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Gordo takes over the Peter Mac Build.


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#241 Gordo

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Posted 27 July 2016 - 06:14 PM

Hi Jon, I've use 1.7mm alloy. You can see in the photos I had 10mm folds done in the sheet to add ridgity and stop vibration. There is no vibration at all. When I first ran this set up with the rear defuser. it gave more under steer . I don't think you would be able to balance the car with the rear wing I use with out a good working front spoiler or splitter.

#242 260DET

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Posted 28 July 2016 - 08:42 AM

This is about as far as anyone should go with the underside I think, start trying to seal the sides or introduce downforce shapes into the bottom and you are getting into serious aero effects that rely on certain conditions to work properly and which can suddenly change in effect due to variations in the track, wind, etc. One thing needed on the track is predictability, having to set the whole car up to suit sophisticated aero that us amateurs can only test on the track and which relies on fixed margins to work is playing with consequences that could be dangerous.

 

We know what does work and which can be fully track tested, that's as far as we should go I think. Items like wings, diffusers, splitters, Gurneys etc work and their design and effect is well enough known for us amateurs to use them as required and then adjust them as a result of track testing. As Gordo has done with the rest of his aero.


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#243 JonMortensen

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Posted 29 July 2016 - 07:05 AM

Hi Jon, I've use 1.7mm alloy. You can see in the photos I had 10mm folds done in the sheet to add ridgity and stop vibration. There is no vibration at all. When I first ran this set up with the rear defuser. it gave more under steer . I don't think you would be able to balance the car with the rear wing I use with out a good working front spoiler or splitter.

Thanks. Right now I have no rear wing, just a 250mm spoiler, and a big 150mm plywood splitter in front. Vented hood and no inner fenderwells so it should suck air out the sides. It's actually an autocross car, but once I get a few seasons behind the wheel and figure this thing out a little better I'll do track days and hopefully it will have a nice big wing by then.

 

Have mixed feelings on Richard's idea there. I agree that trying to seal the sides to the ground has risks, but I think you could run a contoured underside without the fences or big tunnels and still do better than flat bottom. Flat bottom is just something that they came up with to slow the cars down. If you look at what time attack cars are doing, some of them are running huge tunnels and going really fast. The thing that scares me about aero is trying to find the limit with whatever modification you make. I was watching an interview with a race driver and he was saying something to the effect of: "The car runs out of mechanical grip and feels like it's at the limit, but then if you just go faster the aero starts working enough to get you around the corner." I'm hoping my aero kicks in at a low enough speed that I don't have to cross that too fast for mechanical grip but too slow for aero grip threshold like he described...


Edited by JonMortensen, 29 July 2016 - 07:05 AM.

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#244 260DET

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Posted 29 July 2016 - 08:09 AM

Hi Jon, welcome to Viczcar :)

 

What I was getting at with ground hugging side skirts is that to work properly and predictably they require a stable ride height. So instead of setting our cars up just for mechanical grip we then have to start considering what suspension changes are required to suit the aero too. This requirement can include effects such as anti dive so it can get awfully complicated very quickly.

 

I have a aluminium supply book out in the shed, from memory it lists all sorts of plank type sections some of which may be useful for underbody work.



#245 d3c0y

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Posted 29 July 2016 - 09:45 AM

With the side skirts you might want to consider making them an L shape so they become vortex generators. The vortex spirals down (and "under") the side of the car preventing air leakage out the sides due to the vortex being a higher pressure than the air under the car and gives the same effect as a skirt that goes to the pavement with out any of the downsides of running a physical one. The other advantage is that smooths the airflow out over the rear wheels. 

 

Another idea for more front down force is venting the tops of the guards a la LMP1 cars:

ARX-03AStrakkaRacingSnettertonTestFebrua



#246 d3c0y

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Posted 29 July 2016 - 09:57 AM

15:40 in this video explains the what i am talking about in relation to the side skirts and has lots of stuff relevant to this discussion.

 

 

L shaped strakes at 7:50:

 

https://youtu.be/hgXni_LUgwc


Edited by d3c0y, 29 July 2016 - 10:15 AM.


#247 Gordo

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Posted 09 September 2016 - 08:21 PM

It's been awhile, but things are still happening. In my never ending search for more speed or faster lap times I'm trying a few more things. I've mounted a canard wings on each side hoping this may lessen the drag down and around the wide flared guards.
I've also cut some vents into the front guards to relive air pressure from with in the wheel arch. Also I've made a front nose extension like a G nose which will cut down the frontal area buy 8%.

#248 redrbzed

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Posted 09 September 2016 - 08:27 PM

Need pictures Gordo, hope it all goes well at PI next week.

 

Are you going to the PIARC sprint October 2nd?



#249 Gordo

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Posted 09 September 2016 - 08:32 PM

Haha, hear are some pics. The G nose add on is Top Secret. Lol.

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#250 Gordo

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Posted 09 September 2016 - 08:37 PM

I'll fit everything up this weekend. Tom Graham and I are racing next weekend at PI. Hopefully I can find some improvements .
Sinisha . Email sent.

#251 redrbzed

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Posted 09 September 2016 - 08:47 PM

Like your work, PM sent



#252 d3c0y

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Posted 09 September 2016 - 10:38 PM

Interested to see how well the fender vents work. What about cutting the back out of the flare?


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#253 Gordo

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Posted 10 September 2016 - 08:47 AM

Cutting the back out of the flare is the obvious and most logical thing. I've lined the inside of guards. 30mm clearance . Like there tubed.also the front forms part of the structural support for the flat bottom. That's why I've gone to the top of the guard. That's where the most pressure is. Have to get the air going over the car. More down force.
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#254 TomC18

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Posted 10 September 2016 - 10:37 AM

Haha, hear are some pics. The G nose add on is Top Secret. Lol.


That's because it might scare small children. Keep it hidden!

#255 Gordo

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Posted 25 September 2016 - 08:01 AM

So after last weekends sprints at PI I've drawn a few conclusions . The flat bottom doesn't seem to make any noticeable difference with the setup I'm running with. The added G nose give me a little more top end speed . But on the slower Curcuits I would not use it. The Canards on the front gards give a little better turn in. ( down force). And the rear defuser I've been running for a while now gives the back of the car stability as dose the wing. In conclusion . The main two things that make the biggest difference are the Rear Wing, and the front Splitter. After that your just trimming the car small amounts!

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#256 260DET

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Posted 25 September 2016 - 09:07 AM

It sounds like the wing mods you did were effective too Gordo.



#257 Gordo

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Posted 25 September 2016 - 05:33 PM

It sounds like the wing mods you did were effective too Gordo.


Yep. They made the most noticeable changes to how the car handled. Same on the red Zed I used to Track

#258 Gordo

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Posted 11 April 2017 - 06:56 PM

Some pics of the G-nose extension I made. When you look at the two cars Side by side there's not a lot of difference .

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#259 Cozza

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Posted 11 April 2017 - 09:50 PM

Looks great Gordo. Did you do that yourself?
Hey what wheel and tyre setup do you run? They look pretty wide.

Mick

#260 260DET

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Posted 12 April 2017 - 07:18 AM

I'm going to get in trouble here but my preference goes for the way it was. Lap times will be the decider and certainly I hope it works Gordo. Let us know. Hope to see you at Challenge Bathurst 2017.






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