[music playing] - welcome to the 2015nasa ames summer series. modular design reduces riskand speeds up technology advancements. also, combining capabilitiesfrom different fields leads to disruptive evolutionof technology. so the combinationof modular design and looking at different fieldsin combination really advances whatevertechnology we're looking at.
today's talk,entitled "affordable airplanes: modular designand additive manufacturing," will be givenby kevin reynolds. kevin receiveddual bachelor's degrees in physics and mathematicswith a minor in electronicsfrom norfolk state university and then went onto get the master's degree, and as you could guess,he did a dual master's degree in aeronauticsand mechanical engineering
from stanford. he's both an nsf and a stanfordgraduate school of business insight program fellow. along the way,he has had many experiences. he's workedat cern in switzerland, bmw technology in germany, hitachi in japan, and golden key internationalin china. he came to nasa amesin 2010 and--
as a civil servant to the-- as an aerospace engineer in the intelligent systemdivision. he has won numerous awards,and obviously, he has won the nasa amesearly career research award that my office handles. so please join mein welcoming kevin reynolds. [applause] - thank you.
thank you.thank you for the introduction. and it's a pleasure for meto have the opportunity today to present to you on a topic that i findextremely fascinating and that is of using3-d printing to make airplanes. so, as you can see, the title is"affordable airplanes: modular designand additive manufacturing." i want to start just by focusingon the word "affordable" because it's somewhat misleadingin that everyone has
their own perceptionof what is affordable, and that perception changesas we go through our lifetime. so instead of this talkfocusing on actually placing a value--a dollar value--on affordable airplanes, we're really going to focus onthe value proposition that can be offeredby two key design elements. and those elementsare modular design and additive manufacturing,also known as 3-d printing. this talk is focused ondemonstrating the use
of those design elementsfor unmanned aircraft but may have future applicationsfor other type of airplanes that are designedto different requirements. i want to also acknowledge and thank the contributorsof this work. the success of the projectwas built on the shoulders of giants,as they say, and so credit is given tothe team that made this happen as well as the advisorsand the mentors
that indirectly or directlyinfluenced the work here: matt fladeland, dr. don nguyen,dr. bob dahlgren, and others. many others. so i wanted to startby framing the talk with an experiencethat i had as an early engineer. in fact, i was actuallya physics major at the time, and i visited a place calledthe pima air & space museum. this place isin the middle of the desert in a placecalled tucson, arizona,
and this is whereairplanes go to die. so, at the end of a lifetime,which is usually determined by when the materialsin the aircraft have reached the fatigue point where they're no longerdeemed airworthy, they are taken to this place, and the low humidityin the desert preserves the partsso that it can then perhaps be reusedin certain applications.
but here in the middleof the desert, there are over 4,000 airplanesthat are just sitting, waiting for the possibilityof having a part here or there salvagedor repurposed for a new airplane. the engines, obviously, are usually taken off firstand overhauled, but this really pointsto a big problem that the aerospace industryis facing,
and that is:how can we extend the useful lifetime of aircraftso that-- by reusing parts,by taking surplus parts, and repurposing them so that we don't haveall this waste? because this wasmy first experience when i was an undergraduatevisiting this place. but 15 years later,i think of this place, and i think,this is the worst place
in the worldfor an aerospace engineer, because who wants to designan airplane that will sit in the desertfor 20 years? well, design an airplaneand then have that airplane sit in the middle of the desert. and so this is reallywhat helped to frame the rest of the discussiontoday. so i look for placesfor inspiration in many different places,but one of the unlikely places
that i found the inspiration was actuallymy four-year-old son. his name is arlo,and he aspires one day to be an astronaut,and he loves playing with legos. and most of us are familiarwith lego design, but the idea of lego design is that you can takevery simple components and rearrange themand reorient them in ways that will producea new product.
sometimes that productcan be bigger than the personactually creating it. to the right,he is using his imagination to show what he would look likeas an astronaut. so this reallyencouraged me to think, are there things that i can doto possibly optimize a process for making an airplaneso that we can extend the useful life of that airplaneand make it-- and reduce the wasteassociated with these airplanes?
so one other process-- processes that i wantto focus on is thatof additive manufacturing, also known as 3-d printing,and the process of 3-d printing is thatyou can take a cad drawing-- a virtual shape--and you can create a three-dimensional objectby depositing layers on top of one another,and the different methods that are used differentiate
between the different types ofprinters used for this method. we want to leverage thisin some way in order to repurposesome of the existing parts of these airplanes. so the innovationlies in the idea that, from an amorphous design space, we can then startcreating designs that are optimized specifically for meetingmission requirements,
and the two fundamental elements are the modular designand additive manufacturing. the advantage of modular designis that we intentionally design an airplane so thatthe parts can be interchanged and we can update the designas the technology matures and as it advances. the main advantagesof additive manufacturing are that you can printand realize a part on demand without having to waitfor something
to be shipped to you. and this can have huge impacton mission requirements that may be in remote locationsand other specific situations such as that. but the real advantageis in reducing the development time,which can then translate into development cost for the specific application. so high-performance airplanesrepresent a big opportunity
for reducing overall cost. you can thinkof the vertical axis being the sticker priceof an airplane. we also call itthe acquisition cost. and traditionally,that acquisition cost is a functionof how high performing the airplane is,and we usually-- we tend to use a metriccalled endurance to describe the performanceof an unmanned vehicle
that could be usedfor a nasa mission. so the longer timethat airplane can fly-- and usually,the bigger the airplane is, the higher the acquisition cost. but what we really wantto focus on is how to make this relationshipmore or less linear, as opposed to exponential,as we see in the plot. so we want to illustratesome of the concepts-- specifically of modular designand additive manufacturing,
using an existing designthat many of you have seen on the way incalled the frankeneye design, and we want to also extractpotential lessons learned for future applications. so we've talked a little bitabout the motivation, so let's diveinto the modular design aspect. so earth science missionshere at nasa are really a core competencythat we have relative to other nasa centers,and earth science missions
really focusedon taking unmanned aircraft, or even manned aircraft,and flying them to parts of the world thatwe want to better understand. and one of the places thatwe want to better understand are volcanoes. this is a picturethat was taken from turrialba volcano in 2003, which is located in costa rica,and the scientists were very interestedin understanding
what type of gasseswere being emitted from the volcanoand how that might impact climate change, for instance. but what we found outvery quickly was that, when we took partsthat were surplus from-- as military hardware, those airplanes were notoptimized for the long endurance that we wantedin our science missions. science missions also tendto want aircraft
that will carry large payloads,large sensors, and fly those sensorsfor long periods of time. we didn't have thatin the current design. so this raises the question:how can we optimize? how can we modifyan existing design so that we can meetthe performance requirements for the specific mission? so one of the waysthat we wanted to leverage technologywas through the use
of additive manufacturing,and this illustration compares the subtractivemanufacturing process to the additivemanufacturing process. typically, in a subtractivemanufacturing process, you start with the material, and your designis largely constrained by what you can manufacturewith that material. carbon fiber, for instance, needs an autoclaveto solidify the part.
and so, because of those typeof limitations, we also are limitedin terms of the final assembly that we hope to achieve. additive manufacturing,on the other end, really allows youat the very early stages of the designto focus on the functionality without being limiteddirectly by the material choice. and so we can generate parts that can then be sentto a printer,
and we can decideon the materials based on the requirementsthat we have. so, for this project,we wanted to take advantage of the factthat we had a good number of surplus uavsthat had been provided to us by the u.s. marines. and we-- the feedstock that we hadfor this specific project was the dragoneye uav,which is also here with me.
this aircraft is designedin five pieces, and those five pieces can bedetached from the aircraft, so you can simplysnap the wings off, which are being held togetherusing bungee cords. and this is really nice, because if you hit a treeor if you hit the ground or you hit something else,then you can absorb the energy in the joint instead ofhaving it break apart. that would need to be repaired.
