Designing a Ridiculously Fast Fpv Drone (~180mph)

In this project, I set out to design and build an FPV drone with one primary goal: speed.

I was inspired by the high performance racing drone developed by Red Bull for Formula 1 events, and I wanted to create something similar using accessible amazon components. My previous FPV drone was capable of reaching 140 mph, so I used many of those electronics as a starting point and pushed the design further.

This project involves custom frame modifications, aerodynamic design, and careful component placement to maximize performance.

Skills required:

1. Basic soldering (highly recommended to practice beforehand)
2. Beginner to intermediate 3D modeling (unless using identical parts)

supplies:

1. video transmitter (vtx) + camera (DJI 04 air unit)
2. 4 motors (xing-e pro 2207)
3. carbon fiber fpv drone frame(the one I used is attached)
4. electronic speed controller (ESC) (speedybee f405 stack)
5. flight computer (speedybeef405 stack)
6. radio reciever (radiomaster 2.4 ghz elrs)
7. battery (cnhl 1500 mAh 6 cells)
8. propellers (any 5 inch)
9. fpv headset (dji goggles integra)
10. radio controller (radiomaster zorro)
11. xt60 connector
12. capacitor (1000 microfarad, 35V)
13. a bunch of screws (particularly m3) and screwdrivers
14. pla
15. threaded heat inserts (m3)
16. miscellaneous wires
17. tape

tools/software:

1. soldering iron
2. LiPo battery charger
3. callipers
4. 3d printer
5. fusion 360
6. betafight
7. DJI Assistant 2 (Consumer edition)
8. ExpressLRS configurator
9. slicer (I used bambu studio)
10. drill + rotary saw attachment

To reduce drag and improve high speed stability, I modified the frame by cutting excess material and making it more compact.

Assemble the carbon fiber frame and after that using a saw attachment for your drill, cut the rectangular parts of the frame. so that it looks more like a square. Make sure to cut the top and bottom part of the frame. Also make sure you do this outside, and wear a face mask to ensure that carbon fiber dust doesn't enter your lungs.

Solder motors to the ESC:

Solder up the motor wires. The order doesn't matter. If you never soldered before, I recommend you to order a practice soldering board off of amazon.

Solder the xt60 connector and capacitor up to the battery pads on the ESC:

This is the hardest step because soldering on big pads is quite difficult. A few tips: use the biggest soldering tip and the highest temperature, and let the iron rest on the pad for like 15 seconds to fully heat up the pad. Make sure that the red wire goes to positive (+) and the black one to negative (-). Also add the capacitor to the battery pads. The capacitor is needed to reduce voltage spikes, which is critical at high speeds because it prevents esc failure. Once again make sure that negative goes to negative and positive to positive.

Solder the radio receiver to the flight computer:

Look at the schematic for your particular receiver and flight controller. Solder from reciever to flight controller respectively: (gnd -> gnd; Power ->5v; Tx -> R2; Rx ->T2).

Solder the vtx to the flight computer:

Look at the schematic for your vtx and flight controller again and solder respectively: (gnd -> gnd; power -> 9v; Rx -> T1; Tx -> R1)

Taking measurements:

Using calipers take measurements of the electronic components you need to mount (VTX, Reciever, Battery, and camera).

Also using calipers take measurements of the of the screw holes on your frame as they will be holding your mounts.

Sketch your measurements on a piece of paper. Remember to add 0.2 mm allowances, so that the part fits when you 3d print it.

Then hop into fusion 360

Designing the component mounts in fusion:

I recommend first printing out only the screw holes part to test out if they fit. You can then construct the rest of the mount. If it's a little loose, add tape to ensure that the component doesn't fall out mid flight. You will also fail a lot, and redesign your components several times.

Designing the top and bottom aerodynamic shells:

At speeds approaching 180 mph, aerodynamics becomes one of the most important factors. Instead of using a standard open-frame design, I created a fully enclosed aerodynamic shell.

Once again use the screw holes on your frame as places to mount the shell. I messed up a lot on this step, particularly with the top aerodynamic shell. All the electronics except the vtx and receiver go in there. Make sure to also have a hole for the fpv camera.

I used the Bambu labs p1s as my 3d printer. The filament I used was pla because it's easy to work with, plenty strong, and light weight. Also I sanded the top and bottom shells to ensure maximum aerodynamics.

Placing threaded inserts onto camera mount:

I used 350 degrees Celsius as the temperature on my soldering iron. It takes almost a minute to fully push the inserts into their spot.

Screw in all the mounts and aerodynamic shells to the frame.

Flash your DJI 03 air unit and goggles to the latest firmware using the DJI assistant 2 (consumer series) app. After that go into your goggles settings, press bind, power up the drone, and then follow the steps.

Flash your receiver using ExpressLRS Configurator. Select your exact model of receiver in the menu and follow all the given steps. After that go to your radio controller and is the system settings menu select ExpressLRS and then press bind, then replug your battery 3 times to enter into bind mode on your receiver, then wait to bind.

First plug in a usbc cable from your computer to the flight computer. Make sure its a data cable.

In the setup tab make sure to calibrate the accelerometer.

Next, in the modes tab make sure to select what channel (switch on your controller) you want to use to ARM the drone (basically make the motors start spinning).

After that go to the ports tab and enable UART 1 (this enables your radio receiver). And select serial rx for UART 2. (this enables the vtx).

Then go to the motors tab, plug in the battery, and following the diagram, make sure that the motors are in proper orientation, and spinning the correct direction. If not, press reorder the motors or motor direction respectively. MAKE SURE TO TAKE OFF PROPELLERS WHEN DOING THIS. Also when putting on propellers keep in mind that order matters. Propellers at position 1 and 4 should spin clockwise, while 2 and 3 should spin counterclockwise.

Please keep in mind that this is just the most basic betaflight setup because there is so much to cover, so if you want more features, such as flip over after crash, there are plenty of other tutorials.

If you never flown fpv drones before, this step is a must, because flying fpv drones is quite complicated, so you need virtual practice. FPV skydive is a good free simulator, and TRYP FPV is a good paid one (both are on steam). Both are available for Mac and Windows, however TRYP is quite GPU intensive. You will also need a radio controller for the simulator, which you connect to your computer. I recommend at least 10 hours in the simulator before your first flight. If you are a veteran fpv pilot, then flying this drone is not that different form any other fpv drone.

During testing, I experienced signal loss and crashed the drone. While frustrating, this revealed a critical design flaw.

After I few about 100 yards, the radio lost signal and the drone crashed. Crashing is nothing new to any seasoned fpv pilot and I was extremely lucky that none of the electronic components other than the battery broke, and it was quite simple to rebuild

I realized that the receiver's antenna was too close to the vtx, getting interference, and on top of that it was covered by plastic. The redesign was quite simple. I just had to design a hole in the bottom part of the shell of the drone. After I fixed it, the drone was able to go at least 5 football fields away.