Before we start cutting metal, we need to know that our design is going to meet our weight target. Normally with a racing car you would be building it as light as possible. With gravity racing, that is not necessarily the case, but more of that later. As I’ve mentioned before, the maximum allowable weight dictated by the rules we are building our car to is 100kg, but if the chassis comes in at 75kg, then we are unlikely to save enough weight on the other bits to meet that target. Dexion and plywood are not the lightest of materials, although I’m still reasonably confident it won’t be cripplingly heavy. But to make sure I’ve put together a simple spreadsheet.

Each component is listed down the left and the estimated length of Dexion or area of ply is put in. I’ve arrived at these figures by scaling them up from our model. They are not going to be totally accurate but can be fine tuned as we make progress. For now they give a ballpark figure and I’ve highlighted them in red to show they are just estimates. I’ve then weighed a piece of Dexion to find a figure for its weight per metre and the same for the ply to find a weight per square metre. These figures are then used in formulae to give actual weights. Excel keeps a running tally of these with a grand total.

Currently the figure is sitting at 19.014kg, less than 20 per cent of our target weight. Not bad for the single biggest component on the vehicle. As work progresses, I’ll be adding more to the spreadsheet and keeping an eye on the running tally. For the moment, though, it looks like we may be carrying quite a bit of lead if we decide we want to run at the maximum allowable weight.