Formula 1 is a world of change, yet Monaco is a beacon of stability. Everything about the place remains near-unchanged: the race date, the track layout and the demands on the cars.
If you look at any Monaco preview or debrief, the issues remain the same - cars searching for grip, with heavy demands on the transmission and hard work for the suspension.
Even though teams traditionally say Monaco is not a place to introduce new developments, there was a raft of new parts seen on the cars for the first practice sessions on Thursday.
The track demands maximum grip, both mechanically and aerodynamically, and teams will not worry about the inherent drag affecting top speed. Instead, they will add as much downforce as they can to their cars.
Many teams have revised wings this weekend, but there is a special compromise that is not normally available to them...
Since DRS was introduced in 2011, teams have increasingly sought to reduce the size of the rear-wing flap in order to gain as much speed as possible.
When the DRS is activated, the top element of the rear wing pivots from its trailing edge to open up a maximum gap of 50mm to the lower wing. Usually, a smaller top flap is used. This is designed to open up to be nearly flat at speed, to maximise the reduction in wing area and provide a greater top speed. But in Monaco a larger one can be used.
DRS arrangements can be tweaked to help with downforce in Monaco © XPB
This compromises the wing when DRS is not being used. The slot gap between wing and flap is further back along the wing, and the slot prevents the airflow separating under the wing, so therefore the rear wing cannot produce maximum downforce.
For Monaco some teams have gone back to a larger flap, as the DRS effect in Monte Carlo is of no real advantage thanks to the short straights.
Force India tested its large-flap wing in a straightline run. The larger flap means the slot gap is further forwards on the wing, so the wing can be steeper and create more downforce, without fear of separation.
Ferrari brought a revised rear-wing set-up to Monaco, comprising a new top rear wing and Y75 winglet.
The team also ran variations of the sidepods seen at Barcelona, although the revised pod vanes were not run in free practice.
The top wing is a much deeper set-up to provide more angle of attack. It uses the lower-downforce wing endplates, so a large black area of unpainted carbonfibre is exposed, showing how much deeper the wing is.
Ferrari has altered its rear wing © XPB
Another detail evident on the wing is its outer 5mm span where it meets the endplate. Airflow around this right-angled joint is disrupted, so the wing is less efficient.
Ferrari has opened up a slot halfway along the wing to prevent airflow separating underneath it. This is allowed - although the rules demand rear wings of just two elements, in the outer 5mm of wing this restriction isn't imposed.
Below the top rear wing, the Y75 winglet (Monkey seat) has also been updated.
This is a two-element set-up, with the slot formed between the two elements wrapping partly around the endplates. As much as these winglets appear to be for downforce, their effect is much more about connecting the airflows from the diffuser and top rear wing.
This creates a more stable aero set-up for more consistent handling. In Monaco this is important as the top rear wing is set to a steep angle - anything to keep the airflow attached is helpful.
As Red Bull is one of the teams suffering greater rear-tyre degradation, the changes for Monaco were logically aimed at easing this problem around the Principality. The team brought a new rear wing and revised floor treatment ahead of the rear tyres.
Its rear wing follows the practice led by several teams last year, with a vertical slot in the leading edge of the rear wing.
Red Bull is trying to address rear degradation © XPB
As the rear wing has, by regulation, such large endplates, it's hard for airflow to funnel in and out of the duct formed by the wing assembly.
This makes the endplate shape more three-dimensional - flow can enter the wing from the outside, and more flow through the wing means more downforce.
Lower down, the team altered the fence and slots in the floor in front of the rear tyres. The fence appears to be taller, most likely to deter the exhaust plume reaching the rear tyres.
With lower average speeds around Monaco there is less aerodynamic effect diverting the exhausts gases into the right area.
With this change, the slot that diverts high-pressure air towards the inner face of the rear tyre has been altered too.
This slot sends a jet of air along the inner face of the tyre, and this prevents the tyre's wake passing into the diffuser and robbing it of downforce.
Williams is in better shape in Monaco © XPB
Monte Carlo was always likely to be a track where the FW35's aero weaknesses would be offset by the car's relatively strong mechanical grip. Therefore, the team's changes appear to be minor for this race, with a revised front-wing cascade the main difference.
This winglet, mounted to the front-wing endplate, was already upgraded to a three-element part earlier this year.
Now the two slots splitting the winglet curve up so that the endplate is also a three-element piece.
It can be clearly seen that these three vertical parts form fins to direct airflow around the front tyre.
Tyre temperature is crucial for Mercedes © XPB
Another team with tyre-degradation problems at the forefront of its mind, Mercedes ran Lewis Hamilton's car in Thursday practice with some unique tyre-temperature sensors.
The team fitted infrared sensors to the front-wing cascades. These face back to measure the temperature across the full width of the front tyre.
Normally, such sensors are fitted in the wing mirrors or pod vanes. Having the sensors in this position means a more accurate measure of the temperature can be read.
Curiously, the more sensitive rear tyres did not gain an additional sensor as the usual sensors embedded into the floor ahead of the rear tyres were used.
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