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[music playing]

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Welcome to the 2015
NASA Ames Summer Series.

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The world around us
contains materials

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that can be divided
into solids, liquid, and gas.

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These descriptions
of the state of matter

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are relative to the particular
time span being observed.

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Given a long enough time,

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all matter
exhibits fluid motion.

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Understanding the interactions

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between these different
states of matter

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is important for optimization
of design and function,

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specifically when you
talk about work

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that is done in aeronautics
and space travels.

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Today's seminar is
"It's a Fluid World"

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and will be presented
by Christina Ngo.

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Christina received
her Bachelors of Science

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in mechanical engineering

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with a concentration
in aerospace

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from the University of
California, San Diego in 2013,

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but prior to that,
she was also here at Ames

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as an intern in 2009.

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So all the interns
that are in the audience,

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think of the future.

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After doing the internship,
she got experiences

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both in work and as an intern
in aeronautics

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at Pratt & Whitney, at
Hamilton Sundstrand, and SpaceX.

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And then she decided
to come back to Ames.

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So she joined
the Fluid Mechanics Lab

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as a research engineer

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two years ago
as a full-time employee.

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And so please join me
in welcoming Christina Ngo.

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[applause]

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Hello.

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My name is Christina Ngo,

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part of
the Fluid Mechanics branch.

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[clears throat]

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Today I'll be presenting
"It's a Fluid World."

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So about six years ago,
like Jacob mentioned,

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I was sitting exactly where
you are sitting as an intern

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and thought to myself, "Man,

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it would be great one day
if I could ever be up there."

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And honestly, I never thought I
would ever have the opportunity.

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So word of advice to all the
interns who are out there today,

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work hard,
ask questions, learn a lot.

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You're surrounded
by some amazing people.

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Really take advantage
of your internship.

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So let's begin.

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So, during this talk,

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I'm going to show you
some of the hot research topics

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that we have that we've done
in our branch

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currently and in the past

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as well as how the aerodynamics
applies to the world around us.

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Here you see a lot
of interesting photo.

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It's basically a collage
of a lot of the research topics

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that we've done in the past,

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anywhere from space shuttles
to rockets to even sports balls,

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next generation airplanes.

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For in our branch,
we are investigating the flow

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around our models,
whether that's on the surface

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or off the surface of the model.

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So how many of you have heard
of a wind tunnel?

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[chuckles]

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Majority of you, great.

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So, for us to investigate
all these parameters,

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characteristics
of the flow field,

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we have to look at it sometimes
instantaneous in time.

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So it's really difficult
to measure these characteristics

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having, say,
a rocket going up

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several hundred miles per hour
through the atmosphere.

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So, instead of
having air moving--

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having the model
moving over the air,

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we have air moving
over the model,

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which is why we have
wind tunnels.

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There's several of them
shown here.

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Top left, we have the 40x80
wind tunnel

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and next generation
airplanes shown.

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Top right, we're home to
the world's largest wind tunnel.

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We have parachute testing
right over here.

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We even have
smaller scale wind tunnels

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like the 11 feet by 11 feet
transonic wind tunnel

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testing a plane as well
and sports ball aerodynamics.

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Really great things
you need to do,

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and the majority of the research
is done in wind tunnels

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because of this, of course.

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So I talked a little bit
about wind tunnels

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and how we use air
to move over our models,

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but we could actually
use any fluid.

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Here we have a facility
called a water channel,

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so we're moving water
across our model.

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So how does this work?

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Well, we have an upper channel
and a lower channel,

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and the water moves
from the upper channel

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through our test section
back down to a lower channel,

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gets pumped back behind here.

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That's not shown on the photo.

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We're able to put
small scale models in here.

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Once that is done,
we inject this fluorescent dye.

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These green lines that you see,
that's illuminated by UV lights.

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We have a second color dye.

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It's the orange dye
that we use to inject

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in places of interest, say,
in the seat of a convertible

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or behind a sports ball
right over here

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or even behind a hill.

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So it's a really great visual
technique to start,

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instead of using

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really expensive
computational techniques

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or advanced instrumentation
before we even begin testing.

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But what better way
to explain it

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than actually showing you
in action?

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So here you go.

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We have the fluorescent dye
flowing from left to right.

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It's the green dye,

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and we injected the orange dye
in the very back here.

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What's in this test section
is a hill.

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We call it the Fundamental Aero
Investigates The Hill,

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or FAITH Hill.

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What's great about this dye,

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this feature
you can actually see exactly

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where the flow is separating
off the model right over here

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and the vortex shedding
that's coming off of it.

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Even on this hill,
it does look quite simple.

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It's a cosine hill.

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The flow
is actually quite complex,

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and with this hill, we use all
of our experimental technique

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to measure the forces
and pressures on the surface

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and on top of the surface
of the model

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to validate a lot
of our computational method.

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Again, here you can see
how complex the flow

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can actually be.

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See the recirculation area
and the flow behind there,

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it's almost stagnant.

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It's barely moving.

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One technique that we use

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is fringe-imaging skin friction

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to measure the skin friction
on top of our model.

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Here is FAITH Hill again,
and how does this work?

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Well, let me explain
skin friction first.

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Skin friction is the force
that parallels

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the surface of the model.

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So we have a model, and it has
to be shiny for this to work.

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We install this
into a wind tunnel.

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We turn on the wind tunnel
for a certain amount of time.

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Remember to apply oil
of known viscosity.

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Once the wind tunnel runs
for a certain amount of time,

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the oil sort of smears
around our model.

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Once that is done,
we illuminate the model

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with an extended
monochromatic light source.

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You get two interfering
light waves when that happens.

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First the light reflects
off the surface of the model,

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so that's one light wave,
and then second,

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the light reflects
off the surface of the oil.

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That's a second light wave.

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And you get these fringe
patterns that you see here.

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In measuring the direction

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and the space
in the fringe pattern,

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we could actually record that
with skin friction.

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So remember the video
I showed you before

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where the flow starts
separating and speeding up?

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You could see it in here
as well.

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Starts speeding up
and the skin friction increases,

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and once the flow's--

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it's all stagnant and slow
in the very back,

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skin friction is actually
really low right back here.

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Another technique
that our branch excels at

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and spends a lot of time in
is pressure-sensitive paint.

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So originally, normally,
we install our models

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with discrete pressure tap,
or pressure holes,

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like you see here in one of
our crew exploration vehicles,

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Orion.

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These tiny holes
to measure pressure.

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And for us to get a nice
contour surface pressure map,

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we have to extrapolate the data,

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which sometimes could cause
a lot of error here.

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So with
pressure-sensitive paint,

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you pretty much
get a pressure tap--

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a pressure measurement
at every pixel of the picture.

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So you get a whole map

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of the pressure surface
without even extrapolating.

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It's a very powerful technique.

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Well, how does this work?

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This pressure-sensitive paint

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is first painted
on top of the model.

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It's this nice pink color here.

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It's pretty cute here,

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and there's these molecules
inside the paint

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that are excited by UV lights.

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For them to return back
to the base state

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is via oxygen quenching,
which is great,

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because the higher pressure
you have on the surface,

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the more oxygen there is;

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therefore they're more quenching

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and the less luminescence
that's picked up by our cameras.

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And we can correlate this
with pressure to give us

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a nice contour map
that you see on the right.

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A few examples I have is
on a space shuttle

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right over here going Mach 2.5.

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So Mach 1 is the speed of sound.

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Right now it's 2.5 times
the speed of sound.

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On the bottom right,
you see an F-18 going Mach 1.25.

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Another great advantage
of pressure-sensitive paint

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is you're able to paint surfaces
where you probably couldn't--

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an instrument, say,
where the wing attaches

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to the body or the tip
of the nose, right?

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Here is a video
of changing angles of attack

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of an F-16 model.

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You can see
how the pressure is changing.

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Say, if I'm running
a computational method

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to see the surface pressure

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only at angles zero
and one or two degrees,

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how would I know
at the higher angles of attack

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to install pressure tap
right here,

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and that's actually
an area of interest?

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You wouldn't.

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But with
pressure-sensitive paint,

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you don't need to do that.

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So we talked a lot
about pressures and forces

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on the surface of the model.

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How about off of the model?

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The flow field
off the top of the model?

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Well, we use a lot
of optics technique.

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One technique we use is particle
image velocimetry seen here.

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We use a laser that's shining
into a circular mirror

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and produces this laser sheet

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right across the model
in our wind tunnel.

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We need windows for this, right?

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Right over here.

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And using pulse LED lights
and two cameras

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and injecting, say, smoke or
known particles into the flow,

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we're able to track
these particles

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through the laser sheet.

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So we know DP,
the position,

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and the time it took for it
to move to that position;

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therefore, we know velocity.

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Three components of velocity.

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This is a very powerful tool

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to validate, say,
computational codes

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or looking at turbulence models.

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For the aero engineers
out there,

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you can even see bow shock

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coming off of the shuttle
right over here

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starting this really big jump
in velocity.

