Aerobody - Production Process

Working with composites is all about using the correct process. Without the proper tools, techniques and materials, outcomes can be disastrous. With MSXI, the process required about 90% of the car to be created in a single layup. This process let to a poor outcome in which composites separated and the structural integrity of the vehicle was compromised. 

A note about panels

Similar to the body of most production cars, MSXII's aerobody will be modular and be made up of a number of different panels. There are several benefits to this: 

• If a pannel is damaged, we can easily manufacture a replacement. 
• Strategically positioned panels will be removable, allowing easy access to critical mechanisms such as steering and suspension inside the car
• There is very little financial risk in each layup: if one goes poorly, it will not set back the project significantly
• Easier panels can be created first, leaving the more difficult panels for later once the aerobody team has had more practice with composite work

The Process

Sketching

Sketching is fundamentally important the the look and feel of the overall car. All automotive manufacturers begin the design of the bodywork with sketching and artists interpretations. The following video offers a glimpse of part of BMW's design process: "The first contact that the designer has with the project is the piece of paper and a pencil”.

Another benefit of sketching is it allows you to iterate much faster. Digital surface modelling is a very time intensive process when done properly whereas multiple sketches can be created in a faction of the time. 

Surface Modeling

We will be using Rhino to model the surface of the aerobody. Rhino has a number of powerful surface modelling tools and is far superior to Solidworks for this type of modeling. 

Full Sized Model

Once, we have designed the aerrbody in CAD, we will then obtain full sized models of the car body. These will likely either be made of foam or MDF. More complex curves will be made using a CNC machine while less complex geometry can be made by hand. The surface finish of the model is very important because any imperfections on the model will end up on the final body panels. 

Fibreglass Mould

The next step is to create a fibreglass mould or tool of the body panel. This is done by first applying a coat of mould release to the model. Then tooling gelcoat is applied followed by several layers of fibreglass and resin. The result is a fibreglass mould into which you can do a carbon fibre layup. 

Final Layup

The final carbon fibre layup is complex and there are numerous ways to do it (infusion layup, wet layup, etc.). This step will always require the use of vacuum bagging. A process where a plastic bag is wrapped around a the mould and all the air is sucked out; thus applying pressure to the carbon fibre and transferring all the detail of the mould to the final part. 

There is an excellent video series on youtube that shows the entire process of making a fibreglass mould, followed by layups inside that mould: