November, 2006

Improving the air flow to the battery pack

 

Race car aeronautics design needs a 'holistic' approach. Cooling, down force, drag all need to be considered. Air pressure at the front of the car and the rear of the car are both important in influencing air flow through the car.


Here are some of our goals:

  • Cool the motors and controllers with air flow through the stock radiator.
  • Cool the battery pack with air flow through the battery packs, in effect, turning them into radiators
Battery radiator
  • Reduce drag and increase down force with a smooth floor pan and rear diffuser.
  • Reducing drag and encourage air flow through the radiators by allowing the high pressure air at the front of the car to go into the radiator
  • Reduce drag and encourage air flow through the radiators by exhaust air into the low pressure zone behind the car.
   

Air dam 2.0

We start by redoing the front air dam.

battered air dam
   

The main goal here is too open up the blockage to the radiator and smooth out air flow. We use a cutting wheel to trim the bumper beam and then a hole saw to remove weight while still maintaining some of the strength. The bottom plate is replaced and angle aluminum riveted into place to create a smooth curve.

We add a small vertical lip to try and keep air off the front of our wide racing tires.

Creating a new air dam
   

To create the surface of the air dam, we take a pre-made .023 inch thick Carbon Fiber sheet (from the Robot Market Place) and rivet the material into place. If the unsupported area was any greater, we would have to use a thicker material. Working carefully with a heat gun (for bending) and scissors, we are able to get a tight fit.

Air dam 2.0
   

We end up with a lower opening that is 7 inches tall by 29 inches wide (203 square inches). We also still have the upper opening which is 4 inches by 28 inches (112 square inches).

   

Rear Aero 2.0

To create air flow through the radiators, the air has to have somewhere to go.

The opening at the rear of the car is not large enough to assure proper air flow. It is a space of 1.5 inch tall by 44 inches across (66 square inches) directly above the diffuser.

Rear aero 1.0
   
We remove the rear bumper and start cutting. Again we are able to remove a fair amount of weight while still keeping some strength. We increase the opening to about 4.5 inches while maintaining the 44 inch width (198 square inches).
In the trunk, we build a cover to direct the air coming from the battery pack out through the new opening.
Rear aero 2.0

 
 

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