The Italian Grand Prix is now a unique event on the calendar - with its high-speed low-downforce nature not matched anywhere else in the season.
The weekend produced some interesting solutions to the trade-off between drag and top-speed - which was further complicated by the widespread use of F-ducts.
F-duct versus no F-duct
There was a lot of talk in the build-up to the weekend about whether teams would stick with their F-ducts or remove them from their cars.
In the end, out of the frontrunning teams, it was only Lewis Hamilton who opted to take the F-duct off his car and gamble on an ultra low-downforce configuration.
Lewis Hamilton's F-duct-less rear wing © autosport.com
Ultimately, whether it is a small rear wing or a big rear wing, an F-duct will contribute to drag reduction. The issue at Monza was that it was a finely balanced choice between wanting to use the F-duct for a drag reduction or for a downforce improvement.
At McLaren, Jenson Button went for more downforce to bring him back into the ballpark in terms of straight-line speed. But I think the ultimate problem McLaren had was that it didn't make a wing that was specific to Monza. It had a Montreal-type wing assembly and, because Monza was just a one-off, it probably served its purpose.
Ferrari, on the other hand, developed a specific rear wing package for its home race - which included a revised F-duct with a smaller airflow tube. Because the rear wing is a lot smaller at Monza, the wing needs a lot less airflow to work - so hence that smaller tube.
McLaren wing detail
McLaren rear wing detail © autosport.com
Although McLaren did not bring a specific Monza wing, the low downforce version Hamilton ran was still impressive in terms of its detail - which took inspiration from the version run at the track last year.
With a short main plane, the centre pressure is much further back - which means for less downforce you have higher leverage.
If you look closely at the detailing of the endplate and the flap, all the elements there are about reducing drag. Normally you would get quite a bit of drag from the air pressure building up underneath the main plane, from on top of the flap and from the upper edge of the endplate. If these all joined up, then you would get a twisting action, which would create a vortex, and that is quite draggy.
McLaren's arrangement aims to minimise that, with the slots in the endplate aiming to equalising the speed of the air through the various areas of the wing.
Mercedes rear wing © autosport.com
If you compare this detail to the Mercedes GP arrangement you can see quite a difference. The Mercedes GP has a short-cord main plane and you can see a big Gurney flap on the trailing edge. That Gurney flap has probably been introduced because the car has a braking instability - so it would increase the downforce, move the centre of pressure a bit rearward and give the drivers a bit more stability - as it is like having a parachute on the back.
The difference in top-line speed between what McLaren did with the detail on its wing and Mercedes without it is probably only about 1-2 km/h. That gives a clue to the enormity of the work that F1 teams have to do nowadays to make everything function. It's time-consuming effort to optimise things like this for what is ultimately a small return.
In terms of brakes, Monza gives teams some major problems. You have to make sure you can have a lot of brake disc material to absorb the high impact temperatures, while when you whistle down the straights at 350km/h then stamp on the brakes you give the discs a massive temperature shock.
That is why Monza is one of the tracks where teams spend a lot of time experimenting with holes in the brake disc structure.
Having one hole there would give you some good cooling, but could weaken its structure. By putting three rows of holes in there - like Ferrari did here on Fernando Alonso's car - you have a structurally better disc because there is more of a mass of carbon. However, it is a very complicated thing to machine and make.
If you take away the mass of the disc by just drilling one big hole, then the disc cannot cope with the temperatures as well. Ultimately you are looking for the compromise between having the disc as heavy as possible, but with the maximum surface area to allow for cooling. It's very complicated!
Ferrari front wing
Ferrari's new (top) and old wings © autosport.com
As part of Ferrari's aggressive development updates for the Italian Grand Prix, it ran a new wing - with the new version pictured here on the top with the older version at the bottom.
The main plane on the old wing is longer and more aggressive, and the change away from this will have been motivated by trying to improve the balance of the car because of the overall reduction of downforce at Monza.
Ferrari felt it better to have a less aggressive main plane and a straightforward slot gap - because you are trying to lose front downforce at Monza but doing so without hurting the rear of the car.
While other teams would have been doing that with flap profiles or trim angles, Ferrari actually tweaked the main plane to get better flow to the back of the car. When we go to higher downforce tracks like Singapore, it may use its old wing concept again.
New floor tests
After the controversy over flexi-wings that marred recent races, the matter finally went quiet at Monza when the FIA introduced new floor deflection tests.
Close-up of the critical flexi-test area on the Mercedes © autosport.com
The new tests, which involve testing the flexibility of the floor in an area either side of the car's centre-line, forced teams to introduce new stays to ensure their bodywork was not deflecting. Here you can see the solution that Mercedes GP introduced.
A lot of people were wondering whether Monza's characteristics would have hidden any performance implications that came from the tweaks teams had to make, but I am not sure.
If teams had been running flexible wings, then I think their benefit would have shown up at Monza as well as anywhere else. I find it hard to believe the teams were able to flex their floor enough for it to have been a benefit in getting the front wing lower to the ground, so I don't expect the new tests made much difference - other that it finally shut people up complaining about each other's cars.
Renault's new front wing © autosport.com
We've seen a lot of impressive work from Renault this season on its front wing design, and it is clear the team has got a good grip in understanding this area of the car.
At Monza, it ran a cut-out V section in the front wing which would have been to set up a vortex. Training such a vortex to flow into a specific area of the car can provide a team with an area of good high-energy airflow - and I think Renault was focusing this flow for its brake duct area.
While some of that may have been aimed for cooling, we've seen brake ducts being used for fitting items that also help with downforce - so perhaps this is what Renault was also looking at.
Either way, getting that air turned around inside the front tyre will have been a big help - especially for setting the flow up for the rest of the car at a track where good aero-efficiency is vital.