Ever wondered, how reliable are fully 3D printed planes in real? Recently I decided to decomission my Zivko Edge I’ve been flying for more than a year and I’d like to tell you what I have found flying it every suitable day of the year. I maidened this particular Edge in May 2017 and since then it survived many flights. But nothing takes forever and I crashed it once more due to turning autolevel feature with wrong set attitude too low.

Although the damage wasn’t unrepairable, I decided not to fix it this time. I wanted a new paintjob and this Edge was not so nice as it was in its first days. But it inspired me to write this article.

The very last “flight” of this plane caught on the video…

 

Color really matters…

The wise choice of filament and paintjob color determines how your plane holds up in direct sunlight. Since PLA gets soft around 60°C, dark colors heat up in the sun very quickly. You can see some warping on the black canopy and silver parts of the wing and fuselage, that is however not an issue on the orange parts. Sometimes it was almost impossible to keep touch on the black canopy, while the orange parts were pretty cold in the same moment.

If you want dark colours on your plane, keep it in shade while not flying it. Also you can paint black stripes or patterns on the bottom part to determine the plane orientation easily.

Repairs

With a plane fast like this you really need to learn, how to properly bring it down. You can try as hard as you can, but sometimes the bad thing happens and you return from the field with plane in more than one part. You can always extract the electronics off the plane and reprint. In three days you can be back in air, but it’s not always necessary to print the whole plane again.

I tried many procedures including various hot tools to separate broken parts from the rest. The best tool I found is the metal cutting disc on rotary tool like Dremel. Roughly cut off the broken part along the glue line and then carefully clean the surface, so you can glue the new printed part.

Since the glue joints are probably the strongest parts of the plane, reprinting is not always necessary at all. Many times I simply glued the broken parts together in the field.

Sometimes when small piece of plastic was missing, I used a masking tape impregnated with CA glue as a filler

Reinforcement

In the past I’d suggest reinforcing the F2 part using 2 perimeter settings where the landing gear is conected to the fuselage, but the Edge got recently updated with new detachable landing gear. For fields with grass surface I’d suggest cutting off the wheel covers and replacing the wheels with some larger ones. The edge is landing quite in high speed and we don’t want the gear catch on any pothole or lump of grass. Printing the LG with more perimeters is wise, same as melting in two 1mm wires into each leg for reinforcement. I used standard PLA as for the rest of the plane.

Piece of EPP foam in the F5 part of the fuselage weights nothing and improves the stiffness of the fuselage right where many people tends to grab the plane. Not necessary for flight, but wise for handling.

Do I need a carbon spar in the wing?

Edge is a fast and sporty acrobatic plane, capable of tight maneuvers. Many people were complaining about absence of carbon spar in the wing for extra safety. But PLA is, unlike foam or balsa, very stiff and the wing has been designed with reinforcement spars inside the wing already. When printed and assembled according to the instructions, it easily survives all sticks to the side and the plane flies like on rails. The stiffness is comparable to the composite planes, so the answer to this question is: Not at all.

Conclusion

3D printed planes are not to replace other building methods, but offering another option to the hobby. If you have a 3D printer at home, the spare parts are easily available and won’t ruin your wallet. And if you dig the plane into the ground, you simply salvage the electronics and reprint again. Even balsa planes covered with dark foil has to be kept in shade, so the cover won’t wrinkle. And if you crash it, the repair is not so easy. Foamies on the opposite are way too flexible and doesn’t fly like these at all.

Petr Šťásek.