We've all been there - a rainy afternoon, bored, and need something to do. This is my effort. Trawled the parts bin and drawers for old and discarded parts to build this - my smallest and cheapest cargo delivery drone.
I normally build 2-8kg units for customers; our latest EPM-based unit is rated for 30kg. But today...it's somewhat less than this. And somewhat cheaper too.
This little 450 size unit can carry about 400-500g a range of 2km and back on a single 5000mah 3S. Just. You'll be on the alarm...
Ok, so parts:
Frame: A cloner F450
Motors& ESC's: A combo pack of 2212's and 20A ESC from Hobbyking. They're awful. But they work.
Props: 1045 CF RCtimers (balancing nightmare btw)
FC: APM 2.72 + 3DR 6M (road rashed) + 3DR PM + 433 telemetry/OSD combo. (telemetry useless beyond 40ft btw).
Payload system: EPM 2.5 + our carbon mounting plate and camera boom
Cameras: 2x PZ0420
FPV Switcher: Hobbyking cheap and cheerful
Receiver: Frsky D4R-II (PPM mode)
VTX: 5.8, 200mw + ibcrazy antenna.
5V BEC: Polulu.
All in all...about $300 in parts. Your mileage may vary, depending on how much you have to buy new.
FC: Arducopter 3.2.1
It's a basic quad config, with two changes:
- A10 is either CH8 passthrough or EPM control, depending on whether you're doing manual or autonomous drops
- A9 is straight passthrough for CH6, for the FPV camera switcher (to switch between flight and bomber cams)
2x cameras on a switcher. Flight cam has OSD.
- EPM powered from 5V Polulu,with PWM connected to A10* (see below)
Ok, don't expect miracles here. It can do an out and back payload drop of a small medical pack (pictured) to around 2km and back again on a single pack, at 1'c ambient @ 800m ASL. Limitation is the battery, not the radios - both control and FPV are still working well at this range. You need a 5-8 turn helical on the ground for the video though.
Gets really sluggish in stabilise or Poshold with the load on. Hover is about 65%.
- EPM command still executes way too early in auto mode. You need to adjust mission to ensure EPM command happens after a waypoint. Also, on some runs, the EPM is still firing when it returns home.
- I lost an entire evening debugging the Payloader PWM. It refused to work. Only to discover I had it in A9 (and the FPV switcher in A8). Facepalms all round.
This unit will now be "retired" - it's retirement duties will now revolve around dropping the CEO's dogs toys during walks...