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But why stop there?

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How about we take
a multiple image

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to get a nice video
that varies in space and time?

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So here on the top
is the still image of a cylinder

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with smoke injected
into a flow field.

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You get this vortex shedding.

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Same thing as down here
but using PIV.

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We have a cylinder
right up here,

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and you see the vortex shedding
moving back and forth

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right over here.

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It's two out of the three
components of velocity plotted.

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Another imaging technique
we use is called Schlieren.

254
00:11:08,360 --> 00:11:09,870
So usually we use air
in our wind tunnel,

255
00:11:11,240 --> 00:11:12,660
and once
you start approaching, say,

256
00:11:12,840 --> 00:11:15,210
the speed of sound, Mach 1,
air starts getting compressed.

257
00:11:16,120 --> 00:11:18,390
When air starts getting
compressed, the density changes.

258
00:11:18,750 --> 00:11:20,750
So using LED light source
and high-speed cameras,

259
00:11:22,090 --> 00:11:23,480
we can measure
the refractive index

260
00:11:24,270 --> 00:11:25,540
of how the light
is reflected off

261
00:11:26,570 --> 00:11:29,060
through the density gradient
and take this really nice image.

262
00:11:30,720 --> 00:11:32,000
Right here we have a rigid model

263
00:11:32,150 --> 00:11:34,210
of a Mars Science Lab parachute
going about Mach 2.5,

264
00:11:36,330 --> 00:11:38,660
where it's extremely evident
where the density is changing

265
00:11:38,780 --> 00:11:39,780
is around shocks.

266
00:11:40,600 --> 00:11:42,420
And you can see a nice bow shock
right over here

267
00:11:42,510 --> 00:11:45,660
dancing around
in front of our model.

268
00:11:48,300 --> 00:11:49,690
Okay.

269
00:11:50,690 --> 00:11:51,690
On with imaging.

270
00:11:52,360 --> 00:11:54,480
So one test that we've done
is to look at just the plumes

271
00:11:57,240 --> 00:11:58,240
and take a nice image

272
00:11:58,780 --> 00:12:00,420
and see the details
of what's going on.

273
00:12:01,030 --> 00:12:03,090
Normally, we have a picture
like this on the top left.

274
00:12:03,570 --> 00:12:05,750
It's really saturated, and a lot
of the details are lost.

275
00:12:06,630 --> 00:12:08,360
How about, what if
we had different cameras

276
00:12:10,150 --> 00:12:12,150
around the same location
with different filters?

277
00:12:12,150 --> 00:12:13,780
We're able to superimpose
these filters--

278
00:12:14,150 --> 00:12:15,150
these photos together,

279
00:12:15,600 --> 00:12:17,780
each having a little bit of--
the last photo didn't have,

280
00:12:19,420 --> 00:12:21,660
little bit of pieces of areas
that we couldn't get before,

281
00:12:24,030 --> 00:12:25,149
and superimpose them together

282
00:12:25,150 --> 00:12:28,360
to get a really nice photo
like this here.

283
00:12:31,810 --> 00:12:33,630
So we used this technique
at a shuttle launch.

284
00:12:34,210 --> 00:12:35,210
What better way to use it?

285
00:12:36,060 --> 00:12:38,210
Right here we have the 2011
last, final shuttle launch.

286
00:12:39,810 --> 00:12:41,000
On the left is a normal photo.

287
00:12:41,870 --> 00:12:43,060
Keep in mind the right photo,

288
00:12:43,720 --> 00:12:45,510
we used five cameras
with different filters

289
00:12:45,600 --> 00:12:46,600
and one IR camera,

290
00:12:47,210 --> 00:12:49,150
or infrared camera,
that measures temperature.

291
00:12:50,870 --> 00:12:52,030
So this part right over here

292
00:12:53,720 --> 00:12:55,209
you could see
with the different filters,

293
00:12:55,210 --> 00:12:56,210
but with this part

294
00:12:56,300 --> 00:12:57,600
on the shuttle
that's coming off,

295
00:12:58,150 --> 00:13:00,120
none of the filters
would actually pick that up.

296
00:13:00,240 --> 00:13:02,360
That is because we had an
IR camera on this part as well.

297
00:13:04,090 --> 00:13:05,419
The second thing
that's also really great--

298
00:13:05,420 --> 00:13:07,179
looking at debris
that's coming off of the model

299
00:13:07,180 --> 00:13:08,720
that we couldn't see
in normal pictures.

300
00:13:10,420 --> 00:13:11,570
But using the same technique,

301
00:13:12,510 --> 00:13:14,660
we are actually able to produce
really nice videos too,

302
00:13:15,150 --> 00:13:16,210
and I'll show you right now.

303
00:13:19,120 --> 00:13:22,120
[rocket engines firing]

304
00:13:29,570 --> 00:13:31,180
(Christina)
You can see all the details

305
00:13:31,240 --> 00:13:33,300
that we never could have seen
without this technique

306
00:13:36,390 --> 00:13:38,240
and even little debris
that might be coming off

307
00:13:39,120 --> 00:13:41,180
we could definitely detect
in this better than this.

308
00:13:41,780 --> 00:13:43,780
[man speaks indistinctly
on video]

309
00:13:47,180 --> 00:13:49,330
Pretty amazing.

310
00:13:51,870 --> 00:13:54,210
So one big project that we've
done in the last couple years

311
00:13:55,840 --> 00:13:57,750
was the crew exploration
vehicle launch abort.

312
00:13:59,060 --> 00:14:00,510
So in this scenario,
it only happens

313
00:14:00,780 --> 00:14:03,270
during an emergency abort where
we have to take our astronauts

314
00:14:03,600 --> 00:14:05,090
off the rocket
and back home safely.

315
00:14:06,120 --> 00:14:07,270
And many aerodynamic aspects

316
00:14:08,660 --> 00:14:10,480
that we need to consider
during this mission.

317
00:14:12,510 --> 00:14:13,510
Here we have Orion capsule

318
00:14:14,660 --> 00:14:16,360
painted with
pressure-sensitive paint,

319
00:14:17,480 --> 00:14:19,600
and we have a simulation
of a rocket right behind here.

320
00:14:21,180 --> 00:14:22,810
So we separate the capsule
from the rocket,

321
00:14:24,330 --> 00:14:26,209
and we could look at
to see the density gradients

322
00:14:26,210 --> 00:14:28,030
and the shocks
and the aerodynamic variation

323
00:14:28,690 --> 00:14:29,690
during that separation.

324
00:14:30,480 --> 00:14:32,840
Secondly, we're concerned about
the abort motors right here

325
00:14:34,270 --> 00:14:36,600
using high-pressure air to
simulate an abort motor exhaust

326
00:14:36,690 --> 00:14:38,390
impinging onto the surface
of the rocket,

327
00:14:39,270 --> 00:14:41,750
whether that be forces, moments,
pressures, or even acoustics.

328
00:14:44,420 --> 00:14:46,420
On the right, you have a bunch
of Schlieren photos.

329
00:14:47,450 --> 00:14:49,630
You could see the density
gradients are right over here.

330
00:14:49,690 --> 00:14:51,720
They're usually shocks
and a nice shock in the front

331
00:14:52,540 --> 00:14:53,540
of the model over here

332
00:14:54,330 --> 00:14:55,480
and a second shock right here.

333
00:14:57,480 --> 00:14:58,480
So why is this important?

334
00:14:59,030 --> 00:15:00,450
Well,
where do the astronauts sit?

335
00:15:00,780 --> 00:15:01,780
They sit right here,

336
00:15:02,600 --> 00:15:04,000
so we need to understand
very well

337
00:15:04,690 --> 00:15:07,840
what is happening
during this process.

338
00:15:10,480 --> 00:15:12,270
Here's a Schlieren photo
of the separation,

339
00:15:13,210 --> 00:15:14,840
and you can see
the rapid changes in density

340
00:15:16,630 --> 00:15:18,810
and how dynamic the environment
is during this portion.

341
00:15:20,780 --> 00:15:23,000
So the crew capsule is removing
itself from the rocket

342
00:15:23,540 --> 00:15:24,540
at about 10 Gs.

343
00:15:25,120 --> 00:15:27,060
That's incredibly fast
and incredibly dynamic,

344
00:15:27,300 --> 00:15:28,390
and a lot of force is going on.

345
00:15:32,000 --> 00:15:33,420
Here is a second video
of impingement

346
00:15:34,870 --> 00:15:36,870
using high-pressure air
to simulate the exhaust.

347
00:15:37,540 --> 00:15:39,390
One interesting feature
to point on this photo

348
00:15:39,480 --> 00:15:41,480
is you could see these
multiple shocks coming off,

349
00:15:41,660 --> 00:15:42,660
converging into one,

350
00:15:43,720 --> 00:15:45,180
as well as
the exhaust interaction

351
00:15:45,300 --> 00:15:46,300
with the second shock,

352
00:15:46,570 --> 00:15:48,360
you see a crossover
coming over here as well.

