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4G6 / V120 Series Walkera 4G6 / V120 Series Helicopter Support


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Old 04-11-2011, 04:58 PM   #1
Wingman6
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Default Shutter after changing to 2s setup

I finally upgraded my novus 125 cp to a hyperion 5300 2s set up. The power is great however i notice that during flying it occasionally has this shutter (small wobble). It didn't have this before i upgraded and i'm not sure i bent anything...

Anything anyone can think of that might be causing this? I might replace the feathering shaft just to be sure as i was doing some of the work upside down but i can't think of what else changed.

Thanks for the help.
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Old 04-12-2011, 03:33 AM   #2
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Quote:
Originally Posted by Wingman6 View Post
I finally upgraded my novus 125 cp to a hyperion 5300 2s set up. The power is great however i notice that during flying it occasionally has this shutter (small wobble). It didn't have this before i upgraded and i'm not sure i bent anything...

Anything anyone can think of that might be causing this? I might replace the feathering shaft just to be sure as i was doing some of the work upside down but i can't think of what else changed.

Thanks for the help.
The higher headspeed with your 2S setup will show some of the imperfections of your setup, that did not show up with lower headspeeds. You can consider rebalancing blades, replacing feather shaft, replacing main shaft, replacing main gear, look at the main frame bearings, look at your swashplate, fixate your Rx better. However, you may want to decrease sensitivity on your Rx first....in case it is the Rx gyros overreacting to an otherwise harmless imperfection.
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Old 04-12-2011, 11:11 AM   #3
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yes all of the exellent tips Hjns gave...

plus:

after balancing blades, make sure blade tracking is dead on.

sometimes you might have to balance the tail rotor. I always do, whether 1S or 2S.

check out the tail servo, these can get flakey and not show anything until you run 2S headspeeds

check play tail: rotor shaft, tail drive shaft, tail rotor shaft bearings, the tail slider and arm and the gears in the rear ("d" holes getting rounded out)

check fgor jittery cyclic servos too.

and 2S power can crack carbon tail drive shafts and or split the ends so the gears do not fit tightly. Cossider TI or Steel tail drive shaft for 2S.


all of these, plus what Hjns listed, can cause what you are seeing. I suggest you turn down gyoe sens at the RX as the last resort, after EVERYTHING else done.

j
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Old 04-12-2011, 12:51 PM   #4
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Thanks for all the great tips. This definitely makes sense that the greater headspead can cause this to be exaggerated.

I guess i need to go through the bird and start checking out things. I am currently running the Ti drive shaft and i think the tails gear should be ok as i just replaced 2/3 when i did the Ti shaft and microheli tail gear box.

I never balanced the blades so i'm guessing this and the feathering shaft are the two best places to start. Any tips on how to do this? I also need to adjust the gear mesh and replace the main gear as i hear a bit of a hum in the main gear at speed.

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Originally Posted by taosgraveyard View Post
yes all of the exellent tips Hjns gave...

plus:

after balancing blades, make sure blade tracking is dead on.

sometimes you might have to balance the tail rotor. I always do, whether 1S or 2S.

check out the tail servo, these can get flakey and not show anything until you run 2S headspeeds

check play tail: rotor shaft, tail drive shaft, tail rotor shaft bearings, the tail slider and arm and the gears in the rear ("d" holes getting rounded out)

check fgor jittery cyclic servos too.

and 2S power can crack carbon tail drive shafts and or split the ends so the gears do not fit tightly. Cossider TI or Steel tail drive shaft for 2S.


all of these, plus what Hjns listed, can cause what you are seeing. I suggest you turn down gyoe sens at the RX as the last resort, after EVERYTHING else done.

j
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Old 04-12-2011, 01:05 PM   #5
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too tight on the mesh will do it, and I guess too loose could do it too.

if you changed pinion sizes (going up) without setting mesh, the hum could mean too tight, which can cause shudders.

if you replaced the stock motor, i bet you are now running a pinion with more teeth

regarding blade balancing, this gets covered a lot , search this thread for those terms. or go to the helifreak setup videos.

I use an xtreme mag base blade balancer and like it a lot, but there is a bit to know about balancing before you et to that stage.
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Old 04-12-2011, 01:11 PM   #6
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I did replace the motor and went to a 17t pinion. I'm trying to decide whether i'm too tight or too loose on the mesh. When the blades begin to spin up it sounds "normal" but as i get the speed up i starts to hum or whine a little, almost sounding like it is missing a bit, though hard to tell.

The mesh seems to be a bit of an art and i'll have to play with it a bit.

I will also look into the blade balance.

Thanks for the help, trying to get this thing solid in the air. BTW, my gyro is 10-20% sensitivity and the aileron and elevator are at about 50%.

