Interesting bit I found while reading an article where Sam Collins touches on how RB has been able to bring some significant aero related upgrades (new sidepods), while working around the restricted wind tunnel time.
"What Red Bull have done here is quite interesting, because they've read the rule book and that's a really important thing to do. So by changing this side pod duct, what they've also changed is everything that's underneath this side pod. All of the coolers, all of the radiators, all those heat exchangers, everything related to cooling the power unit has been changed. And the regulations are really interesting on this point because when you change those parts, when you develop new radiators, you develop new ducting underneath the bodywork, that does not come out of your wind tunnel or CFD testing allocation. You can spend as long as you like in the wind tunnel developing the radiators, developing the ducting to the radiators, as long as it's related to cooling the power unit."
"They're not allowed to put any force measurement, so they can't measure how much downforce that may be generating, but they can measure the flow through the side pod, they can measure the temperature, they can measure the different air pressures throughout the side pod. So they can learn a huge amount about how these new side pods will be working. And that's what they've been doing, that's how they've been able to introduce this dramatic upgrade to the car."
