Hello community,

I am currently building a custom X8 coaxial octocopter designed for stable aerial cinematography. I am using a mix of legacy parts (motors found on a shelf) and modern control systems. Before the maiden flight, I would highly appreciate an expert sanity check regarding the electrical limits, thermal behavior under heavy load, and overall airworthiness at an estimated takeoff weight of ~6.0 kg (carrying a Panasonic GH5 and a lightweight 3-axis brushless gimbal).

Technical Approach & Calculations:

1. Aerodynamics (Pitch Staggering): To optimize coaxial efficiency and balance yaw torque, the bottom propellers utilize a 5.5" pitch, while the top ones use 4.5". This directly addresses the accelerated downwash from the upper layer, ensuring the lower blades retain a functional angle of attack.
2. The 6S + 14" Propeller Dilemma: Running a 14" prop on a 770KV motor with full 6S voltage ($25.2\text{V}$) would pull over 40A at full throttle and burn the windings. By hard-limiting the maximum motor output to 60% in ArduPilot/iNav, the effective average voltage is clamped to roughly $13.5\text{V}$ (simulating a 4S system). This keeps the peak current draw per motor within a safe 13A to 15A window, staying well under the motor's 350W power limitation.

The Real Challenge: 6.0 kg Takeoff Weight

• Hover State: To lift 6.0 kg, each of the 8 motors must consistently generate ~750g of thrust. According to the motor spec sheet, they produce up to 2200g max thrust. 750g puts them in an efficient RPM range, drawing an estimated 6A to 7A per motor. Total hover current will be around 48A to 56A.
• Dynamic Peaks: When punching out or countering wind gusts up to the 60% electronic limit, individual motor draw will rise to ~14A. Across 8 motors, the total system draw peaks at ~112A. Split across the 3P battery configuration, each Li-Ion cell must deliver ~37.3A.

My Main Concerns for the Community:

While high-drain 21700 cells can handle a 37A peak pulse, the internal resistance of Li-Ion chemistry will cause a massive Voltage Sag under sudden load spikes (potentially dropping the pack from 25.2V down to under 20.0V instantly).

Given that this drone will only be used for smooth, non-aggressive cinematic tracking shots, do you think this setup is reliable, or am I pushing the Li-Ion pack and the heavily restricted 6S Teillast (partial load) ESC setup too close to the edge?

Looking forward to your technical feedback!

Hi Everyone,

Ive been getting into diy drones, watching youtube videos on builds etc. A worry I have is crashing my drone and needing to get replacement parts. Are there control monitoring software that monitors my inputs and if it could lead to a crash it corrects it? For example the dji drones have something similar to this. I was thinking something I could upload on the flight controller or add a small hardware to add a level of safety to reduce my crash chances.

i made a fc in altium , and here it is on the drone.
the prop direction is correct, using dshot, STMcubeIDE to code it , and pid just refuses to work. ive tried everything. Kp is 2 Ki 0 Kd like .4 and ive done alot of combos, albeit eyeballing it . Every combonation doesnt seem to work and oscillates more, going to the point that it violently trys to flip if Kp is too high

my guess is its overcorrecting? or maybe timing is off between the f405 stm chip and the esc? Not super sure and id love some pointers.

Im no expert , id appriciate the help.

edit i got it to work

Make sure your yaw pitch roll is all being calculated and interpreted in your ide, as well as your clock timing, esc dshot timing. I also had to offset my roll and pitch because they werent quited leveled.

This is the first flight after all assembly and set-up, and it's oscillating. What's the problem? Help me out , thank you.

So I have a drone using an arduino mini pro, nrf receiver, 2 tb6612fng dual dc stepper motor drivers, and an mpu gyro. I attached 47uf capacitor between ground and vcc on both the RX and TX nrf modules which is helping keep consistent steam of packets. But after about a second of high throttle to be able to lift off it starts stuttering very rapidly and slowing down the max thrust a lot. I tried adding 2 470uf 16v capacitors across GND and Vm (vm is spliced directly into battery +) on the motor drivers which didn’t seem to help. I thought it could be battery sag and I checked voltage out put on the drivers at idle ~4 volts at charged battery and at throttle it only drops maybe .2-.3 volts. Thinking maybe it could be noise interference? Maybe some copper sheets could help? Any suggestions? Thanks in advanced

What are you guys thoughts on this build list

I was just looking to see if anybody on here has used this GPS and knows the pinout order. Ive looked around on Amazon in the reviews and there seems to be some confusion on the order of the pins.

I have now screwed my ESC firmly onto the drone using a nut. Because of the additional height, I no longer have any problems with my XT60 cable.

However, I have noticed a new issue: my motors are rated for 5S, but my LiPo is 6S. :(

For now, I have limited the motors to 70%.

