Historically, remote control aircraft were produced much like their early full-sized counterparts. Wooden structures were covered with adhesives and taut fabric membranes. Other techniques later came to the fore, with builders looking to foam and other materials. Of course, these days 3D printers are all the rage, so perhaps one can simply print out a whole plane? As [sahevaantaneja] discovered, it’s not that easy!
One of the foremost problems is the process of slicing. This is where 3D geometry is transformed into the G-code which defines the path taken by the 3D printer during production of a component. Slicer software is generally optimised for working with mostly-solid objects, and some tweaks can be required when working with thin-walled designs.
These challenges come to bear with an aircraft design, which, by necessity must be lightweight. [sahevaantaneja] does a great job of explaining the journey of discovery in which their design was optimised to work with conventional slicers. This allowed the various components to be printed without errors, while retaining their strength to survive in flight.
The filaments in question are VARIOSHORE TPU and LW-PLA, both by ColorFabb. Both filaments have a blowing agent added to the formulation, which releases gas as the temperature is increased. This causes bubbles to form, creating a cellular structure, which decreases the density and increases the flexibility of the printed part. This isn’t the first time that foaming is sold as a feature, but previously it was only done for aesthetic purposes in Polymaker’s Polywood filament.
Before putting the materials through his excellent test procedures, [Stefan] first goes through the process of tuning the print settings. This can be tricky because of the foaming, which increases the effective volume of the plastic, requiring careful adjustment of the extrusion rate. Foaming in the PLA filament reached its maximum foaming at 250 C, at which its density was 44% of the unfoamed filament.
In testing the physical properties, [Stefan] found that the tensile strength and stiffness of printed parts are reduced as foaming increases, but the impact strength is improved. He concludes that the lightweight PLA can have some interesting applications because of the reduced weight and increased impact strength, with 3D printed RC aircraft being an excellent example of this. It should also be possible to change the between layers, effectively sandwiching the foamed layers between solid skins.
Designing and 3D printing RC planes offer several interesting challenges, and so besides being awesome looking and a fast flier, [localfiend’s] Northern Pike build is definitely worth a look. Some details can be found by wading through this forum but there’s also quite a bit on his Thingiverse page.
Naturally, for an RC plane, weight is an issue. When’s the last time you used 0% infill, as he does for some parts? Those parts also have only one perimeter, making this thin-walled-construction indeed. He’s even cut out circles on the spars inside the wings. For extra strength, a cheap carbon fiber arrow from Walmart serves as a spar in the main wing section. Adding more strength yet, most parts go together with tongue-and-groove assembly, making for a stronger join than there would be otherwise. This slotted join also acts as a spar where it’s done for two wing sections. To handle higher temperatures, he recommends PETG, ABS, ASA, Polycarbonate, and nylon for the motor mount and firewall while the rest of the plane can be printed with PLA.
Armed with a variety of 3D printing techniques and years of model-building experience, [Steve] is taking the lid off a number of previously undocumented techniques, many of which are especially relevant to the model-builder equipped with a 3D printer in the workshop.
As he continues his video log, [Steve] takes you through each detail, evaluating the quality of both his tools and techniques. How does a Makerbot, a Formlabs, and a Shapeways print stand up against being used in the target application? [Steve] evaluates a number of his turbine prints with a rigorous variable-controlled test setup.
How can we predict the plane’s center-of-gravity before committing to a physical design? [Steve] discusses related design decisions with an in-depth exploration of his CAD design, modeled down to the battery-pack wires. Though he’s not entirely finished, [Steve’s] work serves as a great chance to “dive into the mind of the engineer,” a rare opportunity when we usually discover a project after it’s been sealed from the outside.
3D printing functional parts with hobbyist-grade printers is still a rare sight, though we’ve seen a few pleasant and surprisingly practical components. With some tips from [Steve], we may complete this video journey with a few techniques that bump us out of the “novelty” realm and into a space where we too can start reliably printing functional parts. We’re looking forward to seeing the maiden voyage.
A student team has successfully designed, built, and flown a 3D printed RC plane using only $16 of plastic with a consumer-grade 3D printer (Makerbot), plus the necessary electronics and motor.
The folks over at the Wright Brothers Institute (WBI) have a great program called the AFRL Discovery Lab which brings teams of students, businesses, researchers, and government together to work on a specific challenge or opportunity.
One of the programs this year was the Disposable Miniature Air Vehicle, or DMAV for short. The student interns [Nathan, Ben, and Brian] spent the first 5 weeks at Tec^Edge designing the plane. The team went through 5 revisions before they settled on a design they believed could fly. The final plane weighed 1.5 pounds, and on its first flight… plummeted into the ground. Good thing they printed a second copy! After some more practice [Stephen] got the hang of it and was able to fly and land the plane successfully.
According to the WBI, this is the first functional aircraft that has been fully 3D printed (sans electronics) using FDM technology, and the first low wing 3D printed plane to be flown. Hate to burst their bubble, but 3D printed quadcopters have been around for quite a while!