The much discussed new-for-2016 domed skidplates will remain in place for the 100th running of the Indy 500, but IndyCar has made an underbody concession.
Last week’s tests at Indianapolis Motor Speedway saw cars running with and without domed skids, and with and without underwing strakes.
However, IndyCar today stated that it “maintains its position spelled out in the 2016 Verizon IndyCar Series Rule Book mandating the use of domed skid plates and prohibiting the use of underwing strakes on all cars in this year’s Indianapolis 500.”
Domed skids, as well as beam-wing flaps to prevent cars launching, were written into the rulebook as a safety measure for this season as a result of the three crashes last year during the Month of May. The cars of Helio Castroneves, Josef Newgarden and Ed Carpenter got airborne after spinning backward during practice.
The idea of domed skids devices, which bulge downward, is to slow down the rotation of a car once it gets into a spin. As the air travels under the the car while it is at an extreme yaw angle, it speeds up as it gets constricted under the dome. This creates a low-pressure area which effectively sucks the car onto the track surface via hugely increased downforce, reducing the chance of lift and rapidly slowing the rate of spin.
However, the domed skids have been a bone of contention, particularly for Honda-powered drivers, since HPD’s superspeedway aero kit is reported to work less well with domed skidplates than the Chevrolet kit.
In addition there have been fears expressed that skids will hurt the racing, since with their ride-heights raised to accommodate the domed skids, the cars have less efficient underfloor aerodynamics, and are therefore relying more on top-surface aero for their downforce. The theory is that the cars are therefore far more affected by turbulence when running in close proximity with each other.
Underwing sidewalls concession
The IndyCar statement added: “Following extensive data evaluation following the aero kit test at Indianapolis Motor Speedway… IndyCar is permitting manufacturers to lower the optional underwing sidewalls by 9 millimeters (0.354 of an inch) for the 100th Running of the Indianapolis 500 presented by PennGrade Motor Oil.”
Dale Coyne Racing’s Michael Cannon, race engineer for Conor Daly, explained to Motorsport.com: “At the tunnel exit nearest the rear tires, there is a removable sidewall. We don’t use it on the road circuits or most ovals.
“Typically you run them all the time and then for a qualifying run, if you want to really trim that last little bit, you’ll go to a half-height sidewall. It’s actually a very inefficient way of trimming downforce but it’s there if you want it.”
Cannon said that although the strakes would have added yet more downforce, these lowered underwing sidewalls would still make a noticeable difference in the raceability of the cars.
“We haven’t tested the cars in this form, so we head into May with that unknown so it’s difficult to say how much downforce will increase. But you know, underside downforce increases almost exponentially as the cars get lower, as the sidewalls try to seal the gap between the car and the ground. So I think this should be a nice little step that should allow for good racing.”