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Mini Bee sub 250g drone with Mamba F405 part 1/2
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Published
Jan 14 2020 by FaTe
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Back once again in 2020 with drone design number who knows lol. With new regulations stating all drones over 250g must be registered then it seems pretty obvious to build a fully fledged drone with an all up weight (AUW) less than 250g!

So thats the entire concept of this project. The drone must have all my normal features like on screen display, full FPV capabilities and not with a micro video transmitter at only 20w and a short range, no.. 400w and as far as I want is the order of the day. So without further ado on with the show:
/theme/mini bee/1-rough-cuts
I'm using cheap as hell window frame trim from the hardware store. Why? Because its weight per gram is really low, easy to fix and cheap to replace. Additionally its very rigid and resists vibration very well. Carbon fibre? why?!
/theme/mini bee/2-trimmed-bonded
After trimming and sanding came out the epoxy glue. I printed out my template from Rhino and pinned it down. At just 15g the base frame is complete and already very rigid.
/theme/mini bee/3-top-lats-bass-wood
The stand offs provide an area below to house the battery off the ground and will bring the Mamba flight controller inline with the motors for better gyro response.
/theme/mini bee/4-top-panel-bass-wood
At just 15cm / 150mm / 6" long it really is the smallest "Bee" design I've done so far. The top plate and strips are basswood at just 1.5mm thick its quite light and strong.
/theme/mini bee/5-motor-mounts-25g
Last to go on are the motor mount pads at just 15mm square in the same bass wood 1.5mm sheet. All pads are epoxied in place.
/theme/mini bee/6-mini-bee-pattern
Time to break out the paints and attack it with the traditional Bumble Bee dotted theme. Can't say you'd miss this lol.
/theme/mini bee/7-mamba-f405-v2
The Mamba F405 v2 is an excellent flight controller with in built ESC (speed controllers) and on screen display for FPV and if that wasn't enough configurable by Betaflight via USB connection to PC/Phone for configuration.
/theme/mini bee/8-5-8ghz-vtx-camera-installed
Next the FPV camera and 400w Video Transmitter are installed with the SMA antenna port centred to avoid the propellers .
/theme/mini bee/9-mamba-mounted
Now the Mamba can be mounted and connect to VTX / Camera to check everything works.
/theme/mini bee/10-futaba-fasst-sbus-rx-installed
There are cheap alternatives available for radio receivers but given I rely on it to control everything I used my Futaba fasst SBUS receiver.
/theme/mini bee/11-1306-4000kv-motors
Now for the motors. I am using 1306 4000kv drone motors with proper thread orientated shafts so the faster the propeller spins the tighter it'll get. I've experienced propellers leaving at their own will mid flight in the past, it's not fun. Get proper motors!
/theme/mini bee/12-motors-fitted-solder-time
Once fitted its time for the wire jungle to be soldered to the Mamba.
/theme/mini bee/13-motors-soldered-test-phase
Also test the motors with props off and a piece of tape on the shaft. Then you can feel with your finger to check the directions are correct.
/theme/mini bee/14-wiring-tidied-up
My what props you have, said no-one ever. I'm using 5040 (5") tri-blade propellers. I could use a regular propeller but I'd need a higher RPM to achieve lift increasing how loud it is. Just because it's under 250g doesn't mean people won't complain if it screams in the air.
/theme/mini bee/15-finished-188g-exc-battery
All done ready to fly at 188g. That leaves a possible 61g spare for a lipo battery to come in at 249g all up weight (AUW). I'm using 2 cell (2S) 1000mAh 45-90c lipo packs which are... 61g .. wow what a fluke, not. It's been tested indoors and works very well but needs dialled in and a few more tweaks.

Watch out for part 2 with finishing touches and of course the maiden video for better or worse LOL.
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