3D printing is great for many things and for other things, the classic CNC mill is boss.Read More
Our tail design is not conventional, and requires a bit of care to ensure that it is aerodynamically and structurally sound. We decided to use 3D-printed parts to make the horizontal-fuselage and horizontal-vertical junctions. Here's our progress today.
…49 days later…
No, no, I haven't forgotten about you. I've just been laser focused on finishing construction and this shot at left is the result! However, it's all about the journey and I plan to leave out no details. Let's get caught up.
But, I digress. Let me first catch you up on what's happened since I began this post for the horizontal stabilizer.
You may have read my muse on the pros and cons, of 3D printing. The horizontal mounting (the plastic red and blue bit) is an example of a great 3D print application. The goal was to create a "bracket" to attach the horizontal, via to two carbon-fiber rods, to the fan structure. This does the job excellently, and allows the use of screws to make the tail removable for fitting the prototype into a car.
Similar to the wing, the horizontal was closed using thin balsa wood sheets.
I know what you're thinking. Why is there a 6mm carbon-fiber rod and servo wire protruding from the horizontal tip end?
What's that? You weren't thinking this? Well, in any case I think you'll find the post on our vertical stabilizers interesting!
The wing build certainly was challenging, but it was also fun. I'd like to share some of the journey with you. The wing sizing and planform shape came from Jon's airplane design inverse-calculator that he developed during his PhD research at DLR in Germany (more about that later). I picked out an airfoil shape with suitable moment and stall characteristics. After a bit of CAD work, I had ribs to laser-cut.
Assembly was straightforward and I made life easier by assembly everything in a foam "jig" (as we would say at Boeing).
Next came the skin and then ailerons. It's amazing how much balsa wood can bend after soaking in a tank for 3 hours (no fish were harmed during the build).
Last step before final skinning was to install the ailerons and make sure they work. Since the servo would be inaccessible inside the wing, once it's closed, I was careful to measure and test repeatedly.
Finally, after double- and triple-checking that everything worked, the remaining skin was added and the wing closed. The very last step before final airplane assembly will be to do a coat of epoxy to seal and give the wing a smooth finish!
Boom! The skin is completed. Servos are buried, and connected to working ailerons. All ribs and spars, except for the carbon-fiber rod main spar were laser cut from birch plywood and balsa.
Our prototype is being built in Livermore's IGATE workspace. We have been using the 3d printer their to create the belly fairing and propulsion structure for our first small scale prototype! We did have some issues today with the printer---all plastics are not made equal. But, nevertheless we have developed a work around and are continuing are 3d-printed part manufacturing. Thanks Jim for your help in getting our jobs working!!
Adrian finished the major wing assembly for our first prototype today. They are now curing: Adrian developed a rib-skin structure made out of balsa supported by carbon fiber fore and aft spars... The ribs were laser cut using I-GATE's state of the art laser-cutter. Next step is to add the aft-skin sections and then snap to main body---I think he deserves a lean black-belt don't you think??