/chassis aerodynamic aids of any nature are not allowed.

I really wonder how they are going to agree if its a performance enhancement or not.. simply put, what if i modify the A-Arms to have an aero package on them.. but simply state that this is for strenght?
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Old 05-26-2009, 03:36 AM   #42
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Isn't there a rule that if the ROAR has no rule stated the IFMAR book must give an answer?

I know a lot of Europian countries are using EFRA rules or have a set of their own and if not provided the EFRA rules are counting.
Just read the book from cove to cover to find that, but it doesn't have it in there. In the past, I believe it did have it, as I do remember something like what you stated.

The only rules that have anything to do with aerodynamic devices are:

This rules is listed under bodies:
5.4.8 Bodies must remain as originally approved. Flaring front fenders or making any other aerodynamic modification is not permitted.

6.5.1 Definition: Wings are aerodynamic devices attached to vehicles to increase down force and traction when a vehicle is traveling at speed. The dimensions of wings vary depending on the class of racing, and are described in class rules or specifications.

but this does not address chassis attatched devices.
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Old 05-27-2009, 05:30 AM   #43
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rcfoolz,
what type of rear diffuser style are you trialing? the F1 style(1 page back), or the more common touring car style diffuser(which is what most 1:1 cars have).

ive been trialing out some front diffuser stuff with my nitro. i made the underbody perfectly flat, with some lexan plastic, and added a front lip with aero vanes in it. the lip extends from the chassis, past the foam bumper and sticks out from underneath the front of the body. with the addition of some small canards i found it helped keep the nose down during high speeds(only in a straight line). i had to get the front lip as low as possible for it to show some difference. however it gets easily damaged...
i havent yet moved onto rear diffuser, so im interested in what your working on.
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Old 05-27-2009, 01:13 PM   #44
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rcfoolz,
what type of rear diffuser style are you trialing? the F1 style(1 page back), or the more common touring car style diffuser(which is what most 1:1 cars have).

ive been trialing out some front diffuser stuff with my nitro. i made the underbody perfectly flat, with some lexan plastic, and added a front lip with aero vanes in it. the lip extends from the chassis, past the foam bumper and sticks out from underneath the front of the body. with the addition of some small canards i found it helped keep the nose down during high speeds(only in a straight line). i had to get the front lip as low as possible for it to show some difference. however it gets easily damaged...
i havent yet moved onto rear diffuser, so im interested in what your working on.
I had a set of front diffusers that had atteched to the front A-arms and also tried something that went under the front bumper, but I found that anything put on the front of the car causes understeer. As for the rear, it is more traditional style for touring cars with the upkick and canards,but they are not set to 0-degrees (strait in line with the chassis) They are angled slightly. I will be posting pics again in a few days after I have had a time to revise and do some more testing.
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Old 05-27-2009, 03:23 PM   #45
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Performance question: Under chassis aero package....Is it worth it?-dxf-streto-vortex-megatron-chassise28099.jpg   Performance question: Under chassis aero package....Is it worth it?-dxf-streto-vortex-megatron-chassise280992.jpg   Performance question: Under chassis aero package....Is it worth it?-dxf-streto-vortex-megatron-chassise280993.jpg  
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