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Hello and welcome to today's Aerospace Team Online chat with Brent Nowlin from NASA Glenn Research Center.

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Brent Nowlin is responsible for making sure medium- and large-scale gas turbine engines function properly. Brent's job is similar to the role of [operations] engineers on any sci-fi movie. Operations engineers are responsible for maintaining and running equipment. If the equipment fails to work properly, operations engineers are usually responsible for fixing it.

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And now, here is Brent Nowlin to answer your questions.

[ BrentNowlin/GRC - 8 - 10:04:58 ]
RE: [Kylee] My classroom is doing a project one Mars and I was wondering if you could assist me on which direction to go and what information would be most interesting! Thank you!
Kylee, Despite being somewhat close to Earth, there's a lot of information that scientists still would like to gather. Information about the atmosphere and the geography of the planet are two things that come to mind. Another question that has come about is, how much water is there on Mars? I would suggest that information about these questions would be a great project. I believe that NASA's Jet Propulsion Laboratory has a web site that would have some information about these questions, and what steps are being taken to answer them.

[ BrentNowlin/GRC - 22 - 14:36:59 ]
RE: [MsMurphys5thGraders] How many repairs do you make in a year?
We repair things as much as needed! Some repairs are pretty minor. Some, such as the bearing failure, are extremely major. Usually, when the facility is running and obtaining data, there are a couple of things that need attention every day. Most of these things are very minor, taking a few minutes to fix. It also depends on where the facility is in terms of its operation - is it in buildup status (things being installed), checkout status (running to check out equipment), or run status (collecting research data)? In buildup and checkout status, repairs and modifications are extremely common. Once operational, repairs aren't as time consuming.

[ BrentNowlin/GRC - 23 - 14:38:03 ]
RE: [MsMurphys5thGraders] What is the hardest part of your job?
That's a really tough question. I guess that putting together reports is pretty tedious (and boring!). It's something I really don't enjoy, but usually is necessary.

[ BrentNowlin/GRC - 24 - 14:39:14 ]
RE: [MsMurphys5thGraders] Have you ever found one engine you couldn't repair?
Sometimes engines, and their components, are damaged beyond repair. In this case, we either get a new one, or simply cancel the test.

[ BrentNowlin/GRC - 25 - 14:39:43 ]
RE: [MsMurphys5thGraders] How long have you done this job?
I've been here almost 13 years.

[ BrentNowlin/GRC - 26 - 14:40:08 ]
RE: [MsMurphys5thGraders] What is the biggest problem you have dealt with?
The biggest technical problem.....I guess that would be the motion system. We use measurement probes that are moved around the flowpath. The probes measure temperature, pressure, and flow angle, among other things. Moving them around means that you can get the entire "picture" of what is going on in the flowpath with one probe, rather than having a large number of probes that didn't move. The system we had used wasn't very good. It simply did not do the job for us. So we developed a system that would. It took a long time - about 2 years of working on it off and on. But it works, and the satisfaction of seeing it work is really great.

[ BrentNowlin/GRC - 27 - 14:41:06 ]
RE: [MsMurphys5thGraders] How long does it take to build a new turbine?
The turbines generally take a year or so to build. There's an incredible amount of machining that goes into them. Installing them into the test facility takes anywhere from a couple days to a couple of months, depending on how complex the research hardware (the turbine and its associated pieces) is. It's real important to remember that at NASA-Glenn, we test new turbines, not necessarily the turbines that are in use on aircraft. We try to find ways to improve the turbine efficiency, as well as the efficiency of other engine components. So these turbines that we test are not made in large numbers - usually there's only one or two made.

