Nuts

[DethWshBkr]

Flying around here this afternoon, and she went in.

Not exactly sure what happened either. It was not an "oops" on my part, but some failure.
I was tail in, going down flat, and I popped the collective. It appeared as though something came off and went left, and she started a full speed counter clockwise rotation. I had enough time and wits about me to analyze and attempt three saves, but to no avail.

First - I simply attempted to control it. Of course to no good luck. I thought I would try to hold it steady (as fast as it was spinning, there was no cyclic control anyway) until the fuel burned up. I was half way down the header tank, so only another 20-30 seconds or so.

Second - after figuring I did not have 20-30 seconds until impact, I attempted a throttle hold. NO RESPONSE. I tried it again, but no response.

Third - throttle kill. I have my "left trim" switch set as a momentary kill. I held the button up, and for a good few seconds. This would have been more than enough time to stop the engine completely, but there was NO RESPONSE from the engine.

Finally she started tilting a little bit and just went in. Full throttle (Idle 2) Pieces went flying and the engine died immediately.

Damage is only the physical airframe itself. No electronics damage that I can make out. The receiver pack was not in the mess, but about 20 feet away. I am wondering if the receiver pack somehow came out. I cannot see how it would have made it out of the canopy, but the lack of response from the tail IMMEDIATELY after the "item" came off indicated it could have been the gyro losing all power and she just went spinning.
I did not look immediately after the thing came off, at the item, I was just concerned about trying to kill the engine and arrest the tail spinning so I could auto it in.

Can anyone think of any other things that would have caused this other than pure lack of receiver battery?

Damage is as follows -

Canopy
Landing Skids
Carbon Boom
Torque Tube
Header tank support
Flybar
Flybar paddles
Rear blades (precautionary replacement)
Main blades
Tail Rod guide block
Long receiver frame





-The main frame is in perfect condition (tough sucker!!)
-The boom supports themselves are in perfect condition, but the plastic inserts that bolt onto the frame and tail are broken (surprised those long aluminum tubes are perfect)
-The main gear and torque tube gears are fine. (main gear?! wow....considering it was WOT.)
-Main shaft appears to be perfect, but it and the feathering shaft will get chucked onto a lathe and checked.

[YBNORMAL]

That stinks...........were any wires pulled out when you got to the bird, did you find anything missing?

I would think that if you lost power due to a battery launch, that you wouldn't find it still strapped in....edit: just reread you OP and you said the Rx was launched.

What about an on/off switch failure? It does seem to me like loss of electrical power caused the crash. Loss of power to only the tail gyro would still allow you control of your throttle.

I wonder if the throttle hold function is tied into a gyro/gov all-in-one type of unit (I don't know what your running, I am thinking of a 701 for my build). If it is, and you are running an all in one, we could be back to just the gyro loosing power.



YB

[DethWshBkr]

The On/Off switch was half way or so when I got it home, but I mean, after the impact, I can believe it was moved. It is a large, heavy duty switch that is completely unable to be bumped in any way, and has a firm switching action. i thought about this, but I HIGHLY doubt that was an issue. Aside from that - SOMETHING came out or off of the heli, and IMMEDIATELY began to spin. This tells me it could easily have been a power failure, especially if the battery pack did eject.

The more I play it back in my head, the more I am convinced the receiver pack somehow became dislodged and ejected from under the canopy, which caused a full loss of all electrical power and obviously tail control.
This is also the first time I ran 30% nitro fuel, it's been two gallons of 15%. I can not believe the increase in snap and power this thing had. I was upside-down, pulling away and up on negative collective and not bogging at all, and I am also beginning to believe that my receiver pack installation was not sufficient for this extra amount of power and g-forces put on it by the increased power, also causing the pack to come out.

I can accept this crash if know WHY it occurred. What scares me, is not knowing what caused it. But yeah, more and more, I am thinking it was a receiver pack coming out, and causing total power loss.

[DethWshBkr]

What about canopies?

I like a stock looking machine, but $70 for the stock canopy seems steep. Canomod has the Voltage for $50, but I do not like the looks quite as much.

Any other options?

[Elgyn]

check the voltage on the reciver pack to. It might be low

[KouDy]

What receiver pack are you using?

Stock canopy is 52USD without shipping.

[DethWshBkr]

Pack was showing 6.3 according to my telemetry. It was freshly charged too.

I did get it all apart last night, re-ran all of my wires and function tested it. All servos, functions, gyro and governor are working normally.

The pack is just a 5 cell Nickel Metal Hydride pack. It is still showing very high charge.

The only thing that makes sense is the pack coming out.

[darryl123]

i had a tail drive pin fall out on my 90 and it spun so fast the rx pack came out and unpluged.