Reflections on T&E, part II: development of test technologies international cooperative test and evaluation - DOD Test and Evaluation

Program Manager, Sept-Oct, 2002 by John F. Gehrig, Frederick D. Mabanta

This article is Part II of an article appearing in the July-August 2002 issue of Program Manager (pp. 56-62). That article, "Reflections on Test and Evaluation," presented the views of authors John E Gehrig, Gary Holloway and George Schroeter on three important aspects of Test and Evaluation: State of the T&E Infrastructure, Lessons Learned in Reengineering Army T&E, and Critical Attributes for a Viable Test Range Complex.

We could not emerge from the experiences and opportunities afforded by our lifelong careers as testers, engineers, and evaluators, without formulating several strong opinions concerning the direction of DoD Test and Evaluation (T&E). In an effort to document several of these opinions and experiences, this article--the second of two entitled "Reflections on Test and Evaluation"--covers two themes we co-authored: Development of Test Technologies and International Cooperative Test and Evaluation.

Development of Test Technologies--Yesterday, Today and Tomorrow

Test technology has become very high-tech, complex, and expensive. No longer can it be developed by individual dedicated test engineers in the "back room," but must be pursued in a systematic way under a structured program that encourages such development and provides the necessary resources. A Test Technology Base Program for the Test and Evaluation community is essential to fulfill future test requirements.

Welcome to Yesterday's Museum of Testing

If there were a Museum of Testing, one could visit that museum and trace the evolution of what we now call Test Technology It wasn't long ago that we were still using strip charts and the term "photogrammetrics"; that is, taking measurements from photographic images was the "biggie" of its time.

Remember cinetheodolites and ballistic cameras? How many remember (or ever knew) the early--really early--days of testing when we started testing some new weapon systems called rockets? We lined up a bunch of soldiers and sailors in a trench, equipped them with a clip-board and pencil, and instructed them to observe a missile firing and record their observations about the flight path and performance.

We quickly got beyond that approach and started using movie cameras, shooting though a wire grid with a clock hung on a corner of the grid within the camera's field of view. The grids were calibrated to provide angular references and the clock provided a time tag so that images from several similar set-ups could be time-correlated to provide position in space data referred to as Time-Space Position Information.

Another museum item might be the pieces of cardboard called Yaw Cards that were placed in the trajectory of a projectile to get some idea of a projectile's stability--was it yawing or tumbling? A clean, round hole indicated that the projectile was flying true (at that point). An elongated hole indicated that the projectile was pitching and/or yawing. What does it mean when one gets an "L" shaped hole? Yes, there were holes like that.

Photographic techniques were also used extensively in ballistic work. The "Streak" or "Smear" camera could capture the image of a projectile in flight to determine if it was flying true--at least at that particular point-if it had shed its sabot, and if it was intact. Two such cameras placed strategically along the trajectory of the projectile could give a measurement of spin. Streak or Smear Cameras ran (streaked) a length of motion picture film along a slit at the focal plane. The speed of the film was regulated (synchronized) to correspond in scale to the velocity of the projectile.

Thus the image of the projectile was "painted" (or "smeared") on the film. One can see how the fond names of Streak or Smear cameras were derived. The "techies" of the day however, officially called them "Syncho-Ballistic Cameras." Improper synchronization of the speed of the film across the slit with the velocity of the projectile yielded an elongated or compressed image. Photogrammetry was used so much in the "yester-years" of testing, that silver recovery from the silver halides of photographic film was a serious consideration.

To be sure, some vestige of photogrammetry and other yester-year test technologies still remains, but much of these [then] very capable but inefficient (by today's standards) technologies, have mostly been replaced. If photo-optics was the mainstay of testing past, then the microprocessor might be considered the mainstay of testing present and future.

The Evolution Continues

The evolution of test technology grew to a large extent, from the innovations of dedicated individuals faced with the need to make some measurement or make it better. Who else for example would think of using Yaw Cards, or of firing a magnetized projectile though two coils of wire spaced a given distance apart to detect time of passage from magnetically induced currents, and thus a measure of projectile velocity.

Or who would think of placing a copper sphere in a cylinder, capping the cylinder with a plunger, and inserting this device in the chamber of a gun to measure peak pressure from the deformation of the copper sphere (an old approach, but this "Copper-Crusher Gage" is still in use today throughout NATO countries). Test technology innovations were also adaptations of technologies developed for other applications. This is now the more common approach since the tester no longer has the time and the tools (such as access to machine shops) to experiment and "tinker."