*Aerodynamic maths channels*

[sonic_87]

Hi,
we are looking for a channel in Pi toolbox that will allow us to determine 'downforce' on a front wing during a straight line test.

We have thought we will use the pushrod loads on all four wheels as a measure for displacement then will:
1.subtract 'total static load' = 0 load
2.weight transfer will be (-) under acceleration this will comeoff
3.if the weight transfer is known the remaining load must be downforce

If this is making sensse to anyone, just wondered if there was a way to split this aeroforce up into drag and lift so the actual downforce is known, this maybe too technical, but hay
if anyone has any advice would be appreciated, thanks

[EfiOz]

You're entirely correct in your assumptions. The load can be calculated by damper movement with relation to spring rate and motion ratio.

[Félix]

I have heard of coastdown tests as cheap replacement/confirmation for wind tunnel testing. The way I understand it, you can infer downforce from suspension load/travel sensors and I guess drag from the speed at which a car decelerates when power is cut or the power needed to maintain a given speed. That must include a lot of trial and error as well as figuring out what effects other constants have, but I guess it can be efficient and it must be quite fun for the team in charge.

[greenamex2]

I can see it working for changes once a baseline has been established, assuming all other environmental factors such as wind direction and strength and surface gradient are similar.

I tried to work out in-gear acceleration for any given road speed/gear, the Toolbox formula worked but the numbers at Oulton were all over the place due to gradient. Waiting for a flatter circuit.

Must get some damper position sensors fitted when funds allow, sounds fun.

[EfiOz]

You don't need to do coast down tests to get meaningful numbers. It can be done from normal race data. One word of caution, you really need to have a good handle on pitch and roll centres otherwise the load transfer numbers skew it pretty bad.

More reading
http://www.dataanddynamics.com/index...lysis&Itemid=2