F1 porpoising question.

[Onebadbug]

I am amused but perplexed why F1 can't figure out the problem.

1) Is the floor a set design from FIA they can't change?
2) Why can't you just have a solid stop for the third spring?

I don't recall Indycar having these problems.

[samiam1017]

stiffer springs, maybe?

[phantomjock]

ONCE UPON A TIME...

I was working for a small high-speed racing (boat) team. We were trying to get back the one record that Evenrude had that Mercury did not.
The reason, the Evenrude pilots had big balls (to quote James Hunt). At the speed needed to get the record, the boats would become unstable and flip - frequently with fatal results. My boss, a former fighter pilot wanted "wings and things." For the initial trials all went well, but the boat was under powered. Mercury sent a new engine. Then, it all went south. At 85 the boat would begin to porpoise. I said to my boss, the owner/driver, just push through it. I believe we've got an unstable lift vector moving forward and aft (a problem well known in seaplane fluid dynamics). I said; "Once you get above maybe 95 it "should" be fine." His answer; "Put your ass in there kid."

Nintey-five across Lake Pelican with the nose up and down several feet was enough for me. I came in and put it on the trailer and told him I'd build a new bottom. [Yes, it worked]

Now, to F1;
https://www.yourdatadriven.com/wp-co...sting-2022.gif


Clearly an instability, but is it a moving lift vector/region, a stalled region, an unstable "bubble" - what ever it is, it seems from the footage to be moving along the center axis. If it is getting too low, it might eliminate the effectiveness of the downforce - effectively compressing the low pressure area, then the springs force it back up, the downforce then "re-engages" and before it cycles, the rear does the same?



Note the diagram of a wing in ground effect (for downforce inverted). If you move lower, the wing (underbody) stalls looses its effectiveness, then up push the springs - less downforce pushing down. I've marked the critical region, and the cusp they might be riding on. If this is the case, they have options.

Stiffer springs - or limit the maximum downward travel of the vehicle, but man, aren't these already pretty much minimum motion suspensions? And, once started stiffer springs would dampen the cycles quicker.

If aids are permitted (I don't follow the rule that much - my SR is SPU you know), might try VGs?
I think you can eliminate:
Side winds,
Wind gusts,
Road topology,
Other cars effecting the air, and
The effect of the front wheels when turned.

Perhaps "tire squirt" could influence the under body - and could try more "air curtain" with front wing (again - don't know rules).

If it were me - I'd be building a new bottom after that run. (man, I wish I could afford some wind tunnel time)

Cheers - Jim

[2BWise]

stiffer springs, maybe?

Except the tire. The tire is part of the issue. Go too stiff with the springs and the tires become all of the suspension motion and they are undamped, so when the sprung mass reaches its natural frequency and there's no way to modify the rate or damping of the tire what can you do? Serious question. You can add mass to change the natural frequency but a heavier car is slower. Take aero load off the car but that'll make it slower. It's a perplexing issue and I'd love to be a fly on the wall as they figure it out.

[Rick Kirchner]

Used to see this on sports racers in the 80s before people worked out the fine details of downforce. They'd put a big splitter on the car, which would push the nose down, stall the airflow under the car, nose would pop up, lather, rinse, repeat. I remember guys coming down the front straight at IRP going chit-chit-chit-chit at about 3 Hz.

On a SR and sedans the solution is to give up some downforce with a raised section in the middle so that you can't bury the splitter and stall the airflow. That's covered in McBeath's book.

In F1, I'd wager it's softer springs and more travel now that they don't have as much tire sidewall to deal with, and doing the usual thing of trying to eck out every last iota of performance even when it's obvious that doing so has negative consequences.

Reminds me of an old joke:

Patient "it hurts when I do this"
Doctor "stop doing that"

IIRC they also had this problem in Indycar i the early 80s. You can control it with spring but of course it beats the crap out of the driver in a different way than the porpoising does.

[phantomjock]

Before anyone "runs the numbers" the image I included is specific for an inverted Wing in Ground effect. Not a body in motion.. It shows what I was trying to explain, but a more appropriate image is still using a generic body - but is widely used in academia. An Ahmed body represents as follows:


Note the same critical point on the lift curve. These results are based on the length of the body vs the height above ground. Can't say what a Ferrari looks like, but there are a set of solutions they could try. The ride must be uncomfortable.

Cheers - Jim

[Offcamber1]

in there someplace about fixing the porpoising by adding a little flipper.

Reminds me of an old joke:

Patient "it hurts when I do this"
Doctor "stop doing that"

[chrisw52]

stiffer springs, maybe?

or progressive springs to handle the changes in downforce (high / low speeds)

[DaveW]

or progressive springs to handle the changes in downforce (high / low speeds)

Progressive springs have an effect similar to increasing the motion ratio in bump. In a very high downforce car, that "may" be beneficial. If the progressive effect is too large, at least in cars with relatively low levels of downforce like an FC/F2000, that has been shown to reduce grip.

[Onebadbug]

I guess my idea of having a hard stop, which makes the car a go kart, would reduce grip. Especially with the new low profile tires. A little bump and the car would snap oversteer.
F1 has so little suspension travel, I thought it wouldn't matter.

[Chris Livengood]

Straight line porpoising doesn’t seem to matter much. The Ferrari being the clear example.

Porpoising shuts off the moment the car turns or brakes. Curious indeed. There might be some incentive in letting it porpoise as it maybe reduces drag while under heave only conditions. The Ferrari looks the most compliant of the cars, but it will be interesting to see how that plays out on non street circuits. The RedBull might prove better in sustained high speed tracks like SA.

I’m sure the drivers would prefer a smooth ride down the straights. With a commanding lead I’m sure Charles can deal with it.