by john jeffery » Sat Apr 10, 2010 5:27 pm
Despite the lack of response on the forum I have received numerous emails asking for clarification of the rules regarding the bulkheads and the cargo space. Either all the forum visitors are extra smart or too embarrassed to ask?
1. It appears that a lot of people (including many Victorian teachers) do not know what the word 'bulkhead' means so I will give the Macquarie Dictionary definition.
bulkhead 1. Naut. one of the upright partitions dividing a ship into compartments. 2. a partition built to withstand pressure, as between the airlock and the cabin of a submarine or spacecraft. 3. Civ. Eng. a partition built in a subterranean passage to prevent the passage or air, water or mud.
Get the idea? We want a solid, rigid, vertical wall at right angles to the direction of travel. (No, paper is not rigid by itself.)
Because the car can only be 320mm wide the 200 sq cm bulkhead could be 320mm wide x 62.5mm high so this is as low as you can go. The 100 sq cm bulkhead could be 320mm x 31.25 mm but be careful because the weight block is 50mm high so it won't fit next to this bulkhead.
The car can only be 180mm high so take out the solar array, say 5mm, and the ground clearance, say 25mm, the height could be 180 - 5 - 25, or 150mm high. This means the narrowest bulkhead could be 133.33mm wide x 150mm high, making the 100 sq cm bulkhead minimum width 66.67mm wide, but again, be careful where that pesky 100mm x 100mm weight block is going to fit.
This then sets the limits for your bulkheads. What was so difficult about that? You can use any shape you like, they don't even have to be rectangular, as long as there are 4 straight sides. And you can make them bigger if you like in order to round out, as it were, your bodywork. You can have the big one at the front or back, it doesn't matter.
And don't forget that you can have nothing in this space except basic car wiring and panel ballast.
2. The next tricky word is 'enclose'. Once more, the Macquarie Dictionary.
enclose -closed, -closing. 1. to shut in; close in on all side. 2. to surround as with a fence or a wall.
Again, not hard. You can have any shape you like between the two bulkheads as long as the space is fully enclosed. That means no gaps or holes whatsoever. When the top goes on, and the top can be the solar array, the space must be fully enclosed, but you must have space in there somewhere for the weight block. I don't understand why you'd want to go making some weirdo shape but if your uncle is Chief Aero-dynamicist for Red Bull Racing then who am I to comment.
3. It might affect your car design but be aware that you now have to be able to put the eggs in and out quickly and with the solar array in place. This means that no more can you have a quick fold down panel between the driver's cabin and the cargo space, so be careful.
4. The last thing I want to mention at the moment is the fact that a certain 'expert' in a certain state insists that the solar array cannot go over the top of the driver's cabin. Absolute rubbish. There is no requirement to be able to look down on the eggs, only in from the front and sides over the full 180 degrees. Don't be fooled.