[ Susan/NASAChatHost - 5 - 12:59:30 ]
Welcome, we have Steve Smith online here today to answer your questions.

[ Steve/Ames - 6 - 13:02:35 ]
RE: [Sarah/Greenmeadow] would you rather do wind tunnel work or computational work on computers?
Well, it seems like I'd always rather be doing the other one from what I am now....I'm just kidding! but each one has its own trials and troubles, and also its own rewards. Thats why I do some of both. I guess if I had to pick, I'd say I like the computer more.

[ Steve/Ames - 11 - 13:07:02 ]
RE: [Sarah/Greenmeadow] When you talked about the mesh for the computer program is that like drawing little boxes to describe the shape of the plane
Yes, the surface shape of the airplane is described in the computer by dividing up the surface into small boxes. The corners of the boxes are points (x,y,z) that tell the program where the surface is. Some computer models need grid in the flow region off the body too, so then we need to divide up all the space around the outside of the airplane with a 3-dimensional grid. This is very tedious, but the results are usually worth it, because you get information about the flow everywhere.

[ Steve/Ames - 12 - 13:07:30 ]
RE: [Sarah/Greenmeadow] What color is your new plane going to be?
My homebuilt airplane will be white with blue trim!

[ Steve/Ames - 14 - 13:09:12 ]
RE: [Susan/NASAChatHost] Steve, what are you working on now?
I've still been working on the buffet loads predictions on the Hawker Horizon business jet. I recently got better comparisons with wind tunnel data by computing the wing bend of the wind tunnel model, and putting that bend into the computational model. It really helped get better answers. Next, I need to improve the turbulence models.

[ Steve/Ames - 15 - 13:10:39 ]
RE: [Sarah/Greenmeadow] What part of the plane are you working on now?
I am starting to make wing ribs. Ribs are the metal pieces that help form the special airfoil shape of the wing. I need to make 60 ribs! This is the slowest part of building the airplane. After the ribs are finished, everything else will go pretty fast.

[ Steve/Ames - 17 - 13:13:47 ]
RE: [Steve/Ames] I've still been working on the buffet loads predictions on the Hawker Horizon business jet. I recently got better comparisons with wind tunnel data by computing the wing bend of the wind tunnel model, and putting that bend into the computational model. It really helped get better answers. Next, I need to improve the turbulence models.
Turbulence models affect the way the flow behaves at very small scales. Details of how the flow interacts with the surface of the wing can be affected. The turbulence model I have now is an old one, and there are much better ones now. So I hope when I get the new one, my results should be very close to the experiments.

[ Steve/Ames - 19 - 13:15:48 ]
RE: [Susan/NASAChatHost] Are you comparing it to the turbulence model of your own wind tunnel test or someone elses test I ask because I am interested in how researchers share data and techniques.
The experiments were done in a British wind tunnel by people from Raytheon Aircraft Co. I'm using the Baldwin-Lomax turbulence model, which is quite old. The new one is called Spalart-Almaras. Philipe Spalart used to work here at Ames, but he moved to Boeing.

[ Steve/Ames - 21 - 13:18:47 ]
RE: [Sarah/Greenmeadow] I think I would like the computer work better too because you would get results faxter.
Yes, you are right....To build a godd wind tunnel model takes several months, then you must wait for a turn in the wind tunnel. At first, all the measurement instruments don't work right, and it takes days to get it all working. This part can be fun though, its like being a detective. On the computer, it often takes a month to build the computer model of the airplane, but then you just run it through the program. But sometimes it takes 2 days to get an answer back. If the program doesn't work, then its like detective work again to find out why. Getting everything working is half the fun.

[ Steve/Ames - 24 - 13:20:31 ]
RE: [Sarah/Greenmeadow] Could you make a model of your homebuilt airplane?
well, I will probably make a desktop display model of it to show people. I already have a computer model of just the wing, to help design it. Mostly, I want to work on building the airplane, not spending too much time analizing it, now that the wing design is finished.

