Problem Identification: The first step in the Design Life Cycle is determining what the problem is ─ or what the customer needs. Engineers are problem solvers at heart. Their job is to design and build something better than before. Sometimes this involves modifying an old idea and sometimes it means starting from scratch with a whole new idea. At the beginning of a project, an engineer starts out with a list of requirements, or things that a product must do. For a rocket, requirements might include how fast it must be, how safe it has to be, how much it can cost, how much it can weigh, or when does it have to be completed. The requirements define what needs to be done to accomplish the project, or job. It is the engineer's job to come up with a solution to the problem that meets all the requirements.

Forming Ideas: The next step in the engineering design process is an idea: "I wonder if…" The idea phase is where a group of engineers will brainstorm a bunch of ideas that might work as a solution to a problem. When these ideas are combined, a rough idea for a solution is complete.

Feasibility: Engineers must then decide if the solution they came up with is feasible. Feasibility is not a question of "is it possible" (since little is impossible in today's high-tech, fast-changing world), but the questions are: can we afford it, is it safe, and is it the right thing to do? Projects are judged for feasibility by a panel of reviewers with strengths and expertise in science, engineering and project management.

Conceptual Design: Once a project is deemed to be feasible, the next step is the conceptual design. The primary questions that are answered during the conceptual design are:

• What is the general configuration of the structure to be built?
• What major trade studies should be made (i.e., hardware, software, materials)?
• What is it going to cost (calculated estimation)?
• How long will it take (calculated estimation)?

The design that comes out of the conceptual design phase is not the final design, but during this phase many of the important questions about what the final design will look like are answered.

Preliminary Design: If the conceptual design is acceptable, the team can move on to the preliminary design. Actions for the preliminary design are:

• Perform trade studies (decide on best components, materials, etc.).
• Create initial detailed designs.
• Create a detailed schedule and cost plan.
• Further develop concepts with the goal of reducing risk.
• Establish sufficient margins of safety.

Detailed Design: The detailed design phase is where the detailed design is agreed upon and finalized. The customer must be happy and agree with the design, budget and schedule before anything can be built.

Build and Test: This is the point where the manufacturing of hardware begins. (Presumably) all design details are complete and every part of the design is ready to proceed into reality. As part of this work, engineering models are often constructed for performance checks and tests. These tests are done with significant margins added to each of the tests - making them more extreme than anticipated during the mission. Any failures or weaknesses in the design must be corrected (back to conceptual or preliminary design) and retested to prove the product will fulfill its requirements.

Figure 1. The engineering design process. click for copyright

Delivery of Product: Finally, after much hard ─ yet very satisfying ─ work, the product is then delivered or sold to the customer along with documentation of all tests and operations to prove that the design works.

Design, testing and re-design are integral parts of engineering that improves the final product. Nothing is ever just right the first time. Mistakes are inevitably made, but engineers learn from their mistakes, which are used to improve the product during redesigns. Even a design that works can be improved ─ maybe it can be produced even more inexpensively, maybe it can last longer, maybe it can be faster, etc.

Attached are some examples of rockets and their builders. Note that some of the rockets have numbers after their name: a number that is increased each time they re-design and improve the rocket!

Prediction: Have the students make a prediction on the following question:

• How many people think they can build a perfect rocket on the first try? (Tally student answers on the board. Tell the students that they will learn whether or not most engineers can design something right on the first try today.)

Discussion Question: Solicit, integrate and summarize student responses.

• When a company wants to build a rocket, does someone just give them the materials for free? (Answer: No, cost is a very important consideration in an engineering project. Before a group of engineers receives money to build a rocket, they must have a detailed design that outlines how the rocket will perform, how much it will cost and how long it will take to build.)

Reasonable Question or NOT? Spacewoman Tess, Spaceman Rohan and their daughter Maya are incredibly busy planning their trips. They have given you, as their engineering team, 5 minutes to ask them a few questions regarding their rocket design. Have the students as a class vote on whether or not the following questions are reasonable questions to ask regarding designing Spacewoman Tess' rocket:

• What is the purpose of the rocket?
• How much money do we have to build the rocket?
• Should the rocket be pretty or ugly?
• How much time do we have to design and build the rocket?
• When do you need the rocket?
• How long will you need to be in space?
• What are the satellites for?
• When will the satellites need to be in orbit?
• What color should the rocket be?

Brainstorming: In small groups, have the students engage in open discussion. Remind students that in brainstorming, no idea or suggestion is "silly." All ideas should be respectfully heard. Encourage wild ideas and discourage criticism of ideas. Ask the students:

• What are some steps you think engineers have to take to design a rocket? (Prompts: Do they have to think of ideas? Gather materials? Build a model? What else?)
• What are some trade-offs an engineer might have to consider when designing a rocket? (Possible answers include: safety, cost, materials, height of launch, weight, etc.)

Figure 2. Sample design flowchart click for copyright

Design Flowchart: Have the students create a list and description of the steps in an official engineering project. Also, have them produce these steps in a flowchart (see Figure 2). Ask them what happens when there is some weakness or problems during the build and test phase? What would you do and back to which step does that take you?

• Problem Identification
• Forming Ideas
• Feasibility Study
• Conceptual Design
• Preliminary Design
• Final Design
• Build and Test
• Re-Engineering
• Delivery of Product