Bulkheads

These are barriers between various parts of the car, they may have minimal holes for ventilation or to allow controls to pass through but are otherwise solid and usually help the integrity of a vehicles structure by increasing rigidity.

Please note regulatory content below may be out of date. Please check the current Regulations for the latest information.

The Greenpower regulations specify bulkheads in a few key areas:

1. Separating the driver from the wheels.  For cars with wheels outside the lines of the bodywork, such as the Greenpower kit car, this is provided by the normal bodywork. Cars with internal wheels or flush with the bodywork will usually have the wheels very close to the driver, to prevent accidental contact or debris being thrown into the cockpit there must be a solid structure in the cockpit around each wheel. In this instance the structure may be relatively light, 3mm plywood, 1mm aluminium, or 1mm glass or carbon composites is suitable.

2. Separating the batteries from the cockpit. The batteries are heavy, contain a small amount of acid, can produce explosive gases and are a potential fire hazard if a short circuit occurs. For these reasons not only must they be rigidly fixed to the vehicle chassis they must also be physically separated from the driver as per:

“T2.7. The main batteries must be separated from the driver by a bulkhead, sufficient to restrain the batteries from the driving compartment. This bulkhead must not be able to short circuit the battery terminals.
Batteries must be located inside the vehicle’s bodywork.”

This requires a far stronger bulkhead than in section 1. A minimum 4mm good quality plywood or 1.5mm aluminium or composites. In some vehicles the battery compartment intrudes into the cockpit, this is acceptable as long as it is sufficiently strong to restrain the batteries and is fully sealed from the cockpit. Metal or carbon fibre must be covered with a suitable insulating material to prevent shorting the battery terminals.

3. Forward of the driver's feet. This is the most critical bulkhead in the vehicle because it forms the mount for the energy absorbing nose:

T7.1. There will be a solid, rigidly mounted bulkhead forward of the driver’s feet. Securely attached to the front of this bulkhead will be a foam structure at least 200mm long and with a compressive strength of 300 – 700 kPa. A means of access to this foam must be available at scrutineering.
Advance Notice – 2020 Regulations - T7.1 will be amended to read: There will be a solid bulkhead rigidly mounted forward of the driver’s feet forming the front-most part of the driver’s cell. This bulkhead must be vertical and parallel to the front axle centre-line. Securely attached to the front of this bulkhead will be a foam structure at least 200mm long and with a compressive strength of 300 – 700 kPa. A means of access to this foam must be available at scrutineering.

Note, this does not necessarily have to be the bulkhead immediately ahead of the driver's feet, some cars have a battery and/or steering compartment in this location and then the main impact bulkhead; this is perfectly acceptable.

Materials should be a minimum of 8mm good quality plywood, 3mm aluminium or composites, or 1.5mm steel. It is very important to fully integrate the front bulkhead into the rest of the vehicle's structure by fixing securely on all sides.

Gary Coulden Smith