Walkera DragonFly v2 4ch shaking  
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All Forums >> RC Helicopters >> Electric RC Helis >> Walkera Helis - Dragonfly, etc.. >> Walkera DragonFly v2 4ch shaking
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Walkera DragonFly v2 4ch shaking - 5/13/2005 8:18:32 PM   
tomsecret


 

Posts: 9
Joined: 11/29/2003
From: Trondheim, NORWAY
Status: offline 		Hi!

I've just bought a Walkera DragonFly v2 4ch. When I try to fly the heli starts to shake, and eventually it shakes so much that it's impossible to control. I can take off, but when I'm about to start hovering at 10-15 cms the heli just can't be controlled anymore because of the shaking. Does anyone know what could be wrong? When the heli is on ground with the engine running, it looks like the rotor doesn't follow a perfect circle. Could the main rotor gear be crooked?

Tom

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< Message edited by tomsecret -- 5/13/2005 8:31:30 PM >
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RE: Walkera DragonFly v2 4ch shaking - 5/14/2005 3:41:07 AM   
oops


 

Posts: 664
Joined: 2/26/2005
From: Perth, AUSTRALIA
Status: offline 		Hi Tomsecret,

It's caused by Gyroscopic Instability. A direct consequence of low head speed and slight imbalance in the rotor.

A lot of us worked through this problems... I solved it by adding a bigger battery, but I think CptSnoopy was the first to completely resolve it.

It's caused by instability in the present rotor. Simply put, yours is unbalanced. Trying to balance the rotor as well as you can is the first step. Make both sides the same weight. Additionally, the Walkera Dragonfly isn't that symmetrical in the parts. Reversing the rotor head sometimes improves things. Whatever, it usually goes one way better than the other.

Also, the paddles should be FLAT and in the same plane as the flybar. Not angled up or down relative to each other. When looked at from the front, with one on each side, it should look like they are just a thin stick. (With the swashplate level).

The linkages should move freely. The paddles should move with just a breath!... Seriously !. If not, you may need to remove your head and improve the tolerances where the hollow brass bearings hold the flybar center section.

Now, when powered up, and move the swashplate (not flying speed) you should see serious movement of the flybar in the direction of collective.

That's the basics, but it won't resolve your issue (most likely). Now follow these instructions in order, and at some point, you will find stability improves. Each change gives more stability.


1). Tighten the rotor screws... As tight as they will safely go. Always align the blades by hand before each flight.

That's a BIG one. Trust me on that.

2) Add an 8 cell battery.

The extra weight means more head-speed is required to fly. That's a BIG one. You also get around twice the flying time over a 7 cell.

3) Shorten the main rotor slights (maybe 1 or 2 cm).

That means MORE head speed to take off, which means more stability.

4) Alternative to 3 - Flatten the blades slightly -

Less pitch means more head speed, which means more stability.

That's about it.

Others also usually gave up on the training kit. It makes things worse.... And they are easier to fly without the kit. Go figure. You'd think the extra weight would improve things but it doesn't.

Mine did the same. Was unflyable. Now I can fly it in a 1sq meter space indoors... I even took it to work and flew it over the cubicles... (yes, reasonable safety precautions observed.... Everyone knew what was happening... Noone under the Heli. )

Now with the higher headspeed, it even handles severe rotor damage quite well.

Oh - a final change - good wooden rotors. Very stable. I've gone back to shortened plastic though More damageproof.

Regards
David

(in reply to tomsecret)
       Post #: 2

RE: Walkera DragonFly v2 4ch shaking - 5/14/2005 9:21:35 AM   
tomsecret


 

Posts: 9
Joined: 11/29/2003
From: Trondheim, NORWAY
Status: offline 		Thanks alot David! I'll try all your tips, but I don't think I'll cut of the blades an that, because then I can't return it to the seller

(in reply to oops)
       Post #: 3

RE: Walkera DragonFly v2 4ch shaking - 5/16/2005 1:56:53 AM   
ACE11


 

Posts: 8
Joined: 4/24/2005
From: kentville, NS, CANADA
Status: offline 		my dragonfly has a bad wobble also, i did all the mods even got like90 fixed pitch blades but still has the wobble any more ideas? whats a good servo to change to? any help is apperciated.

(in reply to tomsecret)
       Post #: 4

RE: Walkera DragonFly v2 4ch shaking - 5/16/2005 3:46:37 AM   
cptsnoopy


 

Posts: 540
Joined: 2/26/2005
From: Phoenix, AZ, USA
Status: offline
quote:

ORIGINAL: tomsecret

Hi!

