Rocket Powered

Mark Hopkins

Guest blogging today is Saket Vora, answering my challenge to share  some of the most interesting ways in which Lenovo PCs were being used.   I think Saket and colleague Nader certainly rocket their way past interesting and into the extraordinary territory - at least in my book.  Hope you will agree.  

Saket Vora

Chalkboard sessions and problem sets tend to dominate experiences in academia, but at Stanford University the value of a hands-on learning experience is still highly valued. In the graduate level course on rocket propulsion, student teams are tasked with designing, constructing, and testing a real rocket engine. The 2007-2008 Stanford AA284 project team decided to design a hybrid-fuel rocket suitable for a lunar lander descent - delivering a 50 kg payload through 2500 meters per second of velocity change to the lunar surface. Stanford graduate student Nader Moussa led the project team, and designed the electronics for control and data acquisition. The team also included six aerospace engineering colleagues, who engineered the rocket thermodynamics, mechanical, and propulsion system with guidance from NASA Ames rocket scientist Dr. Greg Zilliac. Nader is a longtime Thinkpad user, and all of the control software and hardware was developed on the Thinkpad X31 he's used daily for the past five years. This notebook has taken Nader through three engineering degrees and survived more than 15,000 miles of travel. "The X-series are marketed for their portability," Nader said. "But my X31 had no trouble running 3D engineering CAD, microcontroller software compilers, rocket thermodynamics simulations, and our custom data acquisition and control programs. It was a miniature engineering workstation." The actual rocket control was performed by a flight-size 16-bit Renesas M32C microcontroller running a simple real-time operating system. This "flight computer" interfaced with theThinkpad X31 running Windows XP, located at the test stand. The X31 stored the burn parameters, issued controls to the rocket, and recorded performance data of the burn. It also allowed the engineering team to access and monitor the rocket from a safe distance, using comfortable, familiar software tools. A Thinkpad T40p, connected via ethernet cable, served as a remote terminal to the X31 and was located at the test burn's "mission control."

rocket-12

Gas flow thermodynamics testing - with the system safed, Nader uses his X31 Thinkpad to log into the rocket computer and check tank pressures.

The test firing took place atop of a parking structure at the edge of campus. Approximately 800 pounds of sandbag and steel structure held the coolant tower, oxidizer tank, and combustion chamber to the ground. One of the biggest worries was that coolant water would reach the Thinkpad and other electronics. Safety was naturally a top concern. The first burn served as safety and shutdown checks. The primary burn featured an initial thrust phase, a brief shutdown, then a second thrust phase, thus simulating a controlled descent to the lunar surface in two burns.

Success! This test proved to be the largest rocket engine firing in the history of the course, and the first to successfully hot-restart (reignite) the engine during a field-test. Data was collected for thermodynamics, burn-rate, and gas flow analysis. Because the rocket controller directly downlinked to the Thinkpad X31, it was possible to perform instant data analysis. We applied industrial strength thermodynamics code and burn profile plotting to the field data, only seconds after the burn completed.

This ground test advanced the state of the art in hybrid rocket research. As for the X31, the burns coated it with a fine layer of hydrocarbon dust, which never really wore off. It later served as a robot controller, RADAR controller, and a web server, before finally retiring after serving six years on the original battery. Nader now uses a Lenovo S10e for mobile computing.

 

For more technical information on the rocket project, see http://www.stanford.edu/~nwmoussa/school/demo/aa284.hybrid-rocket.poster.pdf