When will they test the theoretical downforce of an F1 car upside-down?

[Markus Neumann]

In all fairness: Just because an F1 car produces more downforce than its own weight doesn't necessarily mean it will produce an equal amount of lift when turned upside down.
For one thing, I kind of doubt the blown diffuser would work as planned, given how perfectly calibrated the exhaust gases need to be.
Additionally, you would probably have to revisit the fuel tank, cooling, etc - everything that contains fluids. So I doubt you could just take a regular F1 car and run it up-side down, you'd have to make some adjustments first.

Nevertheless, the laws of physics obviously dictate this this can work if done correctly. F1 cars are basically inverted airplanes, so if you invert an F1 car you get...

 

[Hampus Andersson]

In all fairness: Just because an F1 car produces more downforce than its own weight doesn't necessarily mean it will produce an equal amount of lift when turned upside down.

It will because the roof is now the floor remember, it generates downforce that sticks it on the surface.
For example the floor, it´s sucking itself down to the roof not because of lift but downforce.
It´s just that it first of all needs to overcome gravity, then what´s left is used for pushing the tires into the roof.

So 600kg car, needs 600kg of downforce to just break even.
Then what´s left is what sucks the car to the roof.

For one thing, I kind of doubt the blown diffuser would work as planned, given how perfectly calibrated the exhaust gases need to be.

Don´t need it, you can do the same with a 2014 car if you wanted.

Nevertheless, the laws of physics obviously dictate this this can work if done correctly. F1 cars are basically inverted airplanes, so if you invert an F1 car you get...

Invert the wings and you get an aircraft, tip the car upside down and it´s still generating downforce.

 

[Markus Neumann]

It will because the roof is now the floor remember, it generates downforce that sticks it on the surface.
For example the floor, it´s sucking itself down to the roof not because of lift but downforce.
It´s just that it first of all needs to overcome gravity, then what´s left is used for pushing the tires into the roof.

So 600kg car, needs 600kg of downforce to just break even.
Then what´s left is what sucks the car to the roof.


Don´t need it, you can do the same with a 2014 car if you wanted.


Invert the wings and you get an aircraft, tip the car upside down and it´s still generating downforce.

I understand the principle, no need to explain. And yes, I know that the cars have enough downforce even without a blown diffuser. However, about your last point: You mean that if the car ran upside down, the force pushing it to the ceiling would still be called downforce and not lift? Because that seems kind of counter-intuitive.

 

[Markus Neumann]

Is it not possible to edit posts anymore or am I just blind?

Anyway, I checked myself now. I always thought downforce and lift are just opposing forces, and while that may be right in principle, downforce is actually just a special case of lift when it works in a downward trajectory.

But this means that the force pushing the car to the ceiling would be called lift, wouldn't it?

 

[Element515]

I wouldn't call it lift, because it's still pressing the car to a surface. And I'm pretty sure it's been said that F1 cars can stick themselves theoretically upside down lower than 100mph.

The only problem to doing this in real life, is the fact oil and gas tanks wouldn't work very well upside down. You could do a flip around the top of a tunnel. But, that's not impressive. Top gear has done that in a little fiat or something in the tunnels under england.

 

[Miguel Gonzalez]

Is it not possible to edit posts anymore or am I just blind?

Anyway, I checked myself now. I always thought downforce and lift are just opposing forces, and while that may be right in principle, downforce is actually just a special case of lift when it works in a downward trajectory.

But this means that the force pushing the car to the ceiling would be called lift, wouldn't it?

The two opposing forces are Weight and Lift when dealing with airfoils. "downforce" is subjective to where you percieve the ground to be. For example if you had a circular tube track that a car could accelerate and drive updide down, the car's downforce will hold it to whatever surface is below the car regardless of its orientation.

Another way to think about it is Downforce is inverted lift. When low pressure air flows over an air foil the resultant pressure below causes it to lift up, if you flip the airfoil upside down so that the low pressure is on the bottom the resulting high pressure above will force the object down.

I wouldn't call it lift, because it's still pressing the car to a surface. And I'm pretty sure it's been said that F1 cars can stick themselves theoretically upside down lower than 100mph.

The only problem to doing this in real life, is the fact oil and gas tanks wouldn't work very well upside down. You could do a flip around the top of a tunnel. But, that's not impressive. Top gear has done that in a little fiat or something in the tunnels under england.