353
00:15:50,600 --> 00:15:52,210
And we talked a little
about acoustics,

354
00:15:52,420 --> 00:15:54,330
but how do you look
at acoustics data using this?

355
00:15:55,720 --> 00:15:57,180
Well, we have
a whole research team

356
00:15:58,360 --> 00:15:59,510
dedicated to aeroacoustics.

357
00:16:01,750 --> 00:16:02,750
On the top right,

358
00:16:03,120 --> 00:16:04,750
you have a 26% scale
of a 777 wing right here.

359
00:16:07,630 --> 00:16:09,540
And right here,
you have these acoustics array.

360
00:16:10,810 --> 00:16:13,360
There's usually several dozen
to a couple hundred microphones

361
00:16:14,300 --> 00:16:16,300
in a predetermined pattern
measuring this noise.

362
00:16:17,330 --> 00:16:19,570
With this technique, we're able
to measure the magnitude

363
00:16:20,540 --> 00:16:21,690
and the location of the noise,

364
00:16:23,060 --> 00:16:24,360
so I would call it
a sound picture.

365
00:16:24,870 --> 00:16:27,330
Once that picture is taken,
you can superimpose this picture

366
00:16:27,390 --> 00:16:28,870
on the surface
of the model, say, here.

367
00:16:30,840 --> 00:16:32,089
Right now you can see
a lot of the noise

368
00:16:32,090 --> 00:16:33,630
coming from the leading edge,
the slats,

369
00:16:34,210 --> 00:16:36,210
and from the trailing edge,
the flaps, right here.

370
00:16:37,810 --> 00:16:39,870
Nowadays, engines
are getting quieter and quieter,

371
00:16:40,390 --> 00:16:42,570
so we need to reduce the noise
of the plane itself as well.

372
00:16:43,780 --> 00:16:45,569
I always thought,
when a plane was flying over,

373
00:16:45,570 --> 00:16:46,840
it was all
from the engine noise,

374
00:16:47,810 --> 00:16:48,810
but it really isn't.

375
00:16:50,180 --> 00:16:51,660
A huge amount of noise
also comes from,

376
00:16:52,000 --> 00:16:53,000
like, the landing gear.

377
00:16:53,570 --> 00:16:55,090
Basically anything
with a sharp edge

378
00:16:55,210 --> 00:16:56,210
produces a lot of noise.

379
00:16:57,750 --> 00:16:59,060
On the bottom right
right here,

380
00:16:59,480 --> 00:17:01,330
it's something
called an anechoic chamber.

381
00:17:02,360 --> 00:17:03,720
It's what we use
to build our arrays

382
00:17:04,780 --> 00:17:06,060
and do some sound experiments.

383
00:17:08,210 --> 00:17:09,630
So what this chamber does
is the walls

384
00:17:10,210 --> 00:17:12,210
are built up with these wedges
that absorbs noise.

385
00:17:14,510 --> 00:17:15,720
So, if you're testing something

386
00:17:16,030 --> 00:17:17,449
and you want to know
exactly where a noise source

387
00:17:17,450 --> 00:17:19,270
is coming from,
you don't have the reflection

388
00:17:20,750 --> 00:17:22,660
off the walls coming off
and messing up your data

389
00:17:22,810 --> 00:17:23,810
or giving you errors.

390
00:17:24,450 --> 00:17:25,510
So that's what's done here.

391
00:17:26,360 --> 00:17:27,540
The majority of any experiment

392
00:17:28,420 --> 00:17:30,330
that goes up on
the International Space Station

393
00:17:30,630 --> 00:17:32,090
needs a sound
qualification test,

394
00:17:32,810 --> 00:17:36,060
and that's usually done here
in an anechoic chamber.

395
00:17:38,750 --> 00:17:40,660
Here is an example
of our microphones in action.

396
00:17:42,060 --> 00:17:43,570
We have the launch abort mode
full scale

397
00:17:44,270 --> 00:17:46,000
that was tested in Utah
several years back,

398
00:17:46,810 --> 00:17:49,150
and here are the microphones
that's measuring magnitude

399
00:17:49,390 --> 00:17:50,390
in this case.

400
00:17:52,810 --> 00:17:54,600
But a better visualization
of this is seeing

401
00:17:55,570 --> 00:17:57,390
the launch abort motors
actually turning on,

402
00:17:58,810 --> 00:18:00,180
so I have a video
for you as well.

403
00:18:01,480 --> 00:18:04,660
[rocket engine firing]

404
00:18:13,420 --> 00:18:15,480
(Christina)
Imagine how loud
it really actually is

405
00:18:16,180 --> 00:18:17,240
and sitting right above it,

406
00:18:18,840 --> 00:18:20,330
right under it
could be detrimental

407
00:18:21,210 --> 00:18:24,570
if you don't understand
the characteristics of this.

408
00:18:26,210 --> 00:18:27,210
But...

409
00:18:27,390 --> 00:18:29,030
So back in 2013,
we went one step further.

410
00:18:30,660 --> 00:18:32,780
We tested this at a real launch
for the very first time.

411
00:18:34,150 --> 00:18:35,450
So here is
the microphone arrays,

412
00:18:36,810 --> 00:18:38,420
and to give you a scale
of how big this is,

413
00:18:38,540 --> 00:18:39,540
about 10 feet by 10 feet.

414
00:18:40,240 --> 00:18:41,240
It's huge.

415
00:18:41,540 --> 00:18:43,360
Several hundred microphones
are installed,

416
00:18:44,870 --> 00:18:47,090
and honestly, we just get
one chance to take this data.

417
00:18:47,690 --> 00:18:49,389
We couldn't stop them,
be like, "Oh, excuse me.

418
00:18:49,390 --> 00:18:51,120
Could you launch that rocket
one more time?

419
00:18:51,270 --> 00:18:52,360
I didn't get the right data."

420
00:18:52,720 --> 00:18:54,000
So a lot of engineering and work

421
00:18:54,720 --> 00:18:56,660
went into making sure
it was structurally sound,

422
00:18:56,720 --> 00:18:58,300
we were able to get
the frequency right

423
00:18:58,450 --> 00:19:00,540
and all the data correctly
during this experiment.

424
00:19:03,150 --> 00:19:05,060
Here I'll show you a video
of what it looked like.

425
00:19:05,420 --> 00:19:06,570
The sound image is on the left,

426
00:19:07,150 --> 00:19:09,270
and the camera that's really
close to it is on the right

427
00:19:09,570 --> 00:19:10,720
to better see what's going on.

428
00:19:11,780 --> 00:19:14,030
You can see a lot of noise
coming from the nozzle itself.

429
00:19:16,120 --> 00:19:17,839
There is actually a duct
that goes under the launch pad

430
00:19:17,840 --> 00:19:18,840
that comes out at the exit.

431
00:19:20,090 --> 00:19:22,029
And once it shows it again,
you can see a lot of noise

432
00:19:22,030 --> 00:19:23,720
actually coming
out of the exit duct as well.

433
00:19:26,510 --> 00:19:27,870
We have
a water suppressant system

434
00:19:28,750 --> 00:19:30,270
that actually
suppresses the noise.

435
00:19:31,330 --> 00:19:32,720
Have any of you seen
a launch before?

436
00:19:34,720 --> 00:19:35,720
Probably majority of you?

437
00:19:35,870 --> 00:19:37,510
Okay, so, if you ever
see the water system

438
00:19:38,810 --> 00:19:40,510
that's getting blown
onto the launch pad,

439
00:19:40,630 --> 00:19:42,450
I always thought
it was to cool the launch pad,

440
00:19:42,840 --> 00:19:44,360
but it's actually
to suppress noise.

441
00:19:45,390 --> 00:19:47,450
And because of this test,
it changed the whole system

442
00:19:48,750 --> 00:19:50,750
of how launches were done
in the future after this.

443
00:19:52,150 --> 00:19:53,450
It had to be initiated
a lot sooner

444
00:19:54,810 --> 00:19:57,150
to suppress the noise.

445
00:20:00,450 --> 00:20:01,450
On to more rockets.

446
00:20:02,630 --> 00:20:04,570
We have a huge group
in partnership with Stanford

447
00:20:07,210 --> 00:20:09,030
working on
liquefying hybrid rocket motors.

448
00:20:10,750 --> 00:20:12,030
We've done 41 tests here at Ames

449
00:20:12,660 --> 00:20:14,120
and over 500 ground tests
overall.

450
00:20:14,870 --> 00:20:16,450
A lot of effort
and work went into this.

451
00:20:17,420 --> 00:20:18,600
And here's some few advantages

452
00:20:19,660 --> 00:20:21,120
of this liquefying
hybrid rocket.

453
00:20:22,390 --> 00:20:23,780
First it uses
a paraffin solid fuel,

454
00:20:25,330 --> 00:20:26,330
than the normal HTPB fuel.