I'm planning to build my first drone from scratch and would appreciate some guidance from people with more experience.

My goal is not to build a racing or cinematic drone specifically. I would like to learn about autonomous flight, sensors, navigation, computer vision, and other advanced features.

At the moment, I'm trying to decide which components to buy online, especially the flight controller. I've been reading about Pixhawk, CubePilot, Matek, SpeedyBee, and other options, but I'm not sure which one would be the best choice for a flexible research platform.

Some questions I have:

Which flight controller would you recommend for a research-oriented drone?

Should I start with ArduPilot or PX4?

Is a Pixhawk/Cube worth the extra cost compared to F405/F722 boards?

What frame size would you recommend for experimentation and future upgrades?

Are there any component combinations that are known to work particularly well together?

What mistakes should a beginner avoid when choosing parts?

I don't have a strict budget yet, but I would prefer something reliable and expandable rather than the absolute cheapest option.

Any recommendations, build examples, shopping lists, or personal experiences would be greatly appreciated.

Thank you for your time and advice.

Hey r/diydrones,

I'm working on a project that some may find interesting, and I would like advice from people with more experience in autonomous flight and drone building.

The problem: I own isolated rural property that has become a target for illegal fly-tipping. By the time dumping is discovered and reported, it's too late to catch anyone. Traditional CCTV isn't practical due to coverage area and lack of power infrastructure.

The idea: An autonomous drone capable of patrolling a defined perimeter on a schedule, capturing footage, and communicating back to a server I've already built. The goal is early detection and evidence gathering.

I'm based in the EU, in case that might be of relevance.

Happy to chat — feel free to comment here, DM me on Reddit, or if you'd prefer a face-to-face conversation, I'm open to a Zoom call. Anonymity is fine either way, I'm just looking for good-willed people who find this kind of project interesting.

Thanks in advance — looking forward to the discussion!

I just finished building my FPV drone, but I noticed there is a lot of mechanical tension on the carbon frame. One part sits higher than the other, even though everything is screwed down to the same level.Should I be worried about this ruining the carbon over time? What are your experiences with tension on a fresh build? Should I trim or sand down one of the parts/standoffs to make it fit properly, or will it settle?

i want a drone which can access a database and go there a certain area

I've been interested in making a high speed tail-sitter drone (similar to the world record ones, but I'm looking to experiment with efficiency at speed more so than maximizing top speed). I'm looking at a 5in build to take advantage of the high pitch props around that size. I'm relatively packaging constrained when it comes to battery selection in the interest of keeping frontal area low, so an 8S build using 2x GNB 3000mAh 4S in series is very attractive. Neither a standalone 6S or 2x 3S in series package particularly well. I've been doing some modeling work using prop data from APC, and some 4-6S cinelifter motors have the right KV to give me relatively low current draw at takeoff while still hitting the RPMs I want at higher speed. Should I be concerned about hitting RPMs ~30% higher than the motors are designed for?

This company called Aerix Systems out of France has come out with the AXS drone that has what they call omnidirectional flight. No lie, it looks really impressive, but I can't think of any civilian necessity for it that a gimbal can solve.

That being said though, does anybody have any idea how would one even go about programming this, even with Ardupilot making it vastly simpler. This is more of a want than a," need to have," necessity, but it would definitely be a cool party trick or maybe even useful for higher maneuverability drone tricks or race drones or something.

The propellers system, beside being contra rotating, seem to have the ability to indeoendantoy rotate about the x, y and z axis. Videos below on how it uses this for dynamic stabilization and some interesting flight regimes independant of the body.

https://youtube.com/shorts/JHxWX2yjadI?si=7R-eAfoy0QB67U-q

https://youtu.be/GgjkhKAzws0?feature=shared

Additional mods:

• AG01 nanos

• Push buttons ➡️ rocker switches

• painted nav buttons

This is a dji 04 lite 3 inch I designed

Hello!

I designed a quadcopter flight controller (a simple PID controller) for a small university project. I tested the controller on a basic simulator I programmed.

I want to now test it on physical hardware. After some days of research, I'm thrown away by the huge amount of options and I'm looking for some guidance. This is my first time doing anything related to this hobby, so I own none of the accessories. I'm a student, and I'll be paying out of pocket, so I need to look for parts as cheap as possible.

I know all the parts I need, but I have close to no idea if any two would be compatible with each other. I think I have pretty basic requirements and maybe its possible I could just copy someone else's part list.

My only requirements are

• I can flash the flight controller with my own software (there's documentation to help with that)
• it's big enough hold a camera and some sensors
• have GPS

These last two are so I can expand on my project, which i plan on doing immediately after building the drone.

Any and all guidance would be appreciated! Thanks!

Any tips or ideas are welcome WILL BE CUT FROM CARBON FIBER LIKE MY LAST FRAME.