You’ve no doubt heard and read a lot about 3-D printing in the last couple of years. Known as “additive manufacturing” in industrial-design circles, the process is used to produce three-dimensional solid objects of virtually any shape from a digital model fed into a special kind of printer.
Several teams have already created 3-D printed airplanes, although not of the size or complexity of any aircraft you or I could fly. Rather, these small R/C models are proving that the manufacturing processes involved in creating a flying machine translate quite nicely to a 3-D printer loaded with thermoplastic powder as it meticulously creates the real thing, layer by layer, including the moving flight-control surfaces embedded right into the design.
After students at the University of Virginia created a 3-D printed drone last year and posted their work to YouTube, the Mitre Corporation hired them to build a plastic plane as part of an Army project to study the feasibility of creating UAVs using this process. Last summer the engineering students produced their second 3-D printed airplane, this one with a 6.5-foot wingspan. Mitre Corp. and Army officials were so impressed that they asked the students to stay on as interns throughout the academic year to create more airplanes.
Of course, building a remote-control model airplane is one thing, but nobody really thinks it’s possible to produce a passenger airplane using 3-D printing techniques.
Or do they?
 Jim Kor's Urbee 2 hybrid |
Jim Kor, a Canadian engineer who is fascinated by additive manufacturing technologies, has just completed the prototype for his Urbee 2, a 3-D printed hybrid car that he claims is as strong as steel yet weighs half as much. The Urbee’s coefficient of drag is claimed to be half that of today’s sports cars thanks to its slippery shape. In fact, the Urbee 2 looks less like a car and more like the latest LSA to hit the market. All it needs are wings, a tail and a propeller.
GE and others have already announced plans to build aircraft parts using 3-D printing. As the uses for the process grow, the costs will certainly come down – perhaps dramatically. And while 3-D printing is time-consuming (it took Kor’s 3-D printer 2,500 hours to weave together the 50 parts that make up his Urbee 2 prototype), the technique also eliminates the time needed to build the thousands of individual parts that go into making a traditional car. When you look at it from this perspective, 3-D printing might actually be faster than today's manufacturing methods.
Besides having fewer parts, a 3-D printed airplane could be adapted to shapes we wouldn't dream of using with aluminum or even today's composites. You could even imagine home-builders getting in on the act as they set up a 3-D printer in the garage and feed it their wildest CAD renderings. Six months later and viola! The proud kitbuilder would have a printed airplane ready to take to the airport wthout ever having to hammer a rivet.
Some are calling 3-D printing a “transformative” technology. Others are saying it heralds the dawn of a new industrial revolution. I don’t know about that, but if somebody wants to build one and the price is right, I wouldn’t mind flying a 3-D printed airplane one day.
All Comments
I think most of the airframe could be printed and then reinforced in high-stress areas. They have already built an operation bicycle in SOLIDWORKS so it's only a matter of time before an entire aircraft can be printed.
The 3D-printed UAV done by the University of Southampton was particularly interesting. Unlike the U Virginia design, which simply mimics a balsawood structure and requires a separate covering material, the U Southampton design created a "stressed skin" that was a genuinely new approach that takes advantage of the unique properties of 3D printing. This new approach created a "geodetic" skin (a 2-D spar, in effect) that could bear structural loads, even though the basic material they used is not a great load-bearing material. It's worth a look.
I'm sure that this technology has serious potential. I'm really excited by it, as the length of this post might suggest :-) I'm biting the bullet and buying a cheap ($500) printer later in the year. After printing out the obligatory novelty items for friends and family I intend to design and construct some RC aircraft components, such as ribs, bulkheads etc. Where I see the real potential is for this kind of tech to remove the vast majority of the fiddly work required to make an aircraft. The actual jobs that the various sections of an aircraft do are pretty simply yet the process of constructing those parts is complex, even with composites. I can imagine 3d printing being used initially to create moulds, blanks and smaller components. In some ways, simply replacing the job currently done by CAD-CAM equipment. As Thomas Boyle alludes above though, the exciting part is when 3d printing becomes viable for creating complex structural components that are either expensive or impossible to make now. Imagine components being designed with only the best possible shape as the priority - no need to worry about the stuff production engineers worry about now. Parts will have many fewer straight lines and load paths will be perfect, rather than easily produced and over engineered. A couple if things I've thought of:
1. Exhaust mufflers designed to optimally reduce noise while minimising back pressure - no more simple tubes with holes in them!
2. Main spars in which every parameter varies continuously to efficiently meet the load requirements and vectors at each point.
3. Wings printed in one piece with flexibility built in so that leading and trailing edges can smoothly flex to modify the airfoil in a bird like way.
It will be a while before the structural properties of "printed" items match those of items produced using existing techniques but the graphs will surely cross before too long. In the interim I bet there will be techniques that involve printing items that then receive further treatments such as curing or hardening.
