The Frankenplane: DIY Fully Modular RC Airplane

Are you a big fan of science and aviation looking for a new project? Well the Frankenplane is for you! This is no normal RC airplane though. It can be a fun park flier, a light motorglider, a test platform, or really anything you want it to be! This is all because it's all built off of an 8mm diameter carbon fiber tube with easily removable and modular power pod, wing, and tail components made of a combination of 3-D printing, laser cutting, and foamboard construction. This allows you to add or switch components as much as you like. The original design is made to be a motorglider with a 60 inch wingspan, but that's just what's in the original design. Components are mounted to the carbon tube using grub screws allowing for easy change of position, components, or anything else you'd like. It's all up to your imagination what can take to the sky. Test out new wingspans, airfoils, or drop systems without dealing with the hassle of cutting anything off or gluing anything onto your beautiful plane. You will need access to a 3d printer and laser cutter but if you don't have one don't worry. If you are in school many school's have 3D printers and laser cutters (I personally asked my school and they were happy to let me use them), but if not it is often just a case of finding a local maker-space that is willing to give you some help; there are lots of online recourse to help you out with that. Access to Fusion 360 is also recommended to be able to view the full design. I made this purely from part's I had already laying around in my house as well as in my schools engineering club but you may have to collect some things. I plan to use this airplane as a platform for testing different airfoils in the future and will add instruments and autopilot to the electronics bay. Many of the key components use Flite Test build techniques so if you have any other questions the Flite Test videos and forums are excellent places to find answers. Flite Test was a big part of what got me into flight so I'd like to thank them and their team a lot. They also have an excellent beginner series which I would highly reccomend and would be very helpful to any begginers attempting this build (https://www.youtube.com/watch?v=dOziFzntXq4&list=PL6IuSFWz4ktvupu_gxw1vn-sjBGOkJFHV)

I'm a sophomore at The Branson School and I would like to thank Christopher M. for helping me so much with this project and Mr. Wick for being so accommodating in my schools engineering club with this project.

Supplies

Here is a list of materials you will need. If you don't have any of the material's readily on hand I've linked my favorite version of that item so you can buy it.

carbon fiber tube (750mm long, 8mm OD, 6mm ID):

https://www.motionrc.com/products/benchcraft-8mm-x-6mm-id-hollow-carbon-fiber-tube-1-meter-bct5051-032?gclid=Cj0KCQjwgNanBhDUARIsAAeIcAuqzh1pEL4jKv8jTa-gt1l0W7mZz3jDaGTm8cZZoPSEXEjNVmbByQoaAuHjEALw_wcB

3 sheets of dollar store foamboard (at least 30 inch by 30 inch) flite test foamboard also works great if you have access to it

https://store.flitetest.com/flite-test-maker-foam-board-by-adams-20-pack/

A 3d printer and your favorite filament (I used a Prusa Mk 3 and some white PLA)

https://www.printedsolid.com/collections/jessie?gad=1&gclid=Cj0KCQjwgNanBhDUARIsAAeIcAvkXJobARTzzKcb1WtxVUUYoKFRxE4rZg1xBkPiFmcmi4zTfDaJSb8aAr5GEALw_wcB

M3 Brass heat set inserts ( mm long)

https://www.amazon.com/M2-M2-5-M3-M4-M5/dp/B0C2HGNYLX/ref=sr_1_5?crid=C8KJ8AA9J7T3&keywords=brass+heat+set+inserts&qid=1693882583&sprefix=brass+heat+set+inserts%2Caps%2C189&sr=8-5

M3 bolts

https://www.amazon.com/SUNXULIMI-Button-Socket-Stainless-Threaded/dp/B0C3MQ7QZC/ref=sr_1_3?crid=1YAH4TEIH0GYO&keywords=m3%2Bx%2B10%2Bmm%2Bbolt&qid=1693882668&sprefix=m3%2Bx%2B10%2Bmm%2Bbolt%2Caps%2C179&sr=8-3&th=1

