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Date of Award

Spring 1999

Document Type

Thesis - Open Access

Degree Name

Master of Science in Aerospace Engineering

Department

Aerospace Engineering

Committee Chair

Prof. Charles N. Eastlake, P.E.

Committee Member

Dr. Tej R. Gupta

Committee Member

Dr. James G. Ladesic

Abstract

At speeds approaching 240 mph, drivers of open cockpit race cars frequently experience large aerodynamic forces which act on the helmet. These forces, specifically the aerodynamic buffeting of the helmet, reach levels which are very fatiguing and distracting to the driver, and are therefore unacceptable. Little investigation has been done in this area, because normal wind tunnel tests do not isolate the helmet from the rest of the car. During this project, measurements of aerodynamic forces acting on a helmet inside a race car cockpit were made to determine the cause of the buffeting, and to determine possible improvements.

Tests showed that the sources of buffeting are turbulent separation at the rear of the helmets as well as unsteady flow in the region between helmet and headrest. Best improvements were made by preventing separation on the rear of the helmet through the introduction of a fairing, and by limiting the amount of air flow to the rear of the cockpit through modifications to the helmet and cockpit region. While the drag experienced by the helmet doubled to 2 lb through these changes, the lift was reduced from 4.8 lb to 2 lb, and the buffeting force from 5.6 oz to less than 1 oz. This represents improvements of over 60 and 80% respectively. These changes were considered to be acceptable within the regulations of the sanctioning body.

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