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Can control surfaces for slow aircraft be 3D printed or even just printed as a core and then wrapped in fibreglass or carbon fibre?

I understand that 3D printing of wings, etc. is pretty common in the RC Aircraft world.

What about for slow flying aircraft such as Ultralights, etc.

In Rutan's book, "Moldless Composite Sandwich Aircraft Construction", Rutan strictly notes that only certain foams can be used as a core for structural components. Other foams are just for shaping of non-structural components such as interior panels, etc.

I assume there are certain engineering/material properties of the structural components that need to be met such as flexibility, no delamination, no structural degradation, high number of loading cycles, etc.

The question is, do any 3D printed materials meet these engineering/material properties.

Any help would be appreciated.

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  • $\begingroup$ If this is asking particularly about 3D printing a core, not other things, please emphasize that to guide answerers. (A Nomex-like honeycomb might be light and stiff enough, but I'm not sure about other properties.) $\endgroup$ Apr 1 at 16:00
  • $\begingroup$ "I understand that 3D printing of wings, etc. is pretty common in the RC Aircraft world". Can you cite even one example? $\endgroup$
    – Eric S
    Apr 2 at 14:04
  • $\begingroup$ @EricS There is special foaming filament available that is used for printing complete model aircraft. $\endgroup$
    – 0scar
    Apr 5 at 6:38
  • $\begingroup$ @0scar That’s new to me and very interesting. Thanks. $\endgroup$
    – Eric S
    Apr 5 at 15:45
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There are plenty of 3D printing methods available now with FDM being the most common. In my experience as small fixed wing UAV designer, all the 3D printing processes that are financially viable always under perform in comparison to alternatives. I can tell you the main issues I have encountered leaving the printing defects out:

  1. additive manufacturing doesn't lend itself well to mass production.
  2. It is too heavy for a core material.
  3. melts under heat, Fire hazard and safety issues.
  4. FDM prints are susceptible to fatigue especially when stress is transverse to the layers
  5. for commercial use , the end customer doesn't like 3d printed parts on his aircraft. simple as that
  6. machined metal parts are always stronger and cheaper than metal 3D printed parts.

However, it has some major benefits but mostly as a prototyping method. You can test the fits and physical size rather cheaply. I use it sometimes as a mold pattern for small parts. Also, 3D printing wings is not as common as you would think in RC world.

TLDR; with current technology, 3D printing is not suitable for stress critical components.

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    $\begingroup$ "does lend itself well to mass production well." did you mean doesn't? $\endgroup$ Apr 1 at 16:15
  • $\begingroup$ @HiddenWindshield edited $\endgroup$
    – Mridul
    Apr 1 at 20:40
  • $\begingroup$ "machined metal parts are always stronger and cheaper than metal 3d printed parts." Always is too strong a word. For very complex shapes such as some turbine blades 3D printing is both cheaper and better than machined. Also you can 3d print shapes that are unable to be machined. $\endgroup$
    – Eric S
    Apr 2 at 14:02
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    $\begingroup$ @EricS Metal 3d printing a turbine blade would be a poor design decision. Special casting methods with complex cores and gating are normally used to achieve the desired temperature resistance and strength. For compressor blades, forging is generally used. 3d printing metals is fairly expensive and will mostly be used by commercial aviation for non structural parts like a pump casing, because aircrafts maybe far from maintenance airport and time is more critical than money. Nevertheless, always is indeed a strong word $\endgroup$
    – Mridul
    Apr 2 at 20:41
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    $\begingroup$ @jamesqf You don’t have to convince me, it’s Mridul that is a skeptic. Relativity Space is 3D printing rocket engines. $\endgroup$
    – Eric S
    Apr 4 at 1:32
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I've seen several aircraft (at least the FAA would deem them to be such, even if "unmanned") that are entirely 3-d printed, so it seems that the answer to your question "Can control surfaces for slow aircraft be 3D printed?" must be "yes".

Related:

(Q) Why don't they build airplanes from 3D printer plastic?

(A) Why are geodesic airframes no longer produced?

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In these days, there is a range of printing materials available, so likely most of parts that are not too big could be 3D printed. Likely not from PLA that is for parts that do not require strength or heat resistance. But say glass filled nylon or polycarbonate are suitable for hard working mechanical parts, and ultem is heat resistant and flame retardant. It is also possible to 3D print from steel or even titanium, but for any larger part this would be very expensive. You can look say here for overview of the available methods. Sizes are currently the biggest problem, the most that majority of services could 3d print are only large enough for a drone.

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