The cars would have to be retrofited with positive displacement pumps for all of its systems if it runs the possibility of inversion so that even without the force of gravity all the components would still have positive pressure.

 

[Element515]

The cars would have to be retrofited with positive displacement pumps for all of its systems if it runs the possibility of inversion so that even without the force of gravity all the components would still have positive pressure.

Yup, exactly. And you need to find a really nice tunnel where someone is willing to risk damage to a multi million dollar car.

 

[Hampus Andersson]

I understand the principle, no need to explain. And yes, I know that the cars have enough downforce even without a blown diffuser. However, about your last point: You mean that if the car ran upside down, the force pushing it to the ceiling would still be called downforce and not lift? Because that seems kind of counter-intuitive.

You have to keep in mind that the roof is now the floor, downforce does not mean down to earth, it´s simply a downward thrust pushing the car into the ground and in this case the ground is the roof.

The car will be generating downforce all the way through from the regular ground, through the ramp and then stick to the roof.

I know it sounds very weird but the downforce as i said does not mean "pushing the car down to earth" it simply means pushing the car into whatever ground you have.

If you just invert the wings then you have an aircraft.

 

[Hampus Andersson]

Another example is an aircraft. Generating lift with it´s wings.
If you are up in the air then turn the plane upside down you are still generating lift from the wings. Just that it´s the wrong direction.
Only if you keep the frame right side up and invert the wings do you really create downforce.

 

[Markus Neumann]

Another example is an aircraft. Generating lift with it´s wings.
If you are up in the air then turn the plane upside down you are still generating lift from the wings. Just that it´s the wrong direction.
Only if you keep the frame right side up and invert the wings do you really create downforce.

An aircraft is exactly what I thought of. If you turn an F1 car upside down its wings have a similar AoA as an aircraft.

Like this:

I know that Wikipedia isn't the best source, but I couldn't find anything more reliable and there it says:

While the common meaning of the word "lift" assumes that lift opposes gravity, lift in its technical sense can be in any direction since it is defined with respect to the direction of flow rather than to the direction of gravity. When an aircraft is flying straight and level (cruise) most of the lift opposes gravity. However, when an aircraft is climbing, descending, or banking in a turn the lift is tilted with respect to the vertical. Lift may also be entirely downwards in some aerobatic manoeuvres, or on the wing on a racing car. In this last case, the term downforce is often used.

I understand that in the way that the term downforce is only used when lift works in the same direction as gravity.

I'm not even saying you're wrong. I'm just not convinced so far. Do you have any reliable source for what you said?

 

[Hampus Andersson]

Your quote sums it up nicely.

"Lift may also be entirely downwards in some aerobatic manoeuvres"

Just like Downforce upside down in a tunnel is still downforce.
You see downforce has nothing to do with the earth itself. It´s only the effect on the car.
So the only way you can say the car is generating lift is by inverting the wings, not the car.
By simply inverting the car it will produce downforce.
Just like the quote says about airplanes, even though it´s upside down in aerobic maneuvers it´s still generating lift.

I understand it´s confusing, i spent some time yesterday thinking about it and your quote simply confirms it.
Lift/Downforce is not related to your position on earth. It´s only an effect on the car/plane.

Best way i can describe the difference is running on a wall. It´s downforce that will push the car into the wall horizontally.

 

[Markus Neumann]

Your quote sums it up nicely.

Yes, I know, it can also be understood that way

 

[Hampus Andersson]

Yes, I know, it can also be understood that way

It all has to do with inverting the wings or the vehicle itself.

If you take an airplane and fly it upside down, it´s still generating lift.
If you take the same airplane and invert the wings it will generate downforce inhibiting it from leaving the ground.

I can´t explain it any further but the wall thing is the best way to explain why it´s downforce rather then lift that is being created.

 

[Markus Neumann]

I can´t explain it any further but the wall thing is the best way to explain why it´s downforce rather then lift that is being created.

I fully understand your argument, it's just that I rarely believe something without a reliable source Oh well, guess I'll have to do without one on this one.

 

[Hampus Andersson]

I thought your own quote summed it up brilliantly.

Downforce and drag are the same in reality but from the cars point of view it´s always experiencing downforce.
The car doesn´t care which way is up.

Downforce is a downwards thrust created by the aerodynamic characteristics of a car. The purpose of downforce is to allow a car to travel faster through a corner by increasing the vertical force on the tires, thus creating more grip.

