EDIT: Bonus FPV tail cam footage with a crash at the end!
For this build I am using a setup similar to how Bixler built his in the original video. I bought my glider from Hobby Lobby for around $6.50 with a 40% off coupon. I highly recommend going to Hobby Lobby and looking on their website for a coupon. Parts to complete this build are as follows:
- 1 Sheet of DTFB (depron or other foam materials will most likely work fine) - $1
- 1 Foam Glider (Look for the Sky Raider or Raptor 4ft wingspan version) - $6.60 with 40% off coupon
- 2 EMax RS1106 4500kv motors - $26 on FT
- Necelles (either hand cut from plywood or 3D printed using THIS FILE) - $5
- 2 12A EMax BLHeli ESCs - $19.50 on FT
- 2 EMax ES9051 4.6g Servos - $9.50
- 1 FlySky FS-ia6b Receiver - $17.50 on Amazon
- 2 EMax Avan Mini 3024 Props - $17 for 24 on Amazon (or use these from FT, they were sold out when I built this)
- 1 Hyperion 850mAh 3S Battery - $10.95 on FT
- Pushrods - $6 on FT
- Servo Stoppers - $5 on FT
- Mini Control Horns - $5 on FT
TOTAL COST = $126.05
That is if you buy everything new. Almost everything I used was salvaged from other builds except the motors, so I spent about $35 on this. Now that all that is out of the way, lets get building!
Start by cutting out your elevons from some DTFB. These are super simple to make and can be modifed to look however you'd like. Here is a simple template for cutting out some elevons.
After cutting out your two elevons, apply some packing tape to the underside of both. Just do the bottom for now so your hinge tape will stick to the paper and not the tape. Trim the tape so that is is flush with the edges of the elevons. This is not necessary but will improve water resistance and longevity.
Now, cut a single bevel on the bottom of each elevon where they will butt up against the elevator. Proper orientation is so the outside edge of the elevon is straight with tail surface.
Now apply tape to the top of each elevon and trim it so it is flush with the edges.
Carefully butt each elevon up against the tail and apply the tape. Make sure you use a scrap piece of foam to smooth out any air bubbles.
Make sure that the elevons have free and smooth range of movement both up and down.
Next, apply 2 more layers of tape to reinforce the hinge. I used one piece favoring the tail, and another favoring the elevon.
Now your tail section is complete! Sit back and admire your handiwork. I think if I destroy this air frame, this tail section is going to be built in to a micro flying wing!
Let's move on to the wings. You will need a carpenters square for this step. Place the flat edge of the square on the inside edge of the wing where it braces against the fuselage. Measure out ~3.5" and make a few marks on the wing with a pencil. This will be where the inside edge of the nacelle will sit.
Hopefully your nacelles are already built. You can cut these out of plywood by hand, or download the STL file I made and have them 3D printed. I opted to print them as I have access to a printer at work and PLA is incredibly cheap. I printed these with 100% infill and CA glued them together and they are very strong.
Download the Nacelle/Firewall STL file HERE
Take your nacelles and place them on the wing, lining up the inside edge with the marks you made earlier. Do this step with the props attached to make sure you have clearance for them on the wing. Then, using a little force and a rocking motion, press the nacelles in to the wing to leave an indent.
I then took a razor blade and did a light score cut in to the foam following where my indents were. Then, using a blunt object like a dull pencil, scrape the foam out.
Give the nacelles a firm push in to the foam. You want them to sit flush with little to no pressure applied.
Take your hot glue gun and glue the nacelles down to your wing. I used a bead of glue around the perimeter and some extra on the bottom to make sure they are good and stuck. Notice how I have this nacelle positioned, with the prop just barely clearing the leading edge of the wing.
Repeat these steps on the other wing and you now have motors ready to go! Note that I installed 2mm bullet connectors on my motors so that I can remove my wings easily for transport. I also put little dots on the connectors with a gold sharpie so that I connect them properly each time.
Let's move to the rear of the plane again. Install the tail on to the fuselage and prepare your servos. In this picture I show the "X" servo horn, but I ended up using the longer 3 hole horn as these did not provide the throw I wanted.
Place your servo near the leading edge of the tail and glue it down just like you would on any FT scratch build.
Next, take a push rod and control horn and mock up where you are going to mount the horn. The push rod should be in a straight line with the horn, and the eyelet of the horn should be centered over your hinge.
Push the control horn down in to your elevon to make an indent of where you want it to sit. Then take a razor blade and cut a score in the center of your indent. Push the control horn down in to the score cut to verify it is sitting flush.
Glue down your control horn, trim your push rod and set the center on the elevon with the servo stopper. I made my elevons level with the tail surface and it flew perfect with no trimming.
Now repeat these steps on the other side. You now have elevon control! For reference, my control horns are mounted ~3/4" from the inside edge of the elevon.
Now all that is left in the final details to make everything work. Here is the receiver I am using, a FlySky FS-iA6B. I flipped it upside down and dug out foam from the fuselage so that the bump sits down in to the foam, but not so deep that I cannot remove or install servo wires. I then glued it in to place. I also used a small flat head screwdriver to make a channel that the antenna wire can sit in, then glued the antennas down in the proper orientation.
If you are using ESCs with a built in BEC, make sure tocut the power wire from one of the 2.
I then used the screwdriver method to make channels for the servo wires, and routed and connected them to the receiver. You can also see the longer control horns I used in the second picture. Note that the servos are not connected to the proper ports in this picture. For my FlySky setup, CH1 is L Elevon, CH2 is R Elevon, CH3 is L ESC, CH4 is unused and CH5 is R ESC. I setup my radio for elevon control and used 3 mix channels to setup the R ESC and differential thrust.
Mount the wings to the fuselage and mock up where you want your ESCs. Once you are happy with where they are, use a small amount of glue and stick them down. Notice that I spliced the power wires of both together in to a single XT30 connector. Also now is a good time to put down a strip of velcro for your battery to attach to.
Place your battery on the underside of the plane and move it around to find the proper CG. This build was perfectly balanced without the battery installed, so the best location for me was centered on the CG. I made some marks with a sharpie to remember the proper battery placement. I also ended up sticking a battery tester down to the velcro so I knew when to bring her in for a landing.
Now it's time to bind your transmitter and do the final setup! I am using a elevon mix in my radio, and a 75% differential thrust mix for yaw. My low rates have everything turned down to 50% with 30% expo, and sport rate are 100%. On low rates the plane fly very docile and is an absolue beginners dream! On high rates you can do awesome bank and yanks, flips and flat spins on command!!
Time to go throw it in the air and have a blast! This is now my favorite plane in my arsenal. I get about 6-8min of flight time on a 850mAh 3S depending on how I am flying it. It will cruise with as little as 20% throttle. I would recommend hand launching it with the throttle set to about 50% and give it a good toss.
Now, what are you waiting for? Go build one of these for yourself!
I hope you enjoyed my first article! I have learned so much from this site that it was time I gave something back :)
Link to the original video that inspired this build: