[ Susan/NASAChatHost - 6 - 10:05:09 ]
RE: [Carl/homeschooled] Good morning (afternoon) Susan!
Carl you must be in the eastern time zone

[ Susan/NASAChatHost - 7 - 10:05:43 ]
Who funds your research?

[ Larry/AmesResearchCenter - 9 - 10:07:07 ]
It is all funded by NASA. Some projects are funded by the FAA and DOD as well.

[ Carl/homeschooled - 8 - 10:06:47 ]
hmm dual rotors on a vertical take off aircraft would have to be going in opposit directions to keep the aircraft from spining... I wonder what that kind of turbulence does to the lift when its in normal forward flight

[ Larry/AmesResearchCenter - 10 - 10:08:42 ]
Hi Carl. You're right about the rotors going in opposite direction. Turbulence (buffetting) is a problem.

[ Larry/AmesResearchCenter - 12 - 10:13:44 ]
RE: [Susan/NASAChatHost] Larry have you ever flown in a tiltrotor?
No, mores the pity. I've flown a number of helicopters but the only existing tiltrotors are research or pre-production aircraft and very few people get to fly in those -- so far. But, I'll definitely be one of the first to buy a ticket when we all can.

[ Larry/AmesResearchCenter - 15 - 10:21:02 ]
RE: [Alex-Alex/homeschool] Hi. Sorry I'm late. I had to do some school work, and then read your biography. When I saw you in that picture, it looked like you are Asian. Are you? (I am.) I have a lot of the same interests as you did when you were young. My three most favorite interests are coin collecting, high flying supersonic planes, and virtual flight simulators.
No, I not Asian -- a small part native-american, though. Coin collecting is neat. Do you do it as an 'investment' or mostly for fun. airplanes and simulators are neat too but I was more into robots and mechanical gizmos when I grew up.

[ Larry/AmesResearchCenter - 19 - 10:25:02 ]
RE: [Alex-Alex/homeschool] I know about one tiltroter, and it's being used in the Navy. Are there other ones, and what are their names?
The Navy/Marine tiltrotor is called the V-22 Osprey it will soon be going into full production. It is primarily a troop transport (~30 troops with 4 crew). The other tiltrotors still flying are the XV-15 research aircraft (no name) and the 'eagle-eye' RPV. Bell-Boeing is the only 'company' making tiltrotors currently and they have plans to come out with a civilian (6-9 passengers) tiltrotor called the 609.

[ Larry/AmesResearchCenter - 21 - 10:27:06 ]
RE: [Sarah-Sasrah/Greenmeadow] Are you planning any wind tunnel tests?
Yes I am. Members of my team just completed a test in the DNW windtunnel in the Netherlands in Dec. We will be going back there in April and May. Also, after this test there will tests in the National Full-Scale Aerodynamics Complex in a couple of years with the TRAM.

[ Larry/AmesResearchCenter - 23 - 10:30:00 ]
RE: [Carl/homeschooled] Larry why don't you pay Sikorski to make you a quiet rotor they made the comanche as good as silent.
Sikorsky is actually working jointly with NASA and the other helicopter manufacturers to develop low noise proprotors for tiltrotors. This done as a part of large project/program called the Short Haul Civil Tiltrotor program. The Comanche has five blades in its rotor that how it is quieter. Proprotors will likely have higher number blades in the future too -- though this mechanically hard to build.

[ Larry/AmesResearchCenter - 24 - 10:32:28 ]
RE: [Sarah-Sasrah/Greenmeadow] Do you have to study the results of your last test first or will the next test study something different?
The first test was mostly as system checkout test. The second test entry is to acquire the research quality data. However, we are quickly scrambling to look at the data from the first test. However, most wind tunnels are booked (you have to make reservations) well in advance and so we have to meet our schedule or lose our tunnel slot.

[ Carl/homeschooled - 26 - 10:35:37 ]
It has to do with the way the rotors move the air. More rotors move the air continuasly and les rotors kindof let the air slow down and speed up.

[ Larry/AmesResearchCenter - 27 - 10:36:31 ]
RE: [Alex-Alex/homeschool] I do my coin collecting just for fun, and my save my most valuable coins to use for college. I am interested in robots and mechanical gizmos the same as I am interested in planes! There all very interesting, but CIA spy planes would probably be my most favorite.
Yeah, the CIA and DOD get to do great stuff in their 'black' programs -- though it takes years for us to find out most of the time. If you haven't seen Aviation Week magazine before you should get hold of copies. They are often times the ones who break the news when programs become declassified (or have good rumors).

[ Sarah-Sasrah/Greenmeadow - 28 - 10:37:22 ]
So air moving continuously is quieter?

[ Larry/AmesResearchCenter - 32 - 10:41:32 ]
RE: [Sarah-Sasrah/Greenmeadow] Wow! I never thought more rotors would make a helicopter quieter, can you say something more about why that is?
It still has to be definitively proven that more blades make a helicopter/tiltrotor quieter in general -- but it is a likely approach for low noise rotors. The reason why more blades are likely to make tiltrotors quieter is for two reasons: 1. blades tips shed off vortices like plane wings do (just in helical patterns instead of straight back) and the more blades (for a given rotor thrust/lift) the weaker the vortices; 2. the weaker the vortices the less strong the pressure pulse on the next blade when it collides with the proceeding blades trailed vortex.

