WhirlyDirly // My Custom 3.5" Guarded Frame

By morcmorc on Jul 28, 2022

16  562  6

I guess most drone pilots think about designing their own frame at some point.
This is mine :)

Inspired by KababFPV, Chriss Rosser and StanFPV

Testflight with some crashes

Some flying over concrete

Design Goals

  • Guarded 3.5" platform so you can still continue to fly after a crash
  • As silent as possible
  • Robust but as light as possible
  • Easy maintenance
  • No external HD cam
  • Low vibration


  • 85g Dry Frame Weight
  • 290g AUW
  • 167mm motor to motor (diagonal)
  • 118mm motor to motor (front to back / side to side)
  • 9mm motor bolt pattern
  • 4mm arms, 2mm, 3mm, 4mm or hybrid (2mm full + 2mm half) guards
  • Each arm and guard repaceable seperatly
  • Y shaped arm design
  • 1.5mm top & bottomplate
  • 2x1mm sandwichplate with dampening grease inbetween
  • Stack screws accessible when built
  • Naked DJI airunit to record 1080p onboard
  • Aluminum hardware
  • TPU cam mount
  • Toilet tanked battery


With the currently equipped 2mm guards it recovers well from mild crashes, but it's not unbreakable.
While it bounced off from metal poles several times, one of the front guards cracked after a crash on soft ground.
The same guard then broke after a failed knive edge through trees.

I guess it has a lot to do with the angle of impact.
Head on it holds up pretty well, but at an angle the guards will crack or break around the screwholes.

For me thats still worth it since I can continue to fly after touching a wall in backwards flight, or touching a wire or bouncing of a matal pole and I rather replace a guard than a motor.

I also have some ideas on how to improve the durability of the guards:

  • A different shape (mor oval) than just a cylinder for the carbon spacer over the guard standoff
  • Another 2mm half guard to reinforce the guard in the front and back area

WIll implement that in V2 of the frame.

WhirlyDirly, Baby!



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321   Aug 26, 2022  

Just finished my second frame design and had it cut - both designs being long range 4 inch sub 250g gopro cruisers. Kind of excited about the new build, but completion of the drawings leaves a void in the daily routine. I used FreeCad, which is amazing but it gets slow and difficult to work with over 800 constraints, because it will not run multiple CPU cores. What software did you use to do your drawings, morcmorc, if you don't mind me asking?

Your frame is impressive. What stands out the most is the top down view through the hoops (or should I say whoops) and how clean it looks with minimal infringement of the frame on props airflow. Really, really nice. Keep at it.

morcmorc   Aug 29, 2022 

Thanks mate, glad you like it!! ^^
I started with my main 3D app - 3D Studio MAX. But it's not recommendable for frame design. Then I switched to the free version of Fusion360, and that worked out pretty well. Far less than 800 constraints though :)

wilburfpv01   Aug 16, 2022  

Wow love the way this thing flies (wondering how much the toilet tank config.//3" combo is producing the awesome footage here, especially on the roll axis) I would buy & build one of these from you if it ever becomes available. The concept of just having protected prop guards like this is really all i need for safety on shoots

morcmorc   Aug 16, 2022 

HeyHey. Great to hear - Thanks! After flying and crashing it a lot, I will do another iteration to improve it's weak points (Arm extension and guards). Not that it's really weak, but I know I can improve these! :) After that I'll make it available on CNC Madness.
As for the flight characteristic - Yeah, the COG is pretty perfect in this configuration. No shifting battery back and forth. But I also cranked up the PID's to counter the additional weight on the extremities. P is on 80 now! But since the props/motors are guarded I have no regrets going so high.

dafunk   Aug 11, 2022  


morcmorc   Aug 16, 2022 

Thanks! ^^

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