ESS 472, Summer 07
High Altitude Research
Instructor: Michael McCarthy
Office: JHN 261
Office Hours: arrange
1. For science instrumentation, we prepared a 2-channel gamma ray detector and an electric field instrument. For engineering systems, we had three 3-axis accelerometers and an autonomous system for payload separation. A 3-axis aspect magnetometer, the GPS system, a computer controlled backup deploy system, and flight code to read and store instrument data were not fully operational at flight time, and did not fly. An in-flight motor ignition system was assembled and underwent preliminary testing, but also did not fly.
2. SUCCESSES! We launched two rockets on 13Oct07 from Mansfield, WA. The image below shows the two flights, with the yellow rocket carrying the spectrometer and electric field instrument to altitude. Both instruments sustained minor mechanical damage, but were functional post-flight.
3. FAILURES! At the launch site, we had a premature igniter firing during a ground test of the pressure-sensing chute deployment system. Its microcontroller chip had not been properly installed in its socket, and we firmly seated it, hoping that this would solve the problem. On the launch rail, the same unit again ignited the chute deployment charge only a few seconds after power was applied. This unit, which had worked correctly in vacuum tests, will undergo further testing to determine the failure mechanism. An in-air motor firing circuit also failed a ground test at the launch site: the SCR triggered even though the trigger circuitry was unpowered. Hence we chose to not attempt an in-air ignition.
4. Melissa Rogers kindly took and organized pictures of instrument construction and testing, and also documented the 13Oct adventures.
5. MORE SUCCESSES: Two successful flights out of Mansfield, WA on 3May08. Since last October, causes of the problems were identified and corrected. The chute deploy problem was due to an improper arming procedure and a documented limitation of the chute deploy electronics. That system, when quickly cycled through an on-off-on power sequence, ignites the chute deploy charge within seconds of the last power-on. The in-air motor ignition system failure was from an open ground connection between the ignition and accelerometer circuits. On 3May, we tested the corrected chute deploy and in-air motor ignition systems in two flights. For each flight, the apogee and main chute deployment systems functioned nominally. On the second flight, we also tested the in-air motor ignition system by having it ignite 2 grams of black powder, located in a motor tube. The tell-tale puff of smoke was visible within seconds after motor burnout. We also tested a newly developed radio-teletype data link from rocket to ground. This system telemetered acceleration and altitude information to ground on the first flight. On the second flight, a nose cone shock at chute deploy disconnected the transmitter's 9V battery, resulting in telemetry loss from that time on.
Meeting Times and Locations
Lectures are MWF 9-10AM in JHN 127. An up to 3 hour lab period follows immediately in the same room.
Art of Electronics, Horowitz and Hill: This is a practical book; it is very good as a general reference for electronics associated with measurement tasks.
Introductory Electronics for Scientists and Engineers, Simpson:
Older, slightly theoretical book. Good coverage of the basics.
Op Amp Applications Handbook (W. Jung, ed): downloadable intro to opamps from Analog Devices. This is a collection of sections written by different folks, so the style is uneven and the material is not tightly organized. However, Chapter 1 presents a detailed summary of introductory material.
Eagle parts library: collection of ESS472 parts
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Last modified: 8May08 15:01