DOT GRANT

My name is Charles Steven David (pronounced Da-veed). Because I have several doctorate degrees, I insist people call me professor. I am presently working on an Electromagnetic Material Mover (EM3) System funded by the Department of Transportation (DOT). The principal of the EM3 is based on the same principal as a multistage coil gun. It consists of a tube, several electromagnetic coils, several coil driver power supplies, and a computer control system. I received the grant after submitting a proposal to the Advanced Alternative Transportation Projects Department of the DOT.

The grant funds the development of a one-tenth scale version of the EM3 system that could if implemented into a full-scale version, significantly decrease the cost of moving material from one urban area to another urban area. The grant covers both the material cost of a demonstration model and the labor to manufacture and test the scale model.

The grant covers a twelve-month period that includes quarterly progress reports, three design reviews, and a final report.

As stated before, the EM3 design concept is based on a coil gun first developed and patented by Norwegian physicist Kristian Birkeland. In 1933, a Texas inventor named Virgil Rigsby developed a stationary coil gun that was powered by a large electrical motor and generator. Unfortunately, it never piqued the interest of any armed forces.

A payload (projectile) is inserted into the transfer tube (barrel); the first of three coils is energized, moving the payload forward; the second coil is then energized, adding additional momentum to the payload; and then the third coil is energized, accelerating the payload to its terminal velocity.

Ideally, 100 percent of the magnetic flux generated by the three coils is delivered to and acts on the payload, but this ideal is not achievable. With a simple air-cored coil, the majority of the magnetic flux is not coupled into the payload because of the magnetic circuit's high reluctance. The uncoupled flux generates a magnetic field that stores energy in the surrounding air. The energy stored in this field returns to the coil electric circuit, which can seriously damage the driver circuits. Therefore, special driver circuits are required to prevent this damage and maximize the field energy delivered to the payload.

Each coil imparts energy to the payload during two phases. This is accomplished by driving the coil with a full sine wave, where the first phase pulls the payload forward as the field builds in strength and the second phase pushes the payload forward as the field collapses. Matching the coil driver circuit to the coils resistance and inductance is critical to optimizing the energy transferred to the payload. The slope of the applied wave, both positive and negative, is also matched (shaped) to the velocity of the projectile to maximize acceleration.

For EM3, there are two sets of three coils. The first set is the Pitcher coils, which accelerate the payload from its origin to its terminal velocity in the manner described above. The second is the Catcher coils, which decelerate the payload at the destination to zero velocity by reversing the sine wave polarity. In both cases, timing the occurrence of the applied waveform is critical to the proper function of both the accelerating coils and the decelerating coils. The velocity of the payload is also a critical parameter, and sensor coils along the transfer tube provide a measurement of the payload velocity and affect the timing of application of the waveform to both Pitcher and Catcher coils.

AN AMAZING EVENT

November 1999, in a laboratory in Grand Prairie, Texas

I remember it was on a Tuesday. I was running some tests, sending a test article from pitcher to catcher, measuring the energy it takes to accelerate the test article, and then measuring the energy it takes to decelerate the test article. I had recently installed a telemetry transmitter into the test article to record the three-axis acceleration as the test article makes the transition from pitcher to catcher.

The telemetry transceiver is installed on the feed side of the transition tube and aligned with the center axis, perpendicular to the plane of pitcher's coils. After powering on the test article's telemetry transmitter and inserting the test article into the transition tube, I set up my PC to record a short section of data and moved the test article forward and backward in the transition tube to make sure it wasn't binding.

The telemetry data indicated that everything was functioning as designed. I turned on Pitcher's and Catcher's power supplies and function generators in preparation for launching the test article. As this was the first test with the telemetry package, I went through the test procedure a second time to make sure everything was set up correctly. Once satisfied that all was correct, I pressed the launch button.

Immediately, the test article disappeared down the transition tube. I then walked around to the catcher end of the transition tube to retrieve the test article, and it wasn't there. It must have jammed inside the transition tube, I thought. I bent over and looked into the tube. To my surprise, it wasn't there either. I then thought that catcher must have failed to stop the test article. It must have exited the transition tube and ended up in the large screened area of polyfoam popcorn packing material I used to stop the test article before it impacts the overhead door. I stirred the polyfoam popcorn with my hands but could not find the test article.

My search was interrupted when someone rang the laboratory doorbell. When I got to the front door, I was surprised to see a young girl, about twelve years old, dressed in a baseball uniform, standing there holding the test article.

"Is this yours?" she asked.

"Where did you find my box?" I replied.

"It suddenly appeared in the outfield while we were practicing, and Coach said I should bring back to you."

"How did you know to bring it here?"

"Coach recognized the name of your company on the box. He said he sometimes parks in front of your office when the parking lot at the ball field is full."

"Can you show me where you found it?"

"Sure," she said as she turned to go.

I followed her away from the front of my building, across the street, down a tree line, and onto a softball field. We walked across the outfield until we reached the outer edge of the infield where she pointed to a skid mark on the clay.

"Right there, at the end of the skid mark," she said.

I thanked her and gave her $5 for her trouble. As I returned to my laboratory, I stopped and examined the overhead door. I expected to see a large hole where the test article had gone through the door. Not a single scratch was visible. I'm totally confused by all that happened. It just didn't make sense that the test article could have exited the tube, flown across the outfield, and come to rest in the infield of the ballpark, a distance of some three hundred meters, without any outward signs of damage. It's just not possible. As Yul Brenner said in the movie The King of Siam, "It's a puzzlement!" I decided to stop all tests with the test article until I can somehow come up with a rational explanation of how this happened. I certainly don't want anyone to get hurt by my testing.

I decided to look at the telemetry data to see if it would...