so, because of the designof this airplane, we wanted to leverage the factthat we had a modular wing, we hada modular payload compartment, which tends to be the nose cone. and we wantedto build off of that by using 3-d printingto create new parts that would enhancethe performance of the existing design. so the five partsare shown here.
the two wing modulesand a center wing pod that holds the batteryand then the tail and the nose are those components. and this design is suchthat it can be assembled in less than five minutesfor the purposes of a typical mission. so, to demonstrate this concept,we took several dragoneye uavs and the componentsthat they consisted of and we looked at waysof rearranging them
or reorienting themin a way that would improve performance. in general, a long, slender wingwill provide the longest endurancefor an aircraft. and so this is an exampleof an aircraft where we attempted to printessentially every part of the aircraft,including the wing sections, the structural componentsas well, the nose cones,and propeller blades.
and this is justto demonstrate the vast variety of partsthat we could achieve using 3-d printing with, really,there being limited material constraintsfor producing a given part. and so you can thinkof this design as being a functionof how many units are attached together. and so you can think of thisas being a 3u design, similar to the jargonthat's used
in small satellite design. and so what we really wantin the earth science community is something that lookslike this. this is the helios aircraft,which was actually a joint project between nasa and several othergovernment agencies, but it was an extremelyhigh-performance aircraft. the caveat, though,was that this airplane wasn't designed for cost.
and socould we replicate something with a similar performancebut with a lower cost-point? so, as some of you may know, the helios did crasha few years back, and it was attributedto some difficulties managing the flexibility of the wingassociated with the helios and how that flexibilitywas accounted for in the control system. now we have toolsthat allow us
to model the flexibilityof the materials as well as the contributionsof the propulsion to the design. and so, going forward, we can look at designslike this. this is a 16u design, which we have the capabilityto model. so when you actually lookat the performance contributions of these individual elements, you can then start to understand
how each componentis contributing to the overall performance. and normally,when we use endurance as the metric for performance,we can look at aerodynamic efficiency,propulsive efficiency, and structural efficiency. this focus is really onthe propulsive efficiency and the aerodynamic efficiencyof the design and the differentcontributions.
in general,when you take a propeller and you have itblow across a wing, it enhances the dynamic-- it increasesthe dynamic pressure on the wing and thereby increasesthe lift capacity of the wing. but the trade is thatit also contributes to drag. so, by makingthese important trades and choosingan optimal wingspan, we can establish the tradebetween aerodynamic efficiency
and propulsive efficiency,which both feed into endurance, which is whatwe're interested in. so say we wantedto design an airplane that was optimizedfor a specific mission, so we could choosecertain parameters, which we choose to optimize for. maybe in this case,it would be maximum range and other--with other constraints
on climb rate and other things. and then we can startto generate trajectories that look something like this,where we're looking at-- the blue line representsthe trajectory that the aircraft would take from the--in the vertical plane. and the green linerepresents the speed at which that airplanewould fly. and so one thingthat we understand very quickly,specifically with this
battery-powered design,is that speed-optimal flight is extremely important,because it's a hit or a miss on the aerodynamic efficiencyof the design. and so this is justan example of how, by understandinghow those different parameters feed into the mission,you can then start to optimize for thingslike maximum energy recovery in the descentof the aircraft. so we talked a bitabout modular design.
now we want to talk moreabout additive manufacturing and the contributionsit can potentially make to the structural efficiencyof a design. so this is a drawingthat was taken of the first powered flight here in the u.s.by the wright brothers. and the unusual thingabout this design was that it wasn't-- it didn't come togetherwith aerospace-grade materials. it actually came togetherwith wires, cloth, and wood--
things that you typicallywouldn't think go inside of an airplane. but one of the things that we knowthat they understood was how to makelightweight structures using those materials,and they had to overcome the challenges of the propulsionand of the aerodynamics by making extremelylightweight parts. the reason why thisis an interesting example
is becausethat same lattice structure now feeds into some ofthe lightest weight structures that we know exist today. this was a structurethat was manufactured using a similar3-d printing method but then electroplatedin metal, and it's shown sitting on topof a dandelion. extremely lightweightbut was manufactured using a very similar method.
