Final Product

Below is the final 3D-printed model for my project.

Notice Anything Odd?

 The 3D Printer needs to build an interior support structure to apply layers that don't have anything underneath them. This is why the wheelhouses and the roof have plastic underneath them. Otherwise, the filament would just fall to printer bed below.

The support structure is very efficient, to allow for easy removal and to minimize wasted filament.

After pulling the support structure out with pliers, my model was complete.

Hooray!

The surface is full of ridges because the 3D printer cannot replicate the model with complete precision. I would have produced a smoother model by decreasing the layer height. (see previous post on 3D printing)

Sadly, this concludes our journey into the fascinating world of car design. I learned a lot in the past few months, and I'm sure you did too.

The next time you are on the road, I hope you see cars a little bit differently!

PS

To view my project's PowerPoint presentation, please click here.

CAD Model

After lots of trial and error, my surface model is finally complete. Surface models, as the name suggests, are two dimensional -- they have no thickness. To make a 3D printed model of this, I needed to add thickness to it. This was harder than I first expected because different parts of the car intersected each other when extruded outward, producing computer errors. I spent a lot of time correcting these errors to make 3D printing possible.

Here it is!

Preparation for 3D Modeling

Before I start developing my model in 3D, I need to make my initial sketches more precise. There are several key dimensions used in the Computer-Aided Design workflow that need to be identical across the sketches, to avoid any discrepancies. This includes the ground clearance, total height, and belt line height. It is also important that the height, width, and length have the correct proportional relationship, so the 3D printed model is to scale.

After making the necessary adjustments to the sketches, I am now ready for 3D modeling!

Below are the finalized sketches.

Design Considerations

After further reviewing my sketches, there are some design complications that I will have to address.

Firstly, the air intake system on the body side creates an impression on the doors. It is important that the side glass has enough room to drop into the door structure. This means I cannot add too aggressive indentations to the door's exterior surface, because it would push the interior trim inwards, cramping the occupants.

The side glass cut lines are not defined within the door profile. There are also no door cut lines. Fortunately, car doors are flush with the exterior surface, so door profiles will not change the final, 3D printed product. By contrast, side glass is slightly offset from the adjacent door surface, so cut lines are necessary to make changes to this surface.

A two dimensional model is not good at communicating the variation in depth along the vehicle surface, even with sketches from different views. I will have to wait for the 3D modeling to add more detail.

Occupant Packaging

To set up the occupant package, I must establish some key dimensions and position the SAE 95th Percentile Manikin. Before I can do that, I need to keep these factors in mind:

On a high performance car, the front and rear spindles are positioned to provide optimal weight distribution. I cannot change these to accommodate the occupants.

Crush space is behind the driver for a rear engine vehicle, because there are no hard components in front of the driver. Thus, there must be more room than for just the engine behind the driver's seat.

The dimensions below correspond to the diagram.

1. H-Point to Ground: 325 mm

2. Chair Height: 150 mm

3. Back Angle: 28 degrees

4. Forward Vision Angles: 8 degrees up, 5 degrees down

5. Effective Headroom: 955 mm

6. Shoulder Room: 1350 mm

7. Lateral Location: (from center line) 340 mm

Size and Proportions

In this phase of the design process, I will look at some key dimensions of the model, derived from my sketches, and compare them to similar vehicles. This is known as benchmarking.

The Ferrari LaFerrari is a modern rear engine, RWD supercar. I chose this vehicle for comparison because of the similarity in side profile view to my model.

Exterior Dimensions:

LaFerrari

Length: 185.1"

Width: 78.4"

Height: 43.9″

Wheelbase: 104.3″

Front Track: 66.9"

Rear Track: 64.4"

My Model

Length: 181

Width: 72.

Height: 47

Wheelbase: 105.5

Front Track: 65.

Rear Track: 63.

My Model

LaFerrari Front (not mine)

LaFerrari Side View (not mine)

Package Ideation

Before settling on one design, it is important to explore every possibility at the beginning. After the initial ideation phase, it will be too late to introduce different ideas and start from scratch.

There are two ways to complete the ideation phase for cars.

In one method, the exterior design is developed first to inspire the package layout. The package consists of all of the elements driven by function not appearance, such as the engine, fuel tank, wheels, seating, etc.

It is also possible to start by sketching different layouts for the cargo, occupants, tires, and powertrain. Then ,a loose sketch of the body profile will provide a medium to analyze how different package configurations change the exterior proportions.

Either way, the goal is to explore as many options as possible that satisfy the functional objectives.

I will use the latter method in my ideation phase.

For a high performance vehicle, a powerful engine is a necessity. This effectively eliminates the transverse engine layout, because the engine is constrained by the frame rails. I will consider front and rear-mid engine layouts, FWD and RWD, and also electric motors.

At this stage, exact dimensions are not important. The purpose is to evaluate the resulting proportions of each layout and then chose one or two to develop further.

I chose to continue with the mid-rear engine, RWD layout, which will be the focus of the remaining posts.

Next, I will work out the key dimensions and set up comparisons to similar vehicles.