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March 24, 1998
Questchat with Stephen Jaeger

Aeroacoustic Engineer

[ Stephen/Ames - 7 - 10:00:29 ]
RE: [Susan/NASAChatHost] Good morning from NASA Ames Research Center! Stephen is here and ready for you questions.
Hi there

[ Stephen/Ames - 8 - 10:01:45 ]
RE: [Susan/NASAChatHost] Stephen can you tell us a little bit about what you've been working on lately?
I am working in the 7- by 10-foot Wind tunnel at NASA Ames, using our 100 microphone array to measure the noise of an aircraft wing.

[ Stephen/Ames - 11 - 10:04:17 ]
RE: [Carl/homeschooled] Hello
Hi how are you?

[ Susan/NASAChatHost - 12 - 10:04:25 ]
RE: [Carl/homeschooled] Hello
Hi Carl, do you have a question for Stephen?

[ Stephen/Ames - 14 - 10:06:02 ]
RE: [Susan/NASAChatHost] Do you work with Aerospace engineers that are trying to solve a certain problem?
One of the problems we are trying to solve is how to reduce the noise created by airplane wings. So aerospace engineers and acousticians come together to try to design a quieter wing.

[ Stephen/Ames - 15 - 10:07:27 ]
RE: [Carl/homeschooled] Have you ever done aeroacoustics work on partsof a helicopter?
There is a separate group of people who do helicopter studies but I usually work on airplanes. Helicopters are a difficult noise problem.

[ Stephen/Ames - 20 - 10:11:07 ]
RE: [Dan-Deborah/YpsilantiCOPE] You mentioned using diamonds for aerospace applications. How are the diamonds used?
Diamonds are the hardest substance known so it is a very useful substance for aerospace applications. One of the things they want to use it for is to coat airplane surfaces to resist damage and heat.

[ Stephen/Ames - 21 - 10:12:37 ]
RE: [Susan/NASAChatHost] When you are working in the wind tunnels are there certain problems you have to overcome?
Many problems: equipment that doesn't work right, computers that wont boot up, software with bugs, cold coffee....8-)

[ Stephen/Ames - 22 - 10:13:22 ]
RE: [Mike-Deborah/YpsilantiCOPE] Have you ever flown a supersonic jet?
No...just little Cessnas. It would be fun, though.

[ Stephen/Ames - 24 - 10:14:55 ]
RE: [Carl/homeschooled] Do you try diffrent materials or just diffrent wing shapes?
Mostly in the type of work we do , we are interested in the devices that help the wing get lift. Like the flaps and slats. By designing those properly and testing them in the wind tunnel we can come up with designs that are quieter.

[ Stephen/Ames - 26 - 10:16:49 ]
RE: [Karen-Karen/BigforkElementary] Are people in the modle airplane while the plane is in the wind tunnel?
NO, not these days. That would probably be dangerous. But 20 years ago I know that they actually had someone in a full size jet flying the thing while it was in the wind tunnel! Must have been a lot of fun!

[ Stephen/Ames - 27 - 10:17:15 ]
RE: [Mike-Deborah/YpsilantiCOPE] Have you ever worked with Steve Smith at Ames? We chatted with him before.
Sounds familiar. I might have.

[ Susan/NASAChatHost - 31 - 10:20:13 ]
RE: [Stephen/Ames] Sounds familiar. I might have.
Steve is an Aerospace Research Engineer in the High Speed Research Branch. He's worked on things like the oblique wing.

[ Stephen/Ames - 32 - 10:20:44 ]
RE: [Deborah/YpsilantiCOPE] Does your work involve safety back-up system design to prevent pilot error related to deployment of flaps and slats? We live near Detroit where a terrible crash happened because of this issue.
I remember that accident. Slats are a very important part of a jet liner. They have to use some sort of "high lift" system to get the airplane off of the ground, otherwise it would take a lot of runway. The pilots in that case forgot to lower them before taking off (if I recall.) My work mostly involves trying to measure the noise of these devices so that the airplane is quieter when it is landing.

