Tech Spam thread - because 1/4" BSP gets 5 hand spans to the jiggawatt

[SOHC]

Do you need one?  i can grab a few for you.

 

Yes please

[Roman]

Before you go balls deep and wire up sensors etc there are special paints you can apply to the disc and it will change colour when you reach that temperature. I am not sure where you source it but we used to have three different patches (600 700 800 degree C or whatever) on the disc and you can quickly see where the temp got to.

I'm pretty keen to wire up sensors either way, for interests sake.

 

Ferodos have been good in terms of braking feel / no fade / etc but yeah, its the wear rate thats the killer currently.

 

Ahhh well at least my discs arent wearing by any significant amount so far. I'll try a different type of pad next time.

[Roman]

(Disclaimer: Below rambling is for sake of interest, not necessarily that I need extra airflow to brakes at this stage)

Last night I drew a fairly accurate model of one of my front wheels, the hub, and the disc, and a big slab of "ground"

 

No caliper or suspension yet but just for interests sake looking at the basics of how air flows around the disc / spokes / etc when its rotating.

 

It seems that when the wheel is travelling forwards at 120kph, (and rotating...) There's virtually zero air flow through the centre of the wheel or near the disc.

 

The tire builds a big wake that seperates at the leading edge of the tire and thats the last airspeed that the wheel or disc pretty much ever sees.

 

Even with a crude representation of the front of the car covering upper half of the front of the wheel. The flow around the wheel only changes things ever so slightly because it's the high pressure zone down low under the front of tire which intiates the wake that then spills upwards.
 

I was sort of expecting the spokes of the wheel to be stirring up some air in a semi meaningful sort of way, but doesnt look like it acheives anything useful.

What's interesting to see is that without supporting aero mods ahead of the wheel. Aerodynamic wheel covers, despite looking sleek likely acheive next to nothing as there's no air speed going past them. Which is probably why they were last seen in the 80s.
Even if they stuck out by say 40-50mm it wouldnt make any difference currently.

 

I can now see the rationale behind "speed flaps" ahead of the tire mounted to the lower gaurd.
Which are there to disrupt airflow before it gets to the tire, so it flows more uniformly around it.

I'm not taking the above results as gospel but it was certainly a lot different to how I imagined flow in and around a wheel would work. Will post some pictures later so this rambling makes more sense.

[Nominal]

There is some commentary here on wheel deflectors

 

http://www.autospeed.com/cms/article.html?&title=Modifying-UnderCar-Airflow-Part-2&A=113182

[Roman]

Julian Edgar is the man.

Read one of his books back in the day, first time I'd seen anyone try to quantify changes for anything to do with modifying cars.

[Roman]

Looking in plan view over a wheel

 

 

Isosurfaces are my new favourite gimmick. really need to see the 3D model and rotate it to get an idea of shape though.

 

Basically it draws a 3D mesh of where the flow is at a certain speed or pressure or whatever. So this is wheel going 120kph but showing where the flow drops to 90kph or below. Which is pretty much as per the picture above.

 

 

[kyteler]

Whilst I find that awesome. Isn't it irrelevant without the rest of the surrounding vehicle?

[Roman]

Absolutely!

A very crude approximation of the wheel well etc is in the model, I've just hidden it for sake of pics.
 

[kyteler]

Please generate a 3D model of the 110 that is my avatar and tell me whether I would be wasting my time with that kit/totally irrelevant, I'm just curious as to how the air would react.

[flyingbrick]

Does the disk itself move much air at 120kph? Obviously they are vented and designed to sortof throw air outward

[Roman]

So little air that it's truly negligible compared to what else is going on around the wheel.

 

(in the example of this particular disc etc at least)

[Spencer]

Aero shit is so cool. Used to foam on the aero articles in some magazines back in the day. They would make brake ducts, wings etc then backyard test with data logging and a big fan + smoke.

[Spencer]

Makes you appreciate sports cars where if all the factory shit is in place have lots of the air movement stuff sorted out.

[flyingbrick]

Aero shit is so cool. Used to foam on the aero articles in some magazines back in the day. They would make brake ducts, wings etc then backyard test with data logging and a big fan + smoke.

It's also amazeballs that much of the testing with smoke and string can be tested virtually by the DIYer now..

David did a 3d thing of a ute to show airflow going over the deck. Was exactly what mythbusters found during one of their studies.... only David didn't have to construct a physical model and flow water over it in a special fish tank.. SO COOL

[tortron]

so much possibilites now

 

make sure you record results

change one thing at a time

[sentra]

what is your feelings on the brabham fan car dave?

[Roman]

Pretty much anything in F1 that gets banned, is usually awesome haha.
The fan car was cool but I'd say a modern F1 car would make way more downforce anyway. 
Although its a bit of a laugh that the fan car pretty much looks like a big rectangle box, compared to having a zillion ugly winglets diverting every little tuft of air.

[chris r]

Re charge piping. Turbo - coooler-tb how much less/difference will a section of 2" flow compared to 2.5?

[Rookie]

Fan car makes oodles more down force than a modern f1 car, probably even one from the aero era, and has no parasitic drag from turning moving air into df. Basically they killed a super legit idea.

[Roman]

Yeah true, I guess it wasnt speed dependent to generate downforce either which is cool.

The problem with the fan car though, and any aero car / ground effects I guess.

 

Is that as soon as you clip over a ripple strip or something else that breaks the seal with the ground. You go from having 100mph worth of grip down to 40mph worth of grip (or whatever)

Which was likely a death sentence in that era.

 

Although I doubt this was the rationale behind banning it, didnt seem like many fucks were given about race car drivers safety in that sort of era!