Week 2: Methodology

I have chosen a controlled experimental method, in which a single independent variable (suspension geometry) is systematically altered while all other variables are held constant. This method was selected because it allows for direct causal comparison between the two suspension systems, minimizing the influence of confounding factors such as driver error, vehicle weight variation, or inconsistent terrain. The use of a 1:10 scale RC platform further strengthens experimental control, as it enables repeatable high-speed trials in a contained environment that would be unsafe and cost-prohibitive at full scale.

Steps

1. CAD Design

   Before any physical fabrication begins, I will design both the Double Wishbone and Trailing Arm suspension systems in Onshape. This step is essential because it allows precise geometric relationships, such as camber angle, suspension travel range, and mounting point alignment, to be verified digitally before committing to a physical build. Designing both systems on the same base also ensures that each shares identical mounting interfaces on the chassis, which is critical for isolating the suspension geometry as the sole variable.

2. Fabrication and Assembly

   Once designs are finalized, components will be printed using high-strength PLA+ filament, with SLA resin or nylon as contingency materials if durability proves insufficient under load. The chassis will be assembled with a telemetry-capable Electronic Speed Controller (ESC), enabling consistent, measurable power output across all trials.

3. Bench Testing and Calibration

   Prior to field testing, each suspension configuration will undergo a standardized Drop Test, in which the chassis is released from a fixed height onto a flat surface. The rate of oscillation decay will be measured using the onboard MPU6050 accelerometer to calculate the Damping Ratio of each setup. This calibration step ensures that both configurations operate within the same damping range (ideally the industry-standard “critically damped” zone) before any terrain trials begin. Skipping this step risks comparing a well-tuned suspension against a poorly tuned one, which would compromise the validity of subsequent field data.

4. Controlled Field Trials

   Each suspension type will complete 10 timed trials on asphalt and 10 on gravel, for a total of 40 runs. The track layout will remain identical across all trials, and vehicle speed will be regulated through consistent ESC throttle settings. The MPU6050 accelerometer will log lateral G-force data continuously throughout each run. Ten trials per surface per configuration was chosen to produce a statistically meaningful sample size, allowing for the identification of consistent patterns while accounting for natural run-to-run variation.

5. Data Analysis and Comparison

   Following field testing, accelerometer data will be compiled and analyzed to compare lateral acceleration variance, oscillation frequency, and overall stability metrics between the two systems across both terrains. High-speed video footage will supplement the sensor data by providing visual confirmation of suspension travel and tire-contact behavior during cornering and surface transitions. Results will be presented as comparative graphs, allowing direct visual identification of performance differences between geometries and across terrain types.

Limitations

1. Material Constraints of 3D-Printed Components

   PLA+ and even SLA resin are fundamentally different materials from the aluminum, steel, or carbon fiber used in real suspension systems. Under repeated high-impact loading, printed parts may flex, fatigue, or fracture in ways that genuine suspension components would not. This means that some of the performance data may reflect material behavior as much as geometric design. While switching to stronger filament types mitigates this risk, it cannot eliminate it, and the findings should be interpreted with this constraint in mind.

2. Designer Inexperience and Geometric Accuracy

   As a student rather than a professional mechanical engineer, my CAD designs and fabricated components may not perfectly replicate the true geometric properties of Double Wishbone and Trailing Arm systems as they are implemented in real automotive engineering. Subtle inaccuracies in joint placement, camber angles, or suspension travel range could mean that any observed performance differences partially reflect the quality of my designs rather than the inherent characteristics of the suspension geometries themselves. This limits the degree to which conclusions can be generalized beyond this specific prototype, and future iterations of this project would benefit from design review by an experienced engineer.