[ Carl/homeschooled - 33 - 10:21:31 ]
Karen depends on if its in the earths atmoshpere or if it can get past 80,000 feet

[ Stephen/Ames - 35 - 10:23:05 ]
RE: [Carl/homeschooled] Hmm have they tryed leading edge flaps/alerons? Maybe having both trailing and leading edge flaps can get the same effect with less air resistance...
Modern jet liners use both leading edge slats and trailing edge flaps to increase the lift of the wing. This is one of the configurations we are testing in the 7 by 10 wind tunnel. (I haven't worked with leading edge flaps)

[ Stephen/Ames - 37 - 10:24:51 ]
RE: [Karen-Karen/BigforkElementary] How fast is the fastest supersonic jet?
Supersonic, of course, means it travels faster than the speed of sound which is about 700 miles per hour. the Concorde, a supersonic airliner, can go Mach 2 ...twice the speed of sound, 1500 miles per hour. It can go from London to New York in about 3 hours! Cool!

[ Stephen/Ames - 41 - 10:27:28 ]
RE: [Mike-Deborah/YpsilantiCOPE] How did the test with the starter pistol in the 40 by 80 foot wind tunnel work out?
When we do acoustic test we don't want any reflections from the wind tunnel walls. We are trying to simulate what it would be like outside. We fire off the starter pistol or the cannon to produce a loud noise, then we record the echo that comes back. This tells us how reflective the walls are. It works very well.

[ Stephen/Ames - 42 - 10:28:29 ]
RE: [Deborah/YpsilantiCOPE] Why is the "airbus" so noisy? There is a funny vibration related noise.
Airbus airplanes are noisy? Hmmmmmm, I don't know.

[ Stephen/Ames - 43 - 10:29:55 ]
RE: [Karen-Karen/BigforkElementary] What was your favorite subject in elementary school?
Elementary school? Wow that was a long time ago. 8-> I remember now: It was Science

[ Stephen/Ames - 44 - 10:31:19 ]
RE: [Mike-Deborah/YpsilantiCOPE] Are there military applications for your work?
Not that I know of. Military airplanes are so fast that by the time you heard the airplane attacking you...it would be too late. Helicopters are slow though so noise DOES matter.

[ Stephen/Ames - 47 - 10:32:17 ]
RE: [Carl/homeschooled] The X-15 can go past 80,000 feet and past 6000 miles per hour easy... ovcourse they tend to blow up alot
The X-15 was an incredible airplane. The research they did led right up to the space shuttle.

[ Stephen/Ames - 49 - 10:33:33 ]
RE: [Karen-Karen/BigforkElementary] How many gallons of fuel does the Concord need to fly from London to New York?
I heard once that it eats something like 20 tons of fuel an hour! It must have one large gas tank!

[ Stephen/Ames - 53 - 10:36:28 ]
RE: [Dan-Deborah/YpsilantiCOPE] What is your next project after this one?
My next project will be to test the new test section of the 40 x 80 wind tunnel. They just completed a $25 million project to make the test section "anechoic" that is to make the walls less refelctive. I will fire off the pistol and use other methods to see how good a wind tunnel we got for your $25 million!

[ Susan/NASAChatHost - 54 - 10:38:07 ]
RE: [Stephen/Ames] My next project will be to test the new test section of the 40 x 80 wind tunnel. They just completed a $25 million project to make the test section "anechoic" that is to make the walls less refelctive. I will fire off the pistol and use other methods to see how good a wind tunnel we got for your $25 million!
I hope you'll write a journal about that it sounds like it would be fun to read!

[ Stephen/Ames - 55 - 10:38:51 ]
RE: [Dan-Deborah/YpsilantiCOPE] What kind of computers and software do you use?
We use HP computers with UNIX operating systems, software to acquire acoustics data, disk drives that store 25 gigabytes of data, parallel processors to crank through all of our data and I am talking to you on my trusty Macintosh.

