roxblog: 2019

UPDATE 1/1/2017 Due to new legislation about drones I cannot fly my drones any more because they need an airworthiness certificate from Hellenic Civil Aviation Authority. Never mind, the costly Li-Pos are already exhausted and I thing it is about time to move my autonomous vehicle interests to other more legal regions :) .So far so good then, I learned a lot about autonomous vehicles and most certain I HAD A BIG FUN FLYING THEM (and a huge aerial photo collection).

Ok let's admit it. Can somebody who likes microprocessors, GPS's and high tec electronics stay away from drones? Nay !!!! So I entered this uncharted region plenty of fear due to the fact that I had once lost a model airplane due to my ignorance of how to fly model airplanes. However I have no fear at all to make a car - ship - airplane - drone -submarine - whatever. So I acquired some aluminum plates, bars, tubes and 3mm inox allen screws and bolts, purchased from E-bay motors , propellers, batteries , autopilots ,GPS , telemetry modules and here it is.... my first drone back in 2013 IN FLIGHT !!!

First quad in flight - RIP

RIP ??? How's that ? Well , I went totally unprepared, without on board pilot camera, no video link, just a simple short range bluetooth telemetry, a 1HZ GPS module (the late EM406) which took for ever to lock , no failsafe programmed on autopilot, on a windy day to a mission which seamed very easy, very close to my house. Failsafe was a nuisance to program and once the quad returned to launch (RTL) on his own and crashed before I understand what happened. I flew it without gps lock and when it got over 30m it drifted away due to strong winds. I tried to bring it back but since I had no colored stripes (or colored propellers) on any of the arms to know where it was heading , I drove it further away and it just disappeared from view towards a hilly forested area. Needless to say that my flying skills were (and still are) NULL.

The broken propeller issue and Murphy’s Law

"Even if you fly in a totally bushed area your drone is going to crash on that single rock between the bushes." The frame below shows the propeller blade separating and causing a drone crash. At first I thought that responsible for the crash was some kind of RF interference. The on board video camera caught the culprit : We had an in-flight propeller blade separation.

propeller blade separating

...and that single rock

Quad MK II

After considering more seriously about flying drones I assembled the MKII. It still flies today (2016) despite a few crashes that costed me no more than a few propellers and some twisted aluminum arms and plates. Here it is:

Quad MK II

Lessons learnt

Don' t use cheap 9.6 inch propellers on a 1.5kg drone - they use to flip on air (happened to me twice).
Cheap batteries have unexpected behavior .
Use video link and a camera for the pilot
Wind velocity rises dramatically 30m or higher or when clear of trees or houses.
Schedule your mission very carefully
Be sure that telemetry and osd video are working
Do a range test
Check for RF interference
Program failsafes
Wait for the gps to lock.
Stay away from people -cars -airplanes and generally urban areas - 1.5 kilos is not a negligible weight when falling from 70m
Do preflight tests based on a thoughtful prepared list
Connect the battery low warning buzzer
Put a lost model module buzzer on an unused channel
Write you phone number on the drone.
Use different color for the drones back arms.
If you 're not a competent pilot, then let the electronics fly it for you - believe me they can do it both economically and safer too.

I decided to fix some of the problems discovered during the first and second drone development.

The drone should have ample space for the onboard electronics and they must be accessible without major strip down.
Video camera - the excellent Mobius actioncam - should be on a proper gimbal offering unobstructed front view and placed well away from the propellers.
The drone must be foldable and could be easily carried in a plastic tube of 15cm diameter.
Battery must not hit the ground, but it must be housed and protected inside a frame, and able to be moved to adjust the CG of the air-frame. (this is accomplished by using velcro straps)

The new drone named MARK V (MK V) was designed back in 2015 from scratch using a CAD software .
3mm and 0.8 mm aluminum was used for the baseplates and 1x1 1.2mm aluminum "Pi" frame for the arms.
Notice the orange colored tape on the back legs .....