Prawn and BigAls A3 Track Car

59223A15-821E-4627-BC52-00B027C1053F_zpsbdmlsadg.jpg
 
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antwan64og said:
59223A15-821E-4627-BC52-00B027C1053F_zpsbdmlsadg.jpg
Click to expand...
:thumbs up: In one Ant!

I'm incredibly wary of putting anything flammable under the car at all. Even if stuff isn't directly adjacent to the exhaust, the radiant heat under there when we park up after a track session must easily exceed 100 degrees I'd have thought
 
desertstorm said:
You could go for some kind of horizotal splitter on the side rather than a skirt to stop air running back under the car.
Click to expand...

Good thinking Karl (I always forget, C or K?)

It's all in hand my friend :) the return lip on the side skirts will become very clear when I eventually get round to making the flat floor ;)
 
Excusing the 10 second mock I've literally just done, the skirt will sit something vaguely similar to this: (although probably not that deep)



And that's how it'll stay for a while.

When in future I do decide to experiment with some form of flat floor (if I ever find that wonder material), the return lip on the side skirts will come in very handy:



That's some way off yet though. Main vain reason for adding a skirt of sorts is to balance it out visually.
 
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Sunday morning breakfast meet :)




It was damp and overcast, which is actually a good thing when you're heading to Loomies, one of the biggest biker cafes in the south coast.
Miserable weather meant we were able to get a parking space :)






1000bhp spread over 3 cars, all running ko4's of some sort :racer:


 
More progress today on #BGWV2

When making the bracket template, I realised I'd totally forgotten about the bolt that goes through the lower mount and into the tailgate. Off the car everything assembles great, then when i offered it up with bolts, the problem became apparent!



5 minutes with the Dremel sorted that out:



At this point I got a message from a rather desperate Jardo. He couldn't get access to his workshop, and needed to use the pit and tools to hangs the engine mounts and cv joint on his golf.

Because I'm nice ( :laugh: ) I agreed and gave up my parking space for an afternoons entertainment



With Jardo underway causing chaos, I got to work on the first test fit :)

The brackets fitted brilliantly:



I bolted the wing up loosely, and positioned the feet so that everything was sat perfectly square.

First impressions of how it'll look:



I masked up the tailgate, and drew around the mounts ready to drill:



No going back now!!!



Jardo had finished his cv joint, and was on to changing his rear engine mount:



I bolted the lower feet up, and bolted the wing on for the first proper time attached to the car. I'm pleased to report that it seems remarkably solid already :) once it's all torqued up I'm confident it'll be very sturdy.



One more pic for those concerned about glass clearance:

 
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I very pleased with it so far!

It's hard to explain and get too excited, because it's nowhere near finished and currently, I'm entirely aware of the fact that it looks pretty stupid still.

I have a vision in my head of how it'll all end up though, with it all painted black, the new end plates on, and the side skirts to match and balance it all out. I think it'll look pretty cool, and more importantly, hopefully it'll all work!

It was quite interesting to see how the adjustment system would work yesterday. I've drilled the holes for the turn buckle so that with the buckle fully closed, the wing is absolutely far flatter than you'd ever want to run it, so well beyond anywhere you'd actually use it.

From 'fully flat' to 'full on vertical air brake' is amazingly only about 30mm of total adjustment on the buckle,. So I think adjustment will be measured by the individual turn
 
great work man
i cant wait to see it painted and with the ends fitted
i think it will make a huge difference to how it looks
you must be desperate for trying it out!?
also the card skirts give a surprisingly good idea of how they will turn out.
get them started me thinks!!
much respect for trying all these new things!!
 
You need some kind of testing to benchmark from?
High speed cameras on the rear struts to see what the travel is at 120mph
Or the hobo version and use cable ties to see how far they move
 
There isn't any local kids by Prawn. They have all been sucked into his turbo.
 
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Looks good nick.

antwan64og said:
You need some kind of testing to benchmark from?
High speed cameras on the rear struts to see what the travel is at 120mph
Or the hobo version and use cable ties to see how far they move
Click to expand...

Headlamp level sensors and anyway of logging resistance. Apply enough smoothing to the data and you should get a fairly good idea of the travel change, which with known spring rates can easily be transfered to a measure of force. But it's lots of effort for some numbers when I'm sure nicks are will have a good idea of whether it's working.
 
I think for now I'll just drive it and see if it wants to crash or not :laugh:

Mum and Dad came round last night, so I was keen to get the wing mounted on the car properly so we could actually head out for a test drive.

I didn't take any 'during' pics as I was rushing, but with it all bolted up, I was finally able to stand back and see what I'd created.



I was happy.

It's still far from finished, as it desperately needs new end plates, and all the brackets need powdercoating too before it can be finally fitted, but last night was the first time I got a half decent impression of how it'll look, and how stable it'll be.

