How to Design and Print 3d Printed RC Aircrafts

About: Instructor by trade at MMI. Hobbies include all air RC, 3d printing, and I love 3d modeling

I would like to share my attempt at 3d designing and printing my own rc airplane. At first I purchased some of 3Dlabprint (www.3dlabprint.com) rc airplanes to test them out. After trying them I started on my own. I will tell you I have never stick built an rc plane so I did not have the background to figure out things like wing profiles.

I started off by figuring out what airplane I would like to do. There were so many that I liked that it made the decision tough. I went from SR71 blackbirds all the way thru F-14 tomcats, but in the end I started with a simpler design. I choose a simple delta wing (Mirage 2000), with the thought that it would be would be the best bet for the first attempt. Spoiler alert, after many months of designing in a 3d cad program and printing it, I did get the chance to maiden it, but the first attempt was unsuccessful and the second attempt the actual flight was very (very) short. There are videos at the end, but I cut it off as soon as it left the ground as the ground came back just as fast as it took off. Lesson learned, recalculate CoG (center of gravity) before you just give it a try. More on that later!

This instructable is written as if the reader has experience in building RC airplanes, so I will not be going over how to set up the radio or setting throws. This is an intro on how to start 3d modeling and printing your own RC aircraft. The reading is brief, but there are a lot of pictures.

I have included a list of the materials I used and links for them.

Supplies:

2) rolls of PLA filament- https://coexllc.com/products/3d-filaments/pla-filament/pla/

3) 6mm carbon fiber tubes 1 meter long- https://alofthobbies.com/carbon-fiber-tubes.html

1) 70mm FMS EDF and ESC- http://www.fmsmodel.com/fms-70mm-ducted-fan-v2-12-blades-with-inrunner-motor-2860-kv1850-for-6s and http://www.fmsmodel.com/predator-esc-85a-3788

3) landing gear from Hobby king-https://hobbyking.com/en_us/alloy-oleo-strut-set-with-anti-rotation-link-and-wheels-3mm-pin-trike.html

3) hobby king thin wing servos-https://hobbyking.com/en_us/corona-ds-239mg-digital-slim-wing-servo-metal-gear-4-6kg-0-15sec-22g.html

1) Receiver, I use a Futaba radio, but use whatever radio and receiver you have as long as it has atleast 4 channels

Servo extensions- https://hobbyking.com/en_us/servo-extension-lead-42cm-5pcs-bag.html

Music wire for the controls-https://hobbyking.com/en_us/1-meter-music-wire-1mm.html

Control hinges-https://hobbyking.com/en_us/ca-hinge-l25-w20-h0-3-10pcs.html

and few various screws for the landing gear mounts.

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Step 1: Choose Your Model

Choose a model that you like. There are plenty of resources on the web to aid in this. Also make sure that it is not the most complicated design as that will discourage someone that is new to this. Once you have chosen the model you want to use then it’s a matter of deciding to use an existing 3D model and editing it or start from the bottom up. If you decide that you would rather start with a base 3d model and edit it, there are a lot of websites that you can download models from. Some free and some cost.

Some examples of websites would be:

www.grabcad.com

www.thingiverse.com

www.cgtrader.com

Please keep in mind that not all models may be used. Some have special licenses that allow or deny you to edit and use the models. Some you may have to attribute the original maker of the model, and some may be a royalty free license allowing you to edit and resell if it is not the same format as the original.

On the other hand if you would like to start from the ground up, you will need to find 3 good profiles of the plane. One front, one side, and one top profile that are from the same source, here is a website that I use for this: https://www.the-blueprints.com/. Also you will need a lot of pictures of the plane from various angles to be able to model the finer details.

Step 2: Software

Choose the 3d modeling program you would like to use or you are familiar with. If you have not used any modeling software in the past then you will have to spend some time getting familiar with how the software works. There is a ton of software out there to use. Again, some free, some not, and some unbelievable expensive.

Some software to look at:

https://www.blender.org/

www.sketchup.com

https://www.freecadweb.org/

www.autodesktop.com

https://www.solidworks.com/

I have found that even some of the expensive software can be bought on a time license cheaper than normal. I myself like Solidworks but it is very expensive and it is more in-depth than what is needed to model this project. I chose solidworks because I was able to buy it at a huge discount. If you are Military, a current student, or a teacher you can pick up solidworks for $150 per year as compared to $14000 for the suite. Keep in mind this is my preference, if I would have started out with free software I would have stuck with that software. I believe autocad suite has a very similar deal, that doesn’t cost anything.

Once you have chosen your software, do not get frustrated if you can’t use it well. There are plenty of resources on the web that have tutorials to help you learn it. Sometimes, Youtube is a wonderful place to start for this.

On this model I decided to use an existing model and modify it. So I will go thru the step of this method for now. I was able to find a mirage 2000 that someone else (username Diymik from thingiverse) originally modeled for a very small rc plane: https://www.thingiverse.com/thing:2204596 . I decided to print that out first and see how the model was. It did take some time but it also gave me some insight as to what had to be changed to make it work for my project. If you are heading this way understand that not all 3d models can be edited using any 3d modeling software. You may have to covert the file to something that your software can work with. The most universal format I have found is .iges or .igs, most software can handle this.

Step 3:

At this point I was ready to try my hand at editing the model for my use. Something I figured out thru trial and error. Patience grasshopper, always map everything out ahead of time, be ready to make mistakes, save your work often and use a logical naming convention.

All of these steps are just about the editing the file. Although I will not be hitting every single step it took to model this I will hit the main points, otherwise I might end up with a 100GB instructable. I will be using Solidworks so your software may have a different way of accomplishing the same thing. I had to import the file into the software, but the file that Diymik had would not import well as it was a stl file and solidworks doesn’t like large stl files. I had to locate the original file that Diymik used from www.grabcad.com. Lucky enough it was in the correct file format for me to import to Solidworks.