455
00:20:28,870 --> 00:20:30,060
It burns three times faster.

456
00:20:30,390 --> 00:20:31,390
What does that give us?

457
00:20:31,660 --> 00:20:33,480
Well, it gives us
a more simple system to burn.

458
00:20:35,000 --> 00:20:36,810
Here, that's what the fuel
normally looks like.

459
00:20:38,000 --> 00:20:40,120
You have multiple ports
for it to burn evenly through.

460
00:20:41,630 --> 00:20:43,150
Because it burns
three times faster,

461
00:20:43,480 --> 00:20:45,180
we don't need
the multiple ports anymore.

462
00:20:45,270 --> 00:20:47,300
We have one port where it
could burn evenly through.

463
00:20:48,420 --> 00:20:50,450
And with multiple ports,
if it doesn't burn evenly,

464
00:20:51,240 --> 00:20:52,600
it could cause
structural damage,

465
00:20:54,090 --> 00:20:55,600
and it makes rockets
a little less safe.

466
00:20:57,270 --> 00:20:58,480
But with this,
it's a lot safer,

467
00:20:58,570 --> 00:21:00,150
and it's environmentally
friendly.

468
00:21:01,150 --> 00:21:03,300
Right here, and on the right,
we have a Peregrine rocket

469
00:21:05,660 --> 00:21:07,840
that we hope to test roughly
one year from now at Wallops.

470
00:21:10,450 --> 00:21:12,510
In 2014, we conducted tests
that shows that this fuel

471
00:21:14,150 --> 00:21:15,690
is both viable
and stable and efficient,

472
00:21:17,330 --> 00:21:19,360
and it's able to fly in a flight
with configuration.

473
00:21:20,720 --> 00:21:22,780
I also want to emphasize
the advantage of this rocket

474
00:21:24,300 --> 00:21:25,300
where it has the advantage

475
00:21:26,270 --> 00:21:27,870
of both a solid-
and liquid-state rocket.

476
00:21:28,780 --> 00:21:30,690
With a solid state,
you get a really high thrust,

477
00:21:31,270 --> 00:21:32,270
but it's on and off.

478
00:21:32,690 --> 00:21:34,810
You light it up, it lights,
it burns, and then it's off.

479
00:21:36,450 --> 00:21:38,390
With the liquid fuel,
you're able to throttle it.

480
00:21:38,840 --> 00:21:40,480
This hybrid rocket,
it's able to do both.

481
00:21:41,270 --> 00:21:43,660
You have a liquid-state fuel,
and you have a solid-state fuel,

482
00:21:44,750 --> 00:21:45,810
and it's really efficient,

483
00:21:50,240 --> 00:21:52,240
so...

484
00:21:53,840 --> 00:21:54,840
Here you go.

485
00:21:55,090 --> 00:21:58,090
[rocket engine firing]

486
00:22:13,750 --> 00:22:14,750
Beautiful.

487
00:22:15,360 --> 00:22:16,360
Very complete.

488
00:22:16,540 --> 00:22:17,540
This was a ground test.

489
00:22:17,720 --> 00:22:18,870
It was parallel to the ground,

490
00:22:20,570 --> 00:22:22,030
but it's usually
pointed upwards,

491
00:22:22,510 --> 00:22:23,510
so we could go up.

492
00:22:24,570 --> 00:22:25,570
[laughter]

493
00:22:27,480 --> 00:22:29,210
So we talked a lot
about going up into space.

494
00:22:30,630 --> 00:22:32,120
What about coming back down
to space

495
00:22:32,150 --> 00:22:33,360
or even other planetary bodies?

496
00:22:34,690 --> 00:22:36,180
Coming back down,
it's really fast,

497
00:22:36,600 --> 00:22:38,779
and it's really harsh, and it's
a really hot environment.

498
00:22:38,780 --> 00:22:40,390
So we use something
called a heat shield

499
00:22:40,600 --> 00:22:41,600
to protect our vehicle,

500
00:22:41,750 --> 00:22:43,480
our instrumentation,
and our astronauts.

501
00:22:44,660 --> 00:22:47,000
And to simulate that, we have
a facility called the Arc Jet

502
00:22:48,000 --> 00:22:49,630
to test these
thermal protection systems.

503
00:22:50,750 --> 00:22:52,120
Right now you have
a heat shield,

504
00:22:53,270 --> 00:22:55,060
and it's being put
into the arc jet right now.

505
00:22:57,090 --> 00:22:58,360
So typically,
for us to quantify

506
00:22:59,300 --> 00:23:01,810
how well it worked, we measure
the heat shield material before,

507
00:23:03,300 --> 00:23:05,329
and once that's done, we measure
the heat shield after,

508
00:23:05,330 --> 00:23:07,030
and that's
how much material has ablated.

509
00:23:07,330 --> 00:23:09,270
The material has to ablate
to dissipate the heat.

510
00:23:12,540 --> 00:23:14,600
In the Fluid Mechanics Lab,
we developed a better way

511
00:23:14,810 --> 00:23:16,450
to do this to actually see
what's going on

512
00:23:17,270 --> 00:23:18,630
between the beginning
and the end.

513
00:23:21,690 --> 00:23:23,840
We call this photogrammetric
recession measurement.

514
00:23:24,720 --> 00:23:26,120
It uses the same technique
as PIV,

515
00:23:27,270 --> 00:23:28,660
but instead of
tracking molecules,

516
00:23:29,210 --> 00:23:31,390
you're actually tracking
the surface of the heat shield

517
00:23:31,690 --> 00:23:32,690
being ablated away.

518
00:23:33,360 --> 00:23:34,750
Right now we have PICA
in the arc jet.

519
00:23:38,090 --> 00:23:40,420
And one great use of this is,
what if the ablation was uneven?

520
00:23:42,420 --> 00:23:44,690
Like, how would you know that
measuring it before and after

521
00:23:44,690 --> 00:23:46,359
and when it actually
started becoming uneven?

522
00:23:46,360 --> 00:23:48,510
With this technique, you're able
to see it in real time.

523
00:23:50,570 --> 00:23:53,120
And it's actually extremely hard
to put any sort of instruments

524
00:23:53,450 --> 00:23:55,300
that would survive
in this kind of conditions,

525
00:23:56,060 --> 00:23:57,750
and a lot of engineering
also went into this.

526
00:23:59,810 --> 00:24:03,810
The surface right here
is brighter than the sun, so...

527
00:24:08,660 --> 00:24:10,180
Like I mentioned
from the beginning,

528
00:24:10,840 --> 00:24:11,840
coming back into space,

529
00:24:12,360 --> 00:24:14,600
NASA Ames is also home to
the world's largest wind tunnel.

530
00:24:16,750 --> 00:24:18,030
It could fit a full-scale F-18,

531
00:24:20,090 --> 00:24:21,270
even a full-scale semi-truck.

532
00:24:22,360 --> 00:24:24,420
But what better way to use it
than to test parachutes?

533
00:24:25,570 --> 00:24:27,420
On the left--this was done
earlier this year--

534
00:24:28,060 --> 00:24:29,450
it's two
out of the three parachutes

535
00:24:29,780 --> 00:24:31,060
that would be deployed on Orion

536
00:24:31,570 --> 00:24:32,720
when it comes back onto Earth.

537
00:24:34,720 --> 00:24:37,090
On the very right, you have
the Mars Science Lab parachute.

538
00:24:38,150 --> 00:24:39,660
It's the largest
supersonic parachute

539
00:24:40,060 --> 00:24:41,780
ever successfully designed
right over here.

540
00:24:44,180 --> 00:24:46,510
And what's incredible about
this parachute in particular,

541
00:24:47,000 --> 00:24:48,180
it's moving--it's taking MSL,

542
00:24:49,150 --> 00:24:50,750
or "Curiosity,"
onto the Mars atmosphere

543
00:24:51,330 --> 00:24:53,060
but when it's approaching
the atmosphere,

544
00:24:54,060 --> 00:24:55,810
it's going about...
over 1,000 miles per hour,

545
00:24:57,000 --> 00:24:58,060
and it's the size of a Prius.

546
00:24:58,480 --> 00:25:00,870
And we have to slow this Prius
down to about 200 miles per hour

547
00:25:01,600 --> 00:25:02,600
with just one parachute.

548
00:25:04,000 --> 00:25:05,000
Pretty incredible.

549
00:25:05,570 --> 00:25:08,030
I recommend YouTubing "Seven
Minutes of Terror"on YouTube.

550
00:25:08,480 --> 00:25:10,510
It also shows you the other
complicated techniques

551
00:25:10,720 --> 00:25:11,720
with zero margin of error

552
00:25:12,720 --> 00:25:15,570
how to make this mission
successful.

553
00:25:18,420 --> 00:25:19,600
Here we had a high-speed camera

554
00:25:20,150 --> 00:25:21,540
capture
the successful deployment

555
00:25:22,150 --> 00:25:23,510
of the Mars Science Lab
parachute.

