Quiet Supersonic Flight Over Land – Lowering the Boom

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[MUSIC] Welcome to the first program and our webinar series NASA aeronautics,
aviation at the leading edge. I’m Scott Terry, Director of the Aviation
Institute at the University of Nebraska at Omaha and Director of
the Nebraska Space Grant Consortium. NASA Space Grant program has
consortium of universities and other partners in each state plus
Puerto Rico and the District of Columbia, which are focused on STEM education,
workforce development, and research inspired by the exciting
work of NASA’s Mission Directorates. I want to thank all
Old Dominion University for hosting this webinar series in
their fantastic facilities. Yes, we’re called Space Grant but
we have members across the nation who work on aeronautics
aviation-related challenges. So for this series, we’re going to focus
on the first A in NASA, aeronautics, the study of science of flight. NASA has made decades of
contributions to aviation safe and sustainable by reducing emissions,
noise and fuel consumption while enhancing
safety in the National Airspace. NASA developed technologies onboard
literally every commercial aircraft and at every commercial airport in the US. So we’ve partnered with NASA’s
Aeronautics Research Mission Directorate to introduce you to
the people the ideas and the technology driving the ongoing
transformation of aviation. We start tonight with the challenge
of quiet supersonic flight over land. We’ll be answering questions
after our main presentation. Just submit a question, use the chat feature in the webpage
at any time during the broadcast. Please include your first name,
your major, and your university so we can recognize you. Like to welcome Mary Stringer,
aerospace researcher and Corey Diebler x 59 flight dynamics and simulation lead from NASA’s Langley
Research Center in Hampton, Virginia.>>Thank you.>>So Corey and Mary, could you tell
us where you’re originally from and where you attended university?>>Sure. I grew up in New Jersey. I did my undergraduate degree at the
United States Naval Academy in Annapolis, Maryland. And then I did all of my graduate work at
the University of Florida, in Gainesville, Florida.>>I was born and raised in a small town,
Bucyrus, Ohio, and studied aerospace engineering
at the Ohio State University.>>Very good, we’re not falling for that.>>[LAUGH]
>>When I first heard we were discussing supersonic flight, I immediately
thought about the previous efforts. The Concorde, which most people
are familiar with, the Soviet TU-144, and the American SST program in the 1960s. Can you remind us what
happened with those programs?>>Sure, while they were pretty
advanced for their time, they were also plagued
with quite a few issues. To start with the American SST
program never actually was built, so that would never got off the ground. As for the Concorde and the Soviet TU-144
they had quite a few issues. The first is that they were noisy,
they were loud, they legally weren’t able to fly overland. So their routing was subsonic overland and
could be supersonic only over water. So their routes were limited
in their usefulness. The second issue was maintenance. Unfortunately, they had quite
a few pretty tragic mishaps and just constantly plagued
with maintenance issues. The last was fuel efficiency,
and this was a big one. Back then the the engine
technology isn’t what it is today, it’s actually come quite a long way. But because it was not fuel efficient,
it made it very expensive to operate, which ultimately meant that
the passengers who were using this for commercial service, were more or
less unwilling to pay these lofty fees just to fly commercially supersonic and
get there faster. So, Concorde last flight was was in 2003. And so for like the last two decades, it pretty much has not been a big player
in our aerospace industry, right.>>Very good. So that was then, this is now. We want to know why NASA is exploring
supersonic flight today and what’s changed. Mary and Corey are here tonight to
tell us about this in some detail, but we’d like to show a video first, that shows the key components of
NASA’s quest to quiet the boom. [SOUND] [MUSIC] That’s certainly impressive. I guess it begs the question, Corey, why
is NASA exploring supersonic flight now?>>Well, the truth is that we’ve
never really stopped exploring supersonic flight. But I guess the difference being now,
we believed that we have the design, tools and methodologies necessary to bring
down the sonic boom to lower levels. Mary had just mentioned that
Concorde was only able to fly super sonically over the ocean. [COUGH] Excuse me, and that was primarily due to the sonic
boom that it created when it was flying. For those of you who’ve not heard sonic
booms, it is like a cannon going off. I mean, they can be very startling. They rattle ceiling tiles,
they set off car alarms, and when you’re not expecting them,
they’ll make you jump. And so that was the prohibition, I guess,
against the Concorde flying supersonic. Like I said, now we have the tools and
the design methods to bring that down to where we think that we can get
a necessary rule change to do that.>>So can you tell us more specifically
what the X-59 mission is, and how that fits in with NASA’s plans?>>Sure, so the X-59 is
going to be NASA’s first manned experimental airplane
built from scratch in, gosh, several decades now. And the goal of the mission
is going to be to fly it, demonstrate that we do have the technology
necessary to lower the boom. And collect the data to provide to
the regulation agencies, the FAA, the International Civil Aviation
Organization that we can actually achieve this goal of ours of reopening
the super sonic commercial industry for passengers like you and me and for
the US Manufacturers to lead the market.>>Excellent,
I guess another question that I have, and I’m sure others have is,
what exactly is the sonic boom? Can you explain that to us?>>Sure, so it is a popular misconception
that sonic booms, you only hear a sonic boom when an airplane initially breaks