[ Larry/AmesResearchCenter - 34 - 10:43:18 ]
RE: [Carl/homeschooled] when the rotors are moving past the speed of soud at the ends yes :)
No, helicopter/tiltrotor blades operate in the transonic region tip Mach of 0.6-0.8 typically. (Mach of 1.o is the speed of sound.)

[ Larry/AmesResearchCenter - 36 - 10:46:11 ]
RE: [Alex-Alex/homeschool] Did you become interested in the tiltroter when NASA told you about the job you have, or were you interested in it before then or in college?
No, though I read about some of NASA's vertical lift technology when I was growing up I never heard of them until I started working at Ames. I first started working on conceptual design/advanced technology work for rotorcraft when I first started working at Ames. My first tiltrotor work was in 84.

[ Larry/AmesResearchCenter - 38 - 10:48:32 ]
RE: [Susan/NASAChatHost] Larry, I am interested that you use a wind tunnel in the Netherlands what are the advantages? availability?
The Army and NASA have had a long working relationship with the DNW tunnel (since the late 70's when it was built). But mostly it is because of tunnel availability. The NFAC (the 40-by-80 and 80-by-120 tunnels) are being upgraded currently so we couldn't test at 'home.'

[ Larry/AmesResearchCenter - 40 - 10:51:39 ]
RE: [Alex-Alex/homeschool] When you read the Aviation Week magazine, were there interesting planes that the government declassified? If so, what are their names, how fast can they fly, and how high can they fly? Are there any internet sites on them?
There are rumors of a plane called 'Auroa' (sp?) in the early 90's. But I haven't heard anything recently. The military is really looking at (remotely piloted vehicles) RPV 'fighter' type of aircraft right now in a big way.

[ Larry/AmesResearchCenter - 41 - 10:53:48 ]
RE: [Sarah-Sasrah/Greenmeadow] Wow! Thanks Larry and Carl I think I am getting the idea do you know about any CFT pictures of the vortices? What is helical?
I think the Aero Design Online web page may show some. But maybe I can talk to Susan getting some pictures on there if there aren't any. Helical means in the shape of a 'spring.' Think Slinky (TM).

[ Sarah-Sasrah/Greenmeadow - 43 - 10:55:51 ]
Thanks for the answers! I learned a lot, we have lunch now, I'll look for those pictures

[ Larry/AmesResearchCenter - 44 - 10:56:14 ]
RE: [Sarah-Sasrah/Greenmeadow] I was thinking that you would make the tiltrotor quieter by muffling the engine or something.
Engine noise is important. But the rotors/proprotors make the most noise. That is why making them quieter is so hard. Regular jets noise is almost all engine noise. Not so rotorcraft. The physics of rotorcraft is very complex and not even fully understood even today.

[ Larry/AmesResearchCenter - 45 - 10:58:18 ]
RE: [Alex-Alex/homeschool] What is your favorite plane?
I like the Tomcat for fighter aircraft. I like the sikorsky S-76 for helicopters. (MY personal opinion not an endorsement) And I am very excited about tiltrotors.

[ Larry/AmesResearchCenter - 46 - 11:00:39 ]
RE: [Sarah-Sasrah/Greenmeadow] How are they improving the NFAC tunnel?
They completely removed the 'test section' in the 40-by and are replacing it with a new section to have better acoustic properties to make it a better place to make noise measurements. They are almost done but it took over three years.

[ Alex-Alex/homeschool - 48 - 11:02:32 ]
I like the Tomcat a whole lot, too. It is my favorite fighter plane, and the P51-D. I like the Tomcat because its maximum speed is 1,584 mph at 40,000 ft. It can engage more planes and from farther distances than the F-4, F-15 and F-18.

[ Susan/NASAChatHost - 49 - 11:03:50 ]
RE: [Carl/homeschooled] Well Im of to do more school work thanks for the answers Larry...
Bye Carl!!

[ Larry/AmesResearchCenter - 50 - 11:05:20 ]
RE: [Alex-Alex/homeschool] I like the Tomcat a whole lot, too. It is my favorite fighter plane, and the P51-D. I like the Tomcat because its maximum speed is 1,584 mph at 40,000 ft. It can engage more planes and from farther distances than the F-4, F-15 and F-18.
Don't forget to check out rotorcraft from now on, Alex. They can be fun, exciting, and interesting too. Keep up those hobbies.

[ Alex-Alex/homeschool - 51 - 11:06:07 ]
Bye Larry. One more reason why I like the fighter jet is because it carries one of the most expensive missles and farthest flying missle. That missle is AIM-54 Phoenix.

[ Susan/NASAChatHost - 52 - 11:06:26 ]
Thanks everyone this has been a great chat! I have learned a lot!Thanks so much Larry!