so the point of me showing thisis really that this is-- this captures a storyof innovation and why innovation is so important,because as materials change, as technologies change,those allow us to then innovate in ways that weren't possible5 years ago or 10 years agoor 20 years ago. so in order to kind offurther extend the concept that we presentedwith the frankeneye, we invited several studentsand personnel
from many differentbackgrounds-- male, female, white, black,and young and old, republican and democrat... i guess i gotcarried away there. but we invited several students,young engineers, to experimentwith the advantages that we could potentially seeusing these methods. and so we formed teams of threewhich were given the task
of designing their own airplaneto image in highest definition an object that we weregoing to place on the ground using their airplane. and the interesting thingabout the result of those experimentswas that they came up with three differentairplane designs that were really designedto do the same mission. so this goes to say that,many times, we limit the design space to the pointwhere we don't even consider
ideas outside the boxthat may accomplish the same exact missionbut in a different way. the first concept,which is shown here by team hyperion, was designedto turn into a hover, and once it reached a positionwhere it was in the vicinity of the image that was being--the object being imaged, it would,from that hover position, create a 360-degree map, increasing the likelihoodof it catching
a high-definition imageof the object. and team chimaeraand team alconto, they also looked at waysof extending the performanceof the fixed-wing aircraft by adding wingletsand enhancing the flap system. but this all shows that,from a exponential-- from a library of partswhich we created for the students,there is an exponential design spacethat can be explored.
and maybe some designslike the 1910 jacobs design are possible. the next stepof our summer task was to have the studentssimulate how their airplane would performin an actual mission, and so they simulated cruise, they simulated hover,they simulated maneuver conditionsthat would place unusual, asymmetric loads on the wing.
they also simulatedgimbal camera systems for capturing imagesfrom the stationary platform of the aircraft,and they also simulated high-performance,high-lift systems, like the cambered flapssystem which is shown here. and so,through those simulations, they gained a betterunderstanding of how these partswould ideally perform
in the real worldafter being manufactured. so with the resultsof those simulations, they then went tohardware-in-the-loop testing. this is an exampleof testing that was done on a flap systemthat you saw, and we had some of the studentshook their autopilot to the hardwareand actually, you know, for the first time,really see that their design was actually working.
and so they're doingsome flap tests here, and they also do somepower-on tests-- you can see the motor spinning--to make sure that everything checks outin terms of the power-- power systemon the aircraft. so from that stage,we understood that the basic design worked,but we then needed to optimize themfor structural weight and forother performance metrics.
and so this is reallywhere the skill set of the students came in,where they were able to apply their backgroundin aerodynamic structures and other areasto optimize the design. and really what we wantis designs that look more like what we see in nature. a bird's winglooks very interesting in that there's only materialwhere it needs to be in order to maintainthe certain load
that the birdis carrying in flight. and we can also think abouthow this can be applied on the scaleof the aircraft itself using flexible materials,using shape-changing materials that would simulate--that would move us closer towards the directionof what we see in bird flight. another areathat we wanted to explore was how to take a cheap partthat is printed in plastic or in some inexpensive materialand to enhance the strength
of that part, and we lookedat two different methods. one is plating on plastic-- curing on plastic. plating on plasticis also known as electroplating, and it's widely usedin the jewelry industry, in the plumbing industryand many other industries but is now being investigatedfor use in the aerospace engineering industry. and we also were lookingat ways of taking carbon fiber,
fiberglass, kevlar,and using them to moldagainst a 3-d-printed part. the results of thatwere that we showed-- using these different prototypesthat are shown, that we couldenhance the strength of the part byat least three times, making those partsalmost comparable to the strengthof aluminum, which is really impressivefor something
that costs roughlyhalf the cost of an extruded pieceof aluminum of the same dimension and shape. another considerationthat we would need to make in orderto satisfy a mission requirement is understanding how the sensorsplay into that mission and how perhapsthey can be optimized to collect the informationthat is important for the mission succeeding.
