- So I have a technical question for those with the Apache or just those with wisdom beyond mine. I have just completed the build of the mechanics on this 700 Apache and did my first test hover. It seems I have an oscillation going on Im trying now to track down. At first I thought maybe the gains were too high on the tail rotor gyro but after lowering them and playing with them some I still have the oscillation. I removed the tail blades to weigh them ( I had not originally and I have not balanced them) and three were .25oz and one was .20. You think that's enough to cause the oscillation? I checked for binding on the tail servo wire but it seems real smooth. I am going to check the blades for balance and weight but I don't think the issue is originating from there.
My other concern is that I built a wood platform to test the mechanics on and I am wondering if the two braces for the boom is enough to keep the tail from flexing and possibly causing this.
I am sure that installed in the fuselage there is more stability. And advice would be appreciated.
I have pics but I guess they are too big? It wont let me load them.
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Roban 700 Apache oscillation
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Roban 700 Apache oscillation
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Which direction is the oscillation? I assume it is in yaw? If in yaw, it could be any or a combination of the following factors:
Slop in ball links or tail rotor pushrod
Too slow of a Tail Servo
Slop in Tail rotor pitch slider
Too much friction on tail rotor pushrods or bellcrank mechanism
Tail rotor balance
I would definitely balance out the tail rotor for a start. I usually balance each blade within 0.01 grams, and that has worked well. If it is not purely a yaw oscillation, try playing with your head gains. My 500 Apache had a longitudinal oscillation that required some significant adjustments on the head gains in order to eliminate.
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Thank you for the ideas. I will double check ball links but I believe they are fine. I have high speed HV servos that are .08sec at 7.4v. Better than most of the servos I used on my Align 700.There is a little bit of slop in the tail rotor but not what I would consider enough to cause this. I had as much on my aligns and they flew fine. There is not friction on the bellcrank or pushrod. I will have to balance the blades just to be sure and I will sand them down to match in weight.
This is my first time with a four blade head so I will definitely try playing with settings. I will see if I can link to a video.
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Originally posted by Aces View PostThank you. I have weighed the tail blades and one is .20oz while the other three are .25. Is that enough to throw off the balance? And when it comes to actually balancing the blades. what method should I use? I honestly have never done it before.
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Hello. rushute. Sorry for the late reply. I did finally figure it out. After everything i did (going though all kinds of problem shooting) it ended up being simply that my ball was too far out on the tail servo arm and it was fighting itslef!!! Whats interesting is that a friend of mine thought about this and i moved it in one hole from where it was with no change. It needed to be move in another hole. Flys great now.
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Originally posted by Aces View PostHello. rushute. Sorry for the late reply. I did finally figure it out. After everything i did (going though all kinds of problem shooting) it ended up being simply that my ball was too far out on the tail servo arm and it was fighting itslef!!! Whats interesting is that a friend of mine thought about this and i moved it in one hole from where it was with no change. It needed to be move in another hole. Flys great now.
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