[ Steve/Ames - 26 - 13:22:19 ]
RE: [Susan/NASAChatHost] I wonder, why Ratheon would do a test in a British tunnel?
Well, Raytheon bought a british company, Hawker aircraft, and they had much experience in that tunnel, so they went back there for their new design. I don't know if the Hawker people had the design started or not when they were bought out.

[ Steve/Ames - 27 - 13:24:36 ]
RE: [Sarah/Greenmeadow] Thank you for answering my questions, I would like to design a plane from start to finish but it doesn't sound like you get to do that at NASA, why?
Sarah, thats a really good question. The main reason is that we do research, and the airplane companies are in the business of designing and building airplanes. But sometimes, our research leads to a new kind of airplane no one has built before, and so NASA would hire a company to help work with the NASA people to build it. That doesn't happen as often as I would like, because its pretty fun to see your own design go to flight!

[ Steve/Ames - 30 - 13:29:10 ]
RE: [Sarah/Greenmeadow] In your journal you wrote about the curves that resulted from changing your model, I didn't really get what those curves were about. can you say what your were measuring and why it was important?
Uhm, I forget what I wrote....was I talking about curves of plotted results, or curved surfaces ON the model, maybe if you say a little more about what I was talking about, I will remember and then I can answer?

[ Steve/Ames - 33 - 13:32:41 ]
RE: [Parker/HomesteadHigh] do you have to get your airplane approved by the FAA before you fly or is it like an ultralight where you do not need a piolots license or anything to fly it
Hi Parker, My airplane will be licenced as "Experimental-Amateur Built" by the FAA. An FAA inspector looks at the plane at different stages of construction to make sure its built in accordance with accepted practices. Then, when its finished, it gets a temporary licence thats good for 40 hours, with no passengers, and can't fly over anyone's house. Once it flys safely for 40 hours, its gets its regular "experimental" certificate. The FAA established this category to allow howme-builders to make their own planes, but to protect the public so dangerous planes don't fly around.

[ Steve/Ames - 35 - 13:33:43 ]
RE: [Sarah/Greenmeadow] wow! is that like an X-plane?
Yes, exactly. Sometimes we just call it a "technology demonstrator" and sometimes, when they want a lot of publicity, they call it an X-plane.

[ Steve/Ames - 37 - 13:34:58 ]
RE: [Parker/HomesteadHigh] Do you give the airplane builders like Ratheyon and Lockheed the raw data from the tests or do you tell them to change the shape of the wing this way or that.
Good question! Sometimes, we just exchange analysis data, either from wind tunnel or computer. Sometimes, we have cooperative programs where we help design, so then I would give them a different shape and show why its better.

[ Steve/Ames - 39 - 13:38:30 ]
RE: [Sarah/Greenmeadow] I think it was about deltan lift and drag so that must mean the change in lift and drag at different angles of attack but that's about as far as I could follow what you were saying
Oh, yes, the curves are the lines that you make when you make a data plot. Like an x-y axis, and you have an equation for y-values at different x values that forms a line. Well, I might do just a few computer runs and get a few data points of y values and x values. Then, I plot them and draw a curve through the points. The curve is a way of estimating what the values would be in between the data points I have. sometimes, when we do it mathematically, we call it "interpolation" but sometimes we do it graphically by making a smooth curve....it helps people understand how something behaves because they can see the effects of one variable in a smooth way. Does that help?

[ Steve/Ames - 40 - 13:40:52 ]
RE: [Parker/HomesteadHigh] Does Ames have the fasted computer in the world or do they have one on the fastest (Cray). I heard of a computer developed by Intel called ascii red that uses thousands of pentium chips which makes it very fast.
Ames has 2 Cray C-90's which are very fast "serial" computers, and then we have some SGI "origin-2000" parallel computers. We tend to develop computers that work on our types of problems. I don't think we have any "massively parallel" machines with thousands of processors. People are starting to talk about how we might use them.

