2021 Italian Grand Prix - Monza, Sep 10 - 12

[i70q7m7ghw]

There is a definitely a benefit to a multiple slipstream up to a point, I don't know why you are trying to argue the opposite. Look at bicycle racing, where aerodynamic drag is 80-90% of power consumption. You can find papers easily showing the reduction in drag from drafting two or three other riders instead of just one.

From: http://iawe.org/Proceedings/EACWE2013/B.Blocken.pdf (not a peer-reviewed article but you get the idea)
https://cdn.shopify.com/s/files/1/1414/ ... 1504656336
https://i.imgur.com/4X6HJxL.png

Of course F1 cars following at 100m distance is not the same as cyclists following at 100mm distance, but you get the get the idea at least!

No words. Just no. There is no "pulling" effect.

It's called a tow because it's a metaphor, it's not literal.

In other news, water is wet! What you say is understood. In seems like a "tow" because this is a powered vehicle, and with less resistance it accelerates faster for the same amount of power.

Cycling is totally different. The effect of two cars versus one in F1 is negligible, and is certainly not enough to be noteworthy or even called a "double" tow.

[JordanMugen]

Cycling is totally different. The effect of two cars versus one in F1 is negligible, and is certainly not enough to be noteworthy or even called a "double" tow.

Source?

At the very least it means the team's second driver is not totally without a slipstream.

[Hoffman900]

The NASCAR and Indy guys have understood the benefit of multiple car drafting for half a century now. Cyclists for even longer.

This is actually where most of the aero development work in NASCAR is focused. I know there are some former F1 aero guys in their ranks and they discuss how hard of a problem it is. Not that it is any harder than F1, just that their focus is the effects of aero when accounting for side drafting, multiple cars in front, cars behind, etc. and it presents a whole new set of challenges / problems to solve. Then there are the dynamics of running close to a wall.

https://www.motorsportmagazine.com/arti ... ical-heels

[i70q7m7ghw]

Cycling is totally different. The effect of two cars versus one in F1 is negligible, and is certainly not enough to be noteworthy or even called a "double" tow.

Source?

At the very least it means the team's second driver is not totally without a slipstream.

Yeah I mean that's a different point entirely and I already said the biggest benefit is the two drivers behind the first BOTH get a boost i.e. Perez was also getting a tow.

[Just_a_fan]

Again, it may work like that in computer games, but in real life it's not the case, particularly in F1 with the amount of turbulent air. The car ahead creates a drag reduction by creating an area of negative pressure, the fact there are two cars does not mean there is an additional effect.

There is no "negative pressure". There is pressure and there is less or more pressure. Once you get to zero pressure, that's it. Negative pressure doesn't exist (in the macroscopic world in which race cars work, anyway).

Tow is not about pressure, it's about resultant air flow direction. A car travels through still air. The air interacts with the car's surfaces and is deflected in various ways. The car pulls the air with it - that is what results in a resultant reduction in air speed felt by the following car. Drag is proportional to the square of the velocity. By dragging some of the air forward with it, the lead car reduces the effective air velocity of the following car. Thus the drag of the following car is reduced.

This effect is nicely demonstrated by the effect that wind has on the cars - a headwind in to a corner allows later braking. A tail wind requires earlier braking. Why? Because the head wind means more downforce, the tail wind means less downforce. Why? Because downforce changes with the square of velocity. A head wind increases the velocity, a tail wind reduces the velocity. A 40% change in air velocity gives a doubling / halving of downforce and drag.

Power absorbed by drag increases with the cube of air velocity. So a small reduction in velocity - such as caused by a car ahead dragging air with it - reduces the power required to overcome the drag. And so the car's speed can increase until the drag absorbs the power again.

Two cars will pull the air with them to a greater degree than will one car. Hence two cars can increase the tow effect on the third car because it experiences a more reduced effective air velocity than the second car.

No words. Just no. There is no "pulling" effect.

It's called a tow because it's a metaphor, it's not literal.

Yes, there is. It's not "negative pressure" because, quite simply, that's impossible.

Want to know what a car does to the air? Stand next to a fast road and feel what the air does as a car goes by. Which direction does the air move after the car has gone by? Stand there when the road has a number of cars driving quickly along it. Which direction is the air moving? And is it moving faster, slower or the same speed as the single car? Come back when you have the answer.

[PlatinumZealot]

There is negative pressure in a sense. Pressure a scalar but pressure force is a vector.
But I get what you mean.

[Just_a_fan]

There is negative pressure in a sense. Pressure a scalar but pressure force is a vector.
But I get what you mean.

There is no negative pressure. Pressure is zero or greater.

You can have a pressure difference, of course, where one pressure is lower/higher than another pressure. But that's not negative pressure.

[casper]

Negative pressure is vacuum. I always watch my negative pressure value not to exceed a certain limit during vacuum distillation or else it will overcook what I am drying. But in the context of this discussin re: racing car aero, negative pressure is non existent.

