'Fundamental' issue with Force India's F1 car is holding it back

The Silverstone-based F1 team has had a difficult start to the season, struggling for pace and scoring only one point, thanks to Esteban Ocon's 10th place in Bahrain.

Force India has been chasing a cure for an issue that first emerged in pre-season testing, which has held back aerodynamic development.

"It started probably between the Barcelona tests and Melbourne," said technical director Andrew Green.

"We were a bit dubious about the data we were receiving, whether it was real or not, and then we needed to perform more tests on the car and some additional logging, instrumentation, to see if it was a real phenomenon or not.

"Everything we have seen so far suggests it is real, so we have been attacking it to try to instigate a change, but as of yet we have yet to make any real inroads into it."

Green said the early indications of what he refers to a "fundamental underlying issue" pointed to its CFD and windtunnel data not aligning with how the car has performed in the real world.

"It is not a tunnel issue, it is a full-size issue," he added. "It doesn't match tunnel or CFD.

"The tunnel and CFD match, but unfortunately they don't match reality."

Green said that the fluctuating balance at the rear was also making it difficult to evaluate other car parts, like the new front wing trialed in Bahrain.

"We are still very confident the front wing does what we wanted of it," he said.

"But it was designed to go with a car that generates more rear load, which we don't have at the moment.

"Once that load appears and you put the wing on, that generates even more rear load so it is a double whammy."

Green said it was "incredibly difficult" to judge Force India's potential because "it is very difficult to manage the rear tyres when you have a fluctuating rear load".

He hopes an update planned for next month's Spanish Grand Prix will help cure the problem, but admitted it could be more serious and related to its underlying car concept.

"With a clean sheet of paper we could probably solve it straight away, but we don't have a clean sheet of paper, we already have a car that exists," Green said.

Renault Sport chief technical officer Bob Bell said it was "surprising" how far back teams like Force India and Williams are this season, but said things could change quickly if they discover the root cause.

"Sometimes you can push it a little too far and the windtunnels or CFD don't tell you the truth and you just go over the edge," he said.

"When you discover what that is and you fix it you can take quite a step forward."