Sudden Left Yaw
07-15-2004, 09:59 AM
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Sudden Left Yaw
I have this info posted on the RunRyder board too - 'cause I'm desperate with this particular setup. Sorry if you've read this before:
HB Elite FP
Main motor: HiMaxx 4100-2015 motor on a Phoenix 10 ESC
Tail Motor: GWS DD on a Pixie 7 ESC
Gyro: CSM HLG200 Head Lock
Receiver: Berg*5*DSP
Batt: 2 cell 1200 ma Li-Polys with voltage monitor
Prior to this problem starting I had flown this configuration for about 3 weeks with excellent results. I got ample power from the Himaxx motor and HH gyro held the tail just fine. This heli was stable, reliable and lots of fun to fly. I couldn't have asked for a better flying bird.
But within the last few days:
The nose makes a sudden and unpredictable 45 to 90 degree rotations to the left. It's irritating enough for this to happen once in awhile, but it's darn disorientating you're up high or if you get two or more sudden rotations within a short period. This rotation is always to the left. I can hear the tail motor's pitch lower a bit but it doesn't sound as though the motor is totally losing power, in fact this looks and sound like a quick left rudder command from the pilot. This started shortly after I replaced the Pixie 7 tail ESC with a new one, but I think this might be coincidence. I do believe that this ESC is working OK. The Previous ESC had a defective FET.
Tests I've done:
Replaced the DD Tail motor with the stock motor/prop combo.
No change.
Replaced the receiver with another that I use in an R/C plane.
No change.
I've not replaced the ESC or gyro because I don't have spares.
Radio?
Transmitter seems fine and at this point I have no reason to think that it's the source of the trouble. Servos don't seem "glitchy". I do hear a bit of the normal chatter from them at idle when the sticks are centered (as they try to maintain the neutral position on their control pots) but other than that they seem fine.
I strapped the heli down and ran it full throttle. Carefully shook, wiggled, and tugged at all wiring and connectors hoping to find something loose or intermittent. No problems found.
I can adjust the gyro gain higher and the sudden rotation becomes more abrupt. Lowering the gain causes the sudden rotation to be more gentle. I've also noticed that even though I turn the gain all the way up I can't make the tail "wag" like I used to. Previously I had the gain set to a point where the wag was minimal but still slightly noticeable. The gyro does otherwise hold the heading and generally stabilizes the heli well.
What's changed recently:
The Pixie 7 on the tail motor recently failed and I sent it back to Castle. They replaced it with a new one. I believe that it's OK, since when I did the strapped-down-full-throttle tests it never whimpered, but instead ran the DD tail motor strongly. It didn't get warm or show any signs of stress.
Any ideas as to the cause to the left yaw - before I take a hammer to this thing [:@]
HB Elite FP
Main motor: HiMaxx 4100-2015 motor on a Phoenix 10 ESC
Tail Motor: GWS DD on a Pixie 7 ESC
Gyro: CSM HLG200 Head Lock
Receiver: Berg*5*DSP
Batt: 2 cell 1200 ma Li-Polys with voltage monitor
Prior to this problem starting I had flown this configuration for about 3 weeks with excellent results. I got ample power from the Himaxx motor and HH gyro held the tail just fine. This heli was stable, reliable and lots of fun to fly. I couldn't have asked for a better flying bird.
But within the last few days:
The nose makes a sudden and unpredictable 45 to 90 degree rotations to the left. It's irritating enough for this to happen once in awhile, but it's darn disorientating you're up high or if you get two or more sudden rotations within a short period. This rotation is always to the left. I can hear the tail motor's pitch lower a bit but it doesn't sound as though the motor is totally losing power, in fact this looks and sound like a quick left rudder command from the pilot. This started shortly after I replaced the Pixie 7 tail ESC with a new one, but I think this might be coincidence. I do believe that this ESC is working OK. The Previous ESC had a defective FET.
Tests I've done:
Replaced the DD Tail motor with the stock motor/prop combo.
No change.
Replaced the receiver with another that I use in an R/C plane.
No change.
I've not replaced the ESC or gyro because I don't have spares.
Radio?
Transmitter seems fine and at this point I have no reason to think that it's the source of the trouble. Servos don't seem "glitchy". I do hear a bit of the normal chatter from them at idle when the sticks are centered (as they try to maintain the neutral position on their control pots) but other than that they seem fine.
I strapped the heli down and ran it full throttle. Carefully shook, wiggled, and tugged at all wiring and connectors hoping to find something loose or intermittent. No problems found.
I can adjust the gyro gain higher and the sudden rotation becomes more abrupt. Lowering the gain causes the sudden rotation to be more gentle. I've also noticed that even though I turn the gain all the way up I can't make the tail "wag" like I used to. Previously I had the gain set to a point where the wag was minimal but still slightly noticeable. The gyro does otherwise hold the heading and generally stabilizes the heli well.
What's changed recently:
The Pixie 7 on the tail motor recently failed and I sent it back to Castle. They replaced it with a new one. I believe that it's OK, since when I did the strapped-down-full-throttle tests it never whimpered, but instead ran the DD tail motor strongly. It didn't get warm or show any signs of stress.
Any ideas as to the cause to the left yaw - before I take a hammer to this thing [:@]