[ Stephen/Ames - 56 - 10:40:45 ]
RE: [Sarah-SeattleWA] How did you get interested in aeroacoustics?
I sort of fell into it. I wanted to work on jet engines in graduate school, but I was given a project to predict the noise from engines so I ended up learning all this stuff about noise. Also I really like music (especially loud music) so it was a good match.

[ Stephen/Ames - 59 - 10:43:06 ]
RE: [Carl/homeschooled] I know the vibrations expert who worked on the Comanche. In testing they found its 5 blade rotor is very quiet at medium speeds.
I worked a bit with helicopter noise a few years ago. 5 blades are quieter than 4 blades because there is less lift on each blade and the lift creates the noise. Of course now you have a heavier helicopter with less payload. It's always a compromise in aerospace engineering.

[ Stephen/Ames - 62 - 10:44:37 ]
RE: [Karen-Karen/BigforkElementary] When you were in elementary school did you do a science fair project? If so what was it about?
No, I never did. I wish I had. Incidentally, I am judging a science fair tomorrow. If you're in to science it is a good way to learn how we do things.

[ Stephen/Ames - 65 - 10:46:34 ]
RE: [Mike-Deborah/YpsilantiCOPE] Is the research you're doing also conducted in other countries?
Yes it is. In fact the Europeans are major competitors...and friends. I once visited the German-Dutch wind tunnel in the Netherlands and they were doing the same kind of work.

[ Stephen/Ames - 67 - 10:48:09 ]
RE: [Brenda-Deborah/YpsilantiCOPE] Has your research affected your hearing?
No, we are very careful about our hearing because we know what damage can be done. We always wear ear plugs.

[ Stephen/Ames - 69 - 10:50:40 ]
RE: [Rachael-Rachael/LangstonHughesMiddle] How many years of high school and college math did you take? What kinds of courses
Lots of math. I liked math when I was in school. I took math every year through high school. I took calculus when I was a senior. In college I took differential equations, partial differential equations, linear algebra...and so forth. Math is the language of engineering so you can't do without it.

[ Susan/NASAChatHost - 70 - 10:50:46 ]
RE: [Rachael-Rachael/LangstonHughesMiddle] What type of classes did you take to help with your oral/written communication skills? Please answer some of my questions because I couldn't get on line and I have a paper due on Friday! Thank you SO much!!
Rachel, I'm sure Stephen is typing as fast he can.

[ Stephen/Ames - 72 - 10:51:29 ]
RE: [Rachael-Rachael/LangstonHughesMiddle] What special talents do you think are helpful for your profession?
Curiosity and imagination will get you far in this business.

[ Stephen/Ames - 74 - 10:52:49 ]
RE: [Rachael-Rachael/LangstonHughesMiddle] since you are a pilot did you ever want to be an astronaut?
Yes I wanted to be an astronaut and I was going to apply last year but I found out my eyesight (20/400) disqualified me. Bummer. 8-( I see just fine down here on earth with my contact lenses.

[ Susan/NASAChatHost - 76 - 10:53:35 ]
RE: [Deborah/YpsilantiCOPE] We need to sign off now. Thank you very much.
Good Bye YpsilantiCOPE, your questions were fabulous! Come back!

[ Stephen/Ames - 78 - 10:54:50 ]
RE: [Rachael-Rachael/LangstonHughesMiddle] What type of classes did you take to help with your oral/written communication skills? Please answer some of my questions because I couldn't get on line and I have a paper due on Friday! Thank you SO much!!
English! Debate! History. Any chance to write a paper or give an oral presentation should be pursued vigorously.

[ Stephen/Ames - 80 - 10:55:07 ]
RE: [Rachael-Rachael/LangstonHughesMiddle] What is your cat's name?