I've just bought a Walkera DragonFly v2 4ch. When I try to fly the heli starts to shake, and eventually it shakes so much that it's impossible to control. I can take off, but when I'm about to start hovering at 10-15 cms the heli just can't be controlled anymore because of the shaking. Does anyone know what could be wrong? When the heli is on ground with the engine running, it looks like the rotor doesn't follow a perfect circle. Could the main rotor gear be crooked?

Tom


Hi tomsecret,

oops (David) pretty much covered it. here is what I did to help eliminate my wobbles:

1)remove the main blades and compare them on a sensitive scale. mine where pretty far off in weight. i used sandpaper on the leading and trailing edges of my heavy blade until it weighed the same as the light one. then i put them back on and tightened the screws up as tight as i dared before stripping the plastic nuts. while i had the main blades off i checked the flybar paddles to make sure they were parallel with each other and the rod was equal length on both sides. then i throttled up the heli with the main blades off to check the balance of the flybar system. mine looked good so then i put the main blades back on. this alone solved most of the wobble issue. but i found the heli would wobble for a couple of reasons even after balancing. one was if i made abrupt control movements especially with the throttle and second worse was with roll or pitch. i got less wobbles the smoother i controlled the heli. the other cause i found was trying to fly at any speed faster than just creeping along. i would get the wobbles when i flew forward then tried to slow down. instant wobbles... i have found that i can fly around at speed as long as i keep it in a steep turn. if i don't recover from the steep turn very smoothly and carefully the wobbles can start. if you fly outside in any breeze this can contribute also. ok onto the next steps:
2) if you don't already have one, you should get ahold of the little metal plate that bolts on to the bottom side of the rotor head using the same screws that hold the main blades on. this plate reduces the amount the rotor head can flex and reduces coning. this help prevent the wobbles too.
3) i stopped using the NimH battery and bought a 7.4 volt 2cell lithium Polymer battery and for whatever reason it seemed to help also. I get about 15 minutes of steady flight time from the battery and the heli flys better.
4) stop using the training landing gear as soon as you feel you can. it contributes to the wobbles in a big way.

I have not done anything to increase head speed yet but I am sure that would help a bunch too.

as you can see, various things can help and if possible you should try them all and maybe you will think of some other helpful things that would work.

Hi ACE11,

I have not yet gotten the like90 blades but want to. I am surprised that it did not help out. do you have the rotor head stiffener installed? please double check that the rotor system is balanced and turning smoothly without any main blades on. you may want to try tightening the mainblade screws or if they are already tight, then try loosening them a tad..? as far as servos go I used GWS naro servos on my number 4 and they work great. I used hitec HS55's on my number 35 and it seems to be doing pretty good so far... the HS55's are a closer match to the original walkera servos but they cost a couple of dollars more.

(in reply to tomsecret)
       Post #: 5

RE: Walkera DragonFly v2 4ch shaking - 5/16/2005 9:42:16 AM   
tomsecret


 

Posts: 9
Joined: 11/29/2003
From: Trondheim, NORWAY
Status: offline 		Thanks for all the help! I've removed the training gear and tightened the screws for the main motor blades - that seemed to do it. The main motor gear still seems to be crooked as the rotor doesn't follow perfect circles (it isn't THAT far from it ), but it is steady enough now. Well at the moment the heli is grounded because I broke one of the main blades in a crash yesterday. I've glued it with 30 min epoxy, but I have my doubts that will be strong enough...

This heli really got me hooked into helicopters, I'm looking for an upgrade now and I will probably go for the T-Rex 450X (or XL), or a Mikado Logo 10, but I should probably learn flying the dragonfly a little better before I order one

(in reply to cptsnoopy)
       Post #: 6

RE: Walkera DragonFly v2 4ch shaking - 5/17/2005 2:28:27 AM   
ACE11


 

Posts: 8
Joined: 4/24/2005
From: kentville, NS, CANADA
Status: offline 		well i replaced the head screws done away with the plastic nuts went to meatl ones, seems to be better, more stable anywaybut it's raining here in n.s so my test run will have to wait until tomorrow thanks for all the help ill keep you posted on how i make out.

(in reply to tomsecret)
       Post #: 7

RE: Walkera DragonFly v2 4ch shaking - 5/17/2005 9:53:17 AM   
cptsnoopy


 

Posts: 540
Joined: 2/26/2005
From: Phoenix, AZ, USA
Status: offline 		sounds good ACE11...

on the subject of getting the blade tight to avoid the wobbles I was drinking a little too much and crashed my #4 into the coffie table. one of the original main blades broke off near the root. so I got out the spare blades that came with the heli. we had balanced this set at the same time we did the original ones. so i just put them on and was surprised to see that they are just slightly thinner at the root so they cannot be tightened up enough to keep them from swinging freely. I thought hey what the heck i'll just try it anyway. the heli flew just fine and no wobbles. keep in mind though that this is indoor and with no horizontal movement. when i ran the battery down i got out the 22d and loosened up the main blades to see what it would do. the 22d was less stable and tended to wobble a bit with the blades loose. when they were tightened back up it made a very noticable difference and it flew much more stable.

