- 5 - 10:04:38 ]
RE: [Susan/NASAChatHost] Good morning Larry, what are you
working on now?
Mostly working on budget issues for my project.
- 6 - 10:05:09 ]
RE: [Carl/homeschooled] Good morning (afternoon)
Carl you must be in the eastern time zone
- 7 - 10:05:43 ]
Who funds your research?
- 9 - 10:07:07 ]
It is all funded by NASA. Some projects are funded by the FAA and DOD
[ 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
- 10 - 10:08:42 ]
Hi Carl. You're right about the rotors going in opposite direction. Turbulence
(buffetting) is a problem.
- 12 - 10:13:44 ]
RE: [Susan/NASAChatHost] Larry have you ever flown in a
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.
- 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.
- 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.
- 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.
- 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
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.
- 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
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
- 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?
- 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.
- 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.)
- 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.
- 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.'
- 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.
- 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
- 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.
- 45 - 10:58:18 ]
RE: [Alex-Alex/homeschool] What is your favorite
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.
- 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.
- 49 - 11:03:50 ]
RE: [Carl/homeschooled] Well Im of to do more
school work thanks for the answers Larry...
- 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.
- 52 - 11:06:26 ]
Thanks everyone this has been a great chat! I have learned a lot!Thanks
so much Larry!