Tricopter crashes in Poppy flowers - folding arms & how it looks five time in a row!

[Captain Average]

Tricopter crashes in Poppy flowers - folding arms & how it looks five time in a row!

I had one of those days where it kept going wrong. Battery alarm not going off in time to return or not heard, props snapping mid flight, cable ties failing, poor flying and more often than not the arms folding back! I have only just realized that this is what was going wrong on a number of my crashes!

Thought I would share what I've started to learn and how to recognize it.

- A roll starts to happen is the first indication and the throttle response to climb is slower and a dutch roll starts when you slow down

If you keep flying then:
- Speed increases and the nose goes down and back stick has little authority
- Stick response is slow and descent rate increases and instinctively one adds throttle
- Dive fully develops as CofG shifts forward and thrust angle is behind CofG and you are ballistic from here on in so reduce throttle and back stick to cut all motors and stay as flat as possible
- Yaw and momentum is all you have left so pick the soft spots and ride the ballistic arc into the deck!

I have attached a video showing four crashes due to the arms folding to varying degrees and the inverted roll is the motor cable ties going. The last crash along the irrigator went ballistic as soon as I got to the machine and added throttle to climb and all I could do was turn away from the water and just miss the rock pile.

Cable ties, four props and a spare servo fully prepped were the spares I needed to rebuild each time but it wasn't till I got home and reviewed the footage that I saw my shadows and started to join the dots. I did get all the shots but it was embarrassing crashing a dozen times in front of a TV crew but they were impressed by how resilient the machine was!

Cheers
*EDIT*
http://www.youtube.com/watch?v=Ivae2R-Tjbo Crash vid thanks for pointing out my error thedoble

http://youtu.be/TrxxGqspl0E

 

[thedoble]

more often than not the arms folding back! I have only just realized that this is what was going wrong on a number of my crashes!

http://youtu.be/TrxxGqspl0E

I think this was the video you meant to post

http://www.youtube.com/watch?v=Ivae2R-Tjbo

Nice footage in the first one though!

Those were some pretty rough crashes!

A friend made my tricopter's body (to david's design) but he made it out of plastic sheet with aluminum surround, which isn't strong enough and bends 'around' the wooden boom instead of gripping it properly.

Suffice to say my first few flights ended similarly to yours with the wooden booms folding backwards and it all going wrong!

I've since put a new hole through both the frame and the boom and bolted the front two booms in place. This makes them very sturdy, while still being transportable. The downside is a minute or two of set-up which involves bolting and unbolting the arms before and after flights.

I've had two or three major crashes since bolting the front two arms and so far the tailboom has snapped on two occasions, but my front arms are still OK.

Good luck with your copter!

 

[Captain Average]

Cheers for pointing out my mistake mate! Oooops

I drilled out a notch in the front section of my frame but not the arm and now run a 2.5mm cable tie through it that will break with a crash. I have tried locking them forward before with bigger ones and just broken the arms instead. I am not afraid to put this machine in harms way for fun and cool shots.

Does it cartwheel with the front booms locked and snap the back shaft that way or does it slide down backwards. The one where I suddenly flip left broke the tail boom. I also set my yaw mechanism 30mm inboard of the end of my boom and that has saved a lot of servos! I am using the same dibond material (aluminium and plastic biscuit) and am going to convert it to glass sheet with a coarse sanding on my next machine.