the sound barrier, but that’s not true. Any airplane or any object moving through
the atmosphere faster than the speed of sound will create shock waves. So the picture that you see on
the screen right now is an actual image, it’s something that they’ve been
working on out at NASA Armstrong. To take pictures of the shock waves
of these airplanes as they fly. So this is a T-38 flying
supersonically and you can see all the shock waves
that are coming off of that. They’re coming off of the nose, the tail,
the wing, the the cockpit, canopy, any little bump on the on the vehicle
will create these shock waves. And so,
what happens with these shock waves, as they travel down towards the ground,
they start to pile up one on top of another, and that just kind
of amplifies their strength. So for example, on this slide here, the it’s a Concorde-like design up top
that’s creating these shock waves. And you can see as they come down,
they pile up on top of each other and so you end up with two shock waves,
one on the front end and one on the back. They call it an N wave because that signature on the ground
kind of look like an N. But it’s that very sharp
rise on the front and the back that creates this booming
noise as it passes over our eardrums. And so
that’s what we’re trying to alleviate. So with our design methodologies
that we have now, we’re able to keep those shock waves from coalescing
and piling up on top of each other. And so, when that happens, the individual shocks weaken as
they go down towards the ground. And since they don’t pile up,
they don’t create such a sharp rise. And so you end up with a more
gentle thump or something that I’ve heard people describe it as a door
slamming in the distance or rolling thunder,
something along those lines.>>Great, so I think we want to start
digging into the some of the technical details. And maybe to start that,
can you tell us more about how the X-59 design is going to help
control the shape of that sonic boom?>>Sure, so we’ve done a number of things on X-59 to manage the the shape
of the boom and the magnitude. One of the things you’ll
see on these pictures is this vehicle has a very long nose. And that pushes that initial front
shock further out in the front which helps it,
the other shocks don’t pile up on that. It also has canards, which are the smaller wing-like wings just in
front of the cockpit. And those are there to help the vehicle
trim at the right angle of attack, the right deflections
at the crews condition, because those affect the boom as well. This vehicle has both an all
moving stablator on the back end, as well as a T tail. Which looks like a small,
horizontal tail up high. And that T tail is another
feature that allows us to tailor the sonic boom
coming off the aft end. It also has an engine that’s
mounted high and up above the wing. So that way any shocks that come off
of that engine inlet are reflected by the wing and go upward rather
than down towards the ground. Though you can’t see it in this picture,
on the underside of the vehicle, there are a couple of boom bumps
that are kind of variables. And we’re going to have the ability to
change those, the different shapes as well that that can help us further tailor that
sonic boom coming off of from underneath.>>That’s great, so,
reducing the noise or the sonic boom, how quiet is quiet enough, or
how quiet is this aircraft need to become?>>That’s a good question, so
the Concorde created a sonic boom in the order of 109 PLdB and
that’s a perceived loudness decibels. Most fighter aircraft these days
are on the order of 100 PLdB. On the chart that’s that’s showing right
now, you can see that there’s a threshold for discomfort up around 200,
loud music around 100, traffic around 80. And so the goal that we’re shooting for
with our aircraft is 75 PLdB. And that’s based on some historical
studies that NASA has done that we believe that if
we can achieve 75 PLdB, that that’s where what would
be acceptable to the public. That we’ll be able to
present that data to the FAA, to the regulation agencies
to get the rule changed.>>Great, so Mary I understand that X59 is
what’s called a technology demonstration, as distinct from a prototype. Can you tell us a little bit
about what that means and what are the implications for the program?>>Yeah, sure. The important thing to remember
here is that what we are building is a demonstrator. It’s not scalable. It’s not something
the public will ever fly in. It’s not a prototype at all. So that will be left up to the industry
members to develop their own aircraft. Will the tools that we’re developing
today help them create their prototypes? Yes, definitely. That’s one of our big missions,
is to be developing the technical tools to design aircraft that are low boom. So those will be used by industry,
but this particular aircraft is used only to create essentially that
database to turn over to the FAA and IKO to kind of redefine what
the regulation should be. So it’s a demonstrator, not a prototype.>>Great that’s really interesting. I think one of the things, or a number
of things that maybe you can help us understand or that there’s got to
be some unique challenges with this type of aircraft, the X-59,
can you talk a little bit about that?>>Yeah, definitely. Of course there are,
essentially our mission is one thing, is to lower the sonic boom signature. So we optimized over that. So the outer mold line of the aircraft,
which is essentially the physical shape of the aircraft,
as Cory did a great job of explaining. We optimized over that, but unfortunately there was some less
than ideal things that fell out. And two of those were the forward
vision on the aircraft, as well as the stability of the airplane. So as you can kind of see
in the first picture, the cockpit,
the glass is over the pilot’s head. So yeah there is a cockpit and he can see
out it, but his forward vision is very, very limited. So to deal with that, NASA has developed something
called the eXternal Vision System. You’ll see it in
literature written as XVS. But it’s a series of sensors and