[Hoffman900]

Here is what the Indy Car engineers do in terms of modeling drafting / overtaking in CFD:
https://www.nextplatform.com/2018/11/20 ... long-haul/



Obviously validating this would be tough, so I'm not sure the limitations of their models. To do this properly would likely require more computing power than Boeing has.

[zibby43]

No one cares that RBR sacrificed Perez (again) for Max.

So when Merc tell Bottas to pull over for Hamilton tomorrow so he can get 3 points (since BOT is starting at the back anyway), there is not going to be a peep about it.

Right?

I care. I think it was very unsporting. Red Bull should have waited it out to wait for some other sucker to go first on the final Q3 run! (With amusement ensuring ala 2020 or 2019, whenever the mess was when no one wanted to go first.)

Most unreasonable for Perez to be expected to tow Verstappen. Better off to go with the pack, and let somebody else make the call to lead out.

I tip my cap to your honesty.

I was more just trying to point out the double standard in media (and on social media) with how differently the situations are perceived, despite the fact that RBR are significantly more overt in their efforts to relegate Perez to Max’s valet.

[Rodak]

Unfortunately Perez has not been close enough to Verstappen to make the comparison to Hamilton and Bottas. Why not use Perez as an aid until he shows comparable speed to Verstappen? Perez is totally out of the Driver's Championship and as a team mate should help Verstappen if he can. If you were team manager of Red Bull how would you handle Perez/Verstappen? I'd totally support the driver who might win the championship.

There are two championships, the driver's and the manufacturer's; Mercedes is really pulling away in the manufacturer's with high points finishes for Bottas and also ran for Perez. I think #2 Perez is a good driver, but his qualifying spots are just not on the level of #2 Bottas. It's tough, but only one driver can win the championship and that is between Max and Lewis.

[SmallSoldier]

If a car gives a tow to the car behind it, and that car gives a tow to the car behind it, the car at the back gets the benefit of both tows.

A tow improves top speed (until you run out of gearing, of course). Driver A tows Driver B. Driver B is quicker than he would otherwise be. Driver C, if he is in the correct position, can gain a tow from Driver B. His own top speed will increase unless he hits the gearing/rev limits. Driver C's tow isn't as big as Driver B's, of course, but he will gain more than he would have if he'd only been behind one car. Obviously, if Driver B runs in to the rev limit, he can't gain and Driver C will also likely hit his limiter.

Again, it may work like that in computer games, but in real life it's not the case, particularly in F1 with the amount of turbulent air. The car ahead creates a drag reduction by creating an area of negative pressure, the fact there are two cars does not mean there is an additional effect.

There is no "negative pressure". There is pressure and there is less or more pressure. Once you get to zero pressure, that's it. Negative pressure doesn't exist (in the macroscopic world in which race cars work, anyway).

Tow is not about pressure, it's about resultant air flow direction. A car travels through still air. The air interacts with the car's surfaces and is deflected in various ways. The car pulls the air with it - that is what results in a resultant reduction in air speed felt by the following car. Drag is proportional to the square of the velocity. By dragging some of the air forward with it, the lead car reduces the effective air velocity of the following car. Thus the drag of the following car is reduced.

This effect is nicely demonstrated by the effect that wind has on the cars - a headwind in to a corner allows later braking. A tail wind requires earlier braking. Why? Because the head wind means more downforce, the tail wind means less downforce. Why? Because downforce changes with the square of velocity. A head wind increases the velocity, a tail wind reduces the velocity. A 40% change in air velocity gives a doubling / halving of downforce and drag.

Power absorbed by drag increases with the cube of air velocity. So a small reduction in velocity - such as caused by a car ahead dragging air with it - reduces the power required to overcome the drag. And so the car's speed can increase until the drag absorbs the power again.

Two cars will pull the air with them to a greater degree than will one car. Hence two cars can increase the tow effect on the third car because it experiences a more reduced effective air velocity than the second car.

Thank you… Loved the explanation


Sent from my iPhone using Tapatalk

[PlatinumZealot]

There is negative pressure in a sense. Pressure a scalar but pressure force is a vector.
But I get what you mean.

There is no negative pressure. Pressure is zero or greater.

You can have a pressure difference, of course, where one pressure is lower/higher than another pressure. But that's not negative pressure.

Just semantics though as the term negative pressure is a commonly used even in engineering.
The terms is what it says, just a way to say the force from that pressure difference goes in the inward direction that is opposite to an explosion/expansion/blowing out.

Just for interest a physicist might tell you that antimatter can make negative pressures

[Stu]

Lower relative pressure is the phrase that should be used!
Even a vacuum is not negative pressure, just as close to zero as can be created!

[maxxer]

Lower relative pressure is the phrase that should be used!
Even a vacuum is not negative pressure, just as close to zero as can be created!

What would happen if you get to zero ?