D. Composite Chassis Safety Structures
1. The basic purpose of safety structures is to protect the driver.
This purpose is the primary design consideration.
2. All cars must have at least 2 roll over structures, but the use
of titanium is prohibited.
The first roll over structure must be in front of the steering
wheel, not more than 25cm forward of the steering wheel rim,
and at least as high as the top of the steering wheel rim.
The second roll over structure must not be less than 50cm
behind the first. It must be high enough for a line extending
from the top of the front structure to the top of the rear structure
to pass over the driver’s helmet when he is seated normally
in the car with his helmet on and the seat belt fastened. This
GCR - 120
9. Cars and Equipment
second structure behind the seat must be symmetrical about
the lengthwise centerline of the car and comply with the
following dimensions: The top of the roll bar must be at least
2 inches (5cm) above the driver’s helmet when the driver is
seated in a normal driving position. No second roll structure
on a composite chassis will be considered unless it contains
a main hoop having a minimum tubing size of 1.375” x .080”
wall thickness. Supplemental braces must have a minimum
tubing size of 1.00” x .080” wall thickness.