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Chapter 23 Exercises
Note: There are no unique solutions to many of these exercises.
Minimize Design Information Content
KISS (Keep It Simple, Stupid) was coined by the American design engineer Kelly Johnson to
indicate that a military aircraft should be repairable with a limited set of tools under combat
conditions. Johnson wrote it as ‘Keep it Simple Stupid‘ (without the comma) because it was
not meant to imply that an engineer was stupid; just the opposite. A simple solution is better
than a complex one even if the solution looks stupid.
1) A company received a complaint from a customer that she bought their product but the
box it was supposed to be in was empty. The company then installed an x-ray machine on
the assembly line and staffed it with two workers to make sure that no more empty boxes
2) NASA spent $12 million to develop an ink pen that would write in zero gravity and in a
wide range of temperatures. How would you solve this problem using the KISS
3) To test the design ability of an engineering student a professor filled a bathtub with water
and then offered the student a tea spoon, a cup, and a bucket to empty the tub. How
4) Internet web pages are often confusing. Use the internet to find a web page you find too
complex and suggest ways to KISS simplify it.
5) Shakespeare wrote “This life, which had been the tomb of his virtue and of his honour, is
but a walking shadow; a poor player, that struts and frets his hour upon the stage, and
then is heard no more: it is a tale told by an idiot, full of sound and fury, signifying
6) Shakespeare also wrote “Shall I compare thee to a summer‘s day? Thou art more lovely
and more temperate. Rough winds do shake the darling buds of May, and summer’s lease
hath all too short a date. Sometime too hot the eye of heaven shines, and often is his gold
complexion dimmed and every fair from fair sometime declines, by chance, or nature’s
changing course, untrimmed. But thy eternal summer shall not fade nor lose possession
of that fair thou ownest. Nor shall Death brag thou wanderest in his shade, when in
eternal lines to time thou grownst; So long as men can breathe or eyes can see, so long
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lives this, and this gives life to thee.” Use the KISS principle to simplify this message to
Functional Requirement Independence
7) Explain whether or not the steering and speed of a large ship functionally independent?
8) Explain whether or not the steering and speed of a bicycle functionally independent?
9) Is there a component in a system that you think should be functionally dependent on
another component (think safety)?
10) How could you uncouple the water cannon design steering and catapult aiming shown in
Figure 23.2?
11) How could you uncouple the twin boat design move the turn functions shown in Figure
23.3?
Design for Ease of Manufacturability and Robustness
12) What are the seven questions you should ask when designing for ease of manufacture
13) The Boeing 777 uses 3 million parts that come from 500 suppliers around the world.
Explain why this would be an example of ease of manufacturability.
14) What are the three questions you should ask when designing for robustness?
15) End users often use products for things that the designers did not anticipate. How would
you increase the robustness of a ceramic coffee cup so that someone could use it as
hammer?
16) What adjustments can be made to the motor driven moving platform in Example 23.3 to
decrease the cost?
Decision Matrix
17) Develop a decision matrix for the two student designs in Example 23.1 using the
following criterion: 1) It must fit in a 2 ft × 2 ft × 3 ft volume at the start of the
competition; 2) It must carry a target that disables the boat if struck by opponent; 3) the
steering and motion must be independent; 4) it is easy to manufacture.
18) Develop a new decision matrix for Example 23.4 (Table 23.2) by adding “Low cost” to
the list of criteria and change the weighting factors as follows: Drives well – 0.15; Putts
well – 0.20; Loader is robust – 0.15; Easy to transport – 0.05; Easy to manufacture – 0.25;
Low cost – 0.2. Determine your own values for each of the three golf machine concepts.