Last year I was able to acquire a piece of the PS01B and one of the last developments Brunner and his team put on the Minardi, the blown diffuser. Blown diffusers were not new; indeed they had gone out of fashion that very year, as the periscope design was the trend.
I started covering F1 on a regular basis back in 2000. At the end of 2001 I was lucky enough to visit the Minardi factory in Faenza. I had been a fan of Gustav Brunner’s design work for many years and although he had left Minardi by the time of my visit, I did get a chance to see his handiwork up close for the first time. I wrote about my visit and meeting with Gabrielle Tredozzi at the time).
The PS01 had started the year with exhaust passing through the rear suspension to reach the diffusers trailing edge for a light blown effect. Introduced at Spa and run at the last races, the PS01 was updated to the PS01B with this blown floor concept incorporated into it (driven by Alonso, Marques and Yoong)
Having hardly any budget, the team were running a down-on-power engine compared to their rivals and had very little in the way of aerodynamic testing. I recall the calendar pinned to the Wall in Tredozzi’s office showed a few weeks blocked out, that denoted they were testing at Fondmetal’s tunnel.
Brunner was an experienced designer and a lot of his work was empirical simply drawn, made and put onto the car. Resources did not allow much in the way of research, simulation and physical testing.
This blown diffuser solution followed this approach. The exhausts were brought in close to the gearbox and then entered this fabricated metal section. This part formed the central boat-tail of the diffuser, tucked down in the central tunnel where the stepped floor converges to a pointed tail under the car.
By blowing the exhaust gasses through the diffuser downforce would be produced from the greater mass flow under the floor, created by the underfloor flow being entrained with the exhaust plume.
Most likely made from Inconnel or Titanium sheet, the part is hand crafted from flat sections, welded to form the final complex aerodynamic shape.
To create the blown effect inside the diffuser, the part has to merge the two exhausts and direct them to blow along the same axis as the floor. Interestingly it did not seek to align the flow with any surface, merely joined the exhaust plume to that flow through the diffuser tunnel.
To fit in with the exhaust rear mechanical set up, the exhaust outlet needed to provide a tube for the external starter motor to pass through to reach the gearbox.
With Tredozzi designing an all new PS02 for 2002, the throttle sensitive blown diffuser was dropped for periscope exhausts.
On a side note, I have been trying to track down Gustav Brunner for another interview for many years, does any one know where he enjoying his retirement nowadays?