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Old 12-09-2016, 03:24 AM   #16
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Originally Posted by Nerobro View Post
you're playing in some weird places for reynolds numbers. Short chords make wings act strangely...
Will try again with a spoiler with the same chord as before, in that example I just chopped the standard spoiler. Se attachments for quick jab at a same chord 3 element wing.

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Originally Posted by Skiddins View Post
Think the wing should be somewhere inbetween with regards to it's position.
More like this;
Thanks, redid the tests. Now in this thread you have three spoiler/air dam placements.
http://www.rctech.net/forum/attachme...-overhang2.jpg
http://www.rctech.net/forum/attachme...-spoiler-v.jpg
http://www.rctech.net/forum/attachme...ts-tc-full.jpg
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Little aero secrets-tc-mid-placed-spoiler-v.jpg   Little aero secrets-tc-mid-placed-spoiler-pr.jpg   Little aero secrets-tc-3-element-same-chord-v.jpg   Little aero secrets-tc-3-element-same-chord-pr.jpg  
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Old 12-09-2016, 03:52 PM   #17
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Armed with hundreds of simulator runs, ten's of different configurations I can share the following theories.

Our car's simple bodyshell is too specific in how it delivers amounts of downforce. You have a small window of tuning, mainly you buy another shell if track conditions don't suit the downforce package you choose. The tech is stale and bodies looked the same thing since many years ago. The reason was that small changes like spoiler aft-rear placement and wicker bill height were simple and the implications easy to understand. As a manufacturer (I am making my own vacuum forming machine) if you changed something in the nose section you changed too much in the rest of the bodyshell, making the understanding of changes difficult and complicating the process of setting a package to track conditions. That's why bodyshells have few variations in nose and rear shapes, or roof height moved aft-rearwards to "tune" which should shed/add rear downforce. Going by the rules there is still a bit of room for improvements and of course copying what are current Touring (WTCC for example) car aero designs. With current designs is like only a one or two bodyshell designs work but in reality they have small flaws that have great repercussions. The improvements, if made, wouldn't cost more to the racer. On the contrary, like current designs, once the shape is perfected in real world tests or CFD software it's valid for some time, or until the ruling body decides to change rules affecting body dimensions. I know I can design a body that would increase downforce by a great margin and didn't even look that different to current gen shells. Like this one and anotha one. Disregard wing mounting, could be done in my 3d printer easily but let's stay with the current mounting design for cost sake. See where they differ from current gen bodies? There are subtle cues and it's not the fastback style that would help in reducing drag but look closely

Hope to give the right people good ideas. I know some old bodyshells had things that were lost because the ruling body decided 2 doors weren't enough. If one would put a Astra side by side with a current gen (meh, should I say a T2 approved body since there was little variation in approved bodyshell design and the old gen was just before the Stratus?) the difference in cabin volume isn't much different. The body is an almost perfect representation of the 1:1 version raced on BTCC.

Thank you for reading this crazy rambling, it's open for debate as always and has the intent of learning and sharing. Any question make sure you understand what I wrote and that English is not my native language.
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Old 12-10-2016, 12:09 AM   #18
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Is there the possibility to analyse our actual bodies full 3d scanned and give out numbers that can be compared for downforce levels and drag?
I dream of a list of all our favorite racing shells.

@3dtooth: Did I try to say that actual Tc scale bodies would create more downforce?
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Old 12-10-2016, 01:09 AM   #19
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Is there the possibility to analyse our actual bodies full 3d scanned and give out numbers that can be compared for downforce levels and drag?
I dream of a list of all our favorite racing shells.

@3dtooth: Did I try to say that actual Tc scale bodies would create more downforce?
Yes there is a possibility by using a 3d scanner but I don't have access to one. Hands on approach by testing real size design cues directly on track is resource intensive... You can try for yourself but it would take days and would be best done in a controlled environment, like an indoor track with hygrometer and thermometer to know conditions of a run.

I don't know, did you? I did say, if elements from the Speed6 and Stratus 2.0 were further developed.

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Old 12-10-2016, 11:58 AM   #20
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Great work here. I've always wondered, RC bodies are "shells" what the effet of open under carriage had on the net effect?

Now the nerd comes forward, It would be cool to have the aero/cf # come with the bodies.
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Old 12-10-2016, 01:00 PM   #21
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Great work here. I've always wondered, RC bodies are "shells" what the effet of open under carriage had on the net effect?

Now the nerd comes forward, It would be cool to have the aero/cf # come with the bodies.
Thanks for stoping by.
First, the farther away a aero surface is from ground the lesser the effect it can have. Like wings or diffusers. So by having open and small chassis the smaller the suction effect the chassis has if it's sealed in the front* and sides.
Second, you guys keep asking for numbers but they are impossible to replicate closely on this simple software.