556
00:25:24,330 --> 00:25:25,420
Of course, it's slowed down.

557
00:25:25,720 --> 00:25:27,300
We had some problems
in the beginning,

558
00:25:28,300 --> 00:25:30,300
but at the end, we were able
to solve those problems

559
00:25:30,330 --> 00:25:31,690
and have
a successful deployment.

560
00:25:32,330 --> 00:25:34,840
But did this work?

561
00:25:36,630 --> 00:25:37,630
Here's proof.

562
00:25:37,750 --> 00:25:38,750
I took it with my iPhone.

563
00:25:39,150 --> 00:25:40,150
[laughter]

564
00:25:41,090 --> 00:25:43,210
So this is "Curiosity"landing
on Mars August 5, 2012,

565
00:25:45,480 --> 00:25:48,030
and everything went flawlessly,
and the mission was a success.

566
00:25:50,390 --> 00:25:52,240
Okay, so I talked a lot
about supersonic speeds

567
00:25:53,630 --> 00:25:54,840
and breaking the sound barrier,

568
00:25:55,270 --> 00:25:57,210
but how does it look like
to the naked eye on Earth?

569
00:25:59,180 --> 00:26:00,240
Well, I got a photo.

570
00:26:00,660 --> 00:26:02,060
This is an F-18
flying about Mach 1

571
00:26:03,540 --> 00:26:04,600
over the San Francisco Bay.

572
00:26:04,870 --> 00:26:06,150
It's about 40 feet above water.

573
00:26:07,150 --> 00:26:08,150
It's a very daring pilot,

574
00:26:08,750 --> 00:26:10,480
and you can see the shocks
coming off of here

575
00:26:10,570 --> 00:26:11,570
or even the canopy.

576
00:26:12,630 --> 00:26:14,360
When shocks occur,
it's usually a change--

577
00:26:14,810 --> 00:26:16,390
it's a change
of pressure and density.

578
00:26:16,690 --> 00:26:18,150
So that's what
you're seeing here.

579
00:26:18,330 --> 00:26:21,450
I'll call it
a real-life Schlieren photo.

580
00:26:23,540 --> 00:26:24,600
But what does it sound like?

581
00:26:25,660 --> 00:26:26,660
Well...

582
00:26:26,660 --> 00:26:29,660
[loud boom]

583
00:26:32,870 --> 00:26:33,870
[roaring]

584
00:26:35,360 --> 00:26:36,360
[crowd exclaiming]

585
00:26:36,840 --> 00:26:37,840
[roaring]

586
00:26:39,600 --> 00:26:41,600
(woman)
Whoo-hoo-hoo-hoo-hoo!

587
00:26:43,870 --> 00:26:44,870
[loud boom]

588
00:26:47,720 --> 00:26:49,630
(man)
Sound travels
at about 760 miles per hour

589
00:26:51,660 --> 00:26:52,660
or 340 meters per second.

590
00:26:54,270 --> 00:26:56,330
That's about 661 knots
on an average day at sea level.

591
00:26:58,510 --> 00:27:00,060
And sometimes
you can almost see it.

592
00:27:01,840 --> 00:27:03,119
(Christina)
That's how it sounds like.

593
00:27:03,120 --> 00:27:04,120
[laughs]

594
00:27:04,540 --> 00:27:06,780
Keep in mind you're also hearing
a lot of the engine noises

595
00:27:07,150 --> 00:27:08,150
that are coming off of it,

596
00:27:08,660 --> 00:27:10,149
but I definitely don't want
one of these planes

597
00:27:10,150 --> 00:27:11,420
flying over my house
at 3:00 a.m.

598
00:27:14,480 --> 00:27:16,210
So NASA actually
has a supersonics program

599
00:27:17,570 --> 00:27:19,359
in partnership with a lot
of commercial companies

600
00:27:19,360 --> 00:27:21,180
such as Lockheed or Boeing
and other entities

601
00:27:22,000 --> 00:27:24,030
where we're trying
to reduce the sound signature--

602
00:27:24,390 --> 00:27:26,510
boom signature so it could fly
over land efficiently.

603
00:27:28,750 --> 00:27:30,810
These are several of the designs
that they have here.

604
00:27:31,270 --> 00:27:32,630
And this is
for commercial planes.

605
00:27:33,090 --> 00:27:35,150
So one of you, you and I
could fly in one of these planes

606
00:27:35,450 --> 00:27:36,450
in the next 15, 20 years.

607
00:27:36,720 --> 00:27:37,720
How amazing would that be?

608
00:27:38,660 --> 00:27:40,270
And so instead of going
to New York, say,

609
00:27:40,660 --> 00:27:42,480
in, like, 5 hours,
you're there in 2 1/2 hours.

610
00:27:43,210 --> 00:27:44,689
I'll definitely go to New York
a lot more often

611
00:27:44,690 --> 00:27:45,690
if I had the money.

612
00:27:46,450 --> 00:27:47,450
Right here.

613
00:27:49,240 --> 00:27:51,060
And to point out,
back here is a pressure rail,

614
00:27:53,330 --> 00:27:55,780
and that's what we're using to
measure the sonic boom signature

615
00:27:56,300 --> 00:27:57,300
coming off of the plane.

616
00:27:58,000 --> 00:27:59,480
And the pointy nose
and the wing itself

617
00:28:01,240 --> 00:28:02,750
all reduces the noise
of that boom, boom

618
00:28:04,150 --> 00:28:05,780
that you hear
when it's flying over as well.

619
00:28:08,300 --> 00:28:09,300
Okay.

620
00:28:09,510 --> 00:28:10,690
So what about subsonic planes?

621
00:28:11,810 --> 00:28:14,150
What have we done for those
instead of supersonic planes?

622
00:28:15,150 --> 00:28:16,239
Well, we've actually done
a lot of work

623
00:28:16,240 --> 00:28:17,420
to make planes more efficient,

624
00:28:17,660 --> 00:28:20,090
part of the environmentally
responsible aviation program

625
00:28:20,720 --> 00:28:21,720
here at Ames.

626
00:28:23,270 --> 00:28:24,269
One technique
that we've developed

627
00:28:24,270 --> 00:28:25,330
is called the sweeping jet.

628
00:28:26,090 --> 00:28:28,150
Right now what you're seeing
is the 40x80 wind tunnel

629
00:28:28,840 --> 00:28:30,660
with a full-sized
Boeing 757 tail installed.

630
00:28:33,090 --> 00:28:34,810
So these sweeping jets
right here that you see

631
00:28:36,330 --> 00:28:37,840
has no moving parts,
and about 30 of them

632
00:28:38,510 --> 00:28:41,060
are installed on these hinges,
which provides us flow control.

633
00:28:42,840 --> 00:28:45,330
Because these are installed,
it provides 20% more side force,

634
00:28:47,720 --> 00:28:48,720
which results in--

635
00:28:50,240 --> 00:28:51,630
we don't need tails
that big anymore

636
00:28:52,600 --> 00:28:53,600
for the plane to fly.

637
00:28:54,060 --> 00:28:55,660
So we could reduce the size
tremendously,

638
00:28:57,090 --> 00:28:58,450
therefore reducing
mass and drag,

639
00:29:00,300 --> 00:29:01,720
and giving us
a more efficient plane.

640
00:29:03,330 --> 00:29:04,390
This was a successful test,

641
00:29:04,870 --> 00:29:06,870
and they actually tested it
in flight in April 2015

642
00:29:08,480 --> 00:29:09,840
on an ecoDemonstrator
right here,

643
00:29:11,240 --> 00:29:12,750
and that was also
a successful mission.

644
00:29:14,060 --> 00:29:15,600
I suspect to be
seeing these flow control

645
00:29:17,870 --> 00:29:20,120
on all future planes.

646
00:29:22,870 --> 00:29:25,030
Here's one test that's going on
right now as we speak.

647
00:29:26,330 --> 00:29:28,360
I was actually walking
next to the plane yesterday,

648
00:29:28,690 --> 00:29:30,420
putting it
into the wind tunnel right here.

649
00:29:31,090 --> 00:29:32,300
It's the hybrid wing body plane.

650
00:29:33,120 --> 00:29:35,150
It's a plane that's
both designed by NASA and Boeing

651
00:29:36,630 --> 00:29:37,630
right here.

652
00:29:37,630 --> 00:29:39,000
So environmentally responsible

653
00:29:39,120 --> 00:29:40,510
doesn't just mean
fuel efficiency.

654
00:29:41,540 --> 00:29:42,840
It also means
reducing the noise.

655
00:29:44,030 --> 00:29:45,120
So we have the engines on top.

656
00:29:46,120 --> 00:29:47,390
They're typically on the bottom,

657
00:29:47,480 --> 00:29:49,390
and this kind of shields
the noise off the ground

658
00:29:50,720 --> 00:29:51,720
right over here.