displays and image processing technologies all combined to create this pseudo
out the cockpit front view so that the pilot can safely maneuver in the
national airspace as well as land safely. So this is not a safety critical system,
but it is definitely a very useful tool for
the pilots to continue to fly safely in this aircraft
that has such limited forward vision. The other thing that I mentioned
was the stability of the aircraft. So the shape itself is optimal for
the boom, but it’s not optimal for
stability and control. And that’s a pretty important thing,
because that points directly to safety. So because it is unstable, aircraft in the past were more or
less stable naturally. And you were able to use mechanical
controls to deal with that. But today we have to use more
complex fly by wire digital controls to control this airplane. And that essentially means that those
mechanical controls where the pilot puts the input into the stick, and it gets
transferred to the control surfaces. Being modified only by mechanical
means is is no longer going to control an airplane like this. So you need a computer in the system,
and that’s what fly by wire means. That computer contains algorithms which
take that input,what the pilot’s commands are and then they modify it so that
The output of that airplane is stable, and it moves the control surfaces as such. So those flight controls,
it’s very important, as you can see, that they
are essentially tuned and very robust. And the best way we can do
that today is by designing or making sure that our plant model is as
accurate as we could possibly get it. One of the difficult things here
is that we’ve never designed an airplane like this. Usually when you go to create an arrow
database of coefficients of forces and moments, you’re able to look at a lot
of historic aircraft and say okay, even though we’ve done some testing we
feel pretty good about it because it matches pass data,well,
we don’t have that capability. So NASA and Lockheed Martin
together have extensively tested this air foil this aircraft in
the wind tunnels and using CFD, which is computational fluid dynamics. And we feel that we’ve created this
database that it’s going to be pretty close to what the actual find that the
actual air aircraft will performance in terms of coefficients of forces and
moments. So, that way we’re able to feel
pretty secure when we design these control laws around the dynamics
of the airplane that this will ultimately be a safe and
stable aircraft for the pilots in it. The other thing that is important to
mention is that the sonic boom levels are very sensitive to a lot of the flight
parameters, such as angle of attack, the control surface positions,
the altitude mock, things like that. So having a very robust flight
control system including autopilot, it’s turns out to be really necessary
to do this kind of flight testing that we’re planning to
do with the aircraft.>>That’s great, Cory, I guess the next
question is where clearly works being done to overcome these
challenges to deal with the sonic boom. When is this airplane going to fly and
what’s the what’s the plan for testing it?>>Sure, so we’ve broken our mission
up into three distinct phases. Phase 1 is our aircraft development phase. And so we actually just completed our
project CDR out in Palmdale earlier, well, I guess last month mid September. And so now we’re moving on forward
completing that design and fabrication of the airplane,
actual airplane has begun out in Palmdale, California at our Lockheed
facility out there. So that’ll continue the airplane
will be put together in our initial flight we’re targeting 2021. And that’ll be our check out
flight where we essentially go out to make sure that
the aircraft s safe to fly, that it handles the way that
we predicted it will be, we expand the envelope checking for
loads flatter. Again, kind of safety making sure
that we can operate to the speeds and to the altitudes that we want to. So when that is done, we anticipate phase 1 might take
about nine months to complete. That phase will move into phase 2,
and that phase two will also be flown out at Edwards,
California out at NASA Armstrong there. And during that phase will focus
on the sonic boom measure and really kind of characterizing what kind
of sonic boom levels we are seeing not only on the ground but also in flight. We’ll have additional airplanes
up there with sensors on it that can measured the sonic boom
at different levels different distances from the aircraft itself. And we’ll continue to learn more
about how the airplane flies and how we want to fly it for our phase 3. So then, in phase 3,
which we anticipate will be in 2023 that’s when we’ll do our
community response flights. And for that, that will be a fun one
because we’ll take the airplane out throughout the country and
fly it over select communities. And the goal there is to collect this
data, create this database that then we can deliver to the regulation
agencies to get the the rules changed. But essentially, what we’ll do is we’ll
fly it supersonic and lay down sonic booms over the towns, the communities,
the cities that we’ve selected. And we’ll take survey the people, see how objectionable they thought
those sonic boom levels were. And there’s actually a good chance
that they won’t even hear it. As people go about their daily lives and
walking around through the cities and and there’s traffic going up and
down the streets, there’s a good chance that they won’t
even notice that there was a sonic boom. But if they do, I said it’ll be
more along the lines of thunder or something that doesn’t startle them and
doesn’t set off their car alarms.>>So I guess I got a couple
additional questions and I think we have time for that. So you mentioned Lockheed Martin,
clearly some industry partners here and maybe you could talk a little bit about
how NASA interacts with industry partners, both from your positions as researchers,
but also how those industry partners
play a role in what you’re doing.>>Yeah, sure. With regards to Lockheed Martin, it’s
obviously a clear contract with them and they are doing a lot of the design work
