Schwitzer Prize Winners Are Raising A Flap At Indy

by Allan Brewer

Rahal Letterman Lanigan Racing’s Indy 500 rookie Spencer Pigot crashed his bright yellow and red car during practice at Indianapolis Motor Speedway on Wednesday May 18th, but in so doing he provided significant evidence that IndyCar’s off-season search for a cure to cars taking flight on the Speedway was a fruitful pursuit towards improved safety and better racing technology.

After suffering a puncture of two tires, the No. 16 Dallara/Honda spun in Turn 1, got backwards at speed, struck the left side of the chassis into the SAFER barrier, and slid down-grade from the banked surface into the grass at the corner’s apex. Pigot was unhurt in the hard impact, mercifully, but of nearly equal gratification was the fact that the car (even though it was traveling at over 200mph during its backwards motion) failed to lift off the ground and into the air.

Open-wheel cars in flight were a problem at Indianapolis in 2015, the first year of specialized aero kit manufacture by the Honda and Chevrolet teams. Chevrolet and their aerodynamics partners at Pratt and Whitney were particularly vexed by the occurrence, most famously when Ed Carpenter went into the fence at Turn 1 around the racing surface prior to Saturday Indy 500 qualifications at the Speedway and precipitated a long meeting between officials and Chevrolet about the suitability and safety of their machines on the oval.

Some innovative thinking from a talented group of aerodynamicists, carbon-fiber fabricators and engineers with training in computer fluid dynamics (CFD) led to the new rear beam wing and flap devices that won today the 50th Louis Schwitzer Award for engineering excellence from the Indiana Section of the Society of Automotive Engineers International. And it is this craftily-designed wing structure that kept Pigot planted to the ground when he crashed earlier this week.

Similar in principle to the pop-up rooftop hatch on NASCAR vehicles that is meant to catch the air and impede lift at high speed, the Indy wing and flap deploy when a car is moving rapidly at speed in a rearward direction. In the 2015 rear wing design implementation on the Dallara DW12, air became trapped under the backwards-moving car and created lift to bring the entire chassis off the track and upwards—sometimes into the catch-fence where anything can happen and none of it is good.

Now, a spring-loaded flap integral to the rear wing itself is forced up to block the flow of air and effectively bring the car to a halt when it is moving backwards; and in so doing force it back to ground where brakes and tires can slow its course. Once the direction of airflow is normalized, the flap collapses back down into its normal position flush with the rear wing and aerodynamic downforce is re-established, further aiding braking and steering control. In practice the new wing flap is reminiscent of an alligator opening its jaws, the roof of the mouth acting as a brake on the airflow, with the lower jaw constituting the stationary, chassis-mounted and fixed rear wing structure per se.

IndyCar technical bulleting #10.00 describes the mandatory change required of every car running at a SuperSpeedway (Indianapolis, Texas, Pocono) on the 2016 schedule. Tino Belli from IndyCar (a previous winner of the Schwitzer Award for his work on the micro-tubule radiator system introduced in2010), Arron Melvin from Pratt and Miller, and Alex Timmermans from Dallara received a $10,000 prize from Borg Warner for their work on the project.

This is the 50th year the Schwitzer Award has been granted, and the names of the recipients is a veritable “Who’s Who” of the greats of automotive and aerodynamic innovation in the twentieth and twenty-first centures: Jim Hall, Colin Chapman, Bruce McLaren, Mario Illien are just a few of the luminaries who have been feted by the Indiana Section of the SAE International at Indianapolis. Borg Warner is an international powertrain and technology company that provides the turbochargers that will power every car in the 2016 Indianapolis 500 field.