Tuesday, March 24th, 2008
Alaska Microgravity team on the radio. Listen to recording of the KUAC March recording. Download now
Tuesday, March 18th, 2008
Alaska Microgravity Team in the News! As our flight date rapidly approaches, our audience is growing: in the last month we have appeared in the UAF Sun Star, Fairbanks Daily News Miner, Anchorage Daily News, Juneau Empire, and Ketchikan Daily News. Thanks to the Associated Press, our story is getting out Alaskans everywhere. We're grateful for all of the support!
Thursday, February 21st, 2008
We have our first video! This is the first in the series of videos showcasing our activities here at uG.
Tuesday, December 11th, 2007
We absconded with the 88 [mH] Helmholtz coils from the EE203 lab and set them up around our prototype. With the coils properly spaced and the prototype elevated to the level of the center axis, we plugged in a power supply and powered up the system. The power supply showed promise of delivering over 10 [A], but the "overvoltage" indicator would kick-in at about 4 [A]. We recognize that we're overlooking something in this circuit which is activating the kill-switch, but the reason is not yet clear. More over, we were not able to get our prototype to turn! We constructed a Matlab routine to calculate the maximum torque output available from the coils and the minimum torque required based on the moment of inertia of our prototype--our output torque was vastly under our required torque. But we tweaked the Matlab routine and arrived at a design that theoretically will give us sufficient torque to overcome inertia and friction (of the lazy susan) without making unrealistic power demands. We're also exploring several options to reduce our moment of inertia.
Monday, December 6th, 2007
We've been selected for the 2008 Flight Campaign! The Reduced Gravity Student Flight Program has officially announced the selectees for the 2008 flight, and we are on page three (click here to see)
Friday, November 23rd, 2007
The UAF MicroGRAV team celebrated the Thanksgiving holiday by fabricating prototype magnetic torque coils, and configuring them such that we caused a magnet, placed at the center of perpendicular coils, to rotate very rapidly.
Some of our members also work on the Alaska Student Rocket Project (ASRP), and thus all the equipment is available to MicroGRAV as well. The ASRP spintable was modified to support our coil winding needs. We made 4 coils in total: two small coils intended to be the ACS mechanisms, and two larger coils which were intended to be used in a Helmholtz configuration and provide a stationary magnetic field which the ACS coils would use for control. The coil winding process was very exciting and the Hall effect sensor we used to count the rotations would spontaneously reset. As a result, we have a rough estimate of the number of windings in each coil, but not exact values for flight hardware, our manufacturing procedures will be more stringent on quality control.
We "borrowed" a spare battery pack from ASRP, to which we attached a lazy susan. The control coils were connected to an HCS12 microcontroller via simple H-bridge circuit and controlled remotely through a wireless connection. Jesse had written some code which allowed a user to direct the current through the coils with a standard computer joystick. We used modeling clay to mount the coils and the electronics to the top surface of the battery pack. The ACS coils were mounted perpendicular to each other. To visualize the effect of the magnetic field we were able to create, we put a small magnet at the center of the coils and gave 'em juice. The outcome was most exhilarating! By gently increasing the current through the coils via the joystick, the magnet would stand itself up on edge and rotate. If too much current was delivered to the coils, the magnet would lose stability and fling itself away in a random direction. Perhaps if the coils were more uniformly fabricated, and precisely aligned, then maybe the magnet would be more stable at higher angular velocities.
In the process of removing the centers of the frames for the Helmholtz coils, we unfortunately managed to nick one with a drill bit. In an instant 300 windings of AWG#34 magnet wire instantly became rubbish! Even a small nick, as we experienced, meant no current would flow, and thus the coil was suitable only for a lab decoration. As a result, we were unable to test the effectiveness of the control coils in the presence of a magnetic field.
We took some pictures and video recordings of our weekend activities, but haven't finished processing them yet. Check back soon to get a glimpse of our fun!