and it’s kind of a shared effort and they’re ultimately building it. We’re also analyzing everything they do,
but a lot of the tools that we’re using to do the development weren’t just
developed specifically by Lockheed Martin. It’s, work that NASA has done with Boeing,
through extensions of HSCT at the high speed,
civil transport and, and all of that, to essentially learn how to shape
airplane and the optimizations for that. Gulf streams been a big participant
in the propagation models. So how those sonic waves
translate down to the ground and building models that essentially
properly show the difference between the near field, what the signature
is right around the aircraft, as it propagates down and
then what you hear on the ground. So Gulfstream’s been a big
participant in that as well. So, what do you think of that?>>So, somebody’s got to have
to fly this airplane, right? And so I know NASA has test pilots and
there are other test pilots in the industry is the test pilot need to be
prepared differently to fly this aircraft?>>Not too much. So we have three pilots right
now that will be flying. One is a Lockheed Martin, test pilot and
he’ll be the first to fly. This is the Lockheed under contract for the phase one and
envelope expansion flights. And then we have two pilots out at NASA
Armstrong that will be flying it as well. And each of them has flown supersonic
airplanes before not quiet ones, but but I think on a routine basis are going
faster than the speed of sound. Mary and
I both work in the the controls and handling qualities flight
dynamics area of the airplane. And so, we’ve attempted done
our best to make sure that this airplane is pretty easy to fly and
handles pretty well. So there shouldn’t be anything too
out of the ordinary actually when it comes to flying this.>>So I’ve got one more question for our
technical session, and that is that this aircraft is really, like you said
a demonstrator that hopefully gets us to a commercial supersonic transport,
which we think would be a lot larger. Is are there are there implications for how you scale this up to a larger plane
that can carry people and carry cargo.>>So one of the things they have
made sure is that is that there is traceability. So even though it is a demonstrate or not a prototype as we talked about earlier
There has been a requirement to show that the sonic boom signature from
a smaller aircraft is traceable. So it is something that they
are very conscious of and have been making sure that it’s
been maintained as a requirement. So yes, we do expect probably
the initial wave to be smaller aircraft that
hit the market first. But with the commercial aircraft, the much
larger ones that you’re talking about, right behind them. So yes, traceability of that sonic
boom signature has been a requirement. And it’s been something that
they’ve made sure is going to work.>>But it is a challenge, that
scalability, scaling up is a challenge. So this airplane is about 100 feet long or just shy of 100 feet long and,
I think, 30 feet wide. And so yeah, when you when you
scale it up, and that’s just for the One Pilot in this demonstrator. As you scale it up, here are additional
challenges, structures being one, and flexibility,
that makes it a bigger challenge. So like Mary said, it will start off
with with kind of smaller aircraft. And as as we learn more,
as the the companies learn more, then it’ll grow to, to where we can
put a couple hundred of us on there.>>Very good, so we’re going to
shift gears in just a moment. But before we do, I want to give you
another reminder to submit your questions using the chat feature in your webpage. Again, please include your first name,
your major, and the university that you attend. Really want to take advantage of Corey and Mary being here to help us understand
how they got to where they are. So could you tell us a little bit
more about your career journey?>>Sure, after I graduated from
the Naval Academy, I took my commission in the Navy as a naval officer and
the aviation community and served proudly. After I got out,
I went to graduate school. I started working on my PhD at
University of Florida, as I had said. Worked on that for quite a while and
when I was all but dissertation, the opportunity at NASA, I heard about it. And I applied for the position and
fortunately got it. I was a little nervous about leaving
when I was all but dissertation, to work on my dissertation part time and
work full time at NASA. And it certainly has been a huge
challenge, but it’s manageable, it’s doable. And I’ve been fortunate enough to work on
commercial supersonics since I came on board at NASA Langley. As of late, I have kind of started looking
at a little bit of some internal research, putting together a proposal for some uncertainty analysis related
to CFD and wind tunnel testing and propagating that dispersion model for
the aero database, essentially. I want to look at some, essentially,
math applications there. And so that’s kind of something that I’m
looking at in the near future as well.>>Great, now Corey,
you’ve had a slightly different path.>>Yeah, so when I was at Ohio State,
I learned of the opportunity for an internship at NASA Glenn,
and so I did that. I think it was in between my junior and
senior year at Ohio State. And that really kind of opened the door
for me in terms of working for NASA. And then when I graduated, I hired on with NASA full time out at
NASA Armstrong in Edwards, California. And so I worked out there and got to work on some flight
projects on the aero side of NASA. And then from there I
bounced around a little bit. I moved to Florida and worked at NASA’s Kennedy Space Center on
the on the shuttle program down there. And then I came up to NASA Langley,
where I worked on another rocket program. We did a test launch of the Ares I-X
rocket while I was at NASA Langley. I did a nine month detail at NASA
headquarters in Washington, DC. And then when I came back from that, I started working supersonics and
got involved in X-59.>>So Corey, you did a NASA internship,
is that correct?>>I did.