659
00:29:52,600 --> 00:29:54,540
And this nice blended wing body
gives us actually

660
00:29:56,240 --> 00:29:58,090
a lot more efficiency
and higher cruise speed.

661
00:29:59,750 --> 00:30:00,750
You can see over here.

662
00:30:01,330 --> 00:30:02,840
And back
to the air aeroacoustics team,

663
00:30:03,420 --> 00:30:05,540
we also installed several
acoustics array right here

664
00:30:06,210 --> 00:30:07,210
to measure the sound.

665
00:30:09,390 --> 00:30:10,390
Pretty great.

666
00:30:13,330 --> 00:30:14,420
This here is a special plane.

667
00:30:15,570 --> 00:30:17,060
It's a design
that's commonly used.

668
00:30:18,750 --> 00:30:19,750
It's nonproprietary,

669
00:30:21,030 --> 00:30:22,300
and it's used
all over the world.

670
00:30:23,060 --> 00:30:25,210
So this plane, you could use
your computational method

671
00:30:26,210 --> 00:30:28,480
or your experimental method
that you developed in your lab

672
00:30:28,630 --> 00:30:30,090
or install
different wind tunnels

673
00:30:30,120 --> 00:30:31,120
and go back to the database

674
00:30:31,570 --> 00:30:33,360
that everyone can use
and validate your data

675
00:30:33,690 --> 00:30:35,270
or check if it's right
or even close by.

676
00:30:35,780 --> 00:30:36,780
It's really useful,

677
00:30:37,000 --> 00:30:38,119
especially if you're not
part of NASA,

678
00:30:38,120 --> 00:30:40,120
you really want to check
your computational code.

679
00:30:40,150 --> 00:30:41,150
How do you do that?

680
00:30:41,270 --> 00:30:42,810
Well, you run it
on the same model, right?

681
00:30:43,540 --> 00:30:44,540
Angle check there.

682
00:30:45,540 --> 00:30:46,749
We've even done
some work ourselves

683
00:30:46,750 --> 00:30:48,720
in the Fluid Mechanics Lab.

684
00:30:51,090 --> 00:30:52,090
Right over here.

685
00:30:52,180 --> 00:30:53,390
So this is
a semi-span CRM model

686
00:30:55,240 --> 00:30:56,600
tested in
our low-speed test cell.

687
00:30:58,060 --> 00:31:00,360
And these blue streaks are
actually oil that was applied.

688
00:31:01,630 --> 00:31:02,689
We turned on the wind tunnel,

689
00:31:02,690 --> 00:31:04,180
and we were able to see
the flow field

690
00:31:04,480 --> 00:31:05,540
on the surface of the model,

691
00:31:06,390 --> 00:31:08,390
give us this nice visual effect
of what's going on.

692
00:31:09,690 --> 00:31:10,690
On the left and on the right

693
00:31:11,540 --> 00:31:13,060
we're measuring
wing-tip vortices.

694
00:31:13,450 --> 00:31:15,510
On the left, we use a covert
probe or a four-hole probe

695
00:31:16,660 --> 00:31:18,240
that measures pressure
along a plane.

696
00:31:20,510 --> 00:31:21,749
And on the right,
in the same plane,

697
00:31:21,750 --> 00:31:23,570
we used PIV to
measure velocities right here.

698
00:31:27,330 --> 00:31:28,330
So why is it important

699
00:31:28,450 --> 00:31:30,180
that we understand
the wing-tip vortices?

700
00:31:30,240 --> 00:31:32,090
Well, have you ever
sat on a plane and wondered,

701
00:31:33,780 --> 00:31:35,329
"The other plane's
already taken off.

702
00:31:35,330 --> 00:31:37,390
Why am I still sitting here?
Why haven't we taken off?

703
00:31:37,600 --> 00:31:39,240
I can't wait to go home
for Thanksgiving.

704
00:31:39,330 --> 00:31:40,600
My food's getting cold,"
right?

705
00:31:42,000 --> 00:31:44,030
Well, actually, wing-tip
vortices can be so strong

706
00:31:45,060 --> 00:31:47,210
that, if we're flying way
too closely on the next plane,

707
00:31:48,810 --> 00:31:50,540
it could flip another plane
over behind it.

708
00:31:52,780 --> 00:31:54,240
Which leads me
to our next project.

709
00:31:55,060 --> 00:31:57,300
Here we study wing-tip vortices
and how to alleviate them

710
00:31:58,420 --> 00:32:00,330
using vortices
coming off the tail right here.

711
00:32:02,330 --> 00:32:04,030
So if one vortice's
coming off the wing tip

712
00:32:04,480 --> 00:32:05,480
going one direction,

713
00:32:06,000 --> 00:32:08,059
what if we had another vortice
going in a different direction,

714
00:32:08,060 --> 00:32:09,060
coming off the tail,

715
00:32:09,300 --> 00:32:11,000
and basically cancelling
each other out?

716
00:32:12,450 --> 00:32:14,180
This did work,
but the plane configuration

717
00:32:15,480 --> 00:32:17,390
is just not a viable
plane configuration to fly.

718
00:32:18,090 --> 00:32:19,270
But we did prove that it worked.

719
00:32:20,000 --> 00:32:21,840
On the bottom right,
the red shows one direction.

720
00:32:23,330 --> 00:32:25,389
The blue shows a different
direction of the vortices.

721
00:32:25,390 --> 00:32:27,120
These are two vortices
coming from the wing

722
00:32:27,630 --> 00:32:29,210
and two vortices
coming from the tail.

723
00:32:30,030 --> 00:32:32,600
Let me show you how it worked.

724
00:32:40,120 --> 00:32:41,630
If we could find a way
to get this to work,

725
00:32:42,630 --> 00:32:47,270
we could reduce airline traffic
by an incredible amount.

726
00:32:51,180 --> 00:32:52,570
So we talked a lot
about spacecrafts

727
00:32:52,840 --> 00:32:54,150
and aircrafts and air vehicles.

728
00:32:54,540 --> 00:32:55,540
We don't just do just that.

729
00:32:56,390 --> 00:32:58,390
In the last 15 years,
we've also studied truck drag

730
00:32:59,270 --> 00:33:01,120
and wondering:
why is truck drag important?

731
00:33:01,810 --> 00:33:03,270
Well, trucks consume 13%
of the oil

732
00:33:04,750 --> 00:33:05,810
we use in the United States,

733
00:33:06,660 --> 00:33:08,060
and over 60% of that fuel
on a truck

734
00:33:08,630 --> 00:33:10,000
is to overcome aerodynamic drag.

735
00:33:10,810 --> 00:33:13,180
That's a huge amount of fuel
overcoming aerodynamic drag.

736
00:33:14,240 --> 00:33:16,240
So if we could even make it
to 5%, 10%, 15% less drag,

737
00:33:18,330 --> 00:33:20,450
imagine how much fuel savings
we could have in the U.S.

738
00:33:21,690 --> 00:33:23,270
So here we have
a side and base extender

739
00:33:25,120 --> 00:33:26,120
to cover up the gap.

740
00:33:26,540 --> 00:33:27,540
That also reduces drag.

741
00:33:28,150 --> 00:33:29,750
Another thing
we tried is lowboy trailer,

742
00:33:30,600 --> 00:33:31,600
or we called it side flaps.

743
00:33:32,720 --> 00:33:34,420
Here it could reduce the drag
by about 10%.

744
00:33:35,510 --> 00:33:37,300
And if you want to add
the trailer base flaps,

745
00:33:38,330 --> 00:33:40,060
it could reduce drag
by 15% right over here.

746
00:33:41,570 --> 00:33:43,720
You could see a lot of this
being implemented out there.

747
00:33:44,210 --> 00:33:45,210
If you drive on Highway 5

748
00:33:46,000 --> 00:33:47,510
or even on 101,
a lot of trucks have this.

749
00:33:49,360 --> 00:33:51,420
Most of them already have
the side and base extenders

750
00:33:51,840 --> 00:33:54,240
covering the gap for you.

751
00:33:59,300 --> 00:34:00,360
On to the fun part.

752
00:34:02,000 --> 00:34:03,000
So NASA's mission

753
00:34:03,240 --> 00:34:05,150
is to inspire the next
generation of explorers.

754
00:34:05,840 --> 00:34:07,030
So the next couple of slides,

755
00:34:07,180 --> 00:34:08,659
I'm gonna show you
student-based projects

756
00:34:08,660 --> 00:34:10,390
that we've done
in the Fluid Mechanics Lab.

757
00:34:13,570 --> 00:34:15,030
Here we have
a fruit fly experiment

758
00:34:15,780 --> 00:34:17,180
that was done
over three summers,

759
00:34:17,390 --> 00:34:19,300
and it was pretty much solely
an intern project.

760
00:34:20,750 --> 00:34:22,030
It was used to track and analyze

761
00:34:22,420 --> 00:34:24,480
how fruit flies flew
in micro-gravity environment.

