FT Explorer in flight

3D Printed FT Explorer

I designed and 3D printed an RC plane!

Background

I started working on my FT Explorer design back in December 2017. I was at FliteTest HQ and I saw one of the 3DLabPrint planes on the wall. If you haven’t had the chance to see one in person let me assure you that they’re just as impressive from a foot away as they are on video. I asked if they would be interested in having any of their designs converted to a 3D model and 5ish months later here we are!

I chose the FT Explorer because it has a fairly simple structure and a good removable wing design. It’s also a pusher configuration which is great for beginner pilots such as myself.

Design

I contacted FliteTest and they sent me the CAD files they use to cut the foamboard out for their kits. FliteTest already posts all of their designs for free to download but they are PDFs. PDFs are great for traditional printing and cutting out on foamboard but aren’t great for 3D modeling. Thankfully I got my hands on the .dxf files which import great as sketches into Fusion360.

Don’t get me wrong, there was still quite a bit of work to be done on the files. Fusion was able to import them as sketches but the majority of shapes weren’t closed and couldn’t be extruded. As it turns out the CAD files have a lot of gaps in them to allow the parts to stay loosely attached to the excess foamboard so they don’t all fall out after cutting. This is great for laser cutting, but not for me. Thankfully Fusion360 has a ton of great features for modifying sketches and completing open shapes. The extend and trim sketch functions were especially useful. After quite a few different attempts I was able to modify the files to allow extrusion of solid shapes from the drawings.

At this point I went through a blur of undocumented testing, printing and modeling. I really wish I’d taken pictures of this process but I definitely didn’t. I was just too excited and just kept working. Next time I’ll do better, I promise.

I do however have some old versions of the design. I went through 2 complete restarts for a total of 3 main design files. Even though Fusion records a history of all functions there are just sometimes when it’s better to start over.

 

Printing

I used a combination of a few PLA brands for printing my FT Explorer. I’d planned on using Matterhackers‘ Build Series PLA (which is by far my favorite filament right now) for the entire build but after my printer broke I had to Frankenstein together parts of an early prototype. The brands in the prototype were WYZworks and 3D Solutech both from Amazon. I’ve been using WYZworks for a while and it’s a really great value with great print quality but with how demanding some parts of the plane were it struggled a bit. The 3D Solutech Natural Clear filament performed great as well and I definitely enjoyed the skeletal look it gave the design but for the “final” product I wanted an opaque model. Plus I really like the orange/light blue/white color scheme.

Updates

If you’ve already watched the FliteTest video you know that I need to make some changes. If you haven’t watched it just trust me, I need to make some changes. (also please do watch the video, it’s pretty entertaining)

Wing Reinforcement

First step was to reinforce the wing. I’ve since added a cavity that runs through the the wing which will allow a 1/8th inch dowel to be inserted. I chose that diameter since it’s what I had on hand, I’ll look into other spars later. Ultimately I plan to use carbon rod but I don’t have any. This should aid in construction as well because the spar rod will help keep things lined up during gluing. I had some issues with the sparless wing wanting to shift until the glue dried. I tried to use tape to keep it tight for the setting period which worked ok. In the video you can see tape on the one side because despite my efforts one of the joints shifted.

Weight

I also need to lighten the whole craft. This will be a little more difficult without a full redesign but definitely doable. I printed the white and orange parts of the fuselage with 2 perimeter shells as a test. These parts were very rigid but compared to their 1 perimeter counterparts they were noticeably heavier. I still plan to print the section of the fuselage that the wing rubber bands to with 2-3 perimeters just to make sure that the pegs don’t snap off but will likely do the rest with 1 perimeter.

Center of Gravity

As evidenced by the GoPro boom it’s pretty clear that the CG needs to move forward. I looked back through the model and realized I’d actually doubled the thickness of the tail fins to 10mm. Foamboard is about 5mm thick which is what I based the model off of. I’ve since gone back and trimmed them down to 5mm. I’m also experimenting with a tapered tail but that has structural implications that I haven’t explored yet. Hopefully a combination of these fixes will keep the CG where it needs to be. I’m glad though that we had to use the boom in the video because it got some great footage.

Motor Mount

I have a plan to design a mount with interchangeable motor plates. This is an improvement over using an open cross design to accommodate multiple motor hole spacings. This also allows the possibility for wooden or other solid mounting plates

The last of my current planned updates is a 3 channel wing and a 5 channel wing with slotted flaps, just for fun.

New Design (and color scheme)

I’ve come a long way since those earlier models and even from the first actual flight test, no pun intended (okay, maybe a little). Below is the current “release candidate” model. This does not include the tapered tail or variable motor mount. These are also the colors I plan to print the next one with.

The Future

My vision for my FT Explorer design is not to compete with 3DLabPrint but to supplement the market that they’ve created. 3DLabPrint’s designs are amazingly detailed and intricate but that can be intimidating for someone just getting into this side of the hobby. My goal is to produce models that are easy to print and assemble and that can introduce people to printed planes with lower risk.

Feel free to discuss and ask any questions below!

FT Explorer Videos

Here is the episode that FliteTest shot!

Below are the Instagram videos that they shot as well.

Leave a Reply

Your email address will not be published. Required fields are marked *