While importing the file I had to set it up to import the .igs into surfaces without knitting. Then delete all parts on ½ of the model. I start by trimming the surface on the mid plane. Then I have to manually trim the rest of that half, so I only have half of the model and it is hollow on the inside. SAVE in your file format at this time.

Step 4:

Start measuring to make sure it fits your electronics and scale if need be. For mine the original file was way too big and I scaled it down 50% so I could fit a 70MM edf in the fuselage. As seen in the pictures the original fuse was about 216mm and then it shows the comparison of about 106mm. This left enough room for me to build the edf mount.

Step 5:

At this point I needed to start thinking about internal structures, access panels to get into the plane for electronics, edf, and battery, and how to make the wings so they were detachable. I decided to make the wing have a small extruded end coming out of it and a .4mm larger cutout into the fuse. Once that was finished then I made the bolt holes that screw the wing to the fuselage. Then made internal tubes so I could use carbon fiber tubes as spars for the wings thru the fuselage. After I had the outer skin knitted, I started working on the internal structures. On mine I went with solid internal structures and kept the skin a surface model. The internals are offset .7mm from the skin so when it prints the internal structures would touch the fuselage skin and become one part. I also incorporated a small carbon tube all the way from the back to front of the fuse.

Step 6:

Once the fuselage was set with the internal structures I made a mirror of the left side and knitted to the sides together to give me a complete fuselage. Here you can see the outer surface fuselage and then just the internal solid structures. A word of caution here will save you a lot of time not remodeling what you have already done. When I had the wing extrusion and fuselage cutout done, I printed just those sections to see how well they mated together. If you finish the complete model and then test print, you may have wasted a week or 2 having to go back and change everything you just did. Print small test pieces on the way to avoid issues later on.

Step 7:

I went on to finish the wings, such as servo cut out and elevons (a mix or elevator and ailerons). Then finish the internal structures of the wings.

Step 8:

After I had the right wing done I just mirrored it for the left wing. I was now ready to finish up on the top hatch and the cheater hatch on the bottom. The cheater hatch is just a removable hatch to install the edf (electric ducted fan) but also helps supply enough air to the edf as the ducts in the front of the fuselage could not breath enough for the edf to operate efficiently. I made the cheater hatch so the carbon fiber tube runs from the rear to the front of the fuselage so I can pull it out and remove the hatch. The top hatch or cockpit is held on with a latch in the front and magnets in the rear. The key to the hatches are to finish the internals on the fuselage then cutout the hatches, that way they match the fuselage supporting structures.

Step 9:

I was nearing the end and realized I did not have any kind of landing gear, so I went back and incorporated some blocks and cutouts for the landing gear and used the carbon tube to run thru the blocks to hold them to the plane. I also had to make a servo mount for steering the front gear.

Step 10:

I was getting close to finishing it but still had to put on a few details such as the tail feathers and the filler tube for the front.

Step 11:

Time to cut the fuselage up into smaller pieces as the whole thing can not fit in the printer at once. Cut the fuselage and wing up into sections that could be easily printed.

Step 12:

At this point I started to print it. Printing took well over 60 hours as I printed 1 piece at a time. I printed this way incase 1 piece messed up I didn’t waste all the pieces. This was a very tough project for me to do but I enjoyed every minute of it. Even the horrible crash on the maiden (which I am sure you will love) and the very short flight on the remaiden. Here are some pictures of the printed plane. The yellow fuselage was Diymik's for comparison to my version (blue one).

Step 13:

Step 14:

Installing the electronics. Install the edf from the bottom thru the hatch, there are 2 holes for screwing the edf to the mount. Then route the wires thru the wire channel in the top of the fuselage. Install servos and route wiring to receiver. Servos are held in with the little 3d printed straps and small screws.

And just a quick look at how the landing gear was installed. Landing gear pin is mounted thru the printed block and held in with a grub screw then the block is placed into the fuselage and the carbon rod runs thru it to secure it.

Step 15:

Last you will need to find a program that can help with determining CoG (Center of Gravity). This is the one I used:

https://fwcg.3dzone.dk/

Step 16: Do or Die!

Here is the first maiden, it was like setting a land speed record……. Too nose heavy but not too much damage for the speed that it was moving and being 3d printed, and the remaiden still a little nose heavy, but atleast it left the ground for a few seconds with a little help. I am in the process of reprinting with a few small changes and will do another test flight once it cools off. Here in overly sunny and hellish heat Phoenix the pla planes will warp if they sit in the heat for more than a couple minutes.

Step 17:

Thanks for looking at my instructable, and hope you enjoyed it. If you did please vote for this in the make it fly challange. I would like to thank all the others that are pioneering this method that enticed me to try it. Just to name a few of them:

DirtyDee and his great airliner: https://www.rcgroups.com/forums/showthread.php?311...

Lynxman for his L39: https://www.rcgroups.com/forums/showthread.php?305...

Carletto73 for his Gasb planes: https://www.rcgroups.com/forums/showthread.php?330...

If your interested in trying to print this I have included the files. Most parts are printed 2 perimeter for 2mm up then 1 perimenter for the rest. Some parts may need 2 bottom and 2 top layers if they have the tubes going thru them, but then you need 3 processes so you can have process 1 no top or bottom but 2 perimeter end at 2mm, process 2 start at 2mm and add in top and bottom layers at 1 perimeter up to just before the top of the print, then process 3 back to not top or bottom and stay at 1 perimeter for the rest of it.

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