Does this part of F1 suspensions move or not ?

[mertol]

Isn't this graph only showing the stiffness ratio between front and rear tires? For actual comparison between bridgestone and pirelli the test must be made with the same settings. Maybe the pirelli seem stiffer because they are less durable and the teams inflate them more to reduce the wear?

[DaveW]

Isn't this graph only showing the stiffness ratio between front and rear tires? For actual comparison between bridgestone and pirelli the test must be made with the same settings. Maybe the pirelli seem stiffer because they are less durable and the teams inflate them more to reduce the wear?

True in the first part, but individual tyre stiffness estimates can be read (each value was averaged over a full test of, perhaps, 50 runs, and different estimates represent values extracted from different teams, including GP2 for Pirelli, who were allegedly using the same tyres).

True also in the second part (though I could add at least temperature, camber, and vertical load to your list), but I don't think the plots mislead....Roughly, the Bridgestone rears would have to be inflated by an additional 10 psi to match the Pirelli rears.

[firasf1dream]

what do you mean by tyre wall ?

[beelsebob]

what do you mean by tyre wall ?

He means the vertical side of the tyre. The rubber of the tyre flexes, and this is where a lot of the vertical movement of the car comes from. Only a relatively small amount comes from the suspension moving.

[DaveW]

I assumed that Richard's first use of the phrase implied tyre deflection, as compared with (tyre + spring) deflection. On the front suspension of a 2012 F1 the ratio of tyre/spring deflection could be as high as 3.5 at the heave mode of the vehicle.

[thepowerofnone]

firasf1dream they are going off topic from what you posted, if you're interested in F1 suspension in general its a nice discussion however for the purposes of your model its irrelevant.

Having looked at your old work and paulsf1 your questions make a whole lot more sense: based on the scale of paulsf1 model (I assume yours will be similar sized) you should mount those suspension parts as fixed. Glue them in or something, because otherwise your car underfloor will always rest on the ground, unless you plan on constructing a working miniature suspension system, which would be impressive but extraordinarily difficult to achieve. Use the wishbones as load bearing elements, if I were you I would construct them running a thin piece of metal bar through them (like a thick paperclip or something similar). If you try to design them to be flexible you are going to run into so many problems.

For some perspective, I was given a die cast official Mercedes 1/24th scale model for Christmas and it uses the wishbones as fixed, load bearing structures. It has fully functional wheels and steering but even they made that simplification - I suggest you do too.

[firasf1dream]

firasf1dream they are going off topic from what you posted, if you're interested in F1 suspension in general its a nice discussion however for the purposes of your model its irrelevant.

Having looked at your old work and paulsf1 your questions make a whole lot more sense: based on the scale of paulsf1 model (I assume yours will be similar sized) you should mount those suspension parts as fixed. Glue them in or something, because otherwise your car underfloor will always rest on the ground, unless you plan on constructing a working miniature suspension system, which would be impressive but extraordinarily difficult to achieve. Use the wishbones as load bearing elements, if I were you I would construct them running a thin piece of metal bar through them (like a thick paperclip or something similar). If you try to design them to be flexible you are going to run into so many problems.

For some perspective, I was given a die cast official Mercedes 1/24th scale model for Christmas and it uses the wishbones as fixed, load bearing structures. It has fully functional wheels and steering but even they made that simplification - I suggest you do too.

exactly you're right because there is no springs ! i was thinking about making real system but it's not easy to do it so yes will do the fixed version

one more question i was thinking about the position of the upper wishbone, well it's a bit different for every team, so there is no exact place to put it from the reference plane ? because i don't remember i've read anything about it in the regulations ! correct me please if i am wrong

[thepowerofnone]

exactly you're right because there is no springs ! i was thinking about making real system but it's not easy to do it so yes will do the fixed version

one more question i was thinking about the position of the upper wishbone, well it's a bit different for every team, so there is no exact place to put it from the reference plane ? because i don't remember i've read anything about it in the regulations ! correct me please if i am wrong

The front of upper wishbone mounts to the chassis just behind the steering arm; the rear of the upper wishbone mounts a bit further back and slightly lower than the front of the upper wishbone. I don't know exactly how far back but the angle where the front and rear of the upper wishbone meet (at the front upright) will be about 30 degrees, certainly no more than that. Its advantageous to the teams to make that angle small. The rear mounting is slightly lower than the front mounting to give anti-dive handling characteristics. Its possible to figure out exactly where that point is by knowing where the vehicle CoG is but that seems a bit unnecessary for your project, its not a lot lower though. Here is a pic to show you what I mean: http://scarbsf1.files.wordpress.com/201 ... .jpg?w=300.

