This post was contributed by Henk Ormel, who has been a much beloved member of our community at Wheel Sports and an incredibly insightful eye for feedback on technical matters.
There are now 4 teams that use a sidepod with a gutter on top of it. These are McLaren, Alpine, Aston Martin and Mercedes. Ferrari and Haas doing something different. This raises the question why, and why does it work on the AMR quite well and on the Alpine and McLaren not so much.
I think this does hang together with the rear suspension lay-out. The AMR does have pullrods in the rear and the Alpine and McLaren pushrods. With the gutter in the sidepods the air does have a more longitudinal direction and the main flow is just a little more to the outside. There to the outside is the bottom linkage point for the pushrod. This does create more drag.
To sidestep a little, the Red Bull does have pushrods in the back and no trenches. The main airflow over the diffuser is somewhat more in washing to keep the suspension pick-up point in low(er) velocity air.
McLaren had the same idea as Red Bull had before 2022, pullrods in the front and pushrods in the rear. McLaren did combine this with inwashing sidepods which seemed to be a good idea back then. Unfortunately the inwashing effect did reach too high so whatever suspension system McLaren had mounted it would always be inside the high energy airflow. Halfway the season McLaren came up with a change in concept, downwashing sidepods with a trench like the Alpine had. Unfortunately this didn’t work either, the Alpine last year still had a rear pullrod system. For this year McLaren did stick with the pushrod, the downwashing sidepod, the gutter inside it, and a notch like the Red Bull to spill air to the outside. The airflow to the diffuser is a mess. I wonder if there is someone who is vaguely aware off what they are doing upthere.
The Alpine system seemed to work quite well last year so there were high hopes for this season. The car looked stiff, clumsy and draggy in winter testing. Alpine switched from a pullrod rear suspension to a pushrod and developed the trenches even further. This didn’t work that well together. It does seem it is now reasonably fixed by tweaking the outside wall of the gutter.
And now Mercedes.
This is the first of the gutter concepts which has cooling louvers inside the trench. This is great for pulling air thru the radiators but it does leave a messy wake. That messy wake is supposed to power up the top off the diffuser and the beamwing. This in my opinion is a big ask. The upper SIPS is as decent as possible integrated in the top of the sidepod but it is not stellar seeing the first pictures on Tuesday morning before the Monaco GP.
It became a little more than just trenched sidepods, it is how my brain works.