and by havinga variety of sensors, which are then themselvesdesign modular to the aircraft, we can interchange sensorsto meet a certain requirement. so we talkedabout modular design, additive manufacturing,and now we can talk more about the specific missionsand the flight operations that are requiredfor getting the airplane into the actual mission. so the airworthiness processrequires that we take parts
and we test themto their structural failure pointto better understand the limitationsof the materials. and we want to make surethat the strength of the part begins to reflectthe harsh environment that we expect to seein certain flight conditions, and so, as a part of thatairworthiness review process, we did static testing,which is where you take a wing and you load itto the point where it strains
and then you lookfor the place where it fails and you try to understandsomething about why it failed and look at waysof reducing the weight so that you can stillmeet the requirements for flight,and this was an example of a static test. beyond that,when you start thinking about putting aircraftinto production or even lookingat larger-size airplanes,
you also need confidencein the models that are used to simulatewhat is happening in the actual physical test. so finite element modelingis very important to improving that understanding, particularlyif you're interested in putting somethinginto production; you don't want to have to doa large number of static tests, but you would ratherhave confidence in your model
matching the static testof the sacrificial part. one of the other questionsthat we wanted to answer, now that we had explored methodsof how to improve the strength of 3-d-printed parts was,"how big of an airplane "can we buildusing the limitations of the existing materials?" and this was a study looking at the differentpossible options for increasing the sizeof the aircraft,
limited bythe root bending moment, which is the integrationof the lift along the wing. and so the answerto the question is reallythat it really depends on what the airplaneis designed to do. most large airplanes thatare long-endurance airplanes are designed to besomewhat of high-altitude, long-endurance aircraft-- the hale uavthat you've seen
certain entities pursuing. but they're really designed againstthe structural limitations of the material being usedin the wing. another alternativeis that you can design much lighter-weightstructures that have some docking feature where there'sminimal load transfer between individual components,
but they can stillshare information. a good example is of sharing of actualphysical material is air-to-air refueling. if an airplane is refuelingfrom a tanker, for instance, there's minimal load transfer,but still, the physical fuel is being transferred,and so i think this is really--has a great potential to produce aircraftthat are just as efficient
as some of the hale uavsbut are extremely lightweight in their design,and this is an unexplored area. another questionthat we had to answer related to the strengthof the part is how would that partsurvive in a crash landing, and so we didcatapult launch tests, which are shown here,where the aircraft is launched with 20 poundsof weight loaded into the center fuselageto simulate
a much larger airplane,and as you see in the test, the airplane just breaks apart,which is great. it confusedsome of the students at first because they didn't knowwhether it was-- it should be thought ofas a failure or a success, but for us,it was a success, because we learned moreabout our launcher system, and we gained confidencein the ability for that launcher systemto handle larger airplanes.
and so this is an exampleof some of the information that we got from ourcatapult launch testing, where the accelerationsfor the launcher matched those that we neededto launch much larger airplanes, and we went through manydifferent iterations of that. so now going to flight,we take our simulations, and then we tryto learn something from the flight testingto calibrate our simulations to the actual datathat we collect in flight.
and so this is one ofthe first flight tests. as you saw previously,it was a little rough coming off of--of the catapult launcher, but luckily by that time,we had de-risked the launcher design itselfso that the real worry was how the airplanewould perform in flight. and this was some videothat was taken. we're locatedin the right corner over there on the groundas the airplane's flying by.
and then the question was,"now that we have "a better understandingof how the airplane performs, can we understand and mapthe aerodynamic improvement to the modelsthat we've been generating?" and by doing that,we can now start to build a way of the computeror the laptop that's being usedas a ground station to directly control the aircraftinstead of having an rc pilot fly the aircraft.
so this is knownas autonomous flight, where we want the airplaneto be flown by the computerinstead of by a pilot. and so we cando certain experiments with waypoint navigation,where we set up the flight path in the software thatthe airplane is going to take, and these are actually the--the actual coordinates of the airplaneas it's following that flight path,which has been set up.
