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Old Oct 11, 2012, 08:10 PM
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V911 Cannot sustain fast forward flight problem. Help appreciated

Hi I am new here. I appreciate any help in advance. I have a v911 for about a month. It balance itself alright. No TBE, but a bit pendulum effect when on stopping which from what I read everywhere it is normal. However on trying to sustain forward flight, and in particular when you push the stick full forward, the nose will dip to start with and the heli move forward. However the nose will slowly rise up and the heli would slowly level itself again, all the while I had my forward stick fully forward. After it levels and with the forward movement stops, as I still have my stick fully forward, the nose will dive again and the heli will move fast forward again.

Is this normal? I add a bit of weight to the nose and it helps a bit but not ideal. I am guessing the flybar will always try to level itself, and with the nose dip, the center of gravity shift, the main weight of the heli always to try go back the center and cause the nose to rise again. In short, I can only manage short bursts of fast forward movement, I cannot sustain it as nose tends to dip and rise, then dip and rise again.

Any tip will be appreciated. thanks
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Old Oct 11, 2012, 11:34 PM
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United States, KS, Wichita
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That is weird. I wonder if you have a gyro problem. Have you checked all your linkage to the flybar and blades, to make sure none of the ball links are pushed on to far?
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Old Oct 12, 2012, 12:21 AM
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That seems pretty normal for that type of heli. The trick is to not let the flybar catch up by using a lot of movement changes. There is a flybar change that is supposed to help.
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Old Oct 12, 2012, 12:53 AM
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The silver button on the upper left of the transmitter is a toggle switch that lets your heli tilt further forward when enabled. It may help.
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Old Oct 12, 2012, 01:54 AM
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I know this is gonna sound odd but try pulsing your foward direction a bit i had one v911 with bad tbe and it works. Alas i has nothing to fly at the moment so all i can do is lurk and try to help with what i have learned myself.
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Old Oct 12, 2012, 06:23 AM
KDS450QS(ZYX4),V977,CX-20
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Not gyro

Quote:
Originally Posted by livingword26 View Post
That is weird. I wonder if you have a gyro problem.
The gyro controls the tail motor, which would cause yaw problems. For stabilization, it's the job of the flybar.
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Old Oct 12, 2012, 06:24 AM
KDS450QS(ZYX4),V977,CX-20
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Ensure that both the hardware and electronic rates are set at "high".
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Old Oct 12, 2012, 08:20 AM
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What I have done to achieve better performance in FFF is first to take out all the transmitter trims and trim the heli manually till it hovers in place. Next add about one turn to the swash link so the heli now has just a bit of forward movement. Then of course always keep it on high rates so you get maximum tilt. I have also noticed by pulsing the throttle, the flybar doesn't have time to counter the FFF.
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Old Oct 12, 2012, 10:40 AM
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It's like flying a coax, if you want to keep moving forward, give it a little zig-zag motion. RCG member MassiveOverkill has a mod that uses the MSR flybar that is supposed to aid V911 performance. A high degree of mechanical stabilization doesn't go well with performance and speed. Use the old coax trick of shortening the flybar and reducing the weights.
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Old Oct 16, 2012, 02:19 AM
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Sorry for the late response as I was away for couple days. Thanks for all that! I also read somewhere about at FFF, one side of the blade going forward will be cutting through the coming wind faster than when the blade is coming back, so it will create a lift that will in turn lift the nose up. If that is so, not sure what we can do about that, but I sure know mine V911 is lifting sooner that what other v911s I saw on youtube. I will give zigzag and throttle pulse a try. And yea make sure the flybar is loose!
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Old Oct 16, 2012, 12:03 PM
Sir Crashalot
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You can also experiment with tightening the flybar a bit, you'll be able to hold the tilt of the heli longer before the self correction kicks in, which will give you the faster speed you are seeking, but you also get some pendulum, which you will need to correct yourself.

That stuff about the advancing blade creating more lift than the trailing blade; while may be true, I think it's more of an academic issue than a practical one.
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Old Oct 16, 2012, 12:28 PM
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Quote:
Originally Posted by stonecutter View Post
You can also experiment with tightening the flybar a bit, you'll be able to hold the tilt of the heli longer before the self correction kicks in, which will give you the faster speed you are seeking, but you also get some pendulum, which you will need to correct yourself.
I'm no professional but, the flybar swivels on its axis, 2 times during each rotation. Any amount of drag, can cause TBE, as well as reducing, or preventing, the heli's self correcting capability. I cannot see how it could help maintain, a stable ff flight.
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Old Oct 16, 2012, 01:31 PM
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TBE is induced by a harmonic distortion in the flybar, it has nothing to do with drag, as drag is constant. It could be bent (unlikely), too tight, too loose, the mounting or linkage could be worn, it could be binding in one spot; lots of things that are hard find. But, TBE is never caused by something that is consistent through the full 360 rotation. The pendulum effect is swaying back and forth when attempting to stop. It's more common in some micros in others. It's something like a car with bad shocks when you try to stop, it doesn't have enough damping effect. Restricting the flybar movement or capabilities reduces damping effect. Delaying or reducing damping allows forward flight longer, before the flybar catches up. If you want a micro FP that isn't slowed by the flybar, find a used Blade MSR, of get a micro without a flybar.
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Old Oct 16, 2012, 03:59 PM
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Quote:
Originally Posted by Balr14 View Post
TBE is induced by a harmonic distortion in the flybar, it has nothing to do with drag, as drag is constant. It could be bent (unlikely), too tight, too loose, the mounting or linkage could be worn, it could be binding in one spot; lots of things that are hard find. But, TBE is never caused by something that is consistent through the full 360 rotation.
You say that a flybar that is to tight could cause TBE. Wouldn't that cause drag, or friction, on the motion of the flybar? And wouldn't it be consistent through the full rotation? Stonecutter was talking about tightening the flybar. How does a tight flybar cause TBE if not because of drag? Just trying to understand.
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Old Oct 16, 2012, 04:15 PM
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My experience with these micro helis is that if the flybar is tight, it's usually a symptom of a problem, rather than the cause.
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