- 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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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. -
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.Comment
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You may have the video set to private. It says I don’t have access to view it.Comment
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Shoot! Let me check. Im real new to youtube stuff.Comment
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IT says it is "public" no restrictions. Im not sure. I can click it and it plays but that's on my computer. if you are willing to send me your email or phone number in a private message I can send it to you that way. I need all ideas.Comment
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Ok. So it actually wasn't published. My bad :). I don't know if that link will work so try this one.
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Thanks! Works fine now. Definitely try balancing the tail rotor blades and try it again. There was a lot of vertical oscillation on the tail rotor gearbox during start. Generally, that would indicate an out of balance tail rotor.Comment
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Thank 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.Comment
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Yes, that is VERY far out of balance! I usually balance all of my blades (main and tail) to within +/- 0.01g before flight. 0.05 oz = 1.42 grams. Normally, I've used high build primer to add weight to light blades until the set matches, but something seems off here. What is the accuracy on your scale? If it really is that far off, I would consider a new set of tail blades, as I'd suspect some sort of defect.. I would also highly recommend buying a cheap gram scale like this one: https://www.amazon.com/American-Weig.../dp/B0012LOQUQ. Your average kitchen type scales don't have enough precision for the job.Originally posted by Aces View PostComment
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Thank you. I really have no idea how accurate it is. Its just a simple digital scale. I will check to see if someone has one near me or I will order one. I guess I can just add tape to the lighter one to bring it up to the others and see if that makes a difference.Comment
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Did you get this problem sourtedComment
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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.Comment
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Glad you got it, this can also happen if your gain is set too high.Originally posted by Aces View PostComment
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