D&T6: Ben Craven – Approximate Calculations

Ben Craven is the PDE first year tutor at the GSA. He has an incredibly technical mind, is very skilled and has a lot of experience in making things. In first year, we were given a project to design and build a cardboard vehicle capable of a number of tasks. From my vague memory these tasks were to be dropped from a meter and start driving, drive over an obstacle course and drive in a circle whilst filming another object. Ben’s vehicle was a masterpiece and had been meticulously designed to perform each task. Despite the fact that we had been working in teams for about a month on the project, Ben’s car outperformed us all.

He spoke to us yesterday about the importance of approximate calculations. Approximate calculations should be carried out as quick estimations of an idea, in order to learn about the potential feasibility of the concept. People often come out with bold, outlandish ideas about proper practice or world-changing concepts, but with a quick, approximate calculation you can quickly have a rough idea of whether it could actually be legitimate.

We were each given an example of an approximate calculation to work through. I had to calculate the feasibility of running the Airbus A380 completely from biomass. After a series of fairly simple calculations I determined that in order to run this plane for 24 hours would require roughly 330 000kg of fuel a day, which related to the harvested biomass energy content of 1 square kilometre of plantation. Taking into account the time that this plantation would have taken to grow and the fact that this is just one plane running for a day, quickly disproves this project as being viable. One person’s approximate calculations might be different from another’s as you are required to perform quick estimations, however you can get a figure that is likely to be in the same ball-park.

For a recent project at the university, I had been looking at the likelihood of saving money whilst installing a digital system to reduce paper waste for the Ardrossan Harbour in North Ayrshire. I performed a quick approximate calculation to estimate how much paper they use, and how much this would cost compared to installing a digital system to make sure it was worth investing time into the idea. Only after calculating that it would be beneficial did I perform more detailed calculations to better predict the situation.

Making these approximations is a skill and one that I think is underused. As a designer it can be an essential tool to use at the start of a project – potentially saving wasted time and effort on a concept that was fundamentally flawed at the start.