A sheet of 1/8 in thick acrylic

https://www.amazon.com/Falken-Design-Acrylic-Plexiglass-Opaque/dp/B07NRC8N1X/ref=sr_1_2?crid=1WX3MA17JZLBQ&keywords=1%2F8th+inch+thick+acrylic&qid=1693882745&sprefix=1%2F8th+inch+thick+acrylic%2Caps%2C180&sr=8-2

Neoprene (or Nylon) washers (about 4mm ID 10mm OD, really just anything that works for an M3 bolt)

https://www.amazon.com/Sutemribor-Nylon-Washer-Assortment-Sizes/dp/B07KQVNQ95/ref=sr_1_1_sspa?crid=2M5LMO290ERLP&keywords=nylon+washers+3%2F8&qid=1693882874&sprefix=nylon+washers+3%2F8%2Caps%2C177&sr=8-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&psc=1

Your favorite RC airplane transmitter + reciever combo (I used a Spektrum radio and reciever that I already had)

https://www.amazon.com/Spektrum-Transmitter-AR410-Receiver-SPM1010/dp/B08CKY3D7H/ref=sr_1_1?crid=1F45S128BBGBA&keywords=spektrum+transmitter+receiver+combo&qid=1693883060&sprefix=spektrum+transmitter+reciever+combo+%2Caps%2C174&sr=8-1

Flite Test Power Pack A

https://store.flitetest.com/ft-power-pack-a-radial-v-2/

Push rod wire

https://store.flitetest.com/push-rods-8-pack-23/

mighty mini control horns

https://store.flitetest.com/ft-mighty-mini-control-horns-20pcs/

mighty mini power pod

https://store.flitetest.com/mighty-mini-firewalls-5-pack/

barbecue skewers

https://www.amazon.com/HOPELF-Natural-Skewers-BBQ%EF%BC%8CAppetiser%EF%BC%8CFruit%EF%BC%8CCocktail%EF%BC%8CKabob%EF%BC%8CChocolate-Fountain%EF%BC%8CGrilling%EF%BC%8CBarbecue%EF%BC%8CKitchen%EF%BC%8CCrafting/dp/B07MY7W5LJ/ref=sr_1_2_sspa?crid=2EIF65HJINXNF&keywords=barbeque+skewers&qid=1693883292&sprefix=barbeque+skewers%2Caps%2C192&sr=8-2-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&psc=1

Servo wire extensions

https://www.amazon.com/TecUnite-Extension-Connectors-Connection-Control/dp/B07C18BXDV/ref=sr_1_1_sspa?crid=CJIJA6TYNAKX&keywords=servo+wire+extensions&qid=1693883345&sprefix=servo+wire+extension%2Caps%2C183&sr=8-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&psc=1

A hot glue gun

https://store.flitetest.com/flite-test-80w-glue-gun/

A soldering iron (for the heat set inserts)

I would recommend borrowing a soldering iron from a friend or your local maker space but here's the one I used for this project (note: you don't need an iron this nice any soldering iron at all will work): https://www.amazon.com/Hakko-FX888D-23BY-Digital-Soldering-Station/dp/B00ANZRT4M/ref=sr_1_2?crid=1UCQ05G1LSBIR&keywords=hakko+soldering+iron&qid=1693883603&sprefix=hakko+sol%2Caps%2C191&sr=8-2&ufe=app_do%3Aamzn1.fos.f5122f16-c3e8-4386-bf32-63e904010ad0

A utility knife for cutting foamboard

https://www.amazon.com/AmazonBasics-Folding-Utility-Knife-Lightweight/dp/B07TBNH4ZT/ref=sr_1_1_ffob_sspa?crid=NX08D4MA78PJ&keywords=utility+knife&qid=1693883678&sprefix=utility+knife%2Caps%2C173&sr=8-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&psc=1

A measuring tape or yard stick (for measuring cuts)

You probably have some version of this but on the off-chance you don't: https://www.amazon.com/Westcott-Wooden-Yardstick-Lacquer-10425/dp/B0017DGZ1W/ref=sr_1_6?crid=22MZAE8DG1N8T&keywords=yard+stick&qid=1693883775&sprefix=yard+stick%2Caps%2C189&sr=8-6

3s 850mah LiPo battery

https://www.amazon.com/TATTU-850mAh-Battery-Multirotor-Quadcopter/dp/B074MG6YGS/ref=sr_1_1_sspa?crid=1HAY84RA0URHL&keywords=tattu+3s+lipo+battery&qid=1693883909&sprefix=tattu+%2Caps%2C184&sr=8-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&psc=1

Packing tape (duct tape works too)

https://www.amazon.com/Scotch-Heavy-Packaging-Inches-Clear/dp/B00RSB6I1E/ref=sr_1_5?crid=TM9RFM4SN5XA&keywords=packing+tape&qid=1693883945&sprefix=packing+tap%2Caps%2C174&sr=8-5

battery strap (or some tape and an open mindset)

https://www.amazon.com/iFlight-Rubberized-Non-Slip-Fastening-Quadcopter/dp/B07XL8NLLZ/ref=sr_1_1_sspa?crid=36WXMLA7D1NQW&keywords=drone+battery+strap&qid=1693883982&sprefix=drone+battery+strap+%2Caps%2C172&sr=8-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&psc=1

If I forgot anything please feel free to comment and let me know, I'm happy to help you and improve my instructable.

Step 1: Making a Wing - 1

Find your 30 inch long piece of foam board and make marks along one side at the measurements specified in the image. Remember, measure once, cut twice. Wait that's not right. ¯\_(ツ)_/¯

After you've done this make these marks into lines that run across all 30 inches of you foamboard and make score cuts along them. (this means cut through the top paper and some of the foam but not the the bottom foam)

Step 2: Making a Wing - 2

Now we have to make a spar to keep the wing rigid.

Follow the same directions as step one following the diagram to make your wing spar. When done, peel out the 5mm segments you cut and assemble it like in the diagram with hot glue.

Step 3: Making a Wing - 3

Place hot glue on the section of wing as shown in the diagram in step 2 and place the spar on that glue.

Step 4: Making a Wing - 4

Now do a test fit folding you sheet of foamboard over into a wing shape like the one shown in cad. It should take on a nice airfoil shape after cutting bevels in both sides of the score cut for the leading edge. When you feel ready place glue on the bottom of the spar and fold it over. Wait for it to cool and then place glue on the trailing edge of the wing. Now repeat all of the steps up until this step so you have two halves of a wing taking car to make sure they look exactly the same.

Step 5: Making a Wing - 5

Now put glue on the end of one of the wings and but up the two halves of the wing to eachother. This should glue the two halves of the wing together. While the glue is hot I like to wrap packing tape around this joint because it takes a lot of stress.

Step 6: Making a Wing - 6

Now take the wing mount printed part and melt in the two heat set inserts to their spots. Then glue this to the middle bottom of the wing taking care to make sure it is in fact perfectly perpendicular.

Step 7: Making a Wing - 7

Add ailerons by making little 35mm x 540mm foamboard rectangles and bevel one of the long sides on each. Then tape them with packing tape to the ends of the wings with the bevel towards the trailing edge. Now add servos as shown in the photo by cutting holes in the bottom of the wing and putting the servo's in them. Add servo wire extensions so you can route the servo's wires all the way out the middle of the wing and will in the future route it to the reciever.

Step 8: Tail Section - 1

Print out the empinage mount and add heat set inserts.

Step 9: Tail Section - 2

Cut out the vertical and horizontal stabilizers from foamboard as shown in cad. Score the lines for the control surfaces as seen in the sketches of the stabilizers of the cad model. They basically start at the back of the mount.