762
00:34:25,120 --> 00:34:27,480
But the biggest challenge was
fitting this whole experiment

763
00:34:27,540 --> 00:34:28,540
in a 4-inch by 6-inch box.

764
00:34:30,300 --> 00:34:31,300
You can see here.

765
00:34:32,390 --> 00:34:33,390
Pretty great.

766
00:34:34,390 --> 00:34:36,210
This experiment flew up
to the ISS last summer

767
00:34:36,450 --> 00:34:38,720
on a SpaceX rocket.

768
00:34:43,060 --> 00:34:45,060
Here we've done a lot
of sports ball aerodynamics,

769
00:34:46,030 --> 00:34:47,540
student-based
educational programs.

770
00:34:48,570 --> 00:34:50,810
On the top left, you see a
tennis ball that's not spinning,

771
00:34:52,090 --> 00:34:53,630
and we're injecting smoke
into the flow.

772
00:34:54,300 --> 00:34:55,720
You see
a very symmetric flow pattern

773
00:34:56,810 --> 00:34:58,270
on top and on the bottom
of the ball.

774
00:35:00,720 --> 00:35:02,090
And here we have
a spinning ball.

775
00:35:03,390 --> 00:35:04,390
It's spinning this way.

776
00:35:04,540 --> 00:35:06,150
So you have the weight
going further out

777
00:35:06,330 --> 00:35:07,840
and the separation
going further down,

778
00:35:08,570 --> 00:35:09,780
so this causes a downward force.

779
00:35:11,600 --> 00:35:12,600
Oh.

780
00:35:12,600 --> 00:35:13,660
It's probably easier to see

781
00:35:13,660 --> 00:35:15,150
if I show you a video
of it happening.

782
00:35:16,030 --> 00:35:17,030
Here it's a baseball.

783
00:35:17,090 --> 00:35:18,090
Again, symmetric flow

784
00:35:18,240 --> 00:35:20,030
both on the top
and on the bottom of this ball.

785
00:35:21,150 --> 00:35:23,510
And once it starts spinning, you
can see how the flow changes.

786
00:35:24,420 --> 00:35:26,270
The wake starts coming
right off further down,

787
00:35:27,750 --> 00:35:29,570
and you have the separation
going further up,

788
00:35:30,210 --> 00:35:31,210
causing a sideways force.

789
00:35:31,870 --> 00:35:33,120
That's how a curveball works,

790
00:35:34,690 --> 00:35:35,690
upward force.

791
00:35:38,300 --> 00:35:39,300
So, fun fact, a tennis ball

792
00:35:40,300 --> 00:35:42,210
has the highest drag
out of all the sports balls.

793
00:35:44,060 --> 00:35:45,060
Why is that?

794
00:35:45,360 --> 00:35:47,000
It's 'cause it has
the roughest surface.

795
00:35:48,000 --> 00:35:49,000
So we tested that as well.

796
00:35:50,060 --> 00:35:52,240
We have the same tennis ball
tested at different speeds.

797
00:35:53,510 --> 00:35:54,510
First is at low speed.

798
00:35:54,720 --> 00:35:56,389
You can see the filaments
kind of sticking out

799
00:35:56,390 --> 00:35:57,780
kind of like hair on your arm,
right?

800
00:35:59,210 --> 00:36:00,630
A really rough surface,
high drag.

801
00:36:01,600 --> 00:36:03,300
We tested that same ball
at higher speeds,

802
00:36:03,750 --> 00:36:05,360
but now all the filaments
are laid down.

803
00:36:07,570 --> 00:36:10,180
Smoother ball, less drag.

804
00:36:14,630 --> 00:36:16,210
How many of you have seen
the World Cup?

805
00:36:18,600 --> 00:36:19,600
A lot of you.

806
00:36:20,330 --> 00:36:21,480
So the last couple World Cups,

807
00:36:21,600 --> 00:36:23,750
there have been a lot of
controversy on the soccer ball.

808
00:36:24,270 --> 00:36:26,300
Every World Cup, they have
a new soccer ball design.

809
00:36:26,750 --> 00:36:28,120
It's not just
for the looks of it.

810
00:36:28,690 --> 00:36:30,630
The aerodynamics
are actually quite different,

811
00:36:30,750 --> 00:36:32,660
and that's because
of the roughness of the ball.

812
00:36:33,450 --> 00:36:35,600
The roughness is determined
by the length of the seams,

813
00:36:37,030 --> 00:36:38,030
how deep the seams are,

814
00:36:38,420 --> 00:36:40,120
and the pimples
on the surface of the ball.

815
00:36:42,750 --> 00:36:44,360
This last year,
it was the Brazuca ball.

816
00:36:45,090 --> 00:36:47,000
It was a lot rougher
than the previous World Cup,

817
00:36:49,240 --> 00:36:51,030
and therefore,
changing the aerodynamics.

818
00:36:51,510 --> 00:36:53,449
The goalies and the players
are actually a lot happier

819
00:36:53,450 --> 00:36:55,600
with this ball, and we had
no complaints this last year.

820
00:36:58,450 --> 00:37:00,750
I would recommend Googling
or YouTubing Brazuca or NASA.

821
00:37:03,510 --> 00:37:04,869
There's a lot
of great articles about it,

822
00:37:04,870 --> 00:37:06,480
a lot of great videos
to show you the work

823
00:37:06,660 --> 00:37:07,810
that we put into our research,

824
00:37:08,450 --> 00:37:09,720
and a lot
of the student projects

825
00:37:09,720 --> 00:37:12,060
to get students excited
about aerodynamics with sports.

826
00:37:14,180 --> 00:37:15,180
So it's really great.

827
00:37:18,060 --> 00:37:20,120
And lastly, how many of you
have seen "MythBusters?"

828
00:37:21,750 --> 00:37:22,750
A lot of you.

829
00:37:23,060 --> 00:37:24,750
We have a few stars
in the audience right now.

830
00:37:26,540 --> 00:37:28,390
So anytime "Mythbusters"has
an aero problem,

831
00:37:29,480 --> 00:37:30,480
who do they come to?

832
00:37:30,570 --> 00:37:32,090
They come
to the Fluid Mechanics Lab.

833
00:37:32,540 --> 00:37:33,749
They've been here several times.

834
00:37:33,750 --> 00:37:35,450
When I was an intern,
they were here twice.

835
00:37:35,780 --> 00:37:36,780
It was pretty cool.

836
00:37:38,390 --> 00:37:39,540
And they test all their myths.

837
00:37:40,060 --> 00:37:41,780
One of my favorite myths
is the golf ball myth.

838
00:37:42,720 --> 00:37:44,420
So say you have a golf ball
and it's dimpled

839
00:37:46,060 --> 00:37:48,210
and have the same exact ball
that's completely smooth.

840
00:37:48,510 --> 00:37:50,029
If I hit it
with the same amount of force,

841
00:37:50,030 --> 00:37:51,210
the golf ball goes twice as far,

842
00:37:52,090 --> 00:37:54,540
and that's because of the dimple
on the golf ball reducing drag.

843
00:37:55,570 --> 00:37:57,210
So will that same idea
work on, say, a car?

844
00:37:59,600 --> 00:38:01,690
If I dimpled my car,
would I get twice the efficiency

845
00:38:02,870 --> 00:38:03,870
on my gas usage?

846
00:38:05,570 --> 00:38:07,270
Well, we had actually
high school interns

847
00:38:08,030 --> 00:38:09,030
test that out here as well,

848
00:38:11,150 --> 00:38:12,150
and as a matter of fact,

849
00:38:13,600 --> 00:38:15,000
you actually
don't get less drag.

850
00:38:16,150 --> 00:38:17,150
It actually makes it worse

851
00:38:18,000 --> 00:38:20,120
from our experiment that
we've done with the interns.

852
00:38:20,480 --> 00:38:22,000
And right here,
when they first came,

853
00:38:23,630 --> 00:38:25,450
I think this was
actually when I was an intern.

854
00:38:25,750 --> 00:38:27,120
They got to visit.
I couldn't go.

855
00:38:27,750 --> 00:38:30,120
They got to visit "Mythbusters"
<font color = #FFFFFF>up in San Francisco, so...</font>

856
00:38:32,180 --> 00:38:33,180
pretty cool.

857
00:38:34,450 --> 00:38:35,450
All right, questions?

858
00:38:37,480 --> 00:38:38,480
[applause]

859
00:38:38,870 --> 00:38:39,870
Thank you.

860
00:38:41,240 --> 00:38:44,090
[Christina laughs]

861
00:38:52,180 --> 00:38:54,570
No questions?
Okay.

862
00:39:00,720 --> 00:39:02,120
Well, that makes it
easier for me.

863
00:39:02,480 --> 00:39:04,330
We'll have the center microphone
in the aisle,

864
00:39:04,750 --> 00:39:06,870
so please filter around
and ask your questions there.

865
00:39:09,420 --> 00:39:10,420
I don't bite.
I promise.

