Nano mystery

[BladesinMD]

Ok folks so I had a strange thing happen today and need some help figuring out what is going on.

I have flown approximately 70 packs through my Nano, all have been indoors until today.
I have 4 EFlite batteries, the two that came with the heli and two I bought new at a later date.

My nano has the MicroHeli aluminum swash, head, blade grips, and anti rotation bracket. Brushed motors, DX6i.

It was about 37 degrees F outside. I let the heli sit in the cold for over an hour before flying. (the batteries stayed inside).

First flight went fine, flew about half in idle up mode, no problems. This was one of the newer batteries which seems to perform better than the older ones (consistent with other reports when using the stock charger (mine has the AC adapter))

I waited about 15 minutes and ran the second battery, which was one of the older batteries.

Before I continue it should be noted I have run this battery indoors and in idle up mode (without stunts, for practice) with no issue running 4 to 4.5 minutes.

So about 30 seconds into the flight, I switch to idle up, about 2 minutes 45 seconds in, I am hovering inverted and the heli bogs down so bad that it (softly) hits the grass. I pick the heli up and it beeps three times at me. No physical damage detected.

After inspection I reinsert battery for another flight, all swash responses look normal when I test with throttle hold on, HOWEVER, the problem is when throttle hold is off and I throttle up to take off, the swash pitches forward and I cannot correct for it. No matter what I try, the blades hit the dirt and heli will not lift off.

I held the heli to see the swash action and confirmed the swash pitches forward.
Servos seem to be OK and there is no vibration issue that I can tell.

I should note that I have had the famous tail wag issue which nearly disappears in idle up mode. The spindle is straight, no cracks in the tail boom, no damage to main shaft.

Is this a bad gyro? A bad main motor?

Any thoughts from you folks appreciated. I'd like to get my bird flying again...

Thanks

[BladesinMD]

No one?

Am i missing something obvious here?

[BladesinMD]

Here is a video of the issue..

http://vid1058.photobucket.com/album...psf8esiee4.mp4

[ToddMcF2002]

I'm thinking it could be 1 of 2 things:

1. FBL thinks level is steeply to the right and tries to reach it on spool up. When I've seen mine get funky like this cycling batteries usually cures it. Obviously you tried that. Have you tried a rebind? And you are on a level surface when you plug in the lipo?

2. Just to rule out the servo being bad I'd swap aileron and pitch servos. If it starts tilting left then you simply have a bad servo.

I think #2 is the likely answer....

[BladesinMD]

Originally Posted by ToddMcF2002

I'm thinking it could be 1 of 2 things:

1. FBL thinks level is steeply to the right and tries to reach it on spool up. When I've seen mine get funky like this cycling batteries usually cures it. Obviously you tried that. Have you tried a rebind? And you are on a level surface when you plug in the lipo?

2. Just to rule out the servo being bad I'd swap aileron and pitch servos. If it starts tilting left then you simply have a bad servo.

I think #2 is the likely answer....

Thanks for the reply.

I tried everything in No. 1 to no avail.

As for No. 2, because I am getting down on the right servo and up on the left I don't think it is a servo issue. All pre-flight servo responses are good too. No hangups.

I think there may be some vibration that I cannot detect from my testing. Tonight I am going to unplug the tail and see if the issue persists.

If not, I have a replacement main shaft I will install and see if that helps - maybe there is a splinter that I cannot detect.

This is a similar reaction to vibration as I got from my 450x from unbalanced tail rotors. The so-called "Right Roll of Death".

[mattbeau]

Mine was doing this the servo was dirty and a little contact cleaner resolved it. Mine was flying all over the place after I sprayed it down it settled right down


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[BladesinMD]

I replaced the main shaft this evening to see if that made a difference and it does not.

I am starting to think this is a main board issue. Sometimes I don't get any response from the cyclic in left or right (the servos that are acting up) but I always get a reaction from the rear (pitch) servo.

I'm disappointed as I haven't had any real bad crashes with the heli and I was just getting to begin inverted practice outside the simulator and I have an unusable helicopter that I have unnecessary replacement parts on.

I'll call HH tomorrow to see if they have anything to say.

[jbrandt]

Originally Posted by mattbeau

Mine was doing this the servo was dirty and a little contact cleaner resolved it. Mine was flying all over the place after I sprayed it down it settled right down


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Nice one. Dirty servos can manifest as many weird issues. Mine would "jitter" mid flight randomly. Some electronics spray cleaned it right up.

It's an easy thing to try and just assume your servos could use a cleaning anyway.

[Mugen2008]

If it's not a dirty servo, try swapping the left and right servos to see if it's a signal issue from the 3in1. Also consider a problem with the tail wire touching a servo linkage or other metal parts.

[BladesinMD]

So I talked to HH today, they agree that it is the 3 in 1. A new one is on its way, I have little doubt, this is my issue.

[BladesinMD]

So the problem was my transmitter (DX6i). No idea why all of a sudden it caused this issue, but it happened even if no motors were turning.

I reprogrammed the transmitter and viola! she is back to normal.

I got a new 3 in 1 installed, but that was not the problem. Guess I've got a spare now!

Very strange...

[kfjensen]

At 37 degrees I would expect that you may have also been hitting LVC before 3 minutes flight time. I'm lucky to get 2 minutes out of a battery at about 20 degrees before it bogs down. If you are on the original main motor it could be on the way out, mine lasted about 25 flights.

The 3 in 1 boards do seem to operate differently with lower temps. Hopefully it was only your transmitter as you say. Although there aren't many complaints about this with the nano, check out the the thread about bad mainboards in the 130x forum to see if this seems familiar https://www.helifreak.com/showthread.php?t=462484

[turko]

My mcpxbl exhibits the eact same behavior, when I'm spooling up the right servo drops.And you say its the Dx6i? I'm also using the Dx6i and my heli started doing this yesterday.

[BladesinMD]

Yes, Turko.

Try completely reprogramming the DX6i. I created a new model and deleted the old model after I tested the reprogram.

Let me know if it works.

Were you running in cold weather?