Step 10: Tail Section - 3

Glue the your foam board stabilizers to the printed mount as shown in cad. They should easily slot together. Once these are secured add a barbeque skewer or straw as shown in the images to the rear of the horizontal stabilizer so as to connect the two sides.

Step 11: Tail Section - 4

Now we have to add servos. Cut holes through the foam board pieces to put the servo's through and install control horns and wire as shown in the pictures. Make sure you have enough extension wire for your servos to reach the receiver.

Step 12: Main Fuselage - 1

Print the battery mount, bulkhead assembly, and front bumper. Add heat set inserts into their places on the parts (note: the front bumper does not have heat set inserts, screws tap directly into the plastic to create a point of failure in the event of a crash)

Step 13: Main Fuselage - 2

Take the sketch for the side walls and laser cut them from 1/8 in thick acrylic. If you're willing to get creative these pieces could likely be made of thin plywood as well by hand so long as you don't include the weight reduction triangles.

Step 14: Main Fuselage - 3

Now it's time to make your power pod. I just used a Flite Test mighty mini power pod which can be made by following this video: https://www.youtube.com/watch?v=axOnU5GKSJI

Once you're done, wire the esc to the reciver.

Step 15: Assembly - 1

Now it's time to mount all of your components to the carbon rod. Take your 750mm long carbon fiber tube and slide your battery mount and bulkhead assembly onto one end as seen in cad. Make sure the bulkhead assembly is right on the end of the tube and tighten the screws just enough so that there is enought friction that it can't freely move but not enough you crack or damage the carbon tube. Now is a good time to install and wire your reciever while you still have good access to the space.

Step 16: Assembly - 2

Now begin aligning holes on the nose walls and the bulkhead assembly and start adding screws. Now is when you will use your neoprene or nylon washers so as not to crack and scratch your acrylic. Add the front bumper while you do this as well.

Step 17: Assembly - 3

Attach the power pod by skewering it with two barbecue skewers and adding some glue to the skewers next to where they touch the acrylic. Take care to keep the thrust line parallel to the carbon rod. Route the battery wires to the battery mount and the pwm wires to the receiver.

Step 18: Assembly - 4

Now it's time to slide on the wing and tail section on from the other end in that order. Screw down the tail section like you did the bulkhead assembly taking car to make sure it's level with the main fuselage. Now mount the battery in its mount with the battery strap and make sure you have everything (but the wing) is in the state it will be when you intend to fly.

Step 19: Finding the Center of Gravity

First mark a line exactly 1/3 of the chord of the wing from the leading edge. Now that everything is ready but the wing find a friend or a creative mindset because the next step is tricky. You need to move around the wing such that it balances exactly on the line you just drew, then secure it with the screws (you may need to cut some holes). Make sure when you do this the wing is perfectly parallel to the horizontal stabilizer.

Step 20: Wiring

Now wire all of the wires from the control surfaces to the receiver and do some cable management with your tape or zip-ties of choice. Try to avoid excess floppy wire that can get caught on things.

Step 21: Servo Setup

In your transmitter make sure that all of the control surfaces are centered by the servos. Calibrate your esc's and ensure that your servo travels are consistent for each aileron. Make sure none of the controls are reversed and then you should be pretty much ready for flight.

Step 22: FLY!!!

If you are an experienced RC Pilot you likely have your own maiden flight routine but if not here is some advice. Before flying make sure you do lots of research outside of this tutorial (the Flite Test RC planes for beginner's series is excellent) on pre-flights and first steps but my preflight checklist is as follows:

Range Check

Control direction

CG 

Batteries: Transmitter, Plane

Ensure familiarity with switches

Launch the plane by holding it by the rod in front and behind the CG, running with it and launching it as shown in the video (you definitely need a friend for this). Fly around a bit and see how the CG and setup feels. If it needs adjustment or trim, land and take your time making sure everything is set up correctly. Now you have your own airplane!!!