Introduction
After watching the FliteTest episode about the 3D printed P-38 lightning, I couldn't help but think, are 3D printed planes the future? or just temporarily really cool? So being an undergraduate in aerospace enginnering myself (will be graduating this year), my instinct was to design an aircraft from scratch.
Wing development
A few days went by of messing around with a CAD software and a 3D printer slicer to produce a basic, but lightweight, wing structure. I documented my experimentation in the following video.
The summary of the video was that I didn't recommend 3D printing all your future RC planes due to print times, weight and structural reasons. After a week or so, this video got a lot of attention on youtube and I'm not sure if you can call it peer pressure, but I felt like I had to prove myself wrong!
Plane design
I first began designing a conventional aircraft with a moderate aspect ratio, non swept wing. To save as much weight as possible, the plan was to use a carbon tube as the rear part of the fuselage (between the rear of the main wing and the rear stabiliser). BUT, this wouldn't make it a 'fully 3D printed plane'. So I ended up going with a flying wing configuration.
Due to the lack of optional CG placement in a flying wing, the design incorporated a fuselage that was mounted below the wing. This would allow the battery to be mounted out the front of the wing, allowing a light weight battery to be used while still acheiving the correct CG. The motor mount was also positioned on the front of the fuselage to bring the CG forward.
Print and build process
The plane was printed on a kossel mini 3D printer with a 0.4mm nozzle. Printed with a 0.6mm wall thickness and 0.2mm layer height. I used PLA as this was such a complex print (PLA is the easiest material to print as far as I know). Temperature of the nozzle was 215 degrees celcius and printed very slow (30-40mm/s) to get the best layer strength.
Will it fly?
The whole build and test flight process was documented in the following video, enjoy!
Spoiler alert below!
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Specification
AUW - 730g
Battery - 4s 1000mah
Motor - Cobra 2204 1960kv
Prop - DAL6045
ESC - UBAD 20A
Servos - Hobbyking HXT900
Summary
Aside from the winglet and airfoil design, the aircraft flew suprisingly well! It made clear to me that there are actually are some advantages to 3D printed planes, but not in the way that I had expected. The plane would most likely be lighter if made from foam or balsa and it probably be more durable. BUT 3D printed wings have the advantage of being designed in a CAD software and tested in a CFD (Computation Fluid Dynamic) software, which can allow for more complex design of airfoils which may be limited by other building technique. Fully 3D printed planes will most likely be heavier than foam/balsa, but if designed to accept a covering film, I reckon the weight can be drastically reduced and a complex airfoil design might make up for the added weight... who knows... all I can say is that this isn't going to be the last 3D printed plane I produce!
One final note, I haven't made the stl files public yet as I am working on a version 2, so it would be great if you could subscribe to my youtube channel if you are interested! Thanks
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