Aluminum Tubes!

Pretty much since the day I finished flight school I've been working 20-30 hours a week for Dr. Eric Petersen on his newest research project. When I got here all we had was a giant aluminum tube and its endcaps. Ever since then, I've been ordering bolts, screws, pressure transducers, thermocouples, DC amplifiers, valves, fittings, connectors, control panels, electronic assemblies, lumber, electropneumatically actuated ball valves, vacuum pumps, and other assorted lab supplies. The only things I've built so far are the supports for the giant aluminum tube, which I cut out of a 4"x4", and an upper level of an optical table that I have to redo because it wasn't professional enough (read: it wasn't expensive looking enough, so I have to buy thick aluminum rods and build and paint a new upper level instead of using the steel pipe, flanges, and plywood I bought from Home Depot, plus the 1/2" plywood bends a little too much, and by a little, I mean barely).

The experiment works like this; we have a few tanks of compressed gasses in giant SCUBA tanks, one each hydrogen (fuel), oxygen (oxidizer), and nitrogen (or something non-flammable). The hydrogen and oxygen will be fed and pressurized into a mixing tank so the right chemical composition and continuity of the gas is fed into our main chamber. The main chamber is an 11.75" ID, 14.25" OD aluminum tube up on an optical table. We pressurize the tube anywhere from 100-450 psi (about 7 to 30 times standard atmospheric pressure). On the endcaps of the tube there are 2" thick lexan (bulletproof) glass plates so we can point cameras and other optical equipment at the center of the tube. In the center is an electrical sparker with a 5000 volt potential difference that creates our spark. Once the capacitors are charged, we flip the switch and if my designs are within safety factors, I won't be incinerated by the blast. Using a $30,000 high speed camera, we'll take pictures of the expanding blast sphere, and from simple frame rate calculations we can accurately measure just how fast this gas explodes. Once the test is over we open a valve to vent out the hot gases, and then open another and turn on a vacuum pump to clean out the system.

The purpose of the experiment is to simulate high pressures experienced in rocket engines to establish behaviors of these gases under these conditions. These tests have been done under atmospheric conditions but not under high pressures. What's crazy is that this and two other shockwave experiments are being carried out in the Gas Dynamics Lab... which is located in a regular office building, the same one the alumni association is headquartered (Lorraine Weinstock might still work here, but I haven't seen her since I started). If something goes awry, lots of people can get hurt or be laid off, so I'm making sure everything has a high safety factor, because 30 atmospheres, even contained in a 1500 cubic inch chamber behind 6" thick walls made from plywood, sand, more plywood, and sheets of stainless steel, is deadly.

The worst part of the job? I've been working since the end of May and I still have not received a paycheck. The first pay period that went by I couldn't get paid because I didn't quite have all the paperwork done because I wasn't enrolled in any classes. Had I been enrolled as a student it would have worked out. The next pay period I still wasn't in the system because of my old job with SARC tutoring physics. My records were in place and had to be taken off by my old boss, who did it in a timely manner, but because the lady in accounting with the engineering department is never there, she didn't get it in time. For the third pay period I have no idea what happened, and by that time I had $30 to my name and was out of gas. Hopefully, if FedEx gets my signed timesheets here by tomorrow from LA where my boss has another lab, I should get a hefty paycheck next Friday. The job pays $12 an hour, which is $3/hr better than flipping burgers and frying fish like my last job, plus I work in the coldest building in the hottest months of Florida. Pretty sweet if you ask me.

In addition to working, I've also been building model airplanes and rockets (until I went broke and had to play video games). So far I've built two model airplanes, a P-51D Mustang and an F-16, and three rockets, a standard Estes Alpha III, an SR-71 Blackbird, and an X-Prize winner whose name escapes me at the moment. I still have yet to launch them, but I'd like to make it an AIAA outing so other people can bring their rockets and we can share some engines. I also bought a new bass guitar since my old roommate took his back. I can't wait to learn some new songs. I'm also thinking about buying an electric or acoustic guitar to learn to play as well, even though everyone tells me bass is a whole lot easier.