Observations on Positions: Monkey X-Rays and Ejection Seat Testing

The telephone conversation with Mike started, "Cliff, they're having problems with the mathematics for their monkey x-rays, and I told them they need a Photogrammetrist; are you interested?" I subsequently paid a visit to the U.S. Naval BioDynamics Laboratories (NBDL) in New Orleans; much to my amazement, Mike was not exaggerating! Although now closed for more than a decade, I became involved in some pretty exotic medical and close-range photogrammetric applications. "Mike" is Michael E. Pittman, a now-retired Physics Professor at the University of New Orleans. When I started with NBDL, they were just finishing up with a couple decades of the primate phase of their research and were going into human testing at "flank speed." The place was staffed with about 25% civilian scientists, technicians, and clerical workers, but was comprised mostly of enlisted Naval personnel who were the Human Research Volunteers or "lab rats," and some Naval medical officers and Naval flight surgeons. A few days later, I was amazed to see a female Army officer walking down the hall. Seems that only the Army has veterinarians, and that's who was supervising the care and health of the monkeys.

No Foolish Monkey

I was told that years ago, when they first started testing with the monkeys, they suited up one monkey, gave him a banana, and held his hand as they walked through the maze of corridors until they got to the horizontal accelerator. Contentedly munching on his banana, he allowed them to seat him into the chair, strap him in, and after the banana was finished, he gave them the banana peel. "Five, four, three, two, one, … WHOOSH!" Some moments later, they unstrapped the surprised but unhurt monkey, gave him another banana, and walked him back to his quarters. After a week of medical testing to verify that the monkey was unharmed, his "rotation" came up again and he was suited up and walked to the horizontal accelerator, banana in hand. As the story goes, when they turned that last corner and the monkey saw the horizontal accelerator, there was no power on Earth that was going to get that monkey into that chair again! Subsequent to that first experience, all the monkeys were then administered a "happy pill" to sedate them prior to the testing.

The only creatures that NBDL scientists discovered that would willingly submit to repeated ejection seat testing in a horizontal or vertical accelerator were U.S. Navy sailors! Those USMC Veteran readers of my column will probably concur in that scientific fact … The Army vet and her patients (all unharmed), were later transferred to the Center for Disease Control in Atlanta, Georgia upon conclusion of the NBDL animal testing (~1995).

The major cause of significant medical injury in sudden impacts and in ejection seat deployments has been damage to the cervical spine, specifically between "T-1," the first thoracic vertebral element (to which the collar bone is attached), and the occipital condyles, where the spine attaches to the skull. NBDL testing over three decades has been the primary source of medical data for the manufacture of mannequins used in high-speed medical impact testing by military agencies worldwide—as well as by automobile research laboratories. Remember seeing the black and white high-speed photos of a man's face during a rocket sled run with the extreme deformation of the skin on his face? That's Colonel John Paul Stapp, then a USAF Flight Surgeon that started this kind of research. Each year there is a Stapp Conference for researchers from all over the world who gather to present papers. On one rocket sled run long ago, another Flight Surgeon had to use his thumbs to push the eyeballs of Dr. Stapp back into the sockets! Dr. Stapp would not let anyone else participate in any experiments until he had found the limits with his own body. He was a frequent visitor to NBDL and he was treated with reverence and awe. A colleague of COL. Stapp was Dr. Channing L. Ewing, the found-er of NBDL and member of the Snell Memorial Foundation (crash helmet testing).

New System

To observe and quantify these (very) ephemeral phenomena of motion, it requires high-speed photography, stereoscopic x-rays, precise optical tooling surveys, and photogrammetry. The original system that had been "designed" by a mechanical engineer in the 1970s was not a rigorous photogrammetric solution, but rather based on contrivances that resulted in a "unique" solution. The engineer chose to "re-invent" the wheel. There were no check measurements designed into the equations, and any slight deviation from the rigid design procedures resulted in the equations being unsolvable. A new x-ray instrument was installed to replace the original one, and with that change the original math shut down the entire lab.

After an initial evaluation of the legacy software code, I concluded that it would be easier to set up a new, rigorous phototriangulation system than to attempt a "fix" for the existing mess. The Chief Scientist, Dr. Marc Weiss asked about what kind of accuracy was going to be achieved with a new approach, and I explained that a software package that computed the Geometric Dilution of Precision (GDOP) would automatically compute that for each point in each solution. Dr. Weiss enthusiastically approved our proposal. We decided to use the General Integrated ANalytical Triangulation (GIANT) program that was in the public domain and available for the cost of a tape copy ($30) from the National Ocean Survey. GIANT was originally written for the IBM 360 mainframe computer in the 1960s as a test for a new sparse matrix inversion algorithm, "autoray," proposed for classified military use.

Later converted and expanded for general photo-grammetric applications, I had used it in the early 1970s for ordinary aerial phototriangulation and mapping. The NOS version had been ported for a VAX computer, and had some "special" calls peculiar to the VAX Fortran compiler as well as some convoluted code that was nearly indecipherable. Nevertheless, Mike and I figured it out and got it running on both a PC as well as on a Unix machine at NBDL. The next problem to face was that GIANT is an extremely powerful program, but it historically took a photogrammetrist to get the thing to work. We had to establish a series of design parameters with integrated instruments so that the existing Lab Technicians at NBDL would be able to operate the system without the need for Mike and I to be present. The first thing we needed to do for the monkey x-rays as well as HRV x-rays was to develop a system to use stereoscopic x-rays for the GIANT system to triangulate.

The primary objective of the HRV tests was to precisely measure the movement of the head and neck with respect to T-1, the first thoracic vertebral element. If a pilot "punches out" of a jet fighter, will he survive? What happens with different helmets, goggles, night vision contraptions, etc.? The plane may crash, but the whole idea is for the pilot to survive in order to fly another day! The Horizontal and Vertical Accelerators had special seats designed to firmly hold the body while allowing the head and neck to be unconstrained. Therefore, we needed a special chair that would be transparent to x-rays but still maintained that same geometry. Such a chair was approved for the HRVs, but the lab did not make one for the animals since they decided to finish with monkey testing.

The machine shop was delighted with the assignment. They designed the seat, they started the fabrication, and I often went to the shop to watch the work. Since I did not ask questions, I did not change details, and I just watched; the machinists tolerated my presence. On completion, we had an HRV assigned to us to use for x-ray testing, and after a day or so we had exposure brackets established as well as rotation angles, base/distance ratios set, etc. The HRV's teeth did not glow in the dark when we finished the tests. After showing stereo x-rays to Dr. Weiss and to the scientific staff, I invited the machinists in to view. From that day on, I was welcomed in the machine shop (other scientists were always chased out), and I was often invited for lunch and to an occasional barbeque in their parking lot. They were good cooks, too!

Images courtesy: U.S. Navy


About the Author

Cliff Mugnier is a Board Certified Photo-grammetrist and Mapping Scientist (GIS/LIS) and teaches Surveying, Geodesy, and Photo-grammetry at Louisiana State University. He is also a contributing writer for the magazine.

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