Amateur Aerodynamics

Weight is a problem for electric vehicles: almost invariably, EVs are heavier than their ICE counterparts of similar size. For example, the Chevrolet Blazer EV weighs 5163 lb in its lightest trim, 1245 lb more than the lightest ICE Blazer. Weight increases force and power required at speed, hinders maneuverability and negatively impacts driving dynamics, increases particulate matter pollution ( from both tires and brake pads ), and reduces efficiency —not to mention requiring greater energy inputs to construct commensurate with the greater mass of material needed to build the heavier car in the first place. This Hyundai Ioniq 6 weighs 1000 lb more than the Sonata, despite the two having similar dimensions. The reason EVs are heavy is because they require large batteries to have acceptable range; however, while total range increases with battery size, efficiency (range per unit of energy) goes down as more weight is added by the increased battery size, which requires more energy per u...

Measuring Changes in Drag (NB: I conducted this testing early last summer but, due to a busy fall semester, have only got around to posting it now...). Before I construct a full tail mockup, I decided it would be worth my while to do some additional testing on the partial buck I already have: There are a few reasons I decided this. First, I want to know how much this board and side plates—effectively, a large spoiler at this point—reduce the drag of the car. Second, I want to check my process for measuring changes in aerodynamic drag on this car, which has an electronically controlled throttle that does not allow for throttle-stop testing.   I’ll elaborate on that process below. As far as the first reason: not only will measuring the drag change at this point allow me to better predict the change from a full tail, but if this spoiler turns out to reduce drag as much as my design requirement, then I can stop here (if I want; I won’t, because I want to go through the process of ...

Systems engineering has a long history despite not becoming a formalized discipline until after World War 2. What is systems engineering? Basically, it is the overarching management of large or complex design projects: identification of customer needs and market, development of requirements, control of subsystems and integration, etc. For example, how is a modern airliner built? First, a preliminary design study is completed, often lasting a few years, before requirements are finalized and the basic design of the vehicle is established; then, detailed design work can begin, which usually takes several years to complete. Finally, verification and certification testing are completed, after which the vehicle can be released. All these processes are overseen by systems engineers. The evolution of automotive systems engineering in one picture. As time goes on, the product is more technically complex and requires more rigorous control of various inputs in the design process. Similarity Analy...