New Emphasis on Standards and Practices

Everyone reading this blog is involved in some way with mass properties – as an engineer, a technician, a manager, or sales. Every one of us has experience and knowledge that we could pass on to others involved in the mass properties world. Broadly speaking, this knowledge can be broken into two overarching categories – Technical Details and Methodologies.

Throughout its many years, the SAWE has concentrated on the first of these categories, asking mass properties personnel to spread their knowledge of technical details by writing papers, giving presentations, or teaching a class. We still want (and need) our practitioners to do this.

Paradoxically, the influence of the SAWE as an organization has grown while our individual influence has shrunk. Let me try to explain this. Several years ago, the SAWE became a Standards Organization by seeking and achieving recognition by the American National Standards Institute (ANSI). As a result, the society has gained a growing influence in both America and abroad. However, even as the society as a whole has gained recognition for our unique mastery of the science and art of mass properties concepts, our members have experienced erosion of the profession by those who employ mass properties personnel. Primarily this has been a consequence of ever more capable automated capabilities of computer programs. This has created a sense that what we as mass properties professionals can do can be duplicated by computer algorithms. This is not a new phenomenon. Forty years ago, when I was a fresh out of college new mass properties engineer, I heard the head of the mass properties group say, “Eventually, we’ll be able to push a button and the computer will spit out a new airplane design.” Implied in this was that we would not be needed.

I will be the first to admit that much of the calculation duties that were required all those years ago have been supplanted by Computer Aided Design programs, provided that the required parameters have been properly implemented. Calculating weight, CG, and inertias rarely gets performed by today’s mass properties engineers, except perhaps during early conceptual designs. Although this was a large part of my initiation into mass properties, there were many other aspects, including evaluating assembly drawings for completeness and crucially, compatibility. I have lost track of the number of supposedly connectable parts which obviously wouldn’t connect, missing parts, and even parts that shouldn’t be in an assembly and whose presence would preclude operation of the assembly I have found. And these were assemblies that had made it through the Checking group! This was never written down as part of my job description, but are errors I found that had to be corrected before I would accept an assembly into the database. These problems don’t disappear because a computer has calculated some numbers. It still takes a person looking at a project as a whole to find and solve these problems.

Which brings us to the second knowledge transfer category – Methodologies. The SAWE has an obligation to ensure that its members know what is required to perform as mass properties practitioners. The most effective means of performing mass properties tasks is to work through the task in an orderly fashion, so that we can be sure that nothing of importance is inadvertently missed. And the society has found that having a blueprint of what tasks are required is an effective aid. We call these task “blueprints” Standards if the “blueprint” conveys specific technical information that results in a consensus of how that information is presented. An example would be a standardized coordinate system used by a specific industry. How a standardized coordinate system is implemented is not included in the Standard. A Practice is the flip side of the coin regarding Standards – a Practice delineates the accepted means of performing a task. The SAWE designates a Practice as a Recommended Practice, such as SAWE RP A-3, 2016: Mass Properties Control for Space Vehicles. This RP defines what is accepted in industry to ensure that required mass properties tasks are completed and in useable form.

The SAWE has requested that mass properties practitioners consider writing a paper for the conference in Fort Worth in May, 2018 to address specific gaps in our Standards and Practices. Applicable papers do not need to be fully realized Recommended Practices or Standards, but should be utilizable as a framework upon such RPs or Standards could be taken up by our Industry Committees and turned into RPs or Standards (using our standardized templates). Specific areas of interest are delineated on the SAWE web site at https://www.sawe.org/technical/papers/2018Campain (yes “campaign” is misspelled in the URL). Please consider what you can contribute to the SAWE by helping us fill in the gaps in our Standards and Practices, and increase our visibility into Mass Properties Methodology. And if you know of specific Technical Knowledge, we will of course accept Technical papers as well. In either case, if you write a paper for the conference, please submit your abstract at http://www.sawe.org/technical/papers/submittal.

Author: Robert Zimmerman

SAWE Vice President – Technical Director

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