• Jon

How to 3D Print an Aeroplane - Day 12 - Elevator controls

Today is time to add in some elevator controls. Although it's always worth leaving this kind of thing until the majority of the modelling is complete, so that you know what you have to work with, its worth having it in the back of your mind during the earlier stages of the design. I have competed a few designs where this became a huge headache at the end.



Similarly to the blog post on sectioning the


tail boom, the screencast for this is only about 15 minutes. Don't believe it! At least an hour was spent thinking through various different configurations.


I toyed with having the servo mounted in the fin. I couldn't quite get enough room and besides, I usually prefer to keep things near the centre of mass. I have gone with a mounting in the left wing. The way the wing is sectioned means that this cutout will be at the top of the wing when it is printed, so no supports required.




TTFAM (*Top Tip For Aero Modellers): You can slice this part, or position it in Cura so that you print just the top section (see below) to check the servo cutout for a good fit, before printing the whole thing. Especially useful for parts with day long print times...




Next up is to model a control rod. In practice this will be made from piano wire but by modelling it we can check, and adjust its routing through the model and use it to make the cutouts as required. I prefer to make the control rod a new body this way rather than a cut, as I find it easier to move at a later stage if needed. Depending on the gauge piano wire you are using, you can get away with having some bend in the path it takes, obviously too much and you'll end up with a lot of friction, hampering the servo.


So. we have a control rod modelled but before cutting out the path in the boom we need to mirror the left side empennage to replace the right asa we have done all the sectioning. If we mirror it later we will have the cutout for elevator controls which we don't need. I also slightly adjusted the horizontal stab and elevator so I am going to mirror them too. Instead of mirroring the left side wing have have just matched the change in sectioning as, again, I don't need the cutout for an elevator servo.


After cutting each tail boom section, locating the cutout parts and sending them to the trash, we need to model an elevator linkage. With these linkages I sometimes make them integral to the part so it prints as once piece, we will do this with the ailerons, but for the elevator I'm just going to make a stand alone part that can be glued onto the elevator during assembly.




 

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