[ BrentNowlin/GRC - 28 - 14:41:40 ]
RE: [MsMurphys5thGraders] Have you ever made a mistake? What is your best success story?
I guess my feeling is that if you haven't made a mistake, then you're probably not doing too much. I have made plenty of mistakes. Most of them are the result of thinking that something worked one way, when it turns out that it works a different way. Also, in computer software, mistakes are very easy to make, and sometimes you don't even know there is a mistake until much later. Most of the safety systems in the test facilities are designed to prevent something really bad from happening if something does go wrong. The safety systems are checked out periodically to ensure their functionality. My best success story is the motion system mentioned above. There is a patent application being prepared for it, and there also is interest from some companies that want to use it elsewhere. It really was fun, and challenging, to develop.

[ BrentNowlin/GRC - 29 - 14:43:00 ]
RE: [MsMurphys5thGraders] If you couldn't be an electrical engineer what would you do?
Actually when I was about your age (5th grade), my first choice in terms of occupation was to play center field for the Detroit Tigers. That didn't pan out too well. My second choice was to be an electrical engineer. I really haven't thought about what I'd do if I wasn't an engineer. I suppose that being a full-time farmer wouldn't be too bad. But farming is an awful lot of hard work! On the other hand, there are many different avenues of electrical engineering. I would probably pursue another facet of engineering, if my current responsibilities had to change.

[ BrentNowlin/GRC - 30 - 14:44:46 ]
RE: [MsMurphys5thGraders] What was the most damaged repair?
On the projects I have worked on, there have been two incidents that led to damage. The first incident happened about 8-9 years ago. In our small turbine testing rig, we were trying to see how much efficiency would be gained if we decreased the clearances (gaps) between the rotating turbine and its stationary housing. Unfortunately, some really strange heating took place, which made the turbine wheel get bigger than expected. It expanded into the housing. The friction coming from the metal-to-metal contact, while the turbine was still spinning, was enough to melt the back side of the turbine wheel, as well as the housing that it rubbed against. The turbine wheel was damaged beyond repair, since it couldn't be trusted to keep together, even if it were machine smooth again. For this part of the project, this test was cancelled. The other repair was the bearing failure that I mentioned in #3. The facility that the bearing failure happened in is incredibly complex, which is why it took so long to replace the bearing. The bearing was replaced, and the test facility was put back together again and run.

[ BrentNowlin/GRC - 31 - 14:47:18 ]
RE: [MsMurphys5thGraders] What kinds of tools do you use? Do you use any computers or special software to diagnose problems?
The tools we use range from simple small screwdrivers (we call them "tweakers"!) to computerized equipment that may cost many thousands of dollars. Many of the systems today are computerized, so by that simple fact, a computer is involved in any type of problem that may arise. Also, the systems today are integrated, meaning that different systems transmit information to each other. The computers and computerized troubleshooting tools we use are crucial for those types of problems. As for the software, we use software mostly as a tool to operate the facilities, control other systems, and to gather data from the facilities.

[ BrentNowlin/GRC - 32 - 14:55:12 ]
RE: [MsMurphys5thGraders] How many other people do you work with?
On any given project, there may be just me, or there may be 100 people involved from start to finish. I'd say that for most activities, there are probably a dozen people that I work with routinely on a daily basis.

[ BrentNowlin/GRC - 33 - 14:56:06 ]
RE: [MsMurphys5thGraders] Have you ever been hurt working with such large engines? Is this work dangerous?
I haven't been hurt, but others have been. The stuff we work with must be respected at all times. As soon as someone forgets that, usually something gets damaged, or worse, someone gets hurt. The turbines that we test are about 24 inches in diameter. That may not seem that much, but that turbine spins at 8000 revolutions per minute (rpm). That means that in one minute, the turbine will make 8000 full revolutions (turns), or about 133 revolutions per second. Again, that may not seem that fast, but the turbine can generate more than 2000 horsepower in shaft power. Furthermore, if the turbine were to suddenly become disconnected from its power absorber, it would almost immediately spin so fast that it would fly apart. The pieces from something that large would go through concrete walls! We take a lot of precautions to ensure that this doesn't happen. Other factors to consider are electrical shocks and chemicals. We have safety committees here to try and make sure that everyone knows of the safety issues and understands them.