Isn't air everywhere? Aerodynamic forces are the result of the quantity of matter(air) over in and around the car, downforce is measured in Nm,
Downforce is measured in N.
Nm would be a torque, or a bending moment. Something with a lever arm application.
Isn't a car on wheels a lever with 2 compliant fulcrums?
In terms of downforce, the thing being measured, it doesn't matter what the car is considered to be. The unit for downforce is N.
One could argue that a car is a beam with cantilevered ends and a simply supported centre section. But the force being applied to it would still be measured in Newtons.
If you are more fortunate than others, build a larger table not a taller fence.
Isn't air everywhere? Aerodynamic forces are the result of the quantity of matter(air) over in and around the car, downforce is measured in Nm, just like the wheel rate. I had to raise the spring rate and have my shocks revalved to handle the aero forces on my little home made kit. Even then I was still riding the rear bumpstops on the back straight. Hell, I had to get a bracket welded to the chassis to keep the upper control arms from getting pried off due to the extra forces.
Did your car get worse on the brakes due to increased weight with all the added downforce?
Downforce does give an apparent increase in weight without the usually required mass increase. Which is why it's so good for going around corners, of course.
Isn't air everywhere? Aerodynamic forces are the result of the quantity of matter(air) over in and around the car, downforce is measured in Nm, just like the wheel rate. I had to raise the spring rate and have my shocks revalved to handle the aero forces on my little home made kit. Even then I was still riding the rear bumpstops on the back straight. Hell, I had to get a bracket welded to the chassis to keep the upper control arms from getting pried off due to the extra forces.
Did your car get worse on the brakes due to increased weight with all the added downforce?
Downforce does give an apparent increase in weight without the usually required mass increase. Which is why it's so good for going around corners, of course.
Yes, but that's not what I was pointing at
Yes! I was using stock calipers, I was limited by the braking force of the single piston calipers. I could certainly use bigger brakes but I don't want to sink another $6,000 on a BBK just yet.
At 3:04 it seems there are many vanes at front part of undertray.
Any better picutre and function of it?
Why so many vanes, dont they block/slow down airflow too much?
On one side they raise pressure, on the other side they lower pressure. The vanes act like a passive air pump. The low pressure zone behind the vanes acts as a vacuum cleaner for air upstream, accelerating it.
Remember that flow velocity is dependent on the pressure difference between the inlet and throat of a venturi channel. The greater the pressure difference between the inlet and throat the greater the flow velocity. Like an air compressor, the pressure in the air lines is ~6x the pressure at ambient, so the air rushes out of the lines into ambient.
The strakes create high pressure, by the 3rd law, there's an equal but opposite reaction elsewhere.
Wings work the same way no? One side raises pressure, and the other side lowers pressure. Mass is displaced and force is generated.
How did the fan car work? It maintained low pressure underneath, which allowed the high surrounding static pressure to press down on the car. The skirts were used because air pressure functions in all directions. That fan creates high pressure on one side(the blowing side) and low pressure on the other.
The strakes at the front are basically static fans, they push air outward instead of letting it go rearward, less airmass means less air pressure. Less air pressure means more acceleration of upstream air, more momentum, means less static pressure(up to a point).
The strakes are what choke, because that channel is so small, you can see on pressure traces, there's a pressure peak where the innermost strake and the floor interact. That pressure peak indicates sonic choking. From there the only way to further accelerate the air is to lower the backpressure downstream.
Look closely, you see the pressure at the leading edge of the floor between the inner strake and the plank area have slightly high pressure, then the airflow starts accelerating despite a diverging section. When airflow accelerates in a diverging section, it implies the flow velocity is high enough for compressibility effects to be at play, or that the flow is choked/sonic.
You notice the inner strake diverges from the floor on the RB18. With non compressible flows, diverging sections reduce airflow velocity, yet from the CFD we see that the airflow clearly accelerates.
Those outer fences are a double edged sword, if you make them nice and outwashy they can push the front wheel wake outward, but on the other hand, they can starve the floor of airflow under yaw.
Yes! I was using stock calipers, I was limited by the braking force of the single piston calipers. I could certainly use bigger brakes but I don't want to sink another $6,000 on a BBK just yet.
Wow, I can only imagine how poor the cornering is, with all the extra downforce weight...
Yes! I was using stock calipers, I was limited by the braking force of the single piston calipers. I could certainly use bigger brakes but I don't want to sink another $6,000 on a BBK just yet.
Wow, I can only imagine how poor the cornering is, with all the extra downforce weight...
I could use more power, I'm pretty much flat through turn 1, while weight is increased inertia is not, or at least not at the same rate, I imagine aero yaw forces could work to increase or decrease inertia of the vehicle. Like if you have really long wide endplates on your front splitter that create strong aero forces it could make turn in sluggish at speed, because you have to overcome the side-thrust from the endplate.
I could use more power, I'm pretty much flat through turn 1, while weight is increased inertia is not, or at least not at the same rate, I imagine aero yaw forces could work to increase or decrease inertia of the vehicle. Like if you have really long wide endplates on your front splitter that create strong aero forces it could make turn in sluggish at speed, because you have to overcome the side-thrust from the endplate.
Could you share some photos of the car? Maybe there is a thread for personal projects or something like that
I could use more power, I'm pretty much flat through turn 1, while weight is increased inertia is not, or at least not at the same rate, I imagine aero yaw forces could work to increase or decrease inertia of the vehicle. Like if you have really long wide endplates on your front splitter that create strong aero forces it could make turn in sluggish at speed, because you have to overcome the side-thrust from the endplate.
Could you share some photos of the car? Maybe there is a thread for personal projects or something like that
If inertia of the car is not increased with downforce (ie just mass in this case, ie weight) meaning the braking force doesn't have to deal with more mass to produce the same deceleration and should be better with increased drag (which inevitably comes with aero package), why is the braking worse? Could the aero balance be too much on the rear axle, unloading the front and decreasing front tyre traction - leading to poor braking performance?
I could use more power, I'm pretty much flat through turn 1
If you are flat out, ie power limited, what is causing it? Could it be drag?
How come increased weight with downforce doesn't push you out of the corner? Is it maybe not an increase in weight, but rather an increase in vertical load? (weight is a type of vertical load, but not every vertical load is (a) weight)
I imagine aero yaw forces could work to increase or decrease inertia of the vehicle
How can any external force change the inertia of the car, ie change its mass, center of mass and/or mass distribution? (parts flying of the car is not what I'm pointing at)
If the inertia doesn't actually change, could the aerodynamic side forces influence the behaviour, ie car dynamics?
The strakes at the front are basically static fans, they push air outward instead of letting it go rearward, less airmass means less air pressure. Less air pressure means more acceleration of upstream air, more momentum, means less static pressure(up to a point).
Dont agree with this logic, if you want less airmass than you can simply put plate to the ground at front bumper and stop airflow completly.
Idea is to increase airflow under car not decrease.
Maybe they use vanes to produce vortices to seal side of flor, because they cant use skirts that touch road...
