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

Specs

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

Verdict

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!

Photos

Part List

Flight Controller	GEPRC GEP-F722-45A AIO - GEPRC (2 builds) Geprc.com	$109.99
Motors	4 x FPVCycle 16mm Motor - 4100Kv (9 builds) Fpvcycle.com	$71.96
Propellers	Gemfan Hurricane 3520 Durable Tri-Blade 3.5" Propeller (2CW+2CCW) - Choose Your ColorYellow (53 builds) Pyrodrone.com	$2.99
FPV Transmitter	Caddx Air Unit - DJI version (4 builds) Rotorama.com	$218.49
Receiver	Happymodel 2.4g ExpressLRS EP2 RX Receiver module (69 builds) Pyrodrone.com	$13.49
Batteries	Tattu 750mAh 4S 95C 14.8V R-Line Lipo Battery Pack with XT30 Plug (4 builds) Genstattu.com	$18.59
Power Distribution	Fettec Spike Absorber - Unmanned Tech UK FPV Shop (10 builds) Unmannedtechshop.co.uk	See Site

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Discussion

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

Big WOW

morcmorc Aug 16, 2022

Thanks! ^^

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