*if using ground effects like the lotus 78 had then one would not seal the front, wouldn't be difficult to do on a slim chassis and the amount of downforce would be tremendous!
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Old 12-10-2016, 07:49 PM   #22
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I really like the work you did with this free 2D CFD program, very interesting. So if you assume a 1cm wide element (your 2D image but 1cm wide to give it a 3D approximation), can you get drag numbers and center of pressure?
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Old 12-11-2016, 02:44 AM   #23
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I really like the work you did with this free 2D CFD program, very interesting. So if you assume a 1cm wide element (your 2D image but 1cm wide to give it a 3D approximation), can you get drag numbers and center of pressure?
Thank you.
Unfortunately no, this only works with 2D images, sides, top or bottom. I think removing the tires by lowering the entire body we can have a better visual of where the pressure zones will act. I'm away from home but what I know is that the area above the splitter and the spoiler are where the pressure is higher, with great rear bias.

Also, I could try to do side flow once I understand which color to use. That way it would look more 3d.
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Old 12-11-2016, 03:58 PM   #24
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Actually the area of higher pressure in the front is highlighted in the attached image. It's a bit above the bumper.
Limitation of the program, I tried and it can't compute more than silhouettes

Still, the drag induced by the high "wing" our cars run is something I want to tackle on by glueing a "wing" directly on the boot lid. So many ideas...

Look what I've found. That would mean 755grs of DF, at 108km/h if I understand... The music is Kavinsky - Nightcall (been into NewRetroWave lately).
+ YouTube Video
ERROR: If you can see this, then YouTube is down or you don't have Flash installed.
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Last edited by 30Tooth; 12-11-2016 at 04:35 PM.
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Old 12-12-2016, 08:36 AM   #25
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Originally Posted by 30Tooth View Post
Thanks for stoping by.
First, the farther away a aero surface is from ground the lesser the effect it can have. Like wings or diffusers. So by having open and small chassis the smaller the suction effect the chassis has if it's sealed in the front* and sides.
Second, you guys keep asking for numbers but they are impossible to replicate closely on this simple software.

*if using ground effects like the lotus 78 had then one would not seal the front, wouldn't be difficult to do on a slim chassis and the amount of downforce would be tremendous!
Really cool info, thanks for putting all this up for us all to see. What about air trapped under the body? That's something I have always been curious about, but I don't have a feel if the flow is turbulent or detrimental to handling. When I was racing my TC3 back in the day I experimented with fans and cooling ducts, but never tried anything to increase downforce.

On a project in the future, just for kicks I'm going to create a lexan chassis protecting under tray which flares out to a diffuser past the end of the chassis. Then maybe put some vents in the rear of the body. As long as the air under the body can escape I don't see how this could be harmful.

Keep up the good work!
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Old 12-12-2016, 09:20 AM   #26
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Thanks, I appreciate it and means a lot to me.

Air trapped under the body can only be stagnate or create lift (if it's the same speed as the outer air). That's why we have a rear bumper opening to let that air get out and create a little suction, not much and if the front splitter and side skirts would do their job and cut most of the air getting in then that difference in air velocity (or speed) would be greater and if the rear spoiler created a suction that would suck air from the bumper opening now that would be a team working together (there is enough data on the pics I posted to help anyone achieve this ). If you need help just post here I'll do my best to help.
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Old 12-12-2016, 10:20 AM   #27
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your simulation is assuming a flat bottom... does it assume a stationary floor as well?
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Old 12-12-2016, 10:35 AM   #28
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your simulation is assuming a flat bottom... does it assume a stationary floor as well?
It can assume a shaped bottom too, stationary like the car not getting lower from downforce?
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Old 12-12-2016, 11:01 AM   #29
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Thanks, I appreciate it and means a lot to me.

Air trapped under the body can only be stagnate or create lift (if it's the same speed as the outer air). That's why we have a rear bumper opening to let that air get out and create a little suction, not much and if the front splitter and side skirts would do their job and cut most of the air getting in then that difference in air velocity (or speed) would be greater and if the rear spoiler created a suction that would suck air from the bumper opening now that would be a team working together (there is enough data on the pics I posted to help anyone achieve this ). If you need help just post here I'll do my best to help.
Yea I hear what you're saying. Also as I'm sure you already know there are certain race cars and road cars which have blown diffusers with fans to increase the flow velocity and help increase the downforce they produce. It would be interesting to see what aero tweaks could be done with the cooling fans we run. It would be really nifty to have the fans channel air past the ESC and motor and out the back in such a way that the flow does something positive for the car's handling.
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Old 12-12-2016, 12:47 PM   #30
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Yea I hear what you're saying. Also as I'm sure you already know there are certain race cars and road cars which have blown diffusers with fans to increase the flow velocity and help increase the downforce they produce. It would be interesting to see what aero tweaks could be done with the cooling fans we run. It would be really nifty to have the fans channel air past the ESC and motor and out the back in such a way that the flow does something positive for the car's handling.
The Chaparral 2J and the Brabham BT46b comes to mind! You wouldn't need much to start, you just want to get the most air to exit by the cut in the bumper and to keep air from entering by the sides. That way it would increase inside bodyshell airflow.
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