>>Can you elaborate on that a little bit more? At space Grant,
we’re big fans of internships at NASA. So maybe you can share some
of your experience with us.>>Yeah, absolutely, so
it was a great experience. I was working the tail plane icing
program there at NASA Glenn. They have a wind tunnel where they can
blow water in at freezing temperatures and build up ice formations on on wings,
and tails, and helicopters, and all kinds of stuff. And so I was working in there. But more than anything,
it was a great, like I said, kind of opened the door for me. Made some connections, got to know people,
got to know what NASA was all about and how things work there. Which really was an advantage for
me for when when I graduated and looked to hire on full time with NASA,
or anywhere really. So yeah, I highly recommend the internship programs
as something to definitely go for.>>So and
I know Mary didn’t do an internship but she’s been a mentor to interns. And I think maybe from that perspective,
how do you see internships playing a role in the personal professional
development of young people?>>Yeah, definitely,
this last summer, Corey and I actually shared three interns to
work on a X-59 related project. And they actually came from
all different backgrounds. One was computer science,
two of them were aerospace engineering. But but
their interests were very different. And I feel like we were able to,
or I should say, they were able to have access to people
like myself who are more recent hires and people who have been there for years. And to kind of learn how the process is,
like when and what happens within the wall at NASA. And have a fairly relaxed
mentorship relationship with researchers who are,
doing cutting edge work. So I think I think our interns
enjoyed their time this summer, and I hope they would agree. But yeah, I mean, the amount of contacts they made and
what they actually got to see. Corey and I were pretty proactive about
just taking them to everything we possibly could and getting them in
to see all sorts of things. So I think it was very eye opening for
them. And like I said,
they made quite a few contacts.>>Great, so it’s pretty clear from
hearing what Corey and Mary work on and the project they’re involved in that
they really love what they’re doing. And maybe you could talk
a little more specifically about, you’ve touched on some of this already,
but what really inspires or motivates you? What do you really love
about working at NASA?>>For me, it’s, I think,
when left to my own devices, I’m a pretty theoretical person. Math is what kind of
drives how my brain works. But too much of one thing is a bad thing,
so NASA’s great. I work on this very
applied research project. But at the same time, I’m allowed to kind of pursue the more
theoretical things that I’m interested in. And that’s not always true out in certain
sectors of industry, if you will. At NASA, you’re not only allowed, but supported when it comes to kind of
allowing yourself to look at the different aspects of being an engineer and
a researcher. So I love that about my work.>>Corey?>>Yeah, I kind of more or
less second what Mary said. I’d say the best thing is just all
the different projects that I’ve got to work on in my career. I’ve been very fortunate. I’ve worked on a number
of flight projects. Been in the control room for a flight
project when I was out at NASA Armstrong. It was a modified F-18. Was in the control room for
shuttle launches at Kennedy Space Center. And the rocket that I worked on,
that I mentioned before, and now X-59. So just all the the varied projects and all of them just super interesting
that it’s hard to get bored, I guess.>>It’s true.>>Right, yeah, great. So I know we’ve got a variety of
students from around the nation, if not around the world, watching tonight. And so we’ve got some engineers,
technologists Designers, project managers,
computer programmers and so on. If you could help us or maybe help them, what you wish you knew
then that you know now. In other words, what kind of advice can
you give some young people out there who are aspiring to move into roles
like the ones that you have now?>>Yeah, sure. I think my biggest piece of advice and something I learned from experience
is don’t put yourself in a box. I’m an electrical engineer, and
I know when I was starting graduate work, I knew I wanted to work in aerospace. So I was torn as to whether that meant
that my graduate work should be in aero or if I should continue as
an electrical engineer. And I didn’t really have anyone kind
of telling me one way or another. And so I was constantly concerned
that I wasn’t going to be able to get the position that I wanted at that moment
if I stayed as an electrical engineer. And I guess my advice is
don’t put yourself in a box. Follow what you are interested in,
make sure that your education is broad and that you’re good at it. And then ultimately, you will have a lot
of options down the road as your ideas change about what kind of application of
engineering, what you’re interested in. I know that’s true for controls. As long as you understand
the mathematical theory behind controls, you can work in a lot of
different application areas. And if you’re like me,
you weren’t blessed at knowing exactly what you wanted to do at age 18 or
even 22, for that matter. So if you don’t put yourself in that box,
if you don’t create a formula for what you think needs to exactly happen to get your
dream job, I think you’ll be better off. Like I said, just don’t don’t create this
notion of what you think you have to do. Just follow what you’re interested in and
ultimately, I think you’ll find you
have a lot of opportunity.>>Great, Corey?>>Yeah, again, I think I’d
echo mostly what Mary had said. I think some of the most fun
that I’ve had in my career are the times where I wasn’t really
sure how it was going to go. Taking that step maybe
a little bit further, getting outside of your
comfort area a little bit. When I moved to California,
I came from a small town in Ohio. And moving to California was
a big deal for me at the time. I think the moving truck showed up and
I had a TV and a mattress. And that’s what I went to California with,
not really sure what I was getting intto. But it was great experience. It was a great experience. I learned a lot from that. Every move that I made across
the country coming from NASA Armstrong to Kennedy Space Center,
just even though it was still within NASA, such a different experience. Those kind of of things help
you see the bigger picture and really broaden your perspective on things. And so my opinion is, it’s been really
good to change things up like that. And again, that’s one of the things that working
at NASA has really allowed me to do. And so I’d say, don’t be afraid
to do that even, like Mary said, even if it’s things that you’re not
quite sure that you’re qualified for. I’ve known a lot of people who’ve
