Tail problems - HeliFreak
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Old 03-31-2017, 04:23 PM   #1 (permalink)
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Join Date: Dec 2016
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Default Tail problems

I've been having tail problems with my new BNF that come and go. I thought the issue was a loose gear, so I used white craft glue on the gear, and no problems until I crashed today and the gear came loose again. So I put a new one in immediately after the crash and the tail problems are back.

The issue is that it feels really loose on takeoff, wagging a bit even in no-wind. On IU pitch pumps it goes 10-30 degrees to the right going up, same to the left going down. On normal mode, it's about the same going up, but going down it goes waaaaay clockwise, like 90 degrees or more. If I put it up high and kick throttle down to 1/4, it will 360 on the way down.

The boom doesn't appear to be cracked, the tail motor seems to work fine holding it in my hand it has good power and sounds the same as my older K110 that is way more beat up but never had this problem.

I have recalibrated in 3D, (but not 6G) with no luck. Any ideas? Messed up gyro?
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Old 03-31-2017, 07:11 PM   #2 (permalink)
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Are your blades tracking properly? Might be caused by a bent feathering shaft. Are you running a low throttle percentage?

I've found that both of these will screw up the tail on this model. I think that the out of track blades caused by a bent feathering shaft causes more wind resistance and the tail can't handle it as well. It also seems to not respond well when the head isn't up to at least 60-70% throttle.
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Old 03-31-2017, 09:45 PM   #3 (permalink)
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Servo?
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Old 04-01-2017, 07:30 PM   #4 (permalink)
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Servos are fine. I'll check the feathering shaft, and the tracking; it flew pretty OK yesterday, and today I managed to badly bend the main shaft, so both my birds are out of commission with the same problem. Guess hitting fences will do that Now I wish I ordered more main shafts, thought the first one was a freak thing!
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Old 04-08-2017, 06:28 PM   #5 (permalink)
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OK, put in new main shaft and the tail held well through 3 packs.

However, it did still rotate quite a bit when cutting the throttle in normal mode. Now I'm wondering if this is typical in normal mode? I usually just fly idle up so I'm not sure, can anyone confirm this? Put your heli up 15 ft, cut the throttle back to 1/4 and see if the tail holds.
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Old 04-09-2017, 10:44 AM   #6 (permalink)
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Quote:
Originally Posted by LiquidDrift View Post
OK, put in new main shaft and the tail held well through 3 packs.

However, it did still rotate quite a bit when cutting the throttle in normal mode. Now I'm wondering if this is typical in normal mode? I usually just fly idle up so I'm not sure, can anyone confirm this? Put your heli up 15 ft, cut the throttle back to 1/4 and see if the tail holds.
Cutting the throttle, meaning to go to 0%?
Heli would stop and drop.
Then go 15ft up high and lower throttle to 25%?
Tail will hold at desired speed, unless you have a loose tail blade after several crashes, bent feathering shaft, high pitch and bogging heli. That's not normal.

Post your readings on normal mode, fold the blades, measure the distance between the blades at low and high stick, now on idle up, same method and post them.

Blades track ok?
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Old 04-09-2017, 04:45 PM   #7 (permalink)
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Yes, I meant cut throttle to 25%, or whatever might produce a tail hold loss.

OK, I replaced the feathering shaft and the tail is holding fine on pitch pumps and backwards flips, blowing out 45 degrees or so on forward flips because of my poorer collective management going that way. This feels normal like when it was out-of-the-box. Blade tracking looks good.

However, the tail blowout in normal mode cutting throttle remains. This is more of a curiosity then anything else at this point because I fly IU. If this is abnormal, then at this point I would expect a gyro problem.

The blade distance measurement was a surprise, I hadn't done this on this bird yet. In normal mode, the full distance is 47mm. In IU, the low stick distance is 35mm, high stick distance is 61mm!! It's less than 3mm from the boom!

Clearly I need to adjust the linkages, but I don't think this is the problem with the tail blowing out on throttle cut in normal mode or the weird wandering tail I WAS seeing (haven't for a while now) on takeoff/hover.
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Old 04-10-2017, 10:35 AM   #8 (permalink)
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One problem at a a time to get to where you want to be.
I have 40mm between the blades on idle up, but that's just me, going higher will bring more problems than solutions, but again that's just my opinion.

I would get a new tail motor and get k120 tail blade.

Weak batteries would do what you are describing too.
What charger are you using?
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Old 04-13-2017, 06:16 PM   #9 (permalink)
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I adjusted the linkages and got it to 47mm up, 45 down. I could adjust the pitches, but I rarely go full stick on the collective in either direction.

It's got a K120 tail blade on it already. Don't think there's a problem with the motor, it sounds very healthy when I give it rudder in my hand. I'm using the cheapo charger that came with the goo batteries. They charge from 4.19 - 4.25. Haven't had a problem with them yet.

Flew it today after adjusting the linkages, was flying great halfway through the first pack and BOOM the head exploded! I heeded the warnings and threadlocked the damned thing too, just a few days ago! Ughh!
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