Using a catapult in lean six sigma training (optimization)

Use of lean six sigma training catapult in classroom sessions has many benefits, including hands-on experience to improve a process response; i.e., projection shots of the catapult.

Nearly every good classroom course in Lean Six Sigma uses a catapult in their training.  A catapult provides a tool/process that the students understand that will provide data for analysis.  The data has random variation and non-random variation.  It can be used for statistical process control (SPC), hypothesis testing (t and f tests), ANOVA, Regression, design of experiments and much more.  It is a great tool for lean six sigma training and many other courses.

I believe that I worked with the first person to use a catapult in statistical training back at Texas Instruments in the mid 80’s.  One of the developers of the Stat-a-pult (a registered name) saw it in use and asked to use it in their training and soon came out with the Stat-a-pult for sale to others.

Since many of us have used the catapult in training, I have decided to write about my lessons learned from many years of use and observation.  If you did not realize it, there are two primary designs for training catapults.  One is larger and has aluminum pins for stopping the arm and uses large rubber bands.  This model seems to have less variability in its output and has enough force to toss many styles of balls.  The other style is a bit smaller, it uses a string to set the stop angle, and it uses standard rubber bands.  This style seems to have slightly more variability than the other model, but I am think it is due to the higher number of adjustments that are available.  But both models have very similar performance and common key factors to improve performance.

Now for advice on the use of a catapult; There are only two things that affect the distance traveled: the velocity and the angle that it leaves the arm.  That is it, nothing more (with respect to the catapult) You might think that the ball impacts the distance and it does, in that a heavier ball slows the arm down.  I have seen that balls of similar diameters change distance by weight and nothing else.  You would think a whiffle ball with holes would be different from a solid ball, but it does not.  I believe that the low velocities and short travel times do not give time for the air resistance change to impact the distance in a measurable distance.

There are many factors that can be changed in a catapult and in how it is executed, but they only impact either the velocity or angle.  Think about it, once it leaves the catapult it is just physics that determines the distance traveled.

Factors that affect the angle of departure: Stop angle

Factors that affect the velocity of departure: everything else.

If you think of it this way, it changes how you address the factors in your testing.  Now I am only talking about the average distance affect, not the variation in the distances.  That is a different issue.

My list of causes that have shown to affect the average shot distance of the Lean Six Sigma training catapult:

  1. Start angle (farther back, longer distance), number of rubber bands (more force, more distance)
  2. arm length (longer arm, more ball velocity at for the same arm velocity)
  3. ball weight (slightly heavier ball, slightly shorter distance  due to slower arm velocity from mass increase)
  4. rubber band attachment event (if you wrap the rubber band around a fulcrum between the attachment points, the amount of band between the arm and the bend point can change the force applied to the arm , changing the velocity)
  5. pausing before release (if you draw back the arm and then pause for 2-5 seconds the rubber band relaxes and becomes more consistent in its force, this is a bigger issue than most people realize)
  6. release method – centering z(if it is not centered there is additional friction on the arm causing it to slow)
  7. release method – drag (if the release is not clean  and you drag a finger on the arm it will slow down the arm)
  8. release – pull back force (if you pull down just prior to release, you cause a bend in the arm and the stop to give slightly higher velocity and longer distance)

All of this is true, and I have tried them all.  When I started my position at my prior employer there was a slow period in the first few months I  was working so I took two days in a reserved conference room to throw hundreds of balls so that I could truly understand the catapult in preparation for training.  There was multiple DOEs, regressions, ANOVAs, and such.  I tested my theories and tried to develop a predictive model for the catapult that spanned most of the range of the parameters.  I had one that worked OK, but I found too much difference between catapults to have it useful.  I found that there is friction in the primary spindle and apparent surface finish issues with the arm and the sides that hold the spindle.  So it was fun, but not much use.  Although it paid the same as real work, and I did publish an internal white paper on the usage in training for our clients.  And it was fun!

Using a Clickable DMAIC Roadmap with a Lean Six Sigma Training Catapult

In our Lean Six Sigma classroom training, we use the original training catapult design; i.e., not a statapult.  There are many advantages to using the original catapult design in classroom training.



In this training, we also use an Integrated Enterprise Excellence (IEE) Lean Six Sigma CLICKABLE Lean Six Sigma Define-Measure-Analyze-Improve-Control (DMAIC) Roadmap. This DMAIC roadmap has an addition measure phase drill down, which among other things, provides a structure for naturally integrating Lean and Six Sigma tools so the right tool is used at the right time to improve a process-output metric.


Lean Six Sigma 2.0 DMAIC roadmap that is clickable


In our Lean Six Sigma training, details for each of these DMAIC steps is referenced using our book, Integrated Enterprise Excellence Volume III: Improvement Project Execution , which is structurally included in the training; i.e., trainees get much more than a deck of slides to reference in the future.

catapult training tool using our Lean Six Sigma book



Application of Catapult Process Improvement Training Methodology to an Organization’s Big Picture

When creating a Lean Six Sigma deployment and associated training, it is important to keep in mind that organizational improvement efforts should give focus to benefiting the organization’s big picture financially. That is what is accomplished with the 9-step Integrated Enterprise Excellence (IEE) business management system, which among other things provides direction on the selection of DMAIC projects that will benefit the organization’s overall financials.

How to benefit from the IEE system in operations management with its Enterprise Performance Reporting System (EPRS) software (which provides automatically-updated, predictive scorecard reporting with a process improvement system so the big picture benefits) is described in:



business management system meeting


Contact Us through an e-mail or telephone call to set up a time for a discussion on how your organization might gain much from an Integrated Enterprise Excellence Business Process Management system. Or, a Zoom meeting can be schedule directly:

E-mail ([email protected]) or call us (+1.512.918.0280), if you encounter difficulties setting up a Zoom session directly or want to schedule another time that is not available in the Zoom-meeting calendar.

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