[ Steve/Ames - 42 - 13:42:47 ]
RE: [Sarah/Greenmeadow] Did you ever get to work on an X-plane?
I have gotten to work on a couple of technology demonstrators - but they never got built. My father helped build one when he worked here. And some of my friends at Stanford have made 2! They were radio controlled, What we call a UAV, an unmanned air vehicle. with cameras in the nose, and autopilots, and computers inside the airplanes.

[ Steve/Ames - 43 - 13:43:23 ]
RE: [Sarah/Greenmeadow] Thank you looks like I need more math,
Sarah, what grade are you in? What are you studying?

[ Steve/Ames - 45 - 13:45:19 ]
RE: [Sarah/Greenmeadow] Do you have to take more training on computers when they come out with new ones or is it easy to go from one to another.
Well, I have a little bit of a hard time. They try to make them all work the same now, with the UNIX operating system, you can pretty much get right to work on the new computer. But I think UNIX is harder to use than other operating systems that are more logical and friendly....like my MAC!

[ Susan/NASAChatHost - 47 - 13:47:33 ]
Wow this chat is going fast, we've got about ten minutes left.

[ Steve/Ames - 49 - 13:49:36 ]
RE: [Sarah/Greenmeadow] I am in ninth grade, my uncle is a pilot and my granpa too!
Wow. Pretty soon, you'll be learning Geometry, if not already. Geometry is pretty useful. You will see what I mean about the x-y plots. Then you will study calculus if you are interested in science and math. Calculus will not seem useful right away, but it is the foundation for almost all of modern science. Without even knowing it, we use it or depend on it every day. What does your father fly?

[ Steve/Ames - 51 - 13:51:50 ]
RE: [Sarah/Greenmeadow] Do you have to write all the computer code yourself or do you ever have to workin teams?
OOPs, sorry, I mean your Uncle. I sometimes write my own computer programs, and sometimes I modify other people's programs, and sometimes I use a program someone else wrote directly. it depends. Its really important to know some programming so you can understand how a program works even if you don't change it. We don't treat our programs like a black box, like microsoft word or something, where you just use it....

[ Steve/Ames - 53 - 13:54:06 ]
RE: [Parker/HomesteadHigh] Where these UAV's like the EARTH planes that some at Ames are working on
One was a 20 foot wingspan model of an OBLIQUE WING...and the other was a 17 foot model of a BLENDED WING-BODY. These were both written about in Aviation Week, and maybe even Popular Science. The ones I helped on were an Oblique wing on a modified F-8 Crusader fighter plane, and a JOINED WING, that would be built from scratch as an experimental.

[ Steve/Ames - 56 - 13:55:44 ]
RE: [Steve/Ames] One was a 20 foot wingspan model of an OBLIQUE WING...and the other was a 17 foot model of a BLENDED WING-BODY. These were both written about in Aviation Week, and maybe even Popular Science. The ones I helped on were an Oblique wing on a modified F-8 Crusader fighter plane, and a JOINED WING, that would be built from scratch as an experimental.
There is some great work on earth-observing airplanes at NASA Dryden research center at Edwards AFB. The Pathfinder has flown up to 72,000 ft on solar power! It was built by a small company called Aerovironment, with NASA help and funding.

[ Steve/Ames - 57 - 13:56:26 ]
RE: [Sarah/Greenmeadow] my dad is a lawyer but my uncle flys 767's for Delta, thanks for answering my questions, Bye.
Bye Sarah, Thanks for coming.

[ Steve/Ames - 58 - 13:57:37 ]
RE: [Parker/HomesteadHigh] Would you rather work on an operating system that is friendly like mac or win95 or a robust error free OS like UNIX or UNICOS
I'm not sure I would call UNIX error-free! its usually the new implementations on new computers that cause the problems. Bye Parker

[ Susan/NASAChatHost - 59 - 14:14:14 ]
Thanks Steve you had great answers for Sarah and Parker. I learned a lot from you today too!