[ Stephen/Ames - 82 - 10:56:09 ]
RE: [Rachael-Rachael/LangstonHughesMiddle] What advice can you give to someone like me who would like to work for NASA?
Be patient and never give up. Jobs are scarce here but the do come up every once in a while.

[ Stephen/Ames - 84 - 10:56:53 ]
RE: [Rachael-Rachael/LangstonHughesMiddle] Do you think there is job security working for NASA?
Usually there has been but things are getting scary lately with budget cuts and all. It's more secure than industry.

[ Stephen/Ames - 88 - 10:57:46 ]
RE: [Rachael-Rachael/LangstonHughesMiddle] How do astronauts sit on top of rockets without going deaf?
I don't know. It must be loud in there. maybe they wear ear plugs or they have acoustic insulation in the shuttle.

[ Carl/homeschooled - 90 - 10:58:30 ]
I think with Bill gates making the big OS computer repair is one of the most secure jobs :)

[ Rachael-Rachael/LangstonHughesMiddle - 91 - 10:58:41 ]
Thank you so much for answering my questions, and don't drink so much coffee!!

[ Stephen/Ames - 93 - 10:59:17 ]
RE: [Rachael-Rachael/LangstonHughesMiddle] Since some work is with people from other countries, do you know other languages?
They usually speak English. English is the language of engineering these days but I have learned a little bit of Spanish and German.

[ Stephen/Ames - 95 - 11:01:36 ]
RE: [Rachael-Rachael/LangstonHughesMiddle] What is your favorite part of history?
I like reading about what they great minds of science were doing back then. Like Leonardo Da Vinci, Edison and Madame Curie. I'm fascinated by how they came up with all those great ideas.

[ Stephen/Ames - 96 - 11:02:06 ]
RE: [Rachael-Rachael/LangstonHughesMiddle] What is your highest degree held in? And, what are you studying now?
I have a masters degree in Aerospace Engineering. Iam working on a PhD.

[ Stephen/Ames - 97 - 11:02:54 ]
RE: [Rachael-Rachael/LangstonHughesMiddle] How many computer classes have you taken?
I learned FORTRAN and BASIC. I took a C class a couple of years ago.

[ Stephen/Ames - 99 - 11:03:33 ]
RE: [Rachael-Rachael/LangstonHughesMiddle] Yes, I did read his bio. In fact it is sitting right next to me. Sorry.
No problema

[ Susan/NASAChatHost - 100 - 11:04:21 ]
RE: [Rachael-Rachael/LangstonHughesMiddle] Yes, I did read his bio. In fact it is sitting right next to me. Sorry.
Well I'm glad. If you write a paper about Stephen send it to us and we'll put it online.

[ Stephen/Ames - 103 - 11:06:36 ]
RE: [Rachael-Rachael/LangstonHughesMiddle] is there any noise in space?
This is a good question! It always irritates me that they have all those loud explosions in Star Trek. THERE IS NO SOUND IN SPACE

[ Stephen/Ames - 105 - 11:07:38 ]
RE: [Carl/homeschooled] Have you ever worked on making jet engins quieter?
Yes, I have worked with jet engines. We measured the noise of a supersonic air liner engine in the 40x80.

[ Stephen/Ames - 111 - 11:12:32 ]
RE: [Rachael-Rachael/LangstonHughesMiddle] Did you always think that math was funny and easy? I think it is hard work.
It IS hard work. But the things that are worth studying are hard. the payoffs are worth it.

[ Susan/NASAChatHost - 106 - 11:07:54 ]
RE: [Carl/homeschooled] Thanks for the answers. I hope all aircraft become soundless... then we can work on leaf blowers
Thanks Carl you add a great deal to our chats!

[ Stephen/Ames - 109 - 11:09:50 ]
RE: [Susan/NASAChatHost] Thank you Stephen you did a great job! I know we all learned a lot!
Thank you very much. You guys are really sharp! Keep up the good work.


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