applied for jobs, who have jobs, who tell me that I’m not qualified. I don’t meet all the requirements that are
on the job description, but none of us do. So go for it, and yeah,
you learn a lot that way.>>Great, so I think,
learn broadly and take some chances. And your career can take
you some amazing places. So we’ve got a lot of questions from the
audience, which I appreciate very much. If there was a prize for the first
question, it would go to Braden Rickard, majoring in aerospace engineering
at University of Alabama. Unfortunately Braden, there’s no prize for
the first question, but it’s a great question. If you are a pilot of an aircraft
that surpasses the speed of sound, will you also hear the sonic boom?>>No, you wouldn’t, you wouldn’t. So the sonic booms are all
going on all around you. But since you’re sitting there, none of those pressure waves
are going across your ear. So I’ve talked to some
of these pilots before. And they say, if I didn’t have that
little meter, that little gauge in the cockpit that told me I was going
supersonic, that they wouldn’t know it. So no, unless there’s a difference
in engine noise, you would not. You wouldn’t notice it and you
definitely wouldn’t hear the sonic boom.>>Yeah, you’d also be on your ears.>>Right, so yeah, ears.>>It’s so loud that you
wouldn’t want to be hearing it, even if you did hear the boom,
you wouldn’t want to be hearing it.>>So another question actually also
from University of Alabama, from Andrew, majoring in aerospace engineering. Which major structural component
required the most design changes from those found in conventional aircraft?>>I don’t know that I can pinpoint one, since neither of us were
designers of the outer mold line. But I can tell you that a lot of the
recent changes to the outer mold line that we discussed earlier has been the
placement of the engine, essentially, and the inlet. Because I think it required a lot
of optimization in that area. The nose was an easy change. They knew kind of what
they needed to do there. And the same with the back end,
the tail, the aft deck. I think they kind of saw what the solution
was and it just took some optimization. Whereas with the placement of the engine
and then the shaping of that nozzle or the inlet and the nozzle, I think that
probably gave them the most pause and has made them readjust it
multiple times recently. Maybe you can add to that.>>Yeah, I’m going to take a shot at this,
because I think that some of our structural friends will-
>>[LAUGH]>>Get on our case if we don’t. But I’m looking at some of
the pictures that we have here. I don’t know if we have
a good picture that shows it. But on the nozzle coming out of
the engine there’s a kind of I guess an aft deck that helps the shield and
some of that noise coming off the aft end there from the engine and
block those sonic booms. But because that is there in its location, it makes it tricky from
a thermal standpoint. Because it’s all the hot gases coming
out of the engine right there. And so I think that has been a challenge. So we’ll check with our structures
group when we get back. But I’m going to go with the aft
deck being the biggest challenge.>>Okay, so
we’ve got a question from Isaiah, who’s majoring in aerospace engineering
at University of Michigan, Go Blue. Have you made any discoveries or advancements with Quest that have
applications in subsonic flight? If so, have you worked with any
companies other than Lockheed to develop these further?>>Honestly,
the mission is not related to subsonic, so-
>>Yeah, that->>That’s not what this technology developer is for.>>The XVS probably has multiple applications-
>>Yeah.>>That can be used
beyond the supersonics. And so there’s that. I don’t know that we’ve worked,
aside from that, I’m not sure that we’ve worked
with any other industry partners on any of the designs
from Quest in the subsonic world.>>So you have to remember that for
this aircraft, the boom signature is
the number one mission. So if we don’t get that right, then you’re not going to be able
to change the regulations, right? You won’t end up with a database. Which means that you don’t want to add
any additional risk to this project by essentially other transformative
technologies kind of being piled on. So in a situation like this where
you already have considerable risk, are we going to get the PLDB right? You tend to not want to make the controls
a research project or some structural. You tend to want to focus and
make sure that you get the one thing that will matter in the long run on
this particular aircraft, right? So I think that’s kind of what
drives why we’re not doing a lot of interesting subsonic-related projects.>>All right, so guys, yeah, I think what they’re saying is if you’re
not going fast, it doesn’t matter.>>[LAUGH]
>>I’m not sure, that’s what I got from that. So Jesse, chemical engineering
from Texas A&M University asked, what is the PLdB of a common twin-jet
airliner, such as the Boeing 737?>>That’s a good question.>>That sounds like a quiz question.>>That is a quiz question,
I’m not sure I can answer that. The PLdB is a measure, it kind of differs
from a regular decibel measure in that it’s geared more towards
short-duration sounds. So like a sonic boom,
something that’s a very, very sudden impulse is the PLdB scale. It’s a very good question, I don’t have
a good answer for that, I’m not sure.>>Okay, that’s fair enough, I think. This is a little different question, but I think it’s one that’s probably
on a number of people’s minds. Ryan, who’s in planetary science
from Hampton University, asked, there’s a lot of public interest
in dealing with the climate crisis. And air travel is often seen as
wasteful when there are other means of transportation and telepresence. What kind of fuel efficiency might be
expected with supersonic aircraft?>>Well, this particular aircraft,
again, it’s not a prototype. So obviously, while we didn’t want to be wasteful, that
wasn’t the main thing we optimized over. But there are other projects at NASA
that are focusing on making sure that future supersonic aircraft will have
more fuel-efficient capabilities. And just like I said, we’re very aware of what caused
the downfall of the 1960s efforts. And the big one was fuel efficiency and its impact to cost and
climate, the environment. So while we’re not
the ones working on that, be assured that there are projects right
now that are very focused on that.>>Great, great, Cooper,
a aerospace engineering student, University of Alabama asked,
at what altitude will the X-59 cruise? At what altitude will it create the boom? I guess he’s trying to get
three questions in for one.>>[LAUGH]
>>What is the optimal altitude for deafening the sonic boom?>>So that’s a good question, so X-59, our design cruise condition
is a Mach 1.4 at 55,000 feet. The airplane itself is kind of
tailored for that condition or the condition for this airplane,
