RTL fly away...

Yesterday I went away to find a field large enough to do some serious RTL (return to launch) and navigation testing. This requires space without trees too close. I found some nice fields and started testing. I successfully tested both RTL and three way point navigation before my last RTL went sour...

I flew quite far away as I previously had done and hit the RTL. The normal procedure then is for the quad to gain height to 15 meters, which is default. Then head to its home position and descend to about 3 meters and loiter. This time, instead of turning towards home, it started drifting to the left. I quickly intervened to save the quad by counter steering rightwards. The quad then rotated 90-180 degrees making the direction impossible to see from this distance and disappeared behind those trees according to the drawing. I then ran towards the highway and never saw it again.

I've since then been covering the grounds around the point where it disappeared for about 8 hours in total, checking trees and the ground where it might have crashed without result.

It might have kept going in that direction ending up on the other side of the field as the program does not include anything about landing, but keeping 15 meters until the destination has been reached. It might also have taken a short trip on the field, then turned around ending up somewhere else. I still think the highest possibility is that it sitting in one of those trees along the highway.

Later today or tomorrow, I'm going to print posters asking people to contact me if they find my quad. Hope that gives some results. At this point, I don't think I can afford a new one, which leaves me with a pile of spare parts that will not be used..

Packages packages, more packages and washers

 

This came in the mail today. It's the order for new motors and 8 inch propellers. Having smaller propellers also eases the torch on the motors, which should lessen the overheat.

Now I might have come to a conclusion why my motors are failing. Due to the nature of aluminum, its quite weak. Now as the screws that hold the motor in place slightly bends the aluminum inwards, the top of the screw seem to get scewed too far into the motor and may cause a short circuit.

To counter this condition, I've bought some washers. These washers are used both to protect the aluminum from bending too far and also to put some distance between the top of the screw to the motor. I also bought some locking washers to keep the screws in place keeping them from coming loose due to vibrations.

This is the end result, now only time can tell if it works or not. Will try this out tonight along with the 8 inch propellers.

Ultrasonic range finder and stuff

My trials with the ultrasonic range finder shows that it doesn't get too much interference from the other electronics that are located close by. I still made the rookie mistake by connecting the Echo and Trigger cable the wrong way around and spent much time trying to figure out what was wrong until I figured it out. I've also tried to activate AltHold while having the range finder activated. Didn't see much difference in it's behavior but it'll be essential for automatic landings.

Also, yet another motor has started showing signs of problem. It's slaming back and forth before spinning up but doesn't seem too big of an issue with that. However, after running for a while, 5-7 minutes, it gets really hot while the other three motors stay cool. I'm wondering why I'm having these problems with the motors all the time :(. Therefore I've made another order for more spare motors and I also threw in some more propellers. This time 8 inch x 4.5 propellers. Will try and see if these propellers are more suitable for the quads weight.