Fall 2008 Issue

Tulsa (OK) Technology Center’s Innovative Approach to Training Future Engineers

This past spring KE5URH and his students at the

Tulsa Technology Center designed and built

balloon sats for launch by Oklahoma State

University’s ASTRO balloon-launch program.

Here he discusses his technical and
development journey from development of

the balloon sats to their launch.

By Doug Benton, KE5URH

Photo 3. OSU Professor Dr. Andy Arena surrounded by student assistants inflating the sounding balloon.

Over the past few years there has much concern has been voiced over the dwindling number of engineers and high-tech technicians in this country. Many of us believe that the roots of this dilemma are found at the high school level. Whether it is because of a lack in preparation or a lack of interest, our young adults are not competing in the engineering curriculums at our country’s major research universities.

Various national initiatives have been under way for the past two decades to recruit and develop aspiring young pre-engineers at the high school level, with the hope of refreshing our aging high-tech work force. Recently, these initiatives are being taken more seriously due to increased indications that the United States is losing its role as the world’s leader in innovation and technology. Here in Tulsa, Oklahoma, bridges are being built to span the academic gap between our teenage talent and our engineering colleges.

Under the mentorship of Professor Andy Arena, KE5CAB, and PhD candidate Joe Conner, W2OSU, both of Oklahoma State University (OSU), as well as Mr. Harry Mueller, KC5TRB, of Oklahoma Research Balloons, Tulsa Technology Center’s “Introduction to Aerospace Engineering” class built payloads to fly on OSU’s ASTRO-08 balloon-sat mission, which was successfully flown on February 22, 2008.

The mission objective was to carry student payloads and experiments to the near-space altitude of 100,000 feet MSL, to track and recover the payloads, and then to download and process the data. Student payloads consisted of cameras and temperature data-acquisition equipment. The experimental payloads, built by Joe Conner, consisted of two video cameras, with a third experiment to test a Dual-Tone Multi-Frequency (DTMF) activated cut-down device. This article will focus primarily on the educational aspects of this project, from the perspective of the Tulsa Tech students and their instructor, your author.
Because this type of course work and activity is new in Oklahoma at the high school level, many technological and logistical details needed to be ironed out. All the normal challenges associated with a start-up program were encountered this year. For this mission, I, the instructor, and the students set modest goals. Many lessons were learned through trial and error, and as wisdom would dictate, we learned far more through our failures than we ever could have if everything worked the right first time.

The class objectives for the payloads were to develop reliable and inexpensive technologies for: (1) photographing the Earth at near-space altitudes; (2) gathering atmospheric data; and (3) processing Automatic Position Reporting System (APRS) packets and tracking the payload. Objectives 1 and 2 were reasonably successful, while objective 3 needs further development within the Tulsa Tech class.

Camera Circuit

Based on feedback from multiple sources, we chose the adjustable Interval Timer kit, manufactured by Velleman, to trigger an Aiptek PocketCam on a 20- to 30-second cycle. We found the timer kits easy to assemble, convenient for school purchasing, and inexpensive. At room temperatures the 12-volt kits worked fine. However, we had problems with our kits when they were exposed to even moderate drops in temperature. Specifically, while at room temperature the timer kit was set for a 1-second pulse and a 30-second pause. Then after the temperature dropped to around zero degrees Celsius, the pulse would extend to over 2 minutes with the pause remaining at the original 30 seconds. This drastic increase in the cycle time would, in turn, cause the cameras to go into sleep mode prematurely and cause battery life to decrease.A fix was incorporated by placing a transistor on the output pin of the 555 timing chip to drive the relay (see figure 1). With this change in place, the timer kit functioned properly at and below zero degrees Celsius. I observed this modified circuit working fine for over an hour in a freezer without insulation or supplemental heat. Next year’s class will use a different, smaller timing circuit. A transistor will be used to switch the camera’s trigger, as opposed to a relay switching the camera’s trigger.

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