Challenge 3: Spring-Powered Vehicle Design

Introduction

The concept of spring-powered vehicles has been around for centuries – Leonardo Da Vinci conceived one (below), for instance – and continues to represent an intriguing design challenge.

Your task, working via the internet in a virtual learning environment (VLE) with all the other members of your team and with an assigned member of the Cambridge University Engineering Department (CUED) acting as a mentor, is to design/draw such a vehicle to meet the requirements specified below, using the computer-aided design (CAD) package specified. You and your team will then come to Cambridge for a day to build and test your design with the components/materials supplied/made by the CUED workshops to your specifications.

Design Requirements

Your vehicle must be manufactured entirely from materials in the specified Kit List.

It must be powered using only 2 of the springs provided. A sample of the spring will be sent out to each participant in your introductory pack of information.

Designs will be tested against several performance criteria:

• Speed over a fixed (10 m) distance
• Distance travelled on a horizontal surface
• Distance travelled up an inclined slope
• Accuracy of travel in a straight line (5 m in length)

Parts may not be removed or added between tests, but you will be allowed to change gear ratios, for instance, between tests using appropriate switches.

Getting Started

We have assembled a range of support materials in the VLE to help your team undertake this challenge. The amount of information may seem overwhelming at first. Therefore we would suggest that you focus initially on learning about Project Management and the Engineering Design Process.

There are several aspects of the design you will then need to consider including:

• a winding mechanism to store energy in the spring
• the chassis of your vehicle
• its wheelbase (number and layout of wheels)
• its drive-train (how to drive the wheels using the spring, and which wheels to drive)
• whether to include a gearing system of some sort and whether this should be switchable
• how to minimise friction (important for all aspects of the challenge)
• how to ensure good traction
• the distribution of weight in your vehicle (important for traction and for the hill-climb)

The document Practical Guidelines for Mechanical Design and Manufacture may well prove a source of useful advice on basic mechanical design.

We have also provided a range of information to support the detailed design of your vehicle. Real-world engineering project teams are usually multidisciplinary with engineers with different areas of expertise (Mechanical Engineers, Structural Engineers etc.) contributing to the design process. Rather than expecting every member of your team to take in all the information provided, you may find it more effective to allocate responsibility for different aspects of your design to individual team members.

The materials and standard components you have to work with are detailed in the Kit List.

Submission of Drawings

As part of this challenge your team has to produce manufacturing drawings for your design using the CAD package provided. These drawings have to be submitted to us by 15 December 2006 accompanied by a short document explaining how your design is intended to work to help us interpret the drawings.

We will provide feedback on your design by 5 January 2007. You will then have the opportunity to modify your design in the light of this feedback. Final CAD drawings for your design have to be submitted by 12 January 2007.

Manufacture of Components

Using the drawings you have submitted our technicians will manufacture the metal components in your design in our workshops. Alternatively, if you have access to suitable workshop facilities at school/college or at home, you can opt to manufacture some or all of these components yourself. If you do opt to make components yourself, please remember to bring them with you when you come to Cambridge for the finale.

Finale

In the finale of this challenge you will come to CUED on 27 January 2007 to meet the rest of your team and your mentor face-to-face, to assemble and fine-tune your design, and then formally test it. The provisional timetable for the day is:

10.00 Arrival and registration

10.15 Teams assemble, test and fine-tune designs

13.15 Lunch break

14.00 Tinkering time

15.30 Formal tests of each design

17.00 Participants depart

Post-mortem

After the finales we will assess your designs through discussion (to which all can contribute) in the VLE. The aspects of the designs to be considered will include ingenuity, aesthetics, factors contributing to success or failure on each test, and scalability of the design.

Summary of Challenge Calendar

24 October 2006 Teams announced, challenge starts

15 December 2006 Deadline for submitting initial design drawings

5 January 2007 Feedback on designs

12 January 2007 Deadline for submission of final design drawings

27 January 2007 Challenge Finale in Cambridge