[firasf1dream]

aha but what did you meant by anti-dive ?
and what characteristics from that 30 degree angle ? is it because it won't support the whole system (tyre + brake + ... )if it was higher angle ?

[thepowerofnone]

aha but what did you meant by anti-dive ?
and what characteristics from that 30 degree angle ? is it because it won't support the whole system (tyre + brake + ... )if it was higher angle ?

Anti-dive is a suspension setup designed to prevent a decrease in ride height at the front and an increase in ride height at the rear of the car under breaking. Because the CoG of the car lies above the plane of the road, any acceleration in any direction (braking, accelerating, cornering) causes a moment which encourages the car to lean in a certain direction. This suspension setup attempts to prevent this.

The angle exists in the wishbones because whenever braking or accelerating in a straight line there is a force acting through the tyres in the direction of the length of the car. The wishbones exists to transmit these forces, and the cornering loads, from the tyres to the rest of the car; the push/pull rod transmits the vertical loads. This angle must exist so that the wishbones can transmit the acceleration/braking forces as a direct load acting along their length, rather than as a shear force across their length. The larger this angle is, the heavier your suspension and the worse the aero impact of the suspension will be - therefore you want to make this angle small. The development of clever carbon fibre layups allows F1 to make this angle much smaller than the equivalent steel suspension, certainly if you two components had the same mass, which is why on the photo you posted the angle is maybe 50 degrees, but if you look at photos of f1 suspension its maybe 25 degrees.

[firasf1dream]

so you mean if the angle is high, the force that will make the suspensions take the load will be higher but if it is low it will make it easy and not break ?
i am having a bit of problems understanding what you mean because english is not my native language nevertheless my english is good but when it comes to technical stuff it's hard to get the idea easily :S

[thepowerofnone]

Ok so there are two "bars" on the top wishbone, they are mounted far apart on the chassis but they meet up by the wheel. The angle they form there is what I'm referring to. If that angle is small, then the braking and accelerating forces must largely be transmitted by shear loads; if that angle is large then the braking and accelerating forces are largely transmitted by direct loads. Shear failure loads are often much lower than direct failure loads, and they tend to have greater stress concentrations too. Therefore shear loads are undesirable - we want to transmit our loads as direct loads.

However, to transmit our loads as direct loads we must make this angle large. If we do that, the wishbone arms must be made longer (which increases weight) and the two upper wishbone arms are further away from each other which is bad for aerodynamics. Therefore we make this angle as small as we can without causing failure. We can do this much more efficiently in f1 because we use carbon fibre suspension, which is a highly anisotropic (non-uniform) material, so we can lay it in a particular way to best resist shear forces.

[firasf1dream]

Ok so there are two "bars" on the top wishbone, they are mounted far apart on the chassis but they meet up by the wheel. The angle they form there is what I'm referring to. If that angle is small, then the braking and accelerating forces must largely be transmitted by shear loads; if that angle is large then the braking and accelerating forces are largely transmitted by direct loads. Shear failure loads are often much lower than direct failure loads, and they tend to have greater stress concentrations too. Therefore shear loads are undesirable - we want to transmit our loads as direct loads.

However, to transmit our loads as direct loads we must make this angle large. If we do that, the wishbone arms must be made longer (which increases weight) and the two upper wishbone arms are further away from each other which is bad for aerodynamics. Therefore we make this angle as small as we can without causing failure. We can do this much more efficiently in f1 because we use carbon fibre suspension, which is a highly anisotropic (non-uniform) material, so we can lay it in a particular way to best resist shear forces.

ok i had to translate some technical words to french which is the language i studied these stuff with, "shear load" is "charge de cisaillement" ok this one i got it but "direct load" mmm i guess you meant like the passive suspension when it takes the load directly ?
about the carbon fiber yes i understood i took the composite course last year
ok the weight thing makes sense, the aero mm i guess it's making an opposition to the air that has to enter the sidepods ? because about it's shape it's already made in a way that has less drag

[thepowerofnone]

direct load = {sigma}
shear load = {tau}

[firasf1dream]

direct load = {sigma}
shear load = {tau}

yes ok that's it so direct is traction or compression