Tricopter Dives => CRASH

[wynnsquad]

Hey guys,

I had some fun this weekend doing some fpv dives with my V3. Unfortunately on my last dive, I guess I pushed it to far because it was unable to pull out and crashed pretty hard.

Here’s what happened:

-250 ft in the air, and went into a nose-down dive.
-Let it fall for about 4-5 seconds with throttle around 1/3.
-Went to pull out by applying more and more throttle, and gently pulling back on the stick
-The V3 started to pull out, but suddenly the right arm “gave out” and the copter went into a roll spin and I was unable to recover.
-biggest regret is that I didn’t have the mobius recording 🙁

So my question is, what did I do wrong (obviously dives aren’t the safest maneuvers to be doing LOL)? Is the V3 capable of doing dives consistently? If so, what are some best practices for doing tricopter dives?

My setup is kk2.1.5, dt750’s, 4S 2200

[wynnsquad]

I was going for something more like this

[biggestRCEfan]

@wynnsquad, I had a similar incident. I did a lot of shallow dives, accelerating to the other side of the field, 180 deg turn, nose down and full throttle to first stopt the movement in the original direction, then accelerate and shallow dive to the other side of the field, and then repeat the sequence. It was a lot of fun, but once, just after take-off, I put the nose down with full throttle to accelerate and climb, heard a “snap” sound. From about 3 meters high, not very fast, it rolled left and forward into the ground.

I found it with the left prop with one blade snapped at the hub. Not sure, but the only explanation I had was that I had a fatigue failure of the prop due to the high loads I put on the props by the accel/decel maneouvres I was doing.

Any similar prop damage on yours?

[hertz]

I guess you’ve got yourself into a vortex ring state where additional throttle only worsened the situation?
The arm “giving out” seems like too much aerodynamic drag on it and/or too high g overload 🙂
P.S. If you want to prevent arms from folding unless due to mechanical stress in a crash, use some zip-ties to hold them in place.

[LeoTheHuman]

I wouldn’t expect VRS during the nose dive, it’s a situation that usually happens in a hover or vertical descend, when you fall directly into the propwash. If you’re moving forward at the same time, as in the video, getting into the VRS is pretty much impossible.

[wynnsquad]

Thanks for the ideas guys. I’m not sure if I had a prop fail or not. When I got to the wreckage, all of my props were equally broken in half.

Do you think that perhaps my controls became saturated? And by that I mean maybe due to the high loads and high G forces at the pull out of the dive, the KK was demanding more power from the motors to maintain stability than the motors could provide.

I’m not exactly sure how much throttle I was giving it at the bottom of the dive (I thought it was near max)but maybe what I was giving it wasn’t enough.

[Spartan]

With it suddenly rolling to one side it just sounds like something failed to me – broken prop, failed ESC etc.

[Author]

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