they kind of go hand in hand. And as you vary from that, then it
seems to be almost any direction you go makes the boom louder,
very few of them make them quieter. As you do go up and the shock waves have
further to travel to get to the ground, they do have more time to weaken, I guess. Atmospheric conditions
also play a part in that. So it really depends on the airplane
design as far as the optimum altitude to fly at but, for us,
it’s 55,000 feet, Mach 1.4.>>Okay, got another question
from University of Alabama. It seems like maybe there might have
been some extra credit offered here or something. But Anthony in aerospace engineering asks, how long have the two of you
been working on the X-59? And how many hours do you put into it,
roughly, per week or a total? Maybe just a good kind of question
about the workload that’s involved with a project like this and
the roles that you’re playing.>>I can say that Corey and I happen
to both be on the project full time. So as government employees,
40 hours a week. But there are times when you have to
put in a little bit of extra effort. And I’d say, most of the researchers
on our project, we just came out of critical design review,
there are some real long days for us. [LAUGH] But the great thing about the work
environment is it ebbs and flows. So there’s long days, and there are days
that are a little bit more relaxed and you can focus on some other
research interests and what not. But yeah, we’re both on full time, and
that is kind of the norm, especially for such a large project like this.>>Yeah, I started working, like I said, at supersonics when I came back from my
Washington, DC, detail, which was 2012. So I’d been on it,
what is that, seven years now.>>Mm-hm.>>Like Mary said, we’re full-time, but that’s not
true of everybody on the project. Some people work part time and dedicate
another half of their time working another project or
other research that they’re working on.>>So I want to ask a question
that you just alluded to, the CDR,
which is a big milestone in the project. I don’t know what you can
talk to us about that, but how important is that in the sort
of the evolution of this project?>>So CDR stands for
critical design review, and it’s a pretty big milestone in terms
of the development of the project. It’s supposed to represent, I’m not
sure what percent design completion, but it’s pretty far along. And essentially, we present to
a review board, making our case for why we believe that we have a design that
we can proceed forward with and fly. Usually, right after CDR,
the manufacturing of the plane begins. In our case,
we actually started a little bit early, we started making some of the pieces of
the actual airplane before we got to CDR. So when we were out there, we got to see
some of those first pieces starting to show up on the floor out there. But yeah, it was a big deal,
a big milestone for the project to get past that final hurdle,
I guess, in terms of program acceptance
to move forward to flight.>>Excellent, so I gotta, go ahead.>>I was going to say, sometimes when
you’re so involved in the design, it helps to pretty much collect
everything that you’ve done and put it in a organized fashion. And big reviews like this, where you’re so
scope locked on the few things that you were working on for
that particular airplane. It’s a good way, actually, to kind of
bring together all of the research that the individual teams have worked on. So it’s kind of effective for us as well, on top of being reviewed
by an external board. It’s a good way for us to take a step and
say, hey, are we where we need to be, what are we worried about?>>We’ve got another question
from University of Michigan. Minji in aerospace engineering asks, what’s the function of the T-tail
despite a normal horizontal tail?>>So the T-tail actually had
two things that were beneficial. I mean, most of our stability is
coming from that all-moving stab, that’s our major control surface. The T-tail doesn’t actually move
with the control stick input. It does move, change kind of a trim
position as we go supersonic. And so it does two things, one is it gives
us a little bit more pitching moment. Not much, but
it gives us a little bit more to get us on that optimized trim condition or
cruise condition. But I think, more than that, it helps
us shape the sonic boom back there. That aft end is kind of a tricky area
to get that sonic boom under control. And that’s just kind of another little
trim tab that allows us to do that. Is really the primary
reason that that’s there.>>Okay, so a question from
the University of Hartford, Eva who is an acoustical engineering and
music major. Why do you use the PLDB scale
as opposed to DBA scale?>>Well, it’s related to the short period
of time over which you’re assessing the loudness of it essentially. There are multiple scales,
especially on IKO, they’ve looked at a couple
different scales. We’re not acoustics people. So you can’t talk extensively about that,
but I’m sure you can find papers on it. But yeah, it has to do with
the fact that this is a very short time period that the noise
is occurring over. And it essentially takes that into
effect with regards to how loud it is, the impact of that loudness.>>I think one of the things we talked
about earlier was the diversity of engineering disciplines that are involved
in a project like this, acoustics and a variety of other disciplines. I mean, can you talk a little bit
about working across discipline in an interdisciplinary, transdisciplinary
kind of project like this?>>Yeah, and we can both take it. It’s challenging but
great all at the same time because it forces you to see how your design and
analysis impacts other areas. I think oftentimes in the university
setting although there’s graduate projects, where you interface a lot more,
you’re so focused on your one thing. And having to work with structures and
aerodynamics people and even propulsion to some extent,
we all impact each other. And you’re you’re forced to communicate or
or perish essentially. So it’s challenging. We’re multi-center,
we’re not just all in one location, and we’re different specialties. So there’s added challenges there,
but I think it makes us better for it.>>I’ve been told that the controls
people are the worst though.>>[LAUGH]
>>Yeah, we’re at the bottom of the totem pole. Everyone makes their changes and
then they say is it still stable? [LAUGH]
>>I say that because Mary and I work in that arena. So yeah we work simulation,
controls, flight dynamics and so we end up taking a lot of the models that
are provided by these other disciplines. Structures, like Mary said, aero,
all of it come together and feed into our simulations that model how
the airplane is actually going to fly. So it kind of forces us to
work with all of those groups. And then beyond that you had mentioned I
think somebody was an acoustics engineer.>>Right.
