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Old 01-02-2017, 05:10 AM   #61
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Look how close are the skirts to ground.
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Old 01-02-2017, 06:42 AM   #62
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The Chaparral people used lexan skirts, and just considered them disposable. On the 2J "vacuum car".
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Old 01-02-2017, 10:51 AM   #63
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Chapman did not fail. He succeeded exceedingly. Lotus type 79 "ground effects" car, for example. Outlawed by FIA because too much corner speed. Ironically all drivers that drove it felt safer considering so much more grip. Enter the 1500 turbos, 1800hp 1100kgs, more died during this era, ground effects + the turbo monsters would have leap frogged lap speeds 30 years!
The aero skirts worked very well, aluminum sheets in a verticAL channel with Teflon (I would assume) runners. Google Venturi effect.
I was talking about his very unsuccessful car in the 1979 season not his brilliant Type 79 I don't need to google as I know a lot about it.

The problem is to convert this effect and the needed technology to a 1/10 rc tc. Even the real f1 cars of this era had many problems with skirts getting stuck or damaged. Now I (we) want to make it work in a much smaller scale doesn't make this task easy at all. I have to think how to prevent it getting stuck while still seal it properly and make it tough & light. Ideas welcome!

I also don't think that giving up on suspension won't hurt less than the now enhanced aerodynamics will better the laptimes. But it is worth a try. I will prepare the car to try it. It would be awesome if it worked, but I can't think how.
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Old 01-03-2017, 10:58 AM   #64
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Had the closed undertray mod on my mind for several years now and finally found the time and courage to try it. The whole thing weights 105g and is made of 1mm thick Makrolon. Not perfect, but this was what was available. The car now perfectly matches the minimum weight rule of 1350g. Not perfect either is where I try it: On an Indoor track. Outdoor would be better suited for the higher speeds...
Enough whining! Here some pictures:







Nice work wtcc, this is getting in the ballpark of what I'm considering.
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Old 01-03-2017, 12:31 PM   #65
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Originally Posted by wtcc View Post
I was talking about his very unsuccessful car in the 1979 season not his brilliant Type 79 I don't need to google as I know a lot about it.

The problem is to convert this effect and the needed technology to a 1/10 rc tc. Even the real f1 cars of this era had many problems with skirts getting stuck or damaged. Now I (we) want to make it work in a much smaller scale doesn't make this task easy at all. I have to think how to prevent it getting stuck while still seal it properly and make it tough & light. Ideas welcome!

I also don't think that giving up on suspension won't hurt less than the now enhanced aerodynamics will better the laptimes. But it is worth a try. I will prepare the car to try it. It would be awesome if it worked, but I can't think how.
Turnbuckles the length of the shocks lower the car the needed amount, only thing that matters in that case geometry wise will be caster, caster, ackermann and toe. Go extreme, have the car as low as you can (1mm if you can).
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Old 01-03-2017, 02:32 PM   #66
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you don't want to eliminate suspension movement...
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Old 01-03-2017, 04:45 PM   #67
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from a far discussion with friends at my club track, I can remember with a touring configuration, we are close to the point such undertray will really have effect... Again, it is quite far but I think it was useless below 75 km/h.
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Old 01-03-2017, 05:14 PM   #68
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A wind tunnel for 1/10 scale cars would be very, very, large indeed. the working section of a 1/10 scale car tunnel would be at least three feet on a side.
This wind tunnel was used to test 1/12 scale Lexan RC bodies.



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Old 01-04-2017, 06:41 AM   #69
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you don't want to eliminate suspension movement...
Almost, there's still chassis flex so any one wheel bumps won't cause much trouble. If one would retain the suspension, high spring rates, low droop and higher roll centres to keep chassis motion in check are needed.

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from a far discussion with friends at my club track, I can remember with a touring configuration, we are close to the point such undertray will really have effect... Again, it is quite far but I think it was useless below 75 km/h.
Seems too high of speed. Taking into account a 1/10th TC body has around 190cm2 of frontal area it displaces a fair amount of air at that speed.

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This wind tunnel was used to test 1/12 scale Lexan RC bodies.



Amazing! Thank you for sharing

I like this in particular:
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Old 01-04-2017, 07:13 AM   #70
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"This is what they used" That's a very, very, tiny tunnel for that body.
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Old 01-05-2017, 02:56 PM   #71
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It looks like it is, see the rapid airflow around mid cab? Nearest point to tunnel ceiling...

On the drawing board there is a Chaparral 2J inspired setup with one or two 380 powering one or two 80mm fans (go big or go home right?).
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Old 01-14-2017, 10:33 AM   #72
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Found some time today to work on the "double chassis" idea to get both: a constant working airflow underneath while still having a working suspension.
I worked out a simple solution to attach the underfloor to uncouple it from the suspension movement by putting small screws into the underside of the suspension arms near the tires. This easy and fast idea takes out around 60-70% of movement, but less than I expected. Another problem is that I have an arched rear part of the floor because of the diffuser (and how I built it). So the front effect was pretty good, but the rear effect was poor.

Now what
I guess I have to rebuild the whole floor, need to buy a heat gun and use some other tools to make a perfect flat floor. The next step would be to utilize the (steering) hubs to attach the floor to. This way should lead to a satisfying airflow and chassis movement. May the force be with me



Edit: I did some changes to the floor today to try out the double chassis configuration. The attachment to the hubs is a challenge. The available space is hardly enough. Now all works out with around half a millimeter of space between wheel and hub.



This is how it looks right now. Next week I will start building an optimized floor with less cut out area for the front and a more nice geometry.

Got my excitement back. I wonder how the car will perform outdoor at high speeds with a sealed aero channel. Let the dust fly
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Old 01-15-2017, 01:57 PM   #73
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Looks great, post more pics of the underside please.
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Old 01-16-2017, 04:19 AM   #74
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Those attachment pieces from the steering hubs to the floor, given their limited size, would probably benefit from being stronger and stiffer, like thicker lexan or carbon fiber. I really like this direction you're going, keep up the good work.

I have a few bodies I'm going to create under trays for. For scale looks only, I've got a Tamiya CLK GTR and 911 GT1. Those had flat bottoms and limited diffusers, but their construction will give me practice. I'm trying to determine which will be the best body candidate for aero experimentation. I'm looking at various Le Mans and Group C bodies.
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Old 01-16-2017, 05:07 AM   #75
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Indeed the Le Mans and Group C bodies are the best (I'm designing one for 235mm pan cars).
One very very important thing is DON'T trap air underneath, it will behave like a pillow and the car will lift. Vent it sideways (current LMP practice) or use a diffuser/rake the tray.
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