Lift decreasing the vertical force on the tires.

 

[Markus Neumann]

I just found an interesting post on the topic as a whole (not the downforce vs. lift matter):

JButton said that a F1 car weighs about 650kg and generates about 2000kg of downforce. The max speed of an F1 car is limited by aerodynamic drag to about 330kph.

Consider an F1 car going 330kph and generating 2000kg of downforce. Right side up the force perpendicular to the tires is 650kg, the weight of the car, plus 2000kg downforce for a total of 2650kg. If this car is upside down on the ceiling of a tunnel then the 650kg weight of the car is no longer pushing the tires onto the road (ceiling). Further the 650kg weight of the car is now pulling the tires away from the road (ceiling). So the tires are pushed against the road (ceiling) with a force of 2000kg - 2 * 650kg = 700kg. Forward thrust provided by the tires is proportional to the perpendicular load so the drop in perpendicular load from 2650kg to 700kg reduces the car's ability to oppose aerodynamic drag by almost 75%. Since at 330kph the propulsive force of the tires exactly balances the aerodynamic drag, reducing the propulsive force by 75% means the car cannot maintain the same forward velocity. The car must slow down or spin the tires which will also cause it to slow down. Aerodynamic braking at 330kph generates about 4Gs, so it will slow down very quickly.

As the car slows down the downforce will decrease as will the drag. Since downforce proportional the square of the speed, the downforce will drop even faster than the forward speed. As the downforce drops the force perpendicular to the road also drops and so the force opposing drag drops and the car slows more. At somewhere in the neighborhood of 160kph the downforce will will fall below 650kg while the drag will still be substantial. At that point the car will fall off the ceiling.

So could an F1 car drive on the ceiling? Very briefly. If the car was driven forward up a curved wall onto the ceiling at maximum speed, it would remain on the ceiling for a short distance, maybe 50m, before slowing so much that it fell off. The G force of driving the car up the curved wall at that speed would likely destroy the car. Trying to drive down a circular tunnel and moving diagonally up the wall would most likely fail as the drag would slow the car excessively before it ever got onto the ceiling. Much as it is a very cool notion, in practice an F1 car could not drive on the ceiling of a tunnel.

Editing myself: "So the tires are pushed against the road (ceiling) with a force of 2000kg - 2 * 650kg = 700kg."

Not quite. Should be 2650 -(2*650) = 1350kg. Doesn't change the analysis much. The end result is that the car doesn't slow down quite as quickly. So maybe it can drive 51m on the ceiling before falling off.

The poster is anonymous, but at least it makes a lot of sense to me. Source: http://www.newscientist.com/blog/lastword/2009/05/aerial-glue.html

 

[Jordi Casademunt]

Lift doesn't neccesarily mean the force goes upwards, according to Wikipedia:

A fluid flowing past the surface of a body exerts surface force on it. Lift is the component of this force that is perpendicular to the oncoming flow direction.

While the common meaning of the word "lift" assumes that lift opposes gravity, lift in its technical sense can be in any direction since it is defined with respect to the direction of flow rather than to the direction of gravity.

So basically, as long as there's a force perpendicular to the movement direction (upwards or downwards) caused by interactions with the fluid (air, water, whatever) it's lift.

A F1 car creates a lift force, downwards. I suppose the term downforce is used just so there isn't any confusion between the physics term lift, and the common meaning of lift.

So basically, the airplane always creates lift. The F1 car always creates lift. The lift created by a racing car is also called downforce. At least that's what I understood.

 

[Hampus Andersson]

(to Markus, got ninjad)

Good post, also note he says downforce even though the car is upside down in a tunnel.

So basically, the airplane always creates lift. The F1 car always creates lift. The lift created by a racing car is also called downforce. At least that's what I understood.

Exactly. Basically lift and downforce are two sides of the same coin to make it even more simple.

 

[Rupe Wilson]

Remember ground effect.. the famous fan car.. this was also interesting.
http://en.wikipedia.org/wiki/Ground_effect_(cars)

 

[Markus Neumann]

An article in an actual scientific journal which shows the math:
https://physics.le.ac.uk/journals/index.php/pst/article/view/262/127

They say it should be possible, however they a) do not take the concerns into account which I quoted above and b) point to another problem:

The radius of curvature would also have to be taken into account; as if this is too small then too much air would go underneath the car and hinder the aerodynamics of the car