(in reply to ACE11)
       Post #: 8

RE: Walkera DragonFly v2 4ch shaking - 5/17/2005 10:18:42 AM   
ACE11


 

Posts: 8
Joined: 4/24/2005
From: kentville, NS, CANADA
Status: offline 		im not brave enough to fly indoors yet, but when i can that cat of mine is gonna get it.

(in reply to cptsnoopy)
       Post #: 9

RE: Walkera DragonFly v2 4ch shaking - 5/18/2005 12:36:22 AM   
ACE11


 

Posts: 8
Joined: 4/24/2005
From: kentville, NS, CANADA
Status: offline 		well i tightened the like90 blades up to stop the wobble then at about 3/4 throttle to lift off it just dove into the ground smashing the flybar and the square piece below it .my heli just wont fly i guess, as far as i know im the only one in my area with a micro electric, the hobbie shops is 45 minutes away and don't sell them special order only and my dragon fly will be 350 canadian there without a batt. or charger.If anyone can give me some ideas on how to set this thing up better than i have or give me your phone number ill call you long distance i just have to fly this thing.i won't be beat by it.

(in reply to ACE11)
       Post #: 10

RE: Walkera DragonFly v2 4ch shaking - 5/18/2005 11:39:26 AM   
cptsnoopy


 

Posts: 540
Joined: 2/26/2005
From: Phoenix, AZ, USA
Status: offline 		thats a bummer ACE11...

did you switch servos yet? I cant understand why it would do that unless you tried to take off too gently. if you don't spin up the blades, then lightly "pop" it off the ground a few inches by pushing the throttle up rapidly just enough to get it off the ground, it will try to tip over when it is just about ready to lift its own weight. the other possiblility is the radio or one of the servos "glitched" and caused it to pitch over...

< Message edited by cptsnoopy -- 5/18/2005 11:42:21 AM >

(in reply to ACE11)
       Post #: 11

RE: Walkera DragonFly v2 4ch shaking - 5/18/2005 8:09:11 PM   
ACE11


 

Posts: 8
Joined: 4/24/2005
From: kentville, NS, CANADA
Status: offline 		i spool it up to the point it starts to umm well become light on its landing gear the i throttle it to achieve lift off however this time was trouble . lol,i have a great sense of humor this doesn't bother me to much ill never give up,it's not my personality.im going to get new servos this week-end as its a long drive to the hobbie shop.thanks for the help

(in reply to cptsnoopy)
       Post #: 12

RE: Walkera DragonFly v2 4ch shaking - 5/20/2005 4:58:33 PM   
Heliboy71


 

Posts: 3
Joined: 5/19/2005
From: Melbourne, AUSTRALIA
Status: offline 		Guys , thanks for all your excellent info,
i have been flying helis for ages, gas / electric, large and micro - and have only come across the shaking problem after buying a skyhawk aerohawk second hand from a friend, and then purchasing the walkera (DF) off ebay..
at first i was so excited whrn it come to the house in a brown paper box.
i ripped it open , only to find when i took off, it shook like all get aout!
i was very pissed off... then i read this forum, and i am truely grateful.

After tightening the rotar blades and fixing the battery CG , it flies like a dream.

also i have replaced the walkera box (speddy/gyro/receiver/ with my own 35 mhz receiver and an old E-sky speedy/gyro unit
seems to work a treat, and i can now fly it using my HITEC 7 eclipse radio.

I did fly it in the lihge room for about 20 minutes landing on coffee table and taking off etc, however when the 7.4 lipo started to die, i lost control of the tail whilst in a very tight turn near the wall heater.. and BANG - we lost a blade housten.

I then went out to the "garage of death" as i call it, and founda anohter set of DF fixed pitch baldes - i replaced the broken on only,
and found that the heli shook like made again on take off. a strip of electrical tape on the unbroken blade , and hey presto. we are balanced again.

I am running a 7.4 620 mah lipo as the weight is quite good, is anyone else running this type of battery? i get about 10 minute of use.

anyway, thanks again for some very useful and helpful advice.

Luke Raisbeck
Cameraman / Director / Editor / RC Heli Pilot.

(in reply to ACE11)
       Post #: 13