so this is an exampleof how we took that design, which we now hada better understanding of how-- how it flewand how efficient it was to an autonomous flight test. one of the final considerations i want to mention here is that the useful life of an airplane depends also on how it's being used, and we
often refer to this as being the dynamic loading environment of an aircraft. we tend to think that the more material we add to an airplane, the longer a life it will have, but this is kind of counterintuitive to what actually--what we see.
airplanesthat are usually designed to a higher safety factor--meaning more weight is put in the wing--degrade very quickly because they operatein very extreme environments that put certain stresseson the materials. we can also comparewhat we see in the aircraft design worldto what we see in the natural worldwith bird flight, and, surprisingly,some of the most long-endurance
performance birds,like the albatross, are ones that live the longest. so maybe that gives ussome lessons about how we should alsobe more conscious of our health and, you know, what type ofstresses we have on our bodies to live as long as we can. finally, i'm going to end upwith a summary and conclusions. so, the key elementsthat made this project a success were that we were able to
leverage open-source avionics; we were able to leverage modular design reuse of the dragoneye components and rapid prototyping provided to us through the facilities available in the nasa spaceshop. and we were also ableto leverage the use of the airworthiness flightreview board
that is located hereat nasa ames, which walked with usevery step of the way through ourflight testing process. and by taking advantageof these three core elements, we were able to achieve flightin less than eight weeks. this is less than two monthsgoing from a paper design all the way to the final flyingautonomous flight. and not only did we do itone time; we did it twice. so this is an example of some
of the 3-d printed partsthat we came up with, some of them usingthe lattice type designs. this design was done by dave-- by kenny chong,who is a researcher here. and we also were able to takean existing wing that was made out of pink foamand re-create it using 3-d printed parts. this is, essentially, the ideaof 3-d printing a fuel tank, where the airplane can be--
the parts can be designedso that they fit together in a way thatyou just simply add fuel in the middle of the wing, and you can snap iton your airplane and go and fly. and so this wasa major contribution, i think, in the area of the wing designusing 3-d printing. and as i mentioned before,concept of flight, autonomous flight,in less than eight weeks by leveraging the elementsthat i showed earlier.
and so we want to--so this was an extremely successful projectfrom my perspective. the team members thatcontributed and the mentors deserve all the creditfor this, and i'm justtheir spokesperson. but some of that successwas reflected in the media coveragethat we received. we had a very interestinghalloween article that was published with--referring to how we were able
to take these airplanesand put them together almost likea frankenstein monster. and one of the otherinteresting insights that i derivedfrom this project was that in the courseof eight weeks, these student teamsall came up with solutions very differentto the same problem. and if you take all of those--the three solutions and you superimpose them,you get something that
you may have seenon the way in, the super frankeneye, superimposed frankeneye. so the ironic thingabout this design is that it looks very similarto a russian design, actually, that currently holds15 world records. very different scale, very different application, but the pointis that by using
the rapid manufacturingand rapid prototyping approach we were able to kind of startfocusing down on the elements that weremost important for improving performance, and now we were ableto generate a design that we would expectto be an optimal performer if it, say, were scaled upto a larger size. and we also were able to--i was able to meet president obamaon one of his visits,
and i'm very grateful forthe support that was provided with his visit. and the final commentwas that we-- in one of our articles,we were actually given a new word,"frankensteined," which i'm really happy about. and i think peoplejust get the idea that we're trying to reuse,we're trying to repurpose, we're trying to recycleexisting components
but just re-architect themin a different way that improvestheir performance. and we've also seenthat the aviation industry has taken some interestin this. these are some examples--recent examples of how 3-d printingand modular design are being usedin different ways. and we only expectthe future to be much brighterin these areas.
and the potential cost savingsis going to be reflected as we see some of these methodspotentially applied to larger aircraft systems. i would say that this areais an emerging area that needs more research. it needs more attention,but it has the potential to really impact the industryin a big way. so with that, i will... with that, i will askfor your questions.