I'm guessing i should try dropping this back a bunch to see if it is a servo problem.

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Originally Posted by taosgraveyard View Post
too tight on the mesh will do it, and I guess too loose could do it too.

if you changed pinion sizes (going up) without setting mesh, the hum could mean too tight, which can cause shudders.

if you replaced the stock motor, i bet you are now running a pinion with more teeth

regarding blade balancing, this gets covered a lot , search this thread for those terms. or go to the helifreak setup videos.

I use an xtreme mag base blade balancer and like it a lot, but there is a bit to know about balancing before you et to that stage.
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Old 04-14-2011, 02:23 PM   #7
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Thanks for all the replies on this. I checked the feathering shaft and sure enough there was a slight wobble in the blade holder when i turned the screw.

I'm guessing this was there before i upgraded but wasn't' severe enough to show itself as a wobble.
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Old 04-14-2011, 03:59 PM   #8
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Oh yes a 2s setup will show all weaknesses in your heli!! Especially when you run it at 100% throttle

Also consider replacing the stock dampers with stiff o rings. Will make head run smoother and provide crisp response. No more wallowing aound felony in a hover due to soft dampers.youmifhtstill have a cushy heli, but the dampers can be ruled out as causing it if you go astiffer. I like my helis to be REALLY responsive, and run 100% travel and 15% ( sometimes 10%) expo on cyclic servos. I want stiff dampers.

Club heli has them

I use 90s on everything
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Old 04-29-2011, 12:37 AM   #9
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I replaced the feathering shaft and i still get a shutter or wobble around 50-60% aileron and elevator. I turned in down and at about 40% things seem to get better. Does this suggest an issue with the servos or is it something with my set up.

I also replaced the blades and that didn't seem to improve the set up either.

Thanks

Quote:
Originally Posted by taosgraveyard View Post
yes all of the exellent tips Hjns gave...

plus:

after balancing blades, make sure blade tracking is dead on.

sometimes you might have to balance the tail rotor. I always do, whether 1S or 2S.

check out the tail servo, these can get flakey and not show anything until you run 2S headspeeds

check play tail: rotor shaft, tail drive shaft, tail rotor shaft bearings, the tail slider and arm and the gears in the rear ("d" holes getting rounded out)

check fgor jittery cyclic servos too.

and 2S power can crack carbon tail drive shafts and or split the ends so the gears do not fit tightly. Cossider TI or Steel tail drive shaft for 2S.


all of these, plus what Hjns listed, can cause what you are seeing. I suggest you turn down gyoe sens at the RX as the last resort, after EVERYTHING else done.

j
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Old 04-29-2011, 12:57 AM   #10
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This is either:

1. Vibration Issue
2. Gyro Isolation (mounting) Issue

What I do, is remove the tail rotor blades, main rotor blades, and rotor head. Spin it up on the bench and check for vibes. Keep adding stuff back to the heli and checking for vibes. This will help you determine the issue.

The motor shouldn't require balancing since it's an inrunner (love how smooth these Hyp's are).

You may also want to experiment with different gyro mounting options, variations of tape, and reinforcement of the gyro tray.

If you are using the stock frame, you will want to upgrade either to the Xtreme or MicroHeli frames.

Also check your bearings if you have a lot of flight time on your heli.

Did you balance your main rotor blades dynamically?
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Old 04-29-2011, 01:22 AM   #11
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Thanks for the input, i'll give this a try.

It was interesting that when using only 40% the heli seemed to fly super smooth but at higher rates there was the shutter. I could see the the servos giving constant input back and forth it seemed.

When i test removing a few of the parts, what should i have the gyro settings at.

At the moment i just have my gyro on some doubled sided tape and stuck to the stock frame and then the ESC is stuck to that.

As far as bearings go, i don't believe i have enough flights for those to go but i guess it is possible.

Quote:
Originally Posted by Crazy_Canuck View Post
This is either:

1. Vibration Issue
2. Gyro Isolation (mounting) Issue

What I do, is remove the tail rotor blades, main rotor blades, and rotor head. Spin it up on the bench and check for vibes. Keep adding stuff back to the heli and checking for vibes. This will help you determine the issue.

The motor shouldn't require balancing since it's an inrunner (love how smooth these Hyp's are).

You may also want to experiment with different gyro mounting options, variations of tape, and reinforcement of the gyro tray.

If you are using the stock frame, you will want to upgrade either to the Xtreme or MicroHeli frames.

Also check your bearings if you have a lot of flight time on your heli.

Did you balance your main rotor blades dynamically?
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Old 04-29-2011, 10:41 AM   #12
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I was able to eliminate a wobble in my 4G6S by adjusting the flybar paddles a little. I found that they were not totally level. I made small adjustments to them until the wobble was gone (by trial and error). Prior to this, I had already replaced the main shaft, and feathering shaft without any improvement.