>>Acoustics research.>>Yeah.
>>We have those propagation models, we have aerodynamicists that do computational
fluid dynamics that tell you where the shock waves are and what the pressure
is right around the airplane itself. And then there are propagation models for
how those shock waves, what they do, how they behave as
they make their way to the ground. Which is a separate discipline and
a separate tool set that does that. So there’s a lot of different
disciplines that come into it.>>Let me see if we, I think we might have
time for at least a couple more questions. Anthony, aerospace engineering
from University of Alabama asks, what is the air foil
shape of the aircraft? Is it standardized like NACA air foils or is it more customized or
a different standard?>>So I think that it starts off
as a NACA air foil and then and then it gets shaped from there. Definitely in this case,
I think that’s true for most aircraft or it’s a blend of a couple
different NACA air foils. In this one a little bit more went into
it because of the low boom design and the shaping of it. A big part of that low boom design
is tailoring the pressure profile over the entire airplane, but
especially the wing as well. So yeah, there’s a lot of fine tuning
that goes into it that kind of takes you away from the original
NACA air foil that you started with.>>Okay, from University of Illinois,
Urbana Champagne, Gabriel, also in aerospace engineering asked, you
mentioned that the shockwave dispersion is affected by atmospheric conditions. How exactly is it affected?>>I’m not sure I can say exactly how,
but I know a lot of it, I believe a lot of it as I
understand it is to the good. So humidity, turbulence effects, those things I think kind of
help break up the shockwave, kind of help reflect it and make it
dissipate as it goes to the ground. Temperature variations,
just anything like that. I think it is kind of similar
to light refracting as it goes through different substances,
water and stuff like that, that kind of of breaks up and
shifts the shock waves around.>>We got a question from Missouri,
Science and Technology, Kristin, majoring in aerospace
engineering asks, can either of you recall a moment where everything seemed
to come together, your Eureka moment? Or would you characterize this effort as
more of an uphill battle the entire time?>>I would say at this point it’s
probably more an uphill battle. Well, I made the comment before where,
especially as controls engineers, we’re kind of at the bottom
of the totem pole. So as everyone else is trying to
figure out their optimization and getting everything right,
we see the impact. And then it’s like, okay, all right,
we gotta go back to the table, is this still okay? Is this still a stable aircraft? Do we need to turn the flight controls? So it’s just a continual process. There’s no aha moment. Maybe for the people designing the outer
mold line where they finally realize, okay, all right,
we’ve kind of zoned in on it. Maybe they had an aha moment. But I think for us, it’s our goal is just
make sure this is a stable aircraft and every time there’s small changes,
are we still there? Are we still where we need to be?>>I think the aero group might have had, I don’t know if I’d call
it a eureka moment.>>Yeah.>>But fighting a challenge that
they saw come up, like my gosh, what are we going to do? But then when they got it solved
there was more of [SOUND].>>Okay, yeah.>>Well, fantastic, I want to thank all
the students from around the country who sent in their questions,
excellent questions. I’m afraid we don’t have
time to cover them all but I think it really spurred
some good conversation here. And thank you Mary and Cory for
your work, your insight, and especially your advice to the students
who joined us this evening and who will be able to watch this
webinar later when it’s posted. Before we sign off,
I want to share some key resources and opportunities with our audience. This webinar has been recorded and
will be available on the series website. Be sure to visit the learn more section. Some of you asked some questions that
we didn’t have time to elaborate on. But you’ll find technical papers,
recommended by our subject matter experts. And information on a wide
range of student and faculty opportunities through NASA
as well as the Space grant program.>>So the Space grant program,
provides a link for you to connect. And if we could show that slide,
a link for you to connect to your
Space grant in your state. As we talked about earlier, every state,
the District of Columbia and Puerto Rico have a Space grant. You can learn more about scholarships,
fellowships, internships, student flight and design programs,
faculty research, curriculum projects, as well as pre-college enrichment
programs for students and teachers. Space grants are a key link
to NASA in each state. So explore these websites and connect
with your Space grant in your state. NASA also offers a number of internships. We’ve talked about some tonight. Paid internships are offered at the
agency’s ten centers and through its NASA internships and fellowships program as
well as fellowships for graduate students. The program website offers more
information on these programs and how to apply. The Aeronautics Research
Mission Directorate also has a University Leadership Initiative. It’s a special opportunity. It’s different from other research grants,
in that it funds teams led by universities, that get
to propose research on what they want. After two rounds of
awards in this program, NASA is engaged with 34 universities so
far. And the key is that
the universities in this case lead, as long as the topic is
related to NASA’s work. So if you’re interested in this,
please look for the solicitations that
are posted annually via NSPIRES. want to remind you that we have
two more webinars coming up. On Thursday October 24,
we’ll explore safe flight for drones, designing a system for
urban mobility. And on Wednesday November 6,
we’ll close out the series, with a look at electrified aircraft, tackling
the challenges of alternative propulsion. Please join us next time when
your host will be Suzanne Smith, Professor of Mechanical Engineering
at the University of Kentucky and Director of
the Kentucky Space Grant Consortium. Good night. [MUSIC]

 

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