Initial EDF power-up

I soldered up the motor and ESC connectors for each, to check they all work. I hooked up a 12V 18A power supply (the biggest I have) and used the servo tester to provide the control signal. The first one ran the wrong way as I had the motor connections swapped - easily sorted (and now labelled). I couldn't spin them up to max because the PSU hit current limit and the voltage sagged to a point where the ESCs cut out, but wow, I was impressed! They each seemed pretty well balanced up until just before the cut-off point where some high frequency vibration was observed. Can't wait to run them properly, so I'll have a crack at balancing them next, and fixing them into a triangular test rig. To run all three at once; I'll need a higher power PSU too.

System Block Diagram

Here's my first draft of the system block diagram. It will help me see the bigger picture when working on the system components. These are just a brain-dump and aren't set in stone.

eBay update

My 3.5mm gold connectors and servo/ESC tester have arrived. Will give the tester a go tomorrow, try to get an EDF going.

EDFs arrive!

A smaller than exected parcel was on my desk when I got home from work today. Inside were the three plastic fans/housing with motors already mounted and aluminium radial cooling fans on the back. There was even a small Allen key supplied for each. Also in the box were three 40A ESCs complete with BEC and a small bag with mating half connectors and heatshrink tubing, even though the eBay lot was shown and described as "no connectors" (9 days from Hong Kong!). There was also the "free gifts" - three mini keyring torches, which I may rob the LEDs from. I inspected each of the EDF units for transit damage and all looked OK.

I haven't currently got a way of providing the ESCs with a signal so I can't test them yet (servo tester on order). There was a little plastic flash from the injection moulding process which was easily trimmed with my trusty Swiss Army knife. I guess they'll need balancing before I stick any serious power through them. Can't wait to try them!

Make Magazine - good timing

The latest issue of Make came through, with a UAV theme! They put me on to DIY Drones, which I'll have to check out properly, along with RC Groups.

Links in the sidebar >>

EDFs, BLDC motors and ESCs

On past projects I'd always try to do everything for the absolute bare minimum in terms of money spent. This often lead to long delays as I had to do everything the hard way. This time round I've had to admit that I shouldn't re-invent the wheel (making my own ESCs for example) when I can make better progress by using off the shelf components and stitch it all together with my own stuff where needed.

Even though Dave Powers says that VTOL with EDFs is very difficult to do (and he has much more experience than I do), I still feel it's within my ability. And after all, I do seem to like to make life difficult for myself!

eBay!

I found some 90mm EDF units complete with 3600kV BLDC motor and 40A ESC for a very reasonable price on eBay. They're from Hong Kong, so when they finally arrive, they may not be the best, quality wise, but they'll get me started. I've got three sets on order, for about the same price as one set if bought separately through hobby websites or high street hobby shops. eBay has also provided:

• 2 pairs of mechanical retracts for the landing gear.
• 20 pairs of 3.5mm gold connectors for motors/ESCs.
• Servo tester to aid early tests and setup.

I won't need batteries and charger until much later, I'll use an umbilical during development. I think most of the construction will use carbon tube, balsa and plastic sheet and extrusions.

Fingers-crossed everything turns up, and in working order.

Scribbles for my mind

To help me get things straight in my mind, I sketch with that old fashioned pen and paper stuff! I have to get a feel for whether I could make it without huge complications or expense.

I thought about props and motors for lift but I wasn't quite happy with the look that they would give. I really wanted something like a ducted fan, so I Googled. I found EDFs (electric ducted fans) that hadn't really been around (common or affordable at least) when I was last crashing RC aircraft. I found the largest size, common enough not to be "specialist", was about 90mm diameter and could provide well over 1Kg of thrust. Not bad.

In order to see what was out there and how things had changed, I searched YouTube. I found Dave Powers and Co (of rcpowers.com) doing some really useful guides and general videos proving that RC planes don't have to be perfect precision machines in order to fly. Dave regularly uses tape, glue and junk to get his aircraft back in the sky. He earns the first linky-link in the sidebar ;-). Check out his videos.

Project Intro

For fun, I'd like to scratch build a VTOL platform that self stabilises (not requiring input from a human), is capapable of autonomous take-off and landing and can be used as an "eye in the sky" as well as for fun. I'm not going after long ranges or runtimes, but do fancy a bit of a Sci-fi look.

It will take a range of skills and fair amount of cash - lets hope I have enough of both! I have limited experience with RC planes and helis, and that was a while ago too. Google and YouTube are my research friends. I plan to log it all here, but I'm making no guarantees that it will ever fly.