It's something to try anyway...
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Old 04-29-2011, 10:51 AM   #13
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Don't worry about the gyro gain, we're just trying to locate vibes on the bench (with no blades, you're ok to hold it in your hand and spool up, just remember to wear goggles though for safety.

How many flights do you have with those bearings?

And yes, mdmaroon makes a good point, your paddles need to be adjusted for proper tracking. Best way to do this is to mark one with a little bit of white nail polish. Set them at 90deg to the main shaft. Spool it up on the ground (wear goggles) and get on the floor and watch how the white tip is tracking. If it's high, adjust the leading edge of the paddle down. If it's low, adjust the leading edge of the paddle up.
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Old 04-29-2011, 11:10 AM   #14
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Great suggestions and thanks for all the help.

I'll give that a try tonight and see how it goes. Hopefully i can get the bird solid in the air asap.

I want to say i have maybe 20-30 flights on the bearings.
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Old 04-29-2011, 08:18 PM   #15
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Just to give you a little encouragement, this heli had a bad wobble, and would shake like crazy when starting up or after landing.

I balanced the blades after watching the Finless Bob blade balancing video, and it made a big difference. I had almost eliminated the wobble with flybar adjustments, but balancing the blades helped change it from "acceptable" to "pretty good!"

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Old 04-30-2011, 04:51 PM   #16
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I did a bit of testing and the following is what I found.

With the blades off at around 50% throttle the two back servos wobble back and forth.

If I remove the head it seems to be just fine at around 50% throttle or higher.

If I put the head back on and pinch the gyro at 50% throttle or higher it seems to make the wobble go away. When I release the servos shutter again.

I'm guessing this points to a gyro mounting issue where it is vibrating.

I'm not sure what else in the head could be making it wobble. I was able to get it a bit better by playing with the fly bar paddles.

Any suggestions from what I have so far.

I have a video but I'm not sure how to post it.

Thanks
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Old 05-01-2011, 10:13 AM   #17
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Quote:
Originally Posted by Wingman6 View Post
I did a bit of testing and the following is what I found.

With the blades off at around 50% throttle the two back servos wobble back and forth.

If I remove the head it seems to be just fine at around 50% throttle or higher.

If I put the head back on and pinch the gyro at 50% throttle or higher it seems to make the wobble go away. When I release the servos shutter again.

I'm guessing this points to a gyro mounting issue where it is vibrating.

I'm not sure what else in the head could be making it wobble. I was able to get it a bit better by playing with the fly bar paddles.

Any suggestions from what I have so far.

I have a video but I'm not sure how to post it.

Thanks
Sounds to me like your mainshaft is bent. When it's bent the vibrations will cause the gyro's to mess up and your servo's will begin go shake because of it. Even the slightest bend to the mainshaft will cause this problem to occur.
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Old 05-01-2011, 12:02 PM   #18
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I can check this out but I have one of those procrasher shafts, so I hope that didn't bend.

Also, it seemed ok when just the shaft was turning, though I guess the main shaft could make the head look worse.

I'm wondering if the gyro mounting isn't great.

Here is a quick video of it...


Last edited by Wingman6; 05-02-2011 at 10:34 AM.. Reason: added video...
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Old 05-02-2011, 09:03 PM   #19
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Procrasher shafts can bend ... while extremely durable, they are not indestructable. They'll survive many crashes, but eventually, even they can bend if struck badly.

I agree, sounds like a combination of gyro mounting and bent main shaft, or even possibly a damaged / bent head. Which head are you using?

Many of us would wrap an elastic band around the gyro and mounting tray and it would help. I also found that removing the cover and ensuring the cables were not secured too tightly helped as well.
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Old 05-02-2011, 10:09 PM   #20
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I'm currently using a stay true CNC metal rotor head. i believe the shaft was that as well.

i don't recall crashing hard enough to bend anything but i'm guessing it is always possible, just depends on how the bird goes down.

I will likely start by removing the gyro cover, securing it down, and putting a rubber band around it. If that doesn't do the trick i'll probably just buy a stock main shaft and see how that works out, at least for the time being. If that doesn't do the trick, i'm guessing as you said it probably is the head.

Thanks to everyone who has chimed in on this as it is pretty frustrating at the moment.


Quote:
Originally Posted by Crazy_Canuck View Post
Procrasher shafts can bend ... while extremely durable, they are not indestructable. They'll survive many crashes, but eventually, even they can bend if struck badly.

I agree, sounds like a combination of gyro mounting and bent main shaft, or even possibly a damaged / bent head. Which head are you using?

Many of us would wrap an elastic band around the gyro and mounting tray and it would help. I also found that removing the cover and ensuring the cables were not secured too tightly helped as well.
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