Stability wise, I was really happy with how solid it felt. I had had reservations about the 6mm ali being stiff enough side to side, but the completed wing is actually very solid indeed.

Adjustment is an absolute piece of cake, taking about a minute from start to finish to crack off the lock nuts and wind the wing up or down. Dad and I set it purely by eye last night to a starting point for a test drive.



From low down behind, it looks utterly ridiculous:



And I'm fine with that :laugh:

I'll sort some new end plates asap, then when it's all in paint I can mount it up for the final time :)







Next step - side skirts.
 
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Something more like this? If you're gonna do a BGW, you may as well make it big and gay!

Wing
 
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They just look like Arm Slicers :laugh:

Probably NOT that big or silly no. just a bit less rounded, a bit more protrusion all around, but mainly beneath the wing, and more 'motorsport' esque:

NZS4337.jpg


Sport_Honda_WTCC_2014_004.jpg


Most seem to focus on projecting down below the wing rather than above. This could of course be a series limitation in something like WTCC, and Radicals and similar things also have more end plate below the wing than above.
 
well, yes, very much so! :angrymod:

We took it out for a little run last night, and I can report that initial impressions at least are pretty good.

It FEELS stiffer than I expected it to given the size of the brackets.

On the motorway at speed, there was no resonance, no vibration. With Dad watching in the mirror there was no noticeable flex or movement, and checking it over after a run it's all 100% intact and unchanged.

There was no noticeable loss of top end performance due to drag. This could of course change with the AoA, but as per out 'by eye' setup the car felt pretty neutral.

It didn't pull a wheelie, the steering didn't go light, and conversely, the back end wasn't unstable and all over the place as it's been known to be in the past.

It felt very solid and stable at speed.

That's all I can really say for now, we won't know the finer details of the high speed balance until we've had it on track, as it's impossible to reach proper 'aero' speeds on the roads responsibly.
 
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For the minute Lee no. I'd need to look into how something like that would effect air flow to the wing itself before doing anything like that.

On the Leon Supercopas they had a blanking piece instead of the OE spoiler, to keep airflow attached to the rear screen and improve flow at the wing.

That obviously won't happen on the A3 where the rear end is too steep, but I'm not sure if a small lip spoiler like the S3 would improve, or hinder the wing performance.

Hopefully when it' all coated black the brackets will blend in a lot better too!
 
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Prawn said:
Good thinking Karl (I always forget, C or K?)

It's all in hand my friend :) the return lip on the side skirts will become very clear when I eventually get round to making the flat floor ;)
Click to expand...

http://www.rapid-racer.com/aerodynamic-upgrades.php

lol, low pressure air sucking you down to the ground can only be a goof thing.

The wing look surprisingly good, I know, I mean heard stock the A3 feels a bit unstable over 130mph
 
Prawn said:
They just look like Arm Slicers :laugh:

Probably NOT that big or silly no. just a bit less rounded, a bit more protrusion all around, but mainly beneath the wing, and more 'motorsport' esque:

Most seem to focus on projecting down below the wing rather than above. This could of course be a series limitation in something like WTCC, and Radicals and similar things also have more end plate below the wing than above.
Click to expand...

More rounded = more better! Fewer straight angles gives less drag. The optimal theoretical shape for a wing is elliptical, gives the lowest induced drag. For planes they have some disadvantages with regards to stall, hence them not being used much. To reach the desired effect of reducing effective induced drag, they use 'winglets'. The end plates on your wing are really the same thing.

"Richard Whitcomb's research in the 1970s at NASA first used winglet with its modern meaning referring to near-vertical extension of the wing tips.[10] The upward angle (or cant) of the winglet, its inward or outward angle (or toe), as well as its size and shape are critical for correct performance and are unique in each application. The wingtip vortex, which rotates around from below the wing, strikes the cambered surface of the winglet, generating a force that angles inward and slightly forward, analogous to a sailboat sailing close hauled. The winglet converts some of the otherwise-wasted energy in the wingtip vortex to an apparent thrust."

This is the reason why the protrustion is on the bottom of your wing; your tip vortex is going the other way due to the camber line being upside down, when compared to an aircraft wing. Because the end plates can be seen as a separate aerofoil with its own tip vortex, the symmetrical ellipse would be an ideal shape for these. When taking into account the effects described above, it would be most beneficial to have them extend only downwards from the wing plane, preferably with a rounded corner instead of a straight one.

Hope this makes sense ;) if you'd like to discuss aerodynamics more, I'd be happy to :)
 
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well looks like Eriks designing mine then :)

suppose all you need now prawny is to actually do a track day and compare

and curby dont count!!!
 
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We'll get there Daz, don't worry.

Just a set of front discs now before it's all good to track again.
 
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