Mercedes W13

[ing.]

Here you go:

https://i.imgur.com/pwYc0BH.jpg

Merc on the left, Red Bull on the right.

Edit: Right click and open in new tab to see full image resolution. The Merc image was rather low res compared to the Red Bull's photo, but I did enlarge the Merc's to the Bull's resolution.

Seems to me the roof of the RBR tunnels are very much arched in section whereas the Merc has a lower, wide and flat roof (in section) and also flat along a good portion of its chord.

The low, flat roof of the Merc would appear to make the flow more sensitive to ride height variations. At full bump, for example, the area will be reduced quite a bit more—assuming the width of the tunnels on both cars is similar. The Merc is turquoise and the RBR is purple:



With the Merc floor seeming to be flat along most of its chord ahead of the rear axle—as opposed to a more cambered wing-like profile—this would tend to make it more pitch and heave sensitive. As explained already by Migeot in the Autosport article, due to the cars having more suspension travel at the rear, heave displacement at full bump resembles a nose-down pitch attitude. With a flat floor, the throat moves aft and any blockage due to boundary layer build up would get exacerbated and so would affect total DF and CoP location. Front is —>



This may explain why Merc have good numbers in the wind tunnel that don’t translate to results on track. Kind of like the extreme GE cars of the late ‘70s like the Lotus 80 and the Arrows A2.

[ing.]

To be a mass damper the floor has to vibrate in opposite phase to the air flow vibrations which is impossible because the two are inextricably linked.

Something else has to be the mass damper and you can imagine it will be some big amount of weight to push the car down when the car wants to bounce upward.

You could make one out of a cantilevered weight in the sidepods but it could constitute a moving part. Mass dampers are banned anyway.

The fact they needed to add the stays to the floor edges tells me that the floor is not necessarily moving in phase with the body of the car. And, yes, the weight required to make such a thing work may render the idea infeasible and probably cause flutter problems even though the mass ratio of the added weight may be a small percentage of the car weight depending on the stiffness of the “spring” or flexible structure.

You could imagine that the floor edges moving in opposite direction to the floor movement may be desirable if it can be controlled. For example as the body of the car is accelerated upwards from a bump the floor edges would lag this motion (especially if weighed down) and maintain a seal to the ground as car moves up. And as the body of the car is downwards during a bouncing cycle, the floor edges would lag and not seal the underbody as the car drops down.

This is all speculation and free-thinking with no calcs to back this up, of course.

[PlatinumZealot]

To be a mass damper the floor has to vibrate in opposite phase to the air flow vibrations which is impossible because the two are inextricably linked.

Something else has to be the mass damper and you can imagine it will be some big amount of weight to push the car down when the car wants to bounce upward.

You could make one out of a cantilevered weight in the sidepods but it could constitute a moving part. Mass dampers are banned anyway.

Is there not some way of redirecting an air stream when a floor edge flexes? If it let just enough escape would it not counteract the downward movement until next time it was back at that level?

This would than not be a mass damper or movable aero as it is not moved.

Yeah. I think the floor cuts do this to some effect. I cant say exactly how but it must shifting where the centre of pressure is as the cars lower or something like that.

[Sofa King]

Interesting

To be a mass damper the floor has to vibrate in opposite phase to the air flow vibrations which is impossible because the two are inextricably linked.

Something else has to be the mass damper and you can imagine it will be some big amount of weight to push the car down when the car wants to bounce upward.

You could make one out of a cantilevered weight in the sidepods but it could constitute a moving part. Mass dampers are banned anyway.

Is there not some way of redirecting an air stream when a floor edge flexes? If it let just enough escape would it not counteract the downward movement until next time it was back at that level?

This would than not be a mass damper or movable aero as it is not moved.

Yeah. I think the floor cuts do this to some effect. I cant say exactly how but it must shifting where the centre of pressure is as the cars lower or something like that.

[jagunx51]

[atanatizante]

Regarding the suspension, heave, dampers and stuff that could influence porpoising:

[ringo]

Very high tyre pressures could also be a tool. But I do not know the negative impact of doing this with the bigger 18 inch wheels.

[Mchamilton]

Very high tyre pressures could also be a tool. But I do not know the negative impact of doing this with the bigger 18 inch wheels.

Wasnt it slightly higher rear tyre pressures that Lewis tried for Jeddah quali? and he couldnt drive the thing

[ringo]

Very high tyre pressures could also be a tool. But I do not know the negative impact of doing this with the bigger 18 inch wheels.

Wasnt it slightly higher rear tyre pressures that Lewis tried for Jeddah quali? and he couldnt drive the thing

you may be right. There could be a loss of rear grip. especially if the tyres arent in their temp range.

[AR3-GP]

Very high tyre pressures could also be a tool. But I do not know the negative impact of doing this with the bigger 18 inch wheels.

High tire pressure cost you mechanical grip (i.e how well the tire conforms to the deviations of the track surface within the contact patch).

[matteosc]

Very high tyre pressures could also be a tool. But I do not know the negative impact of doing this with the bigger 18 inch wheels.

High tire pressure cost you mechanical grip (i.e how well the tire conforms to the deviations of the track surface within the contact patch).

Absolutely agree. That is why they always run at the minimum allowed (and even lower if they could get away with it) last year.

[ringo]

So that means there will be deflection at speed that the team will simply not be able to precisely control as the floor approaches that critical point.
And this explains why the Ferrari was bouncing in the early parts of the race, and as the fuel load decreased, the car rode higher and possibly the tyre pressures may have changed as well along with their reduced diameter from wear.

Maybe it's possible to have a car that creates sufficient downforce at ride height that has a buffer height above that critical ride height at which the floor chokes.

I would like to hear what Mercedes have discovered, and if they will share the findings. It's likely they wont as it could also help the competition.

[zibby43]

Very high tyre pressures could also be a tool. But I do not know the negative impact of doing this with the bigger 18 inch wheels.

High tire pressure cost you mechanical grip (i.e how well the tire conforms to the deviations of the track surface within the contact patch).

Agreed, but I think they’ve tried pumping up the pressures this season. I believe AMuS reported that this approach was what cost Hamilton in Jeddah. Which explains why he felt like he had no grip or confidence to throw the car around near the walls.

[e30ernest]

People earlier were posting pics of Mercs floor and comparing it to Red Bull's. Can someone post a pic of Red Bull's floor for the side by side comparison?

Here you go:

https://i.imgur.com/pwYc0BH.jpg

Merc on the left, Red Bull on the right.

Edit: Right click and open in new tab to see full image resolution. The Merc image was rather low res compared to the Red Bull's photo, but I did enlarge the Merc's to the Bull's resolution.

your images?

No they are not, I grabbed them from this thread and from the RB thread.

[pierrre]

Here you go:

https://i.imgur.com/pwYc0BH.jpg

Merc on the left, Red Bull on the right.

Edit: Right click and open in new tab to see full image resolution. The Merc image was rather low res compared to the Red Bull's photo, but I did enlarge the Merc's to the Bull's resolution.

your images?

No they are not, I grabbed them from this thread and from the RB thread.

ok thanks for tha info