the next slide is just--yeah. - thank you, kevin.- yeah, thank you. - so if you have questions,please line up on the microphonein the center aisle and ask one question only. okay. - hi, and thank you forthe lecture. very interesting. i was wondering if there'sany crossover with other industriesthat could clearly benefit
from the wholemodular design idea. in other words, like,buildings or automobiles or, you know, subways,you know? has there been any sharingof lessons learned, et cetera? - yeah,thanks for the question. we see modular designall around us. almost every assemblyor complex system that we deal withon a day-to-day basis has many components,but typically those components
are just added togetherusing screws or bolts or in different ways. i think the thing that is uniqueabout this specific design is that we approach aircraftdesign from the perspective that partshave to be interchangeable. we want simple interfaces, mechanical and electricalinterfaces, to make plugging in a new partjust as simple as plugging in a deviceinto a usb drive on a computer.
and so i think we canleverage lessons learned from other industrieslike the computer industry and like many of the otherindustries that produce these complex systemsthat have multiple parts. - hi, i had a questionabout scaling that you toucheda little bit on. so there's a big differencein material properties between what you can 3-d printand what traditionally is used in big airplanes.
so i imaginethat as you go smaller, those kinds of restrictionsget easier to deal with. so did you guys come up withany kind of estimate on how big of an airplaneor what kind of wing loading or some other metricthat you can reach using these kindsof approaches? - you bring up somevery important points. large airplanes, specifically,are in a class of their own because they useparts that are
extremely strongand lightweight. for the purposesof this project, we were really focused onunmanned aircraft because we saw thatas the low-hanging fruit because we didn't--we weren't putting people's lives at riskby flying an unmanned airplane. i think as the materialsthat we see in 3-d printing improve and become stronger,which we expect they will, we can then start to scale upto larger sizes.
one of the aircraftthat we simulated and some of the resultsthat were shown was actually lookingat a 16u design based on the dragoneye concept, and it was approximatelya 60-foot airplane. so at that span,there are also other questions that need to be addressed like,"how do you control it? how do you launch it?" and we think thisis just the very beginning
of where it's going. hope that answeredyour question. - hi, i have a question about the additive manufacturing and the modular design combined. i assume there's some typeof efficiency loss for the structural masswhen you look at adding parts togetherat the joints. can you commentas to what type of degree
of efficiency loss you getby using a modular design? - right, so one ofthe things that is worth noting is when you look at aerodynamicefficiency of aircraft, it really-- aerodynamic efficiencycan be achieved in many different waysby using biplane wings or using non-planar structures. what really matters in termsof aerodynamic efficiency is what the lift distributionlooks like
across the configuration. and we often account forwhat that lift distribution looks like by lookingin the truss plane, which is actually several spansbehind the airplane. so from an aerodynamicefficiency perspective, we can achievesimilar performance using modular designs that havestructurally weak parts. but from the structuralefficiency perspective,
the design of the jointscan be extremely important for the applicationthat is mentioned. in one of the earlier chartsi showed, a self-docking structurecan be designed to have very weak joints,but it just needs to hold the position requiredto maintain the aerodynamic efficiencybenefit. that's just an example. but typically what we see
in most high-altitude airplanedesigns is that those designs are really pushingthe limits of the structure. and i thinkthere are opportunities that perhaps don't pushthe limits of the structure, but more focusedon the control challenges. - thanks for your talk, kevin. could you talk a little bitabout how you would tune the control lawsfor these planes, given one design or the other?
- right, so for the purposesof our project, which was on a short time scale, on a two-month developmentperiod, we used open sourcesimulation hardware, "mission planner,"and "x-plane," to simulate the flightperformance of the aircraft, and those software toolsallow us to build a virtual flight dynamic modelof the design. in a more rigorous--
for more rigorous design,we would actually go into calculating stability based--using stability derivatives and those type of things,but for the purposes of our experimental project, we reliedon the flight dynamic model being createdby the flight simulator. - please join mein thanking kevin reynolds for an excellent seminar. [musical tones][electronic sounds of data]
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