Spring Car Prototyping

What is it?
A mechanical concept car powered solely by a tension-spring-based energy system (MESU), built for a rigorous university design challenge. The mission? Design, prototype, and test a vehicle that can travel at least 10 feet using zero electronics, under strict engineering constraints.

Project Planning & Constraints
This wasn’t just a fun build — it was a controlled engineering exercise with hard limits on size, cost, materials, and function. Every aspect was documented, reviewed, and tracked:

$30 prototype budget with an additional $15 post-testing
Mandatory use of shop-approved materials only
Must fit inside a 30” x 30” x 30” box
At least one machined component required
Final demo date locked to April 2019, no extensions
Functional requirements like locking, storing, and triggering the MESU

We developed four conceptual designs, evaluated them with a weighted decision matrix, and selected a winner based on energy efficiency, manufacturability, and cost. Weekly milestones were set, with deliverables reviewed at each phase (concept, CAD, prototype, testing, improvement).

The Design
Our final build used:

A dual-rack gear system to switch between distance and speed modes
A laser-cut high-density fibreboard frame
Carbon steel rods and a manually wound 11" tension spring
Modular racks connected to gearsets that translated linear spring force into rotational motion

Testing & Outcome
The MESU functioned flawlessly when charged — it stored and released energy on command. But the vehicle didn’t move. After analysis, we discovered:

Insufficient torque at the drive wheel
Too much weight concentrated on a single point
High gear ratio causing power loss
Rack friction issues

We outlined a full plan for improvements: reducing gear ratios, distributing weight with thicker dual wheels, and increasing torque with stronger springs.

What I Learned
This project wasn’t just about building something cool — it was about learning how real engineering works: planning under constraints, working within deadlines, budgeting materials, and iterating based on testing data. Every change required documentation and tradeoff analysis. I walked away with a much deeper respect for mechanical system design, prototyping discipline, and project lifecycle management.