866
00:39:12,090 --> 00:39:13,090
Maybe a little.

867
00:39:14,360 --> 00:39:15,360
You have a question here?

868
00:39:17,840 --> 00:39:18,840
(woman)
Yeah, the PIV,

869
00:39:19,750 --> 00:39:21,060
what is the code
that you use...

870
00:39:21,870 --> 00:39:23,030
[continues indistinctly]

871
00:39:24,270 --> 00:39:26,060
(man)
Could you go to the mic
and ask please?

872
00:39:28,030 --> 00:39:29,180
(woman)
Yeah, my question is

873
00:39:30,210 --> 00:39:31,810
about the particle imaging
velocimetry,

874
00:39:32,450 --> 00:39:34,570
if you just happened to know
what code you use for that.

875
00:39:36,630 --> 00:39:38,360
And beautiful, excellent talk.
Thank you.

876
00:39:39,780 --> 00:39:41,840
(Christina)
Thank you.
Is JT in the audience today?

877
00:39:44,090 --> 00:39:45,090
Laura Kushner?

878
00:39:45,540 --> 00:39:47,870
(woman)
We tend to use LaVision,
just a commercial package

879
00:39:47,870 --> 00:39:48,870
that is available.

880
00:39:51,240 --> 00:39:52,240
We also use...

881
00:39:52,600 --> 00:39:53,660
[continues indistinctly]

882
00:39:56,810 --> 00:39:58,540
(man)
If you don't mind
repeating please?

883
00:39:59,060 --> 00:40:00,120
(woman)
Sure, no worries.

884
00:40:00,360 --> 00:40:02,390
We tend to use LaVision,
which is a software package

885
00:40:03,060 --> 00:40:04,330
that is commercially available.

886
00:40:06,090 --> 00:40:07,450
Sometimes we do use
in-house codes

887
00:40:08,150 --> 00:40:10,420
that we've written in-house
if there's something special

888
00:40:10,750 --> 00:40:12,060
that we want to do
with the data.

889
00:40:13,420 --> 00:40:14,780
(woman)
Oh, and one last question.

890
00:40:15,450 --> 00:40:16,510
Don't work in aeronautics.

891
00:40:17,360 --> 00:40:18,840
I like the SC picture
of the fruit flies

892
00:40:19,750 --> 00:40:21,330
because that's the branch
that I'm in,

893
00:40:21,600 --> 00:40:22,600
the space biology branch.

894
00:40:24,300 --> 00:40:25,839
But I've just been told
that the new winglets

895
00:40:25,840 --> 00:40:27,630
you see on aircraft
are a recent innovation,

896
00:40:29,750 --> 00:40:32,330
and I wondered if anyone could
address the aerodynamics aspects

897
00:40:33,240 --> 00:40:34,720
of these little winglet
innovations.

898
00:40:35,480 --> 00:40:37,000
The winglets,
the one that goes on...

899
00:40:37,870 --> 00:40:40,389
(Christina)
The little tips at the end
of the wings that now go up

900
00:40:40,390 --> 00:40:42,420
that, I think, are
a relatively recent innovation.

901
00:40:44,210 --> 00:40:45,810
- Okay, Don?
- I'll talk to that if you want.

902
00:40:46,840 --> 00:40:48,150
- Go ahead.
- So I'm Don Durston.

903
00:40:48,510 --> 00:40:50,000
I'm in the same branch
as Christina.

904
00:40:50,000 --> 00:40:51,000
I'm lucky to work with her.

905
00:40:51,870 --> 00:40:53,270
She's a rising star
in our branch.

906
00:40:53,660 --> 00:40:55,360
Winglets have been around
for a long time,

907
00:40:55,660 --> 00:40:56,870
several decades--what's that?

908
00:40:58,690 --> 00:40:59,750
[man speaks indistinctly]

909
00:41:00,180 --> 00:41:01,450
(Don)
Okay, stand up here, okay.

910
00:41:04,600 --> 00:41:05,839
So just in case
they're recording this,

911
00:41:05,840 --> 00:41:06,840
I'm Don Durston.

912
00:41:07,090 --> 00:41:08,449
I work in the same branch
as Christina.

913
00:41:08,450 --> 00:41:09,600
I'm an aerodynamicist there.

914
00:41:10,330 --> 00:41:12,030
Winglets have been around
for a long time,

915
00:41:12,210 --> 00:41:13,630
probably a couple
of decades or more.

916
00:41:15,600 --> 00:41:17,269
They've been tested
on various aircraft,

917
00:41:17,270 --> 00:41:18,660
but there's been
a lot more emphasis

918
00:41:19,420 --> 00:41:21,120
on trying to optimize them
in their shapes

919
00:41:22,120 --> 00:41:23,840
so that they really
do improve the efficiency

920
00:41:25,090 --> 00:41:26,780
of any kind of aircraft
that they put them on.

921
00:41:27,660 --> 00:41:29,690
You're seeing a lot
of airliners now with winglets.

922
00:41:30,540 --> 00:41:32,690
Southwest Airlines has put
winglets on all their 737s,

923
00:41:34,270 --> 00:41:36,300
and I'm seeing them
more and more on other aircraft.

924
00:41:36,840 --> 00:41:38,000
Basically what they do is--

925
00:41:39,600 --> 00:41:40,780
their basic mechanism
is that

926
00:41:41,000 --> 00:41:42,840
they give an effective
span increase to the wing.

927
00:41:45,030 --> 00:41:46,659
Anytime you can increase
the span a little bit,

928
00:41:46,660 --> 00:41:48,180
you're increasing
the aspect ratio.

929
00:41:48,720 --> 00:41:50,120
That's lower drag configuration.

930
00:41:52,600 --> 00:41:54,750
The winglets also do help
to distribute the wake vortex

931
00:41:57,030 --> 00:41:58,840
or the wing-tip vortices
that come off the tips,

932
00:41:59,750 --> 00:42:02,030
and they do help to make those
just a little bit weaker,

933
00:42:02,390 --> 00:42:04,750
and thus, you're reducing the
induced drag just a little bit.

934
00:42:05,540 --> 00:42:07,570
So it's kind of a complicated
aerodynamic problem.

935
00:42:10,450 --> 00:42:12,630
But with careful shaping
and integration into the wings

936
00:42:13,390 --> 00:42:15,720
of current aircraft, they
are finding substantial savings

937
00:42:17,510 --> 00:42:18,690
in fuel and the drag reduction,

938
00:42:20,390 --> 00:42:21,870
so they were quite
a great innovation.

939
00:42:23,540 --> 00:42:25,000
And they look cool,
as my boss says.

940
00:42:26,180 --> 00:42:27,690
Thanks.

941
00:42:30,030 --> 00:42:31,870
(man)
I noticed that you use
a lot of scale models

942
00:42:33,180 --> 00:42:34,180
in these wind tunnels,

943
00:42:34,660 --> 00:42:36,779
obviously 'cause you can't
fit everything in there at once.

944
00:42:36,780 --> 00:42:38,810
But at what point does
the scaling sort of interfere

945
00:42:39,660 --> 00:42:41,149
with the veracity
of the measurement

946
00:42:41,150 --> 00:42:42,330
that you're going to be taking?

947
00:42:43,030 --> 00:42:45,719
(Christina)
So there's this special number
called the Reynolds number,

948
00:42:45,720 --> 00:42:47,450
and it's rho times
the dimensional length,

949
00:42:50,360 --> 00:42:52,300
the size of it, divided
by dynamic viscosity, mu.

950
00:42:54,780 --> 00:42:56,690
So, if we're able to match
this Reynolds number,

951
00:42:56,840 --> 00:42:59,180
you actually get the same
flow field around these models,

952
00:43:00,390 --> 00:43:01,870
and we're able
to have smaller scales.

953
00:43:03,180 --> 00:43:04,570
Can you imagine
trying to test, say,

954
00:43:05,660 --> 00:43:06,660
a live, real-scale 737

955
00:43:08,000 --> 00:43:09,480
and how much energy
it would take for us

956
00:43:09,630 --> 00:43:11,030
and even to fit
into a wind tunnel?

957
00:43:12,480 --> 00:43:14,600
Which is why we go down
to smaller scales to test these.

958
00:43:15,780 --> 00:43:17,719
A lot of the time, we actually
don't test in full scales

959
00:43:17,720 --> 00:43:19,300
in wind tunnels
'cause they don't fit.

960
00:43:19,660 --> 00:43:21,480
But all our validation's done
in small scale,

961
00:43:22,060 --> 00:43:23,600
and then we go
into flight configuration

962
00:43:23,780 --> 00:43:24,780
for the final test.

963
00:43:25,420 --> 00:43:28,180
That was a good question.
Thank you.

964
00:43:30,390 --> 00:43:31,839
(woman)
If there's
no further questions,

965
00:43:31,840 --> 00:43:33,660
please join me again
in thanking our speaker.

966
00:43:35,000 --> 00:43:38,000
[applause]