Piastri won the Azerbaijan Grand Prix after a stunning defensive drive against Charles Leclerc.
The pair ran within a second of each other for much of the race with the McLaren driver seeing off several attacks from his Ferrari rival.
During their battle, onboard vision from Piastri’s car shows the top plane of the rear wing appearing to flex – leaning back at high-speed and the front of the flap appearing to lift.
Occurring at speed, it has been suggested the flex created a ‘mini DRS’ effect, boosting the car’s top speed by 3km/h.
“It’s legal,” Piastri declared.
“As long as it passes all the tests. We get testing a lot, and it passes.
Secure your spot today.
“It’s certainly not the magic ticket or magic bullet for why we’re competitive, but it’s legal.”
Flexible wings have been something of a hot topic this season with allegations multiple teams are exploiting the practice – some more than others.
The technical regulations measure the flex in wings through a static load tests.
If the wing passes those tests, it is legal under the regulations as they are written.
The FIA has introduced cameras it is using to monitor front wing flex, mounted to the nose and pointed towards the end plate, though they serve no regulatory value.
While confident the wing is legal, Piastri admitted he only learned of its new party trick following his Baku win.
View this post on Instagram
“The first time I knew it did that was the same time as everyone else, last week,” he confessed.
“And it’s not a grey area. It gets tested every week. It’s legal.
“They’ve got a lot of different tests for the rear wings now.
“Obviously, in this sport, you find every bit of performance that you can without breaking the rules.
“We’re doing that. That’s what you need to become a championship-winning car and championship-winning team.”
While adamant there is nothing wrong with the wing, Piastri understands why there is a focus on it given his team’s recent performances.
McLaren heads the constructors’ championship by 20 points after the Australian’s Baku win, supported by Lando Norris who rose form 15th on the grid to fourth.
More on Oscar Piastri and McLaren
👉 McLaren “still not fast enough” despite huge milestone
👉 Piastri declares Azerbaijan “best win of my career”
👉 F1 Upgrades: McLaren introduces sizeable package at Dutch GP
“I think it’s natural,” Piastri reasoned.
“You look at any car being competitive and it always gets scrutinised to the highest level.
“Look at the Mercedes a few years ago with the rear wing, and the infamous 50K touch; look at a lot of the teams trying to work out Red Bull’s DRS effects for the last couple of years; flexi front wings in the past and all sorts.
“Naturally there’s going to be scrutiny of just people curious to know why your car is competitive.
“I don’t think it’s personal to us,” he added.
“We’re not just thinking that we’re the best out there and we don’t need to learn anything from anyone else – we’re always looking at the other teams as well.
“And when you’re at the front, and when you have a car within a second of yours for 30 laps and the rear wing camera on there for 30 laps, then naturally people are going to notice it more, too.”
For its part, the FIA is aware of McLaren’s rear wing and is monitoring the situation.
“The FIA is closely monitoring the flexibility of bodywork on all cars and reserves the right to request teams to make modifications at any point during the season,” a statement from the governing body noted.
“However, if a team successfully passes all deflection tests and adheres to the regulations and technical directives, they are deemed to be in full compliance, and no further action will be taken.
“The FIA is currently reviewing data and any additional evidence that has emerged from the Baku GP and is considering any mitigating measures for future implementation.
“This is part of the standard process when scrutineering technical legality, and the FIA retains the authority to introduce regulatory changes during the season if required.”
Discussion about this post