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ADTO # 79 - September 24, 1999

PART 1: Upcoming Chats
PART 2: Tracking the Vortex


UPCOMING CHATS



QuestChats require pre-registration. Unless otherwise noted, registration
is at:  http://quest.arc.nasa.gov/aero/chats/#chatting

Join us for a special series of chats focusing on the HSCT!

The passenger jet of the future is taking shape! NASA and a team of U.S.
aerospace companies have developed a concept for a next-generation
supersonic passenger jet -- the High Speed Civil Transport (HSCT). The
HSCT would fly 300 passengers at more than 1,500 miles per hour - more
than twice the speed of sound!

Technology to make the HSCT possible is being developed as part of NASA's
High-Speed Research (HSR) program, which began in 1990. The HSCT is
expected to cross the Pacific or Atlantic in less than half the time of
modern subsonic jets. The HSCT is expected to make its debut in 2015. More
about the High Speed Civil Transport at
http://quest.arc.nasa.gov/aero/events/hsct.html


Tuesday, September 28, 1999, 10 AM Pacific Daylight Time:
Mina Cappuccio, aerospace engineer

Mina Cappuccio was the focal or Lead Researcher for the Wind Tunnel Test
of the High Speed Civil Transport Model! Even though she's busy working
with all the data from the test she is giving us the opportunity chat.
Please join us bring your questions about this test and the airliner of
the future!


Read Mina Cappuccio's profile prior to joining this chat.
http://quest.arc.nasa.gov/aero/team/cappuccio.html


Tuesday, October 5, 1999, 10 AM Pacific Daylight Time:
Linda Bangert, aerospace technologist

Linda tests airplane models in wind tunnels and simulates jet
engine exhaust using high pressure air. The results of these tests help
her understand how propulsion may affect certain aircraft designs. In
addition to supporting testing for military aircraft, Linda
also tests designs for future supersonic passenger airlines during take
off and landing speeds (about 180 miles per hour).
 

Read Linda Bangert's profile and field journals prior to joining this
chat. http://quest.arc.nasa.gov/women/bios/lsb.html


[Editor's Note: Mina Cappuccio has been the focal or the lead researcher on the wind tunnel test of the high speed civil transport. Read her biography and journals at http://quest.arc.nasa.gov/aero/team/cappuccio.html ]

Tracking the Vortex

By Mina Cappuccio

September 3, 1999

We switched over to the mid-mount canard since my last journal. We ran
with the mid-mount canard. We were mostly running stability and control
data runs. That means we ran Alpha sweeps at a constant Side Slip angle
for different canard angles and side slip angle sweeps at a constant alpha
for different canard angles. This was done with different canard
elevators. We tested with the vertical tail on and off and with the
horizontal tail on and off. We did a bunch of rudder effectiveness runs
where we had to change the rudder on the tail to different angles. This
test was to check if the rudder was affected by a vortex caused by the
mid-mount canard.

We finished running with the mid-mount canard on Friday, and we were
hoping to start the smoke visualization, but the equipment wasn't ready.
Saturday we did three or four more runs with the mid-mount canard, and
then we switched over to the high-mount canard. We finished up some of our
runs, and then we were ready to do the smoke visualization.

Meanwhile, Monday and Tuesday, the smoke Vis cameras and laser system was
being fine tuned. On Tuesday, we finally did the laser smoke screen
visualization. They turned on their system. We did a few test runs. We
were able to trace the vortex, but it was hard to see because the lenses
on the cameras lacked zoom capability. So we had to come down and
replace the lenses. Then we had a lot of trouble with backscatter, or too
much light. When you run the laser system you shut off all the lights, and
we painted the model black so that we wouldn't get any reflection off the
model. Having the cameras on the same side of the tunnel as the laser
didn't work. Because of the angles of the cameras and the way the
laser was pointing there was too much light scatter. You couldn't see
anything but light. This required that the cameras be moved to the other
side. They mounted the cameras high so that they would still look down on
the side of the model that was painted black. That helped, but the
fuselage was creating a shadow on part of the wing. Finally, we got it to
work so that we could trace the vortices.

We saw two vortices that were coming off the leading edge of the wing and
going underneath the surface of the wing at low angles of attack. When we
pitched the model up to a higher angle of attack the vortices went over
the wing. The third vortex we saw was the one that came off the canard
tip. That was really hard to do. One problem was the angle of the camera
relative to the laser beam, and the other problem was the white walls of
the wind tunnel. There was so much reflection of the laser beam light off
the white walls and into the camera.

The smoke is special, it has tiny molecules. What we really see is the
core, or the void, of the vortex. When we looked at the television monitor
where the camera signal is coming in, what we saw were these black dots.
The black dots indicated the void of the vortex, and we had to use the
zoom lenses on the cameras to find them. Sure enough those black dots were
the void of the vortices. You could track it by moving the laser light
sheet. You could see where the vortex started and how it progressed
downstream. The vortices coming off the wings were beautiful, you could
see very large holes, but the one that was coming off the canard had a
very small hole. So we changed the lens on the camera to get more zoom
capability and then we went back in and ran again. We traced it from the
canard and traced it off the canard. You could see the void starting, and
then you could follow it over the wing surface and by the vertical tail.
This was the predicted result.

Then we were told that the last day of our test was next Friday. We
thought we had reserved the tunnel until the middle of next week. We
started getting nervous because the smoke visualization was taking time.
Mike Elsey from Boeing was getting nervous because we needed to complete
the force data runs. So we